Quantitative Precipitation Forecast
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FOUS30 KWBC 291429
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1028 AM EDT FRI JUL 29 2016

...VALID 15Z FRI JUL 29 2016 - 12Z SAT JUL 30 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 W PWA 15 ESE SPD 10 SW PUB 35 W AFF 10 SSW BJC 30 ENE DEN
GLD 25 SSW SLN 35 WSW TBN 30 SSW FAM 35 SSE FAM 25 SSW OWB
20 SE OWB 30 SW FTK 35 SSW FFT 30 SSE LEX 25 ESE JKL 20 W 6V3
15 S VJI 25 S TRI 20 E TYS 25 SW TYS 35 NW MDQ 25 NW MSL
35 E PBF 20 NW LLQ 25 NNW TXK 25 ENE AQR 15 W PWA.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 SSE RYV 10 NW BIV VLL 15 SE CXPT 20 WNW 4I3 15 NNE DAY
10 NW LAF IOW ALO 20 NNW PDC 10 SSE RYV.


1500 UTC UPDATE

CHANGES TO THE PREVIOUS EXCESSIVE RAINFALL POTENTIAL OUTLOOK WERE
TO REMOVE THE SEE TEXT OVER LONG ISLAND INTO SOUTHERN NEW ENGLAND.
 MAX RAINFALL RATES ARE GENERALLY IN THE .50"+ RANGE FOR 1 HOUR
ACROSS LONG ISLAND AND FAR SOUTHERN NEW ENGLAND.  AT THE
MOMENT---WITH THIS SYSTEM FORECAST TO REMAIN PROGRESSIVE AND FFG
VALUES HIGH---DO NOT BELIEVE THERE WILL BE ANY RUNOFF ISSUES FROM
THE MODERATE TO HEAVY RAINFALL RATES.

ACROSS SOUTHERN KY INTO CENTRAL TO EASTERN TN---THE EASTERN END OF
THE PREVIOUS SLIGHT RISK AREA OVER WESTERN TN AND FAR WESTERN KY
WAS EXPANDED EASTWARD TO INCLUDE ALL OF SOUTHERN KY AND MOST OF
THE REMAINING PORTIONS OF TN. THIS WAS TO ACCOUNT FOR LOWERED FFG
VALUES FROM RECENT RAINS AND TO COVER THE SPREAD IN MODEL QPF THAT
EXTEND HEAVY PRECIP POTENTIAL EASTWARD ACROSS THESE AREAS THIS
PERIOD.

ORAVEC


PREVIOUS DISCUSSION

...PLAINS TO THE MID/LOWER MISSISSIPPI VALLEY...

WITH AN ESTABLISHED EAST-WEST BAROCLINIC ZONE AND NORTHWEST FLOW
ALOFT...THE PATTERN FAVORS FAIRLY WIDESPREAD PRECIPITATION FROM
EASTERN CO/NM ACROSS KS/OK INTO MO/AR. ONE OF THE HIGHER
CONFIDENCE MODEL QPF SIGNALS IS ACROSS SOUTHERN KS / NORTHERN OK
HEADING EASTWARD INTO MO/AR...WHERE IT APPEARS THAT AN ORGANIZED
MCS COULD TRACK THIS MORNING AS CONVECTION GROWS UPSCALE OUT OF
COLORADO AND WESTERN KANSAS. IF THIS OCCURS...THE RESULTING
OUTFLOW AND PERHAPS MCV ALOFT COULD LEAD TO ORGANIZATION ALONG AN
ELONGATED AXIS EXTENDING FROM ARKANSAS INTO SOUTHERN OKLAHOMA BY
AFTERNOON/EVENING. BACK NORTH AND WEST IT IS POSSIBLE THAT
ADDITIONAL CLUSTERS OF STORMS WOULD FORM IN THE AFTERNOON FROM
COLORADO TO THE TEXAS PANHANDLE...GIVEN AMPLE RECOVERY OF
INSTABILITY WITHIN AN OTHERWISE UNCHANGED SYNOPTIC PATTERN. FLASH
FLOOD POTENTIAL DOES NOT APPEAR PARTICULARLY FOCUSED...BUT WILL
EXIST AT TIMES...WHEREVER CELL MERGERS OCCUR...AND WHERE FLASH
FLOOD GUIDANCE VALUES HAVE BEEN REDUCED LOCALLY DUE TO RECENT
RAINS...ESPECIALLY PARTS OF EASTERN CO / WESTERN KS AND IN THE
OZARKS.


...SOUTHERN GREAT LAKES / PARTS OF IA/WI/IL/IN/OH/MI...

A LARGE SCALE WEAKNESS / TROUGH REMAINS ANCHORED FROM THE GREAT
LAKES TO THE LOWER MISSISSIPPI VALLEY AS SHORTWAVES ROTATE THROUGH
IT. THE CENTER OF BETTER DEFINED VORTICITY HAS REMAINED IN THE
VICINITY OF THE WESTERN AND SOUTHERN GREAT LAKES OVER THE PAST
DAY...AND WILL CONTINUE TO PRODUCE A LITTLE GREATER COVERAGE OF
DIURNALLY ENHANCED CONVECTION TODAY OVER PARTS OF
IA/WI/IL/IN/OH/MI. PRECIPITABLE WATER VALUES ARE SOMEWHAT MODEST
IN THIS REGION...BUT MAY PROVE SUFFICIENT FOR HEAVY
RAINFALL...PEAKING AROUND 1.50 INCHES DURING ACTIVE CONVECTION.
WEAK STEERING FLOW...WITH MEAN 0-6 KM WINDS NEAR ZERO...ARE A
CAUSE FOR CONCERN...AND FLASH FLOOD GUIDANCE VALUES ARE LOCALLY
REDUCED ACROSS CHICAGO-LAND.


...CENTRAL FLORIDA...

FLOW BECOMES A BIT MORE SOUTHERLY TODAY AND A SLUG OF DEEPER
MOISTURE OFF THE SOUTHWEST COAST WAS POISED TO MOVE TOWARD CENTRAL
FLORIDA...WITH PRECIPITABLE WATER VALUES RISING JUST ABOVE 2
INCHES THIS AFTERNOON. THIS SHOULD PROVE FAVORABLE FOR GREATER
RAINFALL PRODUCTION RELATIVE TO RECENT DAYS...AS SEA BREEZES WILL
MEET IN THE MIDDLE OF THE PENINSULA AND FIND A SOUPIER AIRMASS
WAITING THERE. CELL MOTIONS ARE PREDICTED NEAR ZERO...AND WHEN
COMBINED WITH A STRIPE OF HEAVY QPF FROM THE WRF-ARW AND
NAM...RAISES SOME CONCERN OVER FLASH FLOOD POTENTIAL...MAINLY IN
THE POPULATION CENTERS ALONG HIGHWAYS 4 AND 75 BETWEEN GAINESVILLE
AND SEBRING. THE LIMITING FACTOR WOULD APPEAR TO BE A LACK OF
SUSTAINED INFLOW AT ANY GIVEN LEVEL...SUCH THAT ALTHOUGH STORMS
MAY BE STATIONARY THEY MAY NOT PERSIST LONG ENOUGH TO PRODUCE
EXTREME RAIN TOTALS. THE VERY MOIST ENVIRONMENT...HOWEVER...MAY
ALLOW FOR QUICK ACCUMULATIONS OF 2-4 INCHES IN ISOLATED SPOTS.

BURKE
$$





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