Chesapeake, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

683
FXUS61 KAKQ 180849
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
349 AM EST Sat Jan 18 2025

.SYNOPSIS...
Milder temperatures and scattered showers are expected today.
Another low pressure system will bring a chance for rain and
snow to the area on Sunday. Much colder weather is expected by
early next week. A low pressure system could also bring
accumulating snow to portions of the area later Tuesday into
Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 330 AM EST Saturday...

Key Messages:

- A few showers are expected today, although coverage will be quite
spotty.

- Mild temperatures (for mid January) this afternoon once the rain
departs.

Morning sfc analysis shows high pressure moving further offshore,
while low pressure deepens over the southern Hudson Bay. A cold
front extends S from the low through the Great Lakes and Midwest
states into the MO Ozark region. Aloft, water vapor imagery depicts
a compact shortwave trough moving into the TN/KY region, while a
strong 250 mb jet is situated over the Deep South on the srn
periphery of the larger longwave trough. Locally this morning,
there are increasing high-level clouds across our CWA ahead of
these features. Temps are chilly in the upper 20s to lower 30s,
but these values are "milder" than the previous few nights due
to the clouds and a light southerly wind.

That shortwave will advance into the Carolinas this afternoon,
kicking off low pressure formation offshore of the NC OBX.
Meanwhile, weak isentropic ascent overspreads the area later this
morning into the early afternoon as the (weakening) front approaches
from the W. Overall, not expecting much in the way of widespread
rainfall today. In fact, every new run of the CAMs seem less excited
about much in the way of any rainfall. However, still expect a few
showers to move into our wrn counties after sunrise this morning,
while a few additional showers develop across the SE as the low
deepens and departs offshore. PoPs in these areas are 30-50%
(highest coastal NE NC), while only 20% elsewhere. Additionally, the
departure of the rain has trended faster so there will likely be a
good deal of clearing this afternoon. This should allow for temps to
warm to above average levels by the middle and late afternoon,
with low-mid 50s for most of the area. A few upper 50s or even
60 F readings are possible across SE VA and NE NC, as suggested
by the MOS guidance and the HRRR. The one exception is across
the far NW where low-level cold air tends to be a tad more
stagnant. Here, forecast highs are only in the mid 40s. Mainly
dry overnight though clouds will again be on the increase. Lows
only drop into the mid-upper 30s inland and lower 40s across the
SE.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
As of 330 AM EST Saturday...

Key Messages:

- A light snow accumulation remains possible across the northern
tier Sunday.

- Quickly falling temperatures Sunday afternoon and night will be
the start of a very frigid airmass for next week.

As today`s shortwave swings offshore tonight, another sharper trough
will approach the area Sunday. Sfc low pressure is forecast to
develop near the NC Piedmont early Sunday, deepening as it moves NE
into our CWA in the afternoon, and then quickly into the New England
states by the evening. Very cold air (and strong cold advection)
will be push in behind the low and cold front, especially later in
the afternoon and evening. Still looking like rain initially Sunday
morning (w/ a rain/snow mix across the NW), transitioning to
rain/snow or snow through the afternoon as temps crash. There
remains some disagreement among guidance on the exact track of the
low, which dictates the placement of colder and warmer air. The
HRRR/RAP/RGEM are the warmest, which would suggest snow only during
the wrap-around period in the evening. The NAM/GFS and (to a lesser
extent) the ECMWF are cooler, suggesting a quicker changeover and
more snow across the northern tier. The overall trend has been
"warmer" and have inched up hourly temps a degree or two during the
day Sunday. This leads to lower snowfall accumulations and latest
forecast has about an inch from Louisa to northern Carolina counties,
with 0.5-1" to the S of this stripe, extending into Dorchester
County, MD. Only a light coating is expected from the RIC metro into
the Northern Neck and Eastern Shore. While a brief rain/snow mix or
snow changeover is possible further SE, no accumulation is expected
at this time. With the lower snowfall totals, Winter Weather
Advisories look unlikely at this point, though the forecast is still
subject to change over the next 24 hrs or so. Impacts should
generally be limited given the holiday weekend, but there could be
still some slick spots on the roads, especially overnight Sunday as
the crashing temps could freeze any leftover water or snow. Again,
temperatures fall quickly later in the day Sunday so high temps will
be achieved early in the day. These highs range from the mid-upper
30s across the N, with 40s and even lower 50s the further S one
goes. Very cold and blustery Sunday night with lows in the teens in
the Piedmont and lower 20s to the E. Wind chills likely will be in
the teens areawide, with single digits possible across the Piedmont,
Northern Neck, and MD Eastern Shore. While marginal, a Cold Weather
Advisory may be needed.

