Area Forecast Discussion
Issued by NWS Charleston, WV

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FXUS61 KRLX 271020
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
620 AM EDT TUE SEP 27 2016

.SYNOPSIS...
Weak high pressure crosses today. A large upper level low drops
into the area Wednesday and Wednesday night, and then swirls about
the area Thursday through Saturday, before pulling away Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 430 AM Tuesday...

Bulk of near term period should be dry. Cold front to the east of
the CWA...with drier air...dew points in the lower to mid
50s...filtering into the region. Gradual clearing occurring behind
the front...with low cigs lingering across the higher terrain in the
nwly flow...should scatter out by late morning. Otherwise...mostly
sunny...and cooler today...with some breezy conditions
developing...particularly across southeast Ohio...as an upper low
across the Great Lakes region gradually drops south into the
midwest...and as mixing of stronger winds aloft occurs during peak
heating hours.

Could see some patchy fog late tonight...mainly in deeper sheltered
mountain river valleys...with the cooler air over warmer waters.

Upper low will continue to dig south into the midwest late tonight
and on Wednesday...with the possibility of a slight chance for
showers developing just to our west towards Wednesday morning. For
now...left the near term period dry.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
As of 430 AM Tuesday...

The weather this period will be governed by a large upper level
low, which begins the period, 12Z Wednesday, near Chicago, and
ends the period, 12Z Saturday, in nearly the same area, maybe
closer to Toledo or Indianapolis. The system is progged to dig
southeastward into eastern Kentucky Wednesday and Wednesday night,
and then rotate through the forecast area Thursday and Thursday
night, before retreating northwestward, back through Ohio, Friday
and Friday night. The closed low cuts off from the main westerlies
as it digs southeastward early in the period and prior, and then
basically meanders beneath a rex block thereafter. After
depicting more progressive solutions, models have increasingly
converged on this solution over the past several runs.

The system drives a cold front through the area Wednesday into
Wednesday night, as it digs southeastward toward the area, and
then surface low pressure whirls about the area thereafter.

After a dry start, a line of showers and thunderstorms is likely
to cross the middle Ohio Valley ahead of the approaching cold
front on Wednesday, before lifting northward late Wednesday
beneath the upper level south to southwest flow. Some of the
showers should be able to push into the central Appalachians late
Wednesday into Wednesday night.

Additional embedded upper level short wave troughs rotating around
the upper level low late Wednesday night through Friday night will
be increasingly tough to time with increasing forecast projection,
but diurnal heating below the low upper level heights and
temperatures will result in greater coverage of showers during the
afternoon and early evening hours, when thunderstorms will also
be possible. Not coded, small hail may not be out of the question
given freezing levels dropping to 7-8 kft.

For now, it appears the system, whirling about the Ohio Valley,
will be far enough east so that an anomalous inflow of moisture
ahead of it will set up east of the forecast area, and so will the
more persistent, heavy, and potentially excessive, rainfall.

Lowered highs into the middle Ohio valley Wednesday given the
timing of the cold front, and associated showers and
thunderstorms. Once the cold front is through, temperatures will
be below normal, especially on highs, with small temperature
ranges given lots of cloudiness spiraling about the upper level
low. Only minor changes were needed in light of the latest
guidance, leaning toward bias corrected guidance at night.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
As of 320 PM Monday...

Operational and ensemble guidance is in pretty good agreement with
large upper level low remaining overhead well into the weekend.
With the cool temperatures aloft...any daytime heating we receive
will quickly yield showers and possible isolated thunderstorms.
The good news is that this should bring some much needed rainfall
to the region and amounts will remain light enough so we are not
expecting any hydro issues. The upper low meanders northward
Sunday into Monday with ridging moving in behind it. This will
bring warm air back into the region with upper 70s to near 80
degrees for the start of the next work week.

&&

.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
As of 620 AM Tuesday...

Some patchy LIFR/VLIFR fog has developed...particularly in
favored river valleys. This will generally burn off by 14Z.
MVFR/IFR cigs continue to linger across the higher
terrain...affecting sites such as KBKW. This will generally
scatter out to a VFR deck around 14-16Z. West-southwesterly winds
today. Some gusts in the teens are possible during peak heating
hours...dying off around sunset.

IFR fog is possible again tonight...particularly at TAF sites
adjacent to rivers.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z WEDNESDAY...

FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: Development and extent of any fog overnight
may vary from forecast.

EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH:   TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW:    TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.

UTC 1HRLY       10   11   12   13   14   15   16   17   18   19   20   21
EDT 1HRLY       06   07   08   09   10   11   12   13   14   15   16   17
CRW CONSISTENCY  L    L    L    L    H    H    H    H    H    H    H    H
HTS CONSISTENCY  L    L    L    M    H    H    H    H    H    H    H    H
BKW CONSISTENCY  L    L    L    L    H    H    H    H    H    H    H    H
EKN CONSISTENCY  L    L    L    L    L    H    H    H    H    H    H    H
PKB CONSISTENCY  M    M    L    M    M    H    H    H    H    H    H    H
CKB CONSISTENCY  L    L    L    L    H    H    H    H    H    H    H    H

AFTER 12Z WEDNESDAY...
Morning valley fog possible through Friday morning.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...None.
OH...None.
KY...None.
VA...None.

&&

$$
SYNOPSIS...TRM/SL
NEAR TERM...SL
SHORT TERM...TRM
LONG TERM...MPK
AVIATION...SL



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