MESOSCALE PRECIPITATION DISCUSSION 0402
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
821 PM EDT TUE SEP 30 2014
 
AREAS AFFECTED...EASTERN KANSAS...SOUTHEAST NEBRASKA...NORTHWEST
MISSOURI...SOUTHWEST IOWA... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 010020Z - 010420Z
 
SUMMARY...MULTICELLULAR CONVECTION WILL BECOME BETTER ORGANIZED
THIS EVENING...THEN BEGIN TO BACK BUILD AND TRAIN OVER THE SAME
AREAS TOWARD MIDNIGHT.

DISCUSSION...A DEEP MID AND UPPER LEVEL CYCLONE LIFTING INTO THE
NORTHERN PLAINS IS ACCOMPANIED BY MULTIPLE SLOW MOVING FRONTAL
FEATURES AT THE SURFACE ACROSS THE CENTRAL PLAINS AND LOWER
MISSOURI VALLEY. STRENGTHENING LOW-LEVEL INFLOW AHEAD OF THE SLOW
MOVING COLD FRONT THIS EVENING (850 MB FLOW INCREASING TO 30+
KNOTS BY 04Z) WILL INCREASE THE POSITIVE THETA-E ADVECTION AND
MOISTURE TRANSPORT INTO THE WARM/STATIONARY FRONTAL ZONE ACROSS
SOUTHWEST IOWA AND NORTHERN MISSOURI...WHILE ALSO FAVORING MORE
UPWIND PROPAGATION AND THUS TRAINING OF CONVECTION WITH TIME. 

THE AMPLIFIED UPPER LEVEL PATTERN AND (THUS) PROLONGED PERIOD OF
FAVORED UPPER LEVEL DIFFLUENCE/DIVERGENCE WILL SUPPORT CONTINUED
REGENERATION OF CONVECTION ACROSS THE OUTLOOK AREA -- RESEMBLING A
"MADDOX SYNOPTIC" TYPE SETUP FOR HEAVY RAINFALL. THE CONVECTION
WILL BE ABLE TO TAP A MODERATELY FAVORABLE THERMODYNAMIC
ENVIRONMENT FOR LATE SEPTEMBER AS MUCAPES CONTINUE AROUND 500-1000
J/KG WHILE PRECIPITABLE WATER INDICES CLIMB TO AROUND 1.5 INCHES.
CONSIDERING THIS AND THE RELATIVELY LOW FLASH FLOOD GUIDANCE
ACROSS THE AREA...RAINFALL RATES OF 2-3+ INCHES WITHIN 3 HOURS MAY
RESULT IN FLASH FLOODING IN AREAS WERE THE CELLS TRAIN. IN TERMS
OF THE LATEST MESOSCALE GUIDANCE...THE MAJORITY OF THE 4KM MODELS
ARE NOT HANDLING THE CURRENT AREA OF CONVECTION ACROSS THE AREA
VERY WELL... THOUGH BY COMPARISON IT WOULD APPEAR THE NSSL WRF AND
SPC WRF ARE VERIFYING SOMEWHAT BETTER WITH THE QPF THROUGH 00Z.
GIVEN THIS AND SOME OF THE RADAR ESTIMATES THUS FAR ACROSS
SOUTHEAST NEBRASKA...LOCALIZED AMOUNTS OF 3-5+ INCHES ARE
ANTICIPATED WITHIN THE OUTLOOK AREA.

HURLEY

ATTN...WFO...DMX...EAX...ICT...LSX...OAX...TOP...

ATTN...RFC...ABRFC...MBRFC...NCRFC...

LAT...LON   42129486 41349382 39249234 38209619 38249723 
            38929749 40429648