Area Forecast Discussion
Issued by NWS Columbia, SC
FXUS62 KCAE 251529 AAA
Area Forecast Discussion...UPDATED
National Weather Service Columbia SC
1129 AM EDT SAT JUN 25 2016
A weak cold front stalling near the forecast area today will
dissipate by Monday. Another cold front will move into the area
Tuesday and become stationary. The pattern supports scattered
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Morning analysis revealed a pocket of drier air across south
central NC and north central SC with mesoanalysis data showing
precipitable water values under 1 inch and lower moisture at
925mb/850mb. This was consistent with blended total precipitable
water satellite product and LAPS/RAP soundings. The NAM/GFS 6hr
forecasts at 12z showed much higher values of precipitable water
closer to 1.5 inches so they both seem to be underplaying the
drier air. Surface winds have shifted to the north and northeast
across much of the northern and western parts of the Midlands and
CSRA with lower dewpoints in the 60s generally west of the I-77
corridor into the Piedmont region while dewpoints remain in the
70s across the central and eastern Midlands. A southward slowly
moving surface front was noted on visible imagery from near Myrtle
Beach westward to Camden late this morning.
The front is expected to continue to slowly sink southward as the
atmosphere becomes moderately unstable and should provide a focus
for convective development this afternoon. Latest hi-res
convective allowing models indicate scattered storms this
afternoon and focused along the Pee Dee region and eastern
Midlands. Decided to remove pops from the northwestern Midlands
due to the drier air in place but will continue the slight chance
pops for the remainder of the area and low chance pops along the
far eastern Midlands and CSRA due to better moisture and in the
vicinity of the surface boundary. SPC has the area outlooked in a
marginal risk for severe weather and cannot rule out an isolated
strong to severe storm with a damaging wind threat this afternoon.
Surface heating will be strong again despite the shallow front
pushing through the area as temps range from around 100 in the
CSRA to the lower 90s in the northern Midlands where thicknesses
are lowering behind the front.
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
The models display a surface ridge extending from off the Mid
Atlantic coast southwestward into the forecast area Sunday. The
models depict a diffuse front near the south part of the area.
Upper ridging extending into the area from the west should help
keep moisture shallow. Weak convergence associated with the
front and possible sea breeze boundary plus heating supports a
small pop mainly in the south part of the forecast area. Leaned
toward the higher temperature guidance because of recent
verification and upper ridging.
.LONG TERM /MONDAY THROUGH FRIDAY/...
The GFS and ECMWF have upper ridging extending into the forecast
area early in the period with the ridging shifting farther
westward by the middle of the week. The models show deeper
moisture ahead of a cold front Tuesday supporting an increased
chance of thunderstorms. Deep moisture may continue during the
rest of the period with the front stalled near the area and an
amplifying upper trough. The GFS and ECMWF MOS have pops 20
percent or less Monday, and 30 to 50 percent during the rest of
the period. The MOS supports temperatures near climatology.
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions expected at the terminals through this evening then
MVFR and possible IFR cigs expected to develop.
Surface front pushing south through the region today with
generally northeasterly winds 6 to 10 knots and isolated to
scattered convection this afternoon. Low coverage and uncertainty
lead to low confidence a terminal will be directly affected so not
included in the forecast at this time. Favored area for storms
appears closer to the coastal plain and north of the terminals.
Low level moisture increases overnight behind the front and
stratus clouds expected to develop and impact CAE/CUB/OGB after
08z and possibly AGS/DNL around 12z.
EXTENDED AVIATION OUTLOOK...Diurnal convection expected through
Monday. The chance for convection will increase Tuesday as a cold
front crosses the region.