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000
FXUS61 KRNK 131746
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
146 PM EDT Sat Apr 13 2024

.SYNOPSIS...
High pressure will cover the region tonight leading to lighter
wind. A low pressure system will track across the Great Lakes Sunday
through Thursday, pushing a front into the Mid Atlantic states,
along with a low chance of showers and thunderstorms. Temperatures
will be above normal next week, until a stronger low pressure system
and cold front cross the region on Thursday and Friday.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 130 PM EDT Saturday...

Key message:

 -  Wind Advisory Remains effect into this evening

Long wave through axis was east of the region Saturday morning.
Mountain wave cirrus had dissipated by mid morning. Low level jet
starts to diminish around 21Z/5PM. At the surface wind speeds
diminish in the late afternoon then drop off more rapidly after
sunset. More breezy weather is expected on Sunday once mixing
begins. Surface high pressure will cross the region on Sunday. 3kn
NAM and WRF guidance develop isolated showers and thunderstorms
Sunday afternoon.


&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 130 PM EDT Saturday...

Key message:

  - Chance of showers and thunderstorms Sunday night and Monday
  - Above normal temperatures

Short wave comes through the northwest upper flow Sunday night, then
pattern returns to upper ridging through Tuesday. Some deeper
moisture and low level convergence along a cold front that drops
south into the area Sunday night amd Monday. the front stalls along
the Virginia/North Carolina border on Monday night, then lifts north
through the Ohio Valley on Tuesday.

Models showed some instability along the boundary on Monday and in
the warm sector on Tuesday. Enough to include a slight chance of
thunderstorms in the Monday afternoon and evening forecast but lack
of synoptic scale forcing will limit coverage of showers and
thunderstorms.

NAEFS indicated that the air mass in the warm sector Monday and
Tuesday was above normal. Will be leaning toward warmer guidance for
highs in this time range.

&&

.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
As of 1240 PM EDT Saturday...

Key Points:

1. Warm with isolated to scattered shower Wednesday and Thursday.
2. A little cooler Friday with greater coverage of showers and
storms.
3. Cooler Saturday with lingering showers in parts of West Virginia.

A look at the 13 April 00Z NCEP Ensemble Mean 500 mb Geopotential
heights shows the following scenario Wednesday through Saturday. On
Wednesday, a shortwave ridge is expected to be centered over New
England and extend south to off the coast of the Carolinas. A
shortwave trough, in advance of a more robust trough, is expected
to be heading northeast across the Great Lakes and Ohio Valley
regions. By thursday morning, this first weaker shortwave is
expected to be overtaken and absorbed into the flow around the
second, more robust trough. This more robust trough will be centered
over the Upper Mississippi Vally by Thursday evening. By Friday
evening, this trough axis is expected to extend south from western
Quebec to over the Appalachians. By Saturday evening, the axis will
have shifted east to over New England, placing our region within a
northwest flow pattern. As the surface on Wednesday, low pressure is
expected to be centered near MN/MI with an associated warm front
heading southeast over the mid-Atlantic region and a cold front
southwest into MO/AR. By Thursday, the warm front will have moved
farther north towards New England, The system`s cold front will
extend south into the Lower Ohio Valley, and a prefrontal trough is
expected to develop across the lee of the Appalachians. On Friday,
the cold front is expected to cross our area and be over eastern
VA/NC by the evening. By Saturday, the front will be off the coast,
placing us within a northwest flow between the departing front and a
building high across central CONUS.

Output from the 13 Apr 00Z Ensemble Situational Awareness Table
shows 850mb temperatures on Wednesday around +12C to +13C, or values
within the 90 to 97.5 percentile of the 30 year climatology. On
Thursday, values are expected to be only slightly lower than these.
Come Friday, there will be trend of decreasing values through the
day, reaching roughly +4C to +8C by Friday evening. On Saturday,
values continue their downward trend to a range of roughly 0C to +4C
by the early evening. Precipitable Water values on Wednesday are
expected to average around 1.00 inch across the area. This will be
on the high side of normal. These values fall only slightly on
Thursday to 0.75 to 1.00 inch. Friday the value is down to an
average of 0.75. On Saturday values decrease to an average of 0.50
inch.

The above weather scenario points to the following expected
forecast. The warm front on Wednesday looks to be too far north by
the early part of the day to be a weather maker for the region.
However, the shortwave trough heading across the Great Lakes and
Ohio Valley will bring showers isolated to scattered showers, and
possibly a few thunderstorms, to mainly the mountains. The best
coverage is expected to coincide with peak heating of the day but
continue into the evening hours.

On Thursday, most of the region should have a break from the
precipitation as a brief period of shortwave ridging moves across the
area in between the two trough systems. The second system however
looks on track to bring isolated to scattered showers to the far
western portions of the area by daybreak Friday.

During the day Friday, a cold front will gradually cross our area.
Coverage of showers and storms will be greatest across central and
eastern parts of the region. Peak heating of the day will coincide
with the expected frontal position.

For Saturday most of the region is expected to be dry thanks to
gusty northwest winds. The one exception will be the preferred
upslope areas of Southeast West Virginia. Within this region,
expect cloud cover and isolated showers to linger into Saturday.

Temperatures during the period will be above normal Wednesday and
Thursday, closer to normal on Friday, and a little below normal for
Saturday.

Confidence in the above weather scenario is moderate.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
As of 140 PM EDT Saturday


VFR conditions expected through the TAF forecast period.

Long wave through axis was east of the region Saturday morning.
Mountain wave cirrus had dissipated by mid morning.

Low level jet starts to diminish around 21Z/5PM. At the surface
wind speeds diminish in the late afternoon then drop off more
rapidly after sunset.

More breezy weather is expected on Sunday around 14Z once
mixing begins. Wind gusts in the 20 to 30 kt range are expected
through 18Z/2PM Sunday.

3km NAM and WRF guidance develop isolated showers and thunderstorms
Sunday afternoon. Coverage and probability of precipitation was
too low to include in the local TAFS at this time.

Forecast confidence is average.

OUTLOOK...

Monday, a weak cold front may bring a return of some showers
and patchy sub-VFR conditions to southeast West Virginia.
Elsewhere, VFR conditions are expected.

Mainly VFR through Tuesday with a few showers/storms possible
north of KLWB.

A low pressure system and stronger cold front approach the area
Wednesday and Thursday. Scattered showers and thunderstorms,
with associated MVFR flight conditions, are expected ahead of
this system, especially Wednesday in the mountains.

Confidence in the above extended aviation scenario is good.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Wind Advisory until 6 PM EDT this evening for VAZ009-012>020-
     022>024-032>035.
NC...Wind Advisory until 6 PM EDT this evening for NCZ001>003-018-
     019.
WV...Wind Advisory until 6 PM EDT this evening for WVZ508.

&&

$$

SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...AMS
LONG TERM...DS
AVIATION...AMS/PM