EXCESSIVE RAINFALL DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD 923 PM EDT THU JUN 10 2010 ...VALID 03Z FRI JUN 11 2010 - 00Z SAT JUN 12 2010... ...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL... SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM 35 NNW GLH 15 N BQP 30 W BQP 40 E BAD 15 SSE BAD 30 SSE GGG 15 SE JSO PSN 20 WNW PSN 20 ENE CRS 20 ENE LNC 20 SE TRL 10 SW SLR 30 WNW DEQ 30 SE FSM 25 N RUE 40 W POF 30 ESE FAM 10 N MWA 10 N M30 25 NNE DYR 15 WSW UTA 35 NNW GLH. SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM 15 SSW BKX MML 10 W MIC 20 ENE FBL 20 ESE RGK 20 ENE EAU MDZ AUW CLI 30 NW UNU 25 SSE VOK 20 ENE DEH 15 NE CCY 15 E MCW 10 ESE MCW 25 SE FRM 15 NW SPW 10 ENE SUX 20 S SUX 25 NW FET 10 N OLU 15 NNW BVN 25 NNE ODX 35 SE ANW 20 W ANW 35 WNW ICR 40 SSW PIR 10 WSW PIR 30 NNE PIR 35 ENE PIR 45 N 9V9 35 WNW HON 15 WNW HON 20 SSW HON 25 SSW HON 15 SSW BKX. TOTAL RAINFALL AMOUNTS OF FIVE INCHES WILL BE POSSIBLE TO THE RIGHT OF A LINE FROM LRF 15 S LIT 25 SSW LIT 25 ESE M89 30 NNW ELD 30 ESE TXK 20 SSE TXK 20 WSW TXK 20 SSW DEQ 10 NE DEQ 20 WSW MWT 15 ENE MWT 25 NNE HOT 15 WNW LZK LRF. NERN TX...FAR NWRN LA...SCNTRL AR... THE CONVECTION LIKELY TO REMAIN WELL DEFINED AND VERY SLOW MOVG INVOF A SLOW MOVG MID LEVEL VORT. THE SYSTEM WL REMAIN EMBEDDED IN AN AXIS OF ABOVE AVERAGE PW VALUES..2-2.25"+. THIS WL CONT TO SUPPORT ACTIVE CONVECTION INVOF THE CNTR OVERNIGHT. ACTIVITY SHOULD EXTEND FURTHER AWAY TO THE NORTHEAST FRIDAY AS THE MODELS SHOW THE MID LEVEL ABSOLUTE VORTICITY BECOMING STRETCHED AND SHEARED TO HE NORTHEAST. THE UPPER LEVEL WINDS INCREASE...WITH INCREASING SHEAR INCREASING THE FORWARD MOTION OF CELLS. CONSEQUENTLY...BEST POTENTIAL FOR HEAVY RAINS IS IN AR TONIGHT AND SLOWLY DIMINISHES FURTHER DOWNSTREAM FRIDAY. SHORT TERM PCPN AMTS OF 2"+ POSSIBLE IN AN HOUR OR TWO IN AREAS OF TRAINING OR STNRY CONVECTION TONIGHT...WITH LOCALLY 5 INCHES POSSIBLE FOR AN EVENT TOTAL IN SOUTHWEST AR TO FAR NORTHEAST TX. A SLIGHT RISK IS INDICATED SINCE FLASH FLOOD GUIDANCE VALUES ARE 2-4 INCHES ACROSS AR...WITH NONE OF THE MODELS FORECASTING 4 OR MORE INCHES. CNTRL-NRN PLAINS INTO THE UPR MS VALLEY...UPR LAKES REGION... LATEST SATL AND RADAR IMAGERY SHOW CONVECTION DEVELOPING OVER NEBRASKA/SOUTH DAKOTA AHEAD OF THE SFC WAVE AND LOW LEVEL WARM FRONT FCST TO PUSH ENEWD INTO THE UPR MS VALLEY AND UPR LAKES REGION THIS PERIOD. ALL GUIDANCE IS SIGNALING POTENTIAL FOR HEAVY PCPN AMTS ACRS THIS REGION. THERE IS STILL A NORTH-SOUTH SPREAD WITH THE MAX AXIS....WITH THE HIGH RESOLUTION ADVANCED RESEARCH WRF IN BETWEEN THE FURTHER NORTH NAM AND FURTHER SOUTH ECMWF. CONTINUED LOW LEVEL MOISTURE FLUXES WITH THE 12Z ECMWF FORECASTING PW VALUES TO INCREASE TO 2 INCHES BY FRI AFTERNOON SUPPORT HEAVY DOWNPOURS IN THE VICINITY OF THE LOW LEVEL WARM FRONT...AS THE MODELS/ENSEMBLE MEANS SHOW UPPER DIVERGENCE MAXIMA MOVING EAST NORTHEAST TRIGGER ASCENT ALONG THE FRONTAL ZONE. SHRT TERM PCPN AMTS OF 1-2" AND ISOLATED TOTALS OF 2-4" POSSIBLE THIS PERIOD ACRS THE REGION. AN SHARP INCREASE IN FLASH FLOOD GUIDANCE VALUES FURTHER NORTH IN MN/WI PRE EMPTED EXPANDING THE THREAT AREA FURTHER NORTH. PETERSEN $$