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000
FXUS61 KRNK 060744
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
344 AM EDT Thu May 6 2021

.SYNOPSIS...
High pressure will pass overhead today providing dry but
seasonally cool weather. Clouds will be on the increase tonight
ahead of the next cold front which will arrive Friday morning,
associated with showers and even cooler temperatures. Another
brief period of drying will take place Saturday as high pressure
passes across the region, but then transition to a wet close for
the weekend as unsettled weather returns Sunday and Monday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 330 AM EDT Thursday...

Today will be a good drying day.

High pressure will settle overhead today promoting dry
conditions...dewpoints in the 20s/30s yielding RH values under
30 percent for this afternoon. Aside for some morning cloudiness
across the mountains, the overall expectation is for mostly
sunny skies. There is a northerly breeze this morning, but
expect this to become light and variable this afternoon, so
inspite of the cooler than normal temperatures, it will most
likely feel quite pleasant to be outdoors this afternoon, the
high sun angle for May countering the slightly cooler than
normal temperature profile.

Clouds will be on the increase this evening and into the
overnight ahead of the next storm system. An upper level trough
mid-CONUS will move rapidly east, the associated surface cold
front approaching our forecast area toward daybreak Friday. Attm
it appears any threat for precipitation will hold off until
after midnight tonight, showers overspreading the mountains from
the west during the late night.

Temperatures today and tonight will run about 5 degrees cooler
than normal.

Confidence in the near term is high.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
As of 330 AM EDT Thursday...

...Unsettled Weather Conditions through Much of the Period with
Well Below Normal Temperatures...

A deepening upper trough will evolve through the period. Almost
a winter like pattern with 850mb temperatures dropping toward 0C
along the northern border during the time frame. This deepening
will largely take place Friday as a strong short wave tracks
from the Great Lakes through the base of the upper trough
anchored right over the RNK CWA. Given that the bulk of the
associated dynamics arrives during max heating combined with
cold advection aloft, would expect a rather active afternoon
Friday with showers and scattered thunderstorms. However, the
degree and intensity of thunderstorms should be limited by the
increasingly cool surface temperatures. In addition, with the
cold air aloft, cloud cover will likely thicken early in the day
which will limit surface insolation. CAPE and instability is
limited mainly to areas east of the Blue Ridge and timing of the
short wave may be such that the most robust activity takes place
largely across the eastern part of the CWA Friday afternoon and
toward the coastal plain. It does not look overly impressive
with regard to intensity for our region, but some cells could
produce small hail given the increasingly cold air aloft and
lowering freezing level.

Saturday looks to be somewhat quieter, but still with an
abundance of clouds and below normal temperatures. Precipitation
Saturday should be little to none and what there is should be
confined to areas mainly along/west of the I-77 corridor.

Sunday, as the upper flow temporarily becomes more zonal in
response to the upper trough quickly lifting out to the north, a
warm front is projected to lift through the region. Showers and
possibly a thunderstorm could be triggered along this boundary.
This activity would be largely confined to western and northern
areas during the afternoon/evening. Overnight Sunday into
Monday morning, another short wave and associated frontal
boundary approach from the west with a better chance of more
widespread showers and thunderstorms impacting much of the
region. It should be noted that some periods of gusty winds are
possible, especially Saturday behind the Friday short wave.

As noted above, temperatures are expected to be well below
normal through the period. Maximum temperatures are expected to
average in the 50s west to 60s east through the weekend with
lows in the 30s west and 40s east. These readings are roughly
7-10 degrees below normal for this time of year. At this point,
cloud cover, wind, and precipitation should prevent much if any
frost/freeze concerns, but some of the usual spots like Burkes
Garden may need to be monitored for frost/freeze at times
through early next week.

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

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 330 AM EDT Thursday...

...Unsettled Weather Conditions with Below Normal Temperatures
Continue...

As noted in the Short Term Discussion...active weather conditions
along with below normal temperatures are expected to continue
right into next week. Upper heights will remain suppressed
across much of the central/eastern U.S. through the period with
an active southern stream anchored near 35 degrees latitude.
This will keep a series of vigorous short waves in the southern
stream progressing eastward across the mid-latitudes/southern
half of the U.S. while the suppressed upper heights and
associated colder than normal temperatures aloft keep surface
temperatures below normal.

Monday in particular looks to be quite active as a strong short
wave tracks from the southern plains toward the southeast and
southern Mid-Atlantic region. Instability will peak Monday
afternoon as this system moves through the region and 850mb
temperatures briefly surge toward +12C after being closer to 0C
through the weekend. At this point, the threat of severe weather
and heavy rainfall with this system should remain to our south
mainly across the southeast states as the northern stream acts
to suppress the strongest dynamics across that region.

Tuesday and Wednesday should be a bit quieter, but still
somewhat unsettled as yet another short wave tracks from the
south central U.S. into the southeast U.S. Any deviation of the
main storm track a bit further north puts our region right in
the main track of this and subsequent systems through the end of
the week. So expect lots of clouds and chances for precipitation
most days, although the main threat should be Monday here, and
remaining more south of our region Tuesday-Wednesday.

Temperatures will warm close to normal levels Monday before
showers/thunderstorms arrive, then return to 5-8 degrees below
normal once again for the remainder of the period. Look for
highs in the 60s and 70s Monday cooling back to mostly 60s Tue-
Wed. Lows will be in the 40s through most of the period, except
mainly 50s on Monday.

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

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
As of 300 AM EDT Thursday...

Lingering low level cloud cover over the mountains will
dissipate this morning yielding to widespread VFR for today
and tonight. There is some valley fog across eastern KY and
into far western VA, this fog expected to dissipate after
sunrise.

As for wind, expect a light northerly wind this morning,
becoming light and variable for the afternoon as High
Pressure settles overhead.

Upper level moisture will be on the increase this evening and
overnight, ahead of the next storm system which will be
approaching from the west. Showers and the potential for Sub-
VFR will return by the morning push Friday.

Moderate to high confidence in visibility, wind, and ceilings
through the 24 hour TAF period.

Extended Aviation Discussion...

Expect showers and sub-VFR Friday...VFR again Saturday followed
by another round of sub-VFR conditions late Sunday into Monday.

&&

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

&&

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