Quantitative Precipitation Forecast
Issued by NWS

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000
FOUS30 KWBC 252153
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
552 PM EDT SAT JUL 25 2015

...VALID 21Z SAT JUL 25 2015 - 12Z SUN JUL 26 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 S APF 50 W APF 50 SSW SRQ 40 W SPG 30 WNW PIE 15 SSW BKV
15 SSE BOW 45 NE RSW 45 ENE APF 45 ESE APF 45 W TMB 50 SSE APF
40 SSE APF 30 S APF.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 N FAM 20 NE AIZ IXD 40 WNW EMP 20 WSW SLN 45 N RSL
25 ESE HSI 15 SE AIO 10 WSW OTM 20 NNE UIN 10 E ALN 25 N FAM.


21Z UPDATE...

PULLED THE SLIGHT RISK AREA A LITTLE FARTHER WESTWARD ACROSS
SOUTHEAST NE AND NORTHEAST KS...TO ACCOUNT FOR THE CONVECTION IN
THE NEAR TERM (21-03Z)...WHILE EXTENDING THE AREA A LITTLE FARTHER
SOUTH OF TOP-MCI GIVEN THE CONTINUED UPTICK IN DEEP-LAYER
INSTABILITY (MIXED LAYER CAPES 4000-4500 J/KG) ALONG WITH THE
INCREASE IN 925-850 MB FGEN (SUBTLE INCREASE IN RIGHT ENTRANCE
REGION FORCING PER THE UPPER JET AXIS ACROSS THE NORTHERN
PLAINS-UPPER MS VALLEY)...LOW LEVEL MOISTURE FLUX
CONVERGENCE...AND A WEAKENING OF THE MID LAYER CAP. THE
EXPECTATION IS THAT THE CONVECTION WILL BECOME MORE ELEVATED WITH
TIME THIS EVENING (AS IT ALREADY IS NORTH OF THE SURFACE FRONT --
WITH THE LOW-LEVEL ISENTROPIC ASCENT ABLE TO BYPASS ANY LOW-LAYER
CIN AND ALLOW PARCELS TO MORE EFFICIENTLY REACH THE LFC).
MOREOVER...AS THE LATE AFTERNOON CONVECTION CONTINUES TO BECOME
MORE ELEVATED...ANTICIPATE THE ACTIVITY TO BECOME BETTER ORGANIZED
WITH THE ONSET OF THE LLJ...WITH THE ANOMALOUS PWS (AROUND 2.00
INCHES)...STRENGTHENING LOW-LEVEL MOISTURE TRANSPORT/FLUX
CONVERGENCE INTO AND NORTH OF THE SURFACE BOUNDARY...AND HIGH WET
BULB ZERO LEVELS/WARM CLOUD DEPTHS (OVER 12,000/10,000 FT
RESPECTIVELY) LEADING TO FAVORABLE WARM RAIN PROCESSES AND
PRECIPITATION EFFICIENCY. THE 12Z WRF-ARW...WRF-NMMB...AND
NSSL-WRF SEEM TO HAVE A GENERAL IDEA REGARDING THE LATE-AFTERNOON
ACTIVITY...THOUGH WOULD APPEAR TO BE NOT FAR ENOUGH SOUTH WITH THE
HIGHER QPF GOING INTO THIS EVENING.

FOR FURTHER DETAILS REGARDING ANY ACTIVE MESOSCALE PRECIPITATION
DISCUSSIONS (MPD) WITHIN THE EXCESSIVE RAINFALL OUTLOOK AREA...
PLEASE REFER TO THE LINK ON THE WPC HOME PAGE ABOVE THE TOP NEWS
OF THE DAY...OR GO DIRECTLY TO THE MPD PAGE:
WWW.WPC.NCEP.NOAA.GOV/METWATCH/METWATCH_MPD.PHP.

HURLEY


PREVIOUS DISCUSSION FOLLOWS...


...SOUTHWEST FLORIDA...

THE PREVIOUS EXCESSIVE RAINFALL POTENTIAL OUTLOOK WAS EXTENDED
SOUTHWARD INTO SOUTHWEST FLORIDA FOR THE UPCOMING PERIOD.
THE AXIS OF MUCH ABOVE AVERAGE PW VALUES THAT HAS BEEN TO THE
SOUTH OF THE STATIONARY FRONTAL BOUNDARY DRAPED ACROSS THE
SOUTHEAST WILL BE PUSHING SLOWLY SOUTHWARD THIS PERIOD ACROSS
NORTHERN TO CENTRAL FLORIDA.  THIS SHOULD FOCUS THE AXIS OF THE
HEAVIEST RAINS FARTHER TO THE SOUTH THAN HAS BEEN OBSERVED OVER
THE PAST 24 HOURS.  ANOMALOUSLY STRONG MOISTURE FLUX FROM WEST
SOUTHWESTERLY LOW LEVEL FLOW OFF THE GULF OF MEXICO IN AN AXIS OF
2.25"+ PW VALUES WILL SUPPORT WIDESPREAD HEAVY TO ISOLATED
EXCESSIVE RAINFALL AMOUNTS---FOCUSING ON SOUTHWEST FLORIDA FROM
TAMPA SOUTHWARD.  THERE IS MODEL CONSENSUS FOR A MAX AXIS OVER
SOUTHWEST FLORIDA THIS PERIOD---BUT MORE SPREAD WITH RESPECT TO
QPF AMOUNTS INLAND ACROSS LARGE PORTIONS OF THE PENINSULA.  WHILE
FFG VALUES ARE HIGH OVER SOUTHWEST FLORIDA---INTENSE RAINFALL
RATES---ESPECIALLY OVER URBANIZED AREAS---WILL SUPPORT POTENTIAL
FOR ISOLATED RUNOFF ISSUES.


...LOWER MO VALLEY...

ADDITIONAL SHORTWAVE ENERGY MOVING EASTWARD ALONG THE SOUTHERN
EDGE OF THE WESTERLIES WILL SUPPORT POTENTIAL FOR ADDITIONAL
ORGANIZED CONVECTION ACROSS PORTIONS OF THE CENTRAL PLAINS INTO
THE LOWER MO VALLEY THIS PERIOD. CONFIDENCE IS RATHER LOW WITH
DETAILS OF THE MAX QPF AXIS AS THERE IS A WIDESPREAD IN MODEL
SOLUTIONS.  THE FARTHER SOUTHERN QPF AXES OF THE GFS AND SEVERAL
OF THE HI RES MODELS WERE FAVORED.   WITH THE POTENTIAL FOR
ADDITIONAL ORGANIZED CONVECTION IN AN AXIS OF ABOVE AVERAGE PW
VALUES/ENHANCED UPPER DIFFLUENCE AHEAD OF THE ABOVE MENTIONED
SHORTWAVES---ISOLATED EXCESSIVE RAINFALL AMOUNTS ARE POSSIBLE
WHERE CONVECTION DOES ORGANIZE---ESPECIALLY IF THIS ADDITIONAL
CONVECTION MOVES OVER AREAS THAT ARE RECEIVING HEAVY RAINFALL
AMOUNTS EARLY THIS MORNING.

ORAVEC
$$





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