Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/19/24
AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
951 PM EST Thu Jan 18 2024
.SYNOPSIS...
High pressure slides offshore tonight ahead of an approaching
low pressure system. this area of low pressure impacts the area
Friday, bringing light snow to northern portions of the area,
with a mix of rain and snow for central portions, and mostly
rain elsewhere. A very cold airmass moves in Friday night
through the weekend. A moderating trend in temperatures is
expected early next week.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 925 PM EST Thursday...
Early evening analysis shows 1028+mb sfc high pressure offshore
with weak low pressure lifting across W KY/TN this evening.
Clouds have thickened and lowered as expected, and while some
virga is noted on regional radar mosaic, Td Depressions of
15-20+ degrees (C) demonstrate the antecedent dry airmass in
place over the local area. Temperatures were mainly in the lower
30s north, mid to upper 30s central and south and lower 40s SE,
as dewpoints remain in the 20s to low 30s.
No major change in forecast rationale for the incoming system.
The trough over the mid/upper Missouri Valley rapidly dives ESE
into the Ohio Valley overnight. The initial surface low to the
west weakens as it approaches the central Appalachians late
tonight, with secondary low pressure developing off the NC Outer
Banks. Some guidance depicts some light snow arriving into the
NW Piedmont late this evening prior to 06z/1AM. Otherwise,
mainly dry and cloudy this evening. Light precipitation likely
expands across most of the area after 09z/4AM. Thermal profiles
largely support snow from central VA to the interior of the MD
Eastern Shore (and bufkit profiles do show some decent ice
super- saturation in the cloud- layer just not deep moisture),
bordered by a rain/snow (briefly sleet) area from the SW
Piedmont toward the Tri-cities and the coast of the MD Eastern
Shore. P-type in this area will mainly be dependent on
intensity, with lighter precip supporting rain, and somewhat
heavier supporting snow. All rain is expected farther SE. The
best forcing shifts toward the Northern Neck and MD Eastern
Shore through the morning and afternoon as low pressure
organizes offshore. Meanwhile, a mid- level dry slot punches in
from the WSW quickly ending steady precipitation across the SW
half of the area. Most guidance depicts steep mid- level lapse
rates by afternoon as the upper trough pushes into the area.
This could result in a few rain and/or snow showers during the
afternoon (especially from the I-95 corridor to the coast.
12z/18 guidance has generally trended toward more snow across
the north (although the HRRR remains rather dry with limited
snow). Ensemble probs for >1" for a 10:1 SLR have increased
again to 50-80% across the far N/NE, and the EPS even has a
stripe of 30-50% across the RIC metro for Friday morning. A
winter weather advisory has been issued for the far northern
tier of the area, highlighting up to 1" of snow possible for the
morning commute, and locally up to 2". If the probs increase
for the RIC metro in the morning an expansion may be necessary.
Another area that could need an expansion would be the rest of
the MD Eastern Shore, which could have snow linger longer into
the afternoon. However, given the variability in the model
guidance over the past few days the low-end could verify with
little to no accumulation. Temperatures Friday will likely hold
in the lower to mid 30s where snow falls, and then ranging to
the 40s for the SE. QPF is limited overall, and generally less
than 0.25".
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 400 PM EST Thursday...
Partly cloudy and much colder Friday night into Saturday with
the shot of strong CAA behind Friday`s system. The sky will
average partly cloudy (potentially mostly cloudy near the coast)
with breezy NW winds (gusts to 25-35 mph expected). A few
flurries are also possible Saturday as a secondary shortwave
drops through the region with steep mid-level lapse rates. Highs
only in the lower-mid 30s after starting off in the upper teens
to lower 20s in the morning (with AM wind chill values
averaging 5-15F). A stronger shot of CAA arrives from the NW
Saturday-Saturday night, and Sunday morning will be the coldest
morning of the period as strong (1040mb+) high pressure builds
just to our west. Forecast lows are in the teens (with lower 20s
across far SE portions of the FA). The wind will remain
elevated, especially closer the coast. As a result, wind chill
values will be in the single digits area-wide, with a couple
hours of below zero wind chills possible across the far NW. Dry
and cold wx continues on Sunday as the strong high builds across
the local area with less wind expected as a result. Forecast
highs are in the 30s, after morning lows in the mid teens to
lower 20s.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 400 PM EST Thursday...
Dry/cold Sunday night with lows in the teens to lower 20s,
followed by highs moderating into the 40s Monday. High pressure
slides offshore Monday night into Tuesday with a moderating
trend commencing. Lows Monday night will still be seasonally
cool (in the mid 20s to lower 30s), with highs moderating into
the 50s Tuesday. Clouds will likely increase Tuesday due to WAA
aloft. Milder Tuesday night with lows in the mid 30s to lower
40s, followed by highs in the lower 50s N to around 60F S
Wednesday/Thursday. Minimal PoPs for light rain arrive Wednesday
into Thursday as southerly flow increases with weakening low
pressure approaching from the W and the arctic high well
offshore.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
As of 920 PM EST Thursday...
1025+mb high pressure is centered off the Carolina coast as of
18z. VFR conditions across area terminals prevail through the
overnight hours, with Sub-VFR conditions developing after
08-10z Fri Morning as low pressure approaches from the W-SW.
This area of low pressure tracks across the region Friday
morning, with secondary low pressure developing off the Carolina
coast and tracking NE. This will potentially bring a period of
snow to RIC late tonight through early Friday morning that could
end as a rain/snow mix before ending later Friday morning. A
longer period of snow is possible at SBY early Friday morning
into the afternoon. Farther SE, mainly intermittent areas of
light rain are expected Friday morning. IFR conditions are
possible from RIC to SBY with the period of snow or rain/snow.
