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SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0228 AM CDT Fri Aug 23 2019 Valid 251200Z - 261200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE NORTHERN AND SOUTHERN PLAINS... ...SUMMARY... Isolated severe thunderstorms are possible on Sunday across portions of the northern and southern Plains. ...Synopsis... Medium-range guidance is in good agreement that a strong shortwave trough embedded within the enhanced westerlies moves from the northern Rockies through the northern Plains on Sunday. This results in a deepening of the cyclonic flow across the north-central CONUS. This pattern evolution will also push a cold front eastward/ southeastward through much of northern Plains. Elsewhere, warm and moist conditions will persist across much of southern Plains and Southeast while weakening high pressure across much of the eastern CONUS will allow for some moisture return into the OH Valley. ...Southern Plains... Air mass across the region will be warm, very moist, and strongly buoyant. Strengthening northwesterly flow aloft will also contribute to moderate vertical shear. Overall environment would support severe potential as long as forcing exists for storm initiation. Current guidance suggests a MCS will be moving out of KS early in the period, with a resulting severe threat anticipated downstream. Low (i.e. 5%) severe probabilities will be introduced with this forecast. More model consistency is needed before issuing higher probabilities. ...Northern Plains... Ample low-level moisture (i.e. dewpoints in the mid to upper 60s) will be in place over the region ahead of the approaching cold front. Even so, relatively warm low to mid-level temperatures will likely limit destabilization, particularly across southern portions of the region where less large-scale forcing for ascent (from the approaching shortwave trough) is expected. The environment supports a severe threat where deep updrafts persists but uncertainty regarding coverage currently precludes higher than 5% probability. ..Mosier.. 08/23/2019 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0156 AM CDT Fri Aug 23 2019 Valid 241200Z - 251200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE SNAKE RIVER VALLEY INTO SOUTHERN WYOMING... ...Synopsis... On D2/Saturday, a strong mid-level jet will overspread the Pacific Northwest with the nose of the jet impinging upon the northern Great Basin/central Rockies. Critical fire weather will be most likely for portions of the Snake River Valley and southern Wyoming. In these locations, terrain-enhanced downslope flow will promote 20-25 mph winds with 10-15% afternoon RH. Upper and potentially mid-level clouds will again be a factor in stunting afternoon heating/boundary-layer mixing, which will likely limit the spatial extent of the critical fire weather threat. Surrounding portions of the northern Great Basin and central Rockies will see elevated fire weather conditions, with similar afternoon RH but winds generally in the 15-20 mph range. ..Wendt.. 08/23/2019 ...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 0156 AM CDT Fri Aug 23 2019 Valid 241200Z - 251200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE SNAKE RIVER VALLEY INTO SOUTHERN WYOMING... ...Synopsis... On D2/Saturday, a strong mid-level jet will overspread the Pacific Northwest with the nose of the jet impinging upon the northern Great Basin/central Rockies. Critical fire weather will be most likely for portions of the Snake River Valley and southern Wyoming. In these locations, terrain-enhanced downslope flow will promote 20-25 mph winds with 10-15% afternoon RH. Upper and potentially mid-level clouds will again be a factor in stunting afternoon heating/boundary-layer mixing, which will likely limit the spatial extent of the critical fire weather threat. Surrounding portions of the northern Great Basin and central Rockies will see elevated fire weather conditions, with similar afternoon RH but winds generally in the 15-20 mph range. ..Wendt.. 08/23/2019 ...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 0156 AM CDT Fri Aug 23 2019 Valid 241200Z - 251200Z ...CRITICAL FIRE WEATHER AREA FOR PORTIONS OF THE SNAKE RIVER VALLEY INTO SOUTHERN WYOMING... ...Synopsis... On D2/Saturday, a strong mid-level jet will overspread the Pacific Northwest with the nose of the jet impinging upon the northern Great Basin/central Rockies. Critical fire weather will be most likely for portions of the Snake River Valley and southern Wyoming. In these locations, terrain-enhanced downslope flow will promote 20-25 mph winds with 10-15% afternoon RH. Upper and potentially mid-level clouds will again be a factor in stunting afternoon heating/boundary-layer mixing, which will likely limit the spatial extent of the critical fire weather threat. Surrounding portions of the northern Great Basin and central Rockies will see elevated fire weather conditions, with similar afternoon RH but winds generally in the 15-20 mph range. ..Wendt.. 