795
FXUS61 KRNK 021034
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
634 AM EDT Thu May 2 2024

.SYNOPSIS...
Today and tonight high pressure will result in dry weather and
above normal temperatures. A low pressure system brings wet
weather to the region by the weekend along with cooler
temperatures. Unseasonably warm temperatures and a daily threat
of late day showers and thunderstorms return for Monday through
Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 245 AM EDT Thursday...

Key message:

 - Unseasonably warm today
 - Fog in the piedmont this morning

Region remains under a 500 MB ridge today and tonight. Little
variation in the synoptic pattern between models. No change in
airmass today with 850 MB temperatures in the +14 to +18 range by
the end of the day. Expect high temperatures in most locations to be
10 to 20 degrees above normal.

Nighttime fog satellite images were showing the formation of fog in
central and eastern Virginia, and along the New and Greenbrier River
Valleys. Similar to Wednesday, any fog will dissipate by mid
morning.

Mid and high clouds spread into the area tonight. NBM lows are
reasonable.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
As of 125 AM EDT Thursday...

Key Points:

1. Above normal temperatures with Friday the warmest day.
2. Chance of showers and storms each day with Saturday having the
highest probability.
3. Locally heavy rain is possible Saturday and Saturday evening.

A look at the 1 May 00Z NCEP Ensemble Mean 500 mb Geopotential
heights shows on Friday a N-S oriented upper ridge centered from
western NY south into eastern NC. An eastward moving closed low
will progress from Manitoba to Ontario. On Saturday, the ridge
shifts a bit farther east while a negatively tilted shortwave trough
moves through the Great Lakes region. There is a hint of a weak
shortwave trough moving across GA/FL. On Sunday, the Great Lakes
trough is a bit less amplified and extends south from Ontario into
the mid-Atlantic states. The GA/FL shortwave trough will be closer
to the SC/GA border. At the surface, on Friday a ridge of high
pressure will extend N-S just off the East Coast of the US. Low
pressure will be over southwest Ontario with a general area of
troughiness extending southeast into the Ohio and Tennessee Valleys.
This pattern changes very little on Saturday. By Sunday, the ridge
is expected to have shifted a bit more east while the trough shifts
east to over our region.

Output from the 1 May 12Z Ensemble Situational Awareness Table shows
850mb temperatures lower than those expected today, but still above
normal for this time of the year for Friday. Additionally, at values
of +13C to +14C they touch the low end of the 90 to 97.5 percentile
of the thirty-year percentile of climatology. On Saturday and
Sunday, values are only slightly cooler at +12C to +13C.
Precipitable Water values on Friday are expected to range from 1.00
to 1.25 inches, with the upper portion of this range touching the 90
to 97.5 percentile of the thirty-year climatology. On Saturday,
these numbers increase to 1.25 to 1.50 inches, or with the 90 to 99
percentile of the thirty-year climatology. By Sunday, values are
expected to decrease slightly to 1.00 to 1.25 inch.

The above weather scenario continues to offer the region with a
forecast that has well above normal temperatures for this time of
the year, with Friday being the warmest of the three days.
Precipitation chances look to increase through Saturday thanks to
both improving onshore moisture flux within the clockwise flow of
the exiting ridge, and increased dynamics aloft with the approach of
the upper trough and approach and passage of the surface front. The
concern exists Saturday into Saturday evening for locally heavy
rain. While we are not expecting a widespread heavy rain evening,
the training of excessive moisture laden showers and storms could
result in localized rainfall amounts over one inch in a short period
of time. Sunday is a bit of a question mark. Much will depend upon
how much progress the front makes after Saturday and whether a
shortwave trough moving through the Deep South interacts with the
front. Our forecast has been banking on the front lingering over or
near the region, helping to maintain a focus for additional activity
on Sunday. At this time, we see not reason to deviate notably from
that solution.

Confidence in the above weather pattern is moderate.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
As of 100 AM EDT Thursday...

Key Points:

1. Trending warmer each day with Wednesday potentially the warmest.
2. Chance of showers/storms each day, especially northwestern sections,
with Monday seeing the best coverage.

