MESOSCALE PRECIPITATION DISCUSSION 0299
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
226 PM EDT TUE AUG 19 2014
 
AREAS AFFECTED...AZ/SOUTHEASTERN NV/SOUTHWESTERN UT... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 191826Z - 192156Z
 
SUMMARY...HEAVY RAINFALL CONTINUES TO FALL ACROSS CENTRAL AZ WITH
A FOCUS ALONG THE MOGOLLON RIM. GIVEN 1-3" AMOUNTS IN THE PAST FEW
HOURS...ANY ADDITIONAL RAINFALL MAY LEAD TO FLASH FLOODING. THIS
THREAT SHOULD CONTINUE THROUGH THE LATE AFTERNOON BEFORE PWATS
RAPIDLY DECREASE.

DISCUSSION...WIDESPREAD HEAVY PRECIPITATION HAS BEEN OCCURRING
SINCE THE EARLY MORNING HOURS WITH REPORTS OF 2-3" OF RAINFALL IN
THE HIGHER TERRAIN NORTH OF PHOENIX AZ DURING THE PAST THREE
HOURS. THERE SHOULD BE A WINDOW OF ABOUT 3 TO 5 HOURS WHERE HEAVY
RAINFALL IS EXPECTED BEFORE THE BETTER MOISTURE CONTENT LIFTS
NORTHWARD INTO UT. WATER VAPOR IMAGERY AND THE BLENDED TPW-PRODUCT
BOTH SHOW DRIER AIR FILTERING IN AHEAD OF A CLOSED LOW DROPPING
DOWN THE CENTRAL CA COAST. THE 17Z RAP AGREES WITH DRYING THE
TROPOSPHERE BY AROUND 22Z AS PWATS QUICKLY BEGIN TO DROP. UNTIL
THEN...THERE IS STILL PLENTY OF INSTABILITY IN PLACE ACROSS THE
SOUTHERN PORTION OF THE MPD AREA. MUCH OF THE HIGHER CAPE AIR IS
IN WESTERN AZ/EASTERN CA WHERE TEMPERATURES HAVE BEEN ABLE TO SOAR
INTO THE 90S UNDER CLEAR SKIES. RESIDUAL CONVECTIVE CLOUD COVER
ACROSS CENTRAL AZ HAS KEPT LATE MORNING TEMPERATURES ONLY IN THE
UPPER 70S TO LOW 80S. HOWEVER...THE ATMOSPHERIC DYNAMICS ALONE
SHOULD BE ABLE TO KEEP THE ACTIVITY GOING GIVEN STRONG UPPER
DIFFLUENCE AHEAD OF THE CENTRAL CA CLOSED LOW.

HIGH-RESOLUTION GUIDANCE AGREES WITH KEEPING THE HEAVIER
PRECIPITATION CORES ACROSS THE MORE MOUTAINOUS REGIONS. GIVEN THE
COMPLEX TERRAIN IN THE EQUATION...EXPECT THE THREAT FOR FLASH
FLOODING TO PERSIST A FEW MORE HOURS.


RUBIN-OSTER

ATTN...WFO...TWC...FGZ...SLC...PSR...VEF...

ATTN...RFC...CBRFC...CNRFC...

LAT...LON   37981356 38181283 37981231 36901163 36381131 35521018
            34700955 33470933 32630985 32461096 32951199 33801276
            34751318 35941328 37201412 37981356