814
FXUS61 KRNK 281043
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
643 AM EDT Fri Jun 28 2024

.SYNOPSIS...
High pressure will track across the mid-Atlantic states today,
then shift northeast off the New England coast Saturday. A
frontal boundary to our south will keep moisture around
into Saturday, with chances for showers and storms. Another
front moves in from the northwest Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 130 AM EDT Friday...

Key Messages:

1) Upslope scattered showers/few storms through Friday night.

2) Less humid today but increasing again Friday night.

There is a low level theta-e ridge strung across the Blue Ridge
this morning with low level convergence. This has resulted in
isolated showers. Slow movers but weak and models are fading
this out through the early morning but would not be surprised
for a pop up shower to form at times.

For today, southeast flow will increase as high pressure works
across the mid-Atlantic, while a front stays situated from the
coast of NC into the Gulf Coast states. Seems as we head through
the morning, dewpoints will start to drop across western and
northern sections of our forecast area (WV through the central
VA piedmont), but could keep higher RH across southside VA into
NC closer to the front.

Models are varying on convection today, and leaned toward a
blend of the Hi-RES ARW/FV3, which will have chance pops
situated across the NC mountains and foothills northward to the
souther Blue Ridge and Mountain Empire of SW VA, this afternoon,
with less to no coverage northeast of a Lewisburg to Danville
line. Confidence is high that storms will be limited as
instability seems lacking but enough heating could produce a few
storms, but nothing severe. Showers and storms will be slow
movers so some heavy rainfall appears likely but most will see
little or no rain.

Tonight, expect a lull in the evening but moisture starts to
ramp up again after midnight, that will see widely scattered
showers over most of the mountains/foothills, with 20 to 30
percent chance of getting any measurable rainfall, with slightly
higher chances again over the NC mountains/foothills northeast
along the Blue Ridge into Patrick/Carroll counties in VA.

Highs to will be close to normal as we have a mix of sun and
clouds with more clouds across the Blue Ridge and either side.
Temps will range from the mid 80s to near 90 east of the Blue
Ridge, to upper 70s to mid 80s west.

Tonight, as dewpoints rise and cloud cover starts to increase,
thinking lows will be on the warm/muggy side with upper 60s to
around 70 for most of the region.

Forecast confidence is high on temperatures and winds, and
average on sky cover and shower/storm coverage.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
As of 100 AM EDT Friday...

Key Points:

1. Well above normal temperatures Saturday and Sunday.
2. Showers and storms Saturday and Sunday, some with locally heavy
rain and strong/damaging winds.
3. Drier and cooler for Monday.

A look at the 27 June 12Z NCEP Ensemble Mean 500 mb Geopotential
heights shows an upper level trough over the Upper Mississippi River
Valley on Saturday morning, with southwest flow across our region.
As we progress into Sunday and Monday, this trough is expected to be
over the Great Lakes Sunday morning and just east of our region
Monday morning. By Monday night, the trough will be centered over
the Canadian Maritimes with ridging building into the Ohio Valley. At
the surface on Saturday morning, low pressure is expected to be over
Michigan with a southwest trailing cold front into MO/KS/OK/AR. By
Sunday morning, this front is expected to be over our region. High
pressure will be nosing into the region from the west Monday
morning, and be centered overhead by late Monday night.

Output from the 27 June 12Z Ensemble Situational Awareness Table
shows 850mb temperatures on Saturday around +16C to +18C over the
region and +18C to +20C for Sunday. For sections of the region the
upper end of these ranges correspond to the 90 to 97.5 percentile of
the 30-year climatology. For Monday, values drop notably reaching
the +12C to +14C range over the area, with the low end of this range
within the 2.5 to 10 percentile of climatology. Precipitable water
values for Saturday are expected to be very high for this time of
year with numbers around 2.00 inches. This places the western half
of the region higher than the 99.5 percentile of the 30-year
climatology and the eastern half with a range in the 97.5 to 99.5
percentile. This swath of extraordinary high values sweeps across
the region Saturday night immediately in advance of the a cold
front. On Sunday, drier values work their way into the region by the
afternoon, but values in the forenoon, especially in the southeast
sections, will remain very high. Sunday night into Monday
night, precipitable water values are expected to continue to
fall. Values of 0.50 to 0.75 inch are expected by Monday into
Monday night, or values within the 2.5 to 10 percentile of the
30-year climatology.

