U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 220549 
Storm Prediction Center ac 220547 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1247 am CDT Mon Jul 22 2019 

Valid 221200z - 231200z 

..there is a slight risk of severe thunderstorms from portions of 
the northern middle-Atlantic into southern New England... 

Severe thunderstorms capable of damaging wind gusts are expected 
from the northern mid-Atlantic into southern New England today. 

The shortwave trough currently moving through the upper Midwest will 
continue eastward across the upper Great Lakes/lower Ohio Valley 
today, reaching the upper Ohio Valley/lower Great Lakes by early 
Tuesday morning. At the same time, upper ridging centered over The 
Four Corners will build northward. The evolution of these features 
will result in a highly amplified western Continental U.S. Ridge/eastern Continental U.S. 
Trough pattern by the end of the period. 

At the surface, a cold front currently extends from northwest OK 
northeastward across southern MO through the central Ohio Valley into 
central PA. Western portion of this front is expected to continue 
progressing southward/southeastward. Eastern portions of this front 
are also expected to move southward/southeastward, although with 
slowly forward progress. By early Tuesday morning, this front is 
expected to extend from the Texas Hill country eastward across the 
lower MS valley and then northeastward into the northern 

..northern mid-Atlantic into southern New England... 
Dewpoints in the low 70s are expected to be in place from northern 
Virginia/Delmarva Peninsula into southern New England ahead of the 
approaching cold front. Expectation is for showers and thunderstorms 
along the front to gradually increase in strength and coverage as 
they encounter this more moist and unstable air mass. In addition to 
this more favorable low-level moisture, a deepening surface low 
along the front will help strengthen surface convergence while the 
approaching shortwave trough provides modest large-scale forcing for 
ascent. The strongest vertical shear will be displaced north of the 
frontal zone, but vertical shear along the front is still expected 
to be strong enough for occasional updraft organization. A 
predominantly linear, multicell Mode is anticipated with damaging 
wind gusts as the primary severe threat. Some isolated hail is also 
possible. A non-zero tornado threat also exists, particularly near 
the surface low and any backed surface winds. 

..mid-south through the Tennessee Valley... 
Ongoing convective cluster across MO is expected to gradually drift 
southeastward this morning, eventually contributing to thunderstorm 
development across the mid-south as it encounters a moist and 
diurnally destabilizing air mass. Vertical shear across the region 
will be weak but some localized enhancement of the low/mid-level 
flow is possible near the mesoscale convective vortex. Strength of the mesoscale convective vortex will dictate the 
severe coverage. Current expectation is for a few damaging wind 
gusts within the strongest storms. 

..southern/Central High plains... 
Thunderstorms are expected to develop across the higher terrain of 
the southern and Central High plains this afternoon. While the air 
mass across the Front Range is not expected to be as unstable as the 
past few days, a severe storm or two is still possible, particularly 
across the Central High plains where stronger upper flow will result 
in more favorable vertical shear. 

.Mosier/Bentley.. 07/22/2019 


Mesoscale Discussion

acus11 kwns 220441 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 220440 

Mesoscale discussion 1567 
National Weather Service Storm Prediction Center Norman OK 
1140 PM CDT sun Jul 21 2019 

Areas affected...northeast OK into southwest MO and northwest Arkansas 

Concerning...Severe Thunderstorm Watch 537... 

Valid 220440z - 220545z 

The severe weather threat for Severe Thunderstorm Watch 537 

Summary...overall weakening trend is expected to continue with 
storms shifting southeast across the mesoscale discussion area late this evening. A 
few strong gusts are possible in the short term, but the overall 
severe threat has diminished. Ww 537 is expected to expire as 
scheduled at 05z. 

Discussion...radar trends over the last hour or so indicate gradual 
weakening is occurring with line of storms extending across 
northeast OK into southwest MO. Both 5 and 9 km cappi has shown a 
marked decrease in reflectivity. Severe gusts of 58 mph were last 
measured near Talala in Rogers County OK about 40 minutes ago. Other 
regional observations indicate wind gusts in the 35-45 kt range. As 
storms continue southeast across northeast OK and into northwest Arkansas 
expected continued weakening with some gusty winds possible. Where 
counties remain in ww 537 across parts of southwest MO, a few strong 
gusts are possible, but as boundary layer inhibition has increased, 
severe threat has become quite limited. A downstream watch is not 
expected and ww 537 will expire at 05z. 

.Leitman.. 07/22/2019 

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


Latitude...Lon 36349633 37029437 37489334 37549248 37049213 36459204 
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