Area Forecast Discussion
Issued by NWS Columbia, SC
FXUS62 KCAE 202333
Area Forecast Discussion
National Weather Service Columbia SC
733 PM EDT Mon Mar 20 2017
A frontal boundary will approach the area from the north on
Tuesday and slowly cross the area Tuesday night through
Wednesday with increased chances of showers and thunderstorms.
Very warm temperatures expected Tuesday followed by cooler
temperatures for the latter half of the week behind the front.
.NEAR TERM /THROUGH TUESDAY/...
Moisture will begin to increase as a cold front develops to the
north. Should see some increase in clouds through the night due
to upstream convection across Tennessee moving over the
Appalachians. Still do not expect any rain as moisture will
remain limited. Models do indicate that the convection west of
the mountains will hold together as it moves through the
mountains. The development of a low level jet will create
enough mixing to keep overnight lows near guidance
consensus...in the upper 40s and lower 50s.
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
A cold front will approach the forecast area from the Tennessee
Valley region on Tuesday and drop south across the area Tuesday
evening through early Wednesday. There will be adequate
moisture in place for shower and storm development late Tuesday
afternoon through early Wednesday with model precipitable water
values near 1.3 inches. Bufkit soundings show a mid-level cap,
but once the cap breaks, there is moderate instability with LI
values generally -3 to -7 and CAPE around 1000 J/kg late Tuesday
afternoon/evening. Models show shortwave energy moving through
the area during the 00Z to 06 Wednesday time frame, so have
indicated highest pops and QPF during this time. The front may
not make it to the southern FA until near daybreak Wednesday
morning when timing is less diurnally favorable for
thunderstorms. The most favorable location and timing for
thunderstorms appears to be in northern and central portions of
the area closer to the front and strongest shortwave energy
late Tuesday afternoon into early Wednesday. Severe weather is
possible with damaging winds and large hail as the primary
threats. Most of the area has been outlooked by the SPC in the
marginal risk category. The front will push south of the area on
Wednesday with a wedge of high pressure building in behind it.
Expect a sharp gradient in temperatures on Wednesday with highs
in the northern portion of the area in the middle 60s and middle
.LONG TERM /THURSDAY THROUGH MONDAY/...
An upper ridge over the Plains will promote northwesterly flow
aloft across the forecast area on Thursday while at the
surface, high pressure will be situated near the Mid-Atlantic
coast. Below normal highs on Thursday, in the middle to upper
50s. The upper ridge will build east over the forecast area on
Friday while surface high pressure pushes east into the
Atlantic. This will allow temperatures to rebound back into the
60s. A low pressure system over the southern Plains will lift
toward the southern Great Lakes region on Saturday with
unsettled weather returning to the area. This system will bring
a front into the forecast area on Sunday. Temperatures on
Saturday and Sunday will be above normal, in the 70s ahead of
.AVIATION /23Z MONDAY THROUGH SATURDAY/...
VFR expected through the TAF period. Surface high pressure over
the southeastern states will move south overnight as a cold
front north of the region slowly sinks southward. Winds will be
southwest 10 knots or less. Mid and high level clouds expected
to increase overnight. The development of a low level jet will
produce some mixing, so no fog is expected. Skies will partially
clear during the day Tuesday, but mid level clouds will increase
during the late afternoon. Showers and thunderstorms should
remain north of the TAF sites until after 22/00Z.
EXTENDED AVIATION OUTLOOK...Some shower and thunderstorm
activity, along with CIG VSBY restrictions possible Tuesday
night through Wednesday night as a frontal boundary moves
southward across the region.