Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 160130
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
930 PM EDT WED OCT 15 2014

...VALID 03Z THU OCT 16 2014 - 00Z FRI OCT 17 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 WSW MPO 30 SSW UCA 35 ENE GTB 30 NNW RUT 10 NW EEN WST
45 SSE FOK 60 ESE MJX 25 ENE ACY 10 S PTW 20 WSW MPO.



DEEP LAYERED MOISTURE AHEAD OF A STRONG AND HIGHLY AMPLIFIED MID
LEVEL TROUGH CROSSING THE EASTERN UNITED STATES WILL FEED LOW
TOPPED CONVECTION ACROSS PORTIONS OF THE NORTHERN MID ATLANTIC
INTO NY STATE AND NEW ENGLAND DURING THE EVENING AND OVERNIGHT
HOURS. A 40 KNOT LOW LEVEL SOUTHERLY FLOW WILL CONTINUE TO PUMP
HIGH MOISTURE CONTENT AIR INTO THE REGION AHEAD OF A SURFACE FRONT
EXTENDING FROM WESTERN NY STATE THROUGH THE MID ATLANTIC STATES.
THE LATEST BLENDED TOTAL PRECIPITABLE WATER PRODUCT SHOWED A 1.60
INCH (WHICH IS ABOUT TWO STANDARD DEVIATIONS ABOVE NORMAL)
BULLSEYE OVER CENTRAL NY STATE...WITH ANOTHER ROUND OF MOISTURE
JUST OFF THE SOUTHERN DELMARVA PENINSULA. AS THESE SLUGS OF
MOISTURE MOVE NORTH...THEY WILL FEED SHOWERS AND LOW TOPPED
CONVECTION SPANNING FROM NORTHEAST MD INTO CENTRAL AND NORTHERN NY
STATE.

INSTABILITY MAY END UP BEING THE LIMITING FACTOR WITH RESPECT TO
CONVECTION...BUT 00Z SOUNDINGS FROM WAL AND OKX SHOW BETWEEN 350
AND 700
J/KG OF CAPE. THE LATEST RAP MODEL SOUNDINGS FOR THE REGION SHOWED
MOIST PROFILES THROUGH AT LEAST 16/05Z...SUGGESTING THAT THE
CONVECTION IS DOMINATED BY WARM RAIN PROCESSES. RAINFALL RATES
(BASED ON LOCAL RADAR ESTIMATES) ARE GENERALLY LESS AN AN
INCH...WITH THE HIGHEST RATES ACROSS SOUTHWEST NJ...WHICH APPEAR
TO BE SUPPORTED BY LOCAL MESONET OBSERVATIONS. IT IS POSSIBLE
THAT...DUE TO THE WARM RAIN PROCESSES... THAT THE RADAR ESTIMATES
COULD BE UNDERDONE...ESPECIALLY FROM CENTRAL NJ INTO NORTHERN NY
STATE.

THE LATEST HIGH RESOLUTION GUIDANCE (INCLUDING THE LATEST
RAP...HRRR AND NAM CONEST) ARE RUNNING A BIT BEHIND REALITY...BUT
CLOSE ENOUGH TO SUGGEST THAT 1.00 TO 2.00 INCHES OF QPF SHOULD BE
EXPECTED WITH THE LOW TOPPED CONVECTION THROUGH ABOUT 16/08Z
ACROSS PORTIONS OF NJ/SOUTHEAST NY STATE INTO WESTERN NEW ENGLAND.
BASED ON THE HIGH RESOLUTION GUIDANCE...AND THE CURRENT RADAR
TRENDS...THE SLIGHT RISK AREA WAS ADJUSTED WESTWARD TO INCLUDE
MORE OF EASTERN PA AND CENTRAL AND NORTHERN NY STATE...WHERE SOME
TRAINING IS EXPECTED THROUGH THE LATE EVENING. SINCE RAINFALL
RATES SHOULD REMAIN BELOW 1.50 INCHES IN AN HOUR...IT APPEARS AS
THOUGH MOST FLOODING ISSUES MAY BE MORE ALONG THE LINES OF FLOOD
VS FLASH FLOOD...ESPECIALLY IN URBAN AREAS.

HAYES
$$





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