683 
FXUS61 KRLX 120616
AFDRLX

Area Forecast Discussion
National Weather Service Charleston WV
216 AM EDT Fri May 12 2017

.SYNOPSIS...
Low pressure exits Friday. Next wave brings more rain Friday 
into Friday night. A new front well set up in or near the area 
over the weekend. High pressure builds early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 900 PM Thursday... 

Quasi stationary frontal boundary remains in the vicinity with
dewpoints in the 60s. This boundary will stay with us through
Friday. Models show some QPF overnight across the southern
portions of the area. Believe there will be a break in shower
activity overnight, then redeveloping Friday mid day. However,
kept likely to categorical PoPs across the extreme south per model
consensus. Adjusted hourly temperatures per recent sfc obs. Rest 
of forecast remains on track.


As of 140 PM Thursday...

No significant changes made since the 
update this morning. Upper shortwave trough over Indiana, making
its way towards the region, with convection slowly starting to 
fire up just to the west of the CWA. Still expecting showers and
thunderstorms to become more numerous as the afternoon and 
evening progresses, with heavy downpours, and the possibility 
for strong winds as winds strengthen in response to approaching 
shortwave. A slight risk for severe remains across the southern 
half of the CWA. 

The shortwave trough will move east of the area later this
evening, dragging a cold front across the area, and ending up
across extreme southern zones by Friday morning. This boundary
will lift back north a bit on Friday as a shortwave trough
deepens across the Mississippi Valley region, with additional
rounds of showers and thunderstorms, particularly across
southern and eastern zones. 

With the aforementioned in mind, decided to go ahead and extend
the flash flood watch in both area and in time to include
southwest VA and additional mountainous counties, and extend
until Friday night to account for additional convection on
Friday.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
As of 430 PM Thursday...

Period begins with inverted trough just east of the Ohio River,
an extension of a surface low to the south. Showers are likely 
to be ongoing from about the trough axis east, with the last of 
the thunderstorms over the far south, closest to the surface 
low.

This system moves off to the east Friday night and Saturday, as
an upper level northern stream trough digs in Friday night, and
then moves on to the east on Saturday. This will bring an end 
to the rain showers and flood threat from west to east Friday 
night, and then gradual clearing from west to east Saturday into
Saturday night.

High pressure builds toward the area from the southwest on
Saturday, but is then shunted off as a surface boundary sets up
along the southwest edge of upper level northwest flow. A
disturbance rising southeastward along this boundary may 
actually bring a return of rain showers late Sunday into Sunday 
night.

Central guidance temperatures accepted, which reflect a widening
diurnal range this weekend, with cool nights, but a warmer 
afternoon come Sunday.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As of 430 PM Thursday...

Long wave upper level ridging crosses early next week. That
should allow high pressure to bridge across if not dissolve a 
surface boundary. This will bring about dry weather, with a 
warming trend, through midweek. Increasing warmth and humidity 
on the back side of the ridge, and weak disturbances in the 
upper level southwest flow, may bring precipitation back to the
area Wednesday and Thursday, mainly in the form of the late day
shower or thunderstorm.

Central guidance temperatures accepted, reflecting a warming
trend including at night through midweek, with diurnal ranges
remaining large.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
As of 200 AM Friday...

Warm front will continue to meander across southern WV through 
15Z, after which it will take on more of an inverted trof 
oriented SW to NE through the region...in advance of a 
convective aided surface low. This means an abundance of low 
stratus through the morning hours for most terminals. The HRRR 
low level mass fields were relied on heavily for this TAF 
issuance...better capturing shifting low level wind resulting in
improving conditions for EKN by 09Z while lowering cigs into 
IFR at KCRW, KCKB, and KPKB while maintaining LIFR to IFR cigs 
at KBKW. Current thinking is enough of a puff in the low levels
will mitigate dense fog through the morning hours. 

Cigs will be slow to improve across central WV today given the
low level convergence affecting KCRW, while other terminals see
improving conditions through the morning hours. Scattered 
shra/tsra will develop in advance of the surface low across 
southern WV as the morning progresses with general shra 
overspreading the remainder of the area later in the afternoon. 
As the low works into the area, expect cigs to lower back into 
IFR for all terminals this evening and lowering into LIFR for 
sites east of the Ohio River. Vsby will also lower into general 
IFR.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SATURDAY...
     
FORECAST CONFIDENCE: Medium.

ALTERNATE SCENARIOS: Timing of improving cigs this morning may
vary a few hours at KCRW/KCKB/KBKW.

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 05/12/17
UTC 1HRLY       06   07   08   09   10   11   12   13   14   15   16   17
EDT 1HRLY       02   03   04   05   06   07   08   09   10   11   12   13
CRW CONSISTENCY  M    M    L    L    M    L    L    L    L    M    L    M
HTS CONSISTENCY  M    M    M    M    M    M    M    M    M    M    H    L
BKW CONSISTENCY  L    M    M    M    L    M    M    M    M    M    L    L
EKN CONSISTENCY  M    M    L    L    L    L    M    M    M    M    M    L
PKB CONSISTENCY  H    H    H    M    M    L    L    H    H    M    H    L
CKB CONSISTENCY  H    M    M    M    M    H    L    L    M    M    M    M

AFTER 06Z SATURDAY...
IFR possible into Saturday as rain Friday night gives way to
stratus.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...Flash Flood Watch through this evening for WVZ005-006-013>015-
     024>027-033-034-515>524.
OH...None.
KY...Flash Flood Watch through this evening for KYZ102-103-105.
VA...Flash Flood Watch through this evening for VAZ003-004.

&&

$$
SYNOPSIS...RPY/30
NEAR TERM...30
SHORT TERM...TRM
LONG TERM...TRM
AVIATION...30