Outside of SBY, drier air and VFR conditions arrive during the
afternoon with a W to WNW wind of 10-15kt gusting to 20kt, and a
few flurries/sprinkles are also possible with SCT- BKN SC.
Dry and VFR conditions prevail Friday night through Monday as
high pressure builds into the region. Breezy conditions in a NW
wind are expected Friday night into Saturday (with SCT-BKN CU
Saturday) as high pressure builds into the region. Increasing
clouds are expected by Tuesday as high pressure moves offshore.
&&
.MARINE...
As of 950 PM EST Thursday...
Small Craft Advisories are now in effect for the tidal rivers
beginning tomorrow afternoon through Saturday. The remainder of
the forecast remains on track.
Previous Discussion: Afternoon analysis shows 1022mb high
pressure moving off the NC coast ahead of weak low pressure over
northern FL. Aloft, flow is largely zonal/W-SW with a trough
over central Canada. Winds locally are from the SSW 10-15 kt
with waves around 1 foot and seas 1-2 ft.
Benign marine conditions persist tonight with winds becoming SW
then W and decreasing to 5-10 kt. The previously referenced
weak low over northern FL will slowly deepen and move NE up the
coast to near Cape Hatteras by Friday morning. The pressure
gradient will tighten considerably between this low and strong
(1040mb+) high pressure building in from the central CONUS
Friday afternoon and especially overnight into Saturday. Winds
increase (from S to N) Friday into the evening, generally NW
25-30 kt with gusts to 35 kt for the coastal waters, Ches Bay,
and Currituck Sound (generally 20-25 with gusts to 30 kt for the
rivers). A few gusts could approach 40 kt Friday night over the
coastal waters/mouth of the bay. Opted to upgrade the previous
Gale Watches to Gale Warnings and added the Currituck Sound to
the Gale Warning as well.
Expect a period of lighter winds (generally 20-25 kt) during
the day on Saturday before another strong surge of cold
advection moves in Saturday night with a return to gale
conditions expected. Confidence in reaching gale thresholds in
the Currituck Sound is lower for this period but the rivers
could see slightly higher winds during this surge. Very cold air
will move into the region Saturday night with the potential for
freezing spray. With offshore winds through the event, seas
will not build as high as the forecast wind magnitudes would
suggest. Seas increase to 3-6 ft N and 4-7 ft S (lowest near
shore and highest well offshore) through the weekend before
slowly subsiding late Sunday. Waves in the bay increase to 3-5
ft Friday evening through early Sunday. Expect much improved
boating conditions late Sunday into early next week as high
pressure moves over the area.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...Winter Weather Advisory from 4 AM to 7 PM EST Friday for
MDZ021.
NC...None.
VA...Winter Weather Advisory from 4 AM to 4 PM EST Friday for
VAZ064-075-076-517-519-521-522.
Winter Weather Advisory from 4 AM to 1 PM EST Friday for
VAZ509>511.
MARINE...Gale Warning from 7 PM Friday to 7 AM EST Sunday for
ANZ630>632-634-650-652-654-656-658.
Gale Warning from 7 PM Friday to 7 AM EST Saturday for ANZ633.
Small Craft Advisory from 4 PM Friday to 7 AM EST Sunday for
ANZ635>637.
Small Craft Advisory from 1 PM Friday to 7 AM EST Sunday for
ANZ638.
&&
$$
SYNOPSIS...AJZ/ERI
NEAR TERM...AJZ
SHORT TERM...AJZ/ERI
LONG TERM...AJZ/ERI
AVIATION...AJZ
MARINE...AJB/RHR
Area Forecast Discussion
National Weather Service Boston/Norton MA
954 PM EST Thu Jan 18 2024
.SYNOPSIS...
Other than scattered flurries, cold temperatures along with mostly
cloudy conditions is expected tonight into Friday morning. Weak low
low pressure area has the potential to bring accumulating light snow
to southeast Massachusetts Friday afternoon and evening, especially
from coastal Plymouth county to Cape Cod and the Islands. Lesser
snow accumulations expected north and west of Interstate 95. Frigid
temperatures to start the weekend give way to a warming trend
early next week. Above normal temperatures to return by mid week
along with the potential for some mixed wintry precipitation
type events.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
945 PM Update:
Temps in southeast MA have been running a fwe degrees warmer
than prior expectations due to westerly winds around 10 mph.
Used the latest HRRR temps to warm these up a bit trhough about
2 AM to mesh with current obs and expected near term trends.
Winds have already lightened in the interior and expecting winds
to ease in southeast MA overnight. Will remain OVC for the
balance of the night but with dry weather.
Previous discussion:
Isolated snow shower along leading edge of the LLJ continue to
wane at this time but may persist for another hour or two across
central CT and the Islands. Elsewhere, it remains a dry night.
A blanket of clouds is keeping temperatures relatively stable,
compared to last night, in the mid 20s to low 30s; the exception
being across northern MA where more scattered cloud conditions
have allowed temps to dip into the low 20s. Elected to not touch
the temperatures this evening as, noted by the previous
forecaster, clouds should continue to thin north of the "Pike"
through early morning.
3:30 PM Update:
Tonight...
* Light snow/flurries across CT/RI and southeast MA this evening
* Cold temps continue tonight
Band of very light snow/flurries across CT into southwest RI as of 3
pm. This is on the nose of modest 850 mb jet, which slides eastward
from CT/RI into southeast MA late this afternoon and early evening.
