Area Forecast Discussion
Issued by NWS Blacksburg, VA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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
846
FXUS61 KRNK 271205
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
705 AM EST Mon Feb 27 2017

.SYNOPSIS...
High pressure over the area today will drift east as a weak
upper-level disturbance passes to the north of the area by
tonight. A warm front will lift north through the area Tuesday
followed by a strong cold front late Wednesday. Cold high
pressure will build in for the end of the week into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 330 AM EST Monday...

Canadian high pressure will drift east of the Mid-Atlantic
seaboard by afternoon as a weak upper-level disturbance,
embedded within the westerlies and ahead of a much stronger
deepening disturbance in the western U.S. moves east-northeast
from the western TN Valley into the OH Valley by Monday morning.
With respect to precipitation, the main thrust of this system
will be to our north, with perhaps a few sprinkles across the
west and northwest parts of the CWA overnight into early
Tuesday. As the system tracks to our northwest, the
surface/boundary layer across our area will be fairly dry as a
result of the antecedent high pressure system. The upper-level system
will be north of the area by Tuesday morning. As the upper flow
amplifies in response to the strong Pacific system moving
inland, ridging in the eastern U.S. will push a warm front
northward through the area Tuesday. This warm front will be
located across northern GA into northern SC/southern NC by 12Z
Tuesday. Patches of light rain will begin spreading northward
through the counties along/southeast of the Blue Ridge by that
time. Through this portion of the forecast period, QPF will
generally be just a few hundredths of an inch at best and
generally confined to areas south-east of the Blue Ridge with
the warm front early Tuesday and/or west of I-77 with the weak
upper disturbance later today/tonight.

With respect to temperatures, expect a big warmup this period to
well above normal temperatures as we move into Tuesday and
Wednesday. Decoupling and radiational cooling, despite
increasing cloud cover, has allowed many areas to drop into the
mid and upper 20s this morning. However, this will be the last
morning below freezing until the later part of the week. 850mb
temps, starting out below 0C across most of the CWA early this
morning, will quickly surge into the +12C to +14C range by
Tuesday afternoon. This will yield high temperatures about 10
degrees above normal today and even warmer 60/70 degree readings
for Tue and Wed.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
As of 330 AM EST Monday...

Approaching long wave 500 MB trof and southeast ridging will result
in broad southwest flow Tuesday through Wednesday when the next
strong cold front comes through. No organized short waves but
enough prolonged warm air advection and modest isentropic lift
along with increasing moisture will lead to periods of showers.
By Tuesday night precipitable water values are around inch.

Maximum temperatures will be above normal on Tuesday and even warmer
ahead of the front on Wednesday with 850MB temperatures closing in
on +15C. Have kept minimum temperatures on Tuesday night on the
warmer side of guidance, with the region still being in the
warm sector.

Models still show a spread in the timing of the front on
Wednesday with the GFS the fastest, and roughly 6 hours ahead of
the NAM. ECMWF was a compromise between the two. Similar to WPC
recommendation, have leaned toward the NAM/ECMWF solution. This
brings the front across the central and southern Appalachians
between 18Z/1PM Wednesday and 06Z/1AM Thursday. Will have the
highest probability of precipitation on Wednesday afternoon and
evening.

Winds pick up from the northwest behind the front with a 50 knot
850MB jet and pressure rises up to +10MB/6hrs. Will be increasing
sustained winds and gusts in this time frame.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
As of 330 AM EST Monday...

A northern stream front moves across Friday morning. Appears
moisture and lift will be further north of the forecast area, but
some rain and snow showers could spill into the mountains of WV to
the Alleghanys.

Strong high pressure works in from the Midwest for Saturday,
then shifts south across the southeast U.S for Sunday. After a
period of cooler temperatures near to just below normal Thu-Sat,
we will warm back up for Sunday.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
As of 650 AM EST Monday...

A weak upper-level disturbance will move from the western TN
Valley toward the eastern OH Valley through early Tuesday Mid
and high clouds will accompany this feature with possibly a few
sprinkles across the Alleghanys today into tonight. Otherwise,
the period is expected to be mostly VFR with ceilings at or
above (AOA) 050 through the TAF valid period, but mostly BKN-OVC
at these levels throughout the TAF valid period, possibly SCT at
times for KLYH and KDAN. The lower-level air mass is expected to
remain too dry for fog development and rain is not expected to
be significant enough to saturate the lower-level air mass to
generate fog. With Canadian high pressure moving off to the east
of the region, winds will come around to the SSW-SSE through the
period at speeds of 5-10 mph, with some low end gusts possible
west of the Alleghany front by afternoon.

Extended Aviation Discussion...

A warm front across the southeast states will lift northeast
Tuesday before passing to the north of the area on Wednesday.
An increase in low-level moisture will likely result in
increased likelihood of MVFR cigs as we move through the day
Tuesday, especially along and near the Blue Ridge with moist
southeast flow. A few light rain showers may also accompany the
front.

A cold front pushes east into the area Wednesday into Wednesday
night with potential for more widespread MVFR/IFR in showers
and thunderstorms. A west to east moving squall line with strong
to possibly severe thunderstorms, perhaps a QLCS type convective
configuration, will be possible late Wednesday into Wednesday
evening in advance of the front. Strong northwest winds along
with mountain sub-VFR in upslope low clouds and light precip
will likely follow the front for much of Thursday. Expect
downslope drying to return VFR to eastern locations by Thursday
afternoon with this trend lingering across eastern sections
through the end of the week. However another weak clipper area
of low pressure looks to track just north of the region by
Friday with possible mountain MVFR in at least upslope
cloudiness, and possible light precipitation western ridges
later Thursday night into Friday.

&&

.CLIMATE...
As of 330 AM EST Monday...

Record warm Mins for March 1

Roanoke.....52 in 1918
Lynchburg...57 in 1910
Danville....51 in 2012
Blacksburg..45 in 1997
Bluefield...56 in 1997

Record highs for March 1

Roanoke.....76 in 1972
Lynchburg...78 in 1918
Danville....80 in 1972
Blacksburg..72 in 1976
Bluefield...78 in 1997

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.

&&

$$
SYNOPSIS...RAB
NEAR TERM...RAB
SHORT TERM...AMS
LONG TERM...AMS/WP
AVIATION...RAB
CLIMATE...AMS



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