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Issued at 300 PM MDT Sun Sep 01 2019 000 WTPZ41 KNHC 012041 TCDEP1 Tropical Storm Juliette Discussion Number 3 NWS National Hurricane Center Miami FL EP112019 300 PM MDT Sun Sep 01 2019 Juliette's presentation in visible satellite imagery has continued to improve, with hints of a banding eye now present. That said, the convection in the cyclone's bands is not that deep, and recent ASCAT data still supports an intensity of 50 kt. No change was made to the track forecast. The hurricane is moving northwest at 11 kt, steered primarily by a mid-level ridge centered over the southwestern US. All of the guidance shows that Juliette will move west-northwestward to northwestward for the next 3 days, with a slight decrease in forward speed. After that, differences in the forecasted strength of the ridge result in a larger model spread. The ECMWF shows Juliette turning nearly westward due to an amplification of the ridge, while the GFS forecasts that the ridge will weaken, causing Juliette to move farther north. The NHC forecast is nearly directly between those two models and lies very close to the model consensus at all forecast hours, but its worth noting that confidence in the track forecast is fairly low at 96 h and beyond. Low wind shear, a warm underlying ocean, and sufficient environmental moisture should allow Juliette to strengthen for the next 2-3 days. The largest uncertainty is the rate at which the tropical storm will strengthen, and the rapid intensification guidance is not quite as bullish as it was 6 hours ago. Subsequently, no major change was made to the intensity forecast, and Juliette is still expected to become a hurricane on Monday. By the end of the forecast, the cyclone will likely begin moving over cooler waters and through a far more stable environment. This should cause Juliette to weaken, particularly if it moves farther north than the NHC official forecast, as shown by the GFS. If Juliette takes a farther south track, like that of the ECMWF, it could maintain its intensity longer than currently forecast. FORECAST POSITIONS AND MAX WINDS INIT 01/2100Z 14.9N 109.7W 50 KT 60 MPH 12H 02/0600Z 15.9N 111.2W 60 KT 70 MPH 24H 02/1800Z 17.0N 113.1W 70 KT 80 MPH 36H 03/0600Z 17.9N 114.8W 85 KT 100 MPH 48H 03/1800Z 18.5N 116.3W 90 KT 105 MPH 72H 04/1800Z 19.5N 119.0W 85 KT 100 MPH 96H 05/1800Z 21.0N 122.5W 70 KT 80 MPH 120H 06/1800Z 23.0N 127.0W 50 KT 60 MPH $$ Forecaster Zelinsky

Issued at 2100 UTC SUN SEP 01 2019 000 FOPZ11 KNHC 012040 PWSEP1 TROPICAL STORM JULIETTE WIND SPEED PROBABILITIES NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL EP112019 2100 UTC SUN SEP 01 2019 AT 2100Z THE CENTER OF TROPICAL STORM JULIETTE WAS LOCATED NEAR LATITUDE 14.9 NORTH...LONGITUDE 109.7 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 50 KTS...60 MPH...95 KM/H. Z INDICATES COORDINATED UNIVERSAL TIME (GREENWICH) PACIFIC DAYLIGHT TIME (PDT)...SUBTRACT 7 HOURS FROM Z TIME HAWAIIAN STANDARD TIME (HST)...SUBTRACT 10 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 SUN 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 SUN 06Z MON 18Z MON 06Z TUE 18Z TUE 18Z WED 18Z THU PERIODS TO TO TO TO TO TO TO 06Z MON 18Z MON 06Z TUE 18Z TUE 18Z WED 18Z THU 18Z FRI FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT 15N 110W 34 99 X(99) X(99) X(99) X(99) X(99) X(99) 15N 110W 50 30 X(30) X(30) X(30) X(30) X(30) X(30) 15N 110W 64 2 X( 2) X( 2) X( 2) X( 2) X( 2) X( 2) 20N 110W 34 3 4( 7) 2( 9) 1(10) X(10) X(10) X(10) ISLA SOCORRO 34 10 14(24) 4(28) 2(30) X(30) X(30) X(30) ISLA CLARION 34 3 24(27) 58(85) 7(92) 1(93) X(93) X(93) ISLA CLARION 50 X 1( 1) 52(53) 18(71) 3(74) X(74) X(74) ISLA CLARION 64 X X( X) 26(26) 17(43) 1(44) X(44) X(44) 15N 115W 34 2 6( 8) 8(16) 3(19) 3(22) X(22) X(22) 20N 115W 34 X 7( 7) 27(34) 21(55) 5(60) 1(61) X(61) 20N 115W 50 X X( X) 3( 3) 12(15) 2(17) X(17) X(17) 20N 115W 64 X X( X) 1( 1) 4( 5) X( 5) X( 5) X( 5) 15N 120W 34 X X( X) 1( 1) 1( 2) 5( 7) 2( 9) X( 9) 20N 120W 34 X X( X) 1( 1) 5( 6) 47(53) 26(79) 1(80) 20N 120W 50 X X( X) X( X) X( X) 19(19) 24(43) 1(44) 20N 120W 64 X X( X) X( X) X( X) 8( 8) 15(23) X(23) 25N 120W 34 X X( X) X( X) X( X) 1( 1) 5( 6) 1( 7) 20N 125W 34 X X( X) X( X) X( X) 1( 1) 17(18) 16(34) 20N 125W 50 X X( X) X( X) X( X) X( X) 4( 4) 7(11) 20N 125W 64 X X( X) X( X) X( X) X( X) 1( 1) 4( 5) 25N 125W 34 X X( X) X( X) X( X) X( X) 4( 4) 15(19) 25N 125W 50 X X( X) X( X) X( X) X( X) X( X) 4( 4) 20N 130W 34 X X( X) X( X) X( X) X( X) X( X) 5( 5) 25N 130W 34 X X( X) X( X) X( X) X( X) X( X) 6( 6) $$ FORECASTER ZELINSKY

Issued at 300 PM MDT Sun Sep 01 2019 000 WTPZ31 KNHC 012040 TCPEP1 BULLETIN Tropical Storm Juliette Advisory Number 3 NWS National Hurricane Center Miami FL EP112019 300 PM MDT Sun Sep 01 2019 ...JULIETTE FORECAST TO BECOME A HURRICANE ON MONDAY... SUMMARY OF 300 PM MDT...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...14.9N 109.7W ABOUT 455 MI...735 KM SW OF MANZANILLO MEXICO ABOUT 555 MI...890 KM S OF THE SOUTHERN TIP OF BAJA CALIFORNIA MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/H PRESENT MOVEMENT...NW OR 310 DEGREES AT 13 MPH...20 KM/H MINIMUM CENTRAL PRESSURE...998 MB...29.47 INCHES WATCHES AND WARNINGS -------------------- There are no coastal watches or warnings in effect. DISCUSSION AND OUTLOOK ---------------------- At 300 PM MDT (2100 UTC), the center of Tropical Storm Juliette was located near latitude 14.9 North, longitude 109.7 West. Juliette is moving toward the northwest near 13 mph (20 km/h). A west-northwestward to northwestward motion with a slight decrease in forward speed is anticipated for the next several days. Maximum sustained winds are near 60 mph (95 km/h) with higher gusts. Strengthening is forecast, and Juliette is expected to become a hurricane on Monday. Tropical-storm-force winds extend outward up to 150 miles (240 km) from the center. The estimated minimum central pressure is 998 mb (29.47 inches). HAZARDS AFFECTING LAND ---------------------- None. NEXT ADVISORY ------------- Next complete advisory at 900 PM MDT. $$ Forecaster Zelinsky