At 3 pm, 4 mile vsby in light snow at HFD and 8 miles at WST. This
band will remain very weak, therefore not expecting much if any
accumulation or impact.
Otherwise, other than scattered flurries, dry weather prevails
tonight in response to cold/dry confluent flow. Chilly airmass with
dew pts in the single digits and teens. This combined with light
winds and perhaps some thinning of the clouds toward morning,
especially across northeast MA, blended in some of the colder
guidance. This yields lows overnight 15-20, 20-25 southeast of I-95.
WSW winds 10-20 mph this evening, shift to the north overnight at 5-
10 mph.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/...
330 PM update:
Friday/Friday evening...
* Trend towards lower snow totals
* 1-3" southeast MA, coating to an inch elsewhere
Strong s/wv approaches SNE from the southwest Fri. However, this
s/wv and its attending surface cyclone track SE of the 40N/70W
benchmark Friday evening. This is in response to a very strong
closed low near Newfoundland, shunting the deep layer moisture
southeast of SNE over the ocean. Hence, appears the dry air
currently over SNE wins out. This is evident on model soundings and
cross sections, indicating the column and boundary layer really
struggle to saturate Fri afternoon & evening. This also limits the
effects from OES and low level convergence from inverted trough. In
addition, both the NAM and GFS indicate very weak lift in the DGZ.
Therefore, we trended our snow forecast down to 1-3 inches over
southeast MA, including Cape Cod and the Islands. Elsewhere, a
coating to an inch expected with possibly a shutout over northern MA
given depth and magnitude of dry air. Another red flag for
accumulating snow, is when blending all model guidance pops, likely
pops are limited to southeast MA. The caveat to this forecast is if
models are off with RH and blyr is able to saturate, then isolated 4-
5" are possible across coastal Plymouth county to the upper Cape
from OES and convergence from inverted trough. Not expecting any
impacts to the morning commute, as accumulating snow will be focused
to Fri afternoon and evening.
Friday night...
Drying out with clearing conditions overnight, but turning blustery
and frigid behind the departing arctic wave. Lows 10-15 but 5-10
above inland, but colder wind chills of zero to minus 10 across the
interior, zero to 10 above elsewhere.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
330 PM update...
Residual north/northeast flow will allow snow shower activity to
persist through about the midnight hour across southern Plymouth
county and the upper Cape before winds shift to the NW behind the
departing low. Given any light snow showers will be battling
incoming dry air, not much additional accumulation is expected after
sunset.
The greater concern for Friday night will be CAA as strong mid level
trough digs south of the region late Friday evening. High pressure
will lag a bit, meaning that the boundary layer will remain pretty
well mixed overnight, with wind gusts between 10-20kt. 925/850mb
begin their tumble to -12/-14C and -15/-17C, respectfully, which
will support lows dropping into the single digits and low teens by
sunrise Saturday. Anticipating, as lows will be driven by CAA rather
than radiation, that even our urban centers drop well into the 10s.
Wind chills will drop below zero for a good portion of the interior,
and while they will fail to meet "advisory" or "warning" level
criteria, residents of southern New England should take precautions
if they need to spend a prolonged period of time outside. Cold
airmass peaks Saturday as high pressure blossoms. Saturday will be
an especially frigid day with locations along and north of the I-95
corridor failing to reach 20F!Low temperatures Saturday night will
be similar to those observed Friday night. Overall, the message
remains consistent in that this is the coldest air we`ve seen since
last winter!
Mid level trough kicks out to sea by Sunday morning as mid level
ridging builds in behind it. While it will be warmer for much of
next week, there are questions surrounding just how warm we get as
we remain pinned between a shortwave to our northeast and the
surface ridge building in from the mid west. For now, expecting
temperatures above normal for a good portion of next week.
With that said, complex temperature profiles may yield some mixed
precip "overrunning" events in which southern New England could see
anything from rain to freezing rain to snow on Wednesday and again
on Friday. Guidance remains split on the potential, timing, and
coverage of systems next week, but several global models, including
the GFS and Canadian, indicate there may be something to watch in
the Tuesday night to Wednesday night timeframe.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
00Z TAF Update:
After 00z: high confidence.
VFR with marginal MVFR/VFR cloud bases after 05z. Other than a
few flurries possible this evening, dry weather prevails. WSW
winds 10-20 kt decreasing and shift to the NNW toward Friday
morning.
Friday: Moderate confidence.
VFR/MVFR with greater coverage of MVFR across CT/RI and
southeast MA. Uncertainty in how far north the MVFR cigs extend
but new guidance suggests they will make their way into Boston
and Worcester. Dry in the morning, then light snow developing
in the afternoon, highest probability from coastal Plymouth to
Cape Cod and the Islands. Light north wind in the morning
becomes NNE in the afternoon, increasing 10-20 kt.
Friday night: moderate confidence.
VFR except MVFR from Plymouth county to Cape Cod and the
Islands, in mainly light snow. Snow accumulations 1-3 inches
possible across coastal Plymouth to Cape Cod and the Islands. A
coating to 1 inch elsewhere. North wind 10-20 kt shifting to NW.
KBOS TAF...High confidence in TAF. VFR thru Friday night with a
period of light snow Friday afternoon and evening; a brief
period of MVFR is possible between 18-00Z as denoted as a TEMPO
in the forecast. Snow accumulations only a coating to 1 inch
possible.