08/23/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1240 AM CDT Fri Aug 23 2019 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE PLAINS.... ...SUMMARY... Isolated severe storms are possible over parts of the central and northern southern Plains on Saturday. A severe storm or two is also possible across the northern Plains. ...Synopsis... A shortwave trough is expected to move southeastward from the central High Plains across the central Plains and into the Ozark Plateau on Saturday. Interaction between this shortwave and the moist air mass across the central Plains is expected to result in thunderstorm development. Farther northwest, mean cyclonic flow aloft will progress eastward across western Canada and the northwestern/north-central CONUS. Consequently, enhanced mid-level westerly flow will extend from the Pacific Northwest into the central Rockies by the end of the period (12Z Sunday). A shortwave trough will move quickly eastward within this enhanced flow aloft along the US/Canada border. An associated surface low is expected to move eastward across Saskatchewan and Manitoba, with an attendant cold front moving across eastern MT and into the western Dakotas. Expansive surface high centered over eastern Ontario/western Quebec will keep much of the northeast CONUS free of thunderstorms while warm and moist conditions will persist across the Southeast. ...Central/Southern Plains... Thunderstorms will likely be ongoing from central NE southward into the eastern TX Panhandle/western OK early Saturday morning. Strength and coverage of these storms will have an impact on air mass recovery and destabilization later during the afternoon. Additionally, outflow from these storms could provide a boundary for potential convective initiation. These mesoscale features introduce uncertainty into the forecast. Current expectation is for the air mass to destabilize by the late afternoon with isolated storms developing along the lee trough extending from northeast NM into eastern MT. Higher storm coverage is possible during the evening as a strengthening low-level jet promotes additional thunderstorm development across KS. The environment is characterized by favorable low-level moisture, steep mid-level lapse rates, and strengthening northwesterly flow aloft with enough vertical shear and buoyancy to support severe storms. Uncertainty regarding antecedent storms precludes higher probabilities with this outlook, but an upgrade may be needed in a subsequent outlook if mesoscale details become more clear. ...Northern Plains... Elevated storms will likely be ongoing at the beginning of the period. Modest instability and shear support a marginal hail threat. Recent model guidance has trended towards less low-level moisture during the afternoon and evening across the northern Plains. As a result, convective inhibition remains in place across much of the area, limiting surface-based storm initiation. Best location for surface-based initiation currently appears to be across north-central/northeast ND. Isolated storms are also possible late Saturday night/early Sunday morning along the approaching cold front. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Mosier.. 08/23/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1240 AM CDT Fri Aug 23 2019 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE PLAINS.... ...SUMMARY... Isolated severe storms are possible over parts of the central and northern southern Plains on Saturday. A severe storm or two is also possible across the northern Plains. ...Synopsis... A shortwave trough is expected to move southeastward from the central High Plains across the central Plains and into the Ozark Plateau on Saturday. Interaction between this shortwave and the moist air mass across the central Plains is expected to result in thunderstorm development. Farther northwest, mean cyclonic flow aloft will progress eastward across western Canada and the northwestern/north-central CONUS. Consequently, enhanced mid-level westerly flow will extend from the Pacific Northwest into the central Rockies by the end of the period (12Z Sunday). A shortwave trough will move quickly eastward within this enhanced flow aloft along the US/Canada border. An associated surface low is expected to move eastward across Saskatchewan and Manitoba, with an attendant cold front moving across eastern MT and into the western Dakotas. Expansive surface high centered over eastern Ontario/western Quebec will keep much of the northeast CONUS free of thunderstorms while warm and moist conditions will persist across the Southeast. ...Central/Southern Plains... Thunderstorms will likely be ongoing from central NE southward into the eastern TX Panhandle/western OK early Saturday morning. Strength and coverage of these storms will have an impact on air mass recovery and destabilization later during the afternoon. Additionally, outflow from these storms could provide a boundary for potential convective initiation. These mesoscale features introduce uncertainty into the forecast. Current expectation is for the air mass to destabilize by the late afternoon with isolated storms developing along the lee trough extending from northeast NM into eastern MT. Higher storm coverage is possible during the evening as a strengthening low-level jet promotes additional thunderstorm development across KS. The environment is characterized by favorable low-level moisture, steep mid-level lapse rates, and strengthening northwesterly flow aloft with enough vertical shear and buoyancy to support severe storms. Uncertainty regarding antecedent storms precludes higher probabilities with this outlook, but an upgrade may be needed in a subsequent outlook if mesoscale details become more clear. ...Northern Plains... Elevated storms will likely be ongoing at the beginning of the period. Modest instability and shear support a marginal hail threat. Recent model guidance has trended towards less low-level moisture during the afternoon and evening across the northern Plains. As a result, convective inhibition remains in place across much of the area, limiting surface-based storm initiation. Best location for surface-based initiation currently appears to be across north-central/northeast ND. Isolated storms are also possible late Saturday night/early Sunday morning along the approaching cold front. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Mosier.. 08/23/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1240 AM CDT Fri Aug 23 2019 Valid 241200Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE PLAINS.... ...SUMMARY... Isolated severe storms are possible over parts of the central and northern southern Plains on Saturday. A severe storm or two is also possible across the northern Plains. ...Synopsis... A shortwave trough is expected to move southeastward from the central High Plains across the central Plains and into the Ozark Plateau on Saturday. Interaction between this shortwave and the moist air mass across the central Plains is expected to result in thunderstorm development. Farther northwest, mean cyclonic flow aloft will progress eastward across western Canada and the northwestern/north-central CONUS. Consequently, enhanced mid-level westerly flow will extend from the Pacific Northwest into the central Rockies by the end of the period (12Z Sunday). A shortwave trough will move quickly eastward within this enhanced flow aloft along the US/Canada border. An associated surface low is expected to move eastward across Saskatchewan and Manitoba, with an attendant cold front moving across eastern MT and into the western Dakotas. Expansive surface high centered over eastern Ontario/western Quebec will keep much of the northeast CONUS free of thunderstorms while warm and moist conditions will persist across the Southeast. ...Central/Southern Plains... Thunderstorms will likely be ongoing from central NE southward into the eastern TX Panhandle/western OK early Saturday morning. Strength and coverage of these storms will have an impact on air mass recovery and destabilization later during the afternoon. Additionally, outflow from these storms could provide a boundary for potential convective initiation. These mesoscale features introduce uncertainty into the forecast. Current expectation is for the air mass to destabilize by the late afternoon with isolated storms developing along the lee trough extending from northeast NM into eastern MT. Higher storm coverage is possible during the evening as a strengthening low-level jet promotes additional thunderstorm development across KS. The environment is characterized by favorable low-level moisture, steep mid-level lapse rates, and strengthening northwesterly flow aloft with enough vertical shear and buoyancy to support severe storms. Uncertainty regarding antecedent storms precludes higher probabilities with this outlook, but an upgrade may be needed in a subsequent outlook if mesoscale details become more clear. ...Northern Plains... Elevated storms will likely be ongoing at the beginning of the period. Modest instability and shear support a marginal hail threat. Recent model guidance has trended towards less low-level moisture during the afternoon and evening across the northern Plains. As a result, convective inhibition remains in place across much of the area, limiting surface-based storm initiation. Best location for surface-based initiation currently appears to be across north-central/northeast ND. Isolated storms are also possible late Saturday night/early Sunday morning along the approaching cold front. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Mosier.. 08/23/2019 Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Fri Aug 23 2019 Valid 231200Z - 241200Z ...Synopsis... A mid-level trough currently positioned over the southwest Montana vicinity will progress eastward into the central High Plains today. On the back side of this trough, enhanced mid-level flow will be present over parts of southwestern Wyoming into Utah and eastern Nevada. Potential for elevated fire weather conditions will exist from the Great Divide Basin, western Colorado, and portions of the southern Great Basin. In these locations, 15-20 mph surface winds and 5-20% afternoon RH are probable. Two factors introduce some uncertainty to how widespread these elevated conditions will be: 1) a weakening surface pressure gradient throughout the day and 2) potential for mid/upper-level clouds over portions of Utah/Nevada during the afternoon. Current position of dry air aloft on water vapor satellite imagery would indicate that it may only overlap portions of western Colorado during the afternoon, which is also supported by model forecast soundings. Nonetheless, several areas will see at least briefly elevated conditions with potential for locally critical conditions in terrain-favored locations. ..Wendt.. 