-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 150155
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
955 PM EDT Sun Apr 14 2024

.SYNOPSIS...
A low pressure system will track across the Great Lakes tonight
through Thursday, pushing a front to near the I-64 corridor by
Monday afternoon. Scattered thunderstorms are expected to
develop along the front, a few which could be strong, and then
drift southward along with the front to near the VA/NC border by
early Tuesday. The front will linger in the area through the
latter part of the week until a stronger cold front arrives from
the west. Temperatures are expected to remain above normal until
the weekend.

&&

.NEAR TERM /THROUGH MONDAY/...
-- Changed Discussion --
As of 950 PM EDT Sunday...

Key Message:

1). Scattered thunderstorms expected Monday afternoon,

2). Much warmer tonight than recent nights.

Forecast on track and should be a mild night. A few clouds
arrive across the I-64 corridor into the VA piedmont from
upstream convection after midnight. CAM models allow for a small
chance of a shower/storm shifting toward the WV mountains by
dawn, so have added just that small threat northwest of
Lewisburg, WV.

Previous discussion...

Gusty southwest winds evolved across the region today helping to
boost temperatures well over what we`ve had prior days. Temperatures
soared into the 70s and 80s after a cold morning in the 30s for
most areas. This pattern will continue overnight with urban
areas such as ROA only cooling into the high 50s or low 60s
tonight. A west- east oriented cold front will sag slowly
southward toward I-64 by afternoon. Models are not overly
favorable for convection, but the threat for convection is non-
zero for sure. Enough heating, instability, and dynamics along
with weak frontal forcing are present for isolated to scattered
thunderstorms to develop along this southward moving boundary by
afternoon. The main area of concern would be toward RIC, but
some convection could clip the northeast corner of the CWA mid
to late afternoon, with isolated activity developing back to the
west. To the west, upslope flow will result in thicker clouds
and a chance for showers by afternoon/evening. Made some minor
adjustments to pops to increase pops for the late
afternoon/early evening across the mountains of southwest VA,
but little change was made elsewhere. Kept pops at or below 40%
for the most part.

/Confidence Levels in Forecast Parameters/
- Moderate to High Confidence in Temperatures,
- Low Confidence in Precipitation Probabilities,
- Moderate Confidence in Wind Speed,
- High Confidence in Wind Direction,
- Low Confidence in Thunderstorm Potential.

Previous Near Term Discussion...
As of 220 PM EDT Sunday...

Key message:

 -  Enhanced Fire Danger this afternoon and evening

Will start to see high clouds from thunderstorms in Pennsylvania and
Maryland spread into central and southern Virginia overnight. Front
will move south tonight and Monday, reaching southwest Virginia and
southern West Virginia Monday afternoon. Some guidance was
suggesting axis of storms from Charleston, WV to Delaware Monday
afternoon and up to 2500 J/kg of CAPE Monday afternoon, mainly
after 4PM. Grand Ensemble also showed the highest probability of
precipitation in the late afternoon.

As mean flow has turned to the west and southwest region stays
in warm air advection. Wind speeds will be less gusty after
sunset and will remain mixed enough to keep overnight
temperatures mild. Highs on Monday will depend on the amount of
cloud cover in the morning but breaks of sunshine will be able
to tap into the warmer 850 MB temperatures.
-- End Changed Discussion --

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 220 PM EDT Sunday...

Key messages:

  - Several periods of showers and thunderstorms
  - Above normal temperatures Tuesday and Wednesday

Cold front advancing south stalls along the VA/NC border Monday
night before retreating back north late Tuesday. More widespread
coverage of showers and thunderstorms will be along the front,
but scattered to isolated storms will develop in the warm sector
Tuesday and Wednesday.

Seeing a push of stable air and cloud cover with northeast wind on
the cold side of the boundary in central and eastern Virginia on
Tuesday. This may result in a better coverage of showers and
thunderstorms in the mountains on Tuesday, and cooler
temperatures in the piedmont depending on eventual location of
the front and cloud cover.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 1250 PM EDT Sunday...

As of Key Points:

1). Active weather pattern with a threat for precipitation
in the forecast for portions of the area each day.

2). Thursday into Thursday night will be the least active time
period.

3). Best coverage of precipitation will be in the west.

4). Above normal temperatures Thursday and Friday trend to below
normal by Sunday.

