SPC Jan 19, 2018 1630 UTC Day 1 Convective Outlook

 For best viewing experience, please enable browser JavaScript/Active Scripting.

Jan 19, 2018 1630 UTC Day 1 Convective Outlook
Updated: Fri Jan 19 16:13:39 UTC 2018 (Print Version | 20180119 1630Z Day 1 shapefile | 20180119 1630Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
 Forecast Discussion
 SPC AC 191613 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1013 AM CST Fri Jan 19 2018 Valid 191630Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Isolated thunderstorms will be possible along the Texas and central California coasts. ...Synopsis... A weak midlevel trough will continue to drift eastward near the northwest Gulf coast. Though the weakly unstable warm sector and the majority of the deep convection remains offshore, weak midlevel buoyancy does extend inland over the TX coastal plain per the 12z sounding at Corpus Christi. Low-level warm advection should maintain some weak midlevel convection, and the potential for isolated lightning strikes, through early afternoon. Otherwise, an upstream shortwave trough is progressing east-southeastward toward CA. Low-topped convection accompanies the midlevel thermal trough per satellite imagery, and a few lightning flashes have been detected off the central CA coast as of 16z. Weak surface-based buoyancy will reach the immediate central CA coast later today in conjunction with the steeper low-midlevel lapse rates, though thunderstorm coverage should remain isolated, at best. ..Thompson/Gleason.. 01/19/2018 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
Top/Latest Day 2 Outlook/Today’s Outlooks/Forecast Products/Home

http://www.spc.noaa.gov/products/outlook/day1otlk_1630.html SPC Convective Outlooks


SPC Jan 19, 2018 1300 UTC Day 1 Convective Outlook

 SPC AC 191249 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0649 AM CST Fri Jan 19 2018 Valid 191300Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... A few thunderstorms are possible near portions of the Texas coast. Severe storms are not expected today. ...Synopsis... In mid/upper levels, a low-amplitude pattern exists across the northern 1/2-1/3 of the country, downstream from a high-amplitude, positively tilted trough now located just offshore from the West Coast. That trough is forecast to move eastward through the period, reaching southern ID, NV, southern CA, and offshore central/northern Baja by 12Z. Meanwhile, a considerably weaker southern-stream trough -- now evident in moisture-channel imagery from AR across south TX to Sinaloa (MX) -- is expected to move eastward and weaken gradually. By the end of the period, this trough should be located from northern AL to deep south TX and northeastern MX. At the surface, stable/low-theta-e conditions will prevail over most of the nation in the wake of recent polar frontal passages. However, sufficient low-level moisture, lift and instability above the surface will exist to support a thunderstorm risk near the TX coast as discussed below. A north-south elongated, frontal-wave cyclone was analyzed at 11Z off the lower TX coast with quasistationary front southward parallel to the northeastern MX coast and a warm front east-southeastward across the central Gulf. A second front, representing a marine-flux-induced thermal gradient in cooler ambient air, arched from the low across the outer shelf waters of the TX coast. The low should become more diffuse this evening and overnight as the mid/upper wave moves past, while the marine/warm-frontal zones slowly merge and shift northward. ...TX coast... A plume of convection, with isolated to widely scattered embedded thunderstorms, will continue through much of today before diminishing tonight as related lift weakens. Until then, this activity will be supported by a combination of: * Elevated moisture return in an immature but still sufficient source-trajectory modification regime; * Contributions to large-scale ascent from weak DCVA (ahead of the southern-stream trough) and low-level warm advection; * Frontogenetic forcing, primarily over water. The 12Z CRP sounding yielded about 500 J/kg elevated MUCAPE, which should be near the maximum amount likely to occur over land. Buoyancy should be larger and deeper over water and near the low where low/middle-level lapse rates are greatest. Although the bulk of thunderstorms will remain over the Gulf, sporadic/isolated lightning is possible over the coast and just inland. ..Edwards/Broyles.. 01/19/2018 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z

http://www.spc.noaa.gov/products/outlook/day1otlk_1300.html SPC Convective Outlooks


SPC Jan 19, 2018 Day 4-8 Severe Weather Outlook

USA.gov is the U.S. Government's official Web portal to all Federal, state and local government Web resources and services.
Day 4-8 Severe Weather Outlook Issued on Jan 19, 2018
Updated: Fri Jan 19 09:03:02 UTC 2018

 For best viewing experience, please enable browser JavaScript/Active Scripting.