08/23/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Fri Aug 23 2019 Valid 231200Z - 241200Z ...Synopsis... A mid-level trough currently positioned over the southwest Montana vicinity will progress eastward into the central High Plains today. On the back side of this trough, enhanced mid-level flow will be present over parts of southwestern Wyoming into Utah and eastern Nevada. Potential for elevated fire weather conditions will exist from the Great Divide Basin, western Colorado, and portions of the southern Great Basin. In these locations, 15-20 mph surface winds and 5-20% afternoon RH are probable. Two factors introduce some uncertainty to how widespread these elevated conditions will be: 1) a weakening surface pressure gradient throughout the day and 2) potential for mid/upper-level clouds over portions of Utah/Nevada during the afternoon. Current position of dry air aloft on water vapor satellite imagery would indicate that it may only overlap portions of western Colorado during the afternoon, which is also supported by model forecast soundings. Nonetheless, several areas will see at least briefly elevated conditions with potential for locally critical conditions in terrain-favored locations. ..Wendt.. 08/23/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1259 AM CDT Fri Aug 23 2019 Valid 231200Z - 241200Z ...Synopsis... A mid-level trough currently positioned over the southwest Montana vicinity will progress eastward into the central High Plains today. On the back side of this trough, enhanced mid-level flow will be present over parts of southwestern Wyoming into Utah and eastern Nevada. Potential for elevated fire weather conditions will exist from the Great Divide Basin, western Colorado, and portions of the southern Great Basin. In these locations, 15-20 mph surface winds and 5-20% afternoon RH are probable. Two factors introduce some uncertainty to how widespread these elevated conditions will be: 1) a weakening surface pressure gradient throughout the day and 2) potential for mid/upper-level clouds over portions of Utah/Nevada during the afternoon. Current position of dry air aloft on water vapor satellite imagery would indicate that it may only overlap portions of western Colorado during the afternoon, which is also supported by model forecast soundings. Nonetheless, several areas will see at least briefly elevated conditions with potential for locally critical conditions in terrain-favored locations. ..Wendt.. 08/23/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Fri Aug 23 2019 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN HIGH PLAINS AND ACROSS PARTS OF SOUTHEAST VA INTO NORTHEAST NC... ...SUMMARY... Severe thunderstorms capable of large hail and damaging wind gusts are possible this afternoon and evening, mainly across eastern Wyoming/Colorado into western Nebraska/Kansas. Severe thunderstorms, mainly capable of damaging wind gusts, are also expected across portions of southeast Virginia into northeast North Carolina this afternoon and evening. ...Synopsis... An upper trough over the northeastern states will continue to lift east/northeast today. The associated surface cold front will extend from near the New England coast this morning, arcing southwest into northern VA and the lower OH/middle MS Valley vicinity. The western extent of the front will push southward and become a focus for strong to severe thunderstorm development across portions of southern VA into NC. Meanwhile, the upper shortwave trough over the western U.S. will slowly shift east across the Rockies to the High Plains. A lee trough and moist, upslope flow regime amidst upper level height falls will focus another round of strong to severe thunderstorms across portions of the High Plains. Elsewhere, a very moist and unstable boundary layer will support sporadic downbursts from Oklahoma into portions of the South. Organized severe threat will be limited by weak flow and a lack of upper forcing for ascent as the area remains under the influence of lower-amplitude southern-stream flow. ...High Plains... While the upper shortwave trough migrating across the region is not particularly strong, unseasonably moist conditions will spread north and west on southeasterly low-level flow. Surface dewpoints well into the 60s will envelop much of the Plains and extend as far west as eastern MT/WY/CO. At the same time, a surface trough will extend southward from eastern WY into the OK/TX Panhandles. Strong heating along the trough beneath very steep midlevel lapse rates (7.5-8.5 C/km) will result in MLCAPE from 1500-3500 J/kg. Scattered thunderstorms will develop near the higher terrain in CO/WY during the afternoon as weak ascent increases with the approach of the trough. Deep-layer flow will remain modest, but vertically veering profiles and stronger low level southeasterly flow will result in 25-40 kt effective shear. This will aid in maintaining organized convection with eastward extent over the High Plains into the evening. By 00z, a 25-35 kt southerly low level jet will develop, aiding in upscale growth of storm clusters. Various guidance is consistent in developing one or more bowing segments tracking east/southeast across parts of eastern WY/CO into western NE/KS. Initial convection could pose a large-hail threat as it remains semi-discrete moving off of the higher terrain. However, with time, cells and clusters are expected to organized into one or more bowing segments with an attendant increase in damaging wind potential during the evening hours. The northward extent of severe potential will be limited across eastern MT/western ND as remnant overnight convection and cloud cover limit heating, resulting in capping concerns. Any convection that redevelops overnight tonight likely will be elevated. ...Portions of Southern VA into the Carolinas... A very moist airmass (surface