864
FXUS61 KRNK 080324
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
1024 PM EST Fri Feb 7 2025

.SYNOPSIS...
Saturday will provide another chance of rain and freezing rain for
the region. Flood Watches and Winter Advisories have been issued for
this weekend due to ice and excessive rainfall threats. Additional
rounds of storms next week provide multiple opportunities for rain
and wintry precipitation.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 1015 PM EST Friday...

Key Messages:

1) Another chance of wintry precipitation Saturday.

2) Flood Watch and Winter Advisories for Saturday for northern
counties.

Rain is developing across KY associated with increasing
isentropic lift. This precipitation will overspread the region
after midnight, primarily impacting West Virginia and Virginia,
with p-type in the form of freezing rain where temperatures are
32 deg F or less. The evening RNK sounding revealed a warm nose
of +7 deg C at 850 mb. This supports melting of all dendrites
making p-type contingent on the actual surface temperature.
With surface air temperatures in the 30s and dewpoints in the
20s, should be easy to wetbulb surface temperature AOB freezing
during precip production later tonight.

No changes planned for the evening update with respect to
current winter weather advisory headline or the flood watch, but
do feel there will be some light icing farther south into the
higher elevations of the New River Valley and Blue Ridge
Parkway, but limiting factor there will be the overall QPF which
is expected to be less than a tenth of an inch. Road/ground
temperatures have been warm of late, so thinking most of the ice
would be elevated, with exception of where temperatures dip into
the U20s, then all surfaces in-play.

Confidence is high that light-moderate icing will occur late
tonight through mid-day Saturday for our northern counties
primarily along the I-64 corridor...amounts 0.10 to 0.20.
Confidence is lower farther south, but do feel (similar to the
last event) that light icing possible along the spine of the
Blue Ridge Parkway into Floyd and Patrick Counties, but mainly
on elevated surfaces such as trees and powerlines. Again,
temperature is critical here.

Isentropic lift will support stratiform precipitation for most
of the region Saturday, but favoring the northern Mid-Atlantic.
Farther south, NC counties may not see much at all.

A Flood Watch has been issued for northern counties in WV and
VA due to the amount of rain they have already received and to
account for the additional rain possible tomorrow. QPF from this
event is expected to range from 0.25 to 0.75 north of highway
460 and less than a tenth of an inch elsewhere.  This does not
sound like much, but 0.75 falling on already saturated ground in
less than an hour will runoff quickly.

With respect to timing. Onset looks to be Midnight-4AM time
frame depending on specific location, BLF first in-line.

Temperatures Saturday will be slow to rise due to cloud cover,
but do think that most areas climb above freezing during the
afternoon. Hold-outs may be the higher terrain from LWB-LEX
where ridges may remain near 32 for most of the day. West of the
Appalachian Divide, warm air advection from the TN valley should
push temperatures well above freezing...both the MET/MAV MOS
suggesting Bristol reaches 65 degrees. Not as dramatic, but for
areas across the Carolinas where it does not rain, temperatures
should test the 50s.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As OF 200 PM EST Friday...

Key Messages:

1). Very unsettled with precipitation expected most every day,

2). Winter precipitation possible at times, with accumulating
snow possible especially Tuesday-Wednesday.

3). Repeated rounds of moderate to heavy rainfall likely through
the period. Areal and river flooding likely.

Very unsettled weather pattern unfortunately expected to remain
in place through the period. A highly kinematic zonal flow with
active southern stream short waves will continue to traverse the
area in rapid succession. Meanwhile, enough cold air gradually
filters down from Canada to introduce the threat for some winter
precipitation at times. The bottom line is that a baroclinic
zone will linger over or near the area throughout the week with
the disturbances riding along the front. There will be a sharp
gradient in temperatures across the boundary from the 20s and
30s to the north to the 50s and 60s to the south. The boundary
location will be critical in delineating where the winter
precipitation will be versus all liquid precipitation.

