Quantitative Precipitation Forecast
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FOUS30 KWBC 071433
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1033 AM EDT TUE JUL 07 2015

...VALID 15Z TUE JUL 07 2015 - 12Z WED JUL 08 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
45 SE MLC 10 W GVT 10 NNW GTU 10 E ERV 45 WSW DRT 55 S 6R6
30 WSW 6R6 35 N 6R6 10 W SWW 15 WSW LTS 20 NE HBR 25 E JWG
10 NNW SWO 15 ESE BVO 35 SW TBN 25 WSW FAM 35 S BMG 15 NW CVG
LUK 10 ENE LUK 45 SE LUK 30 E LEX 25 N SME 15 WSW GLW 15 NE JBR
15 SSE RKR 45 SE MLC.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 E MLC 15 SSE GYI 25 N 05F 20 WNW 6R9 25 NW JCT 20 NNE E29
15 NW SJT 45 NNE ABI 20 NNW SPS 10 W OUN 15 ESE GMJ 15 NW CGI
25 ESE HSB 15 SSW EHR 30 ESE PAH 20 SSE FLP 30 E MLC.


1500 UTC UPDATE

CHANGES TO THE PREVIOUS EXCESSIVE RAINFALL POTENTIAL OUTLOOK WERE
TO EXTEND THE SLIGHT AND MODERATE RISK AREAS EAST NORTHEASTWARD
INTO THE LOWER TO MIDDLE OH RIVER VALLEY TO THE SOUTH OF THE
SURFACE FRONTAL BOUNDARY DROPPING SOUTHEASTWARD.  CONCERNS ARE FOR
TRAINING OF CELLS IN A WEST SOUTHWESTERLY TO EAST NORTHEASTERLY
DIRECTION IN THE AXIS OF MUCH ABOVE AVERAGE PW VALUES ACROSS THESE
AREAS.  ON THE WESTERN EXTENT OF THE PREVIOUS OUTLOOK AREA---THE
RISK AREAS WERE PUSHED TO THE SOUTHEAST GIVEN LATEST RADAR TRENDS.
 THE MCV OVER NORTH CENTRAL TX IS FARTHER TO THE SOUTH THAN
PREVIOUS MODEL FORECASTS.  SOMEWHAT UNCERTAIN AS TO WHETHER
CONVECTION WILL RE-FIRE FARTHER NORTHWARD CLOSER TO THE FRONT
LATER THIS AFTERNOON INTO TONIGHT IN THE WAKE OF THIS MCV---SO THE
NORTHERN EXTENT OF THE OUTLOOK AREAS WAS NOT CHANGED HERE.  PLEASE
SEE WPC`S MESOSCALE PRECIPITATION DISCUSSION #0320 AND #0321 FOR
FURTHER INFORMATION ACROSS THE OUTLOOK AREAS.

OVER THE GREAT BASIN INTO THE CENTRAL TO NORTHERN SIERRA---A SEE
TEXT REGION WAS ADDED FOR THE EXPECTATIONS OF ADDITIONAL
WIDESPREAD SCATTERED CONVECTION FROM THE CENTRAL TO
NORTHERN---ACROSS THE GREAT BASIN AND INTO THE CENTRAL ROCKIES.
PW VALUES EXPECTED TO REMAIN MUCH ABOVE AVERAGE ACROSS THESE
REGIONS---2+ STANDARD DEVIATIONS ABOVE THE MEAN.  UPPER DIFFLUENCE
EXPECTED TO BE VERY WELL DEFINED LATE THIS AFTERNOON TO THE EAST
OF THE CLOSED LOW OFF THE NORTHERN CALIFORNIA COAST AND AHEAD OF
THE UPPER TROF OVER THE GREAT BASIN.  ISOLATED VERY HEAVY TO
EXCESSIVE RAINFALL AMOUNTS POSSIBLE OVER A FAIRLY BROAD REGION
FROM SHORT TERM 1"+ PRECIP TOTALS.

ORAVEC


PREVIOUS DISCUSSION

AGAIN..THE LATEST MODEL RUNS CONTINUE TO ADVERTISE A CONVECTIVELY
ACTIVE FRONT/FRONTAL PASSAGE ALL THE WAY FROM THE SOUTHERN HIGH
PLAINS EAST-NORTHEASTWARD INTO WESTERN NEW ENGLAND THIS
PERIOD..AND ESPECIALLY SO OVER THE SOUTHERN HIGH PLAINS/SOUTHERN
PLAINS..WHERE SOME VERY HEAVY TO EXCESSIVE RAINS ARE EXPECTED.
FROM WESTERN NEW ENGLAND BACK INTO THE MID OH VALLEY..A MORE
PROGRESSIVE PATTERN/CLEANER COLD FRONTAL PASSAGE SHOULD KEEP
RAINFALL AMOUNTS IN THE 0.25-0.50+ INCH RANGE THESE AREAS..AS PER
MUCH OF THE MODEL GUIDANCE..BUT WHERE THE FRONT STALLS FROM THE
MID OH VALLEY SOUTHWESTWARD INTO THE SOUTHERN HIGH PLAINS..THE
POTENTIAL INCREASES FOR HEAVY RAINS..AND AGAIN ESPECIALLY SO IN
THE SOUTHERN HIGH PLAINS/SOUTHERN PLAINS.  HERE..A PERSISTENT AND
MODERATELY STRONG LOW LEVEL JET INTO THE QUASI-STATIONARY FRONTAL
BOUNDARY..THE POOLING OF PWS TO ABOVE 2 INCHES VICINITY OF THE
BOUNDARY..AND WEAK H5 S/WV ENERGY MOVING OUT OF THE HIGH PLAINS
ALONG THE SOUTHERN EDGE OF THE WESTERLIES..WILL BE MORE THAN
ENOUGH TO SUPPORT ORGANIZED AND VERY HEAVY CONVECTION.  FOR THE
MOST PART THE MODEL MASS FIELD AND QPFS ARE IN DECENT AGREEMENT ON
THIS SCENARIO..BUT WPC QPF LEANED TOWARDS AN ARW..NMMB..NSSL WRF
AND GEM REGIONAL BLEND..WITH THE NAM AND OLD ECMWF HIRES QPFS
HAVING THEIR HEAVIER RAINFALL AXES IN OK A BIT TOO FAR NORTH AND
THE GFS SHOWING SOME FEEDBACK PROBLEMS LATER IN THE PERIOD.  AREAL
AVERAGE 1-3+ INCH RAINFALL TOTALS ARE EXPECTED FROM PARTS OF
WESTERN TX NORTHEASTWARD INTO NORTHEASTERN OK..WITH SOME ISOLATED
5+ INCH AMOUNTS POSSIBLE..WHILE SOME 1-2 INCH RAINS ARE LIKELY
FROM NORTHWESTERN AR/SOUTH CENTRAL MO UP INTO THE LOWER OH RIVER
VALLEY.  KEPT THE RATHER LARGE SLIGHT RISK GOING FROM THE SOUTHERN
HIGH PLAINS UP TOWARDS THE LOWER OH VALLEY..WITH A MODERATE RISK
FROM PARTS OF WESTERN TX INTO SOUTHERN/CENTRAL OK.

TERRY

$$




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