dewpoints in the 70s F) will reside across southeast VA into the Carolinas ahead of the southward-advancing cold front. Deep-layer flow is not particularly strong, similar to the previous few days. However, guidance suggests a shortwave impulse will eject across the central Appalachians during the afternoon as the southern extent of the upper trough pivots across the area. This will result in a band of around 25-30 kt midlevel flow and effective shear will increase modestly. As forcing increases both in relation to this shortwave impulse and the approaching front, strong destabilization will result in scattered thunderstorm development by midday. Somewhat stronger flow compared to previous days in the presence of the cold front should allow for better organized storm clusters and possibly one or more bowing segments tracking eastward across southeast VA into central/eastern NC and possibly parts of SC, though deep layer weakens quickly with southward extent. Steep low-level lapse rates and PW values greater than 2 inches will further support organized damaging-wind potential during the afternoon and evening. While midlevel lapse rates will be modest, some stronger cells could produce hail as well. ..Leitman/Wendt.. 08/23/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Fri Aug 23 2019 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN HIGH PLAINS AND ACROSS PARTS OF SOUTHEAST VA INTO NORTHEAST NC... ...SUMMARY... Severe thunderstorms capable of large hail and damaging wind gusts are possible this afternoon and evening, mainly across eastern Wyoming/Colorado into western Nebraska/Kansas. Severe thunderstorms, mainly capable of damaging wind gusts, are also expected across portions of southeast Virginia into northeast North Carolina this afternoon and evening. ...Synopsis... An upper trough over the northeastern states will continue to lift east/northeast today. The associated surface cold front will extend from near the New England coast this morning, arcing southwest into northern VA and the lower OH/middle MS Valley vicinity. The western extent of the front will push southward and become a focus for strong to severe thunderstorm development across portions of southern VA into NC. Meanwhile, the upper shortwave trough over the western U.S. will slowly shift east across the Rockies to the High Plains. A lee trough and moist, upslope flow regime amidst upper level height falls will focus another round of strong to severe thunderstorms across portions of the High Plains. Elsewhere, a very moist and unstable boundary layer will support sporadic downbursts from Oklahoma into portions of the South. Organized severe threat will be limited by weak flow and a lack of upper forcing for ascent as the area remains under the influence of lower-amplitude southern-stream flow. ...High Plains... While the upper shortwave trough migrating across the region is not particularly strong, unseasonably moist conditions will spread north and west on southeasterly low-level flow. Surface dewpoints well into the 60s will envelop much of the Plains and extend as far west as eastern MT/WY/CO. At the same time, a surface trough will extend southward from eastern WY into the OK/TX Panhandles. Strong heating along the trough beneath very steep midlevel lapse rates (7.5-8.5 C/km) will result in MLCAPE from 1500-3500 J/kg. Scattered thunderstorms will develop near the higher terrain in CO/WY during the afternoon as weak ascent increases with the approach of the trough. Deep-layer flow will remain modest, but vertically veering profiles and stronger low level southeasterly flow will result in 25-40 kt effective shear. This will aid in maintaining organized convection with eastward extent over the High Plains into the evening. By 00z, a 25-35 kt southerly low level jet will develop, aiding in upscale growth of storm clusters. Various guidance is consistent in developing one or more bowing segments tracking east/southeast across parts of eastern WY/CO into western NE/KS. Initial convection could pose a large-hail threat as it remains semi-discrete moving off of the higher terrain. However, with time, cells and clusters are expected to organized into one or more bowing segments with an attendant increase in damaging wind potential during the evening hours. The northward extent of severe potential will be limited across eastern MT/western ND as remnant overnight convection and cloud cover limit heating, resulting in capping concerns. Any convection that redevelops overnight tonight likely will be elevated. ...Portions of Southern VA into the Carolinas... A very moist airmass (surface dewpoints in the 70s F) will reside across southeast VA into the Carolinas ahead of the southward-advancing cold front. Deep-layer flow is not particularly strong, similar to the previous few days. However, guidance suggests a shortwave impulse will eject across the central Appalachians during the afternoon as the southern extent of the upper trough pivots across the area. This will result in a band of around 25-30 kt midlevel flow and effective shear will increase modestly. As forcing increases both in relation to this shortwave impulse and the approaching front, strong destabilization will result in scattered thunderstorm development by midday. Somewhat stronger flow compared to previous days in the presence of the cold front should allow for better organized storm clusters and possibly one or more bowing segments tracking eastward across southeast VA into central/eastern NC and possibly parts of SC, though deep layer weakens quickly with southward extent. Steep low-level lapse rates and PW values greater than 2 inches will further support organized damaging-wind potential during the afternoon and evening. While midlevel lapse rates will be modest, some stronger cells could produce hail as well. ..Leitman/Wendt.. 