The above weather scenario offers a Saturday with very good
probabilities of showers and storms that contain moderate to heavy
rainfall. Temperatures are expected to be well above normal.
Additionally, The Day-3 Severe Thunderstorm Outlook from SPC offers
Marginal Risk of severe weather generally for areas along and west
of the Interstate-81 corridor. Damaging winds would be the greatest
threat. On Sunday, while well above normal temperatures continue,
the details are not as clear on the precipitation timing. However, a
cold front looks to arrive early and then lingers over eastern parts
of the region through mid-day and/or the passage of the 850mb cold
front helps to maintain showers and storms across mainly eastern
parts of the region. By Sunday night, cooler and drier air is
expected to be entering the region with this pattern continuing into
Monday night.

Confidence in the above weather forecast is moderate to high.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
As of 100 AM EDT Friday...

Key Points:

1. Temperatures and humidity trending higher each day.
2. Chance of showers/storms late Wednesday night into Thursday.

A look at the 27 June 12Z NCEP Ensemble Mean 500 mb Geopotential
heights shows a building upper ridge over the Southeast US. Nearly
zonal flow is expected near the US/Canadian border. The exception is
a shortwave trough that is expected to progress from the Dakotas on
Thursday morning to Upper Mississippi Valley by late Thursday night.
At the surface on Tuesday morning, high pressure will be centered
over the area. By Wednesday morning, the high will start shifting
east of the region as a cold front approaches through the Ohio
Valley. By Thursday morning, the cold front will be over or near our
region.

Output from the 27 June 12Z Ensemble Situational Awareness Table
shows 850mb temperatures around +16C for Tuesday, +19C to +21C for
Wednesday, +20C to +22C on Thursday. The upper end of the range on
Wednesday falls within the 90 to 99 percentile of the 30-year
climatology. On Thursday, much of the area is expected to be within
the 97.5 to 99 percentile of climatology with potentially the
mountains of North Carolina higher than the 99 percentile. For
precipitable water values on Tuesday, expected numbers around or
just shy of 1.00 inch. Values climb on Wednesday to around 1.50
inch. For Thursday, numbers climb more to 1.75 to 2.00 inches, or
within the 90 to 97.5 percentile of the 30-year climatology.

The above weather scenario offers a period of rebuilding heat and
humidity after the cooler and drier Monday. Temperatures should
trend higher each day. Primarily dry conditions are expected until
late Wednesday night and Thursday with the approach/arrival of a
cold front and the airmass in advance of it trending progressively
unstable.

Confidence in the above weather forecast is moderate to high.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
As of 150 AM EDT Friday...

High probability for VFR for terminals through the period. Some
MVFR ceilings are possible at BLF/BCB/ROA if showers move across
but coverage today looks limited more toward the NC mountains,
south of ROA/BCB/BLF.

Overall anticipate SKC/SCT clouds this morning, then scattered
to broken in the 4-8kft range today into this evening, with
again possible 2-3kft cigs along the Blue Ridge south of
ROA/BCB.

Winds will be light this morning then turning east to southeast
today and increasing to 8-12kts especially west of the Blue
Ridge. Cannot rule out a few gusts to 20kts around BLF.

Ceilings will lower to MVFR possibly IFR after 07z at most
sites. A few showers possible but too low chance to have in the
tafs.


EXTENDED AVIATION OUTLOOK...

A greater coverage of thunderstorms and associated MVFR flight
conditions is expected Saturday and Sunday, but VFR outside of
any storms.

Monday-Tuesday appears to be VFR as high pressure works in from
the north.

&&

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

&&

$$

SYNOPSIS...VFJ/WP
NEAR TERM...WP
SHORT TERM...DS
LONG TERM...DS
AVIATION...RCS/WP