768
FXUS61 KRLX 160541
AFDRLX

AREA FORECAST DISCUSSION
National Weather Service Charleston WV
141 AM EDT Mon Sep 16 2024

.SYNOPSIS...
Dry weather, and elevated fire danger, continues through Monday
under strong high pressure. An area of low pressure off the
Atlantic coast brings the next chance of rain mid-week.

&&

.NEAR TERM /THROUGH TODAY/...
As of 930 PM Sunday...

No major changes were needed this forecast period. High clouds
blowing off from Potential Tropical Cyclone Eight offshore the
Carolinas will continue to slowly work in over the CWA tonight
into tomorrow. A bit of valley fog possible in the more
protected mountain valleys, as synoptic flow may be a touch
lighter than last night, but the high clouds may then inhibit
formation. Still, the fog was left in for parts of the
Greenbrier, Tygart Valley, and Gauley Rivers.


As of 140 PM Sunday...

Hardly a cloud in the sky within the forecast area at the time
of writing as we remain under the helm of high pressure. Some
afternoon cumulus streaming along the east-southeast flow was
present down in the southern VA coalfields, but elsewhere
remains predominantly clear.

The main story for today remains the absence of low level
moisture alongside unseasonably warm temperatures. This
combination yields a concern for fire danger as daytime mixing
captures and brings down stout dry air parked above the mixing
level of around 5,000ft AGL. Resulting drops in RH values are
expected this afternoon and early this evening. Minimum relative
humidity values nearing the 20 to 30 percent range will be
present across the lower elevations this afternoon, in addition
to slightly breezier east-southeast winds along the higher
terrain. Both contributing to concern for the spread and
ignition of wildfires today, this warranted the Fire Danger
Statement across West Virginia that will remain messaged until
this evening.

Similar fire weather concerns will be present on Monday, but an
invasion of mid to upper level clouds from a disturbance off
the Carolina coast pushing inland will aid in lowering afternoon
highs. However, enough dry air intrusion still festering over
the area will yield minimum RH values in the 20-30 percent range
once again Monday afternoon, so will continue to highlight the
fire weather concerns in the HWO.

Aforementioned disturbance marching up from the Carolinas will
begin to introduce slight chances for precipitation within the
concluding hours of the near term period. POPs will first
increase across our southeastern zones and track north and
westward overnight Monday into Tuesday.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
As of 150 PM Sunday...

Key Point:

* Considerable model differences remain regarding low pressure
  off the Atlantic Coast yielding a low confidence forecast

Upper level ridging over the northeast gradually erodes/shifts
eastward Sunday night into Monday. This opens the door for a
area of (currently) non-tropical low pressure off the Carolinas
coast that could begin to take on some tropical characteristics
and potentially move inland starting as early as Monday.
Ensemble families are beginning to show some more consistent
clustering with solutions, inclusive of operational guidance,
this roughly falls into 2 camps:

1.) A northwesterly track as it approaches shore where central
low pressure moves into the TN Valley. This solution is most
common among GEFS ensemble members as well as the latest GFS
runs ending 06Z and latest NAM runs ending 12Z. This solution
would result a belt of relatively strong easterly low level flow
transporting tropical moisture into the region. While some rain
shadowing will take place with this belt of strong flow nearly
normal to our terrain, could see some pockets of decent rainfall
farther west, generally outside where the typical warm wedge
sets up, coincident with strong mass convergence where the wind
field begins to weaken. Non-mesoscale guidance with this
solution is likely too high with rainfall amounts in the rain
shadow if this solution were to verify, the 12Z mesoscale NAM
may be a reasonable answer for this solution though. The
headline here would be potentially beneficial rainfall for at
least portions of the D4 drought area north of the Kanawha
Valley. Heading toward the long term portion of the forecast,
this would also tend to have a longer loiter time of tropical
moisture over the region yielding continued unsettled weather
through the end of the week.

2.) A northerly track as it approaches land that moves up the
Atlantic Coastal plain. This solution is currently favored by a
majority of GEPS/EPS members, UKMET, operational Canadian/ECMWF
and a few GEFS members. It is also the basis for the WPC
forecast from the last cycle. This solution would minimize
barrier normal flow, but also limit westward expansion of the
tropical moisture plume with predominately north-northeasterly
flow across the region. This would confined a bulk of any 1+
inch rainfall totals to the mountains and adjacent foothills
with the highest totals across our northeast. Although there are
some members of this solution that would not eject the tropical
moisture out to the north, this would generally yield a quicker
return to dry conditions by the end of the week.

Overall, confidence in the forecast remains low with ranges in
interquartile 48hr QPF values in central guidance from
effectively no rainfall to near what the deterministic values
were in the last cycle. For now, will continue to largely defer
to central guidance for the deterministic forecast, if, for
nothing else, to at least maintain some consistency with our
neighbors. Highly confident that the deterministic forecast will
change substantially over the next 24 to 36 hours, also fairly
confident that some locations will see some beneficial rainfall,
with the highest confidence along and upwind of the highest
terrain.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 150 PM Sunday...

Uncertainty remains very high through the remainder of the
extended forecast owing to potential placement of residual
moisture from the low off the coast mentioned in the short term
discussion. In the absence of lingering tropical moisture,
expected sensible weather would be minimal as high pressure
builds back into the northeast.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
As of 130 AM Monday...

For this TAF period expecting VFR to dominate. Flow will be
easterly at around 5KT across the area with stronger flow along
the mountains particularly at BKW where gusts up to 20KT can be
expected during the day. That site will endure some llws this
evening temporarily until surface winds pick back up. Mainly
just high clouds today spreading across the sky which will
become likely overcast by this late afternoon.

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

FORECAST CONFIDENCE: High.

ALTERNATE SCENARIOS: None.

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                                             MON 09/16/24
UTC 1HRLY       03   04   05   06   07   08   09   10   11   12   13   14
EDT 1HRLY       23   00   01   02   03   04   05   06   07   08   09   10
CRW CONSISTENCY  H    H    H    H    H    H    H    H    L    H    H    H
HTS CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
EKN CONSISTENCY  H    H    H    H    H    L    M    M    M    L    H    H
PKB CONSISTENCY  H    H    H    H    H    H    H    M    L    L    H    H
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H

AFTER 06Z TUESDAY...
Widespread IFR conditions are not expected at this time.

&&

.FIRE WEATHER...
As of 150 PM Sunday...

Dry weather persists this afternoon and once again Monday amid
above normal daytime temperatures, especially today.

Very dry air aloft will mix down to the surface during daytime
mixing hours today. Minimum relative humidity values lower back
into the 20 to 30 percent range this afternoon and Monday
afternoon across the lower elevations. East-southeast winds will
continue to gust to between 15 and 25 mph at times across the
ridges.

Approaching clouds from the east-southeast may help to mitigate
such a rise in afternoon high temperatures on Monday afternoon.
However, enough low level dry air will still be present at the
top of the mixing layer that could be brought down to the
surface from daytime wind transport for minimum RH values to
once again bottom out in the 20s to low 30s.

The next potential chance for rain is Tuesday into Thursday in
association with a low pressure system originating in the
Atlantic, and then any potential lingering tropical moisture
associated with it. Confidence in placement of precipitation is
low at this time given model spread. The best chance of
beneficial rainfall will be along and east of the higher
terrain, but can`t rule out some beneficial rainfall farther
west.

&&

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

&&

$$

SYNOPSIS...TRM/JZ
NEAR TERM...MEK/FK
SHORT TERM...JP
LONG TERM...JP
AVIATION...JZ

FIRE WEATHER...MEK/FK/JP