Area Forecast Discussion
Issued by NWS Blacksburg, VA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS61 KRNK 191201
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
701 AM EST Tue Feb 19 2019

.SYNOPSIS...
Low pressure will track from near the mouth of the Mississippi River
this morning to across the Carolinas by Thursday morning.
Moisture associated with this system will bring a swath of
significant wintry weather to the area Tonight into Wednesday
evening. Our weather pattern will remain on the wet side for the
remainder of the week into the weekend as a series of fronts
and low pressure systems track through the region.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 400 AM EST Tuesday...

Deep cold air damming pattern continues to develop today with a
sharp western edge as high pressure centered over the Ohio Valley
this morning builds south into the Mid Atlantic region. Surface dew
points have the potential to lower into the teens, especially
north of Route 460 which would give more room for evaporative
cooling once the precipitation does begin tonight. Batch of
lower clouds from northern Virginia into eastern Kentucky is
forecast to erode this morning, but by then high clouds will
already be filling in from the south so only limited heating
today.

Synoptic and high resolution models showed good consensus with the
evolution of the approaching precipitation tonight. Guidance has the
winds picking up from the southeast in the mountains of northwest
North Carolina around 23Z/6PM. This will be the leading edge of the
precipitation that will advance northeast reaching Hot Springs and
Buckingham by midnight.

Axis of strongest lift and higher precipitation amounts lifts across
the Tennessee Valley and into the central Appalachians from 00Z-
12Z/7PM tonight through 7AM Wednesday with impressive isentropic
lift in the 290-300K layer. The southeast winds increase to just
over 50 knots overnight at 850MB and this upslope will enhance
precipitation amounts along the Blue Ridge and in the eastern
foothills.

For precipitation type, most locations will be starting as rain or
snow then transition to freezing rain. The timing of the
transition will occur from southwest to northeast and starting
in northwest North Carolina in the evening and reaching the
Alleghany Highlands late tonight. Bufkit showed the GFS slightly
weaker and definitely slower with the northern expansion of the
warm nose aloft than the NAM, HiRes-NMM/ARW and the HREF
guidance. Will be using a temperature profile in line with the
3KM NAM for precipitation type and timing.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 400 AM EST Tuesday...

Winter storm warnings and advisories continue into Wednesday night.

Low pressure over North Carolina Wednesday morning will move east
Wednesday afternoon into Wednesday night. The cold air damming will
be slow to erode Wednesday afternoon into Wednesday night. It will
take quite some time for the freezing rain to completely transition
to rain. Cold pockets might persist even longer than forecasted.

Used a non diurnal curve for Wednesday with temperatures slow to
rise with strong damming. High temperatures for Wednesday will range
from the lower 30s in the north to the mid 40s in the far western
mountains. For ptype used the Mixed precip_topdown_ensemble tool
with model choice of blend of ECMWF and NAM. For QPF used WPC with
shaping for vertical velocity and upslope terrain effect. Decrease
pops a little in the west Wednesday morning to account for the NAM
placement of better lift. Increased wind speeds in the west to
capture the healthy 850mb jet will pivots across our forecast area.
At this time, looks like wind gusts will be below wind advisory
levels.

Another surge of moisture/rain will arrive with a front Wednesday
night under warm advection. Low temperatures Wednesday night will
vary from the lower 30s to the lower 40s.

There is a shift in the precipitation southward Thursday to over the
northern Gulf Coast states into central NC, with 1026 high over
Illinois/Iowa ridges southeast over the central Appalachians.
Blended in the NAM to capture some cooler temperatures for Thursday.
High temperatures Thursday will generally be from the lower 40s in
the northwest to the mid 50s in the south. The flow of moisture
buckles north Thursday night with southern stream energy. Low
temperatures Thursday night will range from the lower 30s in the
north to the lower 40s in the south.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 400 AM EST Tuesday...

The high moves across the Great Lakes and off the mid-Atlantic coast
Friday into Saturday with battle ground of precip aimed along a
front from east Texas to the Carolinas/southern Mid-Atlantic.

Most of this will be liquid as warmer air aloft wins out. Will see
showers with a cold front Sunday with precip and front pushing
southeast and east Sunday night, setting up for a dry Monday.

Overall rainfall totals have dropped some, but will still need
to monitor potential for flooding given saturated the ground is.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
As of 655 AM EST Tuesday...

Batch of MVFR clouds from northern Virginia into eastern
Kentucky is forecast to erode this morning, but by then high
clouds will already be filling in from the south. Ceilings will
lower from southwest to northeast as precipitation spreads
across southwest Virginia, northwest North Carolina and
southeast West Virginia. Synoptic and high resolution models
showed good consensus with the evolution of the approaching
precipitation tonight. This will be the leading edge of the
precipitation reaching KBCB just after 00Z/7PM and KLYH around
midnight. Precipitation will begins as rain or snow then
transition to sleet then freezing rain by early morning. Light
to moderate accumulations of snow, sleet and ice are expected.

Guidance has the winds picking up from the southeast in the
mountains as a strong low level jet moves into the area after
00Z/7PM. Winds at KBLF may gusts as high as 35 knots overnight.

Confidence in the aviation forecast is above average.

Extended Aviation Discussion...

Wintry precipitation will gradually transition to all rain from
south to north by early Wednesday evening as warmer air
arrives. Expect widespread sub-VFR conditions through much of
the day.

A frontal boundary will meander around the region into the start
of the weekend, along with several areas of low pressure moving
along this boundary. This will keep the potential for
rain and sub-VFR conditions across the area through Saturday.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Winter Storm Warning from 6 PM this evening to 8 PM EST
     Wednesday for VAZ014-017-018-022-032-033.
     Winter Storm Warning from 6 PM this evening to midnight EST
     Wednesday night for VAZ019-020-023-024-034-035-045>047.
     Winter Storm Warning from 6 PM this evening to 4 PM EST
     Wednesday for VAZ010>013-015-016.
     Winter Weather Advisory from 6 PM this evening to noon EST
     Wednesday for VAZ007-009.
     Winter Weather Advisory from 6 PM this evening to 6 PM EST
     Wednesday for VAZ043-044-058-059.
NC...Winter Storm Warning from 6 PM this evening to 4 PM EST
     Wednesday for NCZ001>003-018-019.
     Winter Weather Advisory from 6 PM this evening to 6 PM EST
     Wednesday for NCZ004>006-020.
WV...Winter Storm Warning from 6 PM this evening to 8 PM EST
     Wednesday for WVZ044.
     Winter Storm Warning from 6 PM this evening to midnight EST
     Wednesday night for WVZ507-508.
     Winter Storm Warning from 6 PM this evening to 4 PM EST
     Wednesday for WVZ042-043.

&&

$$
SYNOPSIS...DS/KK
NEAR TERM...AMS
SHORT TERM...KK
LONG TERM...KK/WP
AVIATION...AMS/NF


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.