Quantitative Precipitation Forecast
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FOUS30 KWBC 142234
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
634 PM EDT MON AUG 14 2017

...VALID 01Z TUE AUG 15 2017 - 12Z TUE AUG 15 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
55 SW BNA 30 SSE GLW 10 SSE 1A6 25 WSW I16 10 SSE W22 10 S W99
25 ENE HSP 15 S ROA 20 NE GSO 15 SW LHZ 15 NW ECG 30 SSE EDE
20 WNW EWN CPC 45J 20 S EHO 30 W CEU 15 S RMG TCL 40 N TVR
15 S ELD 10 ESE LBR ADM 15 W CQB 15 E GCM 15 SE HRO 20 ESE M19
10 SSE NQA 55 SW BNA.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
55 SE SAD 30 ESE DUG 45 S DUG 65 SSE OLS 15 W OLS 20 NNW DMA
35 ENE IWA 45 ESE PRC 40 S FLG 20 SW INW 25 WNW SJN 70 WNW TCS
40 WNW TCS 45 E SAD 55 SE SAD.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 WSW LRJ 15 ESE CIN 20 SE MIW 15 ENE EFT 15 SSE BUU 25 NW C75
30 SSE OTM 15 SE ICL 20 SSW LNK 15 E HDE 15 S BBW 20 ENE ONL
20 WSW LRJ.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 W 2GL 20 SSE ARA 10 W CWF ACP 20 NW HDC 25 E NBG 15 W 2GL.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 SE MMCS 30 E LRU 45 NNW HMN 30 W 4CR 35 NNW ROW 30 NNE CNM
30 NNW E38 40 SW MRF 20 SE MMCS.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 ENE SGT 35 NNE TUP 10 E MDQ 15 W BHM 30 SE GWO 20 NNW ELD
15 WSW DEQ 20 SE MLC MKO 35 SSW HRO 30 ENE SGT.


...LOWER MISSISSIPPI VALLEY / OK/TX/AR/MS/TN/LA...

THE PRIMARY CONCERN HERE IS TRANSPORT AND CONVERGENCE OF
MODERATELY UNSTABLE AIR IN TOWARD AN MCV THAT WAS MOVING DUE EAST
OUT OF EASTERN OKLAHOMA AS OF LATE AFTERNOON. GIVEN EARLIER
RAINFALL AND CLOUD COVER...ANY CONVECTION THAT WAS ONGOING AT 22Z
WAS LIKELY SOMEWHAT ELEVATED. ALTHOUGH A FEW SURFACE BASED STORMS
ARE POSSIBLE THIS EVENING NEAR THE MCV AND TRAILING TROUGH AXIS
INTO NORTHEAST TEXAS...THE MAIN FLASH FLOOD POTENTIAL WILL LIKELY
OCCUR WHEN ELEVATED STORMS REFORM WHERE LOW LEVEL FLOW ACCELERATES
AND CONVERGES AHEAD OF THE MCV OVER PRIMARILY SOUTHERN AND CENTRAL
ARKANSAS FROM LATE EVENING ONWARD. MOST UNSTABLE CAPE VALUES OF AT
LEAST 1000 J/KG ARE EXPECTED...COUPLED WITH ANOMALOUSLY RICH
MOISTURE AT OR ABOVE 2 INCHES. THE ENVIRONMENT ALONE SHOULD YIELD
EXTREME SHORT TERM RAIN RATES AND LOCAL 2-PLUS INCH TOTALS OVER A
SHORT TIME. IN AREAS WHERE CONVECTION ALIGNS WEST TO
EAST...HOWEVER...AT THE NOSE OF THE LOW LEVEL FLOW...TRAINING
COULD LEAD TO MORE GREATLY EXCESSIVE TOTALS...SUCH AS IN THE NSSL
WRF SOLUTION WHICH SIGNALS MORE THAN SEVEN INCHES IN SPOTS. FLASH
FLOOD GUIDANCE WAS ALREADY LOWERED IN THIS REGION BY EARLIER
RAINFALL.


...EASTERN TENNESSEE INTO NORTH CAROLINA...

A FEW SLOW MOVING CELLS NEAR THE OUTER BANKS OF NORTHEAST NORTH
CAROLINA WERE PRODUCING RADAR-ESTIMATED 1.5 INCH PER HOUR
RAINFALL. STREET FLOODING IS CERTAINLY POSSIBLE.
OTHERWISE...ATTENTION IS ON THE LOW AMPLITUDE SHORTWAVE TROUGH
MOVING THROUGH EASTERN TENNESSEE. THIS SHOULD SUPPORT POCKETS OF
STRONG CONVECTION AND CONVECTIVE RAIN RATES FROM EASTERN TN INTO
NC THIS EVENING...PER MOST OF THE MODEL GUIDANCE AND RECENT RAP
RUNS. DEEP LAYER FLOW IS DECIDEDLY WESTERLY WHICH SHOULD PROMOTE
FORWARD MOTION AND NOT TOO MUCH OF A TRAINING CONCERN...ALTHOUGH
THE VERY MOIST AND MODERATELY UNSTABLE ENVIRONMENT COULD SUPPORT
RAINFALL PRODUCING FLASH FLOODING IN ANY SUSCEPTIBLE LOCATIONS.


...SOUTHWEST TEXAS...

CONVECTION NEAR THE DAVIS MOUNTAINS AND BIG BEND REGION WAS
OCCURRING IN A PLUME OF DEEPER MOISTURE PER WATER VAPOR
IMAGERY...AND NEAR A REMNANT MCV FROM PRIOR CONVECTION. DEEP LAYER
FORCING IS NOT PARTICULARLY WELL FOCUSED...BUT WITH PRECIPITABLE
WATER VALUES SOMEWHAT GREATER THAN NORMAL...THERE IS A RISK OF
LOCAL FLASH FLOODING THROUGH LATE EVENING.

GRAPHICS AVAILABLE ON THE WEB AT WWW.WPC.NCEP.NOAA.GOV

BURKE
$$





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