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SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Sun Sep 08 2019 Valid 081300Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL HIGH PLAINS AND COLORADO FRONT RANGE FOOTHILLS CORRIDOR... ...SUMMARY... Severe thunderstorms with strong/gusty winds and hail will be possible across parts of the central Rockies and adjacent High Plains this afternoon and evening. ...Synopsis... In mid/upper levels, the main convective influence this period will be a negatively tilted trough -- now apparent in moisture-channel imagery from near the mouth of the Columbia River across western/ southern OR, western NV, and the lower Colorado River Valley of AZ/CA. Led by several associated small-scale vorticity lobes, this trough should reach ID, northern UT and northern/central AZ by 00Z. By 12Z, the trough should extend from north-central MT down the central Rockies of WY/CO, with leading vorticity maxima ejecting northeastward across portions of NE/Dakotas. This will occur as a zonally elongated cyclone -- now located offshore from Vancouver Island, Canada -- becomes somewhat more axisymmetric and expansive, moving onshore of the Pacific Northwest and BC around the end of the period. At the surface, a cold front was analyzed from southern QC southwestward across western Lake Erie and north-central IN, becoming ill-defined in and overtaken by convective outflow southwestward across northern MO and central/southern KS, where the outflow boundaries act as the effective front. Another frontal zone was drawn from the Hampton Roads area southwestward across eastern NC to a weak frontal-wave low over east-central SC, then west- northwestward over northern portions of GA/AL/MS, then north- northwestward across the Mid-South to south-central MO, intersecting some of the aforementioned outflow there. The combined frontal/ outflow baroclinic zone will consolidate today as a warm front moving slowly northward across central/northern MO, northern KS, extreme southern NE, and the northeastern CO/southwestern NE area. Meanwhile, a currently weak lee trough will become more sharply defined across central MT, north-central/eastern WY, and eastern CO. ...Central Rockies/High Plains... Scattered thunderstorms will develop over the western mountains of CO as early as midday, possibly as an extension of the same convective/vertical-motion plume now apparent over UT. This activity and the related/surrounding plume of large-scale ascent should move east-northeastward to northeastward, impinging upon the moister, diabatically destabilized Front Range/Laramie Range region between 21-00Z. As this occurs, a mix of discrete, clustered and quasi-linear modes is possible, with ultimate evolution of a band of strong-severe thunderstorms across the Foothills and adjoining High Plains from late afternoon into the evening. Given the steep low/middle-level lapse rates anticipated, at least marginal inflow-layer moisture content and somewhat supercell- favorable deep shear, isolated large hail is possible, especially from any discrete/semi-discrete cells. However, the main threat will be severe gusts. Well-mixed subcloud/inflow layers from the foothills across the adjoining plains will develop beneath 1000-1500 J/kg MLCAPE, leading to "inverted-v" thermodynamic profiles supporting downdraft acceleration. This, combined with expected coalescence of the bulk of convection into quasi-linear mode sweeping northeastward over the outlook area, indicate wind as the principal concern. ..Edwards/Smith.. 09/08/2019 Read more

SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0753 AM CDT Sun Sep 08 2019 Valid 081300Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL HIGH PLAINS AND COLORADO FRONT RANGE FOOTHILLS CORRIDOR... ...SUMMARY... Severe thunderstorms with strong/gusty winds and hail will be possible across parts of the central Rockies and adjacent High Plains this afternoon and evening. ...Synopsis... In mid/upper levels, the main convective influence this period will be a negatively tilted trough -- now apparent in moisture-channel imagery from near the mouth of the Columbia River across western/ southern OR, western NV, and the lower Colorado River Valley of AZ/CA. Led by several associated small-scale vorticity lobes, this trough should reach ID, northern UT and northern/central AZ by 00Z. By 12Z, the trough should extend from north-central MT down the central Rockies of WY/CO, with leading vorticity maxima ejecting northeastward across portions of NE/Dakotas. This will occur as a zonally elongated cyclone -- now located offshore from Vancouver Island, Canada -- becomes