Behind Sunday`s arctic front, a very cold stretch is expected
through at least the middle of the week. Monday will be cold, but
dry/mostly sunny, with blustery conditions and wind chills in the
lower 20s and teens persisting through the day. Lows Monday night in
the single digits and teens. Areas with any lingering snowpack could
drop even colder. While winds should be lighter overnight Monday, a
light wind will still produce wind chill values in the single digits
and possibly just below zero on the MD Eastern Shore. Cold Weather
Advisories very likely will be needed for much of the area Monday
night into early Tuesday.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 330 AM EST Saturday...

Key Messages:

- Very cold temperatures expected through most of next week. Lows
could drop to near zero for portions of the area.

- Confidence on impactful, accumulating snow has increased some for
later Tuesday and Wednesday.

Very cold conditions continue into Tuesday and Wednesday with strong
Canadian high pressure N of the area and anomalous troughing aloft
over the much of central and eastern United States. High temps
Tuesday and Wednesday struggle to leave the 20s, with lower 20s or
even upper teens across the N. Overnight lows will remain in the
single digits and teens, with wind chills in the single digits and
possibly below zero for some areas. The need for Cold Weather
headlines continues during this time and there is a non-zero chance
for Extreme Cold Warnings in some areas. Preparations to protect
property and those vulnerable to the cold should be completed soon.

Now...the other aspect of the forecast is the potential for
accumulating snow Tuesday evening into Wednesday. Confidence has
increased in this potential, with southern and southeast portions of
the area most at risk at the moment. There is an impressive signal
for a southern stream disturbance to track through the southern US
Tuesday with an expansive precip shield extending from the Deep
South into Carolinas Tuesday night into Wednesday in the favorable
synoptic ascent region downstream of the parent shortwave. This
disturbance is also expected to eventually kick off low pressure
formation near the Southeast coast Tuesday night. Where this happens
(and how far N the low gets) will dictate how far inland precip can
reach. The exact upper-level evolution of the southern stream trough
and its interaction with its northern stream counterpart will
dictate the placement of these sfc features. With strong high
pressure to our N and plentiful cold air, it is very likely that
any precip will be snow (models have the 0 C 850 mb line
several hundred miles to our S). The strength of this high
should also prevent significant westward and northern
adjustments in the guidance with this system, but further
western (or eastern) adjustments are still possible.
Furthermore, the very cold temps favor high- ratio snow and
dynamic ratio algorithms support closer to a 15:1 SLR. Should
there be snow, there will also be some risk of blowing snow at
the coast given a compressed pressure gradient from the strong
high to our N and the low to the S.

All three 00z runs of the global deterministic models (GFS,
ECMWF, and CMC) trended further W compared to their 12z runs and
each shows warning-level snow across at least our southeastern
counties. However, it remains very important to stress that we are
still about 4 days out and a lot can change. The range of outcomes
across the GEFS/EPS/GEPS ensembles ranges from a major snowstorm to
zero snow with the system suppressed to our S. Still, probabilities
from these various ensemble suites and the NBM are quite impressive.
The EPS, GEPS, and NBM all have probabilities of 40-50% for >6" of
snow in NE NC and far SE VA, with 50-70% and 70-80% probs for >3"
and >1", respectively. There are even 10-25% probs for ~12". Note
that these probs are all based on 10:1 SLRs, so it is plausible that
these probs are actually a tad higher. The GEFS remains on the
lower side of the overall guidance envelope, so again this is
certainly not set in stone. Still well outside the Watch
timeframe (<48 hours), but these would need to be considered
over the coming days should the current trends hold. A first
stab at snowfall accumulations can be expected by this time
tomorrow (Sunday) and users are highly encouraged to stay
updated with the latest forecasts.

Beyond Wednesday, temps moderate some, but only into the 30s for
highs Thursday and teens for lows Thursday night. Also need to watch
for a potential coastal low late in the week. At this time,
confidence is very low, but did introduce 20-30% PoPs (highest
along the coast). Depending the track of the low and antecedent
temps, additional wintry wx could be possible. For now, highs
Friday are in the lower 40s.

&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
As of 1240 AM EST Saturday...

