Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 270916

Area Forecast Discussion
National Weather Service Columbia SC
516 AM EDT Tue Jul 27 2021

Showers and thunderstorms again Tuesday, with heavy rainfall
being possible where slow moving storms develop. Wednesday
should have showers and storms, especially across the south.
Expect drier weather on Thursday and Friday, with a more typical
summertime pattern returning over the weekend.


Low pressure to our south continues to slowly move northward
increasing onshore moisture flow. The frontal boundary to our
north is initiating some convection in North Carolina and will
continue to provide lift and moisture through the near term. The
atmosphere will become highly saturated this afternoon with
PWATs up to 2.3 inches. A shortwave will move from the north
this afternoon with widespread showers and thunderstorms. Sfc
based CAPE will be around 2500 j/kg in early afternoon along
with moderate lift. While there is some discrepancy of where
the greatest moisture will be from model to model, based on
current observations greatest chances of seeing some intense
rain producing cells will be along the coastal plain and CSRA
especially as the broad area of tropical moisture moves north.
Some heavier downpours may cause localized flooding.
Temperatures will be similar to those yesterday with highs in
the low 90s.

Tonight, energy and lift will decrease from west to east with
convection becoming more isolated after midnight. Some showers
possible as another shortwave pushes through the area but not as
widespread as those in the afternoon. The front will begin its slow
movement south overnight with decreasing cloud coverage. Dry air
will move into the upper and mid levels further decreasing rain
chances especially in the northern Midlands and along the Upstate.
Lows in the low to mid 70s with calm winds and patchy fog south of I-


Wednesday and Wednesday night...The weak cold front will continue
sliding southward through the Midlands and CSRA on Wednesday and
south of the area Wednesday night. Surface winds will turn
northwesterly by midday with low level flow turning northerly and
ushering drier air into the region. Although the boundary will be
moving southward expect slight chances of convection along and north
of I-20 with chance pops south of I-20. Instability will be moderate
and with the drier air filtering into the area dcape values will be
increasing. Potential for severe thunderstorms is low as best dcape
values will occur where drier air will be limiting development.
Along with that the northwesterly to northerly winds will allow for
some downsloping and drying along with pushing afternoon high
temperatures up a few degrees with most locations in the mid 90s and
slightly lower in the far eastern Midlands. Convection will quickly
diminish with sunset with some debris cloudiness lingering into the
overnight hours and low temperatures in the low to mid 70s.

Thursday and Thursday night...Remains of the front will continue
sliding south of the area with drier air remaining over the forecast
area and pwat values dropping to around 1.5 inches. Temperatures
will be the main focus on Thursday as afternoon highs will be in the
mid to upper 90s however with the northerly flow persisting heat
index values are expected to remain below 105. The drier
air...downsloping flow and front south of the area will make for a
dry forecast. With high pressure building west of the forecast area
Thursday night expect mostly clear skies however event with
excellent radiational cooling conditions overnight lows will
generally be in the mid 70s.


The period opens with a cold front draped along the VA/NC
border Friday morning. This boundary will sluggishly approach
the CWA through the day increasing cloudiness from north to
south. Recent guidance suggests that any showers and
thunderstorms will likely be confined to the northern half of
the forecast area and many locations could remain dry on Friday,
especially in the CSRA. It appears that this front will stall
over the midlands for the weekend bringing isolated to scattered
showers and thunderstorms, especially during the afternoon and
evening hours. A pattern change appears to be on the horizon to
kick off the new work week as a trough digs into the east
coast. If this manifests, it could result in several days of
scattered to widespread showers and thunderstorms across the
region starting on Monday.

In terms of temperatures, guidance continues to be bullish with
highs on Friday indicating values in the upper nineties. For
now, will continue the trend from previous forecasts of going a
few degrees below guidance putting the region in the mid-nineties
(93-97 degrees). Clouds associated with the previously mentioned
cold front will be on the increase limiting how hot some
locations will get. This has been reflected in the forecast
with the lowest temperatures across the northern half of the
CWA and the highest readings in the CSRA. Highs for the rest of
the long term will be near to slightly below normal due to the
likely development of afternoon and evening convection each day.


Low level moisture is expected to increase late tonight from
the coast as a tropical disturbance moves inland from the GA
coast. Fog and low ceilings will continue thru early morning.
Confidence in MVFR across the board but may see some IFR/LIFR at
OGB and AGS close to daybreak. Showers and thunderstorms
developing in the afternoon as the front sinks down and coastal
moisture moves in.

EXTENDED AVIATION OUTLOOK...Scattered to numerous showers and
thunderstorms expected through Wednesday as a frontal system
moves into the area.




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