Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 270229

Area Forecast Discussion
National Weather Service Columbia SC
1029 PM EDT FRI AUG 26 2016

Upper-level high pressure will remain centered over the Mid
Atlantic region through early next week, then weaken mid to late
next week. A weak surface trough will provide a slight chance of
showers or a possible thunderstorm Saturday afternoon, mainly
northern and eastern areas. An upper level disturbance will
provide a chance of showers or thunderstorms Sunday afternoon and
evening, mainly southern and eastern areas. As the upper ridge
weakens next week, an area of low pressure, possibly tropical, and
associated moisture, could influence our weather. However,
considerable uncertainties still exist with this system.


No change in the forecast for the overnight. Upper level ridge was
centered over the Mid Atlantic region with surface high pressure
ridging into the area from the northeast.

Convection has ended across the forecast area for the night with
mostly clear skies. Overnight lows expected to cool into the lower
70s as per guidance consensus.


Upper level high pressure will remain centered over the Mid
Atlantic. The surface trough appears will generally stall near the
N/NE FA Saturday. This, along with some low level onshore flow and
associated gradual moistening, provides a slight chance of showers
or isolated thunderstorms possible Saturday afternoon, mainly
northern FA near the trough, and possibly E/SE FA near a sea
breeze. On Sunday, an upper shortwave rotating clockwise around
the periphery of the upper high, will shift west into our region
late Sunday. Associated lift plus some additional low level
moistening will provide a chance of showers and thunderstorms,
mainly S/E FA.


Upper high still progged to weaken as energy on the southern
periphery of the ridge combined with digging trough in the
northern stream, to provide upper troughiness over the E CONUS.
Main forecast issue is status of tropical disturbance to our
south which could possibly organize into a tropical cyclone and
affect our region. A preponderance of the models suggests that the
system would drift towards the E GOMEX and FL and eventually take
a turn east in response to developing upper trough. Still
considerable uncertainty whether the system will even develop,
much less the eventual track. Nonetheless, moisture from the
system expected to drift north towards our region, and along with
upper high weakening, should provide premise for at least
scattered diurnal convection if nothing else. Accepted model blend
of mainly chance pops.


VFR conditions are expected to prevail through 00Z Sunday.

Skies are generally expected to remain clear through the
overnight hours with light to calm winds at all terminals. MOS
guidance continues to suggest MVFR visibilities developing due to
patchy fog at KAGS and KOGB during the predawn hours. However,
given a lack of any fog the past few mornings, no strong
indication of fog developing on any of the high-resolution
mesoscale models or the SREF, and cross-over temperatures which
will likely not be reached, have kept mention out of the forecast.
As for any convection, the greatest potential for isolated showers
and thunderstorms appears to remain north of the terminals during
the day Saturday in the vicinity of a surface trough.

EXTENDED AVIATION OUTLOOK...There may be stratus and fog
associated with low-level moisture in an onshore flow during the
early morning hours late in the weekend and early next week.




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