somewhat more axisymmetric and expansive, moving onshore of the Pacific Northwest and BC around the end of the period. At the surface, a cold front was analyzed from southern QC southwestward across western Lake Erie and north-central IN, becoming ill-defined in and overtaken by convective outflow southwestward across northern MO and central/southern KS, where the outflow boundaries act as the effective front. Another frontal zone was drawn from the Hampton Roads area southwestward across eastern NC to a weak frontal-wave low over east-central SC, then west- northwestward over northern portions of GA/AL/MS, then north- northwestward across the Mid-South to south-central MO, intersecting some of the aforementioned outflow there. The combined frontal/ outflow baroclinic zone will consolidate today as a warm front moving slowly northward across central/northern MO, northern KS, extreme southern NE, and the northeastern CO/southwestern NE area. Meanwhile, a currently weak lee trough will become more sharply defined across central MT, north-central/eastern WY, and eastern CO. ...Central Rockies/High Plains... Scattered thunderstorms will develop over the western mountains of CO as early as midday, possibly as an extension of the same convective/vertical-motion plume now apparent over UT. This activity and the related/surrounding plume of large-scale ascent should move east-northeastward to northeastward, impinging upon the moister, diabatically destabilized Front Range/Laramie Range region between 21-00Z. As this occurs, a mix of discrete, clustered and quasi-linear modes is possible, with ultimate evolution of a band of strong-severe thunderstorms across the Foothills and adjoining High Plains from late afternoon into the evening. Given the steep low/middle-level lapse rates anticipated, at least marginal inflow-layer moisture content and somewhat supercell- favorable deep shear, isolated large hail is possible, especially from any discrete/semi-discrete cells. However, the main threat will be severe gusts. Well-mixed subcloud/inflow layers from the foothills across the adjoining plains will develop beneath 1000-1500 J/kg MLCAPE, leading to "inverted-v" thermodynamic profiles supporting downdraft acceleration. This, combined with expected coalescence of the bulk of convection into quasi-linear mode sweeping northeastward over the outlook area, indicate wind as the principal concern. ..Edwards/Smith.. 09/08/2019 Read more

149
ABPZ20 KNHC 081116
TWOEP

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
500 AM PDT Sun Sep 8 2019

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

An area of low pressure is expected to form in a few days well to
the southwest of the southern coast of Mexico. Environmental
conditions appear conducive for gradual development, and a tropical
depression could form by the middle of the week while the low moves
west-northwestward at around 10 mph.
* Formation chance through 48 hours...low...near 0 percent.
* Formation chance through 5 days...medium...50 percent.

$$
Forecaster Latto

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CDT Sun Sep 08 2019 Valid 111200Z - 161200Z ...DISCUSSION... ...Wednesday/Day 4 and Thursday/Day 5... The medium-range models including the ECMWF, GFS, Canadian and UKMET are in reasonably good agreement on Wednesday. These solutions move an upper-level trough into the Four Corners region as southwest mid-level flow remains over the north-central U.S. The models develop a pocket of moderate instability across northeastern Nebraska and southeastern South Dakota Wednesday afternoon. A 15 percent contour has been added across this area where forecast deep-layer shear appears strong enough for severe storm development. The upper-level trough is forecast to move across the Great Plains on Thursday as a cold front advances eastward into the Upper Mississippi and mid Missouri Valleys. An isolated severe threat would be possible along and just ahead of the front as instability becomes maximized late Thursday afternoon. The exact timing of the front is too uncertain to add a threat area at this time. ...Friday/Day 6 to Sunday/Day 8... On Friday and Saturday, the models move the upper-level trough across the Great Lakes and Northeast as another upper-level trough develops in the western U.S. Low-level moisture return may take place Friday night into Saturday across parts of the north-central states. It appears that a severe threat will be possible Saturday afternoon across the eastern part of the northern Plains where instability and deep-layer shear is forecast to be maximized. On Sunday, the model solutions vary considerably suggesting that uncertainty is substantial concerning a severe threat. