Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 161125
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
724 AM EDT TUE SEP 16 2014

...VALID 12Z TUE SEP 16 2014 - 12Z WED SEP 17 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
65 SSE MMCS 100 SW MMCS 40 SW OLS 40 S NYL 30 S NJK 10 ENE CZZ
30 NW PSP 35 NE DAG 10 SSE DRA 25 NW VGT 40 N LSV 25 ESE LSV
50 NNE IGM 45 SSE SGU 55 NW GCN 20 WNW GCN 45 NNW GCN 45 WSW PGA
25 ENE 40G 35 NNW SOW 55 ESE SJN 60 NE TCS 10 E SRR 25 ESE SRR
15 SW ROW 15 S ATS 25 W CNM 25 WNW GDP 45 WSW GDP 65 SSE MMCS.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 SE HXD 15 ESE SSI SGJ 25 S VQQ 40 ESE VLD 15 W AYS 25 S VDI
20 N SAV 10 W NBC 20 SE HXD.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
50 W OLS 50 SE YUM 20 WSW NYL 20 S BLH 55 ENE BLH 50 NE FFZ
15 SE SOW 40 SSE SJN 70 SSE SJN 45 WNW TCS 20 SW TCS 20 W HMN
30 SSW HMN 20 SSW LRU 55 ESE DUG 25 SW DUG 20 WSW OLS 50 W OLS.



SOUTHWEST
~~~~~~~~~
AN INCREASING HEAVY RAIN/FLASH FLOOD THREAT IS EXPECTED THIS
PERIOD AS MUCH ABOVE AVERAGE PRECIPITABLE WATER VALUES (PWS) WILL
CONTINUE TO PUSH NORTHWESTWARD INTO THE DESERT SOUTHWARD WITHIN
THE NORTHERN PERIPHERY OF ODILE. PW ANOMALIES OF 2-4.5 SIGMAS
ABOVE THE MEAN -- NEAR RECORD VALUES FOR MID-SEPTEMBER -- ARE
ANTICIPATED ACROSS THE SOUTHWESTERN U.S. FROM FAR SOUTHEAST CA,
FAR SOUTHERN NV, MUCH OF AZ, SOUTHERN NM, AND WESTERNMOST TX.
THERE ARE HINTS WITHIN THE 00Z AND 06Z SSEO NEIGHBORHOOD
PROBABILITIES (USING THE 30%+ CHANCE OF EXCEEDING FLASH FLOOD
GUIDANCE AS A GUIDE) THAT THE EXCESSIVE RAINFALL THREAT SHOULD
ENCOMPASS MUCH OF THE AREA OF SIGNIFICANTLY ABOVE NORMAL MOISTURE,
WHERE EXPECTED INSTABILITY INTRODUCED BY DAYTIME HEATING IN A
CLEAR AREA AND 25+ KTS OF 700 HPA INFLOW (PER RECENT RAP RUNS)
COULD ORGANIZE CONVECTION NEAR THE INTERNATIONAL BORDER.  THE
EXPECTED EASTERLY LOW-LEVEL FLOW SHOULD ALLOW CONVECTION WHICH
BUILDS WITHIN TOPOGRAPHY ACROSS SOUTHEAST AZ AND THE MOGOLLON RIM
TO MIGRATE OUTWARD TOWARDS VALLEY/DESERT FLOORS TODAY.  WITH AN
UPSLOPE FLOW INTO THE TERRAIN OF SOUTHERN CA, THE EASTERN SIDE OF
THE COASTAL RANGES TO THE EAST OF SAN DIEGO CANNOT BE RULED OUT OF
THE EXCESSIVE RAINFALL THREAT.  BOTH THE SLIGHT AND MODERATE RISKS
FOR EXCESSIVE RAINFALL WERE EXTENDED WESTWARD TO ACCOUNT FOR THIS
EXPECTATION.  LOCAL AMOUNTS OF 2-4" ARE POSSIBLE HERE WHERE CELLS
MERGE AND/OR TRAIN, WHICH WOULD APPROACH ANNUAL AVERAGE RAINFALL
AMOUNTS FOR THE REGION.  THIS EVENT EXPECTED OVER THE NEXT FEW
DAYS COULD RIVAL THAT OF MONDAY SEPTEMBER 8 WHICH OCCURRED AROUND
THE PERIPHERY OF NORBERT.


COASTAL SOUTHEAST AND FAR NORTHEAST FLORIDA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
A SLIGHT RISK AREA LIES ALONG COASTAL GA AND FAR NORTHEAST FL THIS
PERIOD FOR ANOTHER ROUND OF POTENTIALLY HEAVY TO ISOLATED
EXCESSIVE RAINFALL AMOUNTS.  AN AXIS OF ABOVE AVERAGE PW VALUES---
1.5+ STANDARD DEVIATIONS ABOVE THE MEAN---WILL PERSIST THIS PERIOD
IN THE VICINITY OF THE WEAKENING STATIONARY FRONTAL BOUNDARY
CURRENTLY STRETCHING ALONG THE GULF COAST INTO THE COASTAL
SOUTHEAST.  WIDESPREAD SCATTERED CONVECTION LIKELY AGAIN ALONG AND
SOUTH OF THIS FRONT IN A REGION OF ENHANCED UVVS FROM FAVORABLE
RIGHT ENTRANCE REGION UPPER JET DYNAMICS EXPECTED TO MOVE ACROSS
THIS AREA LATE AFTERNOON/EVENING.  ISOLATED VERY HEAVY RAINFALL
AMOUNTS HAVE FALLEN THE PAST TWO DAYS ALONG COASTAL SECTIONS OF SC
AND GA---WITH THIS POTENTIAL AGAIN POSSIBLE ALONG COASTAL GA INTO
FAR NORTHEAST FL.  THE HI RES RUNS ARE MOST EMPHATIC ABOUT HEAVY
RAINFALL POTENTIAL ACROSS THESE AREAS---WITH ISOLATED TOTALS OF
3-5"+ POSSIBLE.

ROTH/ORAVEC
$$





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