Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Wilmington Ohio
410 PM EST Tuesday Nov 24 2015
high pressure will move east of the region tonight. Southerly flow
will bring a slow but continued increase in temperatures through
Friday...when a cold front crosses late in the day. High pressure
will build in the Great Lakes for the weekend...with the next low
pressure system taking aim on the Ohio Valley Sunday.
Near term /until 6 am Wednesday morning/...
another nice fall night in store for the region with clear to
partly cloudy skies and temperatures bottoming out near the
freezing mark. Still running just a tad on the warm side of
climatological lows tonight.
Short term /6 am Wednesday morning through Thursday night/...
very little change was made to the forecast. Dry weather and
southerly flow had ME err on the warm side of guidance and this is
more notable at night when viewed against surrounding offices. Sky
cover will increase northwest-southeast overnight Thursday...along with a
slightly marginal increase in the threat for showers that will
really begin to ramp up on Friday.
Long term /Friday through Tuesday/...
the extended looks to be rather wet as a cold front will stall
across the area with upper level energy moving in from the west.
This will help to keep rain chances in the forecast through most
of the extended. Friday morning an upper level low centered over
eastern Nevada will begin to detach from the main longwave trough
over south-central Canada.
Accompanying this longwave trough with be a surface cold front that
will move into the County Warning Area Friday evening. The longwave trough will
quickly pull east Saturday though allowing the surface cold front to
stall just south of the Ohio River. Rain chances will start to
quickly increase Friday as the cold front approaches from the
northwest. Precipitable waters Friday rise to near 1.3" (normal around 0.4" for
this time of year). Omega values are also lightning up near the
front which is not surprising given the weak positive vorticity advection and warm air advection. Jet
support remains a tad farther north than preferred but lift should
Saturday the front will stall just south of the area which will help
keep probability of precipitation in the forecast (esp. Southern parts of the cwa). Early
Sunday the stalled front will start to pull north allowing upglide
to commence. The upper level low on the West Coast that formed a Rex
block Saturday will finally start to get dislodged Sunday and
approach the area from the west. Sunday into Monday rain looks to
remain in the forecast as southwest flow aloft allows weak upper
level disturbances to traverse the area. It should be noted though
that on both the GFS and Euro a punch of dry middle level air does move
overhead sometime Sunday afternoon into Monday which could bring a
brief break to some showers but low level saturation remains stoutly
Rain chances again look to increase Tuesday morning as the upper
level low that was over the West Coast moves just north of the area
bringing another cold front through the area. Precipitable waters ahead of the
front look to be around 1.10". Tuesday afternoon the front will push
through the area bringing cooler conditions to the area.
Aviation /21z Tuesday through Sunday/...
surface high pressure will slide off into the Appalachians tonight. As
this occurs surface flow will become southeast. Models are indicting some
increase in 300 mb moisture. As is the typical issue with 300 mb
moisture...how much coverage will we get. Went with broken clouds
overnight...but wouldnt be surprised if it is thin or scattered.
With weak southeast flow kluk could see some fog. Confidence is low on
300 mb moisture decreases after 12z Wednesday...so took the cirrus to
scattered. Winds pick up in the southerly flow by afternoon...with gusts into
the teens expected.
Outlook...MVFR/IFR ceilings and visibilities possible Friday into Sunday.