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National Severe Weather Outlook for the next week

Here you'll find all available severe weather outlooks on one page.

Overview of the threat for the next few days

Outlook for Thursday, May 28

Outlook Summary

Within a very extensive swath of marginal severe-storm potential, two areas appear to have the most-concentrated hail/wind threats today: parts of Mississippi/Alabama and southern Tennessee, as well as southwest Texas near the Rio Grande.

Outlook Images

Detailed Outlook

SPC AC 281254

Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0754 AM CDT Thu May 28 2020

Valid 281300Z - 291200Z

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF MISSISSIPPI/ALABAMA AND SOUTHERN TENNESSEE…AS WELL AS SOUTHWEST TEXAS NEAR THE RIO GRANDE

### SUMMARY

Within a very extensive swath of marginal severe-storm potential, two areas appear to have the most-concentrated hail/wind threats today: parts of Mississippi/Alabama and southern Tennessee, as well as southwest Texas near the Rio Grande.

Synopsis

The upper-air pattern from the CONUS westward across the northeastern Pacific will remain one characterized by split flow and cutoff lows, albeit with a deamplifying trend beginning in this period. The Ozarks-area cyclone and attached trough are forecast to devolve into a weakening, open-wave perturbation. By 12Z tomorrow, the resulting shortwave trough should extend from the lower Ohio Valley, northern MS, northern LA and southeast TX, somewhat in phase with a convectively induced/enhanced vorticity maximum over northeastern MX. This will occur as a northern-stream trough – evident in moisture-channel imagery from the MB-ON border to the Dakotas – pivots to the James Bay region, Lake Superior and the upper Mississippi Valley. Strong synoptic-scale ridging will shift eastward across the AZ, the Great Basin and northern Rockies.

At the surface, a low was analyzed over east-central IA, with diffuse, quasistationary front across eastern MO, central AR, and southeast/south-central TX. A secondary cold front was organizing from the low southwestward across southwestern OK to northwest TX and southeastern NM. The secondary front will overtake the northward-retreating leading boundary over south TX this afternoon and evening.

An extensive area of at least marginal, localized severe potential is evident from the interior Mid-Atlantic to the Gulf States and southeastern NM, with a northward break, then near parts of the central Rockies in low-level upslope flow. This discussion will focus on two relative concentrations of severe threat within the broader swath.

TX near Rio Grande

Widely scattered thunderstorms are expected to develop today over the western and northern parts of the outlook area. Thunderstorms regionally will be forced by a combination of lift from surface heating, the southward-moving baroclinic zone, and orographic forcing over the Big Bend region and northern Coahuila. Additional convection is possible this evening farther east as the frontal zone impinges on richer inflow-layer moisture. Large hail and severe gusts will be the main concerns.

Height rises are expected as the Ozarks cyclone/trough weaken and move away from the area. Nonetheless, associated northwesterly flow aloft and strong directional shear will persist, despite weak low-level winds. This will contribute to 30-40-kt effective-shear magnitudes, though the lack of more robust low-level flow will limit hodograph size. Steep midlevel lapse rates, along with some moisture return through an air mass affected by prior days' convective complexes, will combine to yield MLCAPE in the 2000-3000 J/kg range across much of this region. More-robust moisture return is probable this evening over south-central TX and the lower Rio Grande Valley, which will be available to any convection that can develop anew along the combined frontal zone, or evolve upscale from diurnally initiated convection from Coahuila. That contingency appears increasingly probable based on more-recent guidance and the observational trends in the lower Rio Grande Valley, so the outlook has been expanded on the east side.

MS/AL

Widely scattered to scattered thunderstorms should develop this afternoon and move northeastward across this region, offering sporadic strong-severe gusts and large hail. Activity should form atop a weakly capped, strongly heated and increasingly moist boundary layer. Peak preconvective MLCAPE may reach 1000-1500 J/kg, despite modest midlevel lapse rates, with a well-mixed subcloud layer supporting maintenance of gusts/hail to the surface. The outlook area generally represents a relative max in expected convective coverage within the broader moist plume occupying the low levels to the southeast of the ejecting cyclone/trough, along with associated modest increase in deep shear. A cyclonically curved belt of relatively strong mid/upper winds will contribute to 30-40-kt effective-shear magnitudes and favorable upper-level ventilating flow, in support of convective organization. Weak low-level winds and lack of stronger buoyancy will be limiting factors.

