Aggregator

...KIKO NOW WEAKENING AS IT CONTINUES WESTWARD... As of 2:00 AM PDT Mon Sep 16 the center of Kiko was located near 17.2, -123.1 with movement W at 6 mph. The minimum central pressure was 963 mb with maximum sustained winds of about 115 mph.

Issued at 0900 UTC MON SEP 16 2019 000 WTPZ23 KNHC 160838 TCMEP3 HURRICANE KIKO FORECAST/ADVISORY NUMBER 16 NWS NATIONAL HURRICANE CENTER MIAMI FL EP132019 0900 UTC MON SEP 16 2019 THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT. HURRICANE CENTER LOCATED NEAR 17.2N 123.1W AT 16/0900Z POSITION ACCURATE WITHIN 30 NM PRESENT MOVEMENT TOWARD THE WEST OR 270 DEGREES AT 5 KT ESTIMATED MINIMUM CENTRAL PRESSURE 963 MB MAX SUSTAINED WINDS 100 KT WITH GUSTS TO 120 KT. 64 KT....... 15NE 15SE 15SW 15NW. 50 KT....... 30NE 30SE 30SW 30NW. 34 KT....... 50NE 50SE 50SW 50NW. 12 FT SEAS..120NE 90SE 90SW 120NW. 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 17.2N 123.1W AT 16/0900Z AT 16/0600Z CENTER WAS LOCATED NEAR 17.2N 122.9W FORECAST VALID 16/1800Z 17.2N 123.8W MAX WIND 90 KT...GUSTS 110 KT. 64 KT... 15NE 15SE 15SW 15NW. 50 KT... 30NE 30SE 30SW 30NW. 34 KT... 50NE 50SE 50SW 50NW. FORECAST VALID 17/0600Z 17.2N 124.7W MAX WIND 80 KT...GUSTS 100 KT. 64 KT... 15NE 15SE 15SW 15NW. 50 KT... 30NE 30SE 30SW 30NW. 34 KT... 50NE 50SE 50SW 50NW. FORECAST VALID 17/1800Z 17.0N 125.5W MAX WIND 75 KT...GUSTS 90 KT. 64 KT... 15NE 15SE 15SW 15NW. 50 KT... 30NE 30SE 30SW 30NW. 34 KT... 50NE 50SE 50SW 50NW. FORECAST VALID 18/0600Z 16.8N 126.4W MAX WIND 70 KT...GUSTS 85 KT. 64 KT... 15NE 15SE 15SW 15NW. 50 KT... 30NE 30SE 30SW 30NW. 34 KT... 50NE 50SE 50SW 50NW. FORECAST VALID 19/0600Z 17.0N 128.3W MAX WIND 70 KT...GUSTS 85 KT. 50 KT... 30NE 30SE 30SW 30NW. 34 KT... 50NE 50SE 50SW 50NW. 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 20/0600Z 17.2N 130.0W MAX WIND 65 KT...GUSTS 80 KT. OUTLOOK VALID 21/0600Z 17.3N 131.5W MAX WIND 55 KT...GUSTS 65 KT. REQUEST FOR 3 HOURLY SHIP REPORTS WITHIN 300 MILES OF 17.2N 123.1W NEXT ADVISORY AT 16/1500Z $$ FORECASTER LATTO

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0213 AM CDT Mon Sep 16 2019 Valid 181200Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few strong thunderstorms are possible across parts of the Upper Midwest Wednesday afternoon and evening, but the risk for severe weather currently appears negligible. ...Discussion... Within the westerlies, models indicate that amplified mid-level troughing, near the northern Pacific coast at the start of the period, will gradually dig inland through the northern and central Intermountain West and Sierra Nevada Mountains vicinity Wednesday through Wednesday night. As this occurs, large-scale downstream ridging is forecast to build east-northeast of the northern Rockies, toward northwest Ontario and the Upper Great Lakes region. At the same time, ridging appears likely to remain strong along an axis from the lower Ohio Valley through the lower Great Lakes region, with the increasingly deformed remnants of a vigorous short wave impulse migrating around its western/northern periphery, across northwestern Ontario by late Wednesday night. At 12Z Wednesday, it appears that the vigorous impulse will probably be approaching the North Dakota/Manitoba border area, with stronger associated forcing for ascent and deep-layer wind fields generally shifting north of the international border early in the day. Models indicate that this may contribute to substantive deepening of a surface cyclone migrating across Manitoba into Hudson Bay, but the trailing cold front may stall and weaken across portions of the Upper Midwest. Seasonably moist boundary layer air may linger along this front and contribute to moderately large CAPE (2000+ J/kg) with daytime heating, along a corridor through central Iowa, southeastern Minnesota and western Wisconsin by late Wednesday afternoon. While this could support the development of scattered vigorous thunderstorm activity, questions remain concerning mid-level inhibition and weak to negligible large-scale forcing for ascent. Given generally weak and/or weakening vertical shear expected across this region, the potential for severe thunderstorms still appears negligible at the present time. Elsewhere, in lower latitudes, some model guidance indicates strengthening of southerly low-level wind fields to the east of an