320
AWUS01 KWNH 112200
FFGMPD
CTZ000-NYZ000-NJZ000-PAZ000-120200-
MESOSCALE PRECIPITATION DISCUSSION 1012
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
559 PM EDT TUE AUG 11 2026
AREAS AFFECTED...NORTHEAST PA...NORTHERN NJ...FAR SOUTHERN NY
INCLUDING NYC...
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY
VALID 112200Z - 120200Z
SUMMARY...FEW SCATTERED THUNDERSTORMS ORIENTED FOR POSSIBLE
REPEATING BUT CROSSING SATURATED SOIL CONDITIONS AND URBAN ZONE
MAY RESULT IN LOCALIZED 2-3" TOTALS AND POSSIBLE FLASH FLOODING
CONDITIONS THROUGH EARLY OVERNIGHT.
DISCUSSION...GOES-E VISIBLE AND REGIONAL RADAR MOSAIC SHOWS
SCATTERED CONVECTIVE DEVELOPMENT ACROSS NORTHEAST PA INTO NORTHERN
NJ. A WEAK SURFACE LOW CAN BE ANALYZED NEAR KPOU ALONG A WELL
DEFINED SURFACE STATIONARY FRONT THAT SEPARATES HIGHER TDS AIR
(LOW 70S) TO THE SOUTH AND LOW 60S TO EVEN SOME MID TO UPPER 50S
ACROSS UPSTATE NY. THE CORE OF A 110KT JET IS SKIRTING NORTH OF
THE AREA PROVIDING SOME WEAK DIVERGENCE ALOFT, BUT ALSO SUPPORTING
LOW LEVEL FGEN STRENGTHENING ACROSS THE NY/PA LINE PROVIDING
SUFFICIENT DEEP LAYER MOISTURE CONVERGENCE ALONG THE TIGHTENING
PWAT GRADIENT IN THE AREA. SURFACE TO 850MB CYCLONIC CURVATURE
ACROSS THE POCONOS INTO CATSKILLS EVEN AT 15KTS HAS BEEN
SUFFICIENT TO PROVIDE ASCENT ON CONDITIONALLY UNSTABLE AIR MASS
WITH 2000-2500 J/KG OF SBCAPE. SOLID 35-40KT EFFECTIVE BULK
SHEAR ALONG WITH RADAR TRENDS SUGGESTS SOME WEAK ROTATION IN THE
SCATTERED CELLS TO FURTHER ENHANCE LOW LEVEL MOISTURE FLUX
CONVERGENCE. RAP TPW ANALYSIS SHOWS A BULGE NOSING NORTHEASTWARD
THROUGH N NJ WITH 1.75-1.9" VALUES TO FEED THE STRENGTHENING
UPDRAFTS. CURRENTLY CORES ARE FAIRLY NARROW BUT ARE BROADENING
WITH TIME, LIKELY TO SUPPORT 1.75-2"/HR RATES SOON. WHILE MEAN
STEERING FLOW IS 30-40KTS, THE FLOW IS PARALLEL TO THE BOUNDARY
AND THE ORIENTATION OF THE CURRENT DEVELOPMENT, SUGGESTIVE OF
POSSIBLE REPEATING/TRAINING THROUGH THE LATE EVENING HOURS.
THIS IS A CONCERN GIVEN RECENT HEAVY RAINFALL AND SATURATED UPPER
SOIL PROFILES PER NASA SPORT WITH 0-40CM RATIOS IN TO THE UPPER
60S/LOWER 70S REACHING 90TH PERCENTILES FOR THIS TIME OF YEAR. AS
SUCH FFG VALUES ARE HIGHLY VARIABLE, BUT SPOTS LESS THAN 1"/HR
EXIST ACROSS N NJ, WITH MUCH OF THE AREA AT OR BELOW 2"/HR.
ADDITIONALLY, BROAD URBAN AREA INTO NYC WOULD NATURALLY BE PRONE
TO INTENSE RATES. WHILE SLIGHT SOUTHWARD PROPAGATION IS EXPECTED
AND MAY HELP TO DEFLECT PROLONGED REPEATING, OVERALL TOTALS OF
2-3" CAN BE EXPECTED ACROSS THE AREA OF CONCERN AND WITH LOW FFG
VALUES, LOCALIZED INCIDENTS OF FLASH FLOODING ARE CONSIDERED
LIKELY.
GALLINA
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...BGM...CTP...OKX...PHI...
ATTN...RFC...RHA...TAR...NWC...
LAT...LON 41537662 41537580 41377398 41037330 40647333
40477388 40247394 40027401 40177473 40647580
41257661
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