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CDT Sun Sep 08 2019 Valid 111200Z - 161200Z ...DISCUSSION... ...Wednesday/Day 4 and Thursday/Day 5... The medium-range models including the ECMWF, GFS, Canadian and UKMET are in reasonably good agreement on Wednesday. These solutions move an upper-level trough into the Four Corners region as southwest mid-level flow remains over the north-central U.S. The models develop a pocket of moderate instability across northeastern Nebraska and southeastern South Dakota Wednesday afternoon. A 15 percent contour has been added across this area where forecast deep-layer shear appears strong enough for severe storm development. The upper-level trough is forecast to move across the Great Plains on Thursday as a cold front advances eastward into the Upper Mississippi and mid Missouri Valleys. An isolated severe threat would be possible along and just ahead of the front as instability becomes maximized late Thursday afternoon. The exact timing of the front is too uncertain to add a threat area at this time. ...Friday/Day 6 to Sunday/Day 8... On Friday and Saturday, the models move the upper-level trough across the Great Lakes and Northeast as another upper-level trough develops in the western U.S. Low-level moisture return may take place Friday night into Saturday across parts of the north-central states. It appears that a severe threat will be possible Saturday afternoon across the eastern part of the northern Plains where instability and deep-layer shear is forecast to be maximized. On Sunday, the model solutions vary considerably suggesting that uncertainty is substantial concerning a severe threat. Read more

Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0347 AM CDT Sun Sep 08 2019 Valid 111200Z - 161200Z ...DISCUSSION... ...Wednesday/Day 4 and Thursday/Day 5... The medium-range models including the ECMWF, GFS, Canadian and UKMET are in reasonably good agreement on Wednesday. These solutions move an upper-level trough into the Four Corners region as southwest mid-level flow remains over the north-central U.S. The models develop a pocket of moderate instability across northeastern Nebraska and southeastern South Dakota Wednesday afternoon. A 15 percent contour has been added across this area where forecast deep-layer shear appears strong enough for severe storm development. The upper-level trough is forecast to move across the Great Plains on Thursday as a cold front advances eastward into the Upper Mississippi and mid Missouri Valleys. An isolated severe threat would be possible along and just ahead of the front as instability becomes maximized late Thursday afternoon. The exact timing of the front is too uncertain to add a threat area at this time. ...Friday/Day 6 to Sunday/Day 8... On Friday and Saturday, the models move the upper-level trough across the Great Lakes and Northeast as another upper-level trough develops in the western U.S. Low-level moisture return may take place Friday night into Saturday across parts of the north-central states. It appears that a severe threat will be possible Saturday afternoon across the eastern part of the northern Plains where instability and deep-layer shear is forecast to be maximized. On Sunday, the model solutions vary considerably suggesting that uncertainty is substantial concerning a severe threat. Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0214 AM CDT Sun Sep 08 2019 Valid 101200Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS... ...SUMMARY... Thunderstorms associated with isolated severe wind gusts and hail will be possible across parts of the central and northern Plains on Tuesday. ...Central and Northern Plains... A shortwave ridge is forecast to move across the northern Plains on Tuesday as southwest mid-level flow becomes established across the central Plains. At the surface, a lee trough is forecast to deepen across the central High Plains as a corridor of maximized low-level moisture sets up from Nebraska into Iowa. Model forecasts develop a pocket of moderate instability by afternoon and increase low-level convergence on the northern edge of the strongest instability. Surface-based convection may develop along this zone of convergence during the afternoon and early evening. Deep-layer shear is forecast to reach the 40 to 50 kt range suggesting supercells will be possible. Any supercell would have potential for isolated large hail and wind damage. The main uncertainty for this forecast is cell coverage. At this point, cell coverage is expected to remain isolated so a marginal risk will suffice. ..Broyles.. 