..Edwards/Smith.. 05/28/2020

CLICK TO GET WUUS01 PTSDY1 PRODUCT

NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z

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Outlook for Friday, May 29

Outlook Summary

Severe thunderstorms are possible across portions of the northern Mid-Atlantic and Northeast States Friday afternoon through Friday evening.

Outlook Images

Detailed Outlook

SPC AC 280545

Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1245 AM CDT Thu May 28 2020

Valid 291200Z - 301200Z

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE NORTHERN MID-ATLANTIC INTO THE NORTHEAST STATES

### SUMMARY

Severe thunderstorms are possible across portions of the northern Mid-Atlantic and Northeast States Friday afternoon through Friday evening.

OH Valley into the Northern Mid-Atlantic and Northeast

A shortwave trough and attendant vorticity maximum are forecast to move from the middle OH Valley northeastward into western portions of the Northeast states on Friday. Another shortwave will move through the Upper Great Lakes, in close proximity to the lead wave. By early Saturday morning, these two shortwaves will have merged into one coherent shortwave extending from southern Quebec southward into the northern Mid-Atlantic.

Dewpoints in the upper 60s (possibly low 70s) are anticipated from the Mid-Atlantic northward into upstate NY, with slightly lower values expected across the middle and upper OH Valley. Given this low-level moisture, the air mass will destabilize under modest heating ahead of the approaching shortwave troughs and associated cold front. Lead shortwave trough is expected to induce convective initiation throughout the warm sector over the Northeast and northern Mid-Atlantic, while the second shortwave trough and attendant cold front aid in convective development over the middle and upper OH Valley.

A predominately multicell mode with numerous line segments is anticipated. Vertical shear is strong enough to support storm organization, resulting in the potential for damaging wind gusts with the more robust line segments. Some isolated hail is also possible, particularly with any more discrete storms. The tornado threat will depend largely on direction of the surface winds and strength of the low-level flow. A more southerly surface-wind direction combined with stronger low-level flow will contribute to greater low-level shear and higher tornado potential. Highest likelihood for these conditions currently exists from central VA northward into upstate NY. However, confidence is occurrence is currently low, since most of the guidance either lacks southerly surface winds or enhanced low-level flow. Consequently, only marginal tornado probabilities will be included with this outlook.

Pacific Northwest

A compact upper cyclone is forecast to move northeasterly toward the central CA coast from Friday evening/overnight into Saturday morning. The progression of this system will result in mid-level moisture advection into the Pacific Northwest, beginning on Friday morning. By Friday afternoon, the combination of this mid-level moisture and deep boundary-layer mixing could support moderate instability across portions of OR. Large-scale forcing for ascent will be weak, but convergence and orographic effects on the western edge of a deepening surface low could result in isolated thunderstorms. Recent guidance has trended towards later storm initiation with coverage now expected to be too low to merit any severe probabilities.

..Mosier.. 05/28/2020

CLICK TO GET WUUS02 PTSDY2 PRODUCT

NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 1730Z

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Outlook for Saturday, May 30

Outlook Summary

Isolated severe thunderstorms are possible from the interior Pacific Northwest eastward/southeastward across the northern and central High Plains on Saturday.

Outlook Images

Detailed Outlook

SPC AC 280712

Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0212 AM CDT Thu May 28 2020

Valid 301200Z - 311200Z

THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE INTERIOR PACIFIC NORTHWEST EASTWARD/SOUTHEASTWARD ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS

### SUMMARY

Isolated severe thunderstorms are possible from the interior Pacific Northwest eastward/southeastward across the northern and central High Plains on Saturday.

