Quantitative Precipitation Forecast
Issued by NWS

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

000
FOUS30 KWBC 050027
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
726 PM EST MON DEC 04 2017

...VALID 01Z TUE DEC 05 2017 - 12Z TUE DEC 05 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 NNE M19 35 NNE BYH 45 WSW HOP 35 SSW CKV 45 S MKL 25 S GLH
25 ENE BAD 15 SSE 4F4 15 SSW LBR 10 W MWT 30 NNW LRF 20 NNE M19.


...LOWER MISSISSIPPI VALLEY...

...05/01Z UPDATE...
00Z RADAR LOOPS SHOWED A NEAR SOLID BUT FAIRLY NARROW BAND OF
THUNDERSTORMS CONTINUING TO PROGRESS EWD ALONG A FAIRLY STG COLD
FRONT FROM MO SWWD INTO SE OK.  OTHER MORE SCTD STORMS WERE
BEGINNING TO DVLP IN ADVANCE OF THIS MAIN LINE WITHIN A SOMEWHAT
BETTER DEFINED 85H LOW LEVEL JET ACROSS EXTREME NE TX INTO AR.
OVERALL THINKING HERE REMAINS UNCHANGED WITH EXPECTED RATHER QUICK
PROGRESSION OF SYSTEM COUPLED WITH ONLY WEAK INSTABILITY AND MDTLY
HI AMBIENT DRY SOIL CONDITIONS MINIMIZING ANY ORGANIZED FLASH
FLOOD THREAT.  RECENT HRRR RUNS INDICATE ISOLATED RAINFALL AMOUNTS
POSSIBLY APPROACHING 2 INCHES..WITH MOST OF THAT OCCURRING IN A 1
TO 2 HOUR PD.  THIS MAY LEAD TO SOME ISOLATED SHORT LIVED RUNOFF
ISSUES..BUT FOR MOST AREAS...FLASH FLOOD THREAT IS MINIMAL.
SULLIVAN



...14Z UPDATE...

MANY OF THE POINTS MADE IN THE 0830Z EXCESSIVE RAINFALL DISCUSSION
WERE STILL VALID AT THIS POINT...AND NO CHANGES WERE MADE TO THE
AREAL OUTLINE ISSUED EARLIER.

A QUICK LOOK AT THE 12Z SOUNDINGS ACROSS THE REGION SUGGEST THAT
THE 00Z AND 06Z MODEL RUNS WERE ON THE RIGHT TRACK IN TERMS OF THE
LOW LEVEL MOISTURE PROFILES AND LOW LEVEL WINDS.  DESPITE THE FACT
THAT SOME PRECIPITATION WAS ALREADY DEVELOPING IN AND NEAR TO THE
MARGINAL RISK AREA AS OF 14Z...THINK THAT CONDITIONS ACROSS THIS
AREA WILL BE FAIRLY BENIGN INTO THE AFTERNOON.  AT THAT POINT...A
LINE OF THUNDERSTORMS IS EXPCTED TO FORM ALONG A WELL DEFINED COLD
FRONT.  AGREE WITH THE PREVIOUS FORECASTER THAT THE THREAT FOR
EXCESSIVE RAINFALL WILL BE MINIMIZED BY WEAK INSTABILITY AND DRY
ANTECDANT CONDITIONS...BUT THAT THERE IS AT LEAST SOME POTENTIAL
FOR SHORT-LIVED RAPID RUNOFF PROBLEMS IN A FEW SPOTS.

BANN


...PREVIOUS DISCUSSION...

ASSOCIATED WITH THE DEVELOPING NORTHERN PLAINS CYCLONE...LARGE
SCALE HEIGHT FALLS ARE SET TO OCCUR MAINLY NORTH OF INTERSTATE
40...BUT A SURGING STRONG COLD FRONT WILL ENCOUNTER A FEW HUNDRED
J/KG OF MUCAPE IN AREAS FARTHER SOUTH...AND THE HI-RES MODELS
SUGGEST THIS WILL SUPPORT EVOLUTION INTO A LENGTHY NARROW SQUALL
LINE ADVANCING THROUGH THE MISSISSIPPI VALLEY. THE AREA NEAR THE
ARKLATEX HAS THE ADVANTAGE OF SOMEWHAT GREATER INSTABILITY AND
SOME PADDING FROM EARLY MORNING WARM ADVECTION-FORCED
PRECIPITATION TO BOOST 24-HOUR TOTALS. AREAS DOWNSTREAM TOWARD
WESTERN TENNESSEE SHOULD SEE A LITTLE BETTER DEVELOPED SQUALL LINE
WITH SOME TRAILING STRATIFORM REGION...ALONG WITH SOMEWHAT
LINGERING MID LEVEL CONFLUENCE. THUS...WPC IS FORECASTING AREAL
AVERAGE 0.75 TO 1.25 INCHES FROM FAR NORTHEAST TEXAS THROUGH
SOUTHERN ARKANSAS AND INCLUDING PARTS OF LA/MS/TN. THE THREAT OF
FLASH FLOODING SHOULD BE MINIMIZED BY THE WEAK INSTABILITY...QUICK
PROGRESSION...AND RECENT DRY WEATHER...BUT SINCE THE BULK OF THE
RAINFALL WILL OCCUR IN ONLY A 1 TO 2 HOUR DURATION AT ANY GIVEN
LOCATION...THERE IS SOME POTENTIAL FOR SHORT-LIVED RAPID RUNOFF IN
THE MOST HYDROLOGICALLY SUSCEPTIBLE LOCATIONS.

BURKE

$$





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.