Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 AM CST Sat Nov 28 2020 Valid 301200Z - 011200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF FLORIDA/COASTAL GEORGIA INTO THE CAROLINAS AND MID-ATLANTIC... ...SUMMARY... Isolated strong to severe thunderstorms capable of producing damaging winds and perhaps a couple of tornadoes appear possible on Monday from parts of Florida and coastal Georgia into the Carolinas and Mid-Atlantic. ...Florida/Coastal Georgia into the Carolinas and Mid-Atlantic... A large-scale upper trough should evolve into a closed low over the Midwest/OH Valley and central Appalachians on Monday. A mid-level vorticity maximum embedded within this upper trough is forecast to move quickly northeastward from the central Appalachians into the Mid-Atlantic through Monday afternoon. A deep surface low should likewise develop northeastward in tandem with this vorticity maximum. A cold front trailing from this surface low will likely sweep eastward across much of the FL Peninsula and the East Coast through the day. A warm front extending northeastward from the surface low will probably make some northward progress across parts of the Mid-Atlantic through Monday afternoon as well. A line of low-topped showers/storms along or just ahead of the cold front should be ongoing at the start of the period from near the surface low in WV/western VA southward to northern FL. Although instability may remain modest across most of the warm sector ahead of this line, generally low to mid 60s surface dewpoints should be enough to support weak surface-based instability through the day. A very strong (50-60+ kt) south-southwesterly low-level jet should be present over the central/eastern Carolinas and southern VA Monday morning, and this feature is forecast to shift northward across the Mid-Atlantic through the day. Given the strength of the low-level flow and sufficient, albeit weak, forecast instability, strong to damaging winds may occur with storms that either persist along the cold front or develop ahead of it over the open warm sector. A couple tornadoes also appear possible, mainly across parts of eastern SC/NC/VA to the Delmarva Peninsula and perhaps NJ in associated with the low-level jet and potentially greater low-level moisture and instability. Even so, there is too much uncertainty regarding sufficient destabilization to include higher severe probabilities for now. Farther south, low-level convergence along the cold front and deep-layer shear are both forecast to be somewhat weaker across coastal GA and the FL Peninsula. Still, there may be isolated strong/gusty winds with any storms through Monday afternoon. ..Gleason.. 11/28/2020Read more
Day 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0136 AM CST Sat Nov 28 2020 Valid 291200Z - 301200Z ...Synopsis... An amplifying upper-level pattern over the CONUS will feature a deepening trough over the East with upper-level ridging over the West by the late weekend. While this pattern will feature weak mid-level winds across the Southwest, where conditions have been fairly dry, surface high pressure over the central CONUS will augment pressure gradient winds over the Plains and portions of southern California. This could lead to localized fire weather concerns. ...Southern California... Although upper-level ridging will continue to support weak winds aloft for Sunday, a reinforced surface high over the central Rockies and into the northern Great Basin will continue to foster offshore pressure-gradient winds for southern CA. Poor overnight RH recoveries are expected with RH values in the teens likely for Sunday afternoon. The LAX-DAG pressure gradient is forecast to be similar in magnitude as Saturday's, suggesting that elevated, to locally critical, fire weather conditions will be possible again for terrain-favored locations in the higher elevation of southern CA. This idea is supported by recent high-res ensemble guidance and deterministic model solutions. ...Central to Southern High Plains... Building surface high pressure over the northern High Plains in the wake of a cold front will help drive an increase in pressure-gradient winds through the day on Sunday. Strong northerly 850 mb flow within a cold advection regime over the central to southern Plains will help mix stronger winds down to the surface with gusts up to 30-40 mph possible. Some deterministic solutions and high-res ensemble members hint at the potential for RH reductions into the low 20s across western KS and the OK/TX Panhandles during the afternoon hours. However, confidence in this scenario is not high due to the potential for cold advection to limit RH reductions. Additionally, fuels across this region are only modestly receptive and portions of the OK/TX Panhandles may see prior precipitation on Saturday. As such, no highlights are introduced in this outlook, though trends in guidance and precipitation on Saturday will be monitored. ..Moore.. 11/28/2020 ...Please see www.spc.noaa.gov/fire for graphic product...Read more
