Quantitative Precipitation Forecast
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000
FOUS30 KWBC 041416
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1015 AM EDT TUE AUG 04 2015

...VALID 15Z TUE AUG 04 2015 - 12Z WED AUG 05 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 NW HLC 30 NW HLC 20 SSE MCK 10 WNW MCK 25 NNW MCK 30 N MCK
20 SSE LBF 20 SE LBF 25 ESE LBF 10 NNW LXN 20 ENE LXN EAR
15 W HSI 15 SE HSI 25 WNW HJH 35 SW FNB 30 NE MKC 15 NE DMO AIZ
15 NNE SGF 10 SE JLN 20 NW GMJ 20 SSW BVO 20 WSW WLD 10 N HYS
20 NW HLC.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
55 S JDN 20 E JDN 35 S OLF 10 NE GDV 30 SE BHK 40 SSE 2WX
25 E RCA 30 SE RAP 30 NW IEN 35 NNW CDR 30 SSW CUT 35 SW CUT
50 WSW CUT 20 N GCC 55 S JDN.


1500 UTC UPDATE

CHANGES TO THE PREVIOUS EXCESSIVE RAINFALL POTENTIAL OUTLOOK WERE
TO EXTEND THE SLIGHT RISK AREA STRETCHING FROM SOUTH CENTRAL NE
INTO EASTERN KS AND SOUTHWEST MO TO THE NORTHEAST TO COVER  AREAS
OF FAR SOUTHEAST NE AND NORTHERN MO WHERE CONVECTION IS CURRENTLY
SLOW MOVING AND TRAINING IN A WEST TO EASTERLY DIRECTION TO THE
NORTH OF THE STATIONARY FRONTAL BOUNDARY STRETCHING FROM THE
CENTRAL PLAINS INTO THE MID MS VALLEY.  THE HI RES GUIDANCE IS NOT
HANDLING THIS CONVECTION WELL--WITH ALL SHOWING THIS ACTIVITY
WEAKENING BY THIS TIME.  THIS VERY WELL MAY STILL BE THE
TREND--BUT DELAYED FOR A FEW HOURS.  IN AREAS OF TRAINING---2"+
AMOUNTS IN AN HOUR POSSIBLE.  SEE WPC MPD # 0420 VALID UNTIL 1500
UTC FOR FURTHER INFORMATION.  THIS MPD MAY BE UPDATED SHORTLY IF
CONVECTION CONTINUES.

ELSEWHERE---NO CHANGES MADE TO THE OTHER AREAS OF CONCERN OVER THE
NORTHERN PLAINS OR THE LOWER NC COAST.

ORAVEC

PREVIOUS DISCUSSION

...NORTHERN ROCKIES/CENTRAL PLAINS/MID MS VALLEY...

MOISTURE AND INSTABILITY NORTH OF A STATIONARY FRONT STRETCHING
FROM THE NORTHERN ROCKIES THROUGH THE CENTRAL PLAINS INTO THE MID
MS VALLEY WILL FUEL CONVECTION THAT COULD PRODUCE HEAVY TO
EXCESSIVE RAINFALL DURING DAY 1.

IN THE NEAR TERM...THE THREAT FOR FLASH FLOODING IS FOCUSED NORTH
OF A STATIONARY FRONT EXTENDING FROM THE NORTHERN ROCKIES INTO THE
MID MS VALLEY.  STRONG INSTABILITY AND PRECIPITABLE WATER VALUES
NEAR 1.30 INCHES ON THE NOSE OF A LOW LEVEL SOUTHEAST INFLOW WILL
FEED CLUSTERS OF CONVECTION ALONG THE LENGTH OF THE AXIS...WHICH
COULD PRODUCE LOCAL 2+ INCH RAINFALL AMOUNTS. THE BEST INSTABILITY
SHOULD BE EXHAUSTED BY 04/12Z ACROSS PORTIONS OF THE NORTHERN
ROCKIES AND CENTRAL PLAINS...BUT COULD BE ONGOING ACROSS THE MD MS
VALLEY THROUGH THAT TIME.