...JULIETTE FORECAST TO BECOME A HURRICANE ON MONDAY... As of 3:00 PM MDT Sun Sep 1 the center of Juliette was located near 14.9, -109.7 with movement NW at 13 mph. The minimum central pressure was 998 mb with maximum sustained winds of about 60 mph.

Issued at 2100 UTC SUN SEP 01 2019 000 WTPZ21 KNHC 012039 TCMEP1 TROPICAL STORM JULIETTE FORECAST/ADVISORY NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL EP112019 2100 UTC SUN SEP 01 2019 THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT. TROPICAL STORM CENTER LOCATED NEAR 14.9N 109.7W AT 01/2100Z POSITION ACCURATE WITHIN 25 NM PRESENT MOVEMENT TOWARD THE NORTHWEST OR 310 DEGREES AT 11 KT ESTIMATED MINIMUM CENTRAL PRESSURE 998 MB MAX SUSTAINED WINDS 50 KT WITH GUSTS TO 60 KT. 50 KT....... 60NE 0SE 0SW 0NW. 34 KT.......120NE 130SE 0SW 100NW. 12 FT SEAS..150NE 120SE 30SW 60NW. 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 14.9N 109.7W AT 01/2100Z AT 01/1800Z CENTER WAS LOCATED NEAR 14.5N 109.1W FORECAST VALID 02/0600Z 15.9N 111.2W MAX WIND 60 KT...GUSTS 75 KT. 50 KT... 60NE 0SE 0SW 50NW. 34 KT...120NE 130SE 40SW 100NW. FORECAST VALID 02/1800Z 17.0N 113.1W MAX WIND 70 KT...GUSTS 85 KT. 64 KT... 25NE 20SE 0SW 20NW. 50 KT... 60NE 50SE 40SW 50NW. 34 KT...120NE 120SE 70SW 110NW. FORECAST VALID 03/0600Z 17.9N 114.8W MAX WIND 85 KT...GUSTS 105 KT. 64 KT... 30NE 25SE 20SW 20NW. 50 KT... 60NE 50SE 40SW 50NW. 34 KT...120NE 100SE 80SW 110NW. FORECAST VALID 03/1800Z 18.5N 116.3W MAX WIND 90 KT...GUSTS 110 KT. 64 KT... 30NE 25SE 20SW 25NW. 50 KT... 60NE 50SE 40SW 50NW. 34 KT...120NE 100SE 80SW 110NW. FORECAST VALID 04/1800Z 19.5N 119.0W MAX WIND 85 KT...GUSTS 105 KT. 50 KT... 50NE 40SE 40SW 40NW. 34 KT...110NE 90SE 70SW 100NW. EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 100 NM ON DAY 4 AND 150 NM ON DAY 5...AND FOR INTENSITY NEAR 15 KT EACH DAY OUTLOOK VALID 05/1800Z 21.0N 122.5W MAX WIND 70 KT...GUSTS 85 KT. OUTLOOK VALID 06/1800Z 23.0N 127.0W MAX WIND 50 KT...GUSTS 60 KT. REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 14.9N 109.7W NEXT ADVISORY AT 02/0300Z $$ FORECASTER ZELINSKY

MD 1906 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PARTS OF CENTRAL AND SOUTHERN ARIZONA
Mesoscale Discussion 1906 NWS Storm Prediction Center Norman OK 0334 PM CDT Sun Sep 01 2019 Areas affected...Parts of central and southern Arizona Concerning...Severe potential...Watch possible Valid 012034Z - 012230Z Probability of Watch Issuance...40 percent SUMMARY...Thunderstorms will continue to develop along the higher terrain of central and southeast Arizona this afternoon. Some of this will gradually consolidate, and may pose increasing risk for strong wind gusts, particularly south of the Mogollon Rim. It is not certain that a severe weather watch will be needed, but trends are being monitored for this possibility. DISCUSSION...Mid/upper support for convective development appears generally weak, but initiation of thunderstorm activity is ongoing, likely aided by daytime heating and orographic forcing along the Mogollon Rim and mountains of southeastern Arizona. Deep boundary layer mixing is also well underway across the lower deserts to the south and west, with sufficient moisture to support CAPE in excess of 1000 J/kg. Light deep-layer easterly ambient mean flow, with some enhancement at mid-levels, should at least contribute to some support for propagation of convection off the higher terrain, toward the lower deserts, through afternoon. This component seems strongest off the mountains of southeastern Arizona. However, the most substantive clustering of ongoing convection is currently along the Rim, south/southwest of Show Low. Within the next few hours, this may begin to produce increasing outflow advancing southwestward along and south of the Rim, where models suggest that the strongest low-level upslope flow component will become focused. This may be accompanied by continuing thunderstorm development and upscale convective growth, with increasing potential for localized strong downbursts, and strong wind gusts along the leading edge of the consolidating outflow. ..Kerr/Guyer.. 09/01/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...TWC...FGZ...PSR... LAT...LON 32301129 32591189 32761208 33371285 34141316 34641147 33740996 33240980 32811007 32341050 32301129 Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0246 PM CDT Sun Sep 01 2019 Valid 012000Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF CENTRAL AND SOUTHERN ARIZONA... ...SUMMARY... Scattered severe wind gusts are possible across parts of central and southern Arizona during the late afternoon and evening, with other severe storms possible across the northern High Plains and Ohio Valley. Little change was required to the previous outlook except to expand low tornado probabilities southwest to the Ohio River where significant low-level CAPE exists as per modified ILN 18Z sounding. Shear is weak, thus any rotation is expected to remain weak and short lived. ..Jewell.. 