286
AWUS01 KWNH 212235
FFGMPD
AZZ000-220234-
MESOSCALE PRECIPITATION DISCUSSION 0993
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
635 PM EDT SUN OCT 21 2018
AREAS AFFECTED...SOUTHERN ARIZONA
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 212234Z - 220234Z
SUMMARY...THUNDERSTORMS CAPABLE OF PRODUCING HOURLY TOTALS OF 1-2"
WILL BE POSSIBLE ACROSS FAR SOUTHERN ARIZONA THROUGH LATE
AFTERNOON AND EARLY EVENING.
DISCUSSION...IN DIVERGENT FLOW ALOFT WITH AN OPEN WAVE ACROSS
SOUTHERN CALIFORNIA, COMBINED WITH PEAK HEATING WHERE INSTABILITY
IS AROUND 1500-2000 J/KG, THUNDERSTORMS HAVE DEVELOPED ACROSS
SOUTHERN ARIZONA. RECENT ANALYSIS SHOWS A TONGUE OF HIGHER PWATS
(1-1.1") ACROSS THE AREA, WHICH IS IN THE 90TH PERCENTILE AND
ROUGHLY 1-2 SD ABOVE NORMAL. CONVECTION HAS BEEN DRIFTING
NORTHEASTWARD PER LATEST KEMX RETURNS, WHERE HOURLY RATES HAVE
EXCEEDED 1-2".
HI-RES MODELS HAVE NOT HANDLED THIS ACTIVITY WELL, BUT WOULD
EXPECT A SLOW PROGRESSION NORTHEAST FOR THE NEXT FEW HOURS UNTIL
PEAK HEATING/INSTABILITY WANES. ADDITIONAL TOTALS OF 1-2", WITH
LOCALLY HIGHER AMOUNTS, WILL BE POSSIBLE OVER AREAS WITH LOWER FFG
(1-HR 1" OR LESS) WHICH MAY LEAD TO LOCALIZED FLASH FLOODING.
TAYLOR
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...PSR...TWC...
ATTN...RFC...CBRFC...
LAT...LON 33470983 32030947 30711000 30381073 31521201
33041100
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page