Scientific Forecaster Discussion
fxus62 kcae 190636
Area forecast discussion
National Weather Service Columbia SC
236 am EDT Tue Jun 19 2018
weak surface trough will remain across the region, however a
building upper level ridge aloft through midweek will limit
afternoon thunderstorms and result in warmer than normal
temperatures through most of the week. Increasing moisture late
in the week along with the ridge weakening may result in an
increase in scattered afternoon thunderstorms late in the week.
Near term /through tonight/...
strong upper ridge will be centered over the forecast area today
with a weak surface trough in the region. Atmospheric moisture
is somewhat limited with precipitable water values around 1.5 to
1.6 inches and forecast soundings indicate a subsidence capping
inversion. Warming temperatures in the mid levels along with the
capping inversion should limit convective coverage again today
and will only carry a slight chance across far northern midlands
and in the csra. However, any storm that develops will have the
potential to become severe due to strong instability with SBCAPE
values around 2500 j/kg and lifted index values around -7c.
Downdraft cape will be around 1000 j/kg as forecast soundings
indicate an inverted-v signature so damaging wind gusts would be
the main threat from any strong storms that are able to
Hot temperatures are expected today with highs in the upper 90s
to around the 100 degree mark. Heat indices will again top 100
degrees but will not approach our advisory criteria. Tonight
mostly clear skies are expected but after such a warm day,
temperatures will remain warm overnight with lows expected in
the mid to upper 70s.
Short term /Wednesday through Thursday night/...
the biggest concern in the short term forecast will be the heat. Near
record high temperatures are possible Wednesday and Thursday. Highs
will be close to 100 degrees with lows in the mid to upper 70s,
and heat advisories may be needed for heat index values near 110
degrees. An upper level ridge over the forecast area will bring
the hot temperatures. Model guidance has been consistently indicating
highs around 100 degrees. MOS has been close or slightly cooler than
verification over the past few days. Therefore continued to favor
the warmer temperature guidance since the models generally don't
recognize the added heating from compressional heating due to
westerly downslope flow.
Wednesday should start out dry, but with the high pressure
center shifting south, weak upper level energy may rotate over
the ridge. This combined with strong surface heating may allow
for a few widely scattered evening thunderstorms. Activity
across the northern midlands could also persist into the night,
as indicated by both the NAM and GFS.
Convection should stay west of the area during the day Thursday,
but could move in late evening in association with a back door
Long term /Friday through Monday/...
warm weather continues for much of the long term. Expect both high
and low temperatures to remain above normal.
A deep upper level trough will move through the center of the
country and approach the region on Friday. Southwest flow will cause
increasing warm, moist advection through the weekend as the
trough lifts to the northeast. This pattern supports an
increased chance of diurnal convection and above normal
temperatures through the remainder of the long term. There is a
good chance for showers and thunderstorms by Friday evening, and
again during the day Saturday. High pressure then tries to
build back in from the east on Sunday, so only kept a slight
chance. The primary cold front associated with the trough should
then finally push through by Monday night, bringing another
round of convection, and cooler temperatures for Tuesday.
Aviation /06z Tuesday through Saturday/...
VFR conditions expected through the 24 hr forecast period except
for possible patchy early morning fog.
Upper ridge is firmly in place over the region and mostly clear
skies expected overnight through the morning and then diurnal
cumulus clouds will develop with heating. Patchy early morning
fog will be possible mainly at fog prone ags, but BUFKIT
indicates a 20 knot low level jet which may be enough to
preclude development, so have not included any restrictions.
Light southwest winds will prevail through the period.
Extended aviation outlook...restrictions possible each day in
early morning fog and isolated afternoon and evening
near record high temperatures possible over the next few days.
Record highs (cae/ags year last set):
Tue: 104/103 1970/1933
Wed: 102/103 1924/1933
Thu: 106/104 1990/1990
Fri: 101/101 1988/2015
Record warm morning lows (cae/ags year last set):
Tue: 77/77 1939/1946
Wed: 77/78 1950/1881
Thu: 78/79 1924/1942
Fri: 77/77 1935/1939