EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
249 AM EDT SUN MAY 19 2013

...VALID 06Z SUN MAY 19 2013 - 12Z MON MAY 20 2013...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
EST 40 WNW YKN 45 E IEN 25 ESE SIB 25 W IDV 30 SSE 3HT
25 SSE LWT 60 WSW JDN 25 W MLS 30 SW KS25 KRUG 20 NNW HCO
35 SSE CYQK 25 NNW CYQT 30 WNW CMX 10 NNE PBH 15 SSW LUM EST.


...NRN HIGH PLAINS EAST INTO THE UPPER MISSISSIPPI VALLEY...

THE MUCH DISCUSSED WRN U.S. UPPER TROUGH WILL TAKE ON A MORE
NEGATIVE TILT WHILE GRADUALLY MOVING INTO THE PLAINS TODAY. THE
ANTICIPATED BROAD AREA OF STRONG UPPER LEVEL DIFFLUENCE AND AGEOS
DIVERGENCE WILL ENSUE WITH THE AMPLIFICATION AND DEVELOPING UPPER
LEVEL "S" PATTERN...AIDED BY THE  COUPLING JET DYNAMICS VIA THE
LEFT EXIT/RIGHT ENTRANCE REGION OF THE SRN/NRN BRANCHES
RESPECTIVELY.
THIS WILL GENERATE A FAIRLY SIZABLE AREA OF ASCENT...COINCIDING
WITH PROLONGED MOIST INFLOW (~30 TO 40 KTS AT 850 MB WITH PW'S OF
1 TO 1.5" OR 2-2.5 STD DEVIATIONS ABOVE THE NORM.

EXPANDED THE EXCESSIVE RAINFALL RISK AREA FARTHER W INTO THE HIGH
PLAINS OF SERN MT/NW CO GIVEN THE ANTICIPATED BACK-BUILDING LLVL
THETA-E AND HIGH PW AXIS...ALONG WITH THE AFOREMENTIONED ROBUST
AREA OF ENHANCED UPPER AGEOS DIVERGENCE/UPWARD ASCENT.  3 AND 6 HR
FFG VALUES ARE LOWER IN THESE AREAS AS WELL.  THE
MODELS...PARTICULARLY THE HIGH-RES RUNS...CONTINUE TO SHOW SPATIAL
AND TIMING DIFFERENCES WITH THE AXES OF HEAVIEST RAIN (AS EXPECTED
GIVEN THE CONVECTIVE NATURE...EVEN WITH FVRBL...BROAD UPPER
DIVERGENCE).  AS A RESULT...FOR NOW THE EXCESSIVE RAINFALL RISK
REMAINS SLIGHT...THOUGH IT SHOULD BE NOTED THAT THE
SREF/GEFS/ECENS PROBABILITIES OF AREAL-AVERAGE QPF > 2-3" IN 24
HOURS HAS INCREASED AND EXPANDED TOWARD MT/WY WITH THE MOST RECENT
RUNS.


...ALABAMA/GEORGIA...

CANNOT RULE OUT THE POTENTIAL FOR REDEVELOPMENT OF CNVCTV RAINS
LATER TNGT AS A FVBL LLVL MSTR FLUX CONTINUES INTO THE BACKSIDE OF
A MID/UPR LVL COOL POCKET SUPPORTING A REGION OF ISENTROPIC LIFT. 
AT THIS TIME WOULD FAVOR NRN AL AND W CNTRL GA FOR THE MOST
ORGANIZED SHWRS WITH THE MAIN CONCERN BEING THAT SHWRS COULD
REPEAT OVR AREAS SATURATED BY ACTIVITY OVR THE PAST 12 HOURS.


...SRN MINNESOTA...MUCH OF IOWA...AND FAR NW MISSOURI...

AREAS OF HEAVY RAINFALL WILL MOVE INTO THIS REGION PRIOR TO
DAYBREAK THIS MORNING.  THE ACTIVITY IS AHEAD OF A NEWLY-DEVELOPED
MCV...WHICH IS ENHANCING THE UVV'S IN AN AREA WHERE PW'S (~1.5
INCHES) ARE AVERAGING AROUND 2.5 STD DEVIATIONS ABOVE NORMAL.  FOR
FURTHER DETAILS REGARDING THE EXCESSIVE RAINFALL RISK...PLEASE
REFER TO THE MESOSCALE PRECIPITATION DISCUSSION OR FFGMPD
#46...WHICH IS VALID THROUGH 10Z SUNDAY MORNING.

HURLEY