inland migrating tropical cyclone, across the upper Texas coastal plain during this period. This could be accompanied by enlarging hodographs sufficient to support a risk for tornadoes, in the presence of tropical boundary layer moisture. At this point, however, this potential appears too low to introduce severe probabilities. ..Kerr.. 09/16/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0213 AM CDT Mon Sep 16 2019 Valid 181200Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few strong thunderstorms are possible across parts of the Upper Midwest Wednesday afternoon and evening, but the risk for severe weather currently appears negligible. ...Discussion... Within the westerlies, models indicate that amplified mid-level troughing, near the northern Pacific coast at the start of the period, will gradually dig inland through the northern and central Intermountain West and Sierra Nevada Mountains vicinity Wednesday through Wednesday night. As this occurs, large-scale downstream ridging is forecast to build east-northeast of the northern Rockies, toward northwest Ontario and the Upper Great Lakes region. At the same time, ridging appears likely to remain strong along an axis from the lower Ohio Valley through the lower Great Lakes region, with the increasingly deformed remnants of a vigorous short wave impulse migrating around its western/northern periphery, across northwestern Ontario by late Wednesday night. At 12Z Wednesday, it appears that the vigorous impulse will probably be approaching the North Dakota/Manitoba border area, with stronger associated forcing for ascent and deep-layer wind fields generally shifting north of the international border early in the day. Models indicate that this may contribute to substantive deepening of a surface cyclone migrating across Manitoba into Hudson Bay, but the trailing cold front may stall and weaken across portions of the Upper Midwest. Seasonably moist boundary layer air may linger along this front and contribute to moderately large CAPE (2000+ J/kg) with daytime heating, along a corridor through central Iowa, southeastern Minnesota and western Wisconsin by late Wednesday afternoon. While this could support the development of scattered vigorous thunderstorm activity, questions remain concerning mid-level inhibition and weak to negligible large-scale forcing for ascent. Given generally weak and/or weakening vertical shear expected across this region, the potential for severe thunderstorms still appears negligible at the present time. Elsewhere, in lower latitudes, some model guidance indicates strengthening of southerly low-level wind fields to the east of an inland migrating tropical cyclone, across the upper Texas coastal plain during this period. This could be accompanied by enlarging hodographs sufficient to support a risk for tornadoes, in the presence of tropical boundary layer moisture. At this point, however, this potential appears too low to introduce severe probabilities. ..Kerr.. 09/16/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0213 AM CDT Mon Sep 16 2019 Valid 181200Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few strong thunderstorms are possible across parts of the Upper Midwest Wednesday afternoon and evening, but the risk for severe weather currently appears negligible. ...Discussion... Within the westerlies, models indicate that amplified mid-level troughing, near the northern Pacific coast at the start of the period, will gradually dig inland through the northern and central Intermountain West and Sierra Nevada Mountains vicinity Wednesday through Wednesday night. As this occurs, large-scale downstream ridging is forecast to build east-northeast of the northern Rockies, toward northwest Ontario and the Upper Great Lakes region. At the same time, ridging appears likely to remain strong along an axis from the lower Ohio Valley through the lower Great Lakes region, with the increasingly deformed remnants of a vigorous short wave impulse migrating around its western/northern periphery, across northwestern Ontario by late Wednesday night. At 12Z Wednesday, it appears that the vigorous impulse will probably be approaching the North Dakota/Manitoba border area, with stronger associated forcing for ascent and deep-layer wind fields generally shifting north of the international border