East Coast into the Southeast

At the beginning of the period, a cold front is forecast to extend from a surface low over far eastern Quebec southward to Delmarva then back southwestward to the central Gulf Coast then arc westward/northwestward to a low over the central High Plains. This front represents the leading edge of a dry and stable continental air mass that will build southeastward from the northern Plains through the MS Valley into the Southeast. Showers and thunderstorms are possible along and ahead of this front, with the highest coverage expected from the Carolinas into the FL Panhandle. However, weak vertical shear should preclude storm organization and minimize any severe potential across much of the region. The only exception is across eastern ME, where stronger vertical shear could support more organized storms and higher severe potential. However, uncertainty regarding frontal position and storm coverage precludes including any severe probabilities with this outlook.

Pacific Northwest into the High Plains

Farther west, compact cyclone over the northern CA coast early Saturday is expected to devolve into an open shortwave trough as it moves quickly northeastward through the interior Pacific Northwest and northern Rockies. Surface low attendant to this upper system is expected to deepen in the lee of the Cascades before moving into southern British Columbia early Sunday morning. Southeasterly surface winds will strengthen across the northern High Plains, contributing to aggressive northwestward low-level moisture advection. By late Saturday afternoon, mid 50s dewpoints could be in place across much of central and eastern MT. Dewpoints closer to 60 deg F could develop where less boundary-layer mixing takes place near the surface low over eastern WA.

All of these factors contribute to a fairly anomalous pattern for this part of the country. Warm temperatures aloft will keep the area capped until the late afternoon/early evening. Therefore, forcing for ascent near the surface low and shortwave trough is expected to result in thunderstorms. Given the environment, some of these storms may be severe. While guidance has been relatively consistent regarding this scenario, combination of factors needed to produce this environment (i.e. near 60s dewpoints, surface low location, late afternoon/early evening shortwave timing) are still uncertain enough at this forecast range to only introduce 5% severe probabilities.

Aforementioned moisture advection combined with a sharpening lee trough will likely result in scattered convective initiation along the northern and central High Plains. The deeply mixing boundary layer and veering wind profiles could contribute to a few stronger storms capable of strong wind gusts and hail.

..Mosier.. 05/28/2020

CLICK TO GET WUUS03 PTSDY3 PRODUCT

NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z

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Outlook for Sunday, May 31

Outlook Images

Detailed Outlook

ZCZC SPCSWOD48 ALL ACUS48 KWNS 280834 SPC AC 280834

Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0334 AM CDT Thu May 28 2020

Valid 311200Z - 051200Z

DISCUSSION

Upper pattern is forecast to amplify on D4/Sunday and D5/Monday as the central CONUS ridging builds and the two flanking upper troughs deepen. Presence of this upper ridging will push the stronger westerly flow aloft northward into south-central Canada. Some stronger flow aloft is also possible across the Northeast with an shortwave troughs that crest the ridge and then move southeastward into that region. Even if that occurs, it will be displaced eastward of the better low-level moisture and instability, which is forecast to be over the northern/central Plains into the Upper/Middle MS Valley on early next week. Background upper ridging suggests a widespread severe-weather event is unlikely, but the strong instability over these regions will likely support a mesoscale-driven severe risk.

..Mosier.. 05/28/2020

CLICK TO GET WUUS48 PTSD48 PRODUCT

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Outlook for Monday, June 1

Outlook Images

Detailed Outlook

ZCZC SPCSWOD48 ALL ACUS48 KWNS 280834 SPC AC 280834

Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0334 AM CDT Thu May 28 2020

Valid 311200Z - 051200Z

DISCUSSION

Upper pattern is forecast to amplify on D4/Sunday and D5/Monday as the central CONUS ridging builds and the two flanking upper troughs deepen. Presence of this upper ridging will push the stronger westerly flow aloft northward into south-central Canada. Some stronger flow aloft is also possible across the Northeast with an shortwave troughs that crest the ridge and then move southeastward into that region. Even if that occurs, it will be displaced eastward of the better low-level moisture and instability, which is forecast to be over the northern/central Plains into the Upper/Middle MS Valley on early next week. Background upper ridging suggests a widespread severe-weather event is unlikely, but the strong instability over these regions will likely support a mesoscale-driven severe risk.

