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SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0458 PM CDT Sat Aug 16 2025 Valid 181200Z - 241200Z ...Day 3-5/Monday-Wednesday... An expanding and strengthening mid-level ridge over the Four Corners region will bring above normal temperatures but relatively light winds to much of the Intermountain West through the midweek. Mid-level troughing across the Pacific Northwest is expected to begin translating northeastward along the northern periphery of the ridge by Day 5/Wednesday, inviting drier conditions to filter into the Northwestern U.S. Ridge positioning will also usher in a northward surge of elevated monsoon moisture into the Desert Southwest by Day 4/Tuesday and by Day 5/Wednesday across the Eastern Great Basin. A dry boundary layer in place across the Four Corners and Great Basin regions will support limited rainfall from higher terrain convection and thunderstorms. Fuels are expected to remain quite dry and receptive across this region with a particular threat from new lightning ignitions. A 10 percent probability area for dry thunderstorms was introduced for Day 5/Wednesday. Farther north, the mid-level trough could support additional thunderstorms across portions of the central/northern ID and western MT Day 4-5/Tuesday-Wednesday but some uncertainty regarding antecedent rainfall distribution along with marginal fuel dryness precludes introduction of dry thunderstorm probabilities at this time. ...Day 6-8/Thursday-Saturday... Deeper monsoon moisture moving into Great Basin, with PWATs around 1.00 inch as well as rising surface dewpoints/relative humidity, should begin to limit dry lightning potential late in the week across the Great Basin and Four Corners regions with at least some wetting rains expected. Nonetheless, multiple days of higher terrain showers and thunderstorms will expand across much of the Intermountain West late next week. Lighter winds overall are expected under a building ridge over the Western U.S. along with steadily increasing temperatures, particularly across the western coastal states. A thermal trough begins to set up across CA late next week, further drying fuelscapes across the region as temperatures reach into the 100s in valley/interior locations. ..Williams.. 08/16/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0458 PM CDT Sat Aug 16 2025 Valid 181200Z - 241200Z ...Day 3-5/Monday-Wednesday... An expanding and strengthening mid-level ridge over the Four Corners region will bring above normal temperatures but relatively light winds to much of the Intermountain West through the midweek. Mid-level troughing across the Pacific Northwest is expected to begin translating northeastward along the northern periphery of the ridge by Day 5/Wednesday, inviting drier conditions to filter into the Northwestern U.S. Ridge positioning will also usher in a northward surge of elevated monsoon moisture into the Desert Southwest by Day 4/Tuesday and by Day 5/Wednesday across the Eastern Great Basin. A dry boundary layer in place across the Four Corners and Great Basin regions will support limited rainfall from higher terrain convection and thunderstorms. Fuels are expected to remain quite dry and receptive across this region with a particular threat from new lightning ignitions. A 10 percent probability area for dry thunderstorms was introduced for Day 5/Wednesday. Farther north, the mid-level trough could support additional thunderstorms across portions of the central/northern ID and western MT Day 4-5/Tuesday-Wednesday but some uncertainty regarding antecedent rainfall distribution along with marginal fuel dryness precludes introduction of dry thunderstorm probabilities at this time. ...Day 6-8/Thursday-Saturday... Deeper monsoon moisture moving into Great Basin, with PWATs around 1.00 inch as well as rising surface dewpoints/relative humidity, should begin to limit dry lightning potential late in the week across the Great Basin and Four Corners regions with at least some wetting rains expected. Nonetheless, multiple days of higher terrain showers and thunderstorms will expand across much of the Intermountain West late next week. Lighter winds overall are expected under a building ridge over the Western U.S. along with steadily increasing temperatures, particularly across the western coastal states. A thermal trough begins to set up across CA late next week, further drying fuelscapes across the region as temperatures reach into the 100s in valley/interior locations. ..Williams.. 08/16/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0458 PM CDT Sat Aug 16 2025 Valid 181200Z - 241200Z ...Day 3-5/Monday-Wednesday... An expanding and strengthening mid-level ridge over the Four Corners region will bring above normal temperatures but relatively light winds to much of the Intermountain West through the midweek. Mid-level troughing across the Pacific Northwest is expected to begin translating northeastward along the northern periphery of the ridge by Day 5/Wednesday, inviting drier conditions to filter into the Northwestern U.S. Ridge positioning will also usher in a northward surge of elevated monsoon moisture into the Desert Southwest by Day 4/Tuesday and by Day 5/Wednesday across the Eastern Great Basin. A dry boundary layer in place across the Four Corners and Great Basin regions will support limited rainfall from higher terrain convection and thunderstorms. Fuels are expected to remain quite dry and receptive across this region with a particular threat from new lightning ignitions. A 10 percent probability area for dry thunderstorms was introduced for Day 5/Wednesday. Farther north, the mid-level trough could support additional thunderstorms across portions of the central/northern ID and western MT Day 4-5/Tuesday-Wednesday but some uncertainty regarding antecedent rainfall distribution along with marginal