000
FXUS61 KRNK 280809
AFDRNK

Area Forecast Discussion
National Weather Service Blacksburg VA
409 AM EDT Sun Apr 28 2024

.SYNOPSIS...
A strong low pressure system will track from the Central Plains to
the Great Lakes today and Monday while high pressure was off the
East Coast. This system will push and cold front through the region
on Tuesday bringing a chance of showers and thunderstorms.
Temperatures will remain above normal through the middle of the
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 345 AM EDT Sunday...

Key message:

 -  Above normal temperatures

A short wave tracking across the northern periphery of the upper
ridge was creating some mid level clouds over central and eastern
Virginia early this morning. Bufkit forecast soundings showed winds
from the surface through mid levels of the atmosphere will be mainly
from the southwest today and tonight. 500 MB heights and 850 MB
temperatures(in the +12 to +16 range) were above normal but not by
excessive amounts.

Upper ridging over the southeast United States will provide
synoptic scale subsidence but a shallow layer of moisture along
the eastern slopes of the Blue Ridge this morning and
stratocumulus this afternoon will prevent maximizing the heating
today. Temperatures will be starting out mild so will easily
rise into the lower 70s to lower 80s by the afternoon.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
As of 135 AM EDT Sunday...

Key Points:

1. Notably warmer for Monday
2. Slightly cooler, but still above normal temperatures Tuesday and
Wednesday.
3. Scattered showers and storms for Tuesday -- best coverage over the
mountains

A look at the 27 April 00Z NCEP Ensemble Mean 500 mb Geopotential
heights shows a ridge over our region on Monday. On Tuesday, a
shortwave trough crosses through the northern extent of the ridge.
By Wednesday, the ridge builds back over the region. At the surface,
on Monday, high pressure is expected to be centered off the coast of
the Carolinas, and a warm front will be near the Mason-Dixon line.
By Tuesday, a weak low/trough is expected to move through the mid-
Atlantic region. By Wednesday, the trough is over the western
Atlantic.

Output from the 27 Apr 12Z Ensemble Situational Awareness Table
shows 850mb temperatures on Monday across the region within the
+14C to +16C range, or numbers which fall within the 90 to 99
percentile of the thirty-year climatology. By Tuesday and Wednesday,
numbers are lower, close to +12C to +13C, but still on the mild side
of normal. Precipitable water values across the region on Monday
will average 0.75 to 1.00 inch. These numbers increase to 1.00 to
1.25 inch Tuesday, then fall back to 0.75 to 1.00 inch for Wednesday.

The above scenario offers a period of above normal temperatures,
with high temperatures on Monday described by some as hot. The
passage of a weak disturbance and front will bring some showers and
storms to the area on Tuesday with the best coverage across the
mountains. Primarily dry conditions quickly return on Wednesday as
high pressure again builds across the area.

Confidence in the above weather pattern is moderate to high.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
As of 105 AM EDT Sunday...

Key Points:

1. Continued above normal temperatures
2. Increasing chances of showers and storms with the best coverage
on Saturday

A look at the 27 April 00Z NCEP Ensemble Mean 500 mb Geopotential
heights shows a nearly zonal pattern aloft across the region. By
Saturday, there are hints within the averaging of a shortwave trough
potentially over the Great Lakes region. At the surface, a weak ridge
of high pressure will be over our area on Thursday while a trough
approaches the Great Lakes region. On Friday, this same trough
continues to make slow progress towards our region, but with notable
variability within the ensemble members. For Saturday, the average
position of the trough shifts to New England with a trough axis
perhaps extending into the Lower Ohio and Tennessee Valleys.

Output from the 27 Apr 12Z Ensemble Situational Awareness Table
shows 850mb temperatures on Thursday within the +14C to +16C range,
or around the 90 to 97.5 percentile of the thirty-year climatology.
On Friday, these numbers are only slightly cooler, closer to the
+14C range. Finally, by Saturday values are a slightly cooler still,
closer to +12C to +13C, but still on the mild side of normal.
Precipitable Water values across the region on Thursday are expected
to average 1.00 inch. Numbers increase to 1.00 to 1.25 inch on
Friday and Saturday.

The above scenario offers a pattern of increasing moisture in
advance of an approaching upper trough. Ensemble averaging has
erased some of the finer shortwaves some of the deterministic
guidance during this portion of the forecast. Compared to twenty-
four hours ago, the timing of the arrival of the strongest shortwave
trough has slowed, placing the time period of the best coverage of
showers and storms on Saturday.

Confidence in the overall synoptic pattern during this portion of
the forecast is moderate. However, for the timing of finer shortwave
features within the main flow, confidence is low. Confidence in
above normal temperatures is moderate to high.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
As of 400 AM EDT Sunday...

A short wave tracking across the northern periphery of the
upper ridge was creating some mid level clouds over central and
eastern Virginia early this morning. VFR to MVFR clouds were
also spread in the foothills of Virginia and North Carolina.
There clouds may expand into KROA and KBCB before 10Z/6AM.

Bufkit forecast soundings showed winds from the surface through
mid levels of the atmosphere will be mainly from the southwest
today and tonight. Upper ridging over the southeast United
States will provide synoptic scale subsidence. The layer of
moisture along the eastern slopes of the Blue Ridge early this
morning was shallow and is expected to dissipate by 14Z/10AM.

Scattered to broken, flat stratocumulus may also develop this
afternoon with ceilings from 4-5Kft. A majority of this cloud
cover will dissipate around sunset.

Extended Aviation Outlook...

Monday should be mainly VFR with southwest winds. NW winds
arrive behind a cold front crossing the area Tuesday with
TSRA and MVFR or lower ceilings. Widely scattered
SHRA/TSRA will be possible again each afternoon on Wednesday and
Thursday.

&&

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

&&

$$

SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...DS
LONG TERM...DS
AVIATION...AMS