Given the antecedent saturated soil conditions, rainfall will be
a problem, especially west of the Blue Ridge. The cumulative
effects of the repeated rounds of rainfall will acerbate the
problems as the week progresses with significant flooding
possible by the end of the week. At this point there appear to
be at least five notable rainfall events next week. Total
rainfall amounts for next week could exceed 5 inches, especially
during the later half of the week.

For this time frame, look for a warm frontal/isentropic rain
event to bring 1/2 to 1 inch of rain to the region followed by a
weak push of the frontal boundary to the south by Sunday. The
front returns back to the north with the next round of rain by
Monday. This rain event should bring another 1/2 to 1 inch of
rainfall to most areas.

Temperatures look to be mostly below normal through the period
with highs in the 40s most areas and lows in the 20s and 30s.

/Confidence Levels in Forecast Parameters/
- Moderate Confidence in Temperatures,
- High Confidence in Precipitation Probabilities,
- Moderate Confidence in Wind Direction and Speed.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 215 PM EST Friday...

Key Messages:

1). Very active weather expected through the period with heavy
rainfall/flooding and winter precipitation issues expected.

2). Winter precipitation likely west Tuesday Night into
Wednesday. Accumulating snow expected along/west of the Blue
Ridge with several inches possible mountains of SW VA and SE WV.

3). Rainfall potential and QPF amounts increase during the later
half of the week. Flooding likely.

Little to no change in the synoptic pattern expected through the
period. However, a couple of potent southern stream systems
promise to bring copious amounts of precipitation to the area
which is certainly not needed at this time.

The first system of concern comes late Tuesday into Wednesday.
With the 850mb 0C line as far south as the I-40 corridor in NC
during this period, the threat of notable accumulations of
winter precipitation appears likely along/west of the Blue
Ridge. Accumulations of 1-3 inches with higher amounts SE WV
quite possible.

The next strong southern stream system follows right on the
heels of the Tue-Wed system. Temperatures moderate a bit, but
QPF looks to be greater with this system enhancing the threat
for flooding, even to moderate levels. Rainfall of 1 to 3 inches
possible with this event.

Another potent southern stream system with the potential for
even more rainfall expected late in the weekend just beyond the
time frame of this forecast discussion. The flow is amplified
enough with this system that most if not all of the
precipitation should be liquid.

Temperatures will hover mostly in the 40s and 50s for highs
after Wednesday with lows in the 30s and 40s. However, Wednesday
look for highs in the 30s and lows in the 20s west to 40s for
highs and 30s for lows east.

/Confidence Levels in Forecast Parameters/
- Moderate Confidence in Temperatures,
- High Confidence in Precipitation Probabilities,
- Moderate Confidence in Wind Direction and Speed.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
As of 930 PM EST Friday...

VFR conditions expected through 06Z/1AM, then expect lowering
cigs as moisture moves into the region from the west,
transitioning to MVFR by daybreak. Rain/freezing rain
conditions expected for much of the northern Mid-Atlantic
Saturday morning with concerns for icing. High confidence for
freezing rain at LWB and the higher terrain surrounding ROA/LYH.
Actual surface temperature at ROA/LYH may be a few degrees above
freezing, but surrounding ridges will be closer to 30 degrees
with wetbulb readings in the upper 20s, supporting light to
moderate icing. Higher potential for icing is expected along and
north of I-64.


.EXTENDED AVIATION OUTLOOK...

An active weather period is in store for the area next week.
High confidence that several storm systems will impact the
region during the week supporting sub-VFR conditions through
most of the week. There is a high probability for long duration
precipitation episodes, but with high uncertainty as to the
specific type of precipitation, timing and impacts.

&&


.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Flood Watch from 3 AM EST Saturday through Sunday afternoon
     for VAZ019-020.
     Winter Weather Advisory from 3 AM to 1 PM EST Saturday for
     VAZ019-020-024-035-047.
NC...None.
WV...Flood Watch from 3 AM EST Saturday through Sunday afternoon
     for WVZ042>044-507-508.
     Winter Weather Advisory from 3 AM to 1 PM EST Saturday for
     WVZ507-508.

&&

$$

SYNOPSIS...CG
NEAR TERM...PM
SHORT TERM...RAB
LONG TERM...RAB
AVIATION...PM