09/08/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0214 AM CDT Sun Sep 08 2019 Valid 101200Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS... ...SUMMARY... Thunderstorms associated with isolated severe wind gusts and hail will be possible across parts of the central and northern Plains on Tuesday. ...Central and Northern Plains... A shortwave ridge is forecast to move across the northern Plains on Tuesday as southwest mid-level flow becomes established across the central Plains. At the surface, a lee trough is forecast to deepen across the central High Plains as a corridor of maximized low-level moisture sets up from Nebraska into Iowa. Model forecasts develop a pocket of moderate instability by afternoon and increase low-level convergence on the northern edge of the strongest instability. Surface-based convection may develop along this zone of convergence during the afternoon and early evening. Deep-layer shear is forecast to reach the 40 to 50 kt range suggesting supercells will be possible. Any supercell would have potential for isolated large hail and wind damage. The main uncertainty for this forecast is cell coverage. At this point, cell coverage is expected to remain isolated so a marginal risk will suffice. ..Broyles.. 09/08/2019 Read more

SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0214 AM CDT Sun Sep 08 2019 Valid 101200Z - 111200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL PLAINS... ...SUMMARY... Thunderstorms associated with isolated severe wind gusts and hail will be possible across parts of the central and northern Plains on Tuesday. ...Central and Northern Plains... A shortwave ridge is forecast to move across the northern Plains on Tuesday as southwest mid-level flow becomes established across the central Plains. At the surface, a lee trough is forecast to deepen across the central High Plains as a corridor of maximized low-level moisture sets up from Nebraska into Iowa. Model forecasts develop a pocket of moderate instability by afternoon and increase low-level convergence on the northern edge of the strongest instability. Surface-based convection may develop along this zone of convergence during the afternoon and early evening. Deep-layer shear is forecast to reach the 40 to 50 kt range suggesting supercells will be possible. Any supercell would have potential for isolated large hail and wind damage. The main uncertainty for this forecast is cell coverage. At this point, cell coverage is expected to remain isolated so a marginal risk will suffice. ..Broyles.. 09/08/2019 Read more

SPC Day 2 Fire Weather Outlook
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0148 AM CDT Sun Sep 08 2019 Valid 091200Z - 101200Z ...Synopsis... Mid/upper-level longwave troughing is forecast to remain/deepen over much of the western CONUS Day 2/Monday. As this occurs, an area of enhanced mid-level flow is forecast to overspread portions of southern California, the Southwest, and the southern Great Basin. ...Nevada/Utah/Arizona... Downward mixing of the aforementioned enhanced mid-level flow should foster sustained surface winds of 15-20 mph (locally greater) Day 2/Monday afternoon/evening over portions of the southern Great Basin and vicinity. Elevated to locally critical fire weather conditions are forecast to develop as these surface winds overlap near-critical RH values and at least marginally receptive fuels. At this time, uncertainty regarding coverage/duration of sustained surface winds > 20 mph and critically-lowered RH values precludes the introduction of a critical fire weather area. ...Southern California: Santa Barbara and western Ventura County... Elevated fire weather conditions may be ongoing at higher elevations (e.g., > 1 kft) of eastern Santa Barbara and western Ventura Counties at 12Z Day 2/Monday due to poor overnight RH recoveries and gusty Sundowner winds. While surface winds are forecast to weaken and become less gusty during the late morning and early afternoon, elevated fire weather conditions are expected to redevelop as surface winds increase during the afternoon/evening. Elevated fire weather conditions may continue through the Day 2/Monday overnight as poor overnight RH recoveries and gusty winds persist. ..Elliott.. 09/08/2019 ...