MESOSCALE PRECIPITATION DISCUSSION 0379
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
740 PM EDT THU JUL 23 2015
 
AREAS AFFECTED...NORTH DAKOTA....FAR NORTHWEST MINNESOTA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 232339Z - 240539Z
 
SUMMARY...LEAD AREA OF SLOW MOVING SOUTHWARD PROPAGATING
CONVECTION LEADING TO MERGERS FROM EASTWARD MOVING CONVECTION FOR
POSSIBLE FLASH FLOODING LATER THIS EVENING.

DISCUSSION...DEEP NORTH TO SOUTH CORRIDOR OF ENHANCED LOW LEVEL
FLOW WITH 25-30 KTS WINDS LINE UP WELL WITH CU FIELD IN VISIBLE
IMAGERY. THIS EVENTUALLY INTERSECTS WITH A LARGE CONVECTIVE
COMPLEX ACROSS SOUTHERN MANITOBA THAT IS DEVELOPING SOUTHWARD AT
THE APEX OF THE 1000-500 THICKNESS RIDGE...AT 5 KTS PER RAP
ANALYSIS PROPAGATION VECTORS.  HI-RES MODELS HAVE BEEN HAVING A
HARD TIME INDICATING THIS SOUTHWARD MOTION OF THE COMPLEX AND
FOCUSED ON THE WESTERN ND SEVERE CONVECTION ALONG THE COLD
FRONT...WHICH HAS BEEN HANDLED MUCH BETTER.   HI-RES MODELS HAVE
BEEN PAINTING SWATHS OF 1-3" WITH THE CONVECTION AS IT MOVES
EASTWARD BUT ADDITIONAL RAIN FROM MERGERS AND INCLUDING THE
1-2"/HR RATES LIKELY WITH THIS COMPLEX SHOULD COMPOUND THESE
TOTALS FOR 2-5" PARTICULARLY ACROSS NORTHEAST ND. 

CURRENT CONVECTION FROM CWEI TO KHZE IS IMPRESSIVE ON IR/VIS HAS
LAID OUT A WELL DEFINED OUTFLOW BOUNDARY PER MBX RADAR THAT IS
ACTING AS AN EFFECTIVE ISENTROPIC BOUNDARY FOR ELEVATED
CONVECTION.  EXCELLENT LOW LEVEL MOISTURE THOUGH STEEP LAPSE RATES
HAS REDUCED RAINFALL EFFICIENCY IN THE NEAR TERM TOWARD HAIL AND
COLD POOL/OUTFLOW GENERATION. INITIALLY CELL MOTIONS ARE SLOW WITH
WEAKENED UPPER LEVEL FLOW BETWEEN DUAL JET STRUCTURE.  THIS LEADS
TO INCREASES ISALLOBARIC FLOWS FROM THE PRESSURE FALLS OVER
WESTERN ND REDUCING CELL MOTIONS EVEN FURTHER (TO NEAR STATIONARY)
ALLOWING FOR MOISTENING OF THE PROFILES TO INCREASE EFFICIENCIES
WITH RATES OF UP TO 1.5"/HR COMPOUNDING INTO 2-3" TOTALS.   THIS
SHOULD REMAIN FOR AN HOUR TO TWO LONGER BEFORE UPPER LEVEL FLOW
FROM APPROACHING JET INCREASES AND CELLS BEGIN TO MOVE
EASTWARD...BEFORE THE MERGERS ACROSS EASTERN ND TOWARD 03-05Z.

GALLINA

ATTN...WFO...ABR...BIS...FGF...

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

LAT...LON   49009933 49009724 48869563 46849633 45679684 
            45729882 46709933 46910032 47180145 47500195 
            48300196 48890129 48960070