Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 210224

Area Forecast Discussion
National Weather Service Columbia SC
1024 PM EDT Sat Jul 20 2019

An upper-level ridge will dominate through Sunday, reducing the
coverage of diurnal thunderstorms. An upper-level trough will
dig into the eastern US early next week with a cold front
entering the region midweek, resulting in widespread showers
and thunderstorms.


Weak surface troughing will continue with ridging just south of
the area. Moisture has become shallow with upper ridging more
dominate. Thunderstorms have been confined to the area west of
the forecast area closer to a weakness in the upper ridging. H7
temperatures were near 10 C locally. Expect mostly clear skies
tonight. The drying that has occurred should help prevent fog.
The GFS and NAM MOS, HRRR, SREF, and crossover temperatures were
in agreement with a diminished risk of fog. The guidance was
consistent with lows in the lower and middle 70s.


High pressure aloft will remain over the region through Monday.
Subsiding air and precipitable water values 1.5 to 1.75 of an
inch should limit thunderstorms to diurnal isolated coverage.
Abundant insolation should lead to high temperatures in the
upper 90s to around 100 degrees.

An unseasonably strong upper-level trough will move into the
Eastern U.S. midweek with a cold front pushing into the forecast
area Tuesday. Precipitable water values increase to more than 2
inches. The combination of increased moisture and forcing
should lead to showers and thunderstorms with heavy rainfall.


We have low confidence in timing the passage of a cold front through
the Midlands and CSRA through Thursday. Pushing a front
completely through the region is unusual in late July. Will keep
slight chance or low chance POPs in the forecast given the low
confidence. The front becomes diffuse toward the end of next
week which transitions the weather back to a typical summer
pattern. Temperatures will be below normal during this time
period due to midweek clouds/rainfall and a modified Canadian
air mass.


VFR conditions expected through the TAF period.

Skies have mostly cleared, but there are some scattered mid-
level clouds moving in from the west. Winds will either be out
of the SW or becoming light and variable. Drier air will move
over the area overnight, and at this time the remaining moisture
appears too shallow for widespread fog or stratus to develop.
Scattered fair weather cumulus expected again on Sunday, but
shower activity should be minimal. Southwest winds will also
once again increase to 5 to 10 kts.

EXTENDED AVIATION OUTLOOK...A frontal system will move into the
area on Tuesday with increasing moisture and likely restrictions.




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