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Central PA & Fringes - Autumn dawns


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Any reports of hail in Harrisburg area. Looks like around strinestown in Northern York Co may have some on radar.

Nothing in downtown proper thankfully. Looks like the brunt of this wave missed us a hair to the SW. Waves of rain but no hail; lightning just crashed down across the river over near New Cumberland.

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Feeling like summer here with an overnight low of 66 and a dew point of 65 currently. After the initial band of showers moves through this morning, there may be another line of more convective showers later this afternoon. There's a bit of a cold front at 500 mb which could initiate new convection in a region of marginal surface-based instability. These storms will most likely not be severe with very weak environmental shear present.

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Cell that just passed over camp hill/capital city mall area no doubt had rotation... Thought the car was about to be flipped the way the wind and rain picked up...

Yea, it was pretty impressive when it ripped over work. See if I can get some decent shots off my phone today/tonight but there was a *LOT* of movement in the clouds and some very impressive lightning after the cell went through

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Could be an interesting day here in central and western PA as we get into the warm sector of the midwest surface cyclone, associated with a somewhat anomalously deep 500 mb trough.

 

As of this moment, there are some breaks in the stratocumulus allowing for some sun to break through the mid-level clouds. With the broad cyclonic flow, there has been some fairly humid air in place at the surface as well as at 850 mb. If we can destabilize enough, this air will mix down and, combined with surface layer moisture sources, increase surface dew points.

 

Interestingly, there is also some influence in the surface pressure field of the back door front that as pushed into northeast PA. This is backing surface winds to southeasterly. Getting above the influence of the marine layer, the 850 mb winds are more southwesterly, leading to significant (for central PA) low-level shear. Along with the stronger than normal flow at 500 mb, this will also provide decent deep layer shear over the area. The high amount of low-level shear and adequate deep layer shear should support the development of some supercellular features. However, given the limited amounts of CAPE, it may be hard for these storms to get organized updrafts initially with the low-level shear.

 

As a result, the SPC has put the southwestern diagonal of the state in a slight risk. As they mention in their discussion, storms should initiate near terrain-induced boundaries as sufficient daytime heating occurs.

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Also interesting to note, the 06z 4km NAM is showing the potential for significant flooding where some of these storms initiate along the direction of cell propagation. That training of storms along with PWAT values over 1.5" would certainly enhance the flash-flood risk.

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