Area Forecast Discussion
Issued by NWS Columbia, SC
FXUS62 KCAE 261437 AAA
Area Forecast Discussion...UPDATED
National Weather Service Columbia SC
1037 AM EDT FRI AUG 26 2016
Upper-level high pressure will remain over the region through early
next week, then begin to weaken mid to late next week. This will
maintain generally fair conditions through early week, though a
slight chance of afternoon showers or an isolated thunderstorm
will be possible. As the upper ridge weakens next week, an area
of low pressure, possibly tropical, could influence our weather.
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Water vapor imagery this morning indicated center of the upper
ridge over southwest Virginia with a westward moving shortwave
over northern Florida and another over the western Atlantic
rotating around the periphery of the upper high pressure system.
Surface analysis indicated weak high pressure over the region with
a cold front extending from a low over eastern Canada through the
Ohio Valley back into the Central Plains states. Mesoanalysis
showed a band of enhanced precipitable water values across the
northern half of the forecast area with peak values around 1.75
Reasonably good consensus among the operational global model and
hi-res model guidance showing a surface trough developing near the
northern and western Midlands, providing a focus for diurnal
convection. Weak to moderate instability is forecast with strong
surface insolation but some factors inhibiting convection will be
warm mid level temperatures resulting in poor mid level lapse
rates and general subsidence beneath the upper ridge. Decided to
reintroduce slight chance pops across the northern and western
Midlands during the 17z-23z time frame but think severe
thunderstorm potential is quite low and thunderstorms in general
may be limited.
Temperatures have rapidly warmed this morning with Columbia
already at 88 degrees before 11 am and expect temperatures in the
mid 90s again today.
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
Upper level high pressure will remain over the region on Saturday
while surface high pressure ridges into the area from the
northeast promoting onshore flow. The highest atmospheric moisture
appears to be in the northern portion of the area, so continued to
indicate slight chance pops north. Convection should diminish
Saturday evening with the loss of daytime heating. The upper
ridge will promote above normal temperatures with highs in the
middle 90s. Overnight lows in the lower 70s.
.LONG TERM /SUNDAY THROUGH THURSDAY/...
Upper level high pressure will remain over the region on Sunday
before weakening on Monday. Onshore flow will continue with high
pressure ridging into the region from the northeast. Models
continue to disagree in regards to the disturbance producing
disorganized showers and thunderstorms near the Bahamas. Therefore,
confidence regarding if and how this disturbance could affect the
forecast next week is low. Temperatures will generally be near or
a couple of degrees above normal through the period.
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
Generally VFR conditions expected through the forecast period.
High pressure at the surface and aloft will persist through the
period with generally fair weather expected. An axis of higher
moisture was noted across the northern Midlands which along with a
surface lee trough that develops this afternoon, may support
isolated convection. Any convection that develops is expected to
remain north and west of the terminals and have little if any
impact so no mention of restrictions or rain in the forecast.
Winds expected to pick up from the east around midday and back to
the southeast by this evening at speeds less than 8 knots. Expect
some scattered cumulus clouds to develop with daytime heating.
EXTENDED AVIATION OUTLOOK...There may be widespread stratus and
fog associated with low-level moisture in an onshore flow during
the early morning hours over the weekend.