fuel dryness precludes introduction of dry thunderstorm probabilities at this time. ...Day 6-8/Thursday-Saturday... Deeper monsoon moisture moving into Great Basin, with PWATs around 1.00 inch as well as rising surface dewpoints/relative humidity, should begin to limit dry lightning potential late in the week across the Great Basin and Four Corners regions with at least some wetting rains expected. Nonetheless, multiple days of higher terrain showers and thunderstorms will expand across much of the Intermountain West late next week. Lighter winds overall are expected under a building ridge over the Western U.S. along with steadily increasing temperatures, particularly across the western coastal states. A thermal trough begins to set up across CA late next week, further drying fuelscapes across the region as temperatures reach into the 100s in valley/interior locations. ..Williams.. 08/16/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0458 PM CDT Sat Aug 16 2025 Valid 181200Z - 241200Z ...Day 3-5/Monday-Wednesday... An expanding and strengthening mid-level ridge over the Four Corners region will bring above normal temperatures but relatively light winds to much of the Intermountain West through the midweek. Mid-level troughing across the Pacific Northwest is expected to begin translating northeastward along the northern periphery of the ridge by Day 5/Wednesday, inviting drier conditions to filter into the Northwestern U.S. Ridge positioning will also usher in a northward surge of elevated monsoon moisture into the Desert Southwest by Day 4/Tuesday and by Day 5/Wednesday across the Eastern Great Basin. A dry boundary layer in place across the Four Corners and Great Basin regions will support limited rainfall from higher terrain convection and thunderstorms. Fuels are expected to remain quite dry and receptive across this region with a particular threat from new lightning ignitions. A 10 percent probability area for dry thunderstorms was introduced for Day 5/Wednesday. Farther north, the mid-level trough could support additional thunderstorms across portions of the central/northern ID and western MT Day 4-5/Tuesday-Wednesday but some uncertainty regarding antecedent rainfall distribution along with marginal fuel dryness precludes introduction of dry thunderstorm probabilities at this time. ...Day 6-8/Thursday-Saturday... Deeper monsoon moisture moving into Great Basin, with PWATs around 1.00 inch as well as rising surface dewpoints/relative humidity, should begin to limit dry lightning potential late in the week across the Great Basin and Four Corners regions with at least some wetting rains expected. Nonetheless, multiple days of higher terrain showers and thunderstorms will expand across much of the Intermountain West late next week. Lighter winds overall are expected under a building ridge over the Western U.S. along with steadily increasing temperatures, particularly across the western coastal states. A thermal trough begins to set up across CA late next week, further drying fuelscapes across the region as temperatures reach into the 100s in valley/interior locations. ..Williams.. 08/16/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0458 PM CDT Sat Aug 16 2025 Valid 181200Z - 241200Z ...Day 3-5/Monday-Wednesday... An expanding and strengthening mid-level ridge over the Four Corners region will bring above normal temperatures but relatively light winds to much of the Intermountain West through the midweek. Mid-level troughing across the Pacific Northwest is expected to begin translating northeastward along the northern periphery of the ridge by Day 5/Wednesday, inviting drier conditions to filter into the Northwestern U.S. Ridge positioning will also usher in a northward surge of elevated monsoon moisture into the Desert Southwest by Day 4/Tuesday and by Day 5/Wednesday across the Eastern Great Basin. A dry boundary layer in place across the Four Corners and Great Basin regions will support limited rainfall from higher terrain convection and thunderstorms. Fuels are expected to remain quite dry and receptive across this region with a particular threat from new lightning ignitions. A 10 percent probability area for dry thunderstorms was introduced for Day 5/Wednesday. Farther north, the mid-level trough could support additional thunderstorms across portions of the central/northern ID and western MT Day 4-5/Tuesday-Wednesday but some uncertainty regarding antecedent rainfall distribution along with marginal fuel dryness precludes introduction of dry thunderstorm probabilities at this time. ...Day 6-8/Thursday-Saturday... Deeper monsoon moisture moving into Great Basin, with PWATs around 1.00 inch as well as rising surface dewpoints/relative humidity, should begin to limit dry lightning potential late in the week across the Great Basin and Four Corners regions with at least some wetting rains expected. Nonetheless, multiple days of higher terrain showers and thunderstorms will expand across much of the Intermountain West late next week. Lighter winds overall are expected under a building ridge over the Western U.S. along with steadily increasing temperatures, particularly across the western coastal states. A thermal trough begins to set up across CA late next week, further drying fuelscapes across the region as temperatures reach into the 100s in valley/interior locations. ..Williams.. 