Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 290746

Area Forecast Discussion
National Weather Service Columbia SC
346 AM EDT Mon May 29 2017

Ridging over the region will weaken today as a frontal boundary
slowly pushes into the area. The front will stall over the area
Tuesday with chances of showers and thunderstorms each day
through the week.


Satellite imgaery shows generally clear skies across the
forecast area except for some passing cirrus. Further to the
southwest along the western and central Gulf Coast states,
convection is ongoing and looking at the regional radar loop,
it appears an MCV has developed over eastern Mississippi. This
feature may become a key factor in how the evolution of diurnal
convection impacts our area.

A closed upper low over the Great Lakes will continue to slowly
drop southeastward today with southwesterly 500mb flow over the
southeastern states. Abundant low level moisture already in
place with dewpoints in the upper 60s but the remainder of the
atmospheric column has dried a bit with precipitable water
values from the current LAPS around 0.90 inches. Forecast
soundings indicate instability will be weaker than on Sunday but
still sufficient to support an isolated severe thunderstorm risk
and SPC continues to outlook the area in a slight risk. Long
unidirectional hodographs favor a damaging wind threat as the
main hazard. Wind shear is not as strong as it was Sunday so
storms may be moving a bit slower and precipitable water values
are forecast to surge well over 1.5 inches after 21z with
relatively high freezing level and -20C levels supporting a
heavy rain threat.

The MCV moving through MS early this morning will lift
northeastward and be located just to the west of the forecast
area during peak heating this afternoon and likely will provide
enough lift to initiate convection which is expected to move
into the area late afternoon through the evening hours. Will
continue to carry low pops through early afternoon and then
increase them to high chance by 00z. Max temperatures today
will be in the lower 90s.


Tonight: With intersecting boundaries and instability into
tonight expect scattered convection into the overnight hours.
Latest model runs have some disagreement with timing and areal
coverage of convection, but overall will keep high chance pops
late this evening, diminishing slowly during the overnight
hours. Lows tonight will be mostly in the upper 60s to low 70s.

Tuesday will be similar...however with the front stalling over
the area expect the best chances for convection to be along and
south of the front. Instability Tuesday will be strong and with
dry air persisting in the mid and upper levels will again see
potential for damaging winds. Tuesday afternoon highs will be
in the middle to upper 80s with overnight lows mainly in the
middle to upper 60s.


Only a few changes to the extended forecast at this time. GFS
indicating that the old front will either slowly move out or
dissipate by Thursday, with another weak front moving into the
area by the weekend. This will keep chances of mainly diurnal
showers and thunderstorms in the forecast each day through
Sunday, with Thursday perhaps being the driest day. Concern with
convection for Thursday onward will be potential for heavy
rainfall as high pressure over the western Atlantic will result
in southerly flow and open the area to moisture from the Gulf of
Mexico. Temperatures through the long term will be near normal.


VFR conditions expected through the TAF period outside of
showers and thunderstorms Monday afternoon and evening.

Earlier convection has ended and only high cirrus clouds are
traversing the forecast area. Abundant low level moisture is in
place but a 25 knot low level jet should help keep the boundary
layer mixed and limit fog formation, although OGB already
showing lowering vsbys so will include a window of possible MVFR
vsbys from 08z-11z there.

A frontal boundary near the area will provide a chance of
showers and thunderstorms late Monday afternoon and evening.
Confidence in timing and exact location difficult so will
include only vicinity showers with this forecast generally after
21z. Winds will be light overnight and will pick up after
daybreak on Monday out of the west-southwest to around 5 to 10

EXTENDED AVIATION OUTLOOK...A cold front will stall over the
region through early next week. The front will help support
scattered thunderstorms and possible restrictions.




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