A look at the 1 May 00Z NCEP Ensemble Mean 500 mb Geopotential
heights shows zonal flow across our area with a shortwave trough
moving through the Canadian Maritimes on Monday. An amplified trough
is expected to dig even more across the the Pacific Northwest and
the Rockies. Thanks to the deepening trough, ridging is expected to
develop from the mid-Mississippi Valley north into southern
Manitoba. On Tuesday, the axis of the ridge shift east to over our
region, while a broad trough covers much of western CONUS. By
Wednesday, perhaps due to ensemble averaging, both the trough and
the ridge lose a lot of their definition with a lengthly path of sw-
ne flow from the Four Corners region through the mid-Mississippi
Valley to across our region and into the Western Atlantic. At the
surface, on Monday, low pressure deepens over the Dakotas with a
cold front extending south into Texas. A shortwave trough will be
heading northeast through New England and the Canadian Maritimes. On
Tuesday, the low over the Dakotas makes limited progression
eastward. Southwest flow develops over area between this low and an
area of high pressure in the Western Atlantic off the GA/FL coast. On
Wednesday, the main low makes some progress eastward to over the
Upper Mississippi Valley. There are hints a shortwave trough may
ride northeast over our region within the southwest flow.

Output from the 1 May 12Z Ensemble Situational Awareness Table shows
850mb temperatures for Monday of +12C to +14C, around +16C on
Tuesday, or within the 90 to 97.5 percent of the thirty-year
climatology.  For Wednesday, we could be looking temps around +18C,
or numbers that would be the very warmest among the thirty-year
climatology for this time of the year. Precipitable Water values on
Monday are expected to average 1.00 to 1.25 inches. These values
increase to around 1.25 inches on Tuesday, which touches the 90 to
97.5 percentile of the thirty-year climatology, and for Wednesday,
values are down slightly to the 1.00 to 1.25 range.

The above weather scenario offers the region a three day period with
gradually increasing temperatures. Values on Wednesday have the
potential of being the warmest of the three. As we transition into a
southwest flow pattern with the main low over the Northern Plains
states, we will have the potential for shortwave troughs within this
flow regime to pass over or just north of the area. Each day of the
forecast will have a chance of showers or storms for a portion of
the region, with the northwestern sections being the favored
location because of the aforementioned pattern. Monday has the
potential of for having greatest potential for showers/storms for a
greater expanse of the area as the Saturday/Sunday cold front lifts
back north as a warm front.

Confidence in the above weather pattern is moderate.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
As of 630 AM EDT Thursday...

Satellite Fog images showed fog in central and eastern
Virginia, and in the river valleys west of the Blue Ridge.
Bufkit forecast sounding suggest the western edge of the more
extensive fog this morning will be somewhere between KFVX and
KDAN/KLYH. The fog will dissipate by 14Z/10AM.

VFR conditions are expected for the rest of the TAF forecast
period.

Once mixing begins today winds will be mainly from the
southeast to south with speeds less than 10 kts.

Above average confidence for ceiling and wind.
Average confidence for the extent of fog this morning.


Extended Aviation Outlook...

Thursday night and the first half of Friday look VFR with dry
weather.

A front with showers and TSRA to the region, possibly as early
as Friday afternoon in the west. The arrival timing could
be slowed down however.

The increased chances for rain spreads to the remainder of the
region by Saturday along with more extensive MVFR or lower ceilings.

Chances for rain/TSRA/MVFR or lower conditions continue Sunday
through Monday, mainly in the afternoon hours each day.

&&

.CLIMATE...
As of 200 PM EDT Wednesday...

Record high temperatures for May 2

Bluefield, WV....89 in 2010
Danville, VA.....93 in 1942
Lynchburg, VA....91 in 1942
Roanoke, VA......92 in 1959
Blacksburg, VA...87 in 1942

&&

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

&&

$$

SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...DS
LONG TERM...DS
AVIATION...AMS/BMG
CLIMATE...AMS