Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 121359
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
958 AM EDT FRI SEP 12 2014

...VALID 15Z FRI SEP 12 2014 - 12Z SAT SEP 13 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
40 SW CDS 40 NNE SNK 20 WSW SWW 40 SSW SWW 20 N SJT 30 ENE SJT
50 E SJT 35 SW BWD 40 NNW 6R9 25 NW T82 20 SE JCT 15 NNE ECU
30 S E29 40 SW E29 30 NE 6R6 20 N 6R6 15 W 6R6 35 SW 6R6
55 SW 6R6 70 SSE E38 70 S MRF 65 SSW MRF 80 WSW MRF 90 N MMCU
85 N MMCU 95 NNW MMCU 115 SSW MMCS 100 SW MMCS 65 S DMN
35 SE DMN 10 ENE ALM 30 ENE SRR 50 W CVS 30 NW CVS 30 NNE CVN
35 N PVW 30 ENE PVW 40 WSW CDS 40 SW CDS.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
45 SSE CVN 35 WNW LBB 10 NE LBB 25 E LBB 40 ESE LBB 30 NW SNK
35 NW BPG 10 NNE ODO 25 SSE INK 35 WNW PEQ 30 ESE GDP 25 E GDP
CNM 25 ESE ATS 45 E ROW 50 E ROW 45 SSE CVS 45 SSE CVN.

MADE NO CHANGE TO THE PREVIOUS ISSUANCE HERE..MAINTAINING THE
FAIRLY LARGE SLIGHT TO MODERATE RISK AREA.  CONVECTION CONTINUES
TO ENHANCE THIS MORNING ALONG AND TO THE SOUTH OF THE REINFORCING
SHOT OF COLD AIR SINKING SOUTHWARD ACROSS THE SOUTHERN HIGH
PLAINS.  LOW LEVEL SOUTHEASTERLY FLOW IS EXPECTED TO BACK TO A
MORE NORTHEASTERLY DIRECTION EARLY THIS PERIOD AND STRENGTHEN.
THIS STRENGTHENING LOW LEVEL UPSLOPE FLOW IN AN AXIS OF ABOVE
AVERAGE PW VALUES---1.5 TO 2+ STANDARD DEVIATIONS ABOVE THE
MEAN---WILL SUPPORT CONTINUED HEAVY TO LOCALLY EXCESSIVE RAINFALL
AMOUNTS ACROSS SOUTHERN TO SOUTHEASTERN NM INTO WEST TO SOUTHWEST
TX.  IN AREA OF SLOW MOVEMENT OF CELLS---ISOLATED 2-3" RAINFALL
AMOUNTS IN AN HOUR OR TWO POSSIBLE.


...NORTHCENTRAL/NORTHEASTERN TX INTO SOUTHERN OK AND SOUTHWESTERN
AR...

SOME CONTINUED WEAK SOUTHWESTERLY LOW LEVEL JET INTO THE FRONTAL
BOUNDARY DRAPED THRU THIS REGION..ALONG WITH A VERY MOIST AIR MASS
POOLED VICINITY OF THE BOUNDARY..WILL SUPPORT SOME ADDITIONAL
HEAVY TO ISOLATED VERY HEAVY RAINS GENERALLY NEAR THE RED RIVER.
THE 12Z RAOBS HAD A 42 K INDEX (ALONG WITH A PW OF 2.14") AT
FWD..INDICATING JUST HOW MOIST AND UNSTABLE THE AIR MASS IS IN
THIS REGION.  MODEL GUIDANCE IS IN GOOD AGREEMENT THAT THE
REINFORCING SHOT OF COLD (AND DRIER) AIR WILL BE MOVING THRU THIS
AREA LATER THIS AFTERNOON..SO THE HEAVY RAINFALL THREAT SHOULD
LAST UNTIL EARLY TO MID AFTERNOON.  SOME LOCAL 1 TO 2 INCH
RAINFALL AMOUNTS POSSIBLE IN A COUPLE/SEVERAL HOURS..WHICH MAY
CAUSE SOME RUNOFF PROBLEMS IN AREAS THAT RECEIVED SOME OF THE
HEAVIER RAINS YESTERDAY/LAST NIGHT.


...SOUTHERN MID ATLANTIC INTO THE SOUTHERN APPALACHIANS...

THE SURFACE FRONTAL BOUNDARY PRESENTLY SINKING SOUTHEASTWARD
THROUGH THE MID ATLANTIC WILL BECOME STATIONARY LATER FRIDAY FROM
THE SOUTHERN MID ATLANTIC INTO THE SOUTHEAST.  THIS FRONT WILL
LIKELY REMAIN A FOCUS FOR HEAVY RAINFALL POTENTIAL AS UPPER
DIFFLUENCE MAXIMUM ALONG THE SOUTHERN EDGE OF THE WESTERLIES
ENHANCE UVVS IN THE AXIS OF 2.00-2.25"+ PW VALUES FORECAST TO
PERSIST ALONG THIS BOUNDARY.  MODEL CONSENSUS IS FOR THE MAX QPF
AXIS ALONG THE NC COAST INTO COASTAL SC WHERE CONVECTION WILL
LIKELY MAXIMIZE.  ISOLATED RUNOFF ISSUES POSSIBLE ACROSS THESE
AREAS FROM SHORT TERM PRECIPITATION TOTALS OF 1-3"+.  A SECONDARY
PRECIPITATION MAX TO THE NORTH OF THIS FRONT POSSIBLE OVER THE
SOUTHERN APPALACHIANS WHERE POST FRONTAL LOW LEVEL EASTERLY FLOW
WILL FOCUS.  THE HI RES RUNS ARE MOST EMPHATIC ABOUT ISOLATED VERY
HEAVY PRECIP TOTALS OVER THE SOUTHERN APPALACHIANS IN THE VICINITY
OF FAR NORTHEAST GA---UPSTATE SC INTO SOUTHWESTERN NC.  HERE
TOO---ISOLATED RUNOFF ISSUES MAY DEVELOP WHERE ANY UPSLOPE
PRECIPITATION BECOME SLOW MOVING---PRODUCING ISOLATED SHORT TERM
TOTAL OF 1-2"+

TERRY
$$





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