WPC Met Watch |
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Mesoscale Precipitation Discussion: #0990 (2018) |
(Issued at 854 AM EDT Fri Oct 19 2018
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MPD Selection |
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Mesoscale Precipitation Discussion 0990...Corrected
NWS Weather Prediction Center College Park MD
854 AM EDT Fri Oct 19 2018
Corrected for typos
Areas affected...Central to Northeast TX
Concerning...Heavy rainfall...Flash flooding possible
Valid 191246Z - 191846Z
Summary...An increase in hourly rain totals to 0.5"+ with local
amounts of 1-2" is expected during the next several hours over
saturated soils, which would enhance flooding across a saturated
region.
Discussion...Water vapor imagery shows a shortwave moving
northeast through the TX Panhandle at this time. Infrared imagery
reveals a slow cloud top cooling across the region the past few
hours to the northwest of an inverted trough extending north from
an area of low pressure just offshore the TX coast, which is
leading to a slow increase in hourly rain totals/rates.
Precipitable water values are ~1.75" per recent GPS data. Inflow
at 850 hPa is slightly convergent out of the south-southwest at
20-25 kts per VAD wind profiles, which is importing MU CAPE values
of 100-500 J/kg into the region.
The 06z HREF probabilities of 0.5" an hour are forecast come up in
this area, exceeding 50% in a spotty manner through 19z. This
fits the available moisture and MU CAPE, which should be able to
support 0.5" an hour rates from any showers and thunderstorms that
form in this environment. The mesoscale guidance indicates the
potential for 1-2" of rain during the next six hours. Despite a
slow upward return in flash flood guidance values, two week
precipitation anomalies are 600%+ of average, which implies
significant soil saturation. Discussions with the local forecast
offices in the area (FWD/Fort Worth and SJT/San Angelo) indicate
the potential for virtually all the rain to be in the form of
runoff, enhancing the flood threat over the next several hours.
Flash flooding is possible if the guidance is underselling the
potential.
Roth
ATTN...WFO...FWD...SHV...SJT...
ATTN...RFC...LMRFC...WGRFC...
LAT...LON 33349594 33009543 32869531 32029614 30979727
31139924 32249880 33329709
Last Updated: 854 AM EDT Fri Oct 19 2018
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