08/16/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0458 PM CDT Sat Aug 16 2025 Valid 181200Z - 241200Z ...Day 3-5/Monday-Wednesday... An expanding and strengthening mid-level ridge over the Four Corners region will bring above normal temperatures but relatively light winds to much of the Intermountain West through the midweek. Mid-level troughing across the Pacific Northwest is expected to begin translating northeastward along the northern periphery of the ridge by Day 5/Wednesday, inviting drier conditions to filter into the Northwestern U.S. Ridge positioning will also usher in a northward surge of elevated monsoon moisture into the Desert Southwest by Day 4/Tuesday and by Day 5/Wednesday across the Eastern Great Basin. A dry boundary layer in place across the Four Corners and Great Basin regions will support limited rainfall from higher terrain convection and thunderstorms. Fuels are expected to remain quite dry and receptive across this region with a particular threat from new lightning ignitions. A 10 percent probability area for dry thunderstorms was introduced for Day 5/Wednesday. Farther north, the mid-level trough could support additional thunderstorms across portions of the central/northern ID and western MT Day 4-5/Tuesday-Wednesday but some uncertainty regarding antecedent rainfall distribution along with marginal fuel dryness precludes introduction of dry thunderstorm probabilities at this time. ...Day 6-8/Thursday-Saturday... Deeper monsoon moisture moving into Great Basin, with PWATs around 1.00 inch as well as rising surface dewpoints/relative humidity, should begin to limit dry lightning potential late in the week across the Great Basin and Four Corners regions with at least some wetting rains expected. Nonetheless, multiple days of higher terrain showers and thunderstorms will expand across much of the Intermountain West late next week. Lighter winds overall are expected under a building ridge over the Western U.S. along with steadily increasing temperatures, particularly across the western coastal states. A thermal trough begins to set up across CA late next week, further drying fuelscapes across the region as temperatures reach into the 100s in valley/interior locations. ..Williams.. 08/16/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 3-8 Fire Weather Outlook
Day 3-8 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0458 PM CDT Sat Aug 16 2025 Valid 181200Z - 241200Z ...Day 3-5/Monday-Wednesday... An expanding and strengthening mid-level ridge over the Four Corners region will bring above normal temperatures but relatively light winds to much of the Intermountain West through the midweek. Mid-level troughing across the Pacific Northwest is expected to begin translating northeastward along the northern periphery of the ridge by Day 5/Wednesday, inviting drier conditions to filter into the Northwestern U.S. Ridge positioning will also usher in a northward surge of elevated monsoon moisture into the Desert Southwest by Day 4/Tuesday and by Day 5/Wednesday across the Eastern Great Basin. A dry boundary layer in place across the Four Corners and Great Basin regions will support limited rainfall from higher terrain convection and thunderstorms. Fuels are expected to remain quite dry and receptive across this region with a particular threat from new lightning ignitions. A 10 percent probability area for dry thunderstorms was introduced for Day 5/Wednesday. Farther north, the mid-level trough could support additional thunderstorms across portions of the central/northern ID and western MT Day 4-5/Tuesday-Wednesday but some uncertainty regarding antecedent rainfall distribution along with marginal fuel dryness precludes introduction of dry thunderstorm probabilities at this time. ...Day 6-8/Thursday-Saturday... Deeper monsoon moisture moving into Great Basin, with PWATs around 1.00 inch as well as rising surface dewpoints/relative humidity, should begin to limit dry lightning potential late in the week across the Great Basin and Four Corners regions with at least some wetting rains expected. Nonetheless, multiple days of higher terrain showers and thunderstorms will expand across much of the Intermountain West late next week. Lighter winds overall are expected under a building ridge over the Western U.S. along with steadily increasing temperatures, particularly across the western coastal states. A thermal trough begins to set up across CA late next week, further drying fuelscapes across the region as temperatures reach into the 100s in valley/interior locations. ..Williams.. 08/16/2025 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

Issued at 2100 UTC SAT AUG 16 2025 286 FONT15 KNHC 162128 PWSAT5 HURRICANE ERIN WIND SPEED PROBABILITIES NUMBER 22...RESENT NWS NATIONAL HURRICANE CENTER MIAMI FL AL052025 2100 UTC SAT AUG 16 2025 AT 2100Z THE CENTER OF HURRICANE ERIN WAS LOCATED NEAR LATITUDE 20.0 NORTH...LONGITUDE 64.0 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 140 KTS...160 MPH...260 KM/H. Z INDICATES COORDINATED UNIVERSAL TIME (GREENWICH) ATLANTIC STANDARD TIME (AST)...SUBTRACT 4 HOURS FROM Z TIME EASTERN DAYLIGHT TIME (EDT)...SUBTRACT 4 HOURS FROM Z TIME CENTRAL DAYLIGHT TIME (CDT)...SUBTRACT 5 HOURS FROM Z TIME WIND SPEED PROBABILITY TABLE FOR SPECIFIC LOCATIONS CHANCES OF SUSTAINED (1-MINUTE AVERAGE) WIND SPEEDS OF AT LEAST ...34 KT (39 MPH... 63 KM/H)... ...50 KT (58 MPH... 93 KM/H)... ...64 KT (74 MPH...119 KM/H)... FOR LOCATIONS AND TIME PERIODS DURING THE NEXT 5 DAYS PROBABILITIES FOR LOCATIONS ARE GIVEN AS OP(CP) WHERE OP IS THE PROBABILITY OF THE EVENT BEGINNING DURING AN INDIVIDUAL TIME PERIOD (ONSET PROBABILITY) (CP) IS THE PROBABILITY OF THE EVENT OCCURRING BETWEEN 18Z SAT AND THE FORECAST HOUR (CUMULATIVE PROBABILITY) PROBABILITIES ARE GIVEN IN PERCENT X INDICATES PROBABILITIES LESS THAN 1 PERCENT PROBABILITIES FOR 34 KT AND 50 KT ARE SHOWN AT A GIVEN LOCATION WHEN THE 5-DAY CUMULATIVE PROBABILITY IS AT LEAST 3 PERCENT. PROBABILITIES FOR 34...50...64 KT SHOWN WHEN THE 5-DAY 64-KT CUMULATIVE PROBABILITY IS AT LEAST 1 PERCENT. - - - - WIND SPEED PROBABILITIES FOR SELECTED LOCATIONS - - - - FROM FROM FROM FROM FROM FROM FROM TIME 18Z SAT 06Z SUN 18Z SUN 06Z MON 18Z MON 18Z TUE 18Z WED PERIODS TO TO TO TO TO TO TO 06Z SUN 18Z SUN 06Z MON 18Z MON 18Z TUE 18Z WED 18Z THU FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT SABLE