Quantitative Precipitation Forecast
Issued by NWS

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QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
228 AM EST THU JAN 12 2017

...VALID 12Z THU JAN 12 2017 - 12Z FRI JAN 13 2017...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 WSW AGC 25 E ZZV LHQ OSU MNN 20 WSW CLE 20 WNW HZY
20 SE CWPS 10 NW ROC GTB 25 WSW SLK 25 NW GFL 20 WNW SCH
35 S UCA 15 SSE ITH 30 SSW ELM 20 N UNV 10 W IDI 10 WSW AGC.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
40 SW VBG 20 ENE SMX 15 N 3A6 30 NE ONT 10 NNW PSP 30 ENE RNM
25 SSE CZZ 90 S MMTJ.

MARGINAL RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
VIS 25 NNE MCE 40 ESE MHR 50 SSW TVL 40 SW MMH 45 ENE VIS
35 NW IYK 35 ENE BFL VIS.


...CENTRAL/SOUTHERN CALIFORNIA...

A RATHER STRONG UPPER LOW WILL EVOLVE OVER NORTHERN/CENTRAL CA
THURSDAY INTO EARLY FRIDAY AND SHOULD DRIVE AN AXIS OF MODERATE TO
HEAVY RAINFALL FOR THE FOOTHILLS OF CENTRAL/SOUTHERN SIERRA-NEVADA
AND ALSO DOWN INTO THE SOUTHERN CA COASTAL RANGES. THE AXIS OF
MOST ANOMALOUS MOISTURE AND ONSHORE FLOW SHOULD TEND TO FAVOR THE
UPSLOPE AREAS OF ESPECIALLY THE SAN BERNADINO AND SAN GABRIEL
MOUNTAINS WHERE THERE WILL BE LOCALIZED CONCERN OVER THE BURN SCAR
AREAS. EXPECT AS MUCH AS 1 TO 2 INCHES OF RAIN HERE AND ALSO BACK
UP ACROSS SOME OF THE FOOTHILLS OF THE AFOREMENTIONED
SIERRA-NEVADA. THESE RAINS WILL PROMOTE SOME ADDITIONAL RUNOFF
CONCERNS...INCLUDING POTENTIAL MUDSLIDES AND DEBRIS FLOWS NEAR THE
BURN SCAR AREAS.

...OHIO/PENNSYLVANIA/NEW YORK...

A SHORTWAVE TROUGH CROSSING THE GREAT LAKES REGION WILL DRIVE
MULTIPLE WAVES OF LOW PRESSURE NORTHEAST ACROSS THE OH VALLEY AND
LOWER GREAT LAKES REGION ON THURSDAY WHICH WILL DRIVE AN AXIS OF
MODERATE TO HEAVY SHOWERS AS THEY ENCOUNTER A FAVORABLY MOIST AND
EVEN VERY MODESTLY UNSTABLE AIRMASS POOLED JUST AHEAD OF THE
ATTENDANT COLD FRONT GIVEN THE SOUTHWEST LOW LEVEL JET OF 50+ KTS
SURGING UP THROUGH THE OH VALLEY. RELATIVELY FAVORABLE UPPER JET
SUPPORT WILL BE IN PLACE AND COINCIDING WITH THE MODESTLY
FAVORABLE THERMODYNAMIC ENVIRONMENT FOR SOME HEAVIER RAINFALL
RATES. IN FACT...THE PW VALUES WILL BE 2.5 TO 3.0+ STANDARD
DEVIATIONS ABOVE NORMAL AHEAD OF THE COLD FRONT. THE HIRES
GUIDANCE LED ESPECIALLY BY THE ARW/NMMB AND THE HRRR ALL SUGGEST
SOME POTENTIAL FOR SOME WSW/ENE ORIENTED TRAINING OF CONVECTION
JUST AHEAD OF THE COLD FRONT...AND SUGGEST SOME 1 TO 2 INCH
RAINFALL POTENTIAL ACROSS THE UPPER OH VALLEY AND INTO NORTHWEST
PA AND WESTERN NY. THESE RAINS WILL BE FALLING OVER WET/SATURATED
GROUNDS GIVEN RECENT SNOWMELT...AND THUS THERE WILL BE SOME
CONCERN FOR RUNOFF PROBLEMS AND EVEN ISOLATED FLASH FLOODING.

ORRISON

$$




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