Flooding and Heavy Rain in Virginia, May 23 to 24, 2022

Area Forecast Discussion
National Weather Service Blacksburg VA
649 AM EDT Mon May 23 2022

.SYNOPSIS...
A stalled front to our south will be the focus for rain today
into Tuesday. Another low pressure system arrives by Thursday
with more showers and storms.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 200 AM EDT Monday...

Flooding May Become A Concern This Afternoon-Evening Over the NC
Mountains...

Front has moved just south of the forecast area this morning. Low
pressure at the surface near the Florida Panhandle/Alabama coast
this morning is going to track northeast along the front this
afternoon reaching central NC by late evening. Flow turning
southeast to south in the low levels will bring moisture overrunning
the front later this morning with rain overspreading the entire
area through the day.

Forecast challenge will be how much rain falls/thunder chances of
impact of cool side of front on temperatures.

In essence, wedge front will allow for a focus of decent lift but
deeper convection per latest model solutions should stay mainly to
our south today through tonight, though some elevated instability
may allow for some storms being embedded in the rain. This is mainly
more likely near the wedge front across the far SW VA into NC
mountains/foothills. The area from Carroll County VA southwest to
the NC mountains had more rainfall yesterday. Given this, confidence
is increasing on at least localized threats of flooding/flash
flooding potential this afternoon/this evening, but at the same
time, we've been fairly dry, so will see how radar/rainfall evolves
today for any watch potential.

Blend of high-res models and national center forecast shows 2+
inches of rain through 12z Tuesday along the NC mtns/Blue Ridge with
most seeing 1"+, with lowest amounts north of I-64 between 1/2 to 1
inch.

Aside from the rain, cool but damp easterly flow with wedge will
likely keep temperatures down in the 60s for most today, even though
we are starting in the 60s this morning. Will have highs about 5
degrees warmer than lows.

Tonight, the front remains locked from the lower TN Valley east
across the Carolinas. Wave moves east toward pre-dawn Tuesday so
should start to see a downward trend from west to east in the
heavier/widespread showers, but think the piedmont stays rainy into
Tuesday morning before 8am.

Lows should be a little cooler with north side of front tonight with
mid 50s to around 60 for most, but still damp.

Forecast confidence is high on rain chances and sky cover, but
average on temperatures today and thunder chances.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
As of 415 AM EDT Monday...

     Wedge sets up, rainy for most of the week...

By Tuesday, high pressure will be situated over New England/southern
Canada such that it wedges drier and cooler air on the east side of
the Appalachians. This will interact with warm moist air being
brought by southeasterly flow on the west side of a surface high and
upper ridge off the southeastern CONUS coast and introduce a good
amount of isentropic lift. This CAD setup will last all of Tuesday
and most of Wednesday before an approaching front and deep trough
usher the northern high pressure out to sea sometime Thursday.

Rain chances will remain in the forecast almost the entirety of this
forecast period, with rain letting up slightly in the overnight
periods. Highest rain totals in the mid-week will be in northwest NC
where the greatest amount of moist air will reside, as well as some
small contribution from orographics compounds the isentropic
lifting. Expecting about 1-1.5 inches total in that region, with
around 0.25-0.5" towards central VA/I-64 corridor.

With fropa on Thursday, expecting more thunderstorms than Tues/Wed,
as dynamics associated with the front encourage a convective mode.
Some of these storms could be strong, so this will be a time period
under more scrutiny once we are near enough that high-res guidance
is available.

Temperatures will be solidly below normal for this time of year
during the wedge Tues/Wed, especially east of the Blue Ridge. Highs
in the 60s and low 70s for the entire CWA are forecast. Thursday
will see daytime highs warm up back towards normal, as the wedge is
broken and southeast/southerly flow will help warm things. Highs in
the 70s/low 80s Thursday afternoon.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
As of 415 AM EDT Monday...

     Ridging returns, dry and warm weekend...

Behind the front on Thursday/Friday, ridging will build in and
heights will rise for much of the weekend. This will suppress cloud
formation and rain chances through Monday, which will be a change of
pace from the rainy week just prior. The solid and persistent
ridging will help temperatures rise again, getting a few degrees
above normal by Monday afternoon.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
As of 640 AM EDT Monday...

Area of lower ceilings with rain will move across the area from
southwest to northeast through the day, with sub-VFR cigs/vsbys
from moderate to heavy showers impacting most by this afternoon.

Ceilings/vsbys will fluctuate but overall flavor will be poor
flying conditions with low MVFR to LIFR at times.

Rain will start to taper off in the mountains west of BCB/ROA
late tonight but cigs/vsbys will stay low.

Winds overall will run northeast to east at 5-10kts. Some gusts
to 20kts possible at LYH/DAN but for short windows.

Thunder chances are limited so no mention in the tafs.

Forecast confidence is average on ceilings/vsbys this morning,
and above average on sub-VFR weather for most of the 12-06z taf
period.

Extended Aviation Discussion...

Stalled front to our south will maintain cloud cover across the
region through at least Thursday with daily chances for showers.
This will result in prolonged sub-VFR conditions.

On Friday the Mid Atlantic region and Carolinas will be back in
the warm sector with a lower probability of precipitation and a
much better chance of VFR flight conditions.

&&

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

&&

SYNOPSIS...PM/WP
NEAR TERM...WP
SHORT TERM...VFJ
LONG TERM...VFJ
AVIATION...AMS/PM/WP

Hazardous Weather Outlook
National Weather Service Blacksburg VA
422 AM EDT Mon May 23 2022

NCZ001>006-018>020-VAZ007-009>020-022>024-032>035-043>047-058-059-
WVZ042>044-507-508-240830-
Ashe-Alleghany NC-Surry-Stokes-Rockingham-Caswell-Watauga-Wilkes-
Yadkin-Tazewell-Smyth-Bland-Giles-Wythe-Pulaski-Montgomery-Grayson-
Carroll-Floyd-Craig-Alleghany VA-Bath-Roanoke-Botetourt-Rockbridge-
Patrick-Franklin-Bedford-Amherst-Henry-Pittsylvania-Campbell-
Appomattox-Buckingham-Halifax-Charlotte-Mercer-Summers-Monroe-
Eastern Greenbrier-Western Greenbrier-
422 AM EDT Mon May 23 2022

This Hazardous Weather Outlook is for north central North Carolina,
northwest North Carolina, central Virginia, south central Virginia,
southwest Virginia, west central Virginia and southeast West
Virginia.

.DAY ONE...Today and tonight.

Rain may be heavy at times this afternoon into tonight. Flooding of
poor drainage and low lying areas will be possible. Minor flooding
of creeks and streams will also be possible.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday.

There is a low probability for widespread hazardous weather.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.