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Philadelphia Weekend Weather and Storm Forecasts
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Fri, 28 Mar 2014
Philadelphia Weekend Weather Forecast - Fri PM
A closing off upper air low-pressure system will induce a surface low to form directly over us during the weekend. The combined upper low and surface low pressure system will be slow to move and will bring periods of rain, sometimes heavy, over the weekend. It's rare to see POPS at 100% for several periods in the model output statistics but the current GFS MOS has 36 hours of 100% precipitation probability!
So the strange weather continues...
Sat 3/29: Cloudy in the morning with rain developing by afternoon. High 54
Sun 3/30: Cloudy and stormy with rain, possibly heavy. Windy. High 56.
posted: Mar 28 2014 at 3:49 pm
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Fri, 21 Mar 2014Philadelphia Weekend Weather Forecast - Fri PM
A weak cold front moves through Saturday morning, with clouds and maybe a light sprinkle. Skies partially clear in the afternoon.
Another reinforcing front passes through early Sunday morning with more clouds and cooler temperatures. (Average high temp is 56.)
Sat 3/22: Cloudy in the morning, Breezy. Chance of a quick sprinkle. Partly sunny in the afternoon. High 65.
Sun 3/23: Considerable cloudiness in the morning. Skies clear during the afternoon. Much cooler. High 46.
posted: Mar 21 2014 at 7:17 pm
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Sun, 16 Mar 2014Philly Winter Weather Update - Sun 10 PM
The latest NAM shows 3-4 inches of snow from the very southern part of Philadelphia with more further south. There is a drop-off of snow even over short distances to Willow Grove, where an inch or so is possible. This storm is similar to the one of two weeks ago, where the northern suburbs got little and Delaware/South Jersey had several inches.
Snow ends during the early morning.
.
posted: Mar 16 2014 at 10:18 pm
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Philly Winter Weather Update - Sun 11 AM
The latest NAM has flipped again to about 3 inches of snow from the very southern part of Philadelphia southward. There is a sharp cut-off of snow even in the short distant to Northeast Philadelphia and Chestnut Hill. This storm is similar to the one of exactly two weeks ago, where the northern suburbs got little if anything and Delaware/South Jersey had several inches. Like that storm, there were changes in the position of the boundary between dry cold and moisture as little as 12 hours before the event. So additional changes in the forecast storm are possible.
Stay tuned for any changes about this time tonight.
posted: Mar 16 2014 at 10:55 am
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Sat, 15 Mar 2014Philly Winter Weather Update - Sat 11 PM
The latest NAM again suppresses the snow to south of Philadelphia. So now, it appears it will miss us.
Stay tuned for any changes.
posted: Mar 15 2014 at 11:00 pm
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Philly Winter Weather Update - Sat 6 PM
The models have been less than consistent predicting the possible snow for Monday. This morning's NAM model kept the snow to our south. This afternoon's NAM and GFS both show snow, starting Sunday night and ending by noon on Monday. Both models now show about 0.40 inches water with very cold temperatures. It's likely that there will be 3-4 inches of snow by Monday morning. Accumulations in March are tough to predict because the insolation through the clouds can allow melting on roadways during the day.
Despite what I'm hearing right this moment on Channel 10, this won't be "wintery mix" This will fall as snow. How much is still uncertain.
posted: Mar 15 2014 at 6:22 pm
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Fri, 14 Mar 2014Philadelphia Weekend Weather Forecast - Fri PM
A weak upper air disturbance will move through Friday evening, perhaps with some light sprinkles. Skies clear Saturday, as a westerly flow of air comes in. Temperatures will drop as the winds become more northerly later Saturday and Sunday. An approaching low pressure system from the south will bring cloudiness in on Sunday with some snow possible Sunday night.
The low from the south may or may not become better organized Sunday night. Right now just an inch or two of snow is possible by Monday morning. We will need to watch this situation because this could turn into a more significant snow producer. There is also uncertainty about snow later Monday into Tuesday!
Sat 3/15: Becoming mostly sunny and milder. Windy! High 57.
Sun 3/16: Some sun early, then becoming cloudy. Cold. High 44. A chance of light snow during the evening.
posted: Mar 14 2014 at 7:22 pm
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Sun, 02 Mar 2014Philly Winter Weather Update - Sun 10:30 PM
The latest GFS model data just available continues the trend showing the greatest precipitation to occur south of PA, into DE and MD. The cold air will suppress the major frontal moisture convergence south of PHL.
It currently appears that PHL will get around 4 inches. Areas just north, in Montgomery and Bucks counties will get 2 inches or less.
posted: Mar 02 2014 at 10:43 pm
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Philly Winter Weather Update - Sun 9PM
The latest NAM model data just available continues the trend showing the greatest precipitation to occur south of PA, into DE and MD. The cold air will suppress the frontal moisture convergence to our south
As I've mentioned for days, this particular scenario is very hard to predict accurately in advance, and it doesn't surprise me that this "major" storm for Philadelphia will become a fizzled storm for the immediate PHL area. (For Wilmington and Baltimore and Cape May, a still a significant storm.)
It currently appears that the immediate city will get around 4 inches, with even less in the northern suburbs.
posted: Mar 02 2014 at 9:10 pm
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Philly Winter Weather Update - Sun 12PM
This morning's models are out and the NAM remains emphatic about keeping the heavy precipitation to our south, near Baltimore. The GFS has also cut back on the expected snow totals as well. 4-7 inches is most likely at this point, with emphasis on the lower range. Totals will be lower as one goes further north of PHL.
The position of the stalled front and area of maximum convergence may still change and some uncertainty about snowfall amounts remains. Stay tuned.
posted: Mar 02 2014 at 12:16 pm
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Sat, 01 Mar 2014Philly Winter Weather Update - Sat PM
This afternoon's model runs underline the changeability and uncertainty of this type of stalled-front convergence precipitation event.
The models are now suggesting that the stalled front and the convergence zone will be further to our south. As a result, the amount of snow for Philadelphia looks to be much less than previously predicted. Currently, 4-6 inches looks like a better bet, with less further north.
Things may continue to change and uncertainty about snowfall amounts will continue. Stay tuned.
posted: Mar 01 2014 at 6:15 pm
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Philly Winter Weather Update - Sat AM
The models continue to predict a heavy snowfall for the Philadelphia area from late Sunday night through early afternoon Monday. Heaviest snow to fall during the morning hours of Monday. Still differences in the models with exact placement of the heaviest snow, but last night's GFS has the precipitation bullseye right over Philadelphia. Depending on the model, 6-8 inches of snow or 10-12 inches is what is currently expected.
As mentioned yesterday, this system is very different than past storms and uncertainties remain. Much of this storm's structure is really the result of a slowing frontal boundary being over-run by moisture, vs a compact low pressure system moving near us. This sort of scenario can result in forecast errors, since exact placement of the frontal boundary is difficult to forecast in advance with high precision. The predicted area of maximum convergence of cold and moisture may change. Stay tuned.
posted: Mar 01 2014 at 7:55 am
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Disclaimer: I am not a meteorologist and provide this information as a hobby and for entertainment (mostly my own :-) . While attempts are made to predict the weather as best as I can, use at your own risk! I am NOT responsible for any direct or indirect consequential injury/damages due to your use of these forecasts. Always check the NWS Official Forecast for your final plans.
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