594
AWUS01 KWNH 262047
FFGMPD
NYZ000-PAZ000-WVZ000-OHZ000-270230-
MESOSCALE PRECIPITATION DISCUSSION 0064
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
446 PM EDT THU MAR 26 2026
AREAS AFFECTED...NORTHERN OHIO...WESTERN & CENTRAL PA... SOUTHWEST
NY...
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 262045Z - 270230Z
SUMMARY...SATURATED UPPER-LAYER SOILS/LOW FFG MAY BE LOCALLY
EXCEEDED GIVEN POTENTIAL FOR QUICK BURST THUNDERSTORMS CAPABLE OF
.5-.75"/HR RATES AND LOCALIZED TOTALS OF 1.5-2", ESPECIALLY
IN/NEAR CORRIDOR OR TWO OF REPEATING CELLS.
DISCUSSION...A STRONG 150-180KT 250MB ZONAL JET IS STREAKING
ACROSS THE NORTHERN GREAT LAKES INTO SOUTHERN QUEBEC WITH A SUBTLE
BUT SUFFICIENTLY DIFFLUENT RIGHT EXIT REGION ACROSS THE LOWER
GREAT LAKES THIS AFTERNOON. IN RESPONSE, STRONG SOUTHWESTERLY
WARM-AIR ADVECTION REGIME IS DRAWING HIGHER MOISTURE AND SLIGHTLY
ABOVE NORMAL HIGHER THETA-E AIR ACROSS THE NORTHERN OHIO VALLEY
INTO THE ALLEGHENY PLATEAU. LOW LEVEL FLOW IS SOLID PER VWP WITH
35-45KTS OF 925-850MB FLOW FROM THE SOUTHWEST WITH SUFFICIENT
VEERING THROUGH 700-500MB TO ALLOW FOR A FAIRLY UNIDIRECTIONAL
STEERING FLOW, WITH ALLOWABLE FOR UPSTREAM REDEVELOPING CELLS TO
POTENTIALLY REPEAT ACROSS THE AREA OF CONCERN LATE THIS AFTERNOON
INTO EVENING.
AT THE SURFACE A WELL DEFINED FRONT EXTENDS FROM THE MAIN SURFACE
LOW IN SE IA ACROSS THE SOUTHERN LP OF MICHIGAN WHERE SECONDARY
WEAKER WAVE EXISTS, LIKELY RESPONDING TO THE MID-LEVEL
SHORTWAVE/DIFFLUENCE PATTERN ALOFT. SURFACE MOISTURE CONVERGENCE
IN PROXIMITY TO THE SURFACE FRONT IS FURTHER ENHANCED BY COOLER
LAKE BREEZE AND SHARPER LOW LEVEL TEMPERATURE GRADIENT ALONG THE
SOUTHERN COASTS. THIS ISENTROPIC BOUNDARY IN THE LOW LEVEL FLOW
REGIME WILL SUPPORT ENHANCED MOISTURE CONVERGENCE AT THE
NORTHWESTERN NOSE OF THE MID-LEVEL INSTABILITY POOL UPSTREAM OVER
IL/IN/NW OH. AVAILABLE MOISTURE IS SLIGHTLY ABOVE AVERAGE WITH
TOTAL PWAT VALUES AOA 1.25", THOUGH THE BULK IS BELOW 700MB AND
ANY THUNDERSTORM DEVELOPMENT WILL HELP TO LOAD IN THE LOWER
PROFILES PROVIDING SOME INCREASED RAINFALL POTENTIAL. FORWARD
PROPAGATION WILL BE VERY FAST LIMITING OVERALL DURATION, BUT
HI-RES CAMS INCLUDE RECENT WOFS RUNS SUGGEST ISOLATED BUT BROADER
UPDRAFTS CAPABLE OF THE VERY QUICK BURSTS OF .5-.75" IN 15-30
MINUTES...PARTICULARLY FURTHER WEST AND DEEPER INTO THE MORE
UNSTABLE (1500+ J/KG MUCAPE), HIGHER MOISTURE.
HOWEVER, THE HYDROLOGICAL GROUND CONDITIONS ARE VERY SENSITIVE AS
GREEN-UP IS JUST ABOUT TO START. FFG VALUES ARE BELOW AVERAGE
WITH HOURLY VALUES ABOUT 1" REDUCING TO .5-.75" ACROSS NORTHERN PA
INTO S CENTRAL PA. NASA SPORT LIS PRODUCTS SHOW 0-40CM SATURATION
VALUES OVER 60% INCREASING TO OVER 80% WHERE THE LOWEST FFG VALUE
ARE; SO EVEN LESS VERTICALLY INTENSE SHOWERS/THUNDERSTORMS CAPABLE
OF .25-.5"/HR RATES DOWNSTREAM INTO NY/CENTRAL PA ARE LIKELY TO
SHED NEARLY ALL RAIN TOWARD RUNOFF. THE OVERALL MAGNITUDES AND
COVERAGE ARE LIKELY TO BE LIMITED IN SCOPE AND LOWER END, BUT
STILL POSE A POSSIBLE INCIDENT OR TWO OF FLASH FLOODING. THIS IS
ALSO A CONCERN ACROSS THE LARGER URBAN CENTERS OF NE OH TOWARD
PITTSBURGH METRO LATER THIS EVENING.
GALLINA
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...BGM...BUF...CLE...CTP...ILN...IWX...PBZ...
ATTN...RFC...RHA...TAR...TIR...NWC...
LAT...LON 42667650 42057570 41177590 40477698 40127924
40008191 39968419 40858437 41558200 42068053
42287976 42627812
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