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Friday and Weekend Preview

Updated Fri 09/29 @ 9:36 AM — For the immediate Philadelphia area, cloudy with light scattered showers today. The models continue with most of the rain east of the Pennsylvania – New Jersey border. It doesn’t look promising for the Phillies game tonight in NY, but who knows, maybe they’ll play in the rain.

NBM hourly rain forecast for tonight at 7PM—

As for Saturday, it looks like some showers still possible in the morning with low clouds hanging in for much of the day. Maybe some breaks in the clouds towards evening.

Sunday still looks quite nice!

My regular Weekend Weather Forecast will be posted later today.

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Friday Forecast Update

Updated Thu 09/28 @ 9:59 PM — Tonight’s latest NBM (00z) continues with a steep gradient in forecast rainfall for tonight into late Friday night.

There has been consistency with the forecasts, but some models (the HREF) has the 1″ rainfall totals a bit further westward, while the Canadian models are showing somewhat less rainfall overall. I’m going to hang my hat on the NBM—

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Friday Outlook and Weekend Preview

Updated Thu 09/28 @ 5:17 PM — As mentioned this morning, the axis of heavy rain is trending further eastward and that trend continues with today’s 18z NBM—

Saturday’s weather includes showers in the early morning, ending before noontime. We’ll see sunshine in the afternoon.

Sunday looks to be quite nice with highs in the 70s.

Next week looks to be nice and much warmer with temperatures approaching 80º

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Thursday-Friday Forecast Fine Tune

Updated Thu 09/28 @ 9:46 AM — My earlier posted forecast violated the cardinal rule of weather forecasting:

“Always walk outside or put your hand out the window before making a forecast”

A light mist has developed in the immediate Philadelphia area, not really showing on radar, indistinguishable from background noise.

The latest NBM (12z), just available, shows the possibility of light mist/drizzle as early as NOW.

So Thursday looks damper and somewhat wetter than previously forecast.

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Updated Thu 09/28 @ 9:04 AM — It appears that Thursday will be just cloudy. While the latest NBM still has some light scattered sprinkles as early as 5-8 PM, any rain in the immediate Philadelphia area will probably wait for 11 PM to midnight.

While Friday is definitely going to be cloudy with low clouds and drizzle, there are varying forecasts for the amount of rain west of the Delaware river. The NBM has a fair amount of rain making it into Philadelphia, but the HRDPS has minimal amounts. All models have most of the rain in NJ, especially northern NJ and the trend has been increasingly eastward for the main rain axis.

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Thursday – Friday Weather Outlook

Updated Wed 09/27 @ 9:20 PM — An area of low pressure is developing in the same region as Ophelia had formed. The upper air flow is different this time around and this low is expected to brush our area with rain late Thursday into Friday as it moves out to sea. Additional support to this low will be provided by an upper low pressure system over the Great Lakes.

Here’s the current water vapor image at 9 PM tonight—

For Thursday, sunny very early, then increasing low cloudiness. Cloudy by the afternoon. Light scattered rain develops between 5 PM and 9 PM, moving in from the southeast.

Friday will be a dark, cloudy day with light drizzle and light showers.

The weekend looks better, especially Sunday.

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Wednesday and the Remainder of the Week Outlook

Updated Tue 09/26 @ 4:54 PM — Today was yet another day of dark skies and drizzle and occasional rain. The radar image taken earlier this today captures the flow—

Wednesday is looking dry, but still with considerable cloudiness. There should be some breaks of sun, especially northern suburbs.

Another coastal system will affect us late Thursday into Friday. A developing inverted coastal trough will bring rain on Friday, especially areas in NJ—

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Tuesday Update

Update Mon 9/25 10:39 PM — Tonight’s models are suggesting that Tuesday’s weather will be more similar to Monday’s than previously thought. The NAM-NEST and HIRESW show low clouds, drizzle and showers, only tapering late afternoon. Additional rain accumulations expected, about 0.25 to 0.33”

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Tuesday Outlook

Updated Mon 09/25 @ 5:31 PM —Monday was ‘dark with low clouds, drizzle and some scattered showers’ as forecast. Unfortunately, Tuesday’s weather is looking only slightly less dark. Plenty of low clouds and additional widely scattered showers and drizzle expected, but the areal coverage of the showers and drizzle lessens during the afternoon.