09/01/2019 .PREV DISCUSSION... /ISSUED 1131 AM CDT Sun Sep 01 2019/ ...Central/southern Arizona... The mid/upper-level ridge will remain centered over the Four Corners area through tonight, with a belt of moderately strong easterly mid-level winds on its immediate southern periphery as sampled by 12Z observed soundings from Phoenix/Tucson. Orographic lift will be the primary driver of isolated to widely scattered thunderstorms by early afternoon across the higher terrain of western New Mexico into central/eastern Arizona. With a belt of 15-25 kt easterlies across the southern half of Arizona, this convection will spread westward over the lower deserts during the late afternoon and evening. Surface dew points should mix into the upper 50s to mid 60s at peak heating across the Lower Colorado and Gila Valleys, yielding at least moderate buoyancy with MLCAPE above 1000 J/kg. One or two clusters may organize off the terrain with a risk for scattered severe-caliber wind gusts, with at least a couple of these storms likely to reach the Lower Colorado River Valley. ...Ohio Valley... A convectively influenced shortwave trough centered over central Indiana at late morning will continue east-northeastward toward the Upper Ohio Valley and western portions of Pennsylvania/New York. Modest ascent ahead of this feature will continue to influence thunderstorm development across the region, with some increase in coverage/intensity this afternoon as MLCAPE reaches 1000-1500 J/kg. The primary risks from multicell clusters should be isolated strong gusts and marginally severe hail. However, guidance is fairly consistent in strengthening low-level winds early this evening from the Upper Ohio Valley to northern Appalachians. A small temporal window may exist for a supercell-related brief tornado risk near the Ohio/Pennsylvania/West Virginia border area as low-level hodographs enlarge prior to surface-based instability decreasing with eastern extent in Pennsylvania. ...Northern High Plains including Montana to Nebraska... No changes warranted for the region. A mid-level ridge will remain prominent across much of the northern Great Plains through the period, although some flattening is anticipated towards 12Z/Monday as a vigorous shortwave trough amplifies over the Canadian Rockies. Isolated thunderstorms may develop along the lee trough from north-central Montana to the Nebraska/Colorado border area. Buoyancy will be weak to the northwest but may be compensated by plentiful mid to upper-level speed shear. A couple cells with mid-level updraft rotation may form but will likely struggle to be sustained eastward given pronounced MLCIN east of the trough. Have expanded/combined the MRGL risk areas to account for this scenario. Otherwise, an arc of 700-mb warm theta-e advection should yield isolated to perhaps scattered elevated thunderstorms overnight across eastern Montana and the Dakotas into Nebraska. Strongest speed shear will be across the northern portion of the region, with MUCAPE increasing as richer 850-mb moisture advects north. It is unclear whether uncapped parcels can become rooted beneath 700-mb prior to 12Z. For now, will maintain MRGL risk, mainly for the potential of isolated severe hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0246 PM CDT Sun Sep 01 2019 Valid 012000Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF CENTRAL AND SOUTHERN ARIZONA... ...SUMMARY... Scattered severe wind gusts are possible across parts of central and southern Arizona during the late afternoon and evening, with other severe storms possible across the northern High Plains and Ohio Valley. Little change was required to the previous outlook except to expand low tornado probabilities southwest to the Ohio River where significant low-level CAPE exists as per modified ILN 18Z sounding. Shear is weak, thus any rotation is expected to remain weak and short lived. ..Jewell.. 09/01/2019 .PREV DISCUSSION... /ISSUED 1131 AM CDT Sun Sep 01 2019/ ...Central/southern Arizona... The mid/upper-level ridge will remain centered over the Four Corners area through tonight, with a belt of moderately strong easterly mid-level winds on its immediate southern periphery as sampled by 12Z observed soundings from Phoenix/Tucson. Orographic lift will be the primary driver of isolated to widely scattered thunderstorms by early afternoon across the higher terrain of western New Mexico into central/eastern Arizona. With a belt of 15-25 kt easterlies across the southern half of Arizona, this convection will spread westward over the lower deserts during the late afternoon and evening. Surface dew points should mix into the upper 50s to mid 60s at peak heating across the Lower Colorado and Gila Valleys, yielding at least moderate buoyancy with MLCAPE above 1000 J/kg. One or two clusters may organize off the terrain with a risk for scattered severe-caliber wind gusts, with at least a couple of these storms likely to reach the Lower Colorado River Valley. ...Ohio Valley... A convectively influenced shortwave trough centered over central Indiana at late morning will continue east-northeastward toward the Upper Ohio Valley and western portions of Pennsylvania/New York. Modest ascent ahead of this feature will continue to influence thunderstorm development across the region, with some increase in coverage/intensity this afternoon as MLCAPE reaches 1000-1500 J/kg. The primary risks from multicell clusters should be isolated strong gusts and marginally severe hail. However, guidance is fairly consistent in strengthening low-level winds early this evening from the Upper Ohio Valley to northern Appalachians. A small temporal window may exist for a supercell-related brief tornado risk near the Ohio/Pennsylvania/West Virginia border area as low-level hodographs enlarge prior to surface-based instability decreasing with eastern extent in Pennsylvania. ...Northern High Plains including Montana to Nebraska... No changes warranted for the region. A mid-level ridge will remain prominent across much of the northern Great Plains through the period, although some flattening is anticipated towards 12Z/Monday as a vigorous shortwave trough amplifies over the Canadian Rockies. Isolated thunderstorms may develop along the lee trough from north-central Montana to the Nebraska/Colorado border area. Buoyancy will be weak to the northwest but may be compensated by plentiful mid to upper-level speed shear. A couple cells with mid-level updraft rotation may form but will likely struggle to be sustained eastward given pronounced MLCIN east of the trough. Have expanded/combined the MRGL risk areas to account for this scenario. Otherwise, an arc of 700-mb warm theta-e advection should yield isolated to perhaps scattered elevated thunderstorms