KBDL TAF...High confidence in TAF. Marginal MVFR/VFR cigs thru
Friday evening, with a period of light snow Friday afternoon and
evening. Snow accumulations a coating to inch, with a low
probability of up to two inches.
Outlook /Saturday Night through Monday/...
Saturday through Saturday Night: VFR. Windy with local gusts up
to 30 kt.
Sunday: VFR. Windy with gusts up to 35 kt.
Sunday Night: VFR. Windy with areas of gusts up to 35 kt.
Monday: VFR. Breezy.
Monday Night: VFR. Windy with gusts up to 30 kt.
Tuesday: VFR. Breezy. Slight chance RA, slight chance SN.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
330 PM update...high confidence thru Fri night.
* Light to moderate freezing spray likely Fri night and into the
weekend
Tonight...
Weak high pressure briefly builds across the waters with WSW winds
10-20 kt becoming north overnight 5-10 kt. Other than scattered
flurries, dry weather and good vsby prevail.
Friday...
Low pressure off the VA coast races northeast, passing south of
40N/70W Friday afternoon, then out sea. Light north winds Fri
morning become NE and increase to 15-25 kt late in the day. Light
snow lowers vsby.
Friday night...
Low pressure rapidly intensifies as it tracks southeast of Nova
Scotia, yielding NNW winds 15-25 kt across the MA/RI waters. Light
to moderate freezing spray is likely. Light snow over the eastern MA
waters Fri evening moves offshore overnight.
Outlook /Saturday Night through Monday/...
Saturday: Winds less than 25 kt. Seas up to 5 ft. Chance of
freezing spray.
Saturday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft. Chance of freezing spray,
slight chance of snow.
Sunday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of seas approaching 5 ft. Chance of freezing
spray.
Sunday Night through Monday: Low risk for Small Craft Advisory
winds with gusts up to 25 kt. Seas locally approaching 5 ft.
Monday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Seas up to 5 ft.
Tuesday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas locally approaching 5 ft. Slight chance of rain.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 11 PM EST this evening for
ANZ254>256.
&&
$$
SYNOPSIS...Nocera/KS
NEAR TERM...Loconto/Nocera/KS
SHORT TERM...Nocera
LONG TERM...KS
AVIATION...Loconto/Nocera/KS
MARINE...Loconto/Nocera/KS
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1026 PM EST Thu Jan 18 2024
.SYNOPSIS...
A low pressure system arrives from the west tonight and crosses the
region, bringing a wintry mix to the mountains tonight and Friday.
Very cold air comes into the area behind the system and settles over
the region through the weekend. Warmer temperatures return early
next week.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 1000 PM: Band of rainfall now seen on radar mosaic from
eastern KY to NE AL, within warm advection preceding a shallow
shortwave and cold front. Echoes have a convective look over
the I-75 corridor of E TN, and FZRA or FZDZ have recently been
reported on ASOS and mPING obs from that area. If that isn`t
sufficient proof of a warm nose, recent RAP soundings reveal a
fairly stout one, and one ACARS sounding from Knoxville backs
that up. Meanwhile within the CWA, sfc temps have proven warmer
than almost all guidance, perhaps as low clouds moved in a little
earlier than expected. Dewpoints have rebounded but depressions
still are 25-35 degrees in many spots. It thus may come as no
surprise that recent hi-res models have largely come in drier
east of the mountains tonight. Likely to categorical PoPs remain
in the forecast for the mountains, but values in the Piedmont
are 5-10% lower. Temps eventually will wet-bulb down but still
think mins were too cold in these areas. Confidence in an all-rain
forecast remains high for areas near and southeast of I-85. Sfc
temps look to be the biggest impact on p-type tonight overall,
and especially in the Piedmont these should remain above freezing
thru the precip. It appears rain may mix with sleet as it tapers
off in the NW NC Piedmont, but this is not expected to be more
than a novelty, having little to no impact. For the mountains,
the changes were a little more notable. QPF came down a bit per
the hi-res models early on, and more of the QPF went into freezing
rain instead of sleet/snow. Thus, ice accum went up a little bit,
and snow down. These changes were not enough to warrant change
to the Winter Wx Advisory extents. Over the mtns, there should be
some pockets of sub-freezing air to support ice accum, but still
the amts will NOT be enough to reach warning criteria ice accum
in all likelihood. The first round of precip moves out quickly by
daybreak Friday outside of the wrn side of the mtns.