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 0148 AM CDT Sun Sep 08 2019 Valid 091200Z - 101200Z ...Synopsis... Mid/upper-level longwave troughing is forecast to remain/deepen over much of the western CONUS Day 2/Monday. As this occurs, an area of enhanced mid-level flow is forecast to overspread portions of southern California, the Southwest, and the southern Great Basin. ...Nevada/Utah/Arizona... Downward mixing of the aforementioned enhanced mid-level flow should foster sustained surface winds of 15-20 mph (locally greater) Day 2/Monday afternoon/evening over portions of the southern Great Basin and vicinity. Elevated to locally critical fire weather conditions are forecast to develop as these surface winds overlap near-critical RH values and at least marginally receptive fuels. At this time, uncertainty regarding coverage/duration of sustained surface winds > 20 mph and critically-lowered RH values precludes the introduction of a critical fire weather area. ...Southern California: Santa Barbara and western Ventura County... Elevated fire weather conditions may be ongoing at higher elevations (e.g., > 1 kft) of eastern Santa Barbara and western Ventura Counties at 12Z Day 2/Monday due to poor overnight RH recoveries and gusty Sundowner winds. While surface winds are forecast to weaken and become less gusty during the late morning and early afternoon, elevated fire weather conditions are expected to redevelop as surface winds increase during the afternoon/evening. Elevated fire weather conditions may continue through the Day 2/Monday overnight as poor overnight RH recoveries and gusty winds persist. ..Elliott.. 09/08/2019 ...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 0148 AM CDT Sun Sep 08 2019 Valid 091200Z - 101200Z ...Synopsis... Mid/upper-level longwave troughing is forecast to remain/deepen over much of the western CONUS Day 2/Monday. As this occurs, an area of enhanced mid-level flow is forecast to overspread portions of southern California, the Southwest, and the southern Great Basin. ...Nevada/Utah/Arizona... Downward mixing of the aforementioned enhanced mid-level flow should foster sustained surface winds of 15-20 mph (locally greater) Day 2/Monday afternoon/evening over portions of the southern Great Basin and vicinity. Elevated to locally critical fire weather conditions are forecast to develop as these surface winds overlap near-critical RH values and at least marginally receptive fuels. At this time, uncertainty regarding coverage/duration of sustained surface winds > 20 mph and critically-lowered RH values precludes the introduction of a critical fire weather area. ...Southern California: Santa Barbara and western Ventura County... Elevated fire weather conditions may be ongoing at higher elevations (e.g., > 1 kft) of eastern Santa Barbara and western Ventura Counties at 12Z Day 2/Monday due to poor overnight RH recoveries and gusty Sundowner winds. While surface winds are forecast to weaken and become less gusty during the late morning and early afternoon, elevated fire weather conditions are expected to redevelop as surface winds increase during the afternoon/evening. Elevated fire weather conditions may continue through the Day 2/Monday overnight as poor overnight RH recoveries and gusty winds persist. ..Elliott.. 09/08/2019 ...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 1252 AM CDT Sun Sep 08 2019 Valid 081200Z - 091200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHEASTERN UTAH... ...Synopsis... A mid-level shortwave trough -- embedded near the base of a longer wavelength mid/upper-level trough located over much of the western CONUS -- is forecast to move from the Great Basin into the central/northern Rockies today/tonight. ...Southwest into the southern Great Basin... An area of enhanced mid-level flow, associated with the aforementioned shortwave trough, is forecast to overspread portions of southern Nevada/Utah and northern Arizona this afternoon and evening. Relatively steep low-level lapse rates should allow for efficient downward mixing of these stronger winds from aloft, with sustained winds of 15-25 mph amidst near critical RH values (e.g., around 15%). Critical conditions still appear most probable across southeast Utah, where the timing of the enhanced flow aloft best coincides with peak heating and minimum RH reductions. While near-critical conditions are possible outside of the critical fire weather area -- mainly across west/southwest Utah and northern Arizona -- uncertainty regarding the extent/duration of critical conditions in these areas precludes a critical designation at this time. ...Southern California... Elevated to locally critical conditions are forecast to be ongoing -- mainly at elevations > 1 kft -- this morning from Santa Barbara County southward toward the San Diego County mountains due to poor overnight RH recoveries and gusty surface winds (locally 40+ mph). Surface winds should generally weaken and become less gusty this morning and early afternoon, before increasing again by mid-afternoon with elevated fire weather conditions redeveloping (especially over Santa Barbara, eastern Ventura, and western Los Angeles Counties). Poor overnight RH recoveries and lingering gusty winds may allow elevated fire weather conditions to persist through the overnight. ..Elliott.. 