Quantitative Precipitation Forecast
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FOUS30 KWBC 210653
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
252 AM EDT FRI JUL 21 2017

...VALID 12Z FRI JUL 21 2017 - 12Z SAT JUL 22 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
85 NNW MMHO 60 SW OLS 35 WNW OLS 40 SE CGZ 10 NE SDL 25 NW PRC
65 SSE SGU 20 ENE CDC 40 ESE U24 35 E PVU 30 ENE FIR 10 W RWL
10 NE CYS 15 SW AKO 10 ESE PUB 15 W LVS 20 W 4CR 30 WNW GDP
30 W MRF 90 SSW MRF 80 E MMCU.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
75 E CWCF 30 ESE CWEA 15 NE FGN 25 WNW ASX 20 N MOP 10 SW LPR
20 SSW EKN LWB 20 NW 6V3 10 SSW HUF 25 SW PIA MUT 15 NNE AMW
15 NNW TQE 20 S BVN 20 N LXN 15 SW TIF 25 ESE ICR 45 SE MBG
15 ENE MBG 40 ESE CWIK.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
75 SSE OLS 20 SSE OLS 15 ESE DMA 40 ESE IWA 55 ESE PRC 30 S 40G
20 WNW GCN 60 ESE SGU 35 W PGA 25 SSE INW 25 N SOW 35 SSW RQE
20 WNW CEZ 10 SE EEO 40 SW LAR 10 NE BJC 10 ENE MNH 45 E MYP
25 W ALS 35 NNW SAF 45 WNW TCS 30 S DMN 115 ESE DUG.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 E MXO 15 S CCY 10 SSE FRM 15 NW ULM 15 NW ANE 15 NNE LUM
10 E MFI 15 E SBM 20 NNW MKG 10 NW FPK 10 NW JXN JYM 10 SSE SBN
10 NNE LAF 15 E PNT 15 E MXO.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 NNE RFD 25 SSW PDC 20 S AUM AEL 15 SSW RGK 30 E VOK
30 NE MKE 40 WNW LWA 15 ESE UGN 15 NNE RFD.



...NORTHERN PLAINS/UPPER MIDWEST SOUTHEASTWARD THROUGH THE OH
VALLEY...

...MDT RISK OF EXCESSIVE RAINS FOR PORTIONS OF SE MN..NE IA..SRN
WI AND EXTREME NRN IL...