08/23/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1255 AM CDT Fri Aug 23 2019 Valid 231200Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL AND SOUTHERN HIGH PLAINS AND ACROSS PARTS OF SOUTHEAST VA INTO NORTHEAST NC... ...SUMMARY... Severe thunderstorms capable of large hail and damaging wind gusts are possible this afternoon and evening, mainly across eastern Wyoming/Colorado into western Nebraska/Kansas. Severe thunderstorms, mainly capable of damaging wind gusts, are also expected across portions of southeast Virginia into northeast North Carolina this afternoon and evening. ...Synopsis... An upper trough over the northeastern states will continue to lift east/northeast today. The associated surface cold front will extend from near the New England coast this morning, arcing southwest into northern VA and the lower OH/middle MS Valley vicinity. The western extent of the front will push southward and become a focus for strong to severe thunderstorm development across portions of southern VA into NC. Meanwhile, the upper shortwave trough over the western U.S. will slowly shift east across the Rockies to the High Plains. A lee trough and moist, upslope flow regime amidst upper level height falls will focus another round of strong to severe thunderstorms across portions of the High Plains. Elsewhere, a very moist and unstable boundary layer will support sporadic downbursts from Oklahoma into portions of the South. Organized severe threat will be limited by weak flow and a lack of upper forcing for ascent as the area remains under the influence of lower-amplitude southern-stream flow. ...High Plains... While the upper shortwave trough migrating across the region is not particularly strong, unseasonably moist conditions will spread north and west on southeasterly low-level flow. Surface dewpoints well into the 60s will envelop much of the Plains and extend as far west as eastern MT/WY/CO. At the same time, a surface trough will extend southward from eastern WY into the OK/TX Panhandles. Strong heating along the trough beneath very steep midlevel lapse rates (7.5-8.5 C/km) will result in MLCAPE from 1500-3500 J/kg. Scattered thunderstorms will develop near the higher terrain in CO/WY during the afternoon as weak ascent increases with the approach of the trough. Deep-layer flow will remain modest, but vertically veering profiles and stronger low level southeasterly flow will result in 25-40 kt effective shear. This will aid in maintaining organized convection with eastward extent over the High Plains into the evening. By 00z, a 25-35 kt southerly low level jet will develop, aiding in upscale growth of storm clusters. Various guidance is consistent in developing one or more bowing segments tracking east/southeast across parts of eastern WY/CO into western NE/KS. Initial convection could pose a large-hail threat as it remains semi-discrete moving off of the higher terrain. However, with time, cells and clusters are expected to organized into one or more bowing segments with an attendant increase in damaging wind potential during the evening hours. The northward extent of severe potential will be limited across eastern MT/western ND as remnant overnight convection and cloud cover limit heating, resulting in capping concerns. Any convection that redevelops overnight tonight likely will be elevated. ...Portions of Southern VA into the Carolinas... A very moist airmass (surface dewpoints in the 70s F) will reside across southeast VA into the Carolinas ahead of the southward-advancing cold front. Deep-layer flow is not particularly strong, similar to the previous few days. However, guidance suggests a shortwave impulse will eject across the central Appalachians during the afternoon as the southern extent of the upper trough pivots across the area. This will result in a band of around 25-30 kt midlevel flow and effective shear will increase modestly. As forcing increases both in relation to this shortwave impulse and the approaching front, strong destabilization will result in scattered thunderstorm development by midday. Somewhat stronger flow compared to previous days in the presence of the cold front should allow for better organized storm clusters and possibly one or more bowing segments tracking eastward across southeast VA into central/eastern NC and possibly parts of SC, though deep layer weakens quickly with southward extent. Steep low-level lapse rates and PW values greater than 2 inches will further support organized damaging-wind potential during the afternoon and evening. While midlevel lapse rates will be modest, some stronger cells could produce hail as well. ..Leitman/Wendt.. 08/23/2019 Read more

000
ABPZ20 KNHC 230503
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 PM PDT Thu Aug 22 2019

For the eastern North Pacific...east of 140 degrees west longitude:

The National Hurricane Center is issuing advisories on Tropical
Storm Ivo, located several hundred miles southwest of the southern
tip of the Baja California peninsula.