Here’s the latest NBM forecast showing clouds and drizzle/showers at 11 AM—

There may be some brighter skies at times, but things really don’t improve until Wednesday.

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Monday Update

Updated Mon 09/25 @ 10:46 AM — We got a lot of rain this weekend. More dreary conditions expected today, but with much less additional rainfall.

How much rain did we get so far?

How much additional rainfall is forecast for today?

Here’s the latest NBM forecast rainfall for Monday —

Monday

What was once a strong low pressure system in all levels of the atmosphere, the remnants of Ophelia will be a weak, closed mid-level (500 mb) low on Monday—

This low will gradually dissipate, but considerable low level moisture and a mid level cyclonic flow will result in dark, low clouds, drizzle and some scattered showers on Monday. No sunshine is expected.

Tuesday through Friday

We may begin to see some sunshine on Tuesday, but still with a chance of widely scattered sprinkles.

As for the rest of the week, we’ll be influenced by an upper level closed low that will keep us cooler than seasonal averages—

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Tropical Storm Ophelia

Updated Fri 09/22 @ 4:39 PM — When I updated this site this morning, the storm that is forecast to affect our weekend was still referred to as Atlantic tropical depression 16. It’s been named Ophelia My regular “Weekend Weather Forecast” will cover this storm and its impact on our area.

Look for a new post shortly.

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Update Fri 9/22 8:38 AM — A quick update. No significant changes from last night’s forecast. Rain moves in from the southeast between 2AM and 4AM. Very windy with wind gusts 38-46 mph. Heavy rain on Saturday, especially Saturday late morning. Rain continues through much of Sunday. Total rainfall by Sunday evening 2-3.5”

Updates later today.

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Update Thu 9/21 9:30 PM — The latest NAEFS ( a combination of our GEFS and the Canadian ensemble models) captures the current consensus guidance for this storm—

By Sunday, 24 hours later, the surface low has filled and weakened and the upper level low lingers. It’s still raining here—

The latest NBM model just available show rainfall of 2-3” by Sunday evening and wind gusts of 35-45 mph.

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Update Thu 9/21 5:03 PM — This will a difficult forecast to get right. The model guidance is all over the map…literally. Most models now have the strong tropical low pressure moving inland. Most, but not all, have this surface low pressure system rapidly “filling” as it encounters blocking high pressure, leaving a closed upper low. Most models have about 1.5-3” of rain through Sunday, with the majority of the rain Saturday. Heaviest activity closer to the shore is a safe, but not necessarily accurate emphasis.

It’s going to be difficult to pin down specifics regarding locations of the heaviest rains and higher winds. Stay tuned

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Update Thu 9/21 8:29 AM — Last night’s ECMWF has finally joined our GFS model with a more coastal track and with the low pressure system becoming quasi-stationary as it moves over southern Delaware. The system will encounter high pressure to our north and will stall and somewhat “fill” (weaken).

High winds and heavy rains still likely with this system.

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Update Wed 9/20 9:52 PM — This afternoon’s ECMWF and NAEFS models, just available, have become a bit more similar, with the storm either moving a bit eastward, or slower just to our south. This trend would reduce the impact of the storm in our immediate area. Will have to see the trends with tonight’s models to get a better handle on this system.

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Previously Posted Wed 9:02 PM —

As mentioned over past days, a disturbance off of the Atlantic coast of Florida will develop into an intense coastal low with some tropical characteristics. It’s expected to begin to affect our area during the predawn hours of Saturday morning.

The majority of models have this system moving up the coastline, with the exception of the ECMWF, which continues to have the system bend away from the mid Atlantic coast. (Tonight’s GEFS does have the storm blocked from northward movement as it approaches the Delaware coast with a slight turn eastward. This somewhat supports the ECMWF track, but it’s too soon to hang our hats on this forecast.)

Heavy rain, high winds are likely on Saturday if it follows the track of the GFS, Canadian and German ICON models. Rainfall totals of 1.5 to 3 inches are likely, with wind gusts 35-50 mph. Impacts will be significantly less if it follows the ECMWF track.

Here’s the latest Canadian RGEM —

So, this could be a major storm for our area or it might move eastward enough to significantly reduce its impact. Stay tuned.

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