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000
FXUS61 KRNK 160155
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
955 PM EDT Mon Apr 15 2024

.SYNOPSIS...
A cold front will drop south to the North Carolina/Virginia
border tonight, then lift north as a warm front Tuesday
afternoon. The next low pressure system approaches the region
by the middle of the week. Temperatures are expected to remain
above normal until the weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 950 PM EDT Monday...

Key Message:

1. Severe Thunderstorm Watch expires 10pm.

2. A few showers/storms will be possible til midnight-1am mainly
over far SW VA.

Very little left on radar this evening except a couple of
stronger cells from BLF-KY/WV border. Airmass is stabilizing
with convection starting to become less robust. We escaped the
stronger storms earlier that slid by north and east of our VA
piedmont. One cell over Mercer this evening had a history of
producing up to golf ball sized hail. Trends show weakening but
quarter hail and wind gusts to 60 mph not out of the question.

Weak boundary and lingering theta-e advection bisecting southern
VA may keep a few showers around into early morning but by in
large the entire area should dry out. Question overnight is if
ample low level moisture develops behind front with low level
winds turning north to northeast. Could be a few areas with fog
and low clouds at dawn Tuesday so have increased sky cover
slightly with most having partly to mostly cloudy skies late
tonight. This will keep temps mild in the 59s.

Previous discussion from early evening...

Surface analysis at 7pm showed a frontal boundary stretching
from central KY into central VA. Convection has been mainly
widely scattered and mostly focused along the boundary
along/north of I-64 with only isolated weaker cells in our
forecast area. Will watch trends through 8-9pm and will likely
be able to drop part or maybe all of the watch. Of the high-res
models, only the 18z 3km NAM is showing redevelopment as the
outflow/boundary pushes south. Moisture convergence is pretty
meager and there is little upper support. Airmass is dry but
forecast soundings showing inverted V which could still support
some stronger gusts. The better CAPE/Theta-E air is across KY
and this area will see more development potential this evening.

Models also hint at patchy fog in the river valleys late
tonight.

Previous discussion...

Environmental parameters are favorable for severe thunderstorms
this afternoon and evening, including DCAPE and mid/low level
lapse rates. What little cap/CIN that is left is gone by 4PM and
as southwest winds diminishing much of the downsloping will also
erode. This puts the best timing for storms from 4PM-10PM this
evening.

Seeing some cumulus just starting to develop in the southern
Blue Ridge and remnant outflow boundaries from thunderstorms
earlier today in the north. Expectation is for scattered
thunderstorms in central and easter Virginia this afternoon then
isolated to scattered coverage west into the mountains this
evening.

Increasing dew points will result in mild overnight
temperatures. As the front dips into central and eastern
Virginia clouds and fog will fill in over the piedmont.
Locations that get rain in the afternoon and evening may have a
few hours of patchy fog once the storms move through. Only minor
changes to temperatures overnight. May set a couple record warm
minimum temperatures for April 15th.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 240 PM EDT Monday...

Key Messages:

1: Scattered showers and storms Tuesday and Wednesday

2: Temperatures above normal ahead approaching frontal system


A warm front will retreat to the north on Tuesday, moving the best
chances for storms north of the CWA. However, in the warm sector of
an approaching frontal system, we will see scattered to isolated
showers and storms around the area. The best coverage on these days
is likely to be in the mountains west of the Blue Ridge, while some
more stable air further east in the Piedmont and central VA will
limit coverage. Temperatures will be in the in the upper 70s
and 80s in the warm sector and slightly cooler north of the
front, depending on how much cloud cover there is in the
morning.

An west to east moving cold front will continue the chance of
showers and thunderstorms on Wednesday. The region will be well
into the warm sector leading to above normal temperatures.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 1225 PM EDT Monday...

Key Messages:

1. Isolated to scattered coverage of showers and storms Friday and
Saturday with the best coverage over the mountains.

2. Decreasing precipitation chances Sunday into Monday.

3. Initially temperatures above normal Friday, but trending to below
normal by Monday.

A look at the 15 April 00Z NCEP Ensemble Mean 500 mb Geopotential
heights shows the following scenario Friday through Monday. On
Friday, an upper trough will be centered over Hudson Bay with its
axis extending south into the Eastern Great Lakes and Lower Ohio
Valley. This feature will pivot east and northeast through Monday,
eventually placing our region with more or less a zonal flow.
Before we reach that zonal flow, there may be a wrinkle or two
within the flow in the form of a shortwave through the crosses the
region on Sunday. At the surface, expect low pressure over southern
Quebec on Friday, with an associated cold front extending south then
southwest curving over, or close to, our region on Friday. By
Saturday, limited movement eastward of this front is expected. While
high pressure is starting to make headway into western portions of
the area on Sunday, the cold front may still be in close proximity.
By Monday, the front will have moved even farther east, off the
coast of the Carolinas.

Output from the 15 Apr 00Z Ensemble Situational Awareness Table
shows 850mb temperatures around +12C to +13C over the region Friday.
Through the weekend values decrease to +4C to +8C by Saturday and
+2C to +4C by Sunday. Similar values are expected Monday.
Precipitable Water values will average around 1.00 inch Friday, 0.75
to 1.00 inch on Saturday and Sunday, and 0.50 to 0.75 inch for
Monday.

The above conditions should result in period where showers and some
storms will be more abundant Friday into Saturday, start decreasing
in coverage on Sunday, and have limited or no coverage by Monday.
The bulk of any showers and storms will occur around peak heating of
the day into and through the evening hours. Coverage most days will
be greatest across the mountains. Temperatures will average about
ten degrees above normal for Friday, near or slightly above normal
Saturday, near or slightly below normal Sunday, and near normal
Monday.

Confidence in the above scenario in broad terms is moderate, but
still lower in confidence regarding specific timing and coverage of
the precipitation.

&&

.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
As of 725 PM EDT Monday...

Could see showers/maybe TSRA in vicinity of LWB/DAN this evening
but overall coverage is isolated so amendments if necessary
will occur if storms look to move across. Did put in some tempo
group for showers based off the 18z NAM.

Once we clear out tonight, flow turns north/northeast. Models
leaning toward dry low levels, though pattern favors potential
for MVFR to possibly IFR stratus forming from LWB-LYH/DAN
between 09-15z. Low confidence but something to monitor. Where
it rains today, could be areas of patchy MVFR to IFR fog late
tonight and early Tues. Have LIFR at KLWB.

As front lifts north Tuesday afternoon should be VFR areawide.
Showers/few storms may develop and move across the mountains but
too small to have in tafs at this point.

Extended Aviation Outlook...

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 through Saturday, especially each
afternoon and evening. Most of the time should be VFR. Could
also have some fog at night.

&&

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

&&

$$

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