..Mosier.. 05/28/2020

CLICK TO GET WUUS48 PTSD48 PRODUCT

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Outlook for Tuesday, June 2

Outlook Images

Detailed Outlook

ZCZC SPCSWOD48 ALL ACUS48 KWNS 280834 SPC AC 280834

Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0334 AM CDT Thu May 28 2020

Valid 311200Z - 051200Z

DISCUSSION

Upper pattern is forecast to amplify on D4/Sunday and D5/Monday as the central CONUS ridging builds and the two flanking upper troughs deepen. Presence of this upper ridging will push the stronger westerly flow aloft northward into south-central Canada. Some stronger flow aloft is also possible across the Northeast with an shortwave troughs that crest the ridge and then move southeastward into that region. Even if that occurs, it will be displaced eastward of the better low-level moisture and instability, which is forecast to be over the northern/central Plains into the Upper/Middle MS Valley on early next week. Background upper ridging suggests a widespread severe-weather event is unlikely, but the strong instability over these regions will likely support a mesoscale-driven severe risk.

..Mosier.. 05/28/2020

CLICK TO GET WUUS48 PTSD48 PRODUCT

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Outlook for Wednesday, June 3

Outlook Images

Detailed Outlook

ZCZC SPCSWOD48 ALL ACUS48 KWNS 280834 SPC AC 280834

Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0334 AM CDT Thu May 28 2020

Valid 311200Z - 051200Z

DISCUSSION

Upper pattern is forecast to amplify on D4/Sunday and D5/Monday as the central CONUS ridging builds and the two flanking upper troughs deepen. Presence of this upper ridging will push the stronger westerly flow aloft northward into south-central Canada. Some stronger flow aloft is also possible across the Northeast with an shortwave troughs that crest the ridge and then move southeastward into that region. Even if that occurs, it will be displaced eastward of the better low-level moisture and instability, which is forecast to be over the northern/central Plains into the Upper/Middle MS Valley on early next week. Background upper ridging suggests a widespread severe-weather event is unlikely, but the strong instability over these regions will likely support a mesoscale-driven severe risk.

..Mosier.. 05/28/2020

CLICK TO GET WUUS48 PTSD48 PRODUCT

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Outlook for Thursday, June 4

Outlook Images

Detailed Outlook

ZCZC SPCSWOD48 ALL ACUS48 KWNS 280834 SPC AC 280834

Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0334 AM CDT Thu May 28 2020

Valid 311200Z - 051200Z

DISCUSSION

Upper pattern is forecast to amplify on D4/Sunday and D5/Monday as the central CONUS ridging builds and the two flanking upper troughs deepen. Presence of this upper ridging will push the stronger westerly flow aloft northward into south-central Canada. Some stronger flow aloft is also possible across the Northeast with an shortwave troughs that crest the ridge and then move southeastward into that region. Even if that occurs, it will be displaced eastward of the better low-level moisture and instability, which is forecast to be over the northern/central Plains into the Upper/Middle MS Valley on early next week. Background upper ridging suggests a widespread severe-weather event is unlikely, but the strong instability over these regions will likely support a mesoscale-driven severe risk.

..Mosier.. 05/28/2020

CLICK TO GET WUUS48 PTSD48 PRODUCT

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National Risk Overview

Thursday, May 28

TORNADO: 2%

HAIL: 15%

WIND: 15%

Friday, May 29

TORNADO: 2%

HAIL: 5%

WIND: 15%

Saturday, May 30

ANY SEVERE: 5%

Sunday, May 31

ANY SEVERE: low / uncertain

Monday, June 1

ANY SEVERE: low / uncertain

Tuesday, June 2

ANY SEVERE: low / uncertain

Wednesday, June 3

ANY SEVERE: low / uncertain

Thursday, June 4

ANY SEVERE: low / uncertain

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