Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 290807
QPFERD

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

...VALID 12Z 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 CIR 50 SW HOP 35 ENE OLV 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.


...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.


...SOUTHERN NEW ENGLAND...

MORE SIGNIFICANT...WARM-SECTOR-STYLE...INSTABILITY MAY REMAIN JUST
OFFSHORE...BUT ORGANIZED ASCENT WITHIN A DEEPLY SATURATED AIRMASS
IS LIKELY TO YIELD AT LEAST MODERATE PRECIPITATION...ESPECIALLY
FROM LONG ISLAND TO CAPE COD. THE HEAVIEST PRECIPITATION IS
EXPECTED FROM EARLY MORNING THROUGH EARLY AFTERNOON...WHEN AREAL
AVERAGE AMOUNTS GREATER THAN ONE INCH ARE FORECAST NEAR THE COAST.
RAIN RATES APPROACHING ONE INCH PER HOUR HAD BEEN NOTED OVERNIGHT
IN PARTS OF PA/MD...AND COULD CAUSE SOME RUNOFF
ISSUES...PARTICULARLY IN THE URBAN AREAS OF SOUTHERN NEW ENGLAND.


...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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