SPC Apr 9, 2020 0600 UTC Day 1 Convective Outlook
(Do, 09 Apr 2020)
SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1220 AM CDT Thu Apr 09 2020
Valid 091200Z - 101200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE TEXAS COASTAL PLAINS...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MID-ATLANTIC INTO SOUTHEASTERN NEW YORK...
Severe thunderstorms associated with very large hail and damaging
wind gusts are expected from the southern Texas Hill Country onto
the Texas Coastal Plains this afternoon and evening. Damaging wind
gusts may also occur around midday in the Washington D.C. and New
York City vicinities.
....Southern Texas Hill Country/Texas Coastal Plains...
At mid-levels, heights will fall as a low-amplitude upper-level
ridge because much less amplified. A subtle shortwave trough will
move eastward through the ridge across central and east Texas. At
the surface, a cold front will move southeastward across the Texas
Hill Country today. The boundary will be a focus for convective
development this afternoon and evening. Ahead of the front, surface
dewpoints in the lower 70s F will aid strong destabilization as
surface temperatures warm. MLCAPE is forecast to reach the 3000 to
4000 J/kg range by afternoon. Increasing low-level convergence along
with large-scale ascent associated with the shortwave trough, will
help storms to develop early this afternoon across southern parts of
the Texas Hill Country. This convection is forecast to grow upscale,
moving east-southeastward into the Texas Coastal Plains late this
afternoon into this evening.
In addition to the strong instability, RAP forecast soundings this
afternoon across the Texas Coastal Plains show strong speed shear in
the mid-levels. 0-6 km shear is forecast to be in the 45 to 50 kt
range with 700 to 500 mb lapse rates near 7.0 C/km. This should be
favorable for supercells with large hail. Hailstones greater than 2
inches in diameter will be possible with the more dominant storms
close to localized maxima in instability. 0-3 km lapse rates are
forecast to peak near or above 8.5 C/km in the late afternoon. This
will be favorable for damaging wind gusts with supercells and
intense multicell line segments. The greatest potential for severe
storms is expected to be from between Corpus Christi and San Antonio
northeastward to the Houston area. The severe threat could impact
the immediate Texas Coast during the evening as the cold front
...Southeast New York/Mid-Atlantic/Carolinas...
An upper-level trough will move quickly eastward into the upper Ohio
Valley this morning. An associated 100 to 120 kt mid-level jet will
move through the base of the trough with the exit region of the jet
overspreading the Mid-Atlantic region. At the surface, a cold front
will advance quickly eastward across the central Appalachians this
morning. Surface dewpoints ahead of the front should be in the mid
to upper 50s F, allowing for weak instability to develop. As strong
large-scale ascent moves into the region form the west, low-topped
thunderstorms should initiate and move quickly eastward toward the
coast. Due to very strong wind speeds in the low to mid-levels, this
convection should be able to produce damaging wind gusts. Although
the greatest threat should be from the vicinity of Washington D.C.
to near New York City, marginally severe wind gusts will also be
possible in southern New England and southward into Virginia and the
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SPC Apr 9, 2020 0600 UTC Day 2 Convective Outlook
(Thu, 09 Apr 2020)
SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1223 AM CDT Thu Apr 09 2020
Valid 101200Z - 111200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM SOUTHEAST
NM INTO WEST TX...
Some threat for isolated strong thunderstorms may evolve on Friday
into Friday night across west Texas and southeast New Mexico. Hail
would be the primary hazard with any severe activity.
The cutoff upper low over the Southwest is forecast to begin moving
eastward on Friday afternoon into Friday night. A deep upper trough
over the eastern CONUS should continue moving eastward. At the
surface, low pressure is forecast to gradually deepen across the
central High Plains by afternoon, while a ridge moves southeastward
from the central Plains into the Southeast.
...West TX into southeast NM...
Low-level flow is forecast to veer to southeasterly across
central/south TX into west TX/eastern NM on Friday, as the ridge
shifts eastward. As this occurs, low-level moisture over the western
Gulf will begin to advect northwestward, as a surface trough becomes
an effective dryline somewhere over west TX or eastern NM.
Uncertainty remains regarding the magnitude of low-level moisture
return by Friday afternoon/evening. If sufficient moisture can
advect northwestward, then isolated surface-based thunderstorm
development will be possible across some portion of west TX and
perhaps into southeast NM. Any such development would pose some hail
risk. Some hail threat may also evolve from elevated convection
later Friday night across a broader portion of west TX, as moisture
continues to slowly increase beneath steep midlevel lapse rates.
Hail would be the primary hazard with any such activity.
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