889
FXUS61 KAKQ 150831
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
431 AM EDT Mon Jul 15 2024

.SYNOPSIS...
A very hot stretch of weather prevails today through most of
Wednesday. An unsettled period returns late Wednesday through
Thursday, as a cold front pushes through the area and stalls
across the Carolinas. Shower chances focus mainly over southern
Virginia and North Carolina Friday, then return to all zones by
Saturday.

&&

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

Key Messages:

- Hot and humid east, hot and slightly less humid west.

- Excessive Heat Warning in effect SE zones (added
  Bertie/Hertford NC to the Warning).

- Heat Advisory in effect for most of the remainder of the area
  except the piedmont and MD beaches (added Caroline/western
  Hanover to the Advisory).

The latest analysis indicates a weak sfc trough over the region
(actually a bit of a sfc low over Maryland). Aloft, a westerly
flow prevails with a broad trough across central and eastern
Canada, and a broad ridge from the Four corners region extending
east to the SE CONUS. Warm and humid this morning with
temperatures in the mid 70s to around 80F and dew pts in the
70s. With the sfc low to the N, enough mixing with a SW low
level wind has inhibited any fog development and the sky is
mostly clear. A few isolated/widely scattered showers/storms
may develop again this aftn with the highest PoPs to ~30% over
the far NW for storms developing on the mountains drifting east,
and across NE NC where the highest low level moisture will
reside. The primary concern for today will be the heat/humidity.
Yesterday, the dew pts stayed on the higher edge of guidance
over RIC metro, but today we expect to see deeper mixing and
even the typically high bias guidance (NAM/NBM),show dew pts
dropping at peak heating this aftn along and W of I-95. With
that said, highs in the upper 90s to around 100F are expected,
so have decided to expand the Heat Advisory slightly west to
include Caroline and all of Hanover, and to expand the Excessive
Heat warning a tier W into Bertie/Hertford NC. Overall, a very
hot day expected with record highs possible (see climate section
for details). Any convection this aftn should quickly wane after
sunset, with mostly clear skies overnight. Lows will be mainly
in the mid to upper 70s with a few urban areas perhaps not
dropping below 80F. Will allow dayshift to determine if the
Excessive Heat Warning in the SE will be extended through the
night and through Tuesday (a good chc that Tuesday is even worse
so Excessive Heat may need to expand west at least a tier or two
of counties).

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 400 AM EDT Monday...

Key messages:

- Tuesday will likely see peak heat indices slightly higher than
  Monday. Excessive Heat warnings are expected for at least the
  E/SE, possibly all the way to metro RIC (with Advisories
  expected elsewhere).

- Remaining hot Wednesday and humid area-wide but with a higher
  coverage of storms by afternoon (heat headlines are likely for
  some of the area but details are more uncertain)

The combination of heat and humidity peaks on Tuesday, as the
core of the upper ridge becomes centered well off the SE coast.
The consensus is for 850mb temperatures similar to Monday
(21-22C), with slightly higher humidity given the favorable
location of the upper ridge off the SE coast to Bermuda. Even
inland areas should have dew pts remaining at least around 70 to
the lower 70s during peak heating. Therefore, with highs again
into the mid/upper 90s to around 100F, peak heat indices of
110F+ are expected to prevail over roughly the SE 1/2 of the
CWA, potentially encroaching on the RIC metro and eastern shore.
Limited rain chances again, with the CAMs a bit split on where
the highest chances will be. Overall, there is a bit higher chc
over the southern piedmont, with PoPs up to ~30%, with
generally 15-20% or less elsewhere. Warm and humid again Tue
night (probably the warmest night with lows 75-80F).

The models remain in decent agreement that Wednesday will be
the last day of hot conditions as the upper ridge eventually
breaks down, as a strong upper trough translates SE from north
central US to the Great Lakes. Dew pts will be more uniform
area-wide (in the mid 70s inland with upper 70s SE), due to
moisture pooling along a pre- frontal trough. Highs will be a
few degrees less Wednesday (mid- upper 90s) but the higher dew
pts may lead to similar heat indices with 110F+ possible in the
E and SE. Some of the models depict some shower activity as
early as midday, so will continue with isolated tstms will be
by early aftn, with scattered showers/tstms developing by mid
aftn and beyond (highest PoPs west). Likely to high chc PoPs Wed
evening.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 420 AM EDT Monday...

Key Messages:

- The cold front slowly pushes through the area Thursday,
  locally heavy rain and highest PoPs shift S through the day.

- The front stalls near or just south of the area Fri, then
  lifts back north over the weekend.