D4Mon, Jan 22, 2018 – Tue, Jan 23, 2018D7Thu, Jan 25, 2018 – Fri, Jan 26, 2018
D5Tue, Jan 23, 2018 – Wed, Jan 24, 2018D8Fri, Jan 26, 2018 – Sat, Jan 27, 2018
D6Wed, Jan 24, 2018 – Thu, Jan 25, 2018(All days are valid from 12 UTC – 12 UTC the following day)
Note: A severe weather area depicted in the Day 4-8 period indicates 15%, 30% or higher probability for severe thunderstorms within 25 miles of any point.
PREDICTABILITY TOO LOW is used to indicate severe storms may be possible based on some model scenarios. However, the location or occurrence of severe storms are in doubt due to: 1) large differences in the deterministic model solutions, 2) large spread in the ensemble guidance, and/or 3) minimal run-to-run continuity.
POTENTIAL TOO LOW means the threat for a regional area of organized severe storms appears unlikely (i.e., less than 15%) for the forecast day.
 Forecast Discussion
 ZCZC SPCSWOD48 ALL ACUS48 KWNS 190901 SPC AC 190901 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0301 AM CST Fri Jan 19 2018 Valid 221200Z - 271200Z ...DISCUSSION... Some differences exists within the medium-range guidance regarding the progression of the mature system likely centered over the central Plains at the beginning of the period (12Z Monday). However, the overall progression is similar with the system moving off the Northeast coast late Tuesday or early Wednesday. Some thunderstorms are possible Monday as the front associated with this system interacts with the more moist and unstable air along the Gulf Coast. Some severe cannot be ruled out, particularly along the central Gulf Coast, but limited instability should keep the overall severe threat low. Models are showing relatively good model-to-model and run-to-run consistency regarding upper ridging across the Plains on Wednesday and Thursday before another more substantial shortwave trough moves into the region on Friday. Even so, uncertainty regarding moisture return and resulting instability ahead of this system as well as typical uncertainties at this range (i.e. Day 7) lead to low forecast confidence. ..Mosier.. 01/19/2018 CLICK TO GET WUUS48 PTSD48 PRODUCT 

http://www.spc.noaa.gov/products/exper/day4-8/ SPC Convective Outlooks


SPC Jan 19, 2018 0830 UTC Day 3 Severe Thunderstorm Outlook

USA.gov is the U.S. Government's official Web portal to all Federal, state and local government Web resources and services.

 For best viewing experience, please enable browser JavaScript/Active Scripting.

Jan 19, 2018 0830 UTC Day 3 Severe Thunderstorm Outlook
Updated: Fri Jan 19 07:35:22 UTC 2018 (Print Version | 20180119 0830Z Day 3 shapefile | 20180119 0830Z Day 3 KML)
Probabilistic to Categorical Outlook Conversion Table
 Forecast Discussion
 SPC AC 190735 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0135 AM CST Fri Jan 19 2018 Valid 211200Z - 221200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF EAST TX...FAR SOUTHEAST OK AND WESTERN AR... ...SUMMARY... Isolated severe thunderstorms are possible Sunday afternoon and evening from east Texas northeastward into western Arkansas. ...Synopsis... Shortwave trough over the Four Corners region at the beginning of the period is expected to progress northeastward into the central Plains while deepening and maturing. Southwesterly winds aloft preceding the system will strengthen while overspreading the southern/central Plains and lower/mid MS Valley. Surface reflection of this system will move quickly northeastward from the TX Panhandle into the lower MO Valley. Moisture return ahead of this system will likely result in enough instability to support thunderstorms, include the potential for a few severe storms (discussed in more detail below). Farther northwest, a progressive shortwave trough will move through the Pacific Northwest during the afternoon/evening. A few lightning strikes will be possible across the region, particularly after the initial frontal band as temperatures aloft cool and cellular convection persists. ...East TX...Far southeast OK...Western AR... Moisture return is expected to result in dewpoints in the upper 50s to low 60s from the lower TX coast northward through the Ark-La-Tex. Daytime heating will be limited by considerable cloudiness, tempering the development of much surface-based instability. Current guidance suggests SBCAPE values will remain below 500 J/kg. Additionally, expected progression of the upper system will result in a displacement between the strongest forcing for ascent (across eastern KS and MO) and the best low-level moisture/instability. Even so, a line of showers and thunderstorms is expected to develop during the afternoon as the Pacific front/dryline associated with the system encounters the marginally unstable environment across east/northeast TX. Continued thunderstorm development is possible farther north through western AR during the evening. Strong wind fields will favor fast-moving storms and the potential for a few strong wind gusts, particularly during the late afternoon and evening from east TX into western AR where the greatest potential for surface-based convection exists. Despite strong forcing for ascent, northern extent of the severe threat will be limited by meager instability. Farther south, warm temperatures aloft will likely keep afternoon and evening convection shallow. ..Mosier.. 01/19/2018 CLICK TO GET WUUS03 PTSDY3 PRODUCT NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0830Z
Top/Latest Day 1 Outlook/Today’s Outlooks/Forecast Products/Home

http://www.spc.noaa.gov/products/outlook/day3otlk_0830.html SPC Convective Outlooks


SPC Jan 19, 2018 0700 UTC Day 2 Convective Outlook

 For best viewing experience, please enable browser JavaScript/Active Scripting.