overnight across eastern Montana and the Dakotas into Nebraska. Strongest speed shear will be across the northern portion of the region, with MUCAPE increasing as richer 850-mb moisture advects north. It is unclear whether uncapped parcels can become rooted beneath 700-mb prior to 12Z. For now, will maintain MRGL risk, mainly for the potential of isolated severe hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0246 PM CDT Sun Sep 01 2019 Valid 012000Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF CENTRAL AND SOUTHERN ARIZONA... ...SUMMARY... Scattered severe wind gusts are possible across parts of central and southern Arizona during the late afternoon and evening, with other severe storms possible across the northern High Plains and Ohio Valley. Little change was required to the previous outlook except to expand low tornado probabilities southwest to the Ohio River where significant low-level CAPE exists as per modified ILN 18Z sounding. Shear is weak, thus any rotation is expected to remain weak and short lived. ..Jewell.. 09/01/2019 .PREV DISCUSSION... /ISSUED 1131 AM CDT Sun Sep 01 2019/ ...Central/southern Arizona... The mid/upper-level ridge will remain centered over the Four Corners area through tonight, with a belt of moderately strong easterly mid-level winds on its immediate southern periphery as sampled by 12Z observed soundings from Phoenix/Tucson. Orographic lift will be the primary driver of isolated to widely scattered thunderstorms by early afternoon across the higher terrain of western New Mexico into central/eastern Arizona. With a belt of 15-25 kt easterlies across the southern half of Arizona, this convection will spread westward over the lower deserts during the late afternoon and evening. Surface dew points should mix into the upper 50s to mid 60s at peak heating across the Lower Colorado and Gila Valleys, yielding at least moderate buoyancy with MLCAPE above 1000 J/kg. One or two clusters may organize off the terrain with a risk for scattered severe-caliber wind gusts, with at least a couple of these storms likely to reach the Lower Colorado River Valley. ...Ohio Valley... A convectively influenced shortwave trough centered over central Indiana at late morning will continue east-northeastward toward the Upper Ohio Valley and western portions of Pennsylvania/New York. Modest ascent ahead of this feature will continue to influence thunderstorm development across the region, with some increase in coverage/intensity this afternoon as MLCAPE reaches 1000-1500 J/kg. The primary risks from multicell clusters should be isolated strong gusts and marginally severe hail. However, guidance is fairly consistent in strengthening low-level winds early this evening from the Upper Ohio Valley to northern Appalachians. A small temporal window may exist for a supercell-related brief tornado risk near the Ohio/Pennsylvania/West Virginia border area as low-level hodographs enlarge prior to surface-based instability decreasing with eastern extent in Pennsylvania. ...Northern High Plains including Montana to Nebraska... No changes warranted for the region. A mid-level ridge will remain prominent across much of the northern Great Plains through the period, although some flattening is anticipated towards 12Z/Monday as a vigorous shortwave trough amplifies over the Canadian Rockies. Isolated thunderstorms may develop along the lee trough from north-central Montana to the Nebraska/Colorado border area. Buoyancy will be weak to the northwest but may be compensated by plentiful mid to upper-level speed shear. A couple cells with mid-level updraft rotation may form but will likely struggle to be sustained eastward given pronounced MLCIN east of the trough. Have expanded/combined the MRGL risk areas to account for this scenario. Otherwise, an arc of 700-mb warm theta-e advection should yield isolated to perhaps scattered elevated thunderstorms overnight across eastern Montana and the Dakotas into Nebraska. Strongest speed shear will be across the northern portion of the region, with MUCAPE increasing as richer 850-mb moisture advects north. It is unclear whether uncapped parcels can become rooted beneath 700-mb prior to 12Z. For now, will maintain MRGL risk, mainly for the potential of isolated severe hail. Read more

SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0246 PM CDT Sun Sep 01 2019 Valid 012000Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF CENTRAL AND SOUTHERN ARIZONA... ...SUMMARY... Scattered severe wind gusts are possible across parts of central and southern Arizona during the late afternoon and evening, with other severe storms possible across the northern High Plains and Ohio Valley. Little change was required to the previous outlook except to expand low tornado probabilities southwest to the Ohio River where significant low-level CAPE exists as per modified ILN 18Z sounding. Shear is weak, thus any rotation is expected to remain weak and short lived. ..Jewell.. 09/01/2019 .PREV DISCUSSION... /ISSUED 1131 AM CDT Sun Sep 01 2019/ ...Central/southern Arizona... The mid/upper-level ridge will remain centered over the Four Corners area through tonight, with a belt of moderately strong easterly mid-level winds on its immediate southern periphery as sampled by 12Z observed soundings from Phoenix/Tucson. Orographic lift will be the primary driver of isolated to widely scattered thunderstorms by early afternoon across the higher terrain of western New Mexico into central/eastern Arizona. With a belt of 15-25 kt easterlies across the southern half of Arizona, this convection will spread westward over the lower deserts during the late afternoon and evening. Surface dew points should mix into the upper 50s to mid 60s at peak heating across the Lower Colorado and Gila Valleys, yielding at least moderate buoyancy with MLCAPE above 1000 J/kg. One or two clusters may organize off the terrain with a risk for scattered severe-caliber