ISLAND 34 X X( X) X( X) X( X) X( X) X( X) 5( 5) YARMOUTH NS 34 X X( X) X( X) X( X) X( X) X( X) 5( 5) HYANNIS MA 34 X X( X) X( X) X( X) X( X) X( X) 3( 3) NANTUCKET MA 34 X X( X) X( X) X( X) X( X) X( X) 7( 7) NANTUCKET MA 50 X X( X) X( X) X( X) X( X) X( X) 2( 2) NANTUCKET MA 64 X X( X) X( X) X( X) X( X) X( X) 1( 1) PROVIDENCE RI 34 X X( X) X( X) X( X) X( X) X( X) 4( 4) MONTAUK POINT 34 X X( X) X( X) X( X) X( X) X( X) 4( 4) NYC JFK AIRPRT 34 X X( X) X( X) X( X) X( X) X( X) 3( 3) CAPE HENLOPEN 34 X X( X) X( X) X( X) X( X) X( X) 3( 3) OCEAN CITY MD 34 X X( X) X( X) X( X) X( X) 1( 1) 3( 4) WALLOPS CDA 34 X X( X) X( X) X( X) X( X) 1( 1) 3( 4) NORFOLK VA 34 X X( X) X( X) X( X) X( X) 1( 1) 2( 3) OCEANA NAS VA 34 X X( X) X( X) X( X) X( X) 2( 2) 3( 5) ELIZABETH CTY 34 X X( X) X( X) X( X) X( X) 2( 2) 1( 3) CAPE HATTERAS 34 X X( X) X( X) X( X) X( X) 7( 7) 4(11) CAPE HATTERAS 50 X X( X) X( X) X( X) X( X) 1( 1) 1( 2) CAPE HATTERAS 64 X X( X) X( X) X( X) X( X) 1( 1) X( 1) CHERRY PT NC 34 X X( X) X( X) X( X) X( X) 2( 2) 1( 3) MOREHEAD CITY 34 X X( X) X( X) X( X) X( X) 5( 5) 2( 7) SURF CITY NC 34 X X( X) X( X) X( X) X( X) 3( 3) 1( 4) BALD HEAD ISL 34 X X( X) X( X) X( X) X( X) 3( 3) 1( 4) LITTLE RIVER 34 X X( X) X( X) X( X) X( X) 2( 2) 1( 3) BERMUDA 34 X X( X) X( X) X( X) X( X) 9( 9) 22(31) BERMUDA 50 X X( X) X( X) X( X) X( X) 1( 1) 8( 9) BERMUDA 64 X X( X) X( X) X( X) X( X) X( X) 4( 4) NEW PROVIDENCE 34 X X( X) X( X) X( X) 2( 2) X( 2) 1( 3) GREAT EXUMA 34 X X( X) X( X) 2( 2) 4( 6) X( 6) X( 6) SAN SALVADOR 34 X X( X) 1( 1) 5( 6) 10(16) 2(18) X(18) SAN SALVADOR 50 X X( X) X( X) X( X) 3( 3) X( 3) X( 3) SAN SALVADOR 64 X X( X) X( X) X( X) 1( 1) X( 1) X( 1) MAYAGUANA 34 X 1( 1) 4( 5) 9(14) 5(19) 1(20) X(20) MAYAGUANA 50 X X( X) 1( 1) 1( 2) 1( 3) 1( 4) X( 4) MAYAGUANA 64 X X( X) X( X) X( X) 1( 1) X( 1) X( 1) GRAND TURK 34 X 3( 3) 17(20) 9(29) 3(32) X(32) X(32) GRAND TURK 50 X X( X) 4( 4) 3( 7) 1( 8) X( 8) X( 8) GRAND TURK 64 X X( X) 1( 1) 1( 2) 1( 3) X( 3) X( 3) PUERTO PLATA 34 1 2( 3) 4( 7) 2( 9) 1(10) X(10) X(10) SANTO DOMINGO 34 1 2( 3) 2( 5) 1( 6) X( 6) X( 6) X( 6) PONCE PR 34 2 2( 4) 1( 5) X( 5) X( 5) X( 5) X( 5) AGUADILLA PR 34 2 3( 5) 1( 6) X( 6) X( 6) X( 6) X( 6) SAN JUAN PR 34 2 1( 3) 1( 4) X( 4) X( 4) X( 4) X( 4) VIEQUES PR 34 3 2( 5) X( 5) X( 5) X( 5) X( 5) X( 5) SAINT THOMAS 34 3 2( 5) X( 5) X( 5) X( 5) X( 5) X( 5) SAINT JOHN 34 3 1( 4) X( 4) X( 4) X( 4) X( 4) X( 4) SAINT CROIX 34 2 1( 3) X( 3) X( 3) X( 3) X( 3) X( 3) $$ FORECASTER BEVEN

Issued at 2100 UTC SAT AUG 16 2025 470 WTNT25 KNHC 162127 TCMAT5 HURRICANE ERIN FORECAST/ADVISORY NUMBER 22...RESENT NWS NATIONAL HURRICANE CENTER MIAMI FL AL052025 2100 UTC SAT AUG 16 2025 HURRICANE CENTER LOCATED NEAR 20.0N 64.0W AT 16/2100Z POSITION ACCURATE WITHIN 20 NM PRESENT MOVEMENT TOWARD THE WEST OR 280 DEGREES AT 13 KT ESTIMATED MINIMUM CENTRAL PRESSURE 915 MB EYE DIAMETER 5 NM MAX SUSTAINED WINDS 140 KT WITH GUSTS TO 170 KT. 64 KT....... 25NE 20SE 15SW 20NW. 50 KT....... 50NE 30SE 20SW 40NW. 34 KT.......140NE 90SE 40SW 110NW. 4 M SEAS....240NE 150SE 120SW 180NW. WINDS AND SEAS VARY GREATLY IN EACH QUADRANT. RADII IN NAUTICAL MILES ARE THE LARGEST RADII EXPECTED ANYWHERE IN THAT QUADRANT. REPEAT...CENTER LOCATED NEAR 20.0N 64.0W AT 16/2100Z AT 16/1800Z CENTER WAS LOCATED NEAR 19.8N 63.4W FORECAST VALID 17/0600Z 20.4N 65.7W MAX WIND 140 KT...GUSTS 170 KT. 64 KT... 25NE 20SE 15SW 25NW. 50 KT... 60NE 40SE 30SW 40NW. 34 KT...140NE 90SE 60SW 110NW. FORECAST VALID 17/1800Z 21.4N 67.6W MAX WIND 140 KT...GUSTS 170 KT. 64 KT... 30NE 25SE 20SW 30NW. 50 KT... 70NE 60SE 40SW 50NW. 34 KT...150NE 120SE 90SW 130NW. FORECAST VALID 18/0600Z 22.7N 69.2W MAX WIND 135 KT...GUSTS 165 KT. 64 KT... 40NE 30SE 25SW 35NW. 50 KT... 80NE 70SE 50SW 60NW. 34 KT...150NE 140SE 110SW 150NW. FORECAST VALID 18/1800Z 24.0N 70.2W MAX WIND 130 KT...GUSTS 160 KT. 64 KT... 50NE 40SE 30SW 40NW. 50 KT... 90NE 80SE 60SW 70NW. 34 KT...160NE 150SE 120SW 150NW. FORECAST VALID 19/0600Z 25.5N 70.9W MAX WIND 125 KT...GUSTS 150 KT. 64 KT... 60NE 60SE 40SW 40NW. 50 KT...100NE 90SE 70SW 70NW. 34 KT...170NE 160SE 140SW 160NW. FORECAST VALID 19/1800Z 27.3N 71.3W MAX WIND 120 KT...GUSTS 145 KT. 64 KT... 70NE 70SE 50SW 50NW. 50 KT...100NE 100SE 80SW 80NW. 34 KT...180NE 180SE 150SW 160NW. EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 125 NM ON DAY 4 AND 175 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY OUTLOOK VALID 20/1800Z 31.7N 70.8W MAX WIND 110 KT...GUSTS 135 KT. 50 KT...120NE 130SE 100SW 90NW. 34 KT...210NE 230SE 180SW 180NW. OUTLOOK VALID 21/1800Z 36.8N 65.0W MAX WIND 100 KT...GUSTS 120 KT. 50 KT...120NE 140SE 120SW 100NW. 34 KT...240NE 270SE 210SW 200NW. REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 20.0N 64.0W INTERMEDIATE PUBLIC ADVISORY...WTNT35 KNHC/MIATCPAT5...AT 17/0000Z NEXT ADVISORY AT 17/0300Z $$ FORECASTER BEVEN

MD 1966 CONCERNING SEVERE THUNDERSTORM WATCH 596... FOR SOUTHEAST WISCONSIN...NORTHEAST ILLINOIS...AND NORTHWEST INDIANA
Mesoscale Discussion 1966 NWS Storm Prediction Center Norman OK 0234 PM CDT Sat Aug 16 2025 Areas affected...southeast Wisconsin...northeast Illinois...and northwest Indiana Concerning...Severe Thunderstorm Watch 596... Valid 161934Z - 162100Z The severe weather threat for Severe Thunderstorm Watch 596 continues. SUMMARY...The severe weather threat is increasing through the afternoon. DISCUSSION...A cluster of supercells has developed across central Minnesota. The MKX VWP is sampling around 45 knots of mid-level flow which is resulting in around 40 knots of effective shear. Shear decreases rapidly with southern extent to only around 15 to 20 knots across northern Illinois. Therefore, storms may become less organized and outflow dominant as they congeal and move south across northern Illinois. However, greater instability (3000-4000 J/kg MLCAPE) and near 2 inch PWAT values will support a damaging wind threat as the storm cluster moves south this afternoon and evening. ..Bentley/Mosier.. 08/16/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...IWX...LOT...MKX...DVN... LAT...LON 42908961 43088920 43088827 42948766 42628728 42018704 41668691 41358689 41178707 41188772 41328848 41568885 42068936 42388951 42908961 MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN Read more