early in the day. Models indicate that this may contribute to substantive deepening of a surface cyclone migrating across Manitoba into Hudson Bay, but the trailing cold front may stall and weaken across portions of the Upper Midwest. Seasonably moist boundary layer air may linger along this front and contribute to moderately large CAPE (2000+ J/kg) with daytime heating, along a corridor through central Iowa, southeastern Minnesota and western Wisconsin by late Wednesday afternoon. While this could support the development of scattered vigorous thunderstorm activity, questions remain concerning mid-level inhibition and weak to negligible large-scale forcing for ascent. Given generally weak and/or weakening vertical shear expected across this region, the potential for severe thunderstorms still appears negligible at the present time. Elsewhere, in lower latitudes, some model guidance indicates strengthening of southerly low-level wind fields to the east of an inland migrating tropical cyclone, across the upper Texas coastal plain during this period. This could be accompanied by enlarging hodographs sufficient to support a risk for tornadoes, in the presence of tropical boundary layer moisture. At this point, however, this potential appears too low to introduce severe probabilities. ..Kerr.. 09/16/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0213 AM CDT Mon Sep 16 2019 Valid 181200Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few strong thunderstorms are possible across parts of the Upper Midwest Wednesday afternoon and evening, but the risk for severe weather currently appears negligible. ...Discussion... Within the westerlies, models indicate that amplified mid-level troughing, near the northern Pacific coast at the start of the period, will gradually dig inland through the northern and central Intermountain West and Sierra Nevada Mountains vicinity Wednesday through Wednesday night. As this occurs, large-scale downstream ridging is forecast to build east-northeast of the northern Rockies, toward northwest Ontario and the Upper Great Lakes region. At the same time, ridging appears likely to remain strong along an axis from the lower Ohio Valley through the lower Great Lakes region, with the increasingly deformed remnants of a vigorous short wave impulse migrating around its western/northern periphery, across northwestern Ontario by late Wednesday night. At 12Z Wednesday, it appears that the vigorous impulse will probably be approaching the North Dakota/Manitoba border area, with stronger associated forcing for ascent and deep-layer wind fields generally shifting north of the international border early in the day. Models indicate that this may contribute to substantive deepening of a surface cyclone migrating across Manitoba into Hudson Bay, but the trailing cold front may stall and weaken across portions of the Upper Midwest. Seasonably moist boundary layer air may linger along this front and contribute to moderately large CAPE (2000+ J/kg) with daytime heating, along a corridor through central Iowa, southeastern Minnesota and western Wisconsin by late Wednesday afternoon. While this could support the development of scattered vigorous thunderstorm activity, questions remain concerning mid-level inhibition and weak to negligible large-scale forcing for ascent. Given generally weak and/or weakening vertical shear expected across this region, the potential for severe thunderstorms still appears negligible at the present time. Elsewhere, in lower latitudes, some model guidance indicates strengthening of southerly low-level wind fields to the east of an inland migrating tropical cyclone, across the upper Texas coastal plain during this period. This could be accompanied by enlarging hodographs sufficient to support a risk for tornadoes, in the presence of tropical boundary layer moisture. At this point, however, this potential appears too low to introduce severe probabilities. ..Kerr.. 09/16/2019 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0138 AM CDT Mon Sep 16 2019 Valid 171200Z - 181200Z ...Synopsis... The upper-level trough over the western CONUS is expected to deamplify and move northeastward on Tuesday. This will weaken mid-level flow, however, some stronger flow will remain in eastern portions of the Great Basin. Therefore, a narrow corridor of elevated fire weather conditions will be possible ahead of the surface cold front on Tuesday where wind speeds are expected to be 15 to 20 mph and relative humidity is expected to be 15 to 20 percent. Elsewhere, more moist conditions and lighter winds will limit the overall fire weather threat. ..Bentley.. 