-- Discussion containing changed information from previous version are highlighted. --
705
FXUS61 KRNK 290812
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
412 AM EDT Mon Apr 29 2024

.SYNOPSIS...
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High pressure will result in dry weather and unseasonably warm
temperatures today, then a low pressure system will then push a
cold front through the region on Tuesday, bringing a chance of
showers and thunderstorms. Temperatures will remain above normal
through the middle of the week. Some shower and thunderstorm
potential continues for parts of the area Wednesday, and again
Friday into the weekend.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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As of 400 AM EDT Monday...

Key Message:

  - Unseasonably warm today
  - Slowed down arrival time of precipitation

Overall enough sunshine with scattered mid clouds and
stratocumulus in the afternoon for above normal temperatures
today. Grand Ensemble and Ensemble GFS keep temperatures today
below 90 degrees, with the exception of Buckingham County. But
highs today will still be around the record for this date. See
climate section below.

Cloud cover will increase from the west late tonight. Have
slowed down the onset time of rain and lowered the probability
of precipitation.
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&&

.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
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As of 200 AM EDT Monday...

Key Points:

1. Above normal temperatures
2. Showers and some storms on Tuesday
3. Lingering isolated showers on Wednesday
4. Dry for Thursday

A look at the 28 April 00Z NCEP Ensemble Mean 500 mb Geopotential
heights shows a shortwave trough crossing the area on Tuesday.
Wednesday into Thursday this wave heads east into the Atlantic while
an upper level ridge is centered over our region. At the surface,
Tuesday into Tuesday night, a cold front crosses our region. On
Wednesday, the front is slow to exit eastern sections of the area,
all the while high pressure builds over the Plains States. On
Thursday, the front moves into the Western Atlantic while a ridge
builds over the Lower Ohio Valley.

Output from the 28 Apr 12Z Ensemble Situational Awareness Table
shows 850mb temperatures around +12C over the area Tuesday and
Wednesday. By Thursday, those numbers are slightly higher around
+14C to +16C, which touches the low end of the 90 to 97.5 percentile
of the thirty-year climatology. Precipitable Water values on Tuesday
will average 1.00 to 1.25 inches Tuesday, around or a little
over 0.75 inch on Wednesday and Thursday.

The above scenario places Tuesday with the best chance of showers
and perhaps a few storms, lingering into Tuesday night. On
Wednesday, with the front still near the area, mainly eastern parts
of the region. Return of high pressure on Thursday should mean a
return to dry weather for the area. Temperatures will be above
normal for this time of year with Thursday likely the warmest of the
three days.

Confidence in the above weather scenario is moderate to high.
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&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
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As of 140 AM EDT Monday...

Key Points:

1. Slightly cooler temperatures but still a bit above normal
2. Chance of showers and storms each day with Saturday having the
greatest probability.

A look at the 28 April 00Z NCEP Ensemble Mean 500 mb Geopotential
heights shows the axis of an upper level ridge shifting east of the
region in response to a strong trough moving through the Northern
and Central Plains states. Saturday the axis of the upper trough
moves closer to our region, and then crosses the Appalachians on
Sunday. At the surface, low pressure and its associated cold front
cross the Great Lakes region on Friday. By Saturday, the front is
over our region. On Sunday, the Saturday system will be east of the
region with weak ridging over the area. Another low pressure center
is expected to be moving across Ontario/Quebec. The axis of this
low/trough will be approaching the area from the west.

Output from the 28 Apr 12Z Ensemble Situational Awareness Table
shows 850mb temperatures are expected to range from +12 to +13C
across the area Friday through Sunday. Precipitable Water values on
Friday will average a little over 1.00 inch Friday, around 1.00 to
1.25 inches Saturday and around 1.00 inch Sunday.

The above scenario offers increasing chance of showers/storms on
Friday from west to east as the ridge shifts east and a central US
trough heads east. There should be good coverage of showers and
storms Saturday as the front crosses. On Sunday, while the cold
front is expected to be to our east, the passage of the upper trough
and its steeper lapse rates aloft and daytime heating should continue
the chance of showers on Sunday. Temperatures will be a little
cooler as compared to mid-week, but still slightly on the mild side
of normal.

Confidence in this portion of the forecast is on the low side of
moderate.
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&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
As of 155 AM EDT Monday...

VFR conditions expected for most sites through the period.

Already noting fog was forming along the New River as seen in
the Night Fog satellite images. Fog may also develop after 08Z
along the Greenbrier River. The most likely time frame for
MVFR to potentially IFR fog at KLWB and KBCB is from 08Z/4AM to
13Z/9AM.

Few-sct diurnal stratocumulus will develop by early afternoon
with bases 3-5 kft.

Expecting a southwest wind once the inversion breaks this
morning. A few gusts up to 20 knots are possible this afternoon,
but occurrence will be limited.


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


Extended Aviation Outlook...

NW winds arrive behind a cold front crossing the area Tuesday
with TSRA and MVFR or lower ceilings. Widely scattered SHRA/TSRA
will be possible again on Wednesday as the front exits the
area.

Thursday is forecast to be VFR and dry.

The next cold front and probability of precipitation arrive in
the area on Friday. This brings the potential for showers and
thunderstorms with MVFR ceilings and visibilities.

&&

.CLIMATE...
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As of 400 AM EDT Monday...

Record highs for April 29



Bluefield, WV....86 in 2017   Forecast high 80
Danville, VA.....91 in 1981   Forecast high 87
Lynchburg, VA....88 in 1974   Forecast high 88
Roanoke, VA......89 in 1944   Forecast high 89
Blacksburg, VA...86 in 2017   Forecast high 83
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&&

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

&&

$$

SYNOPSIS...AMS
NEAR TERM...AB/RCS
SHORT TERM...AS
LONG TERM...AS
AVIATION...AMS/RCS
CLIMATE...AMS