WW 0596 Status Updates
STATUS REPORT ON WW 596 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..BENTLEY..08/16/25 ATTN...WFO...LOT...DVN...MKX... STATUS REPORT FOR WS 596 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC007-031-037-043-089-093-097-111-141-177-197-201-162140- IL . ILLINOIS COUNTIES INCLUDED ARE BOONE COOK DE KALB DUPAGE KANE KENDALL LAKE MCHENRY OGLE STEPHENSON WILL WINNEBAGO INC089-127-162140- IN . INDIANA COUNTIES INCLUDED ARE LAKE PORTER WIC021-025-027-039-045-047-049-055-059-065-077-079-101-105-111- 127-133-162140- WI . WISCONSIN COUNTIES INCLUDED ARE COLUMBIA DANE DODGE Read more

WW 0596 Status Updates
STATUS REPORT ON WW 596 THE SEVERE WEATHER THREAT CONTINUES ACROSS THE ENTIRE WATCH AREA. ..BENTLEY..08/16/25 ATTN...WFO...LOT...DVN...MKX... STATUS REPORT FOR WS 596 SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS ILC007-031-037-043-089-093-097-111-141-177-197-201-162140- IL . ILLINOIS COUNTIES INCLUDED ARE BOONE COOK DE KALB DUPAGE KANE KENDALL LAKE MCHENRY OGLE STEPHENSON WILL WINNEBAGO INC089-127-162140- IN . INDIANA COUNTIES INCLUDED ARE LAKE PORTER WIC021-025-027-039-045-047-049-055-059-065-077-079-101-105-111- 127-133-162140- WI . WISCONSIN COUNTIES INCLUDED ARE COLUMBIA DANE DODGE Read more

Issued at 500 PM AST Sat Aug 16 2025 219 WTNT45 KNHC 162043 TCDAT5 Hurricane Erin Discussion Number 22 NWS National Hurricane Center Miami FL AL052025 500 PM AST Sat Aug 16 2025 Erin's rapid intensification may have bottomed out near 16Z based on the last couple of passes of data from an Air Force Reserve Hurricane Hunter. At that time, the maximum winds were near 140 kt and the central pressure was near 915 mb. Both Air Force and NOAA aircraft reported concentric eyewalls forming, and during the last couple of hours the small eye seen in conventional satellite imagery is becoming cloud-filled. This suggests an eyewall replacement cycle may be starting. The initial intensity is held at 140 kt pending the upcoming arrival of a NOAA Hurricane Hunter. The eye has started to gain latitude during the past few hours and the initial motion is now 280/13 kt - a little slower than before. The track guidance still suggests that Erin will turn back to the west-northwest with a decrease in forward speed during the next 6-12 h on the south side of a subtropical ridge. This motion should then continue through 24-36 h. After 36 h, the western side of the ridge is still expected to weaken, due to a series of shortwave troughs moving through the mid-latitude westerlies, and that should cause Erin to slow further and make a gradual turn to the north. However, there remains a significant spread in the guidance in just when this turn will occur, and the spread has increased due to the 12Z ECMWF forecast shifting to the west. Overall, the guidance envelope has shifted to the left during the entire forecast track, and the new forecast track is also shifted to the west. The new track is still to the east of the consensus models during the northward motion, and additional track adjustments may be necessary in later forecasts. Fluctuations in intensity are expected during the next 24 hours due to possible eyewall replacement cycles. However, Erin should remain a strong hurricane during this time. Between 24-72 h, increasing northwesterly shear should cause a gradual weakening, although there are likely to be fluctuations superimposed on this. After 72 h, the storm should start to encounter the mid-latitude westerlies where the shear will increase further. The new intensity forecast will show an increased weakening rate, but will keep Erin as a major hurricane as it will still be over warm sea surface temperatures during that time. Although Erin is a somewhat compact hurricane now, the models are in strong agreement that the system will grow in size over the next several days. In fact, by the middle of next week, Erin is forecast to at least double or triple in size, which will result in rough ocean conditions over the western Atlantic. KEY MESSAGES: 1. Heavy rainfall at times through Sunday across the northern Leeward Islands, the Virgin Islands, and Puerto Rico may lead to locally considerable flash and urban flooding, along with landslides or mudslides. 2. Tropical-storm conditions are possible in the Turks and Caicos Islands during the next 48 h, where a Tropical Storm Watch is now in effect. Gusts to tropical storm force in Erin's outer rainbands are likely in portions of the northern Leeward Islands through tonight and over portions of the Virgin Islands and Puerto Rico through Sunday. Tropical-storm force wind gusts are possible in the Southeast Bahamas beginning on Sunday. 3. Erin is expected to produce life-threatening surf and rip currents along the beaches of the Bahamas, much of the east coast of the U.S., and Atlantic Canada next week. 4. Interests in Bermuda should continue to monitor the progress of Erin since there is a risk of strong winds, heavy rainfall, and high surf by the middle part of next week. FORECAST POSITIONS AND MAX WINDS INIT 16/2100Z 20.0N 64.0W 140 KT 160 MPH 12H 17/0600Z 20.4N 65.7W 140 KT 160 MPH 24H 17/1800Z 21.4N 67.6W 140 KT 160 MPH 36H 18/0600Z 22.7N 69.2W 135 KT 155 MPH 48H 18/1800Z 24.0N 70.2W 130 KT 150 MPH 60H 19/0600Z 25.5N 70.9W 125 KT 145 MPH 72H 19/1800Z 27.3N 71.3W 120 KT 140 MPH 96H 20/1800Z 31.7N 70.8W 110 KT 125 MPH 120H 21/1800Z 36.8N 65.0W 100 KT 115 MPH $$ Forecaster Beven

MD 1965 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR NORTHEAST IOWA...SOUTHEAST MINNESOTA AND WESTERN WISCONSIN.