09/16/2019 ...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 0138 AM CDT Mon Sep 16 2019 Valid 171200Z - 181200Z ...Synopsis... The upper-level trough over the western CONUS is expected to deamplify and move northeastward on Tuesday. This will weaken mid-level flow, however, some stronger flow will remain in eastern portions of the Great Basin. Therefore, a narrow corridor of elevated fire weather conditions will be possible ahead of the surface cold front on Tuesday where wind speeds are expected to be 15 to 20 mph and relative humidity is expected to be 15 to 20 percent. Elsewhere, more moist conditions and lighter winds will limit the overall fire weather threat. ..Bentley.. 09/16/2019 ...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 0138 AM CDT Mon Sep 16 2019 Valid 171200Z - 181200Z ...Synopsis... The upper-level trough over the western CONUS is expected to deamplify and move northeastward on Tuesday. This will weaken mid-level flow, however, some stronger flow will remain in eastern portions of the Great Basin. Therefore, a narrow corridor of elevated fire weather conditions will be possible ahead of the surface cold front on Tuesday where wind speeds are expected to be 15 to 20 mph and relative humidity is expected to be 15 to 20 percent. Elsewhere, more moist conditions and lighter winds will limit the overall fire weather threat. ..Bentley.. 09/16/2019 ...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 0138 AM CDT Mon Sep 16 2019 Valid 171200Z - 181200Z ...Synopsis... The upper-level trough over the western CONUS is expected to deamplify and move northeastward on Tuesday. This will weaken mid-level flow, however, some stronger flow will remain in eastern portions of the Great Basin. Therefore, a narrow corridor of elevated fire weather conditions will be possible ahead of the surface cold front on Tuesday where wind speeds are expected to be 15 to 20 mph and relative humidity is expected to be 15 to 20 percent. Elsewhere, more moist conditions and lighter winds will limit the overall fire weather threat. ..Bentley.. 09/16/2019 ...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 0138 AM CDT Mon Sep 16 2019 Valid 161200Z - 171200Z ...CRITICAL FIRE WEATHER AREA FOR A LARGE PORTION OF THE GREAT BASIN... ...Synopsis... A strong upper-level trough and attendant mid-level jet will overspread dry portions of the Great Basin on Monday. At the surface, dry and windy conditions are expected ahead of a cold front which will be located from western Oregon southwestward across northwest Nevada and northern California. Wind speeds are expected to range from 30 to 40 mph across east central Nevada and west central Utah with relative humidity in the 10 to 15 percent range. A large area of critical fire weather conditions is expected across most of Nevada and into western Utah. Wind speeds across this region would support extremely critical fire weather conditions, but some moisture increase from the subtropics should keep relative humidity above extremely critical thresholds. Elevated fire weather conditions will surround the critical area and extend northeastward into eastern Idaho and southwest Montana. In this region, winds are expected to be in the 20 to 25 mph range with relative humidity around 15 to 20 percent. ..Bentley.. 09/16/2019 ...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 0138 AM CDT Mon Sep 16 2019 Valid 161200Z - 171200Z ...CRITICAL FIRE WEATHER AREA FOR A LARGE PORTION OF THE GREAT BASIN... ...Synopsis... A strong upper-level trough and attendant mid-level jet will overspread dry portions of the Great Basin on Monday. At the surface, dry and windy conditions are expected ahead of a cold front which will be located from western Oregon southwestward across northwest Nevada and northern California. Wind speeds are expected to range from 30 to 40 mph across east central Nevada and west central Utah with relative humidity in the 10 to 15 percent range. A large area of critical fire weather conditions is expected across most of Nevada and into western Utah. Wind speeds across this region would support extremely critical fire weather conditions, but some moisture increase from the subtropics should keep relative humidity above extremely critical thresholds. Elevated fire weather conditions will surround the critical area and extend northeastward into eastern Idaho and southwest Montana. In this region, winds are expected to be in the 20 to 25 mph range with relative humidity around 15 to 20 percent. ..Bentley.. 