A look at the 14 April 00Z NCEP Ensemble Mean 500 mb Geopotential
heights shows the following scenario Thursday through Sunday. A
shortwave trough which was over the Lower Ohio Valley Wednesday
evening, is expected to have lifted north and been absorbed within
the approach of an even stronger trough. This second, stronger
trough, is expected to head east into Quebec Friday evening with its
associated axis over our region. By Saturday, flow across our region
trends zonal with perhaps another upstream shortwave trough over
the Upper Mississippi Valley. This shortwave trough then becomes a
bit more amplified as is crosses the region on Sunday. At the
surface, low pressure will move from central Ontario Thursday
evening to central Quebec by Friday evening. Its associated surface
cold front will cross our region on Thursday. A second cold front in
association with a second and more potent trough is expected to
cross the region late Friday into Friday evening. The trailing frontal
boundary is then expected to move through the region Saturday.

Output from the 14 Apr 00Z Ensemble Situational Awareness Table
shows 850mb temperatures at a maximum on Thursday in the +12C to
+14C range on Thursday. The upper end of this range touches the 90
to 97.5 percentile of the thirty-year climatology. As we progress
into the weekend, temperatures trend downward, especially by Friday
night. Saturday into Sunday values are expected to range from
roughly 0C to +5C. Precipitable Water values across the area will be
at a maximum on Thursday in the 0.75 to 1.00 inch range on Thursday
and Friday. The numbers drop to 0.50 to 0.75 inch on Saturday to
around 0.50 inch on Sunday.

The above weather scenario points towards one that is not a washout
for the area. However, with frequent frontal passages resulting
in an unsettled weather pattern, it will be necessary to keep a
mention of showers and thunderstorms in the forecast through
this portion of the forecast will be common. Currently, the time
period with the least expected coverage is Thursday into
Thursday night. Temperatures are expected to be five to ten
degrees above normal Thursday and Friday, near normal Saturday,
then about five degrees below normal for Sunday.

Confidence in the above weather scenario is moderate.
Confidence is on the lower side with respect to timing and
impacts.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
As of 815 PM EDT Sunday...

Key Messages:

1). Mostly VFR Conditions Expected Through the TAF Valid Period,

2). Isolated to Scattered Thunderstorms Possible Monday
Afternoon/Evening,

3). Gusty Southwest Winds Decrease Slightly Through the Period.


Synopsis: VFR conditions are expected overnight with a warm and
dry air mass over the region. Scattered mid-high clouds will
drift south overnight from diminishing thunderstorms across PA.
These thunderstorms are focused along a slowly southward moving
frontal boundary. This frontal boundary will drift toward the
I-64 corridor by late afternoon Monday. Isolated to scattered
thunderstorms could develop along this front by afternoon.

Ceilings...VFR ceilings are expected through most of the TAF
valid period. SCT-BKN high end MVFR ceilings may develop across
southeast WV from BLF-LWB waste in the TAF valid period. SCT
thunderstorms may result in isolated pockets of sub-VFR
conditions after 19Z Monday.

Visibilities...VFR visibilities expected through the TAF valid
period outside of brief MVFR visibilities in any isolated
thunderstorms, with low possibility at a specific TAF site. LYH
has the greatest possibility of seeing sub-VFR visibilities
Monday after 20Z.

Winds...continuing SW-WSW through the TAF valid period at speeds
of 10-15 mph overnight and 10-20 mph Monday. Periodic gusts to
25 mph possible.

/Confidence Levels in Forecast Parameters/
- Moderate to High Confidence in Ceilings,
- Moderate to High Confidence in Visibilities,
- Moderate to High Confidence in Wind Direction and Speed,
- Low Confidence in Thunderstorm Potential.

Extended Aviation Outlook...

Mainly VFR through Tuesday, though cloud cover is expected to
increase. Seeing a push of stable air and cloud cover with
northeast wind on the cold side of the boundary in central and
eastern Virginia on Tuesday. This may result in a better
coverage of showers and thunderstorms in the mountains and MVFR
ceilings in the piedmont.

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 Wednesday and Thursday.

&&

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

&&

$$

SYNOPSIS...AMS
NEAR TERM...AMS/RAB/WP
SHORT TERM...AMS/RAB
LONG TERM...DS/VFJ
AVIATION...RAB