By sunrise Friday, we quickly pivot to a W/NW flow of low level
residual moisture getting forced up the west slopes by cold NW
wind. Temps fall steadily thru the day as the colder air moves
in behind the system, thus any remaining precip from this point
onward should be snow showers. Mid/upper forcing is relatively
weak as a following vort looks channelled. However, the upslope
flow looks good as the 850 flow becomes more NW into Friday
afternoon. Guidance suggests the Great Lakes connection will miss
to our N higher up the mtn chain in WV/VA. However, the moisture
should extend well up into the dendritic growth zone and the column
is so relatively cold that snow-to-luquid ratio climbs up into the
realm of 20-to-1 by late in the day. The upshot is that any snow
showers will probably be quite efficient at making a coating of
light/fluffy stellar dendrites. Most of the accumulation will be
close to the TN border, but some will spill outward away from the TN
border. The fcst snow amount has increased over the high terrain,
but not to the point where we are ready to bump up to a warning
or split any of the higher terrain off to its own Warning. This
could change with later fcst packages if the duration of the NW
flow snow production goes far enough into Sunday.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 120 PM EST Thursday: Broad cyclonic flow aloft will continue
to churn overhead as a stout Arctic High (1040+mb) slides down
the leeside of the Rockies. Stout CAA will continue to filter
in as the pressure gradient tightens across the mountains as
the leading edge of the high pushes into the region. With very
cold air settling in the wake of the near-term system to go
along with gusty winds, expect wind chill advisory values across
the mountains Friday night, with overnight lows expected to be
15-20 degrees below-normal. Ongoing NWFS will continue along the
NC/TN border, especially in the northern mountains. Low-level
moisture will become more shallow from Friday night to Saturday,
but lingering light snow showers will last into Saturday night
and even Sunday morning as northwest flow will be maintained by
the Arctic High. The Arctic High will be in control through the
weekend as temperatures in the CFWA will struggle to get out of
the 30s, while the mountains and I-40 corridor struggle to get
above freezing for highs Saturday afternoon despite mostly sunny
skies. Winds will gradually subside as the pressure gradient relaxes
and the center of the Arctic high settles over the TN/OH Valley
Saturday night. As a result, good radiational cooling conditions
will be in store and expect temperatures to run 15-20 degrees
below-normal once again for most locations. Needless to say,
it won`t take much wind to support wind chill advisory criteria
across the mountains, and possibly the NC foothills for Saturday
night. The cyclonic flow aloft will be disrupted by an emerging
upper ridge that will allow for the trough axis of the cyclonic
flow to finally push east of the CFWA by Sunday morning. Heights
will recover as the ridge builds in from the west and the Arctic
High will reside over the central/southern Appalachians by the end
of the period. Expect a slight rebound in temperatures on Sunday
as a result, with highs still ~10 degrees below-normal.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 235 PM EST Thursday: Last real cold night will be Sunday
night as good radiational cooling conditions remain in place as
overnight lows remain ~10 degrees below-normal with the Arctic
High in place. The airmass will modify considerably next week as
upper ridging amplifies over the region in response to a digging
upper trough over the western CONUS. The former Arctic High will
reside just offshore the North Carolina Coast and gradually bring
in a nice moisture flux into the southeastern CONUS. Timing and
uncertainty in QPF response still makes this a low confidence
forecast, but the general consensus is that temperatures will be
well above-normal by the middle part of the week with an active
pattern in place. Thus, expect rounds of good rainfall starting
some time during Tuesday and sticking around through the end of
the forecast period, possibly beyond.
&&
.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere: At issuance time low VFR clouds were
impinging on KAVL and KAND, with other sites to follow before
06z. Deeper moisture remains upstream nearer main shortwave, and
will eventually bring cigs near if not below the MVFR threshold
along with a chance for light precip near cold fropa. Per high-res
models timing is similar to 18z TAFs, if not slightly later. With
relatively rapid moistening evident upstream, confidence on
precip impacts is a little better, so TEMPO was warranted at all
sites. Moistening will occur from the top down, and restrictions
become possible with any precip, lingering at the SC sites and
KCLT until post-frontal downslope winds can erode cigs near or
after daybreak. Regarding precip type, KAVL and KHKY will be
slightly colder during the precip and stand the best chance of
a wintry mix overnight, although confidence is only high enough
to mention at KAVL. Developing NW flow at KAVL in the morning may
result in changes between MVFR and low VFR cigs thru the remainder
of the period; a few flurries could be seen but accumulating snow
not expected and thus no mention in TAF. Winds will remain SW`ly
and fairly light but flip to NW and gust once front passes in the
morning. By afternoon mixing, gusts above 25 KT are likely at KCLT
and above 30 at KAVL.
Outlook: NW Flow moisture will continue to bank along the TN/NC
border and produce -SHSN there into Friday night, with flurries
perhaps seen at KAVL at times. Very cold and dry VFR conditions
return for the weekend and last into early next week.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...Winter Weather Advisory until 7 AM EST Friday for GAZ010.
NC...Winter Weather Advisory until 7 AM EST Friday for NCZ053-059-
062>065-501-503-505.
Winter Weather Advisory until 7 AM EST Saturday for NCZ033-
048>052-058.
SC...None.
&&
$$
SYNOPSIS...CP
NEAR TERM...PM/Wimberley
SHORT TERM...CAC
LONG TERM...CAC
AVIATION...Wimberley
Area Forecast Discussion
National Weather Service Houston/Galveston TX
537 PM CST Thu Jan 18 2024
...New AVIATION...
.SHORT TERM...
(This evening through Friday Night)
Issued at 326 PM CST Thu Jan 18 2024
A dry cold front is expected to push across SE Texas tonight through
early Friday morning. Ahead of this front, winds are expected to
become light and variable with clear/mostly clear skies overhead.
Forecast soundings show a strong nocturnal inversion forming early
this evening, with ample moisture trapped beneath it. This will lead
to patchy/areas of fog developing tonight, mainly in areas along and
south of the I-10 corridor. These locations will be most at risk for
getting dense fog. Recent HRRR runs have trended slower with the
FROPA, increasing the fog potential and expanding it further north.
Thankfully, this fog should clear out during the early morning hours
of Friday as cooler/drier air filters in and breezier conditions
develop in the wake of the FROPA. Based on current guidance, the
fog should be over prior to sunrise (inland), so it should
(hopefully) not impact the Friday morning commute.
Friday will feature typical post-frontal conditions during the
daytime hours: Cool, dry, with clear skies and slightly breezy
conditions. Highs will top out in the 40s/50s during the day. Friday
night/Saturday morning will see sub-freezing temperatures return to
SE Texas with lows progged for the 20s/30s. Therefore, a Hard Freeze
watch will be in effect from 9 PM Friday Through 9 AM Saturday.