Jan 19, 2018 0700 UTC Day 2 Convective Outlook
Updated: Fri Jan 19 05:38:59 UTC 2018 (Print Version | 20180119 0700Z Day 2 shapefile | 20180119 0700Z Day 2 KML)
Probabilistic to Categorical Outlook Conversion Table
 Forecast Discussion
 SPC AC 190538 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1138 PM CST Thu Jan 18 2018 Valid 201200Z - 211200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... The potential for thunderstorms appears low across the United States Saturday. ...Synopsis... A strong shortwave trough is expected to migrate from the western Great Basin east-southeastward through the Four Corners on Saturday. A lightning strike or two is possible across the Four Corners region as mid-level temperatures cool in response to the progression of the shortwave trough. Strong southwesterly flow aloft accompanying the system will spread across the Southwest states early in the period, extending through the southern High Plains into the central Plains/middle MO valley by the end of the period. This increasing southwesterly flow aloft will favor lee cyclogenesis across the central High Plains, contributing to strengthening southwesterly surface winds and continued airmass modification across the southern and central Plains. By Saturday afternoon, mid 50s dewpoints will likely exist from the TX Coastal Plain northward/northeastward into the Ark-La-Tex. However, the lack of large-scale forcing for ascent and warm temperatures aloft will preclude deep convection and lightning production. ..Mosier.. 01/19/2018 CLICK TO GET WUUS02 PTSDY2 PRODUCT NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z
Top/Latest Day 1 Outlook/Today’s Outlooks/Forecast Products/Home

http://www.spc.noaa.gov/products/outlook/day2otlk_0700.html SPC Convective Outlooks


SPC Jan 19, 2018 0600 UTC Day 1 Convective Outlook

 For best viewing experience, please enable browser JavaScript/Active Scripting.

Jan 19, 2018 0600 UTC Day 1 Convective Outlook
Click to see valid 1Z – 12Z Day 1 Convective Outlook
Updated: Fri Jan 19 05:24:27 UTC 2018 (Print Version | 20180119 1200Z Day 1 shapefile | 20180119 1200Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
 Forecast Discussion
 SPC AC 190524 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1124 PM CST Thu Jan 18 2018 Valid 191200Z - 201200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms will not occur in the United States today. ...TX coast... A mid-level low/trough will slowly progress eastward across south-central and into southeast TX during the period. A maritime front located over the shelf waters will move little. However, increasing large-scale ascent and moistening above a shallow stable layer near the surface, will favor shower development and the risk for a few thunderstorms. Models suggest the potential for thunderstorms will diminish during the evening. Elsewhere, stable conditions will prove hostile to convective development. ..Smith/Leitman.. 01/19/2018 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z
Top/Latest Day 2 Outlook/Today’s Outlooks/Forecast Products/Home

http://www.spc.noaa.gov/products/outlook/day1otlk_1200.html SPC Convective Outlooks


SPC Jan 19, 2018 0100 UTC Day 1 Convective Outlook

 For best viewing experience, please enable browser JavaScript/Active Scripting.

Jan 19, 2018 0100 UTC Day 1 Convective Outlook
Updated: Fri Jan 19 00:49:11 UTC 2018 (Print Version | 20180119 0100Z Day 1 shapefile | 20180119 0100Z Day 1 KML)
Probabilistic to Categorical Outlook Conversion Table
 Forecast Discussion
 SPC AC 190049 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0649 PM CST Thu Jan 18 2018 Valid 190100Z - 191200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms will not occur over the contiguous United States through early Friday morning. ...Synopsis... A belt of strong mid-level flow will extend from the CA coast northeast to the southern portion of the Canadian prairie provinces and east to the Northeast. A large-scale trough will be maintained off the West Coast and a weak mid-level low/trough will meander over TX. In the low levels, surface high pressure will reside over the Gulf Coast states. A few thunderstorms are possible with weak convection in a scant-buoyancy regime along the northern half of the West Coast and perhaps later tonight over Deep South TX. ..Smith.. 01/19/2018 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0600Z
Top/Latest Day 2 Outlook/Today’s Outlooks/Forecast Products/Home

http://www.spc.noaa.gov/products/outlook/day1otlk_0100.html SPC Convective Outlooks