09/16/2019 ...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 0138 AM CDT Mon Sep 16 2019 Valid 161200Z - 171200Z ...CRITICAL FIRE WEATHER AREA FOR A LARGE PORTION OF THE GREAT BASIN... ...Synopsis... A strong upper-level trough and attendant mid-level jet will overspread dry portions of the Great Basin on Monday. At the surface, dry and windy conditions are expected ahead of a cold front which will be located from western Oregon southwestward across northwest Nevada and northern California. Wind speeds are expected to range from 30 to 40 mph across east central Nevada and west central Utah with relative humidity in the 10 to 15 percent range. A large area of critical fire weather conditions is expected across most of Nevada and into western Utah. Wind speeds across this region would support extremely critical fire weather conditions, but some moisture increase from the subtropics should keep relative humidity above extremely critical thresholds. Elevated fire weather conditions will surround the critical area and extend northeastward into eastern Idaho and southwest Montana. In this region, winds are expected to be in the 20 to 25 mph range with relative humidity around 15 to 20 percent. ..Bentley.. 09/16/2019 ...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 0138 AM CDT Mon Sep 16 2019 Valid 161200Z - 171200Z ...CRITICAL FIRE WEATHER AREA FOR A LARGE PORTION OF THE GREAT BASIN... ...Synopsis... A strong upper-level trough and attendant mid-level jet will overspread dry portions of the Great Basin on Monday. At the surface, dry and windy conditions are expected ahead of a cold front which will be located from western Oregon southwestward across northwest Nevada and northern California. Wind speeds are expected to range from 30 to 40 mph across east central Nevada and west central Utah with relative humidity in the 10 to 15 percent range. A large area of critical fire weather conditions is expected across most of Nevada and into western Utah. Wind speeds across this region would support extremely critical fire weather conditions, but some moisture increase from the subtropics should keep relative humidity above extremely critical thresholds. Elevated fire weather conditions will surround the critical area and extend northeastward into eastern Idaho and southwest Montana. In this region, winds are expected to be in the 20 to 25 mph range with relative humidity around 15 to 20 percent. ..Bentley.. 09/16/2019 ...Please see www.spc.noaa.gov/fire for graphic product... Read more

000
ABPZ20 KNHC 160545
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
1100 PM PDT Sun Sep 15 2019

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

The National Hurricane Center is issuing advisories on Hurricane
Kiko, located nearly 1000 miles west-southwest of the southern
tip of the Baja California peninsula.

Showers and thunderstorms have increased tonight in association with
an area of low pressure centered several hundred miles
south-southwest of Manzanillo, Mexico. Conditions are conducive for
additional development, and a tropical depression could form within
the next two to three days. After mid week, this system is likely
to interact or merge with the disturbance to its east, and further
development after that time is not anticipated.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...medium...50 percent.

A large area of disorganized cloudiness and showers centered a few
hundred miles south-southwest of the Gulf of Tehuantepec is
associated with a tropical wave. Environmental conditions are
expected to be conducive for gradual development, and a tropical
depression is likely to form around the middle of the week as the
system moves west-northwestward near, or parallel to, the coast of
Mexico.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...high...70 percent.

