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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRLX 270732
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
332 AM EDT Thu Jul 27 2017

.SYNOPSIS...
Low pressure system brings rounds of showers and thunderstorms,
with heavy rain through Friday. High pressure with cooler and
less humid air follows for the weekend into next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 300 AM Thursday...

A cold front will slowly sink southeast across the Ohio River
valley through tonight. This will increase the threat of
showers and thunderstorms, particularly from afternoon on.
Meanwhile, the atmosphere will rapidly moisten with precipitable
water values quickly approaching 2 inches by this afternoon.
Currently, the HRRR has a decent handle on the convection moving
into Indiana. The trend will be weaker over the next several
hours transitioning to a broken line of showers as it approaches
the western part of the forecast area by mid-morning. From
there, diurnal heating should help this increase in coverage and
intensity as it pushes across West Virginia this afternoon.

From there, it will depend on the timing and placement of weak
waves of low pressure that develop and move along the frontal
boundary to assist in shower and thunderstorm development.

Overall, there doesn`t seem to be a whole lot of instability and
available energy. This may limit the high end potential of storm
strength and coverage. So, while I do expect most areas to see
showers and thunderstorms, I do not expect any specific location
to continually be impacted today. Better coverage may wait until
later tonight or Friday as the surface cold front approaches to
provide more widespread lift.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 315 PM Wednesday...

Models in general agreement with the overall progression of the
cold front pushing through the area with sfc pressure riding
up along it, then exits Saturday morning with the aid of a very
progressive upper level low rotating through. Main concern
where heaviest axis of rain sets up. Models still differ on
exact placement through the period and will hold off on any FFA
possibilities for now. Will still keep the mention of heavy
rain potential in the HWO for Friday.

A cool and dry high pressure system will build in behind the
front later Saturday and Saturday night.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 335 PM Wednesday...

A cool and dry period is on tap as cool Canadian high pressure
will be in control for much of the work week. There will be a
slow increase in high temperatures each day, but it will be dry
with temperatures at or below normal.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
As of 300 AM Thursday...

Fog early this morning should be limited to the valleys of
northeastern West Virginia, as a low pressure system approaching
from the west brings increasing clouds. Have IFR only in the
Tygart Valley and MVFR mist for CKB, PKB and possibly CRW /6SM
coded there/.

The likelihood for showers and thunderstorms increases as the
day progresses today. Clouds and the near widespread coverage
of the showers and thunderstorms limits the severe risk, but
thunderstorms could still produce strong wind gusts, and any
thunderstorm can bring IFR conditions in heavy downpours.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY...


FORECAST CONFIDENCE: Medium to high.

ALTERNATE SCENARIOS: Formation and timing and dissipation of
fog could vary early this morning. Timing of showers and
thunderstorms, and associated flight categories, could vary
later today and tonight, with short term amendments likely
needed.

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.

DATE                              THU 07/27/17
UTC 1HRLY       06   07   08   09   10   11   12   13   14   15   16   17
EDT 1HRLY       02   03   04   05   06   07   08   09   10   11   12   13
CRW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    M
HTS CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    M
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    M
EKN CONSISTENCY  M    M    L    L    L    L    M    M    H    H    H    M
PKB CONSISTENCY  M    M    M    M    M    L    M    H    H    H    H    M
CKB CONSISTENCY  H    H    H    M    M    H    H    H    H    H    H    M

AFTER 06Z FRIDAY...
Brief periods of IFR conditions with thunderstorms likely
tonight into Friday, perhaps more persistent in low clouds
Friday morning.

&&

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

&&

$$
SYNOPSIS...JS/99
NEAR TERM...99
SHORT TERM...JS
LONG TERM...JS
AVIATION...TRM/99