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-- Discussion containing changed information from previous version are highlighted. --
093
FXUS61 KRNK 230925
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
425 AM EST Sat Feb 23 2019

.SYNOPSIS...
Canadian high pressure to our northeast will combine with upper
low pressure anchored in the south central U.S. to keep
widespread clouds and rain along with cold temperatures in place
across the entire forecast area today. A cold front will move
through the region from the west by Sunday afternoon, finally
bringing an end to the rain, but accompanied by strong and gusty
west winds. High pressure building into the region behind the
front Monday will bring diminishing winds and also provide
mostly sunny conditions along with milder temperatures for the
first part of next week.

&&

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

Another soggy wet day on tap for the area with the continued
threat of mostly minor flooding from non-stop light to
occasionally moderate rain. The pattern remains the same as it
has pretty much for the last several days. A wedge of cool air
east of the Appalachians supported by Canadian high pressure to
our northeast, a mid-level baroclinic zone draped from the TN
Valley across NC/VA, and a deep upper low pressure area in the
southwest blocked by a strong subtropical ridge off the
southeast U.S. coast. A series of upper-level disturbances
continue to track northeast from the parent southwest U.S. upper
low. These factors combine to keep the clouds and rain in place,
and will continue to do so for the next 24-36 hours. Finally on
Sunday, as low pressure develops in the Midwest and moves toward
the Great Lakes, a cold front will move into and through the CWA
bringing an end to the rain.

Again, the main concern for the near term remains that of
flooding. One area of light to moderate rain moved from south to
north through much of the CWA around midnight. Another area is
now moving into the far western part of the CWA and this is
expected to spread east and northeast through the morning and
into the afternoon, keeping steady rain over nearly all of the
forecast area again today, with periods of moderate rain for
sure. In fact, with some enhancement expected of the upper-level
dynamics today as the upper low in the southwest takes on a
negative tilt, the likelihood of periods of heavier rain than
what we have seen during the past 24 hours is likely. We are
already seeing this take place in far eastern TN and western NC
where rainfall rates are approaching 0.50/hour. Thus, WPC has
expanded the moderate risk of excessive rainfall into far
western VA and the slight risk extends eastward now almost to
the eastern border of the CWA, with a marginal risk in all other
areas not covered by the slight. Additional rainfall during the
next 24 hours should be mostly in the 1-2 inch range, but some
amounts between 2-3 inches will be possible in the west, where
the threat of flooding is the greatest. Concerns are
particularly high in the Clinch, Holston, Watauga, and
Greenbrier basins. FFG values are incredibly low, in many parts
of the CWA less than 1.0 inch/3 hours. Rainfall rates during the
night have been mostly in the 0.10 to 0.25 inch/hour range and
there has not been any flooding or river flooding yet of note.
That could well change today. Thus, the Flood Watch will
continue and has been extended slightly in time to accommodate
neighbors and highlight the threat of longer term river flooding
into the day Sunday across the east.

With the wedge locked in across the area today, do not look for
the temperatures to warm much if any at all and will likely hold
steady overnight as well, at least until the cold front arrives.
Temperatures will remain in the 30s to lower 40s at best around
the edge of the wedge today and tonight. Have removed the
mention of ice, however, as temperatures have only fallen into
the upper 30s and at this point mid 30s should be the lowest
point, so feel all areas should remain safely above freezing
averting the threat of any ice this go around.

/Confidence in Forecast Parameters/
Temperatures - High,
Probabilities of Precipitation - High,
Winds - Moderate to High.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
As of 300 AM EST Saturday...

Prefrontal showers will be across the Appalachians and central mid
Atlantic region early Sunday before being swept out by the actual
frontal boundary. The front will move west to east across the area
Sunday morning, then push through Southside and move into the piedmont
early Sunday afternoon. Expect a good burst of strong winds to
accompany the front, with strong gusty winds then persisting across the
entire region through the afternoon as low pressure moving into the
Great Lakes deepens rapidly and enhances the low level wind field.
Winds will taper off east of the Blue Ridge during the evening, but
expect the winds to continue howling west of the Ridge, especially at
the higher elevations, through sunday night as the inversion lowers and
accelerates winds by squeezing the flow. The strong gusty winds will be
problematic since the ground is waterlogged from rainfall and trees may
topple more readily. Expect this will result in downed trees and power
outages being more widespread than is typical during wind events to
include locations east of the Blue Ridge as well. One more surge of
gusty winds is expected Monday morning after diurnal heating breaks the
inversion and mixes winds down to the lower elevations. High pressure
then continues to build over the eastern part of the country with
quiet weather expected into the middle of next week.