wind gusts, with at least a couple of these storms likely to reach the Lower Colorado River Valley. ...Ohio Valley... A convectively influenced shortwave trough centered over central Indiana at late morning will continue east-northeastward toward the Upper Ohio Valley and western portions of Pennsylvania/New York. Modest ascent ahead of this feature will continue to influence thunderstorm development across the region, with some increase in coverage/intensity this afternoon as MLCAPE reaches 1000-1500 J/kg. The primary risks from multicell clusters should be isolated strong gusts and marginally severe hail. However, guidance is fairly consistent in strengthening low-level winds early this evening from the Upper Ohio Valley to northern Appalachians. A small temporal window may exist for a supercell-related brief tornado risk near the Ohio/Pennsylvania/West Virginia border area as low-level hodographs enlarge prior to surface-based instability decreasing with eastern extent in Pennsylvania. ...Northern High Plains including Montana to Nebraska... No changes warranted for the region. A mid-level ridge will remain prominent across much of the northern Great Plains through the period, although some flattening is anticipated towards 12Z/Monday as a vigorous shortwave trough amplifies over the Canadian Rockies. Isolated thunderstorms may develop along the lee trough from north-central Montana to the Nebraska/Colorado border area. Buoyancy will be weak to the northwest but may be compensated by plentiful mid to upper-level speed shear. A couple cells with mid-level updraft rotation may form but will likely struggle to be sustained eastward given pronounced MLCIN east of the trough. Have expanded/combined the MRGL risk areas to account for this scenario. Otherwise, an arc of 700-mb warm theta-e advection should yield isolated to perhaps scattered elevated thunderstorms overnight across eastern Montana and the Dakotas into Nebraska. Strongest speed shear will be across the northern portion of the region, with MUCAPE increasing as richer 850-mb moisture advects north. It is unclear whether uncapped parcels can become rooted beneath 700-mb prior to 12Z. For now, will maintain MRGL risk, mainly for the potential of isolated severe hail. Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0218 PM CDT Sun Sep 01 2019 Valid 021200Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EASTERN IDAHO... The forecast remains on track, with only minor changes needed with this forecast update to reflect the latest ensemble/deterministic guidance. See previous discussion below for more information. ..Elliott.. 09/01/2019 .PREV DISCUSSION... /ISSUED 0125 AM CDT Sun Sep 01 2019/ ...Synopsis... A mature embedded impulse will traverse the northern Rockies along the crest of a fortified upper-level ridge on Day 2/Monday. Stronger flow aloft will glance the central/northern Rockies and northern Great Basin areas, inducing a surface mass response which will promote very breezy and dry conditions favorable for wildfire spread. ...Northern Great Basin into the central/northern Rockies... Widespread 15-20 mph sustained west-southwesterly winds, coincident with 10-20% RH, are expected to occur by afternoon across much of Wyoming, westward into Idaho and far southern Montana, and continue past sunset, where an elevated delineation was added. An additional downslope component of surface flow along the lee of the Bitterroot Range will also encourage sustained westerly winds of at least 20-25 mph (perhaps with higher gusts) across parts of the Snake River Plain, atop critically dry fuels, where a critical area was added. At least locally critical conditions may also be observed in terrain favoring locations east of the Snake River Plain into the Great Divide basin. However, the lack of widespread stronger flow across these areas lends too low of confidence to expand the critical area eastward at this time, though conditions will be monitored for a possible upgrade in later outlooks. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0218 PM CDT Sun Sep 01 2019 Valid 021200Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EASTERN IDAHO... The forecast remains on track, with only minor changes needed with this forecast update to reflect the latest ensemble/deterministic guidance. See previous discussion below for more information. ..Elliott.. 09/01/2019 .PREV DISCUSSION... /ISSUED 0125 AM CDT Sun Sep 01 2019/ ...Synopsis... A mature embedded impulse will traverse the northern Rockies along the crest of a fortified upper-level ridge on Day 2/Monday. Stronger flow aloft will glance the central/northern Rockies and northern Great Basin areas, inducing a surface mass response which will promote very breezy and dry conditions favorable for wildfire spread. ...Northern Great Basin into the central/northern Rockies... Widespread 15-20 mph sustained west-southwesterly winds, coincident with 10-20% RH, are expected to occur by afternoon across much of Wyoming, westward into Idaho and far southern Montana, and continue past sunset, where an elevated delineation was added. An additional downslope component of surface flow along the lee of the Bitterroot Range will also encourage sustained westerly winds of at least 20-25 mph (perhaps with higher gusts) across parts of the Snake River Plain, atop critically dry fuels, where a critical area was added. At least locally critical conditions may also be observed in terrain favoring locations east of the Snake River Plain into the Great Divide basin. However, the lack of widespread stronger flow across these areas lends too low of confidence to expand the critical area eastward at this time, though conditions will be monitored for a possible upgrade in later outlooks. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0218 PM CDT Sun Sep 01 2019 Valid 021200Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EASTERN IDAHO... The forecast remains on track, with only minor changes needed with this forecast update to reflect the latest ensemble/deterministic guidance. See previous discussion below for more information. ..Elliott.. 09/01/2019 .PREV DISCUSSION... /ISSUED 0125 AM CDT Sun Sep 01 2019/ ...Synopsis... A mature embedded impulse will traverse the northern Rockies along the crest of a fortified upper-level ridge on Day 2/Monday. Stronger flow aloft will glance the central/northern Rockies and northern Great Basin areas, inducing a surface mass response which will promote very breezy and dry conditions favorable for wildfire spread. ...Northern Great Basin into the central/northern Rockies... Widespread 15-20 mph sustained west-southwesterly winds, coincident with 10-20% RH, are expected to occur by afternoon across much of Wyoming, westward into Idaho and far southern Montana, and continue past sunset, where an elevated delineation was added. An additional downslope component of surface flow along the lee of the Bitterroot Range will also encourage sustained westerly winds of at least 20-25 mph (perhaps with higher gusts) across parts of the Snake River Plain, atop critically dry fuels, where a critical area was added. At least locally critical conditions may also be observed in terrain favoring locations east of the Snake River Plain into the Great Divide basin. However, the lack of widespread stronger flow across these areas lends too low of confidence to expand the critical area eastward at this time, though conditions will be monitored for a possible upgrade in later outlooks. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0218 PM CDT Sun Sep 01 2019 Valid 021200Z - 031200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF EASTERN IDAHO... The forecast remains on track, with only minor changes needed with this forecast update to reflect the latest ensemble/deterministic guidance. See previous discussion below for more information. ..Elliott.. 09/01/2019 .PREV DISCUSSION... /ISSUED 0125 AM CDT Sun Sep 01 2019/ ...Synopsis... A mature embedded impulse will traverse the northern Rockies along the crest of a fortified upper-level ridge on Day 2/Monday. Stronger flow aloft will glance the central/northern Rockies and northern Great Basin areas, inducing a surface mass response which will promote very breezy and dry conditions favorable for wildfire spread. ...Northern Great Basin into the central/northern Rockies... Widespread 15-20 mph sustained west-southwesterly winds, coincident with 10-20% RH, are expected to occur by afternoon across much of Wyoming, westward into Idaho and far southern Montana, and continue past sunset, where an elevated delineation was added. An additional downslope component of surface flow along the lee of the Bitterroot Range will also encourage sustained westerly winds of at least 20-25 mph (perhaps with higher gusts) across parts of the Snake River Plain, atop critically dry fuels, where a critical area was added. At least locally critical conditions may also be observed in terrain favoring locations east of the Snake River Plain into the Great Divide basin. However, the lack of widespread stronger flow across these areas lends too low of confidence to expand the critical area eastward at this time, though conditions will be monitored for a possible upgrade in later outlooks. ...Please see www.spc.noaa.gov/fire for graphic product... Read more

MD 1905 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF SOUTHEASTERN INDIANA...NORTHERN KENTUCKY...OHIO
Mesoscale Discussion 1905 NWS Storm Prediction Center Norman OK 0203 PM CDT Sun Sep 01 2019 Areas affected...Parts of southeastern Indiana...northern Kentucky...Ohio Concerning...Severe potential...Watch unlikely Valid 011903Z - 012100Z Probability of Watch Issuance...5 percent SUMMARY...Strong thunderstorms may continue to develop and overspread the region through 6-7 PM EDT, posing at least some risk for severe hail and potentially damaging wind gusts. In general, this risk appears sufficiently marginal in nature that a severe weather watch will not be needed. However, trends will continue to be monitored. DISCUSSION...Weak lower/mid tropospheric (generally within the 850-500 mb layer) troughing is gradually progressing eastward through the lower Ohio Valley. Within the larger-scale cyclonic flow, a convectively generated or enhanced cyclonic vorticity center is now northeast of Indianapolis, and appears likely to continue northeastward across northwest Ohio, into southwestern portions of the Lake Erie by 22-23Z. This is accompanied by a belt of enhanced westerly flow (30-50 kt) to its immediate south, which may be contributing to modest deep layer shear as far south as the Ohio River, where mixed-layer CAPE appears to be increasing to 1000-2000 J/kg in response to daytime heating. Much of the lower Ohio Valley remains under the influence of larger-scale surface ridging, extending to the west of a high center near the New England coast. However, some weakening has been occurring in response to the upper impulse, and there appears a zone of enhanced surface confluence to the south of the MCV, across southern Indiana into southwest Ohio. This has become a focus for developing thunderstorm activity, which probably will be sustained, with further intensification and upscale growth possible during the next few hours. Some of this activity may pose a risk for marginally severe hail, at least initially, with perhaps an increase in potential for strong surface gusts approaching or briefly exceeding severe limits a bit more prominent thereafter, into early evening, across parts of central into eastern Ohio. ..Kerr/Guyer.. 09/01/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PBZ...RLX...CLE...ILN...LMK...IND... LAT...LON 40958254 41018188 40898110 40458108 39948157 38508392 38458629 39898491 40208441 40598334 40958254 Read more

No Mesoscale Discussions are in effect as of Sun Sep 1 17:55:03 UTC 2019.

