EXCESSIVE RAINFALL DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
245 AM EDT MON JUN 07 2010
 
...VALID 06Z MON JUN 07 2010 - 12Z TUE JUN 08 2010...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...
 

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 SSW BVN 35 E ONL 10 NE SUX 25 NNE DNS DSM 15 S FFL
20 WSW UIN 40 NNE COU 35 SSE CDJ STJ 10 NNE FNB 15 SE JYR
25 SSW BVN.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE
FROM
15 S ICL OLU 25 SW SUX DNS 20 NNE LWD 20 SSE LWD 15 S ICL.

 
AS MENTIONED IN THE QPFPFD... A REAL DIFFICULT FORECAST DEVELOPING
OVER THE PLAINS INTO THE MS VLY OVER THE NEXT 24 HRS... AS A SOLID
ASSORTMENT OF MARITIME UPPER DYNAMICS SLIDES FROM THE NRN
ROCKIES/INTER-MOUNTAIN WEST INTO THE DAKOTAS ALONG A CONTINUED
ACTIVE AND PROGRESSIVE RELATIVELY FLAT UPPER JET. DESPITE THE
SOLID SHORT WAVE AND COLD FRONT ARRIVING INTO THE UPPER MIDWEST...
MOST OF THE ACTIVE CONVECTION AND HEAVY RAIN EXPECTED WILL OCCUR
SOUTH OF THIS FEATURE OR NEAR A QUASI-STATIONARY BECOMING WARM
FRONT EXTENDING FROM NE/KS INTO IA/MO. IT IS IN THIS REGION WHERE
THE SMALL SCALE WILL RULE... MEANING IT WILL BE VERY DIFFICULT TO
PINPOINT THESE SMALL SCALE DETAILS AND THUS LARGE MODEL SPREAD.
FOR EXAMPLE... THE ACTIVITY ACROSS WRN KS AT THE MOMENT... NONE OF
THE OPERATIONAL MODELS HAVE ANY IDEA THIS ACTIVITY EXISTS. AS A
RESULT... HPC LEANED VERY HEAVILY ON THE SREF MEAN ALONG WITH THE
ENSBC QPF TO FILTER OUT THE SMALL SCALE DETAILS. THE KNOWN FACTS
ARE THE THERMAL AXIS... DEEP PLUME OF LL MOISTURE RETURNING AND
POOLING INVOF OF THIS BOUNDARY AND AN ACTIVE LL H850 JET DIRECTED
INTO THE WARM FRONT... BEFORE THE SURFACE COLD FRONT ARRIVES FROM
THE WEST INTO THE UPPER PLAINS BY MON MORNING. THE COMBINATION OF
THESE FACTORS AND RESULTANT MODEL CHOICE/BLEND MEANS THE POTENTIAL
FOR TREMENDOUS WAA/ISENTROPIC LIFT QPF ALIGNED NEAR THE BOUNDARY
AND TO THE NORTH AND EAST OF IT FROM ERN/CENTRAL NE AND ERN KS
INTO IA/MO. HPC WENT WITH 1 TO 2 INCH OR GREATER AMOUNTS HERE...
THINKING THIS IS THE APPROPRIATE PATH TO TAKE ON QPF
LOCATION/AMOUNTS AND MODEL BLEND. ALSO... A GOOD PART OF THIS
REGION WAS IMPACTED SIGNIFICANTLY A FEW NIGHTS AGO WITH
BACK-BUILDING CONVECTION AND TRAINING HEAVY RAINFALL... THUS FFG
IS ALREADY LOW HERE. 3 HRLY GUIDANCE INDICATES AROUND AN INCH
COULD CAUSE SERIOUS FLASH FLOODING ISSUES OR AT LEAST RUNOFF
PROBLEMS. HPC WILL UPGRADE THE PREVIOUS SEE TEXT AND ISSUE A
SLIGHT AND MDT AREA FOR EXCESSIVE RAINFALL.   

MUSHER
$$