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000
FXUS61 KRNK 271313
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
913 AM EDT Sat Apr 27 2024

.SYNOPSIS...
A ridge of high pressure will cover the region through Monday
with a mix of sun and clouds expected today transitioning to
mostly sunny skies Sunday and Monday, allowing for much warmer
temperatures. Rain chances return by Tuesday with a frontal
passage and additional scattered showers and thunderstorms will
be possible, mainly in the afternoon hours,for the remainder of
the work week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 911 AM EDT Saturday...

Key Message:

1. Increased high temperatures today.

The 12Z RNK sounding revealed a healthy inversion around 800mb
with a very shallow layer of east/southeast winds which will
keep some clouds along the east facing slopes of the Blue Ridge
through the rest of the morning. As low level winds back to the
south later today, these upslope clouds will erode.

Breaks in the overcast cloud cover east of the Blue Ridge are
also expected by afternoon, and with surging 1000-850mb
thicknesses in the wake of a passing warm front earlier this
morning, and a building upper level ridge, bumped up high
temperatures a few degrees.

Mainly dry conditions are expected, but a weak shortwave over KY
this morning will move over the building upper level ridge and
may spawn some widely scattered showers north of I-64 late this
afternoon.

Tonight, high pressure builds over the area, but southerly winds
and positive vorticity advection aloft will keep clouds around
for most of the overnight. Lows should be in the 50s.

Confidence is moderate in the near term forecast, with the
greatest uncertainty in the temperatures forecast as the NBM
ensembles show a larger than average spread for highs today.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
As of 115 AM EDT Saturday...

Key Points:

1. Dry Sunday and Monday and trending warmer.
2. Showers and some storms possible Tuesday/Tuesday night
3. Slightly cooler Tuesday but still above normal

A look at the 26 April 12Z NCEP Ensemble Mean 500 mb
Geopotential heights shows a ridge over the eastern US on
Sunday. A shortwave trough over the upper Mississippi Valley is
expected to head eastward and move through the crest of ridge,
over our region, by Tuesday. At the surface, on Sunday, a ridge
of high pressure will extend from the coast of the Carolinas
northeast to the Canadian Maritimes while low pressure will be
centered over the Central Plains states. This same low is
expected to move into the Great Lakes region on Monday, and by
Tuesday be over Ontario with a cold front moving towards and
then across our area.

Output from the 26 Apr 12Z Ensemble Situational Awareness Table
shows 850mb temperatures trending milder Sunday through Tuesday.
Values on Monday may touch +14C to +16C, which would be within
the 90 to 99 percentile of the thirty year climatology. On
Tuesday, numbers decrease a bit from the Monday values, but will
still be on the warm side of normal. Precipitable Water values
hover around the 1.00 inch mark Sunday into Monday. By Tuesday,
values increase to closer to 1.25 inches for eastern parts of
the region.

The above reflects a dry forecast still for Sunday into Monday,
but with increasing temperatures. On Tuesday, precipitation
chances increase from west to east with the passage of the
shortwave trough. Forecast lifted indices and CAPE values
suggest enough instability for mention of thunderstorms along
with the showers.

Confidence in the above weather scenario is moderate to high.

&&

.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
As of 1245 AM EDT Saturday...

Key Points:

1. Daily chances of isolated to scattered afternoon/evening
showers/storms
2. Friday will have the greatest coverage
3. Temperatures above normal through the period


A look at the 26 April 12Z NCEP Ensemble Mean 500 mb
Geopotential heights shows flow aloft trending to zonal by
Thursday after the departure of a shortwave trough on Wednesday.
By Friday, another trough within the mean westerly flow is
expected to cross our area. At the surface, on Wednesday, a weak
trough will still be over eastern portions of the area, on the
north side of high pressure centered east of the coast of the
Carolinas. Low pressure and associated cold front will bisect
the center of the country. Thursday into Friday, the Central US
low/cold front will make progress eastward, crossing, or simply
reaching, our region early Friday.

Output from the 26 Apr 12Z Ensemble Situational Awareness Table
shows 850mb temperatures on the warm side of normal through the
period. A few spots may reach numbers within the 90 to 97.5
percentile range of the thirty-year climatology. Precipitable water
values on Wednesday are down a bit from values on Tuesday with 0.75
to 1.00 inch common across the area. These values hold fast through
Thursday, but increase to closer to 1.00 to 1.25 inches by Friday.

The above reflects a forecast with frequent bouts of showers and
storms from increasing moisture in advance of an approaching trough.
Of the three days, Wednesday may be the least active with Friday
the most active. Temperatures will be on the warm side of normal.

Confidence in the above weather scenario is moderate.

&&

.AVIATION /13Z SATURDAY THROUGH WEDNESDAY/...
As of 230 AM EDT Saturday...

A warm front was nearing this morning and some light showers
were beginning to develop, mainly over the western NC mountains
and the Alleghany Highlands. The chance for -SHRA or at least
VCSH increases for most of the TAF sites from now until about
13-15Z, after which ceilings improve as the front moves away.
It appears that LIFR/MVFR ceilings will a feature this morning
before this occurs.

Winds will shift more southerly by 15Z, helping low clouds to
scatter and lift, making for generally BKN to OVC, mostly VFR
ceilings through the remainder of the day. Winds may be gusty to
about 20 kts this afternoon. Overnight into Sunday morning
expect mostly mid and high clouds and light winds.

Extended Aviation Outlook...

Sunday and Monday should be mainly VFR. Winds turn more
southerly Sunday and westerly Monday through Tuesday morning. NW
winds will accompany a cold front crossing the area with -TSRA
areawide and MVFR or lower ceilings. Widely scattered -SHRA/-TSRA
will be possible again Wednesday afternoon.

&&

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

&&

$$

SYNOPSIS...BMG/NF/SH
NEAR TERM...PH/SH
SHORT TERM...DS
LONG TERM...DS
AVIATION...SH