A FAIRLY SIGNIFICANT HEAVY RAIN EVENT WILL LIKELY UNFOLD ACRS
PARTS OF THE UPPER MIDWEST WITH POTNL FOR FLASH FLOODING
ESPECIALLY LATE FRI INTO FRI NIGHT.  A WARM FRONT IS EXPECTED TO
RETURN NWD IN ADVANCE OF A LOW PRES SYSTEM THAT WILL PUSH EWD ACRS
THE ERN DAKOTAS.  THE LOW IS EXPECTED TO PROVIDE STG MSTR
TRANSPORT INTO AND NORTH OF THE BNDRY WITH PWS FCST TO INCREASE TO
BETWEEN 2 TO 2.25 INCHES.  FORECAST LIS ALONG AND SOUTH OF THE
FRONT ARE FCST TO INCREASE TO BETWEEN -8 TO -10 DURING PEAK
HEATING WHICH SHOULD ALLOW FOR RAPID EXPANSION OF CONVECTION ONCE
CAP IS BROKEN. PATRN WILL GENLY BE SUPPORTIVE OF CELL TRAINING
WITH MID/UPR FLOW GENLY PARALLEL TO THE SFC FRONT.  THUS..POTNL
WILL EXIST FOR RATHER WIDESPREAD 2 TO 3+" RAINS WITH LOCAL AMOUNTS
UP TO 6 INCHES.  GENL TRENDS OF THE LAST FEW MODEL CYCLES HAVE
SHOWN A SUBTLE SHIFT NWD TO THE MAIN PCPN AXIS.  IN THE CASE OF
THE GFS...IT IS A MUCH FARTHER N SOLN AND APPEARS A BIT OF AN
OUTLIER SOLN AT THIS TIME.  MOST OF THE 00Z HI RES RUNS..REMAIN ON
THE SRN SIDE OF THE GLOBAL GUIDANCE AND ARE GENERALLY
PREFERRED..WITH THE WRF ARW AND NAM CONEST GIVEN MORE WEIGHT.
OVERALL GIVEN THE SLIGHT NWD TRENDS IN THE MODELS...MANUAL QPF
HAVE SHIFTED THE HEAVIER QPF AXIS SLIGHTLY NWD FROM CONTINUITY.
STILL WITH THE MAIN HEAVY RAIN AXIS FORECAST TO OCCUR OVER AREAS
THAT HAVE EXPERIENCED SOME RECENT HEAVY RAINS...HAVE HIGHLIGHTED
MUCH OF SE MN..NE IA INTO SRN WI AND EXTREME NRN IL IN A MODERATE
RISK OF EXCESSIVE RAINS.  ADDITIONAL STORMS ARE LIKELY TO CONTINUE
TO SPREAD SEWD FROM EARLY MORNING COMPLEX ACRS PARTS OF THE
MIDWEST INTO THE OH VALLEY TOWARD THE CNTL APLCNS THIS AFTN.
WHILE NOT LIKELY TO PRODUCE WIDESPREAD HEAVY RAINS..NONE THE
LESS..STG INSTABILITY AND MDTLY HI MSTR COULD LEAD TO LOCALLY
HEAVY RAINS EWD INTO PARTS OF THE CNTL APLCNS FRI/FRI NIGHT AND
ISOLD FLASH FLOODING CAN NOT BE RULED OUT AND THEREFORE THIS AREA
HAS BEEN CONTAINED IN A MARGINAL RISK.    A WEAK 7H WAVE MOVING
ACROSS SOUTHERN CANADA AND THE DAKOTAS WILL SUPPORT AN AREA OF
CONVECTION AHEAD OF AN ASSOCD COLD FRONT FRI AFTN.  STG
INSTABILITY DVLPG AHEAD OF THE FRONT THRU NRN MN WILL LIKELY
SUPPORT SOME INTENSE CONVECTION..BUT CURRENT THINKING IS THAT WITH
DEEPER MSTR FOCUSING TO THE SOUTHEAST...THE VERY INTENSE AMOUNTS
FORECAST BY THE GFS APPEAR OVERDONE..BUT STILL COULD SEE LOCALLY
HEAVY DOWNPOURS FROM THE ERN DAKOTAS INTO NWRN MN GIVEN EXPECTED
HIGH INSTABILITIES FRI AFTN/EVENING.

...4 CORNERS REGION...

SOME SUBTLE DRYING IS EXPECTED THROUGH PARTS OF THE GT BASIN AS
WLYS TAKE A SLIGHT DIP SWD ACRS THE WEST COAST..HOWEVER FOR MUCH
OF THE 4 CORNERS REGION...PATRN WILL REMAIN MUCH THE SAME WITH
AREA WELL ENTRENCHED IN MONSOONAL CIRCULATION AROUND THE WESTERN
PERIPHERY THE STRONG UPPER RIDGE SITUATED OVER THE CNTL PLAINS/MID
MS VALLEY.  THE HIGH MSTR COMBINED WITH DAYTIME HEATING AND EMBDD
WEAK VORTS/MCVS ROTATING WITHIN THE WEAK ANTICYCLONIC CIRCULATION
WILL SUPPORT SOME LOCALLY HEAVY RAINFALL ACCUMULATIONS ALONG WITH
THE POTNL FOR FLASH FLOODING ESPECIALLY ACRS BURN SCAR AREAS AND
NEAR STEEPER TERRAIN.

SULLIVAN
$$





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