09/08/2019 ...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 1252 AM CDT Sun Sep 08 2019 Valid 081200Z - 091200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHEASTERN UTAH... ...Synopsis... A mid-level shortwave trough -- embedded near the base of a longer wavelength mid/upper-level trough located over much of the western CONUS -- is forecast to move from the Great Basin into the central/northern Rockies today/tonight. ...Southwest into the southern Great Basin... An area of enhanced mid-level flow, associated with the aforementioned shortwave trough, is forecast to overspread portions of southern Nevada/Utah and northern Arizona this afternoon and evening. Relatively steep low-level lapse rates should allow for efficient downward mixing of these stronger winds from aloft, with sustained winds of 15-25 mph amidst near critical RH values (e.g., around 15%). Critical conditions still appear most probable across southeast Utah, where the timing of the enhanced flow aloft best coincides with peak heating and minimum RH reductions. While near-critical conditions are possible outside of the critical fire weather area -- mainly across west/southwest Utah and northern Arizona -- uncertainty regarding the extent/duration of critical conditions in these areas precludes a critical designation at this time. ...Southern California... Elevated to locally critical conditions are forecast to be ongoing -- mainly at elevations > 1 kft -- this morning from Santa Barbara County southward toward the San Diego County mountains due to poor overnight RH recoveries and gusty surface winds (locally 40+ mph). Surface winds should generally weaken and become less gusty this morning and early afternoon, before increasing again by mid-afternoon with elevated fire weather conditions redeveloping (especially over Santa Barbara, eastern Ventura, and western Los Angeles Counties). Poor overnight RH recoveries and lingering gusty winds may allow elevated fire weather conditions to persist through the overnight. ..Elliott.. 09/08/2019 ...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 1252 AM CDT Sun Sep 08 2019 Valid 081200Z - 091200Z ...CRITICAL FIRE WEATHER AREA FOR SOUTHEASTERN UTAH... ...Synopsis... A mid-level shortwave trough -- embedded near the base of a longer wavelength mid/upper-level trough located over much of the western CONUS -- is forecast to move from the Great Basin into the central/northern Rockies today/tonight. ...Southwest into the southern Great Basin... An area of enhanced mid-level flow, associated with the aforementioned shortwave trough, is forecast to overspread portions of southern Nevada/Utah and northern Arizona this afternoon and evening. Relatively steep low-level lapse rates should allow for efficient downward mixing of these stronger winds from aloft, with sustained winds of 15-25 mph amidst near critical RH values (e.g., around 15%). Critical conditions still appear most probable across southeast Utah, where the timing of the enhanced flow aloft best coincides with peak heating and minimum RH reductions. While near-critical conditions are possible outside of the critical fire weather area -- mainly across west/southwest Utah and northern Arizona -- uncertainty regarding the extent/duration of critical conditions in these areas precludes a critical designation at this time. ...Southern California... Elevated to locally critical conditions are forecast to be ongoing -- mainly at elevations > 1 kft -- this morning from Santa Barbara County southward toward the San Diego County mountains due to poor overnight RH recoveries and gusty surface winds (locally 40+ mph). Surface winds should generally weaken and become less gusty this morning and early afternoon, before increasing again by mid-afternoon with elevated fire weather conditions redeveloping (especially over Santa Barbara, eastern Ventura, and western Los Angeles Counties). Poor overnight RH recoveries and lingering gusty winds may allow elevated fire weather conditions to persist through the overnight. ..Elliott.. 09/08/2019 ...