Storm Prediction Center
No watches are valid as of Fri Apr 16 06:48:02 UTC 2021.
No Mesoscale Discussions are in effect as of Fri Apr 16 06:48:02 UTC 2021.
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1253 AM CDT Fri Apr 16 2021 Valid 161200Z - 171200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM EASTERN TEXAS ALONG THE GULF COAST TO NORTHERN FLORIDA AND IN PORTIONS SOUTH TEXAS.... ...SUMMARY... Isolated strong to severe storms capable of hail and gusty winds are possible across parts of eastern Texas along the Gulf Coast and into north Florida today. An isolated strong to severe storm capable of large hail may be possible along the Rio Grande in the South Texas late in the period. ...Synopsis... A mid-level shortwave trough will slowly move through the central Plains today with an moderately strong mid-level jet overspreading much of Texas into the Gulf States. At the surface, a cold front is forecast to be in the Texas Panhandle at 12Z Friday and quickly accelerate southward across the entire state of Texas to near Brownsville by 12Z Saturday. ...Eastern Texas into Louisiana and southwest Mississippi... Ongoing convection is expected across much of Texas and southern Oklahoma at the beginning of the period as a result of increasing isentropic ascent resulting from the strengthening low-level jet. These morning storms are expected to move southeastward along the instability gradient into east Texas and Louisiana during the afternoon. Some additional development is possible in a warm air advection regime across south and central Louisiana this afternoon/evening. However, there is still some uncertainty regarding the strength of the low-level jet and therefore, the coverage of storms. Regardless of coverage, storms in the area will likely be elevated with some supercell structures possible given very strong 70+ kts of effective shear. These better organized supercell structures will likely pose the primary threat for large hail, however the limited instability will likely preclude more than an isolated threat. Farther west across Texas, some surface based instability is expected to develop ahead of the cold front. This instability combined with lift from the surface front may be sufficient for a few storms during the afternoon/early evening. However, most of the forcing is expected to be across Louisiana and Arkansas by late afternoon with height rises expected across central and south Texas after 21Z. In addition, the rapid southward movement of the cold front will likely limit parcel residence time and may also be a negative factor for deep convection along the front. Any storms which can develop would pose an isolated large hail and damaging wind threat. ...South Texas near the Rio Grande... Forecast soundings show much of this region capped through the evening hours, but height falls from an approaching shortwave after 06Z will increase the chances for storms late in the period. Storms will have a greater probability across the border in Mexico with the assistance of upslope flow behind the front. Forecast soundings show elevated instability for several hours post-frontal which would support a brief supercell or two late in the period with large hail as the primary threat. ...Southern Alabama and north Florida... A weak mid-level shortwave trough over Louisiana early this morning will move east-southeastward through the morning hours. As this impulse approaches a stalled surface front across north-central Florida during the morning hours, convection is expected to develop and strengthen. Temperatures are expected to warm into the mid 70s with dewpoints in the mid to upper 60s south of this warm front yielding around 1000 to 1500 J/kg MLCAPE. Strong mid-level flow in excess of 50 knots will provide ample effective shear (45+ kts) or storm organization and the potential for supercell structures. Large hail and damaging winds will be the primary threat with this activity. A strengthening low-level jet is expected to persist across the northern Gulf Friday night with a large reservoir of 1000+ J/kg MUCAPE available to feed mostly elevated storm activity along the coast. Strong shear may help maintain storm longevity within these clusters with occasional strong to isolated severe storms. The unstable upstream airmass will likely maintain this marginal severe threat through 12Z Saturday into the northern Florida Peninsula. ..Bentley/Dial.. 04/16/2021Read more
SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1252 AM CDT Fri Apr 16 2021 Valid 171200Z - 181200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL GULF COAST INTO SOUTHERN GEORGIA...AND DEEP SOUTH TEXAS... ...SUMMARY... Isolated strong to severe storms appear possible Saturday across parts of the central Gulf Coast into southern Georgia. A few instances of large hail may also occur Saturday morning across deep south Texas. ...Synopsis... A 60-80 kt mid-level westerly jet is forecast to be present over much of the Southeast Saturday. A low-amplitude shortwave trough will advance eastward from the mid MS Valley to the Mid-Atlantic through the day. A 30-40 kt west-southwesterly low-level jet should be focused over the vicinity of northern FL and southern GA through at least Saturday afternoon. At the surface, a cold front will move off the TX/LA Gulf Coast, while a weak low develops northeastward from coastal LA/MS/AL to northern FL and southern GA along a warm front. This front is not expected to make much northward progress through the day across southern GA. ...Southeast... Convection will likely be ongoing Saturday morning across the central Gulf Coast with support from a low-level jet. Limited convergence along the warm front and mid-level flow largely parallel to this boundary creates a fair amount of uncertainty regarding how much convection will develop through the day. Most guidance suggests that overall storm coverage may remain quite isolated, before possibly increasing some by late Saturday afternoon. Regardless, any storms that can form along/south of the warm front from coastal AL across the FL Panhandle and into southern GA may pose an isolated severe threat. Deep-layer shear appears strong enough to support supercells, but low-level shear may gradually decrease through the afternoon as the low-level jet veers to westerly and shifts towards the Atlantic Coast. Occasional strong to damaging winds appear possible with any surface-based convection, and a brief tornado may also occur near the warm front. Mid-level lapse rates should be relatively modest across this region, but isolated instances of large hail could also occur Saturday afternoon/evening across the warm sector as instability becomes maximized. ...Deep South Texas... A cold front will quickly progress southward across deep south TX Saturday morning. Low-level upslope flow over the mountains of adjacent northern Mexico may encourage a couple of elevated supercells to form and cross into this region around the beginning of the Day 2 period. Even though boundary-layer instability will quickly decrease behind the front, enough low-level moisture and modestly steepened mid-level lapse rates should still support around 1000-1500 J/kg of MUCAPE. This instability coupled with strong shear aloft may foster isolated large hail with any supercell that can persist for a few hours. Storms should weaken by mid morning as the elevated instability diminishes. ..Gleason.. 04/16/2021Read more
SPC Day 1 Fire Weather Outlook
Day 1 Fire Weather Outlook NWS Storm Prediction Center Norman OK 0141 AM CDT Fri Apr 16 2021 Valid 161200Z - 171200Z ...Synopsis... Moderate to strong mid-level flow is expected across the Southwest as a mid-level shortwave trough shifts eastward. At the surface, high pressure will build into the northern Rockies which will bring dry and cool weather to much of the region and offshore flow to California, Oregon, and Washington. ...Southwest... Deep mixing is expected this afternoon as temperatures warm into the upper 60s to mid 70s across southern Arizona and New Mexico into Far West Texas. This deep mixing will bring strong winds to the surface and result in 15 to 20 mph sustained winds despite a relaxed surface pressure gradient. Relative humidity is expected to range from 8 to 13 percent. ...Portions of the Northwest... Offshore flow is expected across Oregon and Washington through the day today. This continental airmass will bring relative humidity of 15 to 20 percent to areas east of the Cascades and in the 20 to 25 percent in some areas west of the Cascades. Fuels in the higher elevations are mostly still moist and in some places snow covered, but the finer fuels at lower elevation are mostly cured after limited precipitation for the past several weeks. Upper-level support gives additional concern for a large fire threat as both 850mb and 500mb flow are forecast to be 40 to 50 mph and forecast soundings show mixing to at least 850 mb. Thus, despite forecast winds of 13 to 15 mph west of the Cascades from most forecast guidance, would not be surprised to see sustained winds approaching 20 mph with higher gusts. ..Bentley.. 04/16/2021 ...Please see www.spc.noaa.gov/fire for graphic product...Read more