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1250 AM CST Sat Nov 28 2020 Valid 291200Z - 301200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE LOWER MISSISSIPPI VALLEY...SOUTHEAST...AND CAROLINAS... ...SUMMARY... Isolated strong to severe thunderstorms may occur Sunday into Sunday night across parts of the lower Mississippi Valley, Southeast, and Carolinas. Damaging winds and perhaps a couple of tornadoes should be the main threats. ...Lower Mississippi Valley into the Southeast and Carolinas... A closed upper low centered over the southern Plains Sunday morning will move eastward through the day. This upper low should begin to merge with a positively tilted, northern-stream upper trough over the eastern states Sunday evening into early Monday morning. A weak surface low initially near the coast of southwestern LA is forecast to develop northeastward across parts of LA/MS/AL through the day while gradually deepening. Additional deepening of this surface low should occur from Sunday night through the end of the period as it continues developing northeastward along/near the spine of the southern/central Appalachians. A warm front attendant to the surface low will lift northward across parts of the Southeast and Carolinas, while a trailing cold front sweeps eastward across these regions through the period. Most guidance indicates that storms will be ongoing Sunday morning over the northern Gulf of Mexico near the LA Coast. Low-level warm advection should be the primary forcing mechanism for this activity, with the low-level jet forecast to shift northward across MS/AL through the day. Some concern remains regarding how much low-level moisture will be able to return inland given the potential for numerous to widespread storms over the northern Gulf of Mexico Sunday morning. If mid to upper 60s surface dewpoints can develop inland across parts of southern LA/MS/AL and the FL Panhandle in tandem with the deepening surface low and northward-advancing warm front, then only modest diurnal heating would be needed to support weak instability and surface-based storms. Strong effective bulk shear of 45-60 kt will easily support organized convection, with supercells possible along/ahead of the cold front. Isolated strong to damaging winds should be a concern given the strength of the low/mid-level flow and potential for storms to grow upscale into a low-topped line along the cold front by Sunday evening. Low-level shear also appears strong enough for updraft rotation, with a couple tornadoes possible across the warm sector with any semi-discrete storms. This isolated severe threat will probably continue across parts of GA into the Carolinas Sunday night and early Monday morning (end of the Day 2 period), as low-level moisture return occurs from the western Atlantic, and as a south-southwesterly jet rapidly strengthens over these areas. However, even though the low-level flow will likely be quite strong, instability is forecast to remain rather weak (generally less than 500 J/kg of MLCAPE). The northern extent of any meaningful damaging wind/tornado threat across the Southeast remains unclear, as there is uncertainty in how far north the mid 60s to upper surface dewpoints will advance. If confidence increases in a narrow corridor of greater instability developing across the warm sector on Sunday, then a Slight Risk for damaging winds and/or tornadoes may be included across some portion of these regions in a later outlook. ..Gleason.. 11/28/2020Read more
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1237 AM CST Sat Nov 28 2020 Valid 281200Z - 291200Z ...Synopsis... An upper-level closed low will continue to gradually shift eastward into the southern Plains through the day today, bringing widespread precipitation and cloud cover. To the north, a clipper low along the Canadian border will usher in a weak cold front across the northern High Plains. Breezy conditions behind this front could support brief fire weather concerns. Upper-level ridging over the West will mitigate most fire weather concerns for today. One exception will be the higher elevation of southern California where continued offshore flow may support a fire weather threat. ...Southern California... Although early morning surface observations show poor overnight RH recoveries across southern CA, winds are weaker compared to 24 hours ago with the exception of a few stations in the San Gabriel Mountains. This is largely due to gradual upper-level ridging over the West coast and diminishing winds throughout the column. Despite an approaching low-amplitude offshore disturbance, mid-level winds will continue to be weak through the day and limit the potential for widespread critical fire weather conditions. However, persistent offshore pressure-gradient winds will continue to support areas of elevated, to locally critical, fire weather conditions for the higher elevation of southern