Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 101330
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
929 AM EDT THU AUG 10 2017

...VALID 15Z THU AUG 10 2017 - 12Z FRI AUG 11 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 N AAT 50 S AAT 25 NNE RDD 30 W SIY 25 NE MFR 30 NE LMT
10 N AAT.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 S 20V 40 WSW LAR 20 SSE BRX 40 NW AKO 25 NE AKO 30 SE IML
25 S HLC 20 S SLN 20 NE UKL 40 N SGF 25 SE HRO 10 NW MWT
25 N PRX 10 ESE SPS 25 E PVW 30 WSW TCC 20 ENE ALS 10 S 20V.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 NNE DTN 40 SW PBF 40 NE GWO MSL 30 NNE MDQ 35 NNW CSV
30 N SME 55 ENE LEX 15 NE 3I2 20 E CRW 20 NNW TRI 1A5 15 ENE FFC
10 SSE LSF 20 NW ECP 20 ENE BFM NBG 10 SW LFT 20 N POE
25 NNE DTN.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 SW CYQT 10 E CYTJ 45 NNW CYLD 55 SE CYLD 20 NW CWNL
15 WSW SJX LDM ETB 10 NW ATW 15 SSE RHI 25 S IWD 25 WNW HYR TWM
GNA.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 NE PBI 20 ESE PMP 20 NW HWO 35 WNW PBI 25 WNW VRB COF
25 E COF 30 NE SUA 25 NE PBI.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 SSE LGU 30 SSE U78 40 WNW BPI 35 ESE JAC 35 SSE P60
25 SW COD 45 S COD 30 NW RIW 35 NE BPI 10 WSW BPI 40 N FIR
10 SSE FIR 45 NNW VEL 35 NNE VEL 10 S VEL 45 N PUC 35 E SLC
20 E HIF 10 SSE LGU.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 NNW SAD 30 NE FHU 15 SE FHU 75 SW OLS 125 SSE YUM 55 SSE IPL
20 WSW BLH 60 SE EED 25 S PRC 20 WNW SOW 10 ESE SJN 50 S GNT
60 SSW ABQ 30 NNE TCS 40 W TCS 40 NNE SAD 10 NNW SAD.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 ENE LHX 20 WSW LIC 40 SSE AKO 55 NW GCK 15 SSE DDC
20 ESE PTT 40 S EMP 10 NW VBT RKR 45 SE MLC PVJ 10 E LAW
30 WNW LTS 10 E BGD 25 SSW EHA 20 N SPD 20 ENE LHX.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 E JAN 35 ESE JAN 25 W PIB 20 N MCB 15 NNE HEZ 25 NNE ESF
30 ENE IER 30 W MLU 25 SW GLH 35 N HKS 30 E JAN.


...CENTRAL/SOUTHERN PLAINS...

A SERIES OF IMPULSES MOVING ALONG THE SRN EDGE OF THE WESTERLIES
OUT FROM THE WEST TO THE CENTRAL ROCKIES AND S-CENTRAL PLAINS
SHOULD SUPPORT A PRECIP MAX FROM THE VICINITY OF SOUTHEAST WY/ERN
CO SOUTHEASTWARD TOWARD THE TX/OK PANHANDLE AND ACROSS SRN KS/SW
MO AND OK. CONVECTION WILL BE SUPPORTED BY FAVORABLE UPPER
DIFFLUENCE NEAR A FRONTAL ZONE THAT WILL ACT TO POOL MOIST INFLOW.
THE 04 UTC NBM AND 00 UTC NAM CONEST ALLOW MODERATE TO HEAVY
PRECIP. THE 00Z WRF ARW/NMMB/NSSL WRF/CANADIAN GLOBAL MODELS ALL
SHOW A BAND OF 3-5 INCH RAINS TONIGHT ACROSS PORTIONS OF SOUTHEAST
KS TO NORTHEAST OK.  THIS WARRANTS A SLIGHT EXCESSIVE RAINFALL
THREAT FOR ASSOCIATED RUNOFF ISSUE POTENTIAL GIVEN MODEL SUPPORT
INCLUDING SOME LOCALLY HEAVY RAINFALL POTENTIAL.

...CENTRAL GULF COAST...SOUTHEAST...TN VALLEY INTO THE UPPER OH
VALLEY...

A WAVY SURFACE FRONTAL BOUNDARY STRETCHING FROM TX AND THE GULF
COAST TO OFF THE SOUTHEAST COAST HAS BEGIN TO PUSH NORTH. PW
VALUES WILL REMAIN ABOVE AVERAGE ALONG/SOUTH OF THIS BOUNDARY TO
SUPPORT ADDITIONAL WIDESPREAD CONVECTION.

OVER NORTHERN LA SLOW MOVING CONVECTION IN THE DEEPLY MOIST
AIRMASS (JACKSON MS 12Z SOUNDING CONTAINED 2 INCHES OF
PRECIPITABLE WATER WITH LOW SHEAR SOUTHWEST FLOW 1000-700 MB) MAY
REDEVELOP LATER AS THE MOISTURE REMAINS IN PLACE AND POCKETS OF
850-700 MB CONVERGENCE PRODUCE LIFT AHEAD OF THE APPROACHING 700
MB TROUGH.