$$
Forecaster Latto

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1153 PM CDT Sun Sep 15 2019 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TUESDAY THROUGH TUESDAY NIGHT ACROSS PARTS OF THE NORTHERN ROCKIES THROUGH MUCH OF THE NORTHERN PLAINS... ...SUMMARY... Strong thunderstorms may impact parts of the northern Rockies through much of the northern Plains Tuesday through Tuesday night, accompanied by at least some potential for severe weather. ...Synopsis... Within the westerlies, models continue to indicate substantial mid-level trough amplification near the northern Pacific coast during this period, in response to another strong, digging short wave trough and embedded closed low. As this occurs, downstream mid-level ridging is forecast to remain prominent along an axis across the Great Lakes into Hudson Bay. Within southwesterly flow between these two features, a couple of short wave impulses are expected to remain progressive. The lead impulse may undergo considerable deformation northeast of the Dakotas through northwest Ontario and the upper Great Lakes region, as it approaches the crest of the mid-level ridge. The much more vigorous upstream impulse appears likely to maintain considerable strength while accelerating northeastward out of the Great Basin through the Dakotas by 12Z Wednesday. Beneath this regime, modestly deep surface troughing, to the lee of the northern Rockies at the outset of the period, appears likely to develop eastward across the northern and central Plains, while an embedded cyclone migrates from eastern Montana into Manitoba. A trailing cold front probably will begin to overtake the surface troughing across the northern Plains by late Tuesday night. Between the surface troughing (and developing cyclone) and low/mid-level ridging to the east, it appears that confluent low-level flow, near the nose of a persistent 30-50 kt south-southwesterly 850 mb jet, will maintain seasonably moist air supportive of moderate CAPE across eastern portions of the northern Plains. While much drier boundary layer conditions are forecast to prevail across the higher Plains into the northern Rockies, daytime heating is expected to contribute to steep lapse rates and deep boundary mixing. ...Wyoming through the northern High Plains... The steepening low-level lapse rates, coupled with strong mid-level forcing for ascent and cooling in the exit region of 50-70 kt southwesterly 500 mb jet, are expected to support sufficient destabilization to initiate thunderstorm activity by midday Tuesday across the higher terrain of western into central Wyoming. As activity gradually intensifies and spreads northeastward toward the western Dakotas through early evening, sub-cloud evaporative cooling will contribute to strengthening downdrafts, aiding downward mixing of higher momentum to the surface. At least scattered strong to severe gusts appear possible, before the onset of diurnal cooling across the Plains. ...Eastern Dakotas into western Minnesota... As some combination of conglomerate convective outflow and the surface cold front surge into the more moist environment across the eastern Dakotas Tuesday evening, there appears potential for renewed vigorous thunderstorm development. Given the strength of the low-level jet, and the presence of CAPE probably in excess of 2000 J/kg, considerable upscale convective growth appears possible beneath difluent upper flow. This may be accompanied by at least some severe hail and wind risk, and spread into western Minnesota before weakening overnight. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Kerr.. 09/16/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1153 PM CDT Sun Sep 15 2019 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TUESDAY THROUGH TUESDAY NIGHT ACROSS PARTS OF THE NORTHERN ROCKIES THROUGH MUCH OF THE NORTHERN PLAINS... ...SUMMARY... Strong thunderstorms may impact parts of the northern Rockies through much of the northern Plains Tuesday through Tuesday night, accompanied by at least some potential for severe weather. ...Synopsis... Within the westerlies, models continue to indicate substantial mid-level trough amplification near the northern Pacific coast during this period, in response to another strong, digging short wave trough and embedded closed low. As this occurs, downstream mid-level ridging is forecast to remain prominent along an axis across the Great Lakes into Hudson Bay. Within southwesterly flow between these two features, a couple of short wave impulses are expected to remain progressive. The lead impulse may undergo considerable deformation northeast of the Dakotas through northwest Ontario and the upper Great Lakes region, as it approaches the crest of the mid-level ridge. The much more vigorous upstream impulse appears likely to maintain considerable strength while accelerating northeastward out of the Great Basin through the Dakotas by 12Z Wednesday. Beneath this regime, modestly deep surface troughing, to the lee of the northern Rockies at the outset of the period, appears likely to develop eastward across the northern and central Plains, while an embedded cyclone migrates from eastern Montana into Manitoba. A trailing cold front probably will begin to overtake the surface troughing across the northern Plains by late Tuesday