Area Forecast Discussion
Issued by NWS Charleston, WV-- Highlight Changed Discussion --
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FXUS61 KRLX 201631
Area Forecast Discussion
National Weather Service Charleston WV
1231 PM EDT FRI MAY 20 2016
Low pressure approaches evening and moves through tonight...then
shifts to our southeast on Saturday. Heavy rain threat exists late
tonight mostly for Ohio River Valley counties.
.NEAR TERM /THROUGH TONIGHT/...
A Low pressure system intensify as the first vorticity lobe
crosses the area by this evening. Models indicate that a series of
vorticity lobes will move around the low to keep the atmosphere
unstable through Sunday.
Radar images show stronger convection is over central KY moving
north. This batch of PCPN will eventually drift east and affect
southeast OH and portions of WV tonight. Models indicate
precipitable water of 1.5 inches, poor sfc based CAPE and marginal
deep layer shear of 35 knots. Do not see any report upstream and
lightning density is diminishing. Will continue monitoring
rainfall estimates and flash flood guidance to anticipate any
Light to moderate rain will affect southeast OH this evening, and
the rest of WV overnight. Used the superblend and, bias corrected
SREF for temperatures through the period.
.SHORT TERM /SATURDAY THROUGH MONDAY/...
Main swath of 850mb Theta E convergence will have lifted well to the
northeast of the CWA by Saturday morning...so the short term will be
primarily dealing with the upper trough at 500mb with the extra lobe
dropping in from the north for Saturday night. By and large...this
will end up as the cold pool convection period as the surface low
regenerates along the mid atlantic coast and the aforementioned
500mb low all but stalls over the Delmarva Peninsula.
In the forecast grids...this has necessitated an increase of the
POPS back to the west for Sunday to low end chance that will peak
with the heating of the day. Could be difficult to get rid of the
isolated showers over the northeast mountains because of the
behavior of the upper level low...so those low chances will outrun
the lowlands from a time standpoint...lingering into Monday...as
high pressure tries to regain control.
Temperatures continue to be held in check given the lowering
heights...with slightly below average values across the board.
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
SFC high pressure will push into the region for the start of the
new work week. This will give us some dry and warm conditions
through at least mid week.
Guidance is indicating a stationary boundary drifting over the
region by Wednesday or Wednesday night and this will not move
much through the end of the week. Several transitioning shortwaves
will bring the threat for showers and thunderstorms into Friday.
.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
A sfc high pressure remains in control across the area through
this afternoon. Weather deteriorates as deep low pressure system
cross our area through tonight and Saturday.
High resolution models are in agreement with the timing of PCPN
reaching southeast OH and portions of southern WV through this
Once the rain showers pass by, low level stratus will be common at
most sites. Models bring the low pressure center over northern KY.
expect this low to move overhead to produce numerous showers with
embedded thunderstorms. Expect minor water problems by Saturday
evening. PCPN may continue after the front through Sunday as the
upper level low/trough pass by.
Despite or the abundant humidity, calm winds once the atmosphere
decouples, boundary layer and H925 level increase 30-40 knots
preventing fog development.
Low level stratus could produce periods of mvfr/ifr overnight.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SATURDAY...
ALTERNATE SCENARIOS: Duration of the heavier showers late this afternoon and
this evening at any one location could be less than window mentioned in tafs.
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 15 16 17 18 19 20 21 22 23 00 01 02
EDT 1HRLY 11 12 13 14 15 16 17 18 19 20 21 22
CRW CONSISTENCY H H H H H H H H M M M M
HTS CONSISTENCY H H H H H H M M M M M M
BKW CONSISTENCY H H H H M M M M M M M M
EKN CONSISTENCY H H H H H H H H H M M H
PKB CONSISTENCY H H H H H H H H H M M M
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 18Z SATURDAY...
Widespread IFR conditions possible overnight Saturday night into
Sunday morning under heavier showers.