Updated Mon 08:41 AM — Latest HRRR model forecast for Fort Washington/Blue Bell:

Lull in the rainfall about 11 AM, then thunderstorms move through:

Peak wind gusts expected  12-2 PM:

Click on image for larger view:

7 AM HRRR model forecast Winds, Gusts, PRATE (Precipitation rate)

WEATHER UPDATE

Somewhat good news: Last night’s GFS has brought the wind gust forecast to a generalized 60 mph, with these levels occurring around noontime.  (None of those 80 mph levels.)   The most recent HRRR is still in the 68 mph wind gust range with similar peak timing.  The NAM-NEST has backed off to the 56 mph range.

(Wind gusts is a parameter that models aren’t really the best at getting right. So the gust forecast shouldn’t be taken as literally as temperature forecasts.)

There is expected to be a line of thunderstorms developing ahead of a cold front. This line of thunderstorms is expected  about 1-3 PM. (Blue Bell). Rain tapers after the frontal passage around 4-6 PM.

MONDAY WIND GUST UPDATE

Brief Update Sun 10 PM—  The latest short-range high resolution models are just becoming available based on the most recent upper air measurements done at 8 PM EDT tonight.

Based on the HRRR (High Resolution Rapid Refresh), the highest wind gusts will be around 1PM Monday.  Here is the latest —

00Z HRRR Wind Gust forecast for 1 PM Monday  (click on image for larger view)
HRRR Wind Pressure  (click on image for larger view)

Gusts over 45 as early as 6AM.

Winds and wind gusts are difficult to forecast accurately, but I haven’t seen model numbers like this in a long time.

Latest rain accumulation is 2+ inches or rain.

Stay tuned; I’ll update early Monday morning.