EXCESSIVE RAINFALL DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
1007 AM EDT SAT APR 23 2011
 
...VALID 15Z SAT APR 23 2011 - 12Z SUN APR 24 2011...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...
 

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 E BWG 15 ENE DYR 20 S M19 25 SSE RUE 10 NW MWT 35 NNE PRX
10 E ADS GDJ 15 S SEP 30 NNW 7F9 35 WNW GLE 10 SE PVJ 20 SW MKO
MKO XNA 35 S SGF 20 SE SGF 30 E SGF 40 SW TBN 25 WSW TBN
15 SSE AIZ AIZ 10 NNE AIZ 20 SW JEF 10 SW JEF 10 E JEF
30 ENE JEF 35 WNW SUS 15 NW SUS SET 15 E ALN 25 NW SLO
15 WNW 1H2 10 ENE HUF 10 WNW SGH 15 WSW PHD 15 S FIG 20 E SEG
CXY 25 SSW CBE 25 ESE HTS 35 NW SME 10 E BWG.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE
FROM
30 NNE UNO 40 SW FAM 15 WSW FAM FAM 20 ENE FAM 20 SW SAR AJG
20 NW CVG 10 N UNI 45 NW HTS 25 SE LOU 25 S OWB 40 NNW HOP
20 NNW BYH 30 W RUE 10 NNE RKR 15 NNE JSV 15 WNW HRO 30 NNE UNO.

 
UPDATE...

CHANGES TO THE PREVIOUS EXCESSIVE RAINFALL POTENTIAL OUTLOOK WERE
RELATIVELY MINOR...BASED MOSTLY ON CURRENT RADAR TRENDS WITH
ONGOING CONVECTION.  NO CHANGES IN OVERALL THINKING FROM PREV
OUTLOOK ON A LARGE THREAT REGION THIS PERIOD FROM ERN PORTIONS OF
THE SRN PLAINS...ENEWD THRU THE MID MS VALLEY AND OH VALLEY. 
WHILE OVERNIGHT CONVECTION HAS WEAKENED OVR THE OH
VALLEY..ADDITIONAL ORGANIZED ACTIVITY ALONG THE STNRY FRONTAL
BNDRY IS LIKELY AGAIN LATER TODAY...ESPECIALLY SAT NIGHT INTO
EARLY SUN AT CONVECTIVE MAX TIME.  MOISTURE FLUX INTO THE BNDRY AT
THIS TIME IS EXPECTED TO STRENGTHEN...WITH ADDITIONAL HEAVY
RAINFALL OVER AREAS OF THE OH RIVER VALLEY THAT HAVE RECEIVED
SEVERAL INCHES OVR THE PAST 24 HRS LIKELY.  THIS EXPECTED
CONVECTION AND ONGOING CONVECTION OVR ERN OK...NRN AR AND SRN MO
WARRANTS A LARGE MDT RISK FOR PCPN AMTS EXCEEDING FFG
VALUES...WITH WIDESPREAD 1-2"+ PCPN AMTS EXPECTED THIS PERIOD AND
ISOLATED TOTALS 3-5"+.  THE LATEST HI RES RUNS ARE KEYING IN ON
NRN AR/FAR SRN MO FOR THE HEAVIEST TOTALS THIS PERIOD IN ASSOC
WITH ONGOING ACTIVITY..WITH TOTALS OF 3-5"+.  

ORAVEC

PREVIOUS DISCUSSION...

FRONT/PRE-FRONTAL CNVGNC ZONE/OUTFLOW BNDRYS WILL CONCENTRATE MSTR
CNVGNC ALONG THE RATHER LARGE OUTLOOK AREA TODAY.  PROBLEM IS IT
THAT IT IS DIFFICULT TO RULE OUT EXCESSIVE RAINS ANYWHERE WITHIN
THIS RATHER LARGE AREA AS THE INTERACTION OF SYNOPTIC AND
MESOSCALE FORCING OCCURS. IN ADDITION..GAUGING THE EFFECT OF WEAK
IMPULSES EMBEDDED IN THE SWLY FLOW ALOFT IS AN ISSUE. MSTR AVBLTY
PER PWS MORE THAN ADEQUATE TO SUPPORT INTENSE RNFL RATES AND A
BROAD AREA OF DIV FLOW ALOFT WILL BE IN PLACE TO AID CNVCTV
DVLPMNT.  IT WOULD SEEM THE BEST CHANCES FOR HEAVIEST ACTVTY IS
ACROSS THE MID MS/LWR OH VLYS WHERE THE BEST MSTR FLUX INTO THE
FRONTAL BAND WILL BE CONCENTRATED..AS WELL AS THE LIKELIHOOD OF
MULTIPLE CNVCTV AREAS REPEATING OVR THE REGION. WIDESPREAD 1.00 TO
2.00 INCH RAINS ARE LIKELY WITHIN THE OUTLOOK AREA WITH ISOLD AMTS
IN EXCESS OF 3.00 TO 4.00 INCHES PSBL..PARTICULARLY INVOF THE MID
MS/LWR OH VLY REGION.

KORTY
Á$$