Quantitative Precipitation Forecast
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306
FOUS30 KWBC 240816
QPFERD

EXCESSIVE RAINFALL DISCUSSION...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
415 AM EDT SUN JUL 24 2016

...VALID 12Z SUN JUL 24 2016 - 12Z MON JUL 25 2016...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 SW DNV 10 W TIP 20 SE C75 25 NNE GYY 10 SSE GRR MBS
25 NNW CFS 15 SE P58 25 SE PHN CXHA 15 NW CLE 15 WNW DKK
10 NNE CWWZ 25 NNW ROC 10 S DSV 20 SSW BFD PIT 15 NW ZZV
10 NE DAY 15 SE DNV 10 SW DNV.


GREAT LAKES/WESTERN NY/NORTHWEST PA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A BATCH OF THUNDERSTORMS ERUPTING IN MN IS UNANIMOUSLY FORECAST BY
THE 00Z MESOSCALE GUIDANCE TO HOLD ON AS THEY TRACK EAST-SOUTHEAST
ACROSS WI AND MI DURING THE DAY SUNDAY, PERHAPS BECOMING MORE
EFFICIENT RAINFALL WISE DURING THE LATE MORNING AND AFTERNOON
HOURS AS THEY TRACK ACROSS MI.  CONVERGENT LOW-LEVEL INFLOW OF
20-40 KTS IS SEEN NEAR THE TRACK OF THESE THUNDERSTORMS ASSOCIATED
WITH A PROGRESSIVE FRONTAL SYSTEM, WHILE MUCAPES CURRENTLY
2000-4000 J/KG SOUTH OF THE SYSTEM SHOULD INCREASE WITH DAYTIME
HEATING.  PRECIPITABLE WATER VALUES ARE EXPECTED TO BE AT OR ABOVE
2" HERE.  PREFERRED GUIDANCE INCLUDED THE 00Z ECMWF, 00Z SPC WRF,
00Z WRF NSSL, 00Z NAM CONEST, 00Z ARW, AND 00Z NMMB.

ACROSS THE NORTHERN MID-ATLANTIC STATES, THE GUIDANCE, MESOSCALE
AND OTHERWISE, SHOWS A GREAT DEAL OF DISPERSION IN THIS REGION
WITHIN THE WARM AIR ADVECTION PATTERN AHEAD OF THE OCCLUDED
FRONTAL SYSTEM.  COMPLICATING MATTERS WOULD BE OUTFLOW BOUNDARIES
FROM THE ACTIVITY MOVING OUT OF IN AS WELL AS ANY MOVING OUT FROM
WHAT IS EXPECTED TO MOVE THROUGH MI.  PREFERRED GUIDANCE HERE WAS
A COMBINATION OF THE 00Z ECMWF, 00Z NMMB, AND 00Z SPC WRF.

SOME OF THIS REGION HAS LOWERED FLASH FLOOD GUIDANCE/SATURATED
SOILS DUE TO RECENT RAINFALL.  DESPITE THE EXPECTED FORWARD
PROPAGATION, WHICH COULD BE AT SPEEDS UP TO 35 KTS, HOURLY RAIN
RATES IN EXCESS OF 2" ARE POSSIBLE WHERE CELLS MERGE AND/OR TRAIN.
 THE MORE RELIABLE MESOSCALE GUIDANCE SHOWS LOCAL AMOUNTS IN THE
3-5" RANGE ACROSS SOUTHERN PORTIONS OF THE LOWER PENINSULA OF MI
AND AROUND 2" ACROSS WESTERN NY AND NORTHWEST PA.  THE FLOW IN
GENERAL IS DEEPLY UNIDIRECTIONAL OUT OF THE WEST, MAKING BANDS OF
TRAINING THUNDERSTORMS A DISTINCT POSSIBILITY.


FRONT RANGE OF CO
~~~~~~~~~~~~~~~~~
UPSLOPE FLOW BEHIND A COLD FRONT COMBINED WITH SURFACE BASED CAPES
OVER 2000 J/KG DUE TO DAYTIME HEATING (PER 21Z SREF MEAN FORECAST
FIELDS) AND PRECIPITABLE WATER VALUES NEAR 1.25" ARE EXPECTED TO
INITIATE A CONVECTIVE COMPLEX IN EASTERN CO DURING DAYTIME HEATING
SUNDAY.  THERE IS A CONSISTENT SIGNAL ACROSS PORTIONS OF EASTERN
CO FOR LOCAL AMOUNTS OF 3"+. HOURLY RAIN RATES ACROSS EASTERN CO
COULD REACH/EXCEED 2", WHICH WOULD EXCEED THE LOW FLASH FLOOD
GUIDANCE VALUES SEEN IN POCKETS ACROSS EASTERN PORTIONS OF THE
STATE.  WHAT KEEPS THIS AREA A SEE TEXT RATHER THAN A SLIGHT RISK
IS THE POTENTIALLY SMALL SIZE OF IMPACT AND SOME UNCERTAINTY
REGARDING WHERE ACROSS EAST-CENTRAL OR NORTHEAST CO THE HEAVY RAIN
IS EXPECTED TO OCCUR.  BELIEVE THERE IS A BETTER CHANCE FOR THE
HEAVY RAINFALL TO FALL ACROSS EAST-CENTRAL CO THAN NORTHEAST
PORTIONS OF THE STATE.

ROTH
$$





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