A surface trough located about 1100 miles east-southeast of the
Big Island of Hawaii continues to produce disorganized cloudiness
and showers. Although this disturbance is not showing any signs of
development at this time, environmental conditions could become
a little more conducive for some development in the central Pacific
well to the east of the Hawaiian Islands in a few days. The system
is forecast to move slowly northwestward.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...low...30 percent.

$$
Forecaster Avila

A full burn ban remained in effect for Haines, despite a little bit of rain. All open fires were prohibited, including burn barrels and waste piles. The increased fire danger, due to dry conditions, prompted the federal Division of Forestry to send additional equipment and personnel, including a special fire engine designed to fight brush fires and several helicopter-trained federal wildland firefighters. KHNS (Haines, Alaska), Aug. 23, 2019 A burn ban remained in effect for Haines as drought continued. Arkansas Democrat-Gazette & Arkansas Online (Alaska), Aug. 18, 2019

5-Day Uncertainty Track last updated Fri, 23 Aug 2019 02:33:02 GMT


Wind Speed Probabilities last updated Fri, 23 Aug 2019 03:31:10 GMT

Issued at 900 PM MDT Thu Aug 22 2019 885 WTPZ45 KNHC 230232 TCDEP5 Tropical Storm Ivo Discussion Number 7 NWS National Hurricane Center Miami FL EP102019 900 PM MDT Thu Aug 22 2019 Visible satellite pictures show that the center of Ivo has become exposed to the northeast of the deep convection due to moderate to strong northeasterly shear. Although the latest Dvorak T-numbers have decreased slightly, the initial intensity is being held at 55 kt which is in agreement with earlier ASCAT data and recent UW/CIMSS SATCON estimates. Overnight scatterometer data should provide a better assessment of Ivo's intensity. Guidance suggests that the shear is likely to remain moderate to strong during the next 12-18 hours while Ivo traverses warm waters. The shear could relax Friday night, but by that time the cyclone is forecast to move over decreasing SSTs and into a less favorable thermodynamic environment. As a result, little overall change in strength is anticipated during the next day or so. After that time, Ivo should weaken as it moves over SSTs below 26C and into a stable air mass. The cyclone is forecast to become a remnant low within 72 hours, and dissipate by day 5. Ivo has turned sharply today, with the initial motion now north-northwestward or 335/8 kt. The storm is forecast to move northwestward to north-northwestward around the western side of a mid-level ridge. The latest track envelope has shifted eastward, partially due to the sharper turn and the more eastward initial position. This has resulted in a slightly eastward shift in the official forecast, but it remains close to the various consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 23/0300Z 16.9N 114.1W 55 KT 65 MPH 12H 23/1200Z 18.0N 115.0W 55 KT 65 MPH 24H 24/0000Z 19.5N 115.9W 55 KT 65 MPH 36H 24/1200Z 21.2N 116.8W 50 KT 60 MPH 48H 25/0000Z 23.0N 117.6W 40 KT 45 MPH 72H 26/0000Z 26.6N 119.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 27/0000Z 28.5N 120.2W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 28/0000Z...DISSIPATED $$ Forecaster Brown