Depending on how conditions trend, Hard Freeze Warnings/Wind Chill
Advisories could be warranted during this period. Make sure to take
precautions to protect pets, plants and pipes from these frigid
conditions.
03
&&
.LONG TERM...
(Saturday through next Wednesday)
Issued at 326 PM CST Thu Jan 18 2024
The weekend will start out chilly and dry as we attempt to warm-up
after a very cold Friday night with surface high pressure overhead.
High temperatures on Saturday will get into the mid to upper 40s for
most of the area with overnight lows Saturday night in the mid to
upper 30s along and south of I-10, and then upper 20s to low 30s
northwards. Temperatures will only continue to rise through the rest
of the long term, and our next sub-freezing night won`t be for
awhile.
The surface high pressure slides to the east on Sunday inducing a
southeasterly flow at the surface ushering in moist, warmer
conditions into SE Texas. Meanwhile, a large upper level trough will
begin to set up across the Desert Southwest. Numerous shortwaves
will traverse the outside edge of this trough passing through SE
Texas. This parade of disturbance will each bring chances of
rainfall. The first of these disturbances is looking to be a rather
potent one and begins is pass through late Sunday into Monday.
Showers will begin to move into SE Texas from the southwest as early
as sunset Sunday, and then only increase in coverage and intensity
through Monday. Thanks to that SE flow, PWATs surge to near 1.5" on
Monday providing ample fuel to support showers and isolated
thunderstorms on Monday. Rainfall potential Sunday into Monday will
be generally up to 1-2", but locally higher amounts are likely. WPC
has placed the region in a Slight Risk of Excessive Rainfall (level
2 of 4) on Monday due to this rainfall. At this point, minor urban
or small stream flooding looks to be the main concern, but will
continue to monitor.
The train of disturbances continue through midweek bringing periods
of increased coverage and intensity of rainfall. An additional 1 to
2 inches or more of rain will be possible Tuesday and again on
Wednesday. Additional rainfall is possible after Wednesday, but
forecast confidence decreases.
Temperatures through the long term will see gradual warming. High
temperatures on Sunday will be in the 40s to 50s, then 60s on
Monday, and near 70 Tuesday and Wednesday. Overnight lows will see a
similar trend with lows in the 50s to low 60s by Monday night (quite
the difference a week makes).
Fowler
&&
.AVIATION...
(00Z TAF Issuance)
Issued at 537 PM CST Thu Jan 18 2024
SW winds beginning to settle down, all but Galveston is finally in
VFR, and weather should be fair...for a little bit. Front on pace
to sweep through the area late tonight, shifting winds northerly
at CLL around 05Z, reaching the coast shortly before dawn. Until
then, fog may briefly crop up for a few hours until the front
scours it out. I go as far north as IAH with some MVFR fog, but
the most impact will be farther south - have TEMPO IFR (or worse)
from HOU/SGR coastward. Once the front is through all fog will be
gone, but replaced by strong N winds, 15ish knots with gusts 25-30
knots for much of the day.
&&
.MARINE...
Issued at 326 PM CST Thu Jan 18 2024
There will be a window of potential fog this evening into early
tonight as moist air moves over the cool Gulf waters. Patchy, but
potentially dense, fog will be possible. The fog potential will end
after the passage of a cold front tonight ushering in moderate to
strong offshore flow. Northerly winds of 15 to 25kt with gusts to
30kts will be possible Friday morning through Friday night, and
these winds will also cause rough bay waters and build seas to 7 to
10ft. Small Craft Advisories are in effect for the Bays Friday
morning into Friday afternoon, and then for the Gulf waters into
Friday night. Winds may remain elevated for the eastern portions of
our Gulf waters beyond that requiring additional advisories into
Saturday afternoon - but at the very least, small craft will need to
exercise caution.
There will be the potential for some patchy fog returning Saturday
evening before onshore flow becomes too strong and dissipates the
fog. The onshore flow will strengthen Sunday and additional Small
Craft Advisories will likely be needed with onshore flow continuing
into Monday. The onshore flow will likely also bring slightly
elevated tides as well beginning on Monday. There will multiple days
of showers and thunderstorms possible next week starting as early as
Sunday afternoon and continuing through at least midweek bringing
locally heavy rainfall.
Fowler
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 34 45 23 44 / 0 0 0 0
Houston (IAH) 40 51 26 48 / 0 0 0 0
Galveston (GLS) 46 53 33 47 / 0 0 0 0
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Hard Freeze Watch from Friday evening through Saturday morning
for TXZ163-164-176>179-195>200-210>212.
GM...Small Craft Advisory from 5 AM to noon CST Friday for GMZ330-335.
Small Craft Advisory from 5 AM Friday to midnight CST Friday
night for GMZ350-355-370-375.
&&
$$
SHORT TERM...03
LONG TERM....Fowler
AVIATION...Luchs
MARINE...Fowler
Area Forecast Discussion
National Weather Service Wichita KS
536 PM CST Thu Jan 18 2024
...UPDATED FORECAST AND AVIATION DISCUSSIONS...
.KEY MESSAGES...
* Strong cold front arrives this afternoon/evening with Arctic air
returning
* A light snow and flurries possible through the evening hours
* Bitterly cold wind chills Friday and Saturday mornings
* Warming trend next week with additional precipitation chances
Monday and again Tuesday night through Thursday
&&
.UPDATE...
