MESOSCALE PRECIPITATION DISCUSSION 0230
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1037 PM EDT TUE MAY 29 2018

AREAS AFFECTED...NORTHERN AND WESTERN OK...

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 300240Z - 300730Z

SUMMARY...STATIONARY BACKBUILDING ENVIRONMENT LIKELY TO LEAD TO
TRAINING CELLS AND POTENTIAL FOR TWO NARROW CORRIDORS FOR FLASH
FLOODING.

DISCUSSION...UPPER LEVEL SYNOPTIC SETUP IDEAL FOR BACKBUILDING
ENVIRONMENT AS UPPER LOW CONTINUES TO LIFT NORTH ACROSS W SD BUT A
STRONG FAIRLY FLAT 80KT JET REMAINS FAIRLY STATIONARY OVER CO/NM
BORDER BEFORE BECOMING HIGHLY DIFFLUENT ACROSS CENTRAL KS AND OK
LEAVING FAIRLY STATIC BROAD UVV ASCENT WITH SUBTLE SHORTWAVE
PULSES SURGING THROUGH BUT ALSO LEAVING PERSISTENT DPVA (WIND
SPEED ROTOR VORT CENTER FAIRLY STATIONARY OVER THE OK PANHANDLE. 
THIS HAS LEAD TO RAPID EASTWARD PROGRESSION OF THE CONVECTIVE LINE
ACROSS KS BUT AT THE TAIL END WHERE THE DPVA IS STRONGEST...IT
SUPPORTS LOW LEVEL CYCLOGENESIS AND BACKING 850MB FLOW ACROSS OK. 


AT THE SURFACE OUTFLOW BOUNDARY HAS FLATTENED ACROSS NORTHERN OK
WITH A NARROW CORRIDOR OF HIGHLY UNSTABLE BUT MST AS FAR WEST AS
GAGE WITH SFC TDS IN THE MID 60S AND S TO SSELY OF 20 KTS
OVERRUNNING THE BOUNDARY.  AS SUCH STRONG MST CONVERGENCE/UPGLIDE
ALLOWS FOR ADDITIONAL UPDRAFT DEVELOPMENT AND GIVEN UPPER LEVEL
SUPPORT MAINTENANCE.  ALSO SOUTH OF THE AXIS OF DIVERGENT
FLOW...CLOUD BEARING FLOW IS JUST SOUTH OF EAST FAIRLY PARALLEL TO
THE OUTFLOW BOUNDARY ALLOWING FOR A TRAINING CORRIDOR.  WHILE THE
MID-LEVEL ENVIRONMENT SUPPORTS SEVERE HAIL...KDP FROM VNX RADAR
SUGGESTS HAIL IS BEING ACCOMPANIED WITH HVY RAINFALL AND WITH
SATURATING LOW LEVEL PROFILES, EFFICIENCY OF RAINFALL PRODUCTION
WILL BE INCREASING. AS SUCH TRAINING OF 1.5-2"/HR RAIN RATES POSE
FF THREAT GIVEN VERY SLOW EXPECTED EASTWARD SHIFT OF THE
BACKBUILDING GENERATION AREA THROUGH 06Z.  2-4" TOTALS ARE
POSSIBLE AND EVEN THOUGH GROUND CONDITIONS ARE FAIRLY DRY...THIS
MAY STILL EXCEED FFG VALUES AND SUGGEST FLASH FLOODING ESPECIALLY
IN LOCALIZED AREAS WHERE CELLS (DUE TO STRONG SUPERCELL ROTATION)
SLOW FORWARD PROGRESS INCREASING DURATION LOCALLY BUT ALSO
POTENTIALLY LEADING TO CELL MERGERS.

AN ISOLATED BUT GROWING COMPLEX UNENCUMBERED BY OTHER CONVECTION
SOUTH OF IT HAS EVEN GREATER POTENTIAL FOR SUPERCELL/SLOW EASTWARD
PROGRESSION..BETTER MOISTURE FLUX AND AREA TO DRAW FROM.  A DRY
LINE BULGE DENOTED BY CDS VEERING TO SW AND DRYING...LEADS TO
FURTHER INCREASED LOW LEVEL FLOW ACCELERATION DUE TO SLIGHTLY
TIGHTENED PRESSURE GRADIENT.  SIMILAR 2-4" TOTALS ARE POSSIBLE
BEFORE LLJ VEER WITH DIURNAL INERTIAL ROTATION TOWARD 03-04Z
SUPPORTING GREATER EASTWARD PROPAGATION VECTORS.  AGAIN
HERE...FLASH FLOODING IS CONSIDERED IS POSSIBLE. 

BETWEEN THE TWO COMPLEXES FROM ELLIS/ROGER MILLS TO LOGAN TO
OKLAHOMA COUNTIES WILL LIKELY REMAIN DRY.   
GALLINA

ATTN...WFO...OUN...TSA...

ATTN...RFC...ABRFC...

LAT...LON   36999808 36819583 36229552 35729588 35819732
            35859773 35969853 35769875 35459809 35379769
            35209704 34859707 34599750 34779884 35059984
            35599991 35669925 35849880 36149928 36269957
            36679960 36949921