night. Between the surface troughing (and developing cyclone) and low/mid-level ridging to the east, it appears that confluent low-level flow, near the nose of a persistent 30-50 kt south-southwesterly 850 mb jet, will maintain seasonably moist air supportive of moderate CAPE across eastern portions of the northern Plains. While much drier boundary layer conditions are forecast to prevail across the higher Plains into the northern Rockies, daytime heating is expected to contribute to steep lapse rates and deep boundary mixing. ...Wyoming through the northern High Plains... The steepening low-level lapse rates, coupled with strong mid-level forcing for ascent and cooling in the exit region of 50-70 kt southwesterly 500 mb jet, are expected to support sufficient destabilization to initiate thunderstorm activity by midday Tuesday across the higher terrain of western into central Wyoming. As activity gradually intensifies and spreads northeastward toward the western Dakotas through early evening, sub-cloud evaporative cooling will contribute to strengthening downdrafts, aiding downward mixing of higher momentum to the surface. At least scattered strong to severe gusts appear possible, before the onset of diurnal cooling across the Plains. ...Eastern Dakotas into western Minnesota... As some combination of conglomerate convective outflow and the surface cold front surge into the more moist environment across the eastern Dakotas Tuesday evening, there appears potential for renewed vigorous thunderstorm development. Given the strength of the low-level jet, and the presence of CAPE probably in excess of 2000 J/kg, considerable upscale convective growth appears possible beneath difluent upper flow. This may be accompanied by at least some severe hail and wind risk, and spread into western Minnesota before weakening overnight. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Kerr.. 09/16/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1153 PM CDT Sun Sep 15 2019 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TUESDAY THROUGH TUESDAY NIGHT ACROSS PARTS OF THE NORTHERN ROCKIES THROUGH MUCH OF THE NORTHERN PLAINS... ...SUMMARY... Strong thunderstorms may impact parts of the northern Rockies through much of the northern Plains Tuesday through Tuesday night, accompanied by at least some potential for severe weather. ...Synopsis... Within the westerlies, models continue to indicate substantial mid-level trough amplification near the northern Pacific coast during this period, in response to another strong, digging short wave trough and embedded closed low. As this occurs, downstream mid-level ridging is forecast to remain prominent along an axis across the Great Lakes into Hudson Bay. Within southwesterly flow between these two features, a couple of short wave impulses are expected to remain progressive. The lead impulse may undergo considerable deformation northeast of the Dakotas through northwest Ontario and the upper Great Lakes region, as it approaches the crest of the mid-level ridge. The much more vigorous upstream impulse appears likely to maintain considerable strength while accelerating northeastward out of the Great Basin through the Dakotas by 12Z Wednesday. Beneath this regime, modestly deep surface troughing, to the lee of the northern Rockies at the outset of the period, appears likely to develop eastward across the northern and central Plains, while an embedded cyclone migrates from eastern Montana into Manitoba. A trailing cold front probably will begin to overtake the surface troughing across the northern Plains by late Tuesday night. Between the surface troughing (and developing cyclone) and low/mid-level ridging to the east, it appears that confluent low-level flow, near the nose of a persistent 30-50 kt south-southwesterly 850 mb jet, will maintain seasonably moist air supportive of moderate CAPE across eastern portions of the northern Plains. While much drier boundary layer conditions are forecast to prevail across the higher Plains into the northern Rockies, daytime heating is expected to contribute to steep lapse rates and deep boundary mixing. ...Wyoming through the northern High Plains... The steepening low-level lapse rates, coupled with strong mid-level forcing for ascent and cooling in the exit region of 50-70 kt southwesterly 500 mb jet, are expected to support sufficient destabilization to initiate thunderstorm activity by midday Tuesday across the higher terrain of western into central Wyoming. As activity gradually intensifies and spreads northeastward toward the western Dakotas through early evening, sub-cloud evaporative cooling will contribute to strengthening downdrafts, aiding downward mixing of higher momentum to the surface. At least scattered strong to severe gusts appear possible, before the onset of diurnal cooling across the Plains. ...Eastern Dakotas into western Minnesota... As some combination of conglomerate convective outflow and the surface cold front surge into the more moist environment across the eastern Dakotas Tuesday evening, there appears potential for renewed vigorous thunderstorm development. Given the strength of the low-level jet, and the presence of CAPE probably in excess of 2000 J/kg, considerable upscale convective growth appears possible beneath difluent upper flow. This may be accompanied by at least some severe hail and wind risk, and spread into western Minnesota before weakening overnight. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Kerr.. 09/16/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1153 PM CDT Sun Sep 15 2019 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TUESDAY THROUGH TUESDAY NIGHT ACROSS PARTS OF THE NORTHERN ROCKIES THROUGH MUCH OF THE NORTHERN PLAINS... ...SUMMARY... Strong thunderstorms may impact parts of the northern Rockies through much of the northern Plains Tuesday through Tuesday night, accompanied by at least some potential for severe weather. ...Synopsis... Within the westerlies, models continue to indicate substantial mid-level trough amplification near the northern Pacific coast during this period, in response to another strong, digging short wave trough and embedded closed low. As this occurs, downstream mid-level ridging is forecast to remain prominent along an axis across the Great Lakes into Hudson Bay. Within southwesterly flow between these two features, a couple of short wave impulses are expected to remain progressive. The lead impulse may undergo considerable deformation northeast of the Dakotas through northwest Ontario and the upper Great Lakes region, as it approaches the crest of the mid-level ridge. The much more vigorous upstream impulse appears likely to maintain considerable strength while accelerating northeastward out of the Great Basin through the Dakotas by 12Z Wednesday. Beneath this regime, modestly deep surface troughing, to the lee of the northern Rockies at the outset of the period, appears likely to develop eastward across the northern and central Plains, while an embedded cyclone migrates from eastern Montana into Manitoba. A trailing cold front probably will begin to overtake the surface troughing across the northern Plains by late Tuesday night. Between the surface troughing (and developing cyclone) and low/mid-level ridging to the east, it appears that confluent low-level flow, near the nose of a persistent 30-50 kt south-southwesterly 850 mb jet, will maintain seasonably moist air supportive of moderate CAPE across eastern portions of the northern Plains. While much drier boundary layer conditions are forecast to prevail across the higher Plains into the northern Rockies, daytime heating is expected to contribute to steep lapse rates and deep boundary mixing. ...Wyoming through the northern High Plains... The steepening low-level lapse rates, coupled with strong mid-level forcing for ascent and cooling in the exit region of 50-70 kt southwesterly 500 mb jet, are expected to support sufficient destabilization to initiate thunderstorm activity by midday Tuesday across the higher terrain of western into central Wyoming. As activity gradually intensifies and spreads northeastward toward the western Dakotas through early evening, sub-cloud evaporative cooling will contribute to strengthening downdrafts, aiding downward mixing of higher momentum to the surface. At least scattered strong to severe gusts appear possible, before the onset of diurnal cooling across the Plains. ...Eastern Dakotas into western Minnesota... As some combination of conglomerate convective outflow and the surface cold front surge into the more moist environment across the eastern Dakotas Tuesday evening, there appears potential for renewed vigorous thunderstorm development. Given the strength of the low-level jet, and the presence of CAPE probably in excess of 2000 J/kg, considerable upscale convective growth appears possible beneath difluent upper flow. This may be accompanied by at least some severe hail and wind risk, and spread into western Minnesota before weakening overnight. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Kerr.. 09/16/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1210 AM CDT Mon Sep 16 2019 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHERN AND CENTRAL UTAH THIS AFTERNOON INTO TONIGHT... ...SUMMARY... A few thunderstorms with locally strong wind gusts may impact portions of northern and central Utah this afternoon into tonight. ...Utah/Great Basin Vicinity... A shortwave trough approaching the Pacific coast early this morning will continue to progress eastward across the Great Basin through the forecast period. Residual midlevel moisture should be sufficient for a few diurnally driven thunderstorms across eastern AZ/UT as forcing increases with the approach of the upper trough. However, effective shear will remain weak despite increasing speed shear for much of the period. This will limit severe potential for much of the day, though a well-mixed sub-cloud layer producing inverted-v type thermodynamic profiles could support some locally gusty winds. Overnight, shear profiles will improve as the trough impinges on the area and a surface cold front sweeps southeast across ID/NV/CA and into UT after around 06z. Instability will be limited, but guidance continues to suggest a weak convective line associated with the front moving across parts of northern/central UT overnight. Given the strength of the background wind field and the dry sub-cloud layer, some downward momentum transport could result in a couple of severe wind gusts associated with weak convection. ..Leitman/Bentley.. 09/16/2019 Read more