SAMPLE WEATHERCASTS

Sunday, February 27, 2011

Severe Thunderstorms Possible Monday

Summary:
A line of thunderstorms will race across the area from 3 PM to 10 PM on Monday. The strongest storms will be capable of damaging straight line winds and small hail.

Discussion:
Temperatures will soar into the upper 70s to near 80 on Monday. This heat will provide *just* enough fuel for thunderstorms later in the afternoon and evening.


Storms will initially start west of the Blue Ridge around midday. They should form into a squall line and then race our way. The leading edge of the storms will be moving into western parts of our area around 3 PM.


The atmosphere will only be marginally unstable once the storms arrive, so we could see some weakening of the squall. Nonetheless, any storms that survive the trek across the Blue Ridge will be capable of damaging wind gusts over 70 mph. There could also be some small hail with the strongest storms. Most of the rain will quickly taper after midnight.




Limiting Factors (technical):
Just like last time, we will have a highly sheared environment with only marginal instability. However, upper-level "lift" could overcome this obstacle.

CAPE, or energy in the atmosphere, will be somewhat limited. Here is a plot for tomorrow evening, which shows almost 1000 CAPE west of I-95 (not too impressive). In addition, CAPE is much less in central VA. This could lead to some weakening of storms, especially after sunset. The key will be sunshine...if we see more, then the air could become more unstable.

Shear is going to be very high. The upper level winds will be howling! This will add to the potential of some powerful downbursts. It could also help to maintain the strength of the squall line. On the flip side, it could also rip apart storms as they try to develop. This is something to watch closely tomorrow - shear vs instability.

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