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-- Discussion containing changed information from previous version are highlighted. --
262
FXUS61 KRLX 221430
AFDRLX

AREA FORECAST DISCUSSION
National Weather Service Charleston WV
1030 AM EDT Wed May 22 2019

.SYNOPSIS...
Much warmer today into the weekend with chances for showers and
thunderstorms somewhere in the area each day.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1027 AM Wednesday...

Minor adjustments made to hourly temps for this morning, owing
to rapid warming that is occurring. Otherwise, no changes needed
to inherited forecast at this time. May need to expand POPs
across the N/NW CWA a little farther southward late this
afternoon, but will await for analysis of incoming 12z guidance
suites before making and changes to precip chances this
afternoon.

As of 635 AM Wednesday...

Forecast on track with upper level ridge overhead, but on its
way out.

As of 315 AM Wednesday...

Upper level ridge exits this morning, allowing a weak mid level
short wave trough to traverse the mid and upper Ohio Valley this
afternoon and evening. Dew point pooling in this area along and
southwest of a warm front lifting toward the PA/OH state line
will contribute to CAPE values up to 1.5 KJ/kg during peak
heating. Bulk shear values into the 30s suggest a marginal risk
for severe thunderstorms as depicted by SPC, but 0-3km SRH
values possibly as high as 300 m2/s2 also suggest rotating
updrafts.

The weakness of the wave and lack of deep layer moisture
suggested only isolated to scattered coverage, but PW values are
progged as high as 1.5 inches, so locally heavy downpours are
possible.

The remainder of the area will have a summer likely day,
noticeably warmer than Tuesday, with highs topping out some 15
degrees higher. Opted to stick with the previous forecast for
highs, in line with MOS but slightly higher than central
guidance,

Any thunderstorms will weaken with loss of heating tonight as
they move east across the northern tier and into lower dew
points. Otherwise southerly flow will make for a warm night with
lows close to central guidance and MET and higher than the MAV
even in the valleys.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
As of 348 AM Wednesday...

The potential for severe weather will be the main focus on Thursday.
Upper level ridge in place across the southeast CONUS will get
briefly shunted southward due to the presence of a shortwave trough
that will be moving across Ontario through the day. As the ridge
axis pushes southward, a belt of westerly mid-level flow of 55-60
kts will stream across the region, particularly northern areas
of the CWA where the winds aloft will be stronger. Shortwave
energy embedded in the westerly aloft will provide forcing for
ascent; while at the surface, a cold front will move across the
region Thursday afternoon into the evening as the shortwave
trough and associated surface low move eastward into Quebec.
With our region in the warm sector for much of the day,
dewpoints will rise to the upper 60s with some areas reaching
70F in the afternoon. This will combine with daytime heating to
support MLCAPE values in the 2,000- 3,000 J/kg range. In
addition, 0-6 km Bulk shear values will be around 40-50 kts,
with the higher values more common in the northern portions of
the CWA. Due to the stronger dynamics, greater instability, and
better forcing in the northern areas, SPC has issued a slight
risk for severe storms generally along and north of a line from
Ironton to Sissonville to Mill Creek. A marginal risk then
covers the remainder of the CWA, with the exception of MCDowell
county and our SW VA counties. In regards to the greatest
hazards with Thursday`s storms, latest forecast soundings
indicate that DCAPE values could be in the 900-1000 J/Kg range,
suggesting that strong straight-line winds would be the primary
threat with this activity. Hail will also be a concern given the
instability expected, and suppose a tornado threat can`t be
completely ruled out with 0-3 km SRH values in the 200-250 m2/s2
range; suggesting that some rotating updrafts will be possible.

The cold front will mostly push east of the region by Friday
morning, however, models suggest that the boundary may stall across
southern areas providing just enough of a focus for isolated showers
and storms Friday. Given the dry atmosphere in place as the ridge in
the southeast builds northward into the region on Friday, any
chances for convection will be small and currently just have low
slight POPs across the southern coal fields and into SW VA where
just enough lift may be present as the frontal boundary lingers in
the region. Regardless, a mainly dry and warm day is expected with
highs in the mid to upper 80s across most of the region.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 348 AM Wednesday...

Warm and humid conditions will continue into the weekend as the
persistent upper ridge remains in place in the southeastern CONUS.
Saturday will be toasty with widespread highs in the upper 80s
and approaching 90 in many locations. The threat for
precipitation will once again increase as a low pressure system
moves across northern Ontario and a trailing cold front moves
eastward across the Ohio Valley. Aloft, embedded disturbances
will move along the northern periphery of the ridge and interact
with the frontal boundary to support a mention of showers and
storms. The highest POPs Saturday afternoon will be near the
mountains, aided by the orographic influence, but there will at
least be a chance of a shower or storm elsewhere given the warm
and humid airmass in place.

Coverage of showers and storms will increase by Sunday as the east
to west oriented frontal boundary lingers in the Ohio Valley
and disturbances embedded in the zonal flow aloft move through.
Currently have chance POPs across the majority of the region for
better confidence in greater storm coverage on Sunday, and even
low likely POPs in northern areas that will remain closer to
the stalled boundary. Temperatures remain above seasonal with
highs in the mid 80s across the area.

It will remain unsettled into the new week as the active
westerly flow aloft continues with a continuation of showers and
storms.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
As of 635 AM Wednesday...

VFR conditions can be expected through the period, with the
possible exception of showers or thunderstorms late this
afternoon into tonight over the middle Ohio Valley.

Light east surface flow across the lowlands early this morning
and southeast flow across the mountains, a bit gusty on the
ridges, will become south 5 to 10 kts throughout the area today,
and continue through tonight. Flow aloft will be moderate
southwest.

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

FORECAST CONFIDENCE: High.

ALTERNATE SCENARIOS: A thunderstorm may impact PKB or CKB late
this afternoon into tonight. MVFR stratocu may approach BKW
from the southeast tonight.

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       12   13   14   15   16   17   18   19   20   21   22   23
EDT 1HRLY       08   09   10   11   12   13   14   15   16   17   18   19
CRW CONSISTENCY  H    H    H    H    H    H    H    H    H    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    M    M
EKN CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
PKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H

AFTER 12Z THURSDAY...
Widespread IFR conditions are not expected at this time.

&&

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

&&

$$
SYNOPSIS...TRM/MZ/RG
NEAR TERM...RH/TRM
SHORT TERM...RG
LONG TERM...RG
AVIATION...TRM