Issued at 511 PM CST Thu Jan 18 2024
Conditions have deteriorated across portions of northern and
central Kansas this evening. 40 to 60 mph winds behind a
powerful arctic cold front have caused areas of blowing snow
which have reduced visibilities in areas and created slick road
conditions with portions of Interstate 70 closed as a result.
These strong winds are expected to persist through at least 8PM
tonight before winds gradually decrease. Meanwhile, an intense
band of snow is moving southward out of Nebraska with very heavy
snow, strong winds, and visibilities below a quarter-mile at
times. Looking at mesoanalysis across northern Kansas, a
transient area of steep low level lapse rates, good boundary-
layer RH, and mid-level frontogenesis, will continue to support
this band of snow as it progresses southward. However, recent
trends suggest that this band may be weakening slightly. If it
continues to maintain itself on it`s current track, portions of
Lincoln and Saline counties may experience a brief period of
heavy snow with low visibilities. The more likely scenario is a
broad area of light snow or flurries with under a half inch of
snow accumulation.
&&
.DISCUSSION...
Issued at 130 PM CST Thu Jan 18 2024
As of 130pm Thursday afternoon, a wide range of temperature were
present across the central US as a strong cold front progresses
southeastward. At this hour, temperatures in the NE panhandle were
in the single digits and teens with 30s and 40s ahead of the front
in all of KS. As this front, progresses into the forecast area later
this afternoon into the evening, temperatures will tumble into the
single digits and teens by midnight and near-zero across central KS
by sunrise. Coupling in northerly winds gusting upwards of 35 mph
will contribute to wind chill values as low as -20 with the coldest
along I-70. A Wind Chill Advisory remains in effect for areas
along/north of Highway 50. In addition to the arrival of bitter air,
an area of light snow and flurries have developed across northern KS
and portions of NE within a broad zone of ascent in the left exit
region of a 500mb jet. This zone will pivot through portions of
central and east-central KS through the afternoon and evening
hours. Short range RAP and HRRR forecast soundings suggest the
overlap of moisture and ascent will occur for an hour or so at
any given location. Therefore, think any accumulation will be
very minor, if any at all.
Transitioning into Friday night, surface ridging will slide into the
area, plunging temperatures below zero across central KS with single
digits else. Wind speeds will be much lighter when compared to
tonight with the surface ridge overhead, yielding wind speeds around
5 mph. Even with lighter wind speeds, wind chill values will range
from 0 to -20 with the coldest along I-70 once again. A Wind Chill
Advisory remains in effect for areas generally north of Highway 400
Saturday morning.
The surface ridge will slide east of the area Saturday afternoon,
allowing southerly low-level flow to resume. Temperatures will
return to the 30s/near 40 Sunday afternoon. A weak, shortwave is
progged to eject into the central Plains Monday, bringing
precipitation chances to the area with the best chances southeast of
the Turnpike. At this point, thermal profiles appear to be warm
enough for a mostly rain event, although forecast trends need
to be monitored for the potential for a brief period of freezing
rain Monday morning. Stay tuned.
The warming trend will continue into mid-week with highs approaching
50 across southern KS Tuesday and Wednesday. Another shortwave
trough is progged to overspread the region late Tuesday into
Thursday, increasing rain chances area-wide.
&&
.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 515 PM CST Thu Jan 18 2024
Several significant aviation concerns are expected across
central Kansas over the next 6 hours.
The powerful cold front has arrived across and quickly
progressing across the area. In it`s wake, portions of central
Kansas, including sites KRSL, KSLN, and KGBD may experience
northerly wind gusts around 35 to 55 knots with areas of
blowing snow reducing visibilities under 1 mile at times. Areas
of light snow are also possible, mainly near KSLN over the next
6 hours.
As mentioned previously, the arctic front that is pushing
southward is also creating gusty northerly winds which will
quickly overspread the area. Wind gusts are expected to remain
within the range of 30 to 45 knots, but higher wind gusts are
possible over the next 12 to 18 hours. MVFR to IFR cigs are also
expected over the next 6 to 12 hours at all TAF sites.
After 12Z Friday morning, conditions will gradually improve area
wide as low cigs exit the area, and winds gradually decrease.
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
Wind Chill Advisory from midnight tonight to 10 AM CST Friday
for KSZ032-033-047>053-067-068.
Wind Chill Advisory from midnight Friday night to 11 AM CST
Saturday for KSZ032-033-047>053-067>072.
&&
$$
UPDATE...
DISCUSSION...BMB
AVIATION...JC
Area Forecast Discussion
National Weather Service Portland OR
353 PM PST Thu Jan 18 2024
.SYNOPSIS...Freezing rain impacts for the western Columbia River
Gorge into portions of the Portland/Vancouver Metro, in
addition to snow over the higher Cascades/Hood River Valley,
will be on the decrease tonight into Friday morning as
moderation for at least the Portland area finally occurs, albeit
slowly. Going forward, an active pattern keeps weather
disturbances moving into the Pacific Northwest Saturday through
the middle of need week with continued high mountain snowfall
and low elevation rain. However, the Hood River Valley remains
the exception and area of highest uncertainty at least through
Sunday morning as cold air struggles to be scoured out east of
the Cascade crest- line. All in all, most of the region finally
experiences a return to status-quo.
