Area Forecast Discussion
Issued by NWS Greer, SC

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632
FXUS62 KGSP 251112
AFDGSP

Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
712 AM EDT Wed Apr 25 2018

.SYNOPSIS...
A slowly moving low pressure system exits our region in mid week
and gives our region brief drying.  Another moist area of low
pressure crosses the region Thursday through early Friday. High
pressure builds across our area from this weekend into early next
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 700 AM: The last area of showers in the weak deformation zone
on the back side of the departing low will impact the northwest
piedmont through 10 am or so. Any lingering hydro issues should be
along the Rocky River in Cabarrus County, the Catawba chain, and
Blantyre along the French Broad this morning. Otherwise, anticipate
stages and pool levels to fall slowly through the day.

Water vapor imagery shows the closed upper low moving just east of
the central and southern Appalachians this morning, while the latest
surface analysis has the low center moving away across the NC
piedmont. Northwest winds will gradually pick up behind the
departing low. Some shower coverage may persist along the I-40
corridor in the moist northerly flow behind the surface low today,
but rates will be much less than previously. Anticipate that moist
northwest flow may also keep upslope showers going along the TN line
through the day. Shallow ridging will develop over the region today
as heights fall strongly across the southern plains. This upstream
system will deepen over the MS River Valley tonight. Persistent near-
surface moisture will permit some fog and low clouds to form both
this morning and again tonight around the region. Max temps will be
a touch below climo today, with mins about a category above climo
tonight.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 355 AM Wednesday: Aside from lingering precip along the TN
border, the break from unsettled weather across much of the area at
the end of the near term is expected to quickly come to an end as
precipitation will re-enter the western portions of the FA at the
beginning of the short term ahead of the next approaching system.
Latest guidance continues to be in fairly good agreement with the
placement of a 500 mb closed low within split flow over the MS
Valley Thursday morning, as it`s progged to weaken and become an
open wave as it moves into the Carolinas Thursday night. As a sfc
low pressure system moves up through GA and into the Carolinas on
Thursday, it`s accompanying warm front will lift north into the
Carolinas, potentially bringing part of the warm sector into the FA
before the associated cold front pushes eastward (remaining south of
the area), and the sfc low moves across the eastern Carolinas
Thursday night. With moisture return, expect showers to expand
across the area on Thursday with a few isolated thunderstorms
possible as limited instability becomes available across portions of
the Upstate and NW Piedmont. As the system moves off to the
northeast, another upper wave is progged to dive through the central
plains into the deep South behind it on Friday, sweeping offshore by
early Saturday morning with the upper longwave trough. Thus, do
expect precip will begin to taper off across the area into Friday
evening (possibly sooner). Temperatures will remain below normal,
with a slight warming trend on Friday.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 330 AM Wednesday: After an overall unsettled week across the
FA, the medium range forecast period which begins Saturday morning
is expected to be a quiet one. Latest guidance continues to
highlight an upper longwave trough progged to gradually push
eastward across the Northeast through the weekend, driving a dry,
weak cold front southward through the FA late Saturday into Sunday.
Given lack of available moisture, expect this front will not bring
any precipitation to the area, and even more, little to no change in
high temperatures on either side of the boundary. Behind this
feature, upper ridge will push east across the central US as sfc
high pressure builds in from the Upper Midwest. Through into early
next week, sfc high pressure will gradually shift over the Carolinas
and partially shift offshore. Temperatures will remain just below
normal through Monday, nearing normal on Tuesday.

&&

.AVIATION /11Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and Elsewhere: Any lingering showers should impact mainly
KHKY for a couple of hours this morning, with the departing band
generally northeast of KCLT. IFR to LIFR ceilings, with IFR to MVFR
vsby could still develop in a few places through 14Z given the
abundant near-surface moisture and some drying aloft. The conditions
may be quite variable, however, with a light downsloping NW flow at
times. Anticipate recovery to VFR throughout from 13Z to 15Z today.
Winds should remain generally N of W and become gusty at times at
KAVL.

Outlook: Moisture will return quickly to the region on Thursday
ahead of a vigorous southern tier low pressure system. Rain showers
and associated restrictions are likely into Thursday night. A drier
cold front will approach from the northwest early in the weekend.

Confidence Table...

            11-17Z        17-23Z        23-05Z        05-06Z
KCLT       Med   69%     High 100%     High 100%     High 100%
KGSP       Med   62%     High 100%     High 100%     High 100%
KAVL       Med   75%     High  94%     High 100%     Med   71%
KHKY       High  94%     High 100%     High 100%     High 100%
KGMU       Low   56%     High 100%     High 100%     High 100%
KAND       High 100%     High 100%     High 100%     High 100%

The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:

www.weather.gov/gsp/aviation

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.

&&

$$
SYNOPSIS...DEO
NEAR TERM...HG
SHORT TERM...SGL
LONG TERM...SGL
AVIATION...HG



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