EXCESSIVE RAINFALL DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
119 PM EDT MON APR 18 2011
 
...VALID 18Z MON APR 18 2011 - 00Z WED APR 20 2011...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...
 

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 S HLG IDI 10 SW FIG 25 W IPT 10 E SEG CXY 25 WNW THV
15 WNW HGR 10 SSW CBE 20 E CKB 20 WNW CKB 20 S HLG.


THE MODELS DIFFER ON WHETHER THE PRECIP DEVELOPS AND EXTENDS TO
THE EAST ALONG THE SFC WARM FRONT OR FURTHER NORTH ALONG THE 850
MB FRONT AND AXIS OF LOW LEVEL JET/HIGHER PW VALUES.  THE GFS
SEEMS TO DEVELOP THE CONVECTION ALONG BOTH BOUNDARIES...WITH THE
NAM/CANADIAN REGIONAL GEM/09Z SREF MEAN/THE HIGH RES WRF FARTHER S
TOWARDS THE SFC WARM FRONT AND LOW LEVEL JET MAXIMA.  EXPECT A
BAND OF 1-2 INCH RNFL AMTS NOT TOO FAR N OF THE OH RVR OVR SRN
PTNS OF SRN IL INTO SRN IN AND SRN OH.  IF THIS CONVECTION HOLDS
TOGETHER AS THE LOW LEVEL JET COMES INTO SOUTHWEST PA...IT
ENCOUNTERS AREAS OF LOWER FLASH FLOOD GUIDANCE VALUES OF HALF TO
THREE FOURTHS OF AN INCH.  THE 12Z HIGH RES WRF NMM/12Z NAM/09Z
SREF MEAN FORECASTS THESE AMOUNTS 12-18Z TUE...WITH LIGHTER
AMOUNTS FROM THE OTHER MODELS.

PETERSEN

$$