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Current Mesoscale Discussions
SPC - No watches are valid as of Mon Jan 25 22:51:03 UTC 2021
No watches are valid as of Mon Jan 25 22:51:03 UTC 2021.
SPC MD 33
MD 0033 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR NORTHERN/CENTRAL MISSISSIPPI...WESTERN/MIDDLE TENNESSEE...NORTHWEST ALABAMA
Mesoscale Discussion 0033 NWS Storm Prediction Center Norman OK 0449 PM CST Mon Jan 25 2021 Areas affected...Northern/Central Mississippi...Western/Middle Tennessee...Northwest Alabama Concerning...Severe potential...Watch possible Valid 252249Z - 260015Z Probability of Watch Issuance...60 percent SUMMARY...Scattered strong thunderstorms are expected across the Mid-South into Middle TN this evening. Some risk for tornadoes may necessitate a watch in the next couple of hours. DISCUSSION...Strong mid-level short-wave trough is ejecting across the central Plains this evening. The more appreciable height falls will spread across the Mid-MS into the OH Valley region. Along the southern fringe of this stronger large-scale forcing, robust convection has recently developed across portions of western TN where surface dew points have risen into the mid 60s with surface temperatures in the lower 70s. This activity should spread east-northeast along a corridor that is destabilizing just south of a well-defined warm front. Ample shear/buoyancy exist for supercells (possibly tornadic supercell ongoing over Fayette County TN) and there is increasing concern/confidence that other organized longer-lived storms may develop. Farther south along the Pacific front, showers are gradually deepening from northwest MS into northeast LA. Some lightning is noted with the stronger updrafts but activity has struggled to organize. It's not entirely clear how many organized supercells can/will develop along this zone, but shear/buoyancy do favor some tornado threat. Tornado watch may be warranted for this activity in the next couple of hours. ..Darrow/Thompson.. 01/25/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OHX...BMX...HUN...MEG...JAN... LAT...LON 33159055 35478893 35888710 35008651 33568819 32718919 33159055Read more
MD 0000 CONCERNING
SPC Jan 25, 2021 2000 UTC Day 1 Convective Outlook
SPC 2000Z Day 1 OutlookDay 1 Convective Outlook NWS Storm Prediction Center Norman OK 0156 PM CST Mon Jan 25 2021 Valid 252000Z - 261200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING ACROSS PARTS OF NORTHEASTERN MISSISSIPPI AND NORTHWESTERN ALABAMA INTO MIDDLE TENNESSEE... ...SUMMARY... A few severe thunderstorms are possible this evening within a corridor across northeastern Mississippi and northwestern Alabama into middle Tennessee. This includes a risk for potentially damaging wind gusts and perhaps a couple of tornadoes. ...20Z Outlook Update... Adjustments to the categorical and probabilistic outlook lines were made to account for the progression of synoptic and sub-synoptic features, and latest trends concerning ongoing destabilization. ...Mid South vicinity... Low-level moisture return is ongoing on southerly return flow across the lower Mississippi into Tennessee Valleys. This appears to be contributing to modest boundary-layer destabilization (including CAPE up to 500-1000 J/kg), which is expected to continue developing northeastward as an initial short wave impulse, which has emerged from the Southwest, progresses east-northeast of the central Great Plains late this afternoon and evening. As the associated frontal wave migrates into the lower Ohio Valley, there appears a window of opportunity for vigorous convective development focused along/just ahead of the trailing surface trough across Tennessee into Mississippi. This may coincide with a 40-50 kt southerly 850 mb jet axis, along which enlarged low-level hodographs may become support of supercells structures accompanied by the risk for damaging wind gusts and/or a couple of tornadoes. With the influence of the mid/upper forcing on the warm sector expected to be glancing/short-lived, it appears this risk will be maximized this evening, but at least some severe weather potential may linger as remnant convection spreads eastward/southeastward overnight. ...Arizona... A corridor of modest boundary-layer destabilization is ongoing across the international border into southern Arizona, ahead of the vigorous short wave impulse now turning inland of the southern California coast. Coincident with strengthen of west-southwesterly flow to 30-40+ kt in the 850-700 mb layer, the environment may become conducive for isolated thunderstorm development with the potential to produce strong surface gusts approaching or briefly exceeding severe limits. ..Kerr.. 01/25/2021 .PREV DISCUSSION... /ISSUED 1025 AM CST Mon Jan 25 2021/ ...TN Valley today... A progressive shortwave trough continues to move across the central Plains today, with an associated 100kt+ mid level jet extending from north TX into MO. The primary surface low for this system is over northwest AR, with a warm front extending eastward along the KY/TN border. Strong low-level wind fields are present across the warm sector, with sufficient CAPE to pose a marginal risk of a few fast-moving storms capable of gusty winds. However, model guidance continues to suggest that slight veering in the low-level winds will weaken convergence/forcing and limit coverage of deep convection. ...MS/AL/TN this evening and tonight... After dark, a few thunderstorms are expected to form over parts of MS/Al and middle TN along/ahead of the advancing cold front. Low-level and deep-layer vertical shear profiles in this area will be favorable for storm organization/rotation, and will maintain the marginal probabilities for isolated tornadoes or damaging wind gusts. The primary forecast concern in this region will be storm coverage, and poor thermodynamics in the lowest 3-4 km suggest that updrafts may struggle to intensify. This area will continue to be evaluated in later outlooks.Read more
SPC Day 2 Fire Weather Outlook
SPC Day 2 Fire Weather OutlookDay 2 Fire Weather Outlook NWS Storm Prediction Center Norman OK 1256 PM CST Mon Jan 25 2021 Valid 261200Z - 271200Z ...NO CRITICAL AREAS... No changes to the ongoing forecast. ..Wendt.. 01/25/2021 .PREV DISCUSSION... /ISSUED 0136 AM CST Mon Jan 25 2021/ ...Synopsis... Large scale troughing is forecast to continue across the West as high pressure develops across the northern and central US. With an abundance of cool air moving in from the north and widespread precipitation expected, overall fire weather potential is low across much of the CONUS. ...Texas Trans Pecos... Dry downslope winds of 15-20 mph and humidity values of 15-25% will likely support at least locally elevated to near critical fire weather conditions across a small portion of the Rio Grande Valley toward the Texas Big Bend. While fuels remain receptive to fire spread given the lack of recent precipitation, fuel coverage remains sparse across this area. In addition, the temporal window for favorable fire weather conditions is expected to be rather narrow, with the fast-moving cold front bringing cooler temperatures and higher humidity into the area by late afternoon. This suggests any fire weather threats that do develop will likely remain local in nature, negating the need for an elevated delineation at this time. ...Please see www.spc.noaa.gov/fire for graphic product...Read more