CA. The fire weather threat may be highest during the morning hours when the LAX-DAG pressure gradient is forecast to be the strongest before relaxing later in the day. ...Northern High Plains... Morning guidance continues to show the potential for elevated fire weather conditions this afternoon for western ND and eastern MT as winds increase behind a southeastward moving cold front. Fuels remain dry and/or dormant across this region and wind gusts upwards of 25-35 mph appear possible. However, uncertainty remains somewhat high regarding the degree of RH reductions with most guidance remaining above elevated RH thresholds. Additionally, the temporal window for elevated conditions appears limited to a couple of hours during the late afternoon. Due to these concerns no highlights are introduced, but conditions will continue to be monitored through the day. ..Moore.. 11/28/2020 ...Please see www.spc.noaa.gov/fire for graphic product...Read more
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1120 PM CST Fri Nov 27 2020 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms appear unlikely across the contiguous United States today. ...Discussion... As a trough within the fast northern-stream westerlies moves quickly across the Northeast today, an upper low south of the main belt of polar flow will move gradually eastward out of New Mexico and across the southern Plains. As this low advances, weak surface cyclogenesis is expected to begin later in the day, along a remnant baroclinic zone extending from south Texas eastward across the northern Gulf of Mexico/Gulf Coast region. Elsewhere, high pressure will prevail across most of the remainder of the country. At the start of the period Saturday morning, two main areas of convection will be ongoing -- one over the Southeast near the remnant front, in conjunction with an eastward-moving disturbance, and the second over Texas and the western Gulf. With time, the southeastern U.S. convection is forecast to move eastward/offshore, though a few showers and storms may linger over northern Florida through the afternoon near the surface front. Meanwhile, the Texas convection is expected to increase in coverage and spread eastward with time, eventually spreading into Louisiana and vicinity into the overnight hours as quasi-geostrophic forcing for ascent persists ahead of the advancing upper low. However, inland instability will remain weak and elevated, and post-frontal convection acting to reinforce the cool/stable boundary layer. The only exception to this overall expectation could evolve along the immediate coastal counties of the middle Texas coast. Here, proximity to the evolving frontal low could allow modest surface-based instability near the coast, along with a somewhat favorable wind profile. However, this appears to be a very low-probability scenario at this time, with the low expected to remain just offshore. Therefore, no risk areas will be added at this time. ..Goss/Moore.. 11/28/2020Read more
This is an automatic message WUUS52 KGSP 150312
BULLETIN – IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Greenville-Spartanburg SC
1112 PM EDT Sun Apr 14 2019
The National Weather Service in Greenville-Spartanburg has issued a
* Severe Thunderstorm Warning for…
Eastern Lincoln County in the Piedmont of North Carolina…
Southeastern Cleveland County in the Piedmont of North Carolina…
Gaston County in the Piedmont of North Carolina…
Northwestern York County in Upstate South Carolina…
Northeastern Cherokee County in Upstate South Carolina…
* Until midnight EDT.
* At 1112 PM EDT, severe thunderstorms were located along a line
extending from near Shelby to 19 miles west of Gastonia to 6 miles
east of Gaffney, moving east at 35 mph.
HAZARD…60 mph wind gusts.
IMPACT…Expect damage to trees and power lines.
* Locations impacted include…
Gastonia, Shelby, Kings Mountain, Mt Holly, Belmont, Cherryville,
Bessemer City, South Gastonia, Clover and Dallas.
Scattered trees and power lines will be blown down in the warned
area. Seek shelter inside an interior room.
These storms are also producing extremely heavy rainfall. Flooding of
drainage ditches and low lying areas may occur. Small streams will
rise rapidly. Do not drive through areas where water is flowing over
Please report damaging winds, hail, or flooding to the National
Weather Service Greenville-Spartanburg by calling toll free, 1, 800,
2 6 7, 8 1 0 1, or by posting on our Facebook page, or Tweet it using
hashtag nwsgsp. Your message should describe the event and the
specific location where it occurred.
A Tornado Watch remains in effect until 500 AM EDT for the Piedmont
of North Carolina…and Upstate South Carolina.
LAT…LON 3535 8097 3530 8100 3527 8102 3517 8100
3515 8101 3514 8105 3510 8103 3509 8106
3495 8165 3515 8157 3530 8163 3555 8106
3555 8096 3550 8096 3549 8095 3545 8094
3543 8096 3539 8095 3537 8099 3536 8092
TIME…MOT…LOC 0312Z 248DEG 32KT 3526 8153 3518 8150 3504 8155
HAIL…<.75IN WIND...60MPH $$ HG