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 PM CDT Sun Sep 01 2019 Valid 021200Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE DAKOTAS INTO WESTERN WISCONSIN... ...SUMMARY... Severe thunderstorms are expected over parts of the northern Plains and upper Mississippi Valley Monday through early Tuesday morning. Damaging winds and hail are likely. Isolated severe storms are possible across parts of southern New England and extending southward into northern Virginia. ...Synopsis... The upper ridge will flatten over the northern Rockies/High Plains as a powerful shortwave trough develops southeastward out of Canada. This wave will be located over MT during the day, and will accelerate southeastward across the Dakotas and MN Monday night. At the surface, low pressure will deepen as it moves from ND eastward toward Lake Superior, with a cold front moving from the western Dakotas Monday afternoon to the MS River by early Tuesday morning. Extending east of the low will be a warm front, which will lift north across ND and MN late in the day and overnight. Cooling aloft and southerly low-level winds will result in destabilization over the region, with large-scale lift resulting in a severe hail and wind threat. To the east, a shortwave trough will move across the Northeast, with moderate westerlies and cooling aloft. Southerly winds ahead of a cold front will result in destabilization and may support isolated severe storms, from northern VA into southern New England. ...Dakotas...Minnesota...Wisconsin... Early day storms are possible in the warm advection regime from northeastern MT into ND, with elevated storms producing hail. Lift aided by a strengthening low-level jet will persist throughout the day, with increasing elevated storm coverage from ND into northern MN. Although the boundary layer will be cool there, damaging winds may occur should the storms organize into a substantial MCS with hail-laden outflow. Otherwise, large, perhaps very large, hail is possible. Farther south, the stronger low-level lapse rates will develop over the far western Dakotas and Nebraska. There are questions regarding capping and potential storm coverage from central SD into southern MN and IA, however, there is a high conditional threat of severe hail and wind should storms materialize. The ECMWF model shows substantially more storms than the NAM, for example. Given these uncertainties, will maintain a broad 15% with potential significant hail or wind, but a corridor of higher probabilities may be added as predictability increases, most likely from ND into parts of MN. ...Northern VA into southern New England... Rain and storms are expected to be ongoing Monday morning over parts of NY and PA near a deepening surface trough and aided by low-level warm advection. This will play a role in where the greatest destabilization occurs should areas of outflow exist. In general, destabilization will occur ahead of the morning activity, with increasing storm trends into the afternoon toward New York City and across southern New England. Veering winds with height may even support a supercell or two, though low-level shear values will not be particularly strong. A brief/weak tornado cannot be ruled out, in addition to marginal hail. Farther south into VA and MD, strong heating ahead of the wind shift beneath good mid to upper flow will likely support isolated cells capable of hail. ...Florida East Coast... The center of Hurricane Dorian is currently forecast to remain offshore the east coast of Florida on Monday, including most of the outer convective bands. However, increasing low-level convergence within a moist air mass may allow for at least isolated, southwestward-moving cells late Monday into Tuesday morning generally east of Lake Okeechobee, with a gradual increase in low-level shear. The tornado threat appears too low at this time to introduce typical 5% tornado probabilities, but may increase with time depending on the track. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% SIG - Slight ..Jewell.. 09/01/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 PM CDT Sun Sep 01 2019 Valid 021200Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE DAKOTAS INTO WESTERN WISCONSIN... ...SUMMARY... Severe thunderstorms are expected over parts of the northern Plains and upper Mississippi Valley Monday through early Tuesday morning. Damaging winds and hail are likely. Isolated severe storms are possible across parts of southern New England and extending southward into northern Virginia. ...Synopsis... The upper ridge will flatten over the northern Rockies/High Plains as a powerful shortwave trough develops southeastward out of Canada. This wave will be located over MT during the day, and will accelerate southeastward across the Dakotas and MN Monday night. At the surface, low pressure will deepen as it moves from ND eastward toward Lake Superior, with a cold front moving from the western Dakotas Monday afternoon to the MS River by early Tuesday morning. Extending east of the low will be a warm front, which will lift north across ND and MN late in the day and overnight. Cooling aloft and southerly low-level winds will result in destabilization over the region, with large-scale lift resulting in a severe hail and wind threat. To the east, a shortwave trough will move across the Northeast, with moderate westerlies and cooling aloft. Southerly winds ahead of a cold front will result in destabilization and may support isolated severe storms, from northern VA into southern New England. ...Dakotas...Minnesota...Wisconsin... Early day storms are possible in the warm advection regime from northeastern MT into ND, with elevated storms producing hail. Lift aided by a strengthening low-level jet will persist throughout the day, with increasing elevated storm coverage from ND into northern MN. Although the boundary layer will be cool there, damaging winds may occur should the storms organize into a substantial MCS with hail-laden outflow. Otherwise, large, perhaps very large, hail is possible. Farther south, the stronger low-level lapse rates will develop over the far western Dakotas and Nebraska. There are questions regarding capping and potential storm coverage from central SD into southern MN and IA, however, there is a high conditional threat of severe hail and wind should storms materialize. The ECMWF model shows substantially more storms than the NAM, for example. Given these uncertainties, will maintain a broad 15% with potential significant hail or wind, but a corridor of higher probabilities may be added as predictability increases, most likely from ND into parts of MN. ...Northern VA into southern New England... Rain and storms are expected to be ongoing Monday morning over parts of NY and PA near a deepening surface trough and aided by low-level warm advection. This will play a role in where the greatest destabilization occurs should areas of outflow exist. In general, destabilization will occur ahead of the morning activity, with increasing storm trends into the afternoon toward New York City and across southern New England. Veering winds with height may even support a supercell or two, though low-level shear values will not be particularly strong. A brief/weak tornado cannot be ruled out, in addition to marginal hail. Farther south into VA and MD, strong heating ahead of the wind shift beneath good mid to upper flow will likely support isolated cells capable of hail. ...Florida East Coast... The center of Hurricane Dorian is currently forecast to remain offshore the east coast of Florida on Monday, including most of the outer convective bands. However, increasing low-level convergence within a moist air mass may allow for at least isolated, southwestward-moving cells late Monday into Tuesday morning generally east of Lake Okeechobee, with a gradual increase in low-level shear. The tornado threat appears too low at this time to introduce typical 5% tornado probabilities, but may increase with time depending on the track. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% SIG - Slight ..Jewell.. 