Mesoscale Discussion 1965 NWS Storm Prediction Center Norman OK 0205 PM CDT Sat Aug 16 2025 Areas affected...northeast Iowa...southeast Minnesota and western Wisconsin. Concerning...Severe potential...Watch unlikely Valid 161905Z - 162030Z Probability of Watch Issuance...20 percent SUMMARY...Isolated severe storms are possible this afternoon/evening. No watch is anticipated. DISCUSSION...A cluster of storms has developed across southeast Minnesota and western Wisconsin in the wake of the morning MCS. These elevated storms are in a region with strong shear (50+ knots per ARX VWP), but are somewhat removed from the better elevated instability according to SPC mesoanalysis. Therefore, the current location and storm motion favoring movement farther into the cold air would suggest severe potential may be somewhat limited from this activity. If additional storms can develop farther south (across northeast Iowa), they may pose a greater severe potential, but visible satellite trends do not support an imminent threat of additional development in this area. ..Bentley.. 08/16/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...GRB...MKX...ARX...MPX...DMX... LAT...LON 44409206 44419092 44719027 44718994 44388950 43798922 43368939 43099022 42889121 42889230 43059311 43529328 44409206 MOST PROBABLE PEAK WIND GUST...UP TO 60 MPH MOST PROBABLE PEAK HAIL SIZE...UP TO 1.25 IN Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 16 2025 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL... ...SUMMARY... Scattered strong/severe thunderstorms are possible today into tonight across parts of the northern Great Plains into the Midwest and Great Lakes regions. ...20Z Update... The prior forecast reasoning remains valid. Severe probabilities were reduced in parts of northern/central Wisconsin where prior convection has stabilized the boundary layer. Elsewhere, only minor changes were made to the general thunderstorm forecast based on current observational trends. See the previous discussion as well as MCDs 1965/1966 for additional information. ..Wendt.. 08/16/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/ ...Upper Midwest into the Mid MS Valley and Upper Great Lakes Region... An expansive MCS continues to move eastward across the Upper Midwest, with a well-defined MCV evident in radar imagery over the central WI/MN border vicinity. This MCS has continued to gradually weaken throughout the morning, but a few strong updrafts persist along its southeastern periphery over central WI. This portion of the MCS is on the far northeastern periphery of the plume of steeper mid-level lapse rates that extends from the northern/central High Plains across the central Plains and into the Mid MS Valley. This plume is observable in the 12Z sounding from DVN and ILX, which sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km, respectively. Dewpoints downstream across southern WI, northern IL, and northern IN are in the low 70s, with upper 60s dewpoints also covering much of southern Lower MI. The combination of ample low-level moisture and steep mid-level lapse rates will result in strong to very strong buoyancy to the south of the MCS from the MN/IA border into northern/central IL. Given the lack of a well-defined surface boundary and negligible large-scale ascent, additional thunderstorm development will be associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample moisture and buoyancy downstream of the leading edge of the MCS suggests the greater severe potential this afternoon/evening will likely be associated with redevelopment/reintensification of the MCS. Additionally, even if reintensification does not occur along the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern periphery of the MCV circulation as it moves into northern/central WI. Increased severe-wind probabilities (i.e. 15%) were introduced with this outlook to cover both of these potential scenarios. A small 15% hail probability was introduce to cover potential for later evening storms atop the outflow as well. Storms are possible into northern IN and the Lower MI this afternoon and evening as well, but the lower buoyancy should temper the overall coverage and magnitude in these areas. ...SD and Vicinity... A well-defined but rather weak shortwave trough is currently moving through western CO/western WY, and will continue northeastward into eastern WY/western Dakotas by this evening. Similar to yesterday, high-based storms will develop ahead of the approaching shortwave and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD. Upscale growth into another nocturnal MCS is forecast by most guidance, with the MCS tracking northeastward across western/central SD tonight. Strong to severe gusts are possible with this potential MCS across much of western/central SD. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 16 2025 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL... ...SUMMARY... Scattered strong/severe thunderstorms are possible today into tonight across parts of the northern Great Plains into the Midwest and Great Lakes regions. ...20Z Update... The prior forecast reasoning remains valid. Severe probabilities were reduced in parts of northern/central Wisconsin where prior convection has stabilized the boundary layer. Elsewhere, only minor changes were made to the general thunderstorm forecast based on current observational trends. See the previous discussion as well as MCDs 1965/1966 for additional information. ..Wendt.. 08/16/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/ ...Upper Midwest into the Mid MS Valley and Upper Great Lakes Region... An expansive MCS continues to move eastward across the Upper Midwest, with a well-defined MCV evident in radar imagery over the central WI/MN border vicinity. This MCS has continued to gradually weaken throughout the morning, but a few strong updrafts persist along its southeastern periphery over central WI. This portion of the MCS is on the far northeastern periphery of the plume of steeper mid-level lapse rates that extends from the northern/central High Plains across the central Plains and into the Mid MS Valley. This plume is observable in the 12Z sounding from DVN and ILX, which sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km, respectively. Dewpoints downstream across southern WI, northern IL, and northern IN are in the low 70s, with upper 60s dewpoints also covering much of southern Lower MI. The combination of ample low-level moisture and steep mid-level lapse rates will result in strong to very strong buoyancy to the south of the MCS from the MN/IA border into northern/central IL. Given the lack of a well-defined surface boundary and negligible large-scale ascent, additional thunderstorm development will be associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample moisture and buoyancy downstream of the leading edge of the MCS suggests the greater severe potential this afternoon/evening will likely be associated with redevelopment/reintensification of the MCS. Additionally, even if reintensification does not occur along the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern periphery of the MCV circulation as it moves into northern/central WI. Increased severe-wind probabilities (i.e. 15%) were introduced with this outlook to cover both of these potential scenarios. A small 15% hail probability was introduce to cover potential for later evening storms atop the outflow as well. Storms are possible into northern IN and the Lower MI this afternoon and evening as well, but the lower buoyancy should temper the overall coverage and magnitude in these areas. ...SD and Vicinity... A well-defined but rather weak shortwave trough is currently moving through western CO/western WY, and will continue northeastward into eastern WY/western Dakotas by this evening. Similar to yesterday, high-based storms will develop ahead of the approaching shortwave and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD. Upscale growth into another nocturnal MCS is forecast by most guidance, with the MCS tracking northeastward across western/central SD tonight. Strong to severe gusts are possible with this potential MCS across much of western/central SD. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 16 2025 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL... ...SUMMARY... Scattered strong/severe thunderstorms are possible today into tonight across parts of the northern Great Plains into the Midwest and Great Lakes regions. ...20Z Update... The prior forecast reasoning remains valid. Severe probabilities were reduced in parts of northern/central Wisconsin where prior convection has stabilized the boundary layer. Elsewhere, only minor changes were made to the general thunderstorm forecast based on current observational trends. See the previous discussion as well as MCDs 1965/1966 for additional information. ..Wendt.. 08/16/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/ ...Upper Midwest into the Mid MS Valley and Upper Great Lakes Region... An expansive MCS continues to move eastward across the Upper Midwest, with a well-defined MCV evident in radar imagery over the central WI/MN border vicinity. This MCS has continued to gradually weaken throughout the morning, but a few strong updrafts persist along its southeastern periphery over central WI. This portion of the MCS is on the far northeastern periphery of the plume of steeper mid-level lapse rates that extends from the northern/central High Plains across the central Plains and into the Mid MS Valley. This plume is observable in the 12Z sounding from DVN and ILX, which sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km, respectively. Dewpoints downstream across southern WI, northern IL, and northern IN are in the low 70s, with upper 60s dewpoints also covering much of southern Lower MI. The combination of ample low-level moisture and steep mid-level lapse rates will result in strong to very strong buoyancy to the south of the MCS from the MN/IA border into northern/central IL. Given the lack of a well-defined surface boundary and negligible large-scale ascent, additional thunderstorm development will be associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample moisture and buoyancy downstream of the leading edge of the MCS suggests the greater severe potential this afternoon/evening will likely be associated with redevelopment/reintensification of the MCS. Additionally, even if reintensification does not occur along the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern periphery of the MCV circulation as it moves into northern/central WI. Increased severe-wind probabilities (i.e. 15%) were introduced with this outlook to cover both of these potential scenarios. A small 15% hail probability was introduce to cover potential for later evening storms atop the outflow as well. Storms are possible into northern IN and the Lower MI this afternoon and evening as well, but the lower buoyancy should temper the overall coverage and magnitude in these areas. ...SD and Vicinity... A well-defined but rather weak shortwave trough is currently moving through western CO/western WY, and will continue northeastward into eastern WY/western Dakotas by this evening. Similar to yesterday, high-based storms will develop ahead of the approaching shortwave and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD. Upscale growth into another nocturnal MCS is forecast by most guidance, with the MCS tracking northeastward across western/central SD tonight. Strong to severe gusts are possible with this potential MCS across much of western/central SD. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 16 2025 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL... ...SUMMARY... Scattered strong/severe thunderstorms are possible today into tonight across parts of the northern Great Plains into the Midwest and Great Lakes regions. ...20Z Update... The prior forecast reasoning remains valid. Severe probabilities were reduced in parts of northern/central Wisconsin where prior convection has stabilized the boundary layer. Elsewhere, only minor changes were made to the general thunderstorm forecast based on current observational trends. See the previous discussion as well as MCDs 1965/1966 for additional information. ..Wendt.. 08/16/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/ ...Upper Midwest into the Mid MS Valley and Upper Great Lakes Region... An expansive MCS continues to move eastward across the Upper Midwest, with a well-defined MCV evident in radar imagery over the central WI/MN border vicinity. This MCS has continued to gradually weaken throughout the morning, but a few strong updrafts persist along its southeastern periphery over central WI. This portion of the MCS is on the far northeastern periphery of the plume of steeper mid-level lapse rates that extends from the northern/central High Plains across the central Plains and into the Mid MS Valley. This plume is observable in the 12Z sounding from DVN and ILX, which sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km, respectively. Dewpoints downstream across southern WI, northern IL, and northern IN are in the low 70s, with upper 60s dewpoints also covering much of southern Lower MI. The combination of ample low-level moisture and steep mid-level lapse rates will result in strong to very strong buoyancy to the south of the MCS from the MN/IA border into northern/central IL. Given the lack of a well-defined surface boundary and negligible large-scale ascent, additional thunderstorm development will be associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample moisture and buoyancy downstream of the leading edge of the MCS suggests the greater severe potential this afternoon/evening will likely be associated with redevelopment/reintensification of the MCS. Additionally, even if reintensification does not occur along the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern periphery of the MCV circulation as it moves into northern/central WI. Increased severe-wind probabilities (i.e. 15%) were introduced with this outlook to cover both of these potential scenarios. A small 15% hail probability was introduce to cover potential for later evening storms atop the outflow as well. Storms are possible into northern IN and the Lower MI this afternoon and evening as well, but the lower buoyancy should temper the overall coverage and magnitude in these areas. ...SD and Vicinity... A well-defined but rather weak shortwave trough is currently moving through western CO/western WY, and will continue northeastward into eastern WY/western Dakotas by this evening. Similar to yesterday, high-based storms will develop ahead of the approaching shortwave and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD. Upscale growth into another nocturnal MCS is forecast by most guidance, with the MCS tracking northeastward across western/central SD tonight. Strong to severe gusts are possible with this potential MCS across much of western/central SD. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 16 2025 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL... ...SUMMARY... Scattered strong/severe thunderstorms are possible today into tonight across parts of the northern Great Plains into the Midwest and Great Lakes regions. ...20Z Update... The prior forecast reasoning remains valid. Severe probabilities were reduced in parts of northern/central Wisconsin where prior convection has stabilized the boundary layer. Elsewhere, only minor changes were made to the general thunderstorm forecast based on current observational trends. See the previous discussion as well as MCDs 1965/1966 for additional information. ..Wendt.. 08/16/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/ ...Upper Midwest into the Mid MS Valley and Upper Great Lakes Region... An expansive MCS continues to move eastward across the Upper Midwest, with a well-defined MCV evident in radar imagery over the central WI/MN border vicinity. This MCS has continued to gradually weaken throughout the morning, but a few strong updrafts persist along its southeastern periphery over central WI. This portion of the MCS is on the far northeastern periphery of the plume of steeper mid-level lapse rates that extends from the northern/central High Plains across the central Plains and into the Mid MS Valley. This plume is observable in the 12Z sounding from DVN and ILX, which sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km, respectively. Dewpoints downstream across southern WI, northern IL, and northern IN are in the low 70s, with upper 60s dewpoints also covering much of southern Lower MI. The combination of ample low-level moisture and steep mid-level lapse rates will result in strong to very strong buoyancy to the south of the MCS from the MN/IA border into northern/central IL. Given the lack of a well-defined surface boundary and negligible large-scale ascent, additional thunderstorm development will be associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample moisture and buoyancy downstream of the leading edge of the MCS suggests the greater severe potential this afternoon/evening will likely be associated with redevelopment/reintensification of the MCS. Additionally, even if reintensification does not occur along the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern periphery of the MCV circulation as it moves into northern/central WI. Increased severe-wind probabilities (i.e. 15%) were introduced with this outlook to cover both of these potential scenarios. A small 15% hail probability was introduce to cover potential for later evening storms atop the outflow as well. Storms are possible into northern IN and the Lower MI this afternoon and evening as well, but the lower buoyancy should temper the overall coverage and magnitude in these areas. ...SD and Vicinity... A well-defined but rather weak shortwave trough is currently moving through western CO/western WY, and will continue northeastward into eastern WY/western Dakotas by this evening. Similar to yesterday, high-based storms will develop ahead of the approaching shortwave and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD. Upscale growth into another nocturnal MCS is forecast by most guidance, with the MCS tracking northeastward across western/central SD tonight. Strong to severe gusts are possible with this potential MCS across much of western/central SD. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0257 PM CDT Sat Aug 16 2025 Valid 162000Z - 171200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL... ...SUMMARY... Scattered strong/severe thunderstorms are possible today into tonight across parts of the northern Great Plains into the Midwest and Great Lakes regions. ...20Z Update... The prior forecast reasoning remains valid. Severe probabilities were reduced in parts of northern/central Wisconsin where prior convection has stabilized the boundary layer. Elsewhere, only minor changes were made to the general thunderstorm forecast based on current observational trends. See the previous discussion as well as MCDs 1965/1966 for additional information. ..Wendt.. 08/16/2025 .PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/ ...Upper Midwest into the Mid MS Valley and Upper Great Lakes Region... An expansive MCS continues to move eastward across the Upper Midwest, with a well-defined MCV evident in radar imagery over the central WI/MN border vicinity. This MCS has continued to gradually weaken throughout the morning, but a few strong updrafts persist along its southeastern periphery over central WI. This portion of the MCS is on the far northeastern periphery of the plume of steeper mid-level lapse rates that extends from the northern/central High Plains across the central Plains and into the Mid MS Valley. This plume is observable in the 12Z sounding from DVN and ILX, which sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km, respectively. Dewpoints downstream across southern WI, northern IL, and northern IN are in the low 70s, with upper 60s dewpoints also covering much of southern Lower MI. The combination of ample low-level moisture and steep mid-level lapse rates will result in strong to very strong buoyancy to the south of the MCS from the MN/IA border into northern/central IL. Given the lack of a well-defined surface boundary and negligible large-scale ascent, additional thunderstorm development will be associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample moisture and buoyancy downstream of the leading edge of the MCS suggests the greater severe potential this afternoon/evening will likely be associated with redevelopment/reintensification of the MCS. Additionally, even if reintensification does not occur along the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern periphery of the MCV circulation as it moves into northern/central WI. Increased severe-wind probabilities (i.e. 15%) were introduced with this outlook to cover both of these potential scenarios. A small 15% hail probability was introduce to cover potential for later evening storms atop the outflow as well. Storms are possible into northern IN and the Lower MI this afternoon and evening as well, but the lower buoyancy should temper the overall coverage and magnitude in these areas. ...SD and Vicinity... A well-defined but rather weak shortwave trough is currently moving through western CO/western WY, and will continue northeastward into eastern WY/western Dakotas by this evening. Similar to yesterday, high-based storms will develop ahead of the approaching shortwave and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD. Upscale growth into another nocturnal MCS is forecast by most guidance, with the MCS tracking northeastward across western/central SD tonight. Strong to severe gusts are possible with this potential MCS across much of western/central SD. Read more