The arrival of colder air will lag a bit behind the front on Sunday and
this will allow for temperatures to warm considerably. Expect highs
Sunday to reach the mid 60s to near 70 east of the Blue Ridge with
middle/upper 50s to the west. Highs will be cooler for Monday and
Tuesday though still a bit above normal.

&&

.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
As of 300 AM EST Saturday...

A northern stream cold front will try to join forces with a southern
stream disturbance late Wednesday and bring a chance for rain showers.
At this time, the two do not phase until both systems move off the Mid
Atlantic Coast Wednesday evening. Dry high pressure will briefly keep
the area dry before the next front brings rain to the region Thursday
night into Friday night.

Temperatures will be above normal Wednesday. Clouds and rain will bring
temperatures back to normal Thursday and Friday.
&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
As of 1135 PM EST Friday...

Little change in the weather pattern through the TAF forecast
period across southwest Virginia, northwest North Carolina and
southeast West Virginia, with widespread IFR to LIFR ceilings
and MVFR visibilities. Light to moderate rain along with areas
of fog are expected.

Winds will generally trend toward the east and northeast as weak
lower pressure remains west of the central and southern
Appalachians and a strong wedge covers the mountains and
foothills.

Extended Aviation Discussion...

Cold front is expected to sweep east through the Mid Atlantic
area on Sunday, gradually diminishing/ending the threat for
precipitation with subsequent return to VFR conditions east of
the Blue Ridge during the afternoon.

However, colder upslope winds from the west or northwest
following the front will likely maintain the threat for sub-VFR
weather west of the Blue Ridge through Sunday night, but dry
air will allow VFR conditions to return to all areas Monday,
which should continue into Tuesday before the next frontal
system arrives in the Wed-Thu time frame.

Winds are expected to become strong and gusty behind the front
Sunday afternoon into Monday morning, especially over the
mountains, until high pressure can sufficiently build into the
region later Monday into Tuesday, thereby relaxing the pressure
gradient.

&&

.HYDROLOGY...
As of 1130 PM EST Friday...

Currently have a river flood warning out for Danville through South
Boston along the Dan River and at Randolph on the Roanoke River.
Guidance is suggestion potential minor flooding at Buckingham on
the James.

With where the axis of heaviest QPF is expected, have concerns that
some parts of the Roanoke, New, Greenbrier, Clinch and Holston
Rivers.

Smaller creeks and streams, especially along and west of the Blue
Ridge will likely stay elevated with flooding a good possibility by
Saturday.

Stay tuned for any flood advisories or warnings.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Flood Watch through Sunday morning for VAZ007-009>020.
     High Wind Watch from Sunday morning through Monday morning for
     VAZ007-009>020-022>024.
     Flood Watch through Sunday afternoon for VAZ022>024-032>035-
     043>047-058-059.
     High Wind Watch from Sunday afternoon through Sunday evening
     for VAZ032>035.
NC...Flood Watch through Sunday morning for NCZ001-002-018.
     High Wind Watch from Sunday morning through Monday morning for
     NCZ001-002-018.
     Flood Watch through Sunday afternoon for NCZ003>006-019-020.
     High Wind Watch from Sunday afternoon through Sunday evening
     for NCZ003-019.
WV...Flood Watch through Sunday morning for WVZ042>044-507-508.
     High Wind Watch from Sunday morning through Monday morning for
     WVZ042>044-507-508.

&&

$$
SYNOPSIS...RAB
NEAR TERM...RAB
SHORT TERM...MBS
LONG TERM...MBS/RCS
AVIATION...AMS/WP
HYDROLOGY...RAB