Category Archives: Weather Outlook


Updated Mon 10/03 12:43 PM — Latest models continue to show periods of heavy rain through part of Wednesday. Total additional rain accumulation is coming in at 1.5-3” in the immediate PHL area with the upper range favored.

Posted Mon 8:56 AM

Tropical systems and their remnants often change the weather pattern and such is the case with Ian, where we’ve gone from a near drought situation to over a month’s worth of rain in a few days.

Here’s the past 72 hour rain accumulation, according to the MRMS

MRMS rain accumulation for prior 72 hours. Color code is in inches, contours are in mm (25.4mm =1 inch) (Click on image for a larger view.)

The current weather in the upper atmosphere is best captured by the satellite water vapor image—

Water Vapor Image 8AM Monday with superimposed radar and RAP model 250 mb (jet stream) wind flows (orange) Upper low in western PA is spawning coastal low off of Virginia coast. (Click on image for a larger view.)

An upper low, the remnants of what was Hurricane Ian, is to our west. It’s energy is being transferred to a secondary coastal low that will be slow to move.

06z GFS forecast for early morning Tuesday. Upper low moves to Virginia and coastal low deepens. Until the upper low catches up with the surface low to its east, the system won’t move. (Click on image for a larger view.)

Significant moisture in the system will be thrown back towards us over the next two-three days in the form of heavy rain.

Several models show several additional inches of rain possible in some areas on Tuesday, although the trend with some models is for the heaviest rain now to be to our west.

Last night’s models had the rain stopping for the immediate PHL area today. The 06z GFS continues with some rain for today, Monday, becoming heavy after midnight, with a soaking rain on Tuesday.

Many models have the system departing on Wednesday, but it may be slow to do so. Exact timing with such systems is tough. Stay tuned.


Hurricane Ian has its own web page. Click here.

Update Fri 09/30 @ 8:55 AM —Updated the Tropical Storm Ian page with weekend outlook and change in timing and amount of rain.

Update Tue 09/27 @ 6:08 PM — (Updated Hurricane Ian page) We continue to be a northerly flow of dry air through Friday. We may begin to see some high clouds associated with Ian Friday.

The latest ECMWF shows some rain for us by Saturday afternoon from Ian.

Latest ECMWF forecast for Saturday at 2 PM. Rain moves in from Ian. (Click on image for a larger view.)

Posted Mon 9:32 PM

Our weather this week will be influenced by an upper air trough bringing continued cooler, temperatures. Current seasonal average highs are 70-72º. We’ll be seeing upper 60s over the next two days.

Water Vapor image shows jet stream level winds and the position of upper level systems. The trough over the eastern part of the country will combine with a southerly flow over the Carolinas and Georgia to influence the movement of Hurricane Ian. (Click on image for a larger view.)

This corresponds to the current depiction of the NAEFS

NAEFS current conditions Monday evening (Click on image for a larger view.)

The remnants of Hurricane Ian will affect us later in the week and more likely, during the weekend. I’ll be following the models.

Current indications, based on the GFS, ECMWF and ICON models, suggest that the bulk of the rain associated with this storm will move just to our south late Saturday into Sunday. With hurricanes, anything can happen and changes are likely. Stay tuned


Weekend Forecast- Early Outlook

Update Fri 09/23 @ 9:37 AM — High pressure will build in Friday and be with us through Saturday. Low pressure near the Great Lakes will move eastward on Sunday.

Beautiful weather for Saturday.

Sunday looks to be mostly cloudy in the morning becoming cloudy by late morning. There’s a chance of some light scattered showers as early as 4 PM, but most models have the showers/rain waiting until evening.

The uncertainty is best shown as a rain probability for Sunday at 5 PM —

Tooday’s latest 12z NBM 1 hour rain probability at 5 PM Sunday. Anything greater than 20% (green–>yellow) in a is a reasonable chance of rain in a 1 hour time frame. (Click on image for a larger view.)

My regular Weekend Weather Forecast will be posted later this afternoon.

Updated Thu 9/22 6:41 PM — Latest GFS has a change in the forecast for the weekend. Originally, the entire weekend was going to be quite nice. It appears that a warm front will bring some showers and clouds on Sunday. More info tomorrow.

Models over-forecast the rain

Update Thu 09/22 @ 6:17 PM — The models over-predicted the amount of rain here today.

Here’s what actually fell, according the the MRMS—

Total Rainfall on Thursday based on the MRMS. A few areas (blue shading) had about 0.35 inches. Most did not. (Click on image for a larger view.)

Some Rain mid-day Thursday

Update Wed 09/21 @ 7:57 PM — Latest models are fairly consistent with previous forecasts. Rain, maybe even a thundershower, beginning mid to late morning Thursday and ending in the 1 PM-3 PM time frame.

Maximum total precipitation, according to the NBM, is about 0.1-0.3 inches of water—

Today’s 19z NBM forecast for Thursday at 11 PM (precipitation and winds) (Click on image for a larger view.)

Friday, windy and autumnal. The weekend looks very nice!

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