IN RESPONSE TO THE AMPLIFYING AREA OF HEIGHT FALLS OVER THE UPPER
MS VALLEY/UPPER LAKES REGION...ABOVE AVERAGE PW VALUES WILL ALSO
BEGIN TO PUSH NORTHEASTWARD TO THE WEST OF THE APPALACHIANS
THROUGH ERN TN/KY TO THE UPPER OH VALLEY REGION...SUPPORTING
LOCALLY HEAVY PRECIP ACROSS THESE AREAS. THIS WARRANTS A MARGINAL
EXCESSIVE RAINFALL THREAT FOR ASSOCIATED RUNOFF ISSUES GIVEN
AVAILABLE MOISTURE.

...UPPER MS VALLEY/GREAT LAKES...

GUIDANCE REMAINS FAIRLY WELL CLUSTERED WITH DEPICTION OF WELL
DEFINED HEIGHT FALLS FROM THE NRN PLAINS TO THE UPPER MS
VALLEY/GREAT LAKES DAY 1. WHILE THERE ARE A LOT DETAIL QPF DETAIL
DIFFERENCES AMONG THE MODELS...CONSENSUS IS FOR THE POTENTIAL FOR
MODERATE TO LOCALLY HEAVY PRECIP TOTALS IN THE REGION OF UPPER
DIFFLUENCE AHEAD OF THESE HEIGHT FALLS FROM THE UPPER MS VALLEY
INTO THE LAKES AND SOUTHWARD INTO THE MID MS VALLEY WITH APPROACH
OF A WAVY FRONTAL SYSTEM. WHILE PRECIPITATION AREAS SHOULD BE
GENERALLY PROGRESSIVE AHEAD OF THESE HEIGHT FALLS...THERE MAY BE
ENHANCED TOTALS IN THE COMMA HEAD DEFORMATION BAND PIVOTING OVER
THE UPPER LAKES.  PRECIP MAY ALSO HAVE UVV ENHANCEMENT FROM
NORTHEAST FLOW OFF OF LAKE SUPERIOR AND FAVORABLE RIGHT ENTRANCE
REGION UPPER JET LIFT. THIS WARRANTS A MARGINAL EXCESSIVE RAINFALL
THREAT FOR ASSOCIATED RUNOFF ISSUE POTENTIAL.

...SOUTHEAST FL...

AN INVERTED SFC TROUGH AND 850 MB CIRCULATION HAS FORMED OFF THE
SOUTHEAST FL COAST...WITH SHOWERS/EMBEDDED STORMS IN THE COASTAL
WATERS TO THE SHORELINE.  THE MODELS INDICATE THE PERSISTENCE OF
THE 700 MB TROUGH TODAY WITH PERIODS OF CONVERGENCE.
ADDITIONALLY...HIGH AVAILABLE MOISTURE IS FORECAST TO BE IN
PLACE...WITH FORECAST PRECIPITABLE WATER AMOUNTS OF 2-2.25 INCHES.
 THE SHOWERS AS A RESULT OF PERIODS OF LIFT FROM 700 MB
CONVERGENCE AND HIGH AVAILABLE MOISTURE COULD PRODUCE HEAVY
SHOWERS.  THE AREA IS LISTED AS MARGINAL DUE TO THE HIGH FLASH
FLOOD GUIDANCE VALUES OF 4-5 INCHES OF RAIN IN 6 HOURS.  MOST
MODELS SHOW 1-3 INCHES WITH 3-4 INCH MAXIMA IN THE NSSL WRF TODAY.

...NRN CA/ADJACENT SOUTHERN OR/NORTHEAST UT TO WESTERN WY AND
SOUTHERN AZ/NM/SOUTHEAST CA...

A REX BLOCK THAT HAS BEEN OFF THE PAC NW/NRN CA THE PAST FEW DAYS
WILL BEGIN TO BREAK DOWN AS NE PAC HEIGHT FALLS APPROACH THE
COAST. SCATTERED DIURNAL CONVECTION REMAINS LIKELY THIS PERIOD IN
THE VICINITY OF AN UPPER LOW EASTWARD FROM NRN CA INTO THE GREAT
BASIN. PW VALUES REMAIN ABOVE AVERAGE ACROSS THESE
REGIONS...SUPPORTING POTENTIAL FOR ISOLATED MODERATE TO HEAVY
TOTALS. GUIDANCE HAS BEEN GENERALLY UNDER FORECASTING PCPN
COVERAGE AND LOCAL POTENTIAL. THIS WARRANTS A MARGINAL EXCESSIVE
RAINFALL THREAT FOR ASSOCIATED RUNOFF ISSUE POTENTIAL. ALSO
INCLUDED PORTIONS OF SERN AZ/SWRN NM/SOUTHEAST CA AS VORT ENERGY
FROM LAST NIGHT`S CONVECTIVE COMPLEX NEAR THE MEXICO/US BORDER
DRIFTS WEST AND DEEPENED MOISTURE ROTATES INTO SOUTHERN
AZ/SOUTHEAST CA..WITH FORECAST PW VALUES TO 2 INCHES.

PETERSEN/SCHICHTEL
$$





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