Severe Weather Discussion for October 17 – 23, 2011

Severe Weather Discussion for October 17 – 23, 2011.
Issued:  10/16/2011.
Highlights:
–  One or two severe thunderstorms are possible tomorrow afternoon, primarily in far south-central and southeast Oklahoma.  Otherwise, thunderstorms are possible across the southeast quarter of the state.  Slight chance of showers on Sunday.
–  Temperatures will be in the low 80s Monday, mid 60s Tuesday, low 60s Wednesday, upper 60s Thursday, low 70s Friday, upper 70s Saturday and Sunday.
–  NHC is watching a system near the Yucatan, giving a 50% chance of development.
Probabilities:
–  Severe thunderstorms in Oklahoma:  5%
–  Storm Chase:  < 5%
–  Tropical Development:  10%
Discussion:
Models are in good agreement through the period on the general weather pattern.  A southern stream shortwave trof will move southeast across the state and help form a large eastern U.S. longwave trof.  Initial closed low over the eastern Canada will open and move east as the longwave trof matures and closes off by late Wednesday.  As the eastern Canada closed low spins, a decent chunk of cool air will head southeast into the region.  Frontal passage is expected Monday afternoon across the state.  Some low-level moisture, around 60F dewpoints, will move into the state.  Warm temperatures and a strong cap will battle each other for storm initiation.  Given the expected warm temperatures and CAPE values around 750 J/Kg, one or two severe thunderstorms cannot be ruled out.
Cold front will then move southward thru Texas by Tuesday afternoon, ushering in a cool day across Oklahoma.  A shortwave trof will dive southward on the backside of the long wave trof late Tuesday resulting in a reinforcing surge of cool air.  As such, Wednesday temperatures will likely be a little cooler than Tuesday.  After Wednesday, a warming trend will start, with temperatures finishing the forecast period above average over the weekend.  All POPs zero after frontal passage late Monday until Sunday.  GFS trof for Sunday may be a one run wonder, but can’t hurt to put in token POPs for Sunday.  If POPs do verify, temperature may be a little high.  All in all, a pleasant fall week looks like a good bet.
Went with NAM tomorrow on high temperature, although not quite as warm.  GFS appears too cool.  Beyond Monday, GFS numbers look find and didn’t make many changes.
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