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 1248 AM CDT Sun Sep 08 2019 Valid 091200Z - 101200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY... ...SUMMARY... Thunderstorms associated with hail and marginally severe wind gusts will be possible on Monday across parts of the central and northern Plains eastward into the upper Mississippi Valley. ...Central and Northern Plains/Upper Mississippi Valley... A shortwave ridge will move into the Great Lakes region on Monday as a shortwave trough moves across the Northern Plains. At the surface, a low is forecast to deepen across South Dakota as a warm front advances northeastward into the upper Mississippi Valley. Elevated thunderstorms will be possible to the north of the warm front across parts of Minnesota and Wisconsin during the day. A corridor of maximized low-level moisture (dewpoints of 68 to 72 F) should be in place to the east of the surface low from eastern South Dakota southeastward into Iowa. This corridor will be the preferred area for surface-based convection during the afternoon. NAM forecast soundings along and just south of the warm front at 00Z/Tuesday show MLCAPE mostly in the 1500 to 2500 J/kg range. 0-6 km shear is forecast to be from 35 to 45 kt suggesting supercells will be possible. Supercells would be capable of large hail and wind damage. As the warm front moves northeastward, the strongest instability will translate quickly northeastward across the mid Missouri Valley. For this reason, the timing of the shortwave trough will be very important to the placement of the greatest severe threat. For this reason, a marginal risk area will suffice for this forecast until confidence increases concerning the finer-scale details of the scenario. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Broyles.. 09/08/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Sun Sep 08 2019 Valid 091200Z - 101200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY... ...SUMMARY... Thunderstorms associated with hail and marginally severe wind gusts will be possible on Monday across parts of the central and northern Plains eastward into the upper Mississippi Valley. ...Central and Northern Plains/Upper Mississippi Valley... A shortwave ridge will move into the Great Lakes region on Monday as a shortwave trough moves across the Northern Plains. At the surface, a low is forecast to deepen across South Dakota as a warm front advances northeastward into the upper Mississippi Valley. Elevated thunderstorms will be possible to the north of the warm front across parts of Minnesota and Wisconsin during the day. A corridor of maximized low-level moisture (dewpoints of 68 to 72 F) should be in place to the east of the surface low from eastern South Dakota southeastward into Iowa. This corridor will be the preferred area for surface-based convection during the afternoon. NAM forecast soundings along and just south of the warm front at 00Z/Tuesday show MLCAPE mostly in the 1500 to 2500 J/kg range. 0-6 km shear is forecast to be from 35 to 45 kt suggesting supercells will be possible. Supercells would be capable of large hail and wind damage. As the warm front moves northeastward, the strongest instability will translate quickly northeastward across the mid Missouri Valley. For this reason, the timing of the shortwave trough will be very important to the placement of the greatest severe threat. For this reason, a marginal risk area will suffice for this forecast until confidence increases concerning the finer-scale details of the scenario. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Broyles.. 09/08/2019 Read more

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1248 AM CDT Sun Sep 08 2019 Valid 091200Z - 101200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY... ...SUMMARY... Thunderstorms associated with hail and marginally severe wind gusts will be possible on Monday across parts of the central and northern Plains eastward into the upper Mississippi Valley. ...Central and Northern Plains/Upper Mississippi Valley... A shortwave ridge will move into the Great Lakes region on Monday as a shortwave trough moves across the Northern Plains. At the surface, a low is forecast to deepen across South Dakota as a warm front advances northeastward into the upper Mississippi Valley. Elevated thunderstorms will be possible to the north of the warm front across parts of Minnesota and Wisconsin during the day. A corridor of maximized low-level moisture (dewpoints of 68 to 72 F) should be in place to the east of the surface low from eastern South Dakota southeastward into Iowa. This corridor will be the preferred area for surface-based convection during the afternoon. NAM forecast soundings along and just south of the warm front at 00Z/Tuesday show MLCAPE mostly in the 1500 to 2500 J/kg range. 