EXCESSIVE RAINFALL DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
235 PM EDT FRI JUL 03 2009
 
...VALID 18Z FRI JUL 03 2009 - 00Z SUN JUL 05 2009...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...
 

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
10 NW SUS 30 NNW COU 10 ENE MCI 20 S FNB 20 NNE BIE 15 WSW FET
20 WSW DNS 15 SE MIW 20 WSW PIA 10 SE MTO SLO 10 NW SUS.

 
...MID MS VLY...

THREAT OF HEAVY TO PSBL EXCESSIVE RAINS WILL EXIST FROM PORTIONS
OF ERN NE SEWD THROUGH SRN IA/NRN MO INTO SOUTH CENTRAL IL... AS
S/WV ENERGY SHEARS EWD... OUT OF THE WEST.. OVER A FLATTENING UPR
RIDGE. THE UPPER DYNAMICS WILL HELP IGNITE SURFACE CYCLOGENESIS
NEAR AN ACTIVE WARM FRONT WHICH WILL SLIDE MAINLY EAST/ESE OVER
THE TOP OF THE UPPER RIDGE AXIS INTO THE OH VLY ON SAT. A
STRENGTHENING LOW LEVEL JET OF 40 KTS OR SO AHEAD OF THE WAVE WILL
HELP SUPPORT STG MSTR FLUX N OF THE WARM FRONT WITH MODEST UPPER
DIVERGENCE FROM RT ENTRANCE REGION OF UPR JET STREAK..ALL OF WHICH
SHOULD SUPPORT A BAND OF MDT TO HEAVY CONVECTIVE RAINS ACROSS
PORTIONS OF THE MID MS VLY. IMPRESSIVE MSTR WILL BE AVAILABLE FROM
THE GULF BUT ALSO FROM THE SW OR MONSOONAL FETCH..AS PWS POOL NEAR
2.00 INCHES..WHICH SHOULD SUPPORT A STRIPE OF 1 TO 2 INCH PLUS
RAINS WITH ISOLD AMOUNTS NEAR 4 INCHES CLOSE TO THE EXPECTED 85H
LOW TRACK..WHERE STGEST LOW LEVEL SPEED/DIRECTIONAL CONVERGENCE IS
FCST. THE ONLY QUESTION MARK IS WITH THE MODEL GUIDANCE... SOME
SPREAD EXISTS ON POSSIBLY FOCUSING THE FORCING/HEAVY RAINFALL AXIS
TOO FAR NORTH INTO THE MODEST COLD SECTOR THAN NEAR THE BEST
CONVERGENCE AND THE MODELS PERFORMED QUITE POORLY SEVERAL WEEKS
AGO WITH PIECES OF ENERGY EJECTING OUT OF THE WEST INTO THE
PLAINS. NEEDLESS TO SAY... HPC WILL STICK WITH A SLIGHT RISK OF
EXCESSIVE RAINS DESPITE FFG BEING REASONABLY HIGH.

...AZ/NM...
THE THREAT FOR SLOW MOVING CONVECTION AND HEAVY RAINFALL WILL
CONTINUE LATE THIS AFTN AND SAT ACROSS PORTIONS OF AZ AND NM. AN
UPPER RIDGE... EAST OF THE REGION... WILL KEEP FUNNELING NORTH
DEEP MONSOONAL MOISTURE INTO SW AS PW NUMBERS THIS MORNING ARE
EASILY AOA 1.5 TO 1.75 INCHES. THE COMBINATION OF THIS DEEP
MOISTURE PLUME... A MID-LEVEL CIRCULATION MOVING NORTH OUT OF NRN
MEXICO AND LEFTOVER MESOSCALE BOUNDARIES SHOULD FUEL THE SCATTERED
HEAVY RAINS. THE OVERALL STEERING CURRENT FROM 850 TO 750 MB IS 5
KTS OR LESS WHICH MEANS THE DEVELOPING ACTIVITY SHOULD MOVE VERY
SLOWLY NORTH AND EAST AROUND THE WRN EDGE OF THE 500 MB RIDGE
AXIS. ADD THE FACT MOISTURE/RAINFALL FROM THE LAST FEW DAYS HAS
IMPACTED THIS AREA... IT WILL NOT TAKE MUCH FOR THE ACTIVITY TO
LEAD TO HEAVY TORRENTIAL DOWNPOURS AND RUNOFF ISSUES.        


MUSHER