289
FXUS61 KRNK 200605
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
205 AM EDT Mon May 20 2024

.SYNOPSIS...
High pressure will keep our area mostly dry through Wednesday.
Showers and a few thunderstorms return Thursday and linger into
the weekend as a frontal boundary stalls over the area.
Temperatures will be near or a few degrees above normal for
much of the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 200 AM EDT Monday...

Key Messages:

1) Dry and warm, with clouds early.

An area of clouds was noted on satellite this morning, generally
from Warm Springs and Lynchburg, then southwest towards Boone.
Just inland from VA Beach, an area of stratus was slowly making
progress westward towards our southern Piedmont, but still
looks a couple hours away. In between these areas of clouds,
fog had developed. Drier air had allowed parts of the mountains
to drop into the 50s so far this morning, with Burke`s Garden in
the 40s.

A trough of low pressure was oriented over the Mid Atlantic and
into GA/Carolinas, with positively tilted high pressure from
the Gulf Coast towards NY State. An area of negative vorticity
will be steered over our area from the northeast today, on the
eastern side of the ridge. This will help squash precipitation
chances and decrease any lingering cloud cover after mid
morning. PWATs remain below an inch, and this combined with
highs in the 70s to low 80s and sunshine will make for a
pleasant day. The only chance for an isolated shower would be
over the far southern Blue Ridge this afternoon.

Tonight, winds become light and variable as high pressure
retreats east. Expect another shot of stratus migrating from
the coast Monday morning, possibly reaching the southern
Piedmont.

Confidence in the near term is high.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
As of 1245 AM EDT Monday...

Key Points:

1. Well above normal temperatures.
2. Mainly dry Tuesday through Wednesday.
3. Showers and storms increase west to east across the region on
Thursday.

A look at the 19 May 00Z NCEP Ensemble Mean 500 mb Geopotential
heights shows the region will be within a pattern of general sw-
ne flow with a shortwave trough passing north of the area on
Thursday into Thursday night. Concurrently, a ridge of high
pressure will build over the SE US. At the surface, on Tuesday,
low pressure is expected to be centered over the Upper
Mississippi River Valley, with high pressure centered just off
the mid-Atlantic coast. By Wednesday, the center of the high is
displaced eastward by the advance of the low to near the
Ontario/Quebec border. An associated cold front is expected to
extend southwest into Lower Ohio/Mid Mississippi Valley. By
Thursday, the low is over western Quebec with the associated
cold front over or just east of our area by Thursday evening.

Output from the 19 May 12Z Ensemble Situational Awareness Table
shows 850mb temperatures climbing slowly Tuesday through
Wednesday night. Values will average +16C across the area by
Wednesday, which is within the range of the 90 to 97.5
percentile of the 30-year climatology for much of the area, and
the 97.5 to 99 percentile for portions of the area near the
WV/VA border. On Thursday, values dip a degree or two during the
day, and by late Thursday night range from roughly +12C to +14C
across the area. Precipitable Water values on Tuesday will
average 0.75 to 1.00 inch across the area on Tuesday. These
values will be on the increase through Thursday, averaging
around 1.25 inches by the mid-afternoon on Thursday. This values
just touches the low end of the 90 to 97.5 percentile of the
30-year climatology for this time of year. By late Thursday
night, values will range from 0.75 to 1.25 inches across the
area, with the high end of this range across the southeast
portion of the region.

The above pattern suggests a period of well above normal
temperatures with limited, if any, precipitation chances Tuesday
and Wednesday. However, as the cold front approaches, and then
crosses our area on Thursday, first look for the arrival of
scattered showers over southeast West Virginia late Wednesday
night. During the day Thursday, look for showers and storms to
increasing in coverage from west to east as the day progresses,
with the best chances of storms during the afternoon and evening
hours. Coverage will slowly decrease through the night.

Confidence in the above weather scenario is moderate to high.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
As of 1245 AM EDT Monday...

Key Points:

1. Above normal temperatures.
2. Daily chances of mainly mid-afternoon through early evening
showers and storms.

A look at the 19 May 00Z NCEP Ensemble Mean 500 mb Geopotential
heights shows the region remaining a general sw-ne flow aloft,
but will gradually increasing heights each day. The latitude of
passing shortwave troughs on the north side of the prevailing
flow are expected to trend farther north. One such feature is
expected to cross north of the region Saturday into Sunday. At
the surface, for Friday through Sunday, the pattern transitions
into one with a persistent low/trough over central CONUS and
high pressure/ridge over over the Atlantic Ocean. This places
our region within a generally southerly flow pattern with
trajectory origins from either off the eastern Gulf of Mexico or
coasts of SC/GA.

Output from the 19 May 12Z Ensemble Situational Awareness Table
shows 850mb temperatures averaging around +14C across the area
Friday and Saturday, and inch closer to a +16C average by
Sunday. Precipitable Water values during this portion of the
forecast will average 1.00 to 1.25 inches.

The above pattern suggest our region Friday through the weekend
will be within a very mild and humid airmass. This pattern may
allow for daily chance of showers and storms. First on Friday,
the front that crossed the area on Thursday, may pivot north
thanks to increasing southerly flow, and be the focus for
showers and storms. Saturday into Sunday, we will remain in a
potentially unstable airmass with residual outflow boundaries
from the previous day`s convective activity being potential
initiation locations for that day`s convective activity.

Confidence in the above weather scenario is moderate to high
regarding the general synoptic pattern and above normal
temperatures. However, confidence is low regarding the
specific locations of the forecast area that will have the
greatest chances of showers and storms each day, and the
specific timing of that activity. Although, mid-afternoon
through early evening would be the most likely range of times.

&&

.AVIATION /05Z MONDAY THROUGH FRIDAY/...
As of 200 AM EDT Monday...

Areas of IFR/LIFR/MVFR fog and stratus will continue to develop
this morning before improving to VFR after 13-14Z. Some VFR
afternoon cloudiness possible this afternoon, especially over
the ridges. Late tonight into Tuesday morning, fog may be a
little harder to come by. An area of stratus, again making its
way from coastal VA similar to this morning, may impact LYH and
DAN.

Otherwise VFR Tuesday.

EXTENDED AVIATION OUTLOOK...

VFR conditions persist into Wednesday, and possibly for parts of
the area the first half of Thursday. However, chances for
SHRA/TSRA increase beginning Thursday and continuing into the
weekend, as a front stalls across the area. This will bring
increasing periods of IFR/LIFR/MVFR conditions.

Winds will become more southerly Tuesday, then become more
west/SW Wednesday through Friday.

&&

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

&&

$$

SYNOPSIS...SH
NEAR TERM...SH
SHORT TERM...DS
LONG TERM...DS
AVIATION...SH