09/01/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 PM CDT Sun Sep 01 2019 Valid 021200Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE DAKOTAS INTO WESTERN WISCONSIN... ...SUMMARY... Severe thunderstorms are expected over parts of the northern Plains and upper Mississippi Valley Monday through early Tuesday morning. Damaging winds and hail are likely. Isolated severe storms are possible across parts of southern New England and extending southward into northern Virginia. ...Synopsis... The upper ridge will flatten over the northern Rockies/High Plains as a powerful shortwave trough develops southeastward out of Canada. This wave will be located over MT during the day, and will accelerate southeastward across the Dakotas and MN Monday night. At the surface, low pressure will deepen as it moves from ND eastward toward Lake Superior, with a cold front moving from the western Dakotas Monday afternoon to the MS River by early Tuesday morning. Extending east of the low will be a warm front, which will lift north across ND and MN late in the day and overnight. Cooling aloft and southerly low-level winds will result in destabilization over the region, with large-scale lift resulting in a severe hail and wind threat. To the east, a shortwave trough will move across the Northeast, with moderate westerlies and cooling aloft. Southerly winds ahead of a cold front will result in destabilization and may support isolated severe storms, from northern VA into southern New England. ...Dakotas...Minnesota...Wisconsin... Early day storms are possible in the warm advection regime from northeastern MT into ND, with elevated storms producing hail. Lift aided by a strengthening low-level jet will persist throughout the day, with increasing elevated storm coverage from ND into northern MN. Although the boundary layer will be cool there, damaging winds may occur should the storms organize into a substantial MCS with hail-laden outflow. Otherwise, large, perhaps very large, hail is possible. Farther south, the stronger low-level lapse rates will develop over the far western Dakotas and Nebraska. There are questions regarding capping and potential storm coverage from central SD into southern MN and IA, however, there is a high conditional threat of severe hail and wind should storms materialize. The ECMWF model shows substantially more storms than the NAM, for example. Given these uncertainties, will maintain a broad 15% with potential significant hail or wind, but a corridor of higher probabilities may be added as predictability increases, most likely from ND into parts of MN. ...Northern VA into southern New England... Rain and storms are expected to be ongoing Monday morning over parts of NY and PA near a deepening surface trough and aided by low-level warm advection. This will play a role in where the greatest destabilization occurs should areas of outflow exist. In general, destabilization will occur ahead of the morning activity, with increasing storm trends into the afternoon toward New York City and across southern New England. Veering winds with height may even support a supercell or two, though low-level shear values will not be particularly strong. A brief/weak tornado cannot be ruled out, in addition to marginal hail. Farther south into VA and MD, strong heating ahead of the wind shift beneath good mid to upper flow will likely support isolated cells capable of hail. ...Florida East Coast... The center of Hurricane Dorian is currently forecast to remain offshore the east coast of Florida on Monday, including most of the outer convective bands. However, increasing low-level convergence within a moist air mass may allow for at least isolated, southwestward-moving cells late Monday into Tuesday morning generally east of Lake Okeechobee, with a gradual increase in low-level shear. The tornado threat appears too low at this time to introduce typical 5% tornado probabilities, but may increase with time depending on the track. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% SIG - Slight ..Jewell.. 09/01/2019 Read more

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1231 PM CDT Sun Sep 01 2019 Valid 021200Z - 031200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE DAKOTAS INTO WESTERN WISCONSIN... ...SUMMARY... Severe thunderstorms are expected over parts of the northern Plains and upper Mississippi Valley Monday through early Tuesday morning. Damaging winds and hail are likely. Isolated severe storms are possible across parts of southern New England and extending southward into northern Virginia. ...Synopsis... The upper ridge will flatten over the northern Rockies/High Plains as a powerful shortwave trough develops southeastward out of Canada. This wave will be located over MT during the day, and will accelerate southeastward across the Dakotas and MN Monday night. At the surface, low pressure will deepen as it moves from ND eastward toward Lake Superior, with a cold front moving from the western Dakotas Monday afternoon to the MS River by early Tuesday morning. Extending east of the low will be a warm front, which will lift north across ND and MN late in the day and overnight. Cooling aloft and southerly low-level winds will result in destabilization over the region, with large-scale lift resulting in a severe hail and wind threat. To the east, a shortwave trough will move across the Northeast, with moderate westerlies and cooling aloft. Southerly winds ahead of a cold front will result in destabilization and may support isolated severe storms, from northern VA into southern New England. ...Dakotas...Minnesota...Wisconsin... Early day storms are possible in the warm advection regime from northeastern MT into ND, with elevated storms producing hail. Lift aided by a strengthening low-level jet will persist throughout the day, with increasing elevated storm coverage from ND into northern MN. Although the boundary layer will be cool there, damaging winds may occur should the storms organize into a substantial MCS with hail-laden outflow. Otherwise, large, perhaps very large, hail is possible. Farther south, the stronger low-level lapse rates will develop over the far western Dakotas and Nebraska. There are questions regarding capping and potential storm coverage from central SD into southern MN and IA, however, there is a high conditional threat of severe hail and wind should storms materialize. The ECMWF model shows substantially more storms than the NAM, for example. Given these uncertainties, will maintain a broad 15% with potential significant hail or wind, but a corridor of higher probabilities may be added as predictability increases, most likely from ND into parts of MN. ...Northern VA into southern New England... Rain and storms are expected to be ongoing Monday morning over parts of NY and PA near a deepening surface trough and aided by low-level warm advection. This will play a role in where the greatest destabilization occurs should areas of outflow exist. In general, destabilization will occur ahead of the morning activity, with increasing storm trends into the afternoon toward New York City and across southern New England. Veering winds with height may even support a supercell or two, though low-level shear values will not be particularly strong. A brief/weak tornado cannot be ruled out, in addition to marginal hail. Farther south into VA and MD, strong heating ahead of the wind shift beneath good mid to upper flow will likely support isolated cells capable of hail. ...Florida East Coast... The center of Hurricane Dorian is currently forecast to remain offshore the east coast of Florida on Monday, including most of the outer convective bands. However, increasing low-level convergence within a moist air mass may allow for at least isolated, southwestward-moving cells late Monday into Tuesday morning generally east of Lake Okeechobee, with a gradual increase in low-level shear. The tornado threat appears too low at this time to introduce typical 5% tornado probabilities, but may increase with time depending on the track. ...MAXIMUM RISK BY HAZARD... Tornado: 5% - Slight Wind: 15% - Slight Hail: 15% SIG - Slight ..Jewell.. 09/01/2019 Read more