00z/15 models remain in fairly good agreement that the upper
level trough pushes from the upper Great Lakes to New England
Thursday, but flattens out to the south as it approaches the
strong/persistent upper level ridge anchored well offshore of
the SE US coast. A fairly strong shortwave is progged to move
from the eastern Great Lakes to New England Thu night (per the
GFS/ECMWF), which will tend to drop the sfc front and deeper
moisture S of the CWA by Friday. The consensus remains for the
upper ridge to then retrograde west and become centered closer
to the SE US coast into next weekend. Will have the highest
chances for showers/storms Thursday (~70%) for southern VA/NE
NC, with 50-60% N). Locally heavy rainfall will certainly be
possible during this timeframe. Highs Thursday will be highly
dependent upon the timing of the front, for now expecting mid
80s to near 90F. Not as hot, but still humid Friday (south)
and all areas Saturday with highs mostly in the low- mid 80s.
Friday is staring to look like it may be mainly dry for the
northern 1/2 of the CWA as drier air pushes into northern
portions of the FA with broad sfc high pressure building east
from the Great Lakes. As the upper levels ridge moves closer to
the SE coast Saturday, the flow aloft increases from the SW and
expect to see more humid air even into northern zones by that
time. Lowered PoPs to 20% or less Friday across the north,
maintaining high chc PoPs (40-50% south). Then have chc PoPs all
areas for Saturday-Sunday. Highs warm to 85-90F Sunday as the
boundary washes out.

&&

.AVIATION /09Z MONDAY THROUGH FRIDAY/...
As of 200 AM EDT Monday...

VFR conditions should continue through the 06z TAF period.
Could see isolated-widely scattered tstms NW of RIC later this
aftn into the evening, and also over NE NC but confidence is
very low that the tstms will actually reach RIC (PoPs ~15%) or
ECG (PoPs ~20%). Winds will remain S-SSW with speeds below 12
kt.

VFR conditions continue tonight through early Wednesday.
Shower/tstm chances increase Wednesday aftn through Thursday
with periodic flight restrictions expected ahead of a slow
moving cold front. A lower chc for precip Friday (except over
the SE).

&&

.MARINE...
As of 315 AM EDT Monday...

Key Messages...

- Generally quiet marine conditions expected today and Tuesday
  with increasing SW winds expected ahead of a cold front
  Wednesday into Thursday.

Surface ridge remains anchored off the SE CONUS with weak lee
troughing noted over inland portions of the local area. Flow aloft
is weakly zonal with strong ridging over the Four Corners and the
main jet displaced well to the north along the US/Canadian border.
Winds are SW 10-15 kt this morning over the waters. Waves in the
Ches Bay are 1-2 ft with seas 2-3 ft.

Inland lee trough will be quasi-permanent through the first
half of the week as flow aloft remains zonal. Expect sub-SCA S
and SW winds today and Tuesday. A cold front drops southward
Wednesday into Thursday with a modestly increasing pressure
gradient ahead of the boundary. For now, will show winds staying
below SCA thresholds, generally ~15 kt in the rivers, sound,
and bay with 15-20 kt offshore. Guidance does show the potential
for seas to build to 4-5 ft in SW flow late Wednesday into
early Thursday for our northern coastal waters but NWPS tends to
over estimate seas in SW flow. The cold front is forecast to
settle southward on Thursday but likely stalls somewhere near
the VA/NC border. The front resumes southward movement on Friday
with winds becoming NE ~10 kt behind the boundary.

Low rip current risk today and Tuesday at all area beaches.

&&

.CLIMATE...
Record Highs and record high mins may be challenged Mon-Wed.

- Record Highs:

- Site: Mon 7/15    Tue 7/16    Wed 7/17

- RIC:  100 (1995)  101 (1980)  100 (1980)
- ORF:  101 (1995)  102 (1879)  100 (1887)
- SBY:  100 (1995)   99 (1915)   99 (2012)
- ECG:   97 (1997)   98 (1995)   99 (1942)

- Record High Mins:

- Site: Mon 7/15    Tue 7/16    Wed 7/17

- RIC:   77 (1993)   77 (1983)   76 (2005)
- ORF:   82 (1992)   80 (1995)   80 (2021)
- SBY:   79 (1995)   78 (2013)   80 (1983)
- ECG:   78 (1993)   79 (2012)   80 (2019)

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...Heat Advisory from 10 AM this morning to 8 PM EDT this evening
     for MDZ021>024.
NC...Heat Advisory from 10 AM this morning to 8 PM EDT this evening
     for NCZ012-102.
     Excessive Heat Warning from 10 AM this morning to 8 PM EDT
     this evening for NCZ013>017-030>032.
VA...Heat Advisory from 10 AM this morning to 8 PM EDT this evening
     for VAZ064-065-075>090-092-093-099-100-511>525.
     Excessive Heat Warning from 10 AM this morning to 8 PM EDT
     this evening for VAZ095>098.
MARINE...None.

&&

$$

SYNOPSIS...LKB
NEAR TERM...LKB
SHORT TERM...LKB
LONG TERM...AJZ/LKB
AVIATION...ERI/LKB
MARINE...RHR
CLIMATE...