FOUS30 KWBC 211839

QPFERD



Excessive Rainfall Discussion

NWS Weather Prediction Center College Park MD

239 PM EDT Sat Mar 21 2026



Day 1

Valid 16Z Sat Mar 21 2026 - 12Z Sun Mar 22 2026



The probability of rainfall exceeding flash flood guidance is less

than 5 percent.



Orrison





Day 2

Valid 12Z Sun Mar 22 2026 - 12Z Mon Mar 23 2026



...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS

OF THE NORTHERN APPALACHIANS EASTWARD TO NEW JERSEY AND SOUTHERN

NEW YORK STATE...



Latest guidance (including CAMs) depict scattered thunderstorms

developing in only a modestly moist airmass for heavy rainfall

(around 1 inch PW) and fast storm speeds from strong westerly flow

aloft. The storms will, however, form along an initiating boundary

oriented parallel to westerly flow aloft, supporting areas of

localized training. Areas of 1-2 inch rainfall totals are expected,

and some of that rain could fall in a short timeframe (<3 hours).

Given low FFG, some potential for deep convection in urban areas 

(Philadelphia to New York City), and locally sensitive locales in 

southwestern Pennsylvania/far northern West Virginia, introduced 

low/Marginal probabilties for excessive runoff.



Cook





Day 3

Valid 12Z Mon Mar 23 2026 - 12Z Tue Mar 24 2026



The probability of rainfall exceeding flash flood guidance is less

than 5 percent.



Cook/Roth





Day 1 threat area: https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt

Day 2 threat area: https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt

Day 3 threat area: https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt