Another Day, Another Chance of Pop Up Storms

We're waking up to some pretty thick fog in places this morning as residual moisture from last night's storms has helped to saturate the lower atmosphere and give us some rather low visibilities, with 1/4-1/2 mile visibilities common in many spots around the region.

Fog should lift later on this morning, leaving us under a mostly cloudy sky and providing the opportunity for some sunshine to filter through mid level overcast.  With the upper level low still in the picture, today will be similar to yesterday in that there is a chance for afternoon and evening pop up showers and storms.   Unlike yesterday, the storms shouldn't be quite as numerous and there will probably be a bit less overall coverage to today's activity compared to yesterday's as the mid atmosphere is a touch less moist.   However, the upper level feature and a surface trough provide enough agitation to the atmosphere to allow for precipitation to break out later on today, generally after 3 PM.

The NAM overlay up above shows the showers and storms popping up in the late afternoon hours, with the highest coverage across Central Pennsylvania and scattered elsewhere throughout the Mid Atlantic.   Any shower and storm that does pop up will probably taper off after sunset for a time...unfortunately to pick up in earnest late tonight as the upper low ingests tropical moisture off of the Atlantic on a southeast flow, bringing us a rather showery and thundery stretch of weather on Tuesday.  

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Foggy Start Gives Way To Northern Thunder Threat

A foggy...and showery in some spots...morning in the Delaware Valley as a frontal boundary lies about across the region.  It is a warm, summer-like morning that has many birds chirping up a storm at 5 AM as temperatures are in the 60's in many locations.   The frontal boundary lurks between the northern burbs and South Jersey, snaking across the Philadelphia area along where a few showers are falling this morning.   Those showers will exit over the next couple of hours and the fog will lift later on this morning, leading to a mix of sun and clouds and a humid April day as temperatures warm to around 80 or just above that in the city and across inland areas in the Delaware Valley, with 70's across the Lehigh Valley this afternoon.

The warming coincides with a northward advance of that frontal boundary, with said boundary acting as a trigger for thunderstorm activity in spots this afternoon and evening.   Best chances for storms will be dinner through 11 PM to the west and northwest of the city.   The Storm Prediction Center has much of Central Pennsylvania under a slight risk for severe weather, with that slight risk grazing the western suburbs.  Higher resolution radar below shows the thunderstorm potential this evening mainly west of Philly, with the NAM and  GFS in general agreement that the thunder threat stays out west.

The front will lift north and provide us one relatively thunder-free day in the coming warm stretch -- Tuesday looks to be the nicest overall day as temperatures get into the 80's again away from the coast.   We say "relatively" thunder free as there is still a chance for thunderstorms to our west in Central PA...odds favor Tuesday's storms staying west, which means warmth and more sun than none for us.

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