ACROSS MT/SD/NE...THE MOIST INFLOW CONTINUES THROUGH THE MID TO
LATE AFTERNOON...AND MODEL SOUNDINGS SHOWED STRONG INSTABILITY AND
PRECIPITABLE WATER VALUES NEAR 1.50 INCHES DURING THIS TIME
PERIOD. CLUSTERS OF CONVECTION NORTH OF THE FRONT COULD SLOW OR
EVEN BACKBUILD ACROSS SD/NE AS DOWNWIND CORFIDI VECTORS DROP BELOW
10 KNOTS. LOCAL 1.00 INCH QPF AMOUNTS WERE PLACED ALONG THE FRONT
FROM WESTERN SD THROUGH SOUTH CENTRAL NE...BUT LOCALLY HIGHER
AMOUNTS ARE POSSIBLE GIVEN THE INSTABILITY AND MOISTURE PROFILES.
SOME HIGH RESOLUTION GUIDANCE (SUCH AS THE 00Z WRF
ARW/NMMB AND 00Z NAM CONEST) SUGGEST 2.00 INCH AMOUNTS ARE
POSSIBLE...ESPECIALLY FROM SOUTHEAST MT ACROSS WESTERN SD. GIVEN
THE MOISTURE AND INSTABILITY IN PLACE...AND THE POTENTIAL FOR
HIGHER QPF AMOUNTS PER THE HIGH RESOLUTION GUIDANCE...A SLIGHT
RISK AREA WAS PLACED OVER PORTIONS OF SOUTHEAST MT INTO NORTHEAST
WY AND WESTERN SD.

FURTHER SOUTHEAST...ONGOING CONVECTION ACROSS NORTHERN MOS AND
EASTERN NE SHOULD START TO WEAKENING TOWARD 04/12Z...AS THE
REMAINING MUCAPE IS EXHAUSTED. THE ACTIVITY COULD PERSIST PAST
THIS POINT...BUT THE MAIN FLASH FLOOD THREAT SHOULD BE CONFINED TO
12Z OR SO. HIGH RESOLUTION GUIDANCE...SUCH AS THE 00Z WRF
ARW/NMMB...SUGGEST THAT THE THREAT COULD LAST A BIT LONGER...BUT
HIS WILL BE COVERED BY A SLIGHT RISK FOR LATER ACTIVITY.

OTHERWISE..THERE IS A MULTI MODEL SIGNAL FOR AN MCS TO DEVELOP
ACROSS EASTERN KS INTO WESTERN MO DURING THE SECOND HALF OF THE
PERIOD. THE LATEST WRF SIMULATED SATELLITE IMAGERY SUGGESTS THE
DEVELOPMENT OCCURS OVER EASTERN KS AFTER 05/03Z AND PEAKS NEAR
05/06Z OVER WEST CENTRAL MO...AS STRONG LOW LEVEL MOISTURE FLUX IS
TRANSPORTED ION THE NOSE OF A LOW LEVEL JET ACROSS EASTERN KS. THE
00Z NAM IS ALONE WITH A MORE NORTHERLY DEVELOPMENT OF THE MCS
ACROSS NE...WHILE THE REMAINDER OF THE 00Z REGIONAL/GLOBAL
GUIDANCE...AS WELL AS MOST OF THE HIGH RESOLUTION
GUIDANCE...POINTS TOWARD KS/MO. AN AREA OF 1.25 TO 1.50 INCHES OF
QPF WAS PLACED OVER THIS REGION...BUT LOCAL 3.00 INCHES AMOUNTS
ARE POSSIBLE GIVEN THE POTENTIAL FOR HIGH RAINFALL RATES. A SLIGHT
RISK AREA WILL BE RETAINED OVER PORTIONS OF KS/MO FOR THE FLASH
FLOOD THREAT.


...MID ATLANTIC...

DEEP MOISTURE STREAMING ALONG A SURFACE BOUNDARY BECOMES FOCUSED
BY THE PASSAGE OF A SURFACE WAVE ON THE FRONT...RESULTING IN THE
DEVELOPMENT OF CONVECTION WITH HEAVY TO POSSIBLY EXCESSIVE
RAINFALL NEAR THE NC/SC COAST.

CONVECTION ALONG THE NC/SC COASTS HAS INCREASED IN INTENSITY EARLY
THIS MORNING...IN RESPONSE TO BETTER LOW LEVEL CONVERGENCE ALONG
THE SC COAST AND PRECIPITABLE WATER VALUES NEARING 2.25 INCHES.
THE LOW LEVEL SOUTHEAST INFLOW TRANSPORTS INSTABILITY ONSHORE
ACROSS THE REGION THIS MORNING...AND HIGH RESOLUTION GUIDANCE
SUGGESTS THAT LOCAL 2 TO 3 INCH AMOUNTS ARE POSSIBLE THROUGH
04/12Z. THIS AREA WILL NEED TO BE COVERED BY  SEE TEXT...MAINLY
FOR THIS MORNING...TO ACCOUNT FOR THE CONVECTION IN THE DEEP
TROPICAL AIRMASS.

HAYES
$$




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