Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 221531

Area Forecast Discussion
National Weather Service Columbia SC
1131 AM EDT FRI JUL 22 2016

High pressure will be in control of the region through the
weekend with another weak frontal boundary returning to the area
early next week. With temperatures rising through the weekend
chances of mainly afternoon and evening showers and thunderstorms
will continue each day.


Weak frontal boundary has slide south of the area with some drier
mid level air trying to move into the area. WV satellite imagery
shows upper level cloudiness...mainly convective
debris...continues to move into the region as mid and upper level
flow remain northerly. Although instability will be moderate today
pwat values have lowered slightly and a significant trigger
mechanism is also lacking. As a result expect less thunderstorm
coverage this afternoon and evening compared to the last couple of
days. Expect thunderstorms which develop to be mainly over the
southern Midlands and CSRA where a bit higher moisture resides and
less mid level dry air intrusion. Temperatures this afternoon
remain on track for highs in the mid to upper 90s. Some convective
debris cloudiness will again be over the area tonight
which...along with a developing low level jet...will lower the
fog potential. Overnight lows will be in the lower to mid 70s.


On Saturday, the upper ridge builds into the region with
precipitable water values increasing back to near normal values
around 1.8 inches. A surface trough also expected to develop and
provide a possible focus for convection if it can get going
despite rising upper heights associated with the eastward building
upper ridge. Organized convection is not expected, but could see
locally heavy rainfall given weak steering flow. Temperatures will
continue to rise with highs expected to approach or reach triple
digits and heat indices around 105 degrees. Models remain
consistent with overnight lows in the 70s.


The upper ridge axis will persist across the Tennessee Valley into
the Carolinas on Sunday with temperatures remaining hot in the upper
90s and low 100s with heat indices nearing advisory criteria.
Isolated diurnal convection possible with moderate instability on
Sunday although subsidence from the upper ridge may limit convection.

The upper ridge axis will weaken and begin to retrograde westward
back over the central plains as an upper trough moves across the
Great Lakes region into New England early next week.  A surface
front will also approach the region stalling out north of the
forecast area Mon/Tue and then will push a bit further south
possibly into our northern counties by mid week Wed/Thu before
becoming diffuse.

The forecast area will remain in the warm sector during this period
with above normal atmospheric content as precipitable water values
are forecast to be close to 2 inches and even higher closer to the
frontal boundary which should support diurnal convection.  Tuesday
appears to be the day with the highest chances for convection with
some shortwave energy and the frontal boundary near the area with
the northern Midlands most favored.

Temperatures through the period will remain above normal throughout
with the warmest days occurring Sun/Mon.


VFR conditions expected through the TAF period.

High thin debris clouds remain over the region from upstream
thunderstorms with a few cumulus developing closer to the coast.
Expect cumulus to expand in coverage through the afternoon hours
with a few thunderstorms possible...mainly around OGB/AGS/DNL.
Potential for thunderstorm impacts at TAF sites currently remains
to low to include mention. Convective debris clouds will remain
over the area tonight and with a 25 kt low level jet developing
the fog potential also remains too low to mention.

EXTENDED AVIATION OUTLOOK...Low confidence in restrictions
in afternoon and evening convection each day. Low potential for
early morning fog/stratus each morning...mainly at AGS/OGB.




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