Area Forecast Discussion
Issued by NWS Charleston, WV

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FXUS61 KRLX 271332
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
932 AM EDT FRI MAY 27 2016

.SYNOPSIS...
A few weak disturbances aloft within upper level ridge. Slow
moving convection with heavy downpours today and Saturday.
Southeast flow will raise shower chance Sunday mainly mountains.

&&

.NEAR TERM /THROUGH TONIGHT/...
930 AM update...no significant changes. -shra this morning near
the Ohio River gradually starting to dissipate. Still looking at
diurnal convection firing up this afternoon in the warm moist
unstable atmosphere...with brief heavy downpours.

PREVIOUS DISCUSSION BELOW...

As for today...The upper ridge just off the SE coast tries to flex
more of its muscle into the region. There appears to be a weak
axis of lift/moisture on the w peripheral of said ridge which
will try to push into the mountains later this aftn as the ridge
flexes into the area. This in conjunction with some SE flow
providing for some orographic enhancement...will mean for sct
shra/tsra this aftn and early eve in the mountains. Not much
change in pops inherited from the day shift with a solid 40 to 50
pop in the mountains with isolated mention outside of the
mountains. The mountain convection will try to spill off westward
into central WV during the early eve hrs. Hard to figure out just
how much will survive but current thinking is best chance may lie
over E KY...but confidence is too low to insert any higher than
low chance. Being under the influence of the upper ridge means for
a very light flow regime up thru a portion of the mid levels. As
such initial convection over the mountains this aftn will stand up
and struggle to maintain updrafts...essentially raining themselves
out...meaning downpours are likely in any mountain convection. As
for temps today...elected to go a few degrees below guidance
outside of the mountains...mainly due to soil moisture from the
wet month thus far. Light SE flow will try to counteract that a
bit with compressional warming...but still think 88 to 90 will be
tough to breach.

Any eve shra/tsra over NE KY/SE OH this evening will quickly wane
with another summer like night in store.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
A summer like pattern with weak and ill defined upper flow continues
for Saturday. Despite the summer like warmth and moisture in a deep
but weak south to southeasterly flow...with surface high pressure
centered off the Mid Atlantic coast...it looks like the dominant
synoptic feature will an upper ridge over the area. Thus...with
little discernible upper disturbances to help set convection
off...will try to be deterministic and focus on diurnal summertime
climatology for Saturday...with emphasis on the mountains in
southeasterly flow. Thus...will go with slight chance of afternoon
convection in the west...and the best chance for afternoon
convection in the mountains. Any convection that forms over the
mountains will tend to propagate northwestward into the low lands
before dissipating Saturday evening. Should be more sunshine
Saturday to go on the higher end of temperature guidance...in the
mid to upper 80s...but still tempered by the lush vegetation and
moisture. A muggy and uneventful Saturday night is in store once
any lingering convection dies Saturday evening.

For Sunday...a bit of a change per general model agreement. The long
forecast system drifting northwestward to the southeast U.S.
Coast saturday will then drift north northwestward Sunday.
Whether the surface system makes it to us or not...the supporting
weak negatively tilted upper trough pulls even deeper moisture
into our region. This brings a better chance for showers and
storms...again mainly over the mountain counties. More clouds and
showers mean slightly cooler highs on Sunday. For Sunday
night...the northern stream looks to drop south just enough to
keep the best chance for convection over the mountains.

A weak cool front will accompany the amplifying northern
stream...pushing southeast across the area Monday. Again...the best
chance for convection remains over the mountains in the deepest moisture.
Finally some drying looks likely from northwest to southeast
during Monday behind the front...but still quite warm with highs
in the 80s.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
Upper level ridging rebuilds for a dog day summer pattern in the
middle of next week, with diurnally driven thunderstorms.

An upper level low is progged to roll across southern Canada later next
week. It may get close enough to drive a cold front toward the
area Day 7 night, so have chance pops persisting next Thursday
night.

Trended temperatures, mainly highs, down a bit per national
guidance in this dirty ridge pattern.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
Scattered convection is expected this afternoon across the
mountains...perhaps spilling into the lowlands this evening before
waning. At this distance...given only modest confidence of hitting
a mountain taf site...have kept mention out of taf attm.

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

FORECAST CONFIDENCE: Medium to high.

ALTERNATE SCENARIOS: Timing mountain convection may vary an hour
or two. KBKW/KEKN could be impacted by convection late this
afternoon.

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  M    H    H    H    H    H    H    H    H    H    H    H
HTS CONSISTENCY  M    M    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  M    M    H    H    H    H    H    H    H    H    H    H
PKB CONSISTENCY  M    M    H    H    H    H    H    H    H    H    H    H
CKB CONSISTENCY  M    H    H    H    H    H    H    H    H    H    H    H

AFTER 12Z SATURDAY...
No widespread IFR conditions expected.

&&

.HYDROLOGY...
The river gauge...and forecast point...at the South Side Bridge
in downtown Charleston has not be reading correctly. The NWS
hydrologist is working to correct this problem.

&&

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

&&

$$
SYNOPSIS...JMV/30
NEAR TERM...SL/30
SHORT TERM...JMV
LONG TERM...TRM
AVIATION...30

HYDROLOGY...



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