240
FXUS61 KRNK 120758
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
358 AM EDT Mon May 12 2025

.SYNOPSIS...

An upper level low over the Lower Mississippi Valley will track
slowly northeast into the Mid Atlantic region Tuesday and
Wednesday. This will result in a prolonged period of rain
starting today. Heavy rain and flooding are possible for our
area today through Tuesday night, especially along the Blue
Ridge and the eastern foothills where rainfall amounts will be
the highest.

&&

.NEAR TERM /THROUGH TODAY/...
As of 330 AM EDT Monday...

Key Messages:

1) The Flood Watch has been expanded to include Rockbridge,
   Botetourt, and Amherst Counties.
2) Widespread moderate to heavy rainfall will overspread the
   area today.

An upper level low will slowly lift out of the lower Mississippi
valley towards northern Mississippi and Alabama by this
afternoon. As this upper level low continues north, the regions
PWATs will surge into the 1.5-1.75 inch range areawide. This
will allow for efficient warm rain processes across the area,
which will only be enhanced in certain upslope regions
throughout the day. Additionally, a 80-100 knot 250mb jet
streak on the east side of the upper level low will approach the
region today, which will provide widespread forcing for ascent
for the region as much of the area will be on the left exit
region of this jet streak. Shower activity is already being
observed across NW North Carolina, and this is only expected to
expand north throughout the day.

Expansive cloud cover over the region today will limit
instability, which may lead to less chances for thunder across
the area; however, surface dewpoints should rise enough into the
low 60s through the late afternoon and evening that SBCAPE
values may rise to the 100-500 J/Kg range across the area. This
may lead to more widespread thunder chances during the late
evening and overnight hours as instability increases.

Given the extensive cloud cover today, high temperatures will
generally remain in the mid 60s to upper 60s across the area.
Lows tonight look to drop into the upper 50s to low 60s.

&&

.SHORT TERM /TUESDAY THROUGH FRIDAY MORNING/...
As of 330 AM EDT Monday...

Key Messages:

1) Flood Watch continues into Tuesday afternoon

2) Precipitation continues into the middle of the week

The cut-off low will make its way from the Deep South into the Mid-
Atlantic this week and will continue to provide precipitation
chances all day Tuesday and into Wednesday. Rainfall totals will be
the largest on Tuesday compared to Wednesday with the largest
accumulations towards central VA. Tuesday rainfall amounts between
the Blue Ridge and Central Piedmont of VA may be up to another 1-
1.5." The Flood Watch has been expanded to take this into account.
Residual rain will likely continue on Wednesday but additional
accumulations may not be greater than 0.25" for most of the region.
There is still some model disagreement on which part of the region
will get the most rain. 850mb winds are more southwesterly by
Wednesday so the Blue Ridge may not receive the bulk of the rain
that day. General thunderstorms are possible within these
showers for Tuesday and Wednesday with marginal CAPE and lapse
rates.

The cutoff low is projected to to be reabsorbed with the westerly
flow and 500mb ridging begins to build over the Mid-Atlantic
later this week. A warm front will start to approach from the
west from a surface low in the northern Great Plains.


&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 330 AM EDT Monday...

Key Messages:

1) Another chance of thunderstorms this weekend

2) Warming trend to begin

Ridge riders will offer a few opportunities for thunderstorms and
precipitation this weekend. Temperatures are projected to warm up
with highs in the mid-80s east of the Blue Ridge. This combined with
sustained dew points in the 60s, plenty of CAPE, and shear, there is
a potential set up for organized convection. It is too early to know
for certain whether these storms will become severe, but it is
something that will be monitored as we head into the work week.
Otherwise, at least one cold front is projected to pass through
after the storms this weekend followed by ridging over the
southeastern CONUS.


&&

.AVIATION /07Z MONDAY THROUGH FRIDAY/...
As of 115 AM EDT Monday...

MVFR to LIFR CIGs are starting to slowly penetrate into the
region tonight. These restrictions are expected to last through
the entire TAF period, with VSBYs also dropping to MVFR to IFR
levels.

Shower activity will spread north today through the morning and
afternoon hours to all terminals. This is what will lead to the
aforementioned visibility restrictions at most terminals during
this taf period.

Overall winds will be east and under 10kts, but BLF appears to
be nudging into the southeast flow and gusting to 20kts Monday.
This may send cigs back above 1kft though confidence is low on
this.


EXTENDED AVIATION OUTLOOK...

Confidence is high in the likelihood of widespread rain,
widespread MVFR/IFR ceilings, and up & down visibilities during
the period through Wednesday as an upper level low pushes north
through the area. However, some breaks are possible once the low
moves across the central Appalachians Tuesday night-Wed.

Thursday and Friday the rainfall will become less widespread and
more scattered. Overall flight conditions will be VFR to MVFR,
though potentially lower in late night fog if we clear out.

&&

.HYDROLOGY...
As of 155 PM EDT Sunday...

Models were starting to come into better consensus with the
precipitation amounts expected through Wednesday night. High
confidence that the largest total will be along the crest of the
Blue Ridge and in the eastern foothills.  Prolonged rainfall rates
of 0.5 inch/hour will enhance the threat of flooding, especially on
Monday into Tuesday. Rainfall amounts of 2 to 4 inches by
Wednesday morning along and east of the Blue Ridge and 0.5 to 2
inches west of the Blue Ridge are expected. There is the
potential for localized higher rainfall rates up to 3 inches/per
hour and total rainfall more than 5 inches.

The amount of moisture available also supports flood threat as
precipitable water values being advected into the area and up
the east slopes of the central Appalachians are 2 to 3 standard
deviations above climatological normals.

The main concern will be flash flooding. Rivers are running
low across the area, and can sustain runoff from widespread
heavy rainfall, especially with foliage back on trees across the
region; however, longer range model ensemble guidance for the
Dan River does show the potential for minor flooding at South
Boston.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Flood Watch through Tuesday afternoon for VAZ015>017-022-
     032>034-043>045.
NC...Flood Watch through Tuesday afternoon for NCZ001>006-018>020.
WV...None.

&&

$$

SYNOPSIS...AMS
NEAR TERM...EB
SHORT TERM...CG
LONG TERM...CG
AVIATION...EB/WP
HYDROLOGY...AMS