343 
FXUS61 KRLX 171005
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
605 AM EDT Fri Mar 17 2017

.SYNOPSIS...
High pressure exits first thing this morning. Warm front 
late today, followed by a cold front late tonight into 
Saturday. Disturbance Saturday into Saturday night.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 600 AM Friday...

Temperatures continue to run a little low early this morning.
Forecast otherwise appears to be on track including timing of 
precipitation.

As of 225 AM Friday...

High pressure exits first thing this morning. An upper level 
short wave trough digs east-southeastward through the midwest 
today and tonight, and becomes a closed upper level low 
overnight tonight. This drives a surface warm front through the
area late today into tonight, and then a surface cold front 
into the area late tonight.

A narrow north-northwest to south-southeast oriented band of
precipitation was having trouble reaching the ground south of
Chicago early this morning, where the band was thinnest. The 
models appeared to have a good fix on this precipitation 
entering the area during the daylight morning hours, the band 
widening in an area of developing warm advection / isentropic 
lift. The only gradually increasing PoPs reflect the 
precipitation having difficulty reaching the ground early on, 
with rain becoming likely from west to east across the area 
this afternoon.

Blended in the latest MET and short term consensus into the 
previous forecast, which already looked reasonable, for 
temperatures and dew points today and tonight. These 
temperatures and model fields suggest temperatures climb above 
freezing at the surface before doing so in the elevated warm 
wedge, which should mitigate the chance for freezing rain. 
Instead, a light mix of snow and sleet may or may not measure 
this morning, before the transition to rain this afternoon, when
measurable precipitation becomes likely.

A slower rise in surface temperatures than forecast could
increase the chance for freezing rain today. The daytime timing
in mid March does not favor freezing rain but, if precipitation
is able to reach the ground early this morning, then the chance
for freezing rain could increase.

As the cold front pushes into the area late tonight, drier air 
arriving aloft will eliminate ice crystals and, with surface 
temperatures above freezing through the night, the diminishing 
showers should remain in the form of rain in the wake of the 
cold front over the middle Ohio Valley.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
As of 225 AM Friday...

Cold front just to the east of the CWA at the start of the period, 
with gradually cooler weather taking hold. Light snow shower 
activity will kick off particularly later in the day Saturday and 
Saturday night, as a northwesterly upslope flow, and several upper 
impulses rotate around the back side of an upper low, which will be 
moving across the Great Lakes region towards the east coast. At this 
point, figuring mainly light accumulations across the northern 
mountain zones, with little to no accumulations across the lowlands, 
with the bulk of accumulations expected Saturday night and Sunday.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 225 AM Friday...

High pressure with dry and warmer conditions to start next week, 
Another cold front will sweep across the area by Monday night, with 
rain showers developing area wide as it does so. Frontal boundary 
sags south by late Tuesday night, with high pressure building in 
across the north, with much drier air in place. There could be a 
rumble of thunder late Monday night/early Tuesday across far 
southwestern zones, but threat appears minimal at this point. A 
strong low pressure system is progged to move into the area by late 
next week, with the potential for heavier rains, and
thunderstorms.

&&

.AVIATION /10Z FRIDAY THROUGH TUESDAY/...
As of 600 AM Friday...

After a VFR start, a warm front will bring lowering ceilings 
today, along with precipitation that may start briefly as a mix 
of snow and sleet, before transitioning to all rain. By the time
the probability of precipitation is high enough to code up 
explicitly in the TAFs this afternoon, it should be in the form 
of all rain.

Visibilities are likely to drop to MVFR in rain late this 
afternoon into this evening. Later tonight, the combination of 
the warm front moving through, and the loss of daytime mixing, 
is likely to result in MVFR ceilings. Ceilings may drop into IFR
overnight tonight in the mountains, and in the PKB area of the 
middle Ohio Valley.

A cold front will move into the area late overnight. More
widespread IFR conditions are likely behind it.

Light and variable surface flow ahead of the warm front will
become light southwest behind the warm front late today and 
tonight, followed by a subtle shift to light west to southwest
as the cold front crosses toward dawn Saturday. Light west flow
aloft early this morning will become moderate southwest later 
this morning, and then moderate west tonight.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SATURDAY...
     
FORECAST CONFIDENCE: High early on, then becoming medium by 
late today.

ALTERNATE SCENARIOS: Timing of precipitation and associated category
changes may vary. If confidence increases, may need to add a 
brief period of wintry mix at the start of the precipitation
today. Timing and extent of IFR ceilings tonight may vary, and
some IFR visibility cannot entirely be ruled out.

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                                             FRI 03/17/17
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    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  H    H    H    H    H    H    H    H    H    H    H    M
PKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    M
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    M

AFTER 12Z SATURDAY...
IFR possible in in low clouds early Saturday morning, especially
in and near the mountains. IFR also possible Saturday night into
Sunday morning, in snow showers in the mountains, and in low 
clouds throughout the area.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...None.
OH...None.
KY...Freeze Warning until 9 AM EDT this morning for KYZ101>103-105.
VA...None.

&&

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