FXUS62 KCAE 190710
Area Forecast Discussion
National Weather Service Columbia SC
310 AM EDT Mon Mar 19 2018
.SYNOPSIS...A warm front will be south of the forecast area today.
The front will lift northward and into the area tonight ahead of
approaching low pressure. The low will be in the region Tuesday and
northeast of the area Wednesday.
.NEAR TERM /THROUGH TONIGHT/...
A low-level easterly flow will occur in the forecast area today
north of the warm front extending through central Georgia. The
models indicate weak isentropic lift. The moist low-level flow
and lift support showers. The models keep the isentropic lift
weak and also maintain flat upper ridging. This should limit
general rain amounts. The NAM, GFS, and ECMWF have amounts less
than one-quarter of an inch. Breaks in the cloudiness this
afternoon and relatively cold h5 temperatures near -15 C could
help support a few thunderstorms. Believe these would be mainly
elevated with the warm sector staying south of the forecast area
through the day as depicted by the NAM surface-based LI pattern.
The GFS showed more instability getting into the south part of
the forecast area adding uncertainty, but it also depicted the
more significant instability remaining south of the forecast
area through the day. Still, the instability and shear near the
warm front that could possibly get into the CSRA this afternoon
supports some possibility of severe thunderstorms. There will be
a strong north-south gradient in temperatures today. The gradient
makes the temperature forecast uncertain. We forecasted
temperatures a little below the guidance consensus because of
cloudiness. Expect highs in the upper 50s in the north to around
70 in the south.
There is a potential for more instability tonight with h5 cooling
associated with upper troughing and the warm front lifting northward
ahead of the approaching surface low. The models indicate increasing
shear with h85 wind increasing to 40 to 50 knots. The NAM and GFS
show surface-based LI values lowering to -2 to -5 overnight.
The greatest shear and instability is depicted in the southeast
section of the forecast area. The shear and instability support
possible severe thunderstorms with the added shear associated
with the warm front supporting a tornado threat as well. The
main limiting factor may be more significant convection south
and east of the forecast area which may limit the moisture and
instability locally. The SPC has outlooked a marginal to slight
risk of severe thunderstorms in the central and south section of
the forecast area.
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
Showers and thunderstorms may linger Tuesday with low pressure
in the area. The models display deeper moisture east and south
of the area so there may be limited coverage. There will be
further cooling aloft associated with upper troughing moving
into the area. The models show continued high shear mainly in
the east section. A few strong to severe thunderstorms will be
possible. Temperatures could warm significantly ahead of a cold
front approaching from the west. There is high spread in the
temperature guidance. We followed a consensus for the forecast.
The cold front should move through the area Tuesday night with a
continued shower chance. Behind the cold front there likely
will be considerable wrap-around moisture associated with low
pressure lifting northeast of the area. The shower chance
Wednesday will be greatest in the north section closer to deeper
moisture and colder air aloft.
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Dry ridging is forecast to dominate Thursday and Friday. The
GFS and ECMWF MOS have temperatures during the early morning
hours Thursday and Friday in the middle and upper 30s. It may be
cold enough for frost. The models show much of the moisture
associated with a warm front north of the forecast area Saturday
and little moisture along a cold front Sunday. The GFS and
ECMWF MOS have pops 20 to 30 percent.
.AVIATION /07Z MONDAY THROUGH FRIDAY/...
VFR conditions are persisting with mainly mid level cloudiness,
despite showers moving in. Some upper energy is interacting
with a stalled front to our south and west leading to isentropic
lift and associated precipitation. Expect periodic showers at
all terminals through Monday morning. Weak in situ wedge will
develop in response, leading to deteriorating CIGs by morning.
These lower CIGS will be slow to improve Monday, with some
diurnal rises in CIG heights possible during the afternoon.
Latest 4km NAM shows a round of thunderstorms moving through the
area after 20/00Z. Have indicated VCTS for now due to
EXTENDED AVIATION OUTLOOK...Chance of thunderstorms Monday
night, possibly severe. Flight restrictions and precipitation
chances possible at times Tue/Wed. Breezy conditions possible
Back to Main Forecast Discussion Page