Prevailing VFR is expected at most terminals through the 06z
period. Winds will generally be 5-10 kt from S through the day
into early tonight. In terms of cloud cover,
increasing/thickening clouds are expected over the next few
hours, with BKN-OVC skies by sunrise. Weak low pressure still
looks to pass through the region on Saturday, bringing a chance
for light rain showers. However, coverage looks spotty at best
and am expecting little to no impact at any of the local
terminals. The chances of MVFR flight restrictions have lowered
and have removed mention of this from the TAFs. Will maintain a
PROB30 group at ECG for brief moderate showers, but this may
even be generous. Skies begins to clear from W to E later this
afternoon and evening before clouds increase again after 00-03z
Sunday.

Outlook: Another low pressure system is expected to deepen
across the Carolinas Saturday night, tracking ENE on Sunday.
Flight restrictions are more likely with this system,
potentially in the form of low CIGs/VSBYs before 12z Sunday,
and continuing with rain changing to snow during the day Sunday.
Snow probabilities will be highest NW of the main terminals
through at least midday Sunday, but will transition to the SE
late Sunday aftn into Sunday evening, with snow becoming more
likely at RIC/SBY, and possible at the SE VA/NE NC terminals
before ending Sunday evening. VFR, but with blustery NW winds
Sunday night through Monday. Remaining dry for most of Tuesday,
but a chance for snow returns late Tuesday through Wednesday (it
should be noted that confidence in this timeframe remains low
given a lot of uncertainty).

&&

.MARINE...
As of 330 AM EST Saturday...

Key Messages:

- Benign marine conditions are expected through Sunday morning.

- A strong cold front crosses the coast later Sunday afternoon with
a period of gale conditions possible Sunday evening through Sunday
night.

- Low pressure tracks off the Southeast coast Tuesday night into
Wednesday bringing the potential for another period of strong wind
and elevated seas.

High pressure is centered offshore early this morning, with low
pressure well SW of the region. The wind is mainly SSE 5-10kt south
to 10-15kt north. Seas range from ~2ft south to 2-3ft north, with 1-
2ft waves in the Ches. Bay. Benign marine conditions continue today
through Sunday morning. The wind will primarily be SSW 5-10kt today
and then become SW tonight. A compact area of low pressure does
develop off the southern Outer Banks today, but quickly tracks NE
away from the coast and has little impact on the local marine area.
Seas will be ~2ft south to 2-3ft N, with 1ft waves in the Ches. Bay
today and tonight.

By Sunday morning, low pressure develops over the western Carolinas
and tracks NE ahead of a strong cold front. The wind will initially
remain light, 5-10kt and shift to the NE across the northern tier of
the marine area, and S to SE across the southern tier of the area.
The cold front crosses the coast later Sunday aftn and early Sunday
evening. Strong CAA arrives in the wake of the front along with
sharp pressure rises of 5-7mb/3hr progged by the 00z/18 NAM and 6-
9mb/3hr from the 00z/18 GFS. Additionally, EPS probs for wind gusts
>= 34kt have increased to >50% for the Ches. Bay and ocean
(especially N of the VA/NC border). Given these factors, a gale
watch has been issued from late Sunday aftn through Sunday night for
the VA portion of the Ches. Bay and ocean N of the VA/NC border. The
current forecast for these locations is a NW wind of 25-30kt with
gusts to 35-40kt, with 15-25kt with gusts to ~30kt elsewhere. The
wind remains NW 15-20kt with gusts to ~25kt Monday into Monday
night, but does begin to diminish over the rivers and Currituck
Sound Monday night. Seas build to 4-6ft S to 5-7ft N Sunday night
into Monday with 3-4ft waves in the Ches. Bay.

High pressure nudges into the region Tuesday with the wind
diminishing and seas subsiding. Low pressure tracks off the
Southeast coast Tuesday night into Wednesday as strong high pressure
builds in from the NW. A more amplified trend developed during the
00z/18 model cycle. This would bring a potential for gale
conditions, especially S of Cape Charles, with SCA conditions likely
elsewhere. Freezing spray is likely during periods of strong wind
late Sunday night through the middle of next week as an arctic
airmass overspreads the coastal waters.

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...Gale Watch from Sunday afternoon through late Sunday night for
     ANZ630-631.
     Gale Watch from Sunday evening through late Sunday night for
     ANZ632-634-650-652-654-656.

&&

$$

SYNOPSIS...SW
NEAR TERM...SW
SHORT TERM...SW
LONG TERM...SW
AVIATION...SW
MARINE...AJZ