0-6 km shear is forecast to be from 35 to 45 kt suggesting supercells will be possible. Supercells would be capable of large hail and wind damage. As the warm front moves northeastward, the strongest instability will translate quickly northeastward across the mid Missouri Valley. For this reason, the timing of the shortwave trough will be very important to the placement of the greatest severe threat. For this reason, a marginal risk area will suffice for this forecast until confidence increases concerning the finer-scale details of the scenario. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 5% - Marginal Hail: 5% - Marginal ..Broyles.. 09/08/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1225 AM CDT Sun Sep 08 2019 Valid 081200Z - 091200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS CENTERED OVER THE CENTRAL HIGH PLAINS REGION... ...SUMMARY... Isolated severe thunderstorms with strong/gusty winds and hail will be possible across parts of the central Rockies and adjacent High Plains Sunday afternoon and evening. ...Synopsis... Cyclonic flow aloft will diminish over the northeastern U.S., as a low shifts northeastward across the Canadian Maritimes. In the West, a lead trough is forecast to shift east across the Intermountain West, eventually reaching the high Plains, ahead of a larger trough/low expected to move gradually onshore over the West Coast. In between the western and northeastern troughing, low-amplitude ridging will cross the central U.S. through the period. At the surface, a weak baroclinic zone will lie east to west across Missouri and Kansas, and then northwestward along the high Plains. As the upper system advances across the Rockies, a weak/elongated frontal low is forecast to gradually develop, centered over the northeastern Wyoming vicinity. ...Central High Plains vicinity... As the upper trough crosses the West, showers and thunderstorms are forecast to increase in coverage through the day across a broad portion of the Intermountain region. As increasing ascent begins reaching the high Plains during the afternoon, where low-level southeasterly flow is expected to maintain a slightly more moist low-level airmass, the more favorable instability will support an increase in storm coverage and intensity. The approach of the upper system will also bring a modest increase in flow aloft, likely supporting a progression of convection off the higher terrain and across the central high Plains -- possibly evolving into a semi-organized band or bands into the evening hours. This evolution will correspond with some potential for gusty/locally damaging winds, and possibly marginal hail through the evening hours. ..Goss/Elliott.. 09/08/2019 Read more

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1225 AM CDT Sun Sep 08 2019 Valid 081200Z - 091200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS CENTERED OVER THE CENTRAL HIGH PLAINS REGION... ...SUMMARY... Isolated severe thunderstorms with strong/gusty winds and hail will be possible across parts of the central Rockies and adjacent High Plains Sunday afternoon and evening. ...Synopsis... Cyclonic flow aloft will diminish over the northeastern U.S., as a low shifts northeastward across the Canadian Maritimes. In the West, a lead trough is forecast to shift east across the Intermountain West, eventually reaching the high Plains, ahead of a larger trough/low expected to move gradually onshore over the West Coast. In between the western and northeastern troughing, low-amplitude ridging will cross the central U.S. through the period. At the surface, a weak baroclinic zone will lie east to west across Missouri and Kansas, and then northwestward along the high Plains. As the upper system advances across the Rockies, a weak/elongated frontal low is forecast to gradually develop, centered over the northeastern Wyoming vicinity. ...Central High Plains vicinity... As the upper trough crosses the West, showers and thunderstorms are forecast to increase in coverage through the day across a broad portion of the Intermountain region. As increasing ascent begins reaching the high Plains during the afternoon, where low-level southeasterly flow is expected to maintain a slightly more moist low-level airmass, the more favorable instability will support an increase in storm coverage and intensity. The approach of the upper system will also bring a modest increase in flow aloft, likely supporting a progression of convection off the higher terrain and across the central high Plains -- possibly evolving into a semi-organized band or bands into the evening hours. This evolution will correspond with some potential for gusty/locally damaging winds, and possibly marginal hail through the evening hours. ..Goss/Elliott.. 09/08/2019 Read more