Area Forecast Discussion
Issued by NWS Huntsville, AL

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872
FXUS64 KHUN 281218
AFDHUN

Area Forecast Discussion
National Weather Service Huntsville AL
618 AM CST Tue Feb 28 2017

.UPDATE...
For 12Z TAFS.

&&

.NEAR TERM...(Today)
Issued at 411 AM CST Tue Feb 28 2017

Moisture continues to stream into the cntrl TN Valley from the s this
early Tue morning, as low/mid clouds move into the region from the
w. Area radars are beginning to show a little bit of an increase in
development across wrn TN/nrn MS, as weak upper disturbances embedded
within a wnw flow regime begin to traverse over the area. The warm
front is still well s of the local area across the wrn/cntrl Gulf
Coast areas, although this boundary will be lifting nwd up the Lower
MS Valley later this morning, with convective activity increasing
along the front. Additional upper disturbances are also xpcted to
move across the area into the late morning/early afternoon hrs, with
showers/tstms increasing in coverage thru midday. Even with fairly
modest buoyancy/instability in place, low level shear profiles are
fairly impressive later today, with some of the short term models
suggesting 0-6KM shear values around 50-60KT. This may at least pose
a risk for a few strong to marginally svr tstms capable of strong
gusty winds later this morning into the early afternoon period,
mainly for areas along and w of the I-65 corridor. Outside of the
clouds and rain, unseasonably warm conditions are xpcted, with temps
climbing near 70F.

.SHORT TERM...(Tonight through Thursday)
Issued at 411 AM CST Tue Feb 28 2017

The short range guidance differs a little on the amount of convective
activity tonight, as the warm front continues to lift newd across the
area. In any case, will have sct showers/tstms in the forecast later
tonight ahead of an oncoming cold front from the w. As the cold front
approaches the MS River Wed morning, a squall line is xpcted to form
ahead of the sfc boundary and push ewd toward NW AL by the late
morning hrs. Instability and shear profiles remain supportive of
strong to severe tstms within this squall line, mainly around bowing
segments capable of producing damaging straight line winds. A low
tornado threat exists as well, mainly with individual storm cells
ahead of the main squall line. The line of storms looks to then exit
NE AL late Wed afternoon, with rainfall quickly tapering off from the
w early Wed evening.

Relatively quiet wx is then xpcted Wed night into Thu, as a strong
dome of high pressure out of the mid/srn Plains states builds ewd
into much of the SE states. The sfc high should also provide a little
bit of a cool down, as temps fall back into the mid/upper 30s Wed
night and then trend more seasonal like on Thu, as highs on climb
into the mid/upper 50s under clearing skies.

.LONG TERM...(Thursday night through Monday)
Issued at 411 AM CST Tue Feb 28 2017

A modified Canadian surface high sprawled across the Plains should
be building eastward at the beginning of the extended period. This
high will bring somewhat cooler than normal conditions to the
Tennessee Valley for the latter half of the week. Under generally
clear skies, highs on Friday will only warm into the low/mid 50s,
with night time lows in the low/mid 30s (a bit cooler Friday night).
But as the high shifts east of the area, temperatures should recover
to seasonable levels on Saturday - to around 60 (normal highs on Sat
Mar 4th are 61).

The surface high should be moving off of the coastal Carolinas on
Sunday, firmly placing this forecast area in a southerly flow, with
even warmer temperatures expected. Highs on Sunday should rise into
the mid 60s, and Monday, Mar 6th into the upper 60s. With the warmth,
a persistent lower level flow will bring more moisture from the Gulf
of Mexico inland to this region. This moisture and general lift will
bring chances of showers Sunday night. Daytime heating (highs in the
lower 60s) and resulting greater instability should be enough for a
few thunderstorms as well. Way too far out to speculate on storm
strength this far out, but from forecast soundings and convective
parameters, convection then should be mainly "general" in intensity.

&&

.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 618 AM CST Tue Feb 28 2017

Shra/tsra are beginning to spread newd into NW AL this early Wed
morning. This trend will continue into the late morning period across
the remainder of the area, as a series of upper disturbances move
over the region. Low cigs in the 1-2K ft range may lower just under
1K ft early this morning prior to any precip. MVFR cigs/conds are
then generally xpcted for most of the TAF period. Brief/tempo
reductions in cigs/vis will also continue in/near heavier shra/tsra
thru this afternoon and again late tonight. AMD NOT SKED has also
been added to the KMSL TAF due to comms issues.

&&

.HUN WATCHES/WARNINGS/ADVISORIES...
AL...NONE.
TN...NONE.
&&

$$

NEAR TERM...09
SHORT TERM...09
LONG TERM...RSB
AVIATION...09


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at weather.gov/huntsville.



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