U.S. Severe Weather Forecast (Convective Outlook)

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Day Three

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Storm Prediction Center ac 231943 


Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0143 PM CST Wed Jan 23 2019 


Valid 232000z - 241200z 


..there is a slight risk of severe thunderstorms across portions of 
the central Gulf Coast region and vicinity... 


... 
Isolated damaging winds and a couple of tornadoes remain possible 
from the central Gulf Coast region this afternoon, to west central 
Florida late tonight. 


... 
Aside from adjustments to the western fringe of the outlook areas 
for convective progression over the past few hours, the outlook will 
otherwise remain unchanged. As per latest forecast reasoning, 
potential for a couple of damaging wind events, and possibly a 
tornado or two, will continue shifting eastward across the region 
through tonight. 


.Goss.. 01/23/2019 


Previous discussion... /issued 1023 am CST Wed Jan 23 2019/ 


..northern Gulf Coast today to west central Florida early Thursday... 
An initial midlevel shortwave trough is ejecting northeastward 
toward the Great Lakes, while an upstream wave over Texas translates 
eastward toward the lower MS valley. Weak surface cyclogenesis 
should be maintained through the period in advance of this southern 
shortwave trough, from MS this morning to the Piedmont of the 
Carolinas by early Thursday. Strong low-level southerly flow in 
advance of the weak surface low and associated cold front will 
continue to advect a plume of 65-70 f boundary-layer dewpoints 
inland from the central Gulf of Mexico and western Caribbean Sea. 
This moisture will support thunderstorms along and in advance of the 
cold front through tonight across the north central and northeast 
Gulf states. 


Per the 12z lix and rap/NAM forecast soundings, surface temperatures 
near 70 f and dewpoints of 65-67 f will be necessary to remove the 
near-surface stable layer. However, the relatively cool shelf 
waters and widespread clouds inland will help maintain the 
near-surface stable layer. Low-level and deep-layer vertical shear 
will be favorable for supercells, with effective srh greater than 
400 m2/s2 and effective bulk shear greater than 50 kt. This 
scenario appears to be right on the margins for truly surface-based 
convection inland, thus will maintain the outlook areas for the 
threat for tornadoes and/or damaging gusts. Gradual destabilization 
is expected tonight across FL, with some potential for the stronger 
storms to reach the corridor from Tampa to Jacksonville from 09-12z. 


$$ 

Mesoscale Discussion


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Storm Prediction Center mesoscale discussion 240000 
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Mesoscale discussion 0049 
National Weather Service Storm Prediction Center Norman OK 
0600 PM CST Wed Jan 23 2019 


Areas affected...portions of northeast New York...central and 
northern Vermont...central and northern New Hampshire...extreme 
western Maine 


Concerning...freezing rain 


Valid 240000z - 240400z 


Summary...freezing rain remains likely for much of the area for the 
next few hours, with accumulations rates of up to 0.05 in/3 hrs 
possible. 


Discussion...a mid-level shortwave trough and associated surface 
cyclone will traverse the area this evening, providing deep-layer 
ascent. Simultaneously, a conveyor belt of deep moisture and 
associated precipitation will continue to overspread the region, 
with sfc-700 mb warm air advection slowly moistening/warming temperatures 
throughout the lower troposphere. While surface/low-level 
tropospheric temperatures for much of the area will eventually rise 
above the freezing mark, temperatures currently remain well below 
freezing, especially across northern portions of Vermont and New 
Hampshire. With 10+ f T/TD spreads noted across the area, 
evaporative cooling will promote wet-bulb temperatures to persist 
below 0c for at least the next 2-4 hours, fostering a short-term 
freezing rain threat to continue. 


Rap point forecast soundings and ensemble model guidance suggest 
that the freezing rain threat will likely continue to at least 
0400z, where a transition to all rain is expected. 


.Squitieri.. 01/24/2019 


..please see www.Spc.NOAA.Gov for graphic product... 


Attention...WFO...gyx...btv...aly... 


Latitude...Lon 43277225 43207299 43247369 43697420 44517398 44987359 
44997152 44897098 44437087 43467193 43277225