#Philadelphia #weather #PAwx

Some Sunshine on Friday

Posted Thursday 12/28 @ 5:41 PM — It appears that things will clear out enough on Friday that we’ll see some sun. Indeed, a fair amount of sunshine is expected on Friday. (Yes, this is a change in the forecast from yesterday, where clouds were going to remain.)

The upper trough moves over us on Saturday with a reappearance of clouds, at least for a part of the day—

Thursday 9:55 AM —Forecast Review — We had between 1.5″ and 2.7″ of rain in our area over the past day or so. As is almost always the case, the exact areas of the rain maxima were different than any of the model forecasts, but the models gave a good idea of what range of rainfall to expect.

A weather pattern change appears likely around January 4th through 6th. I’ve updated my Winter Outlook.

Tonight Through Friday

Posted Wednesday 12/27 @ 9:49 PM — The heavy rain expected really began in earnest about 8 PM. Some areas to our west have already had significant rainfall.

Here’s the current rainfall (MRMS measured) that fell through 9 PM—

Here’s the additional rainfall expected from now through 6 AM, according to the latest HRRR—

Posted Wednesday 12/27 @ 5:43 PM — Heavy rain and gusty winds are still expected, beginning this evening and tapering before daybreak Thursday. The rainfall totals are still in the general range as shown earlier.

Ordinarily following a storm, clearing moves in, but that’s not the case with the current system. A large upper low is still to our west and clouds and intermittent light showers are possible Thursday and even Friday.

Wednesday Forecast Update

Posted Wednesday 12/27 @ 8:09 AM — Relying on the ECMWF model, it continues to have a bullseye of heavy rain over the Philadelphia area by late evening —

The ECMWF shows rain throughout today of varying intensity, with greatest intensity this evening and overnight.

Total rainfall will be heavy, around 1.5-2″ with locally higher amounts—

The ECMWF also has an area of showers that moves through as late as Thursday afternoon.

Heavy Rain Being Forecast… Again

Posted Tuesday 12/26 @9:09 PM — Tonight’s early models are delaying the heavy rain until Wednesday evening. Rainfall during the daytime will likely be light.

Posted Tuesday 12/26 @ 6:05 PM — It looks like the rain will move in from the west, beginning about 9-11 AM Wednesday morning.

Here’s the NBM blend showing ‘simulated radar’ at 11 AM—

Posted Tuesday 12/26 @ 5:06 PM —As posted this morning, a secondary low is expected to develop off the coast Wednesday. Monday night’s models were leaning towards a much more westward rainfall maxima, but today’s models (and the NBM- model blend) have maintained heavier rainfall in our area for Wednesday.

The latest 18z HREF, HRRR and NAM-NEST are showing fairly heavy rainfall—

I don’t know the exact hydrology situation in our area, but I think the rivers and streams are already on the full side from the heavy rains of about a week ago. If we get this level of rainfall, expect some more flooding.

Forecast Update

Posted Tuesday 12/26 @ 9:15 AM —Last weekend’s forecast had low pressure moving in from the west. Over the past day or so, the models are showing a secondary low will develop off of the coast—

With the secondary low formation, the energy of this system is expected to “jump” over us, possibly reducing the total rainfall in our area on Wednesday.

Several models have backed off considerably on the rainfall in our area, but the latest 12z NBM still shows about 1″ of rain (this may change) —

Additionally, rain that had been expected to begin Tuesday evening is now expected to begin Wednesday morning.

Additional rain possible on Friday.

Week Overview

A low pressure system in the nation’s mid section will move east and spawn a secondary coastal low on Wednesday—

Before that time, we’ll have cloudy conditions, with early fog on Tuesday. Then continued mild, highs 51-53º.

About 0.8 to 1.1″ of rain is expected from Tuesday evening (about 8 PM) through Wednesday.

Thursday will be another mild, transitional day. Windy!

Another coastal low is expected on Friday—

As mentioned in my recently updated Philadelphia Winter & Snow Outlook, a pattern change is strongly signaled for the first week in January— look for much colder and likely stormier weather towards the end of next week.

#Philadelphia #weather #PAwx

Now through Christmas

Updated Thursday 12/21 @ 4:58 PM — Today’s models have backed off considerably on the chance of showers late Saturday evening and Sunday morning. In fact, at this time, most models with the exception of the ECMWF and ICON-EPS have any showers staying well west and far north of the immediate PHL area on Sunday. Considerable cloudiness is still expected.

Posted Thursday 12/21 @ 9:55 AM — A back door cold front will slip through later today with colder air for Friday. The front will return as a warm front on Saturday into Sunday. I’ve summarized the situation in the graphic caption below—

For much of Saturday and Sunday we’ll be in the transition zone between warmer and colder air masses and significant cloudiness is expected. Less certain is the amount of shower activity here.

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Change in Weekend Weather Outlook

Posted Wednesday 12/20 @ 8:25 AM — No, not what you think or want… it’s a warm front that will move through on Saturday. Past models had this frontal passage dry in our area, but the ECMWF and GFS are cranking out some light showers here Saturday night and Sunday morning into afternoon. Considerable cloudiness as well.

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Quiet and Cold

Posted Tuesday 12/19 @ 4:44 PM — A very quiet weather pattern will take over through Christmas day. We’ll be in an upper trough (cold) while much of the country will be under an upper ridge (warm). High pressure at the surface will dominate—

So the this week is a good time for meteorologists in this area to take a vacation. Perhaps a few impulses will move through from the northwest, but nothing major forecast.

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Light Snow Flurries Possible Tuesday Morning

Posted Monday 12/18 @ 7:47 PM — As low pressure continues to move away, a mid level disturbance will rotate through our area around daybreak Tuesday. Several models show scattered snow flurries but temperatures are expected to marginally at or just above freezing. The NBM puts the maximum probability at only 32% and while Canadian models (onboard for the last two flurry events) show nothing.

Here’s what the experimental RRFS is showing at 7 AM—

Considerable low, instability cloudiness mid day and during the early afternoon.

High pressure builds in and fair skies and cold temperatures are expected for much of the rest of the week.

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I’ve updated the Philadelphia Winter & Snow Outlook through Christmas and Dec 30th.

Storm Summary

Posted Monday 12/18 @ 9:52 AM —This should be no news to anyone around here, but we had a generalized heavy 3″-4+” rainfall through this morning. It’s still raining, but I thought I’d post the current rainfall totals through 8 AM this morning—

I don’t think we had the high wind gusts forecast, but another period of windy conditions is expected later this morning into this afternoon, as temperatures drop off.