Issued at 0300 UTC FRI AUG 23 2019 000 FOPZ15 KNHC 230232 PWSEP5 TROPICAL STORM IVO WIND SPEED PROBABILITIES NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL EP102019 0300 UTC FRI AUG 23 2019 AT 0300Z THE CENTER OF TROPICAL STORM IVO WAS LOCATED NEAR LATITUDE 16.9 NORTH...LONGITUDE 114.1 WEST WITH MAXIMUM SUSTAINED WINDS NEAR 55 KTS...65 MPH...100 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 00Z FRI 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 00Z FRI 12Z FRI 00Z SAT 12Z SAT 00Z SUN 00Z MON 00Z TUE PERIODS TO TO TO TO TO TO TO 12Z FRI 00Z SAT 12Z SAT 00Z SUN 00Z MON 00Z TUE 00Z WED FORECAST HOUR (12) (24) (36) (48) (72) (96) (120) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - LOCATION KT IS GUADALUPE 34 X X( X) X( X) X( X) 3( 3) 2( 5) X( 5) ISLA SOCORRO 34 2 2( 4) X( 4) X( 4) X( 4) X( 4) X( 4) ISLA CLARION 34 74 15(89) X(89) X(89) X(89) X(89) X(89) ISLA CLARION 50 22 22(44) 1(45) X(45) X(45) X(45) X(45) ISLA CLARION 64 3 3( 6) X( 6) X( 6) X( 6) X( 6) X( 6) 15N 115W 34 4 2( 6) X( 6) X( 6) X( 6) X( 6) X( 6) 20N 115W 34 6 44(50) 8(58) X(58) X(58) X(58) X(58) 20N 115W 50 X 10(10) 4(14) X(14) X(14) X(14) X(14) 20N 115W 64 X 2( 2) X( 2) X( 2) X( 2) X( 2) X( 2) 25N 115W 34 X X( X) 2( 2) 2( 4) 2( 6) X( 6) X( 6) 20N 120W 34 1 3( 4) 1( 5) 1( 6) X( 6) X( 6) X( 6) 25N 120W 34 X X( X) 1( 1) 2( 3) 14(17) 2(19) X(19) 25N 120W 50 X X( X) X( X) X( X) 3( 3) X( 3) X( 3) 30N 120W 34 X X( X) X( X) X( X) 1( 1) 2( 3) X( 3) $$ FORECASTER BROWN

...IVO TURNS NORTH-NORTHWESTWARD... As of 9:00 PM MDT Thu Aug 22 the center of Ivo was located near 16.9, -114.1 with movement NNW at 9 mph. The minimum central pressure was 996 mb with maximum sustained winds of about 65 mph.

SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0744 PM CDT Thu Aug 22 2019 Valid 230100Z - 231200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE HIGH PLAINS...OK/AR...AND PARTS OF THE MID-ATLANTIC... ...SUMMARY... Isolated damaging winds and hail remain possible across parts of the northern High Plains through tonight. Additional strong gusts are possible across parts of northeast Colorado and southwest Nebraska, as well as parts of Oklahoma and Arkansas and the Mid-Atlantic over the next couple of hours. ...01z Update... Changes to the Day 1 outlook have been made to reflect current strong to occasionally severe storms/clusters ongoing this evening. Some areas have been dropped from the Marginal risk, with a continued Marginal risk being highlighted across parts of the northern Rockies and adjacent High Plains of northeast WY into eastern MT and far western ND. Widely scattered storms have begun developing in the vicinity of a surface low and cold front from Johnson and Sheridan Counties in WY northward into Rosebud County MT. These storms will pose a threat of strong wind gusts and possibly some hail through the evening. Discrete cells are still expected to quickly transition into eastward progressing clusters or line segments, with a continued risk for sporadically severe wind gusts through the overnight hours. Elsewhere, a short-term threat will exist with ongoing storms across several areas of the country, before weakening over the next 1-3 hours. This includes: A cluster of storms across northeast CO into southwest NE continue to pose a threat for strong wind gusts in the short term. This cluster is expected to gradually weaken with time with the loss of daytime heating and a stabilizing boundary layer. Another cluster of storms has developed across central OK along an outflow boundary, with additional sub-severe clusters further east into northern AR. These storms could produce marginally severe wind gusts and hail over the next couple of hours, with the Oklahoma segment appearing somewhat more organized. However, the lack of a stronger developing low level jet should result in gradual weakening over the next couple of hours as the boundary layer stabilizes and remaining convection becomes more elevated. Across the Mid-Atlantic, clusters of storms were ongoing across eastern NC northward to the Washington D.C./Chesapeake Bay area, as well as a cluster moving over NYC and Long Island. These storms will continue to pose a threat for strong gusts, especially from the greater Washington D.C. area northward to Long Island. These clusters are maintaining organization/intensity aided by 25-35 kt effective shear. As storms move offshore, the threat will end. ..Leitman.. 08/23/2019 Read more