Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 131459
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1059 AM EDT SUN AUG 13 2017

...VALID 15Z SUN AUG 13 2017 - 12Z MON AUG 14 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
45 S OLS 70 WSW TUS 10 ESE GBN BLH 40 E NXP 30 ESE HND 40G
40 ESE INW 25 SSE GUP 10 E GNT 45 S ABQ 25 NNW 4CR 40 SSE LVS
15 SSW RTN 20 ENE VTP LIC 15 WSW GLD 45 NNW GCK 30 S DDC
35 NW JWG OKC 10 ENE ADH 10 WNW RKR 20 S HRO 15 N ARG 35 ENE DYR
35 NNE TUP 35 SE GWO HKS 25 NNW MCB 10 S HDC 15 NE BVE
25 SSW KMIS 20 NNW KMDJ 30 WSW 9F2 15 W P92 15 NW LFT 15 WSW DRI
20 WSW JAS 35 NE CLL 10 SW GDJ 20 N DYS 10 W SWW 40 S BPG
40 N 6R6 50 SE E38 40 S E38 100 N MMCU 105 SW MMCS 75 S DUG
45 S OLS.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 N RWI 15 ESE NTU 45 ENE 9W7 30 E FFA 30 NE HSE HSE 20 E MRH
SUT 20 SW MYR 40 SW MYR 25 NNW CHS OGB CAE 30 N CUB 15 S VUJ
20 NNW SOP LHZ 15 N RWI.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 NNW DTL 25 SSW KBAC 8D3 15 SW PKD 30 NNW DTL.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 S DEQ 20 NW MWT 20 NW SRC 15 S UTA 20 SSE GLH 30 SSW MLU
30 NNE OCH 15 N PSN 30 E LNC 15 SW SLR 15 S DEQ.


...SOUTHWEST...

MODEST HEIGHT FALLS WILL BE APPROACHING CA AND GRADUALLY SAGGING
SOUTHWARD IN ASSOCIATION WITH AN UPPER JET THROUGH TONIGHT.  STILL
CONCERNED ABOUT THE AMOUNT OF MOISTURE STILL LINGERING OVER PARTS
OF THE DESERT SOUTHWEST AND HAVE PULLED THE MARGINAL RISK BACK TO
THE WEST BASED ON THE 12Z SOUNDINGS FROM KVEF AND KPSR. FORECAST
SOUNDINGS STILL SUGGEST THAT THUNDERSTORMS WHICH DEVELOP LATER
TODAY AND THIS EVENING WILL BE ORGANIZED ENOUGH TO PRODUCE LOCALLY
HEAVY TO POSSIBLY EXCESSIVE RAINFALL IN AREAS OF CENTRAL/WESTERN
AZ WHICH RECEIVED HEAVY RAINFALL LAST NIGHT.  THERE SHOULD BE A
SHIFT IN THE FLOW PATTERN LATE TONIGHT OR EARLY MONDAY MORNING
WHICH BRINGS DRIER AIR INTO THE REGION...SO THINKING IS THAT THE
TIMING OF HEAVIEST RAINFALL SHOULD BE FROM LATER THIS AFTERNOON
THROUGH THE EVENING.


...S-CENTRAL PLAINS TO LOWER MS VALLEY....

RADAR SHOWED A COMPLEX MAINLY CONFINED TO AR AND A SMALL PORTION
OF NORTHEAST TX THIS MORNING. CLOUD TOPS WERE WARMING AND THE MAX
REFLECTIVITY IN RADAR IMAGERY HAS BEEN TAPERING OFF.  TRIMMED THE
WESTERN BOUNDARY OF THE SLIGHT RISK TO FIT THE BACK EDGE OF THE
COMPLEX WHILE LEFT THE REMAINDER OF THE SLIGHT RISK IN PLACE.
BASED ON A QUICK LOOK AT THE LATEST HRRR AND THE 12Z NAM
CONEST...SEE SOME MODERATE TO HEAVY RAINFALL SIGNALS APPROACHING
PARTS OF WESTERN TN SO EXPANDED THE MARGINAL RISK A BIT TO THE
EAST OF THE PREVIOUS FORECAST.  WITH 12Z SOUNDINGS AND BLENDED TPW
SATELLITE IMAGERY STILL SHOWING AN AXIS OF PW VALUES AT OR ABOVE 2
INCHES EXTENDING BACK TO THE SOUTHEAST OF THERE...SO MADE NO
CHANGES THERE WITH RESPECT TO THE MARGINAL RISK.

...ERN CAROLINAS...

LINGERING IMPULSE ENERGY WITHIN A SLOW TO DISLODGE CAROLINAS TO
SERN US/CENTRAL GULF COAST DEEP MOISTURE AXIS WITH PWS AOA 2
INCHES SHOULD AGAIN FIRE CLUSTERS OF EHNANCED CONVECTION DAY1 IN A
REGION OF FAVORABLE RIGHT ENTRANCE REGION UPPER JET LIFT AND
INSTABILITY ALONG THE SAGGED/WAVY TRAILING FRONTAL ZONE.
PREDICTABILITY OF SPECIFICS OF CONVECTIVE FOCUS THOUGH IS NOT
HIGH...BUT AVAILABLE MOISTURE SUGGESTS A MARGINAL RISK OF
LOCALIZED RUNOFF ISSUES.

...UPPER MIDWEST...

INTRODUCED A MARGINAL RISK ACROSS A SMALL PORTION OF SOUTHEAST ND
INTO NORTHWEST MN WHERE FLASH FLOOD GUIDANCE IS AT OR SOMEWHAT
BELOW 1.5 INCHES PER 3 HOURS.  THIS AREA IS ALONG AND AHEAD OF A
MID LEVEL VORT CENTER MOVING SLOWLY EASTWARD WITH SOME ENHANCED
RAINFALL RATES NEAR ITS CENTER THIS MORNING.

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

BANN

$$





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