Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 152153
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
453 PM EST SUN JAN 15 2017

...VALID 2153Z SUN JAN 15 2017 - 12Z MON JAN 16 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
40 SSE 6R6 65 WSW SJT 30 N DYS 40 SW F05 30 ENE CDS 10 WSW HBR
20 NNE DUC 20 S ADH 30 SSE MLC 40 WNW DEQ 10 SSW TYR HYI
20 ESE UVA 15 N MMPG 55 W MMPG.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 SSW CRS 20 SSE TPL 20 W AUS 20 SSE 6R9 30 NNW 05F 20 N SEP
20 NNW RPH 10 NNW SPS 15 S DUC 20 NW GYI 15 E DUA 10 W PRX
15 ENE TRL 10 SSW CRS.


...CENTRAL AND NORTHERN TEXAS...SOUTHERN OKLAHOMA...

AT 21Z DEEP CONVECTION WAS UNFOLDING GENERALLY AS EXPECTED...WITH
THE STRONGEST CELLS...ORGANIZED INTO LINEAR STRUCTURES...OCCURRING
OVER THE CONCHO VALLEY / EDWARDS PLATEAU IN SOUTHWEST TEXAS AT THE
LATITUDE OF GREATER MIXED LAYER INSTABILITY ESTIMATED AT 500-1500
J/KG. THIS STRONG ACTIVITY WILL PRODUCE HEAVY INSTANTANEOUS RAIN
RATES...BUT THE SYNOPTICS AND CONVECTIVE MODE FAVOR FORWARD
PROGRESSION WHICH WILL CUT DOWN ON EVENT TOTALS. LARGER EVENT
TOTALS MAY OCCUR DOWNSTREAM INTO CENTRAL AND NORTH-CENTRAL TEXAS
WHERE WIDESPREAD SHOWERS IN THE STRENGTHENING DEEP LAYER ASCENT
FIELD WILL PRECEDE THE ARRIVAL OF THE STRONGER QUASI-LINEAR
CONVECTION LATER THIS EVENING. THE COMBINATION OF THESE THINGS MAY
BRING EVENT TOTALS ABOVE 2 INCHES IN SOME PLACES. IF MUCH OF THIS
RAIN OCCURS OVER ABOUT A 3 HOUR TIME SPAN...RATES COULD APPROACH
FLASH FLOOD GUIDANCE...ALTHOUGH IT IS MORE LIKELY THE RAINFALL
WILL BE SPREAD OUT OVER LONGER DURATIONS UP TO 6 HOURS...FOR WHICH
FLASH FLOOD GUIDANCE VALUES OF 3 TO 4 INCHES MAY NOT BE
ATTAINABLE. THUS...THE POTENTIAL IMPACTS MAY BE BEST DESCRIBED AS
BRIEF RAPID RUNOFF IN MANY LOCATIONS AND POSSIBLE FLASH FLOOD
CONCERNS IN THE MOST SUSCEPTIBLE BASINS.

THE POSSIBILITY OF EXCESSIVE RAINFALL EXTENDS INTO SOUTHERN
OKLAHOMA PER MODEL QPFS. GIVEN THE ORIENTATION OF THE EJECTING
NEGATIVELY TILTED SHORTWAVE TROUGH...SOME OF THE STRONGEST
MOISTURE FLUX IS FORECAST TO EVOLVE OVER NORTH-CENTRAL TX INTO
SOUTHERN OK THIS EVENING. THE REGION IS NOT ALL THAT FAR REMOVED
FROM SOURCE AIR WITH SURFACE DEWPOINTS IN THE LOWER TO MIDDLE 60S
OVER EAST TEXAS...AND RAP FORECAST SOUNDINGS PUSH PW VALUES UP
CLOSE TO 1.40 INCHES WITH GREATER THAN 500 J/KG OF MUCAPE.
CONVECTION WILL BE COMPETING WITH A LOT OF UPDRAFTS IN THIS
STRONGLY FORCED ENVIRONMENT...BUT THE PRECIPITATION MAY BE
RELATIVELY EFFICIENT. THE GREATER THREAT OVERALL...HOWEVER...WILL
LIKELY OCCUR FARTHER SOUTH INTO THE LARGER MUCAPE VALUES NEAR AND
SOUTH OF I-20.

BURKE/ORRISON
$$





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