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Excessive Rainfall Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1407Z Jul 30, 2014)
 
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Abbreviations and acronyms used in this product
 
Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1007 AM EDT WED JUL 30 2014

...VALID 15Z WED JUL 30 2014 - 12Z THU JUL 31 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 WNW ELD 35 SSW TXK 15 SSW OSA 10 SSE GVT ADS 15 NW NFW
15 E RPH 45 SSW F05 15 S AMA 15 W DUX 25 E CAO 10 N CAO
15 NNW CAO 35 NNW CAO 45 NNW CAO TAD VTP 25 SSE MYP 20 NNE GUC
20 NNE RIL 35 W EEO 35 SW VEL 35 NNE PUC 35 E PVU 15 E PVU
30 ENE SLC 20 NE LGU 20 NNE U78 25 E RXE 40 NNW JAC WEY
25 NNE WYS 40 SSE LVM 50 NNW COD COD 30 SSE COD 30 NNW RIW
15 ESE RIW 30 SSW HLD 10 NW PAT 10 NE PAT 20 SW DRC 20 S DRC
25 WNW BRX 15 SSE TOR 25 NNW SNY 30 W OGA 20 W IML 45 NNW GLD
20 N GLD 10 NE GLD 35 SW HYS 35 ESE AAO 25 E ROG 10 N LRF
25 N ELD 20 WNW ELD.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
30 E AQR 15 E ADH 15 SSW JWG 30 SE WWR 15 NNW WWR 30 N WWR
15 NNW AVK 15 NNW WDG 10 SSE RVS 15 NNW JSV 10 WSW FSM
20 SSE RKR 35 NNW DEQ 30 E AQR.


GIVEN THE LOW ONE AND THREE HOUR FLASH FLOOD GUIDANCE VALUES
ACROSS SOUTHEAST WY AND NORTHEAST CO (DUE TO ACTIVITY TUE
AFTERNOON/EVENING)...THIS AREA APPEARS TO BE VULNERABLE AGAIN
DURING THIS PERIOD. LOCAL RADARS AND RADAR WIND PROFILES CONTINUE
TO SHOW THE UPSLOPE CONTINUING IN SOUTHEAST WY AND NORTHEAST
CO...AS THE LOW LEVEL FRONT NORTH OF THE FLOW PERSISTS. THERE ARE
MEMBERS OF THE HIGH RESOLUTION GUIDANCE (IN PARTICULAR THE 00Z
SSEO MEAN AND THE 00Z ARW) THAT SHOW THE POTENTIAL FOR MORE THAN
AN INCH IN SIX HOURS LATE THIS MORNING AND INTO THE AFTERNOON.
GIVEN THAT ONE HOUR FLASH FLOOD GUIDANCE VALUES ARE AS LOW AS O.50
INCHES ACROSS PORTIONS OF NORTHEAST CO...THERE IS A THREAT FOR
FLASH FLOODING. THUS...THE SLIGHT RISK AREA WAS EXPANDED TO
INCLUDE THE ABOVEMENTIONED AREAS. PLEASE REFERENCE MESOSCALE
PRECIPITATION DISCUSSION 234 (MPD)...IN EFFECT UNTIL ABOUT 19Z...
FOR MORE DETAILS.

THE 12Z ANALYSIS SHOWED A PLUME OF 1.25 INCH PRECIPITABLE WATER
EXTENDING FROM NORTHEAST UT THROUGH SOUTHEAST WY AND NORTHEAST
CO...WHICH IS BETWEEN TWO AND THREE STANDARD DEVIATIONS ABOVE
NORMAL. THE LATEST WV LOOP SHOWED A SHORT WAVE OVER NORTHEAST
UT...MOVING EAST IN THE GENERAL WEST NORTHWEST MID LEVEL FLOW. AS
THE SHORT WAVE INTERACTS WITH THE HIGHLY ANOMALOUS MOISTURE
PLUME...THE SYNOPTIC SCALE ASCENT SHOULD AID IN THE FORMATION OF
AT LEAST SCATTERED CONVECTION IN THE PRESENCE OF MARGINAL
INSTABILITY ACROSS NORTHEAST UT INTO THE TERRAIN OF WESTERN WY.
DUE TO ACTIVITY TUE AFTERNOON...THE ONE HOUR FLASH FLOOD GUIDANCE
VALUES HAVE DROPPED TO AS LOW AS AN INCH ACROSS THE GRAND TETONS.
BASED ON THIS...THE SLIGHT RISK WAS EXPANDED TO INCLUDE THE
ABOVEMENTIONED AREAS.

AN MCV...QUITE EVIDENT IN THE REGIONAL RADAR LOOP...IS DRIVING
CONVECTION ALONG AND SOUTH OF THE FRONT ACROSS CENTRAL OK THIS
MORNING. THE MCV SHOULD CONTINUE TO PROVIDE THE NECESSARY LIFT FOR
THE CONVECTION TO CONTINUE ALONG THE AXIS OF BEST INSTABILITY
ACROSS CENTRAL AND SOUTHEAST OK INTO HE AFTERNOON HOURS. THERE IS
A MULTI MODEL SIGNAL IN BOTH THE GLOBAL AND HIGH RESOLUTION
GUIDANCE THAT BETWEEN 3 AND 4 INCHES OF QPF IS POSSIBLE ALONG THIS
AXIS. IT APPEARS AS THOUGH THE LATITUDINAL QUESTION IS BEING
RESOLVED BY THE ACTIVITY IN PLACE...WHICH IS A BIT SOUTH OF THE
MODEL CONSENSUS LOCATION. THE WPC QPF WILL FOLLOW THIS TREND...AS
CAPPING SHOULD NOT BE AN ISSUE. THE MODERATE RISK AREA WAS
ADJUSTED BASED ON THE ABOVE REASONING. PLEASE REFERENCE MPD
233...IN EFFECT UNTIL ABOUT 18Z...FOR MORE DETAILS.


HAYES