Quantitative Precipitation Forecast
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FOUS30 KWBC 210200
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
959 PM EDT SAT SEP 20 2014

...VALID 03Z SUN SEP 21 2014 - 00Z MON SEP 22 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 WSW TPH 60 SSE NFL 10 N NFL 35 WSW WMC 30 NE WMC 25 WNW 9BB
30 SW DPG 15 N CDC 45 WSW SGU 30 NE DRA 20 WSW TPH.

...NV/WESTERN UT...
MADE NO CHANGE HERE.  VERY DEEP MOISTURE IN PLACE..PWS APPROACHING
1.25 INCHES AT VEF..A MODESTLY HIGH K INDEX OF 37 AT VEF..AND
LARGE SCALE LIFT ENHANCED BY PRONOUNCED UPPER DIFFLUENCE JUST
DOWNSTREAM OF THE CA CLOSED H5 LOW..WILL SUPPORT A RATHER
WIDESPREAD RAINFALL EVENT FOR A LARGE PART OF NV INTO UT THIS
PERIOD..WITH SOME LOCALLY HEAVY TO ISOLATED EXCESSIVE RAINFALL
AMOUNTS EXPECTED.  SOME OF THE MORE "REALISTIC" HIRES QPF GUIDANCE
INDICATES THE POTENTIAL FOR SMALL POCKETS OF 1-2 INCH RAINFALL
AMOUNTS IN SEVERAL HOURS INTO THE LATER SUNDAY AFTERNOON
HOURS..AND SEE NO REASON TO GO AGAINST THIS IDEA.  THE HEAVY
RAINFALL THREAT SHOULD LESSEN TOWARDS THE END OF THIS PERIOD AND
BEYOND AS THE CA CLOSED LOW OPENS UP AND BECOMES MORE PROGRESSIVE
INTO THE CENTRAL GREAT BASIN AREA.


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
45 SW CDS 10 S DYS 10 ENE E29 35 S 6R6 100 SW 6R6 65 S MRF
50 SE MMCS HMN 15 WSW 4CR 50 WNW CVS 40 NW PVW 45 SW CDS.

...SOUTHEASTERN NEW MEXICO & TEXAS...
ODILE`S REMNANT CIRCULATION PERSISTS AT THE LOW- AND MID-LEVELS --
CURRENTLY ENTERING NORTHWEST TX.  THE OVERALL PATTERN AND
THERMODYNAMIC SETUP REMAINS IN PLACE ACROSS THE AREA TO FAVOR
ADDITIONAL CONVECTIVE FORMATION THIS PERIOD WITH AREAS OF HEAVY
AND POTENTIALLY EXCESSIVE RAINFALL. CONTINUED SOUTHEASTERLY
LOW-LEVEL FLOW WILL MAINTAIN FAVORABLE MOISTURE TRANSPORT FROM THE
WESTERN GULF WHICH WEAKENS DURING THE DAY AND INCREASES
OVERNIGHT...WITH THE AREA ALIGNED ALONG THE AXIS OF MAXIMUM PWS
RANGING FROM ~1.5" IN SERN NM TO NEAR 2.5" IN SOUTHERN TX.  THESE
PWS ARE 2-2.5 SIGMAS ABOVE THE MEAN FOR MID- TO LATE-SEPTEMBER.
THIS DEGREE OF MOISTURE SUPPORTS HOURLY RAIN RATES AS HIGH AS 1-2"
ACROSS NM/SOUTHWESTERN TX..WHICH COULD CAUSE SOME FLOODING
PROBLEMS.

THE OVERNIGHT INCREASE IN INFLOW IS LIKELY TO AID MULTI-CELLULAR
ORGANIZATION AND SLOW PROPAGATION INTO THE LOW-LEVEL INFLOW
(INCREASED THREAT FOR CELL TRAINING) DURING THESE TIMES.  USING
LAST NIGHT/THIS MORNING AS A PROXY, THIS SORT OF DEVELOPMENT IS
NOT EXPECTED TO BE WIDESPREAD..SO KEPT ONLY A SLIGHT RISK IN
PLACE.  DEEPER INSTABILITY AND HIGHER CAPE VALUES DURING THE
AFTERNOON AND EVENING LEAD TO LESS-ORGANIZED, PULSE-TYPE
THUNDERSTORM ACTIVITY WITH MORE PROGRESSIVE OUTFLOW BOUNDARIES.
WHILE THE GUIDANCE GRADUALLY WEAKEN ODILE`S REMNANT
CIRCULATION..BROAD UPPER-LEVEL DIFFLUENCE WILL REMAIN IN PLACE IN
BETWEEN THE CLOSED UPPER HIGH OVER NW MEXICO AND THE FASTER
WESTERLIES/HEIGHT FALLS MOVING INTO THE MID-MS VALLEY.


...SOUTHEASTERN/SOUTHERN MID ATLANTIC COAST...
A BROAD UPPER LEVEL TROUGH WITH CONVECTIVE FRONTAL WAVES --
INCLUDING A STRENGTHENING AND INCREASINGLY DOMINANT COASTAL LOW
WELL OFFSHORE NORTHEAST FL/GA -- WILL FOCUS 25-35 KTS OF LOW-LEVEL
INFLOW NEAR SOUTH-CENTRAL FL TODAY AND CLOSE TO THE COASTLINE OF
THE SOUTHEAST US FROM THE GA COAST NORTHEAST THROUGH THE COAST OF
THE CAROLINAS.  PWS OF 2" ALONG WITH EXPECTED BOUNDARY LAYER
MOISTURE CONVERGENCE IN NC COULD SUPPORT SOME 1-2 INCH RAINS IN AN
HOUR OR SO..WITH THE POTENTIAL FOR HEAVY RAINS DECREASING LATER
SUNDAY AS THE WEAK SURFACE LOW PULLS OUT AND H85 FLOW TURNS TO
OFFSHORE.

TERRY
$$




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