.SHORT TERM...TONIGHT THROUGH SUNDAY...Radar imagery continues
to show widespread precipitation across western Oregon and
southwest Washington late this afternoon as a warm-frontal
boundary lists through the Pacific Northwest. This feature in
conjunction with a weak upper-level ridge of high pressure off
to our east has strengthened the easterly surface pressure
gradient across the Cascades allowing the cold air trapped east
of the Cascades to filter westward through the Columbia River
Gorge into portions of the Portland/Vancouver Metro area. While
high resolution models like the HRRR and HREF have captured the
overall theme of freezing rain chances increasing for the
eastern Portland/Vancouver metro, they’ve struggled to resolve
the finer details of the cold air advection near the surface
today as it fights against a warmer airmass moving in from the
south. Current surface observations, traffic cameras, and
spotter reports indicate the worst ice accumulation today has
been in the Gorge through Troutdale, Gresham, and Happy Valley.
While models suggest temperatures drop another degree or two in
the Portland/Vancouver metro this evening, helping to extend the
areal coverage of freezing rain impacts briefly, precipitation
noticeably lightens the second half of the night as we enter the
warm sector behind the frontal boundary. Past this point
temperatures slowly moderate and any lingering intermittent
precipitation remains light. It’ll be a similar story for the
evolution of snowfall impacts in the Hood River Valley and
higher Cascade locations as well. The current winter weather
highlights for freezing rain and/or snow in the north Oregon
Coast Range, Portland/Vancouver Metro, Columbia Gorge, Hood
River Valley, and Cascades of Washington have been maintained
into Friday morning. Overall the rest of the Friday through
Friday night stays rather quiet with slight chances to
chances(15-40%) for light precipitation over primarily the Coast
Range, Willapa Hills, and Cascades. Confidence is high even for
the terrain features mentioned QPF amounts totals below
0.25-0.5” through this Friday through Friday night period.
On Saturday guidance is in good agreement resolving the overall
weather pattern as a weakening closed low off the coast of
northern California swings northward brushing western Oregon
before moving into Vancouver Island Saturday evening.
Precipitation likely increases region-wide as a result from
south to north during the late morning and afternoon hours
accompanied by snow levels around 5500 to 6000ft so the mainline
Cascade passes likely just see rain – all rain for the
Willamette Valley and Portland/Vancouver metro area as well.
That said, it still appears the track of this disturbance
facilitates continued offshore flow and an increase in the
easterly pressure gradient across the Cascades from the surface
to at least 850mb, which given the remnants of the arctic
airmass still trapped east of the Cascades would suggest wintry
precipitation chances for the Hood River Valley and
central/eastern Columbia Gorge. The latest deterministic models
soundings from the GFS and NAM still lend confidence to this
with freezing rain and/or ice pellets favored as warmer air
increases aloft east of the Cascade crests Saturday night. But,
cold air at the surface in this set-up is often troublesome to
scour out with models typically over-mixing the boundary layer
suggesting to quicker moderation than what actually occurs. The
forecast was adjusted to better match this scenario through
Saturday into Sunday morning as which point 850mb winds finally
turn westerly and moderation may finally occur on Sunday. Still,
it remains to be seen whether this will be enough to completely
moderate the Hood-river Valley since winds at the surface area
still have an offshore component. With all the recent wintry
precipitation down to the valley floor and these higher snow
levels by Saturday/Sunday onward we`ll have to keep an eye on
area rivers as well. Many are expected to see decent rises over
the weekend into early next week peaking around action
stage/bankfull. -Schuldt
.LONG TERM...MONDAY THROUGH THURSDAY...Monday into Wednesday
deterministic and ensemble guidance both begin to hint at at
least a little uncertainty in the progression of the upper-level
disturbances however the larger scale pattern favors persistent
WSW flow. With this in mind, snow levels likely remain near to
above pass level with continued bouts of lower elevation
rainfall, although rainfall amounts through this period don’t
appear abnormal for this time of year. From Monday night through
Wednesday night as at least another two weather disturbances
race through the Pacific Northwest, the latest NBM projects a 50
to 80% chance for the coast range and Cascade to meet or exceed
2 inches of rain with probabilities near zero for the
Willamette Valley and SW Washington and the Willamette Valley.
Come Thursday some ensemble guidance suggest a building ridge of
high pressure arriving into the Pacific Northwest however
struggle with the amplification and longitudinal placement of
this feature – not too surprising out at day 7 to day 8.
-Schuldt
&&
.AVIATION...Conditions vary considerably across the area with a
warm front competing with cold low level offshore flow from east
of the Cascades. This will result in varying conditions through
the through tonight. The overall trend is for the pcpn to taper
off from south to north as the upper portion of the system moves
north of the area. But with cold air near the surface, temperature
inversion could bring MVFR to IFR conditions overnight.
Rain for all, except freezing rain for the PDX area, and freezing
rain, snow in the Gorge through this evening (details in the PDX
section below.)
PDX AND APPROACHES...Cold easterly winds from the Gorge continue
this afternoon and tonight. Freezing rain persists at KTTD area
and is expected to expand west to KPDX later this afternoon. As
mentioned above pcpn expected to end or at least taper off after
07Z Fri. Icing issues become increasing likely at KPDX after 00Z
Fri with ice accumulation around 0.10 inches currently forecast.
&&
.MARINE...Warm front will lift northward across the region today,
with the trailing cold front approaching the waters Fri. Gale
Warning continues today and tonight for the outer waters with
Small Craft Advisories for the inner waters. Another system nears
the waters Friday, but pressure gradients not quite as potent, and
seem to be favoring more east to southeast flow. More systems
follow over the weekend but will appear to be weaker than the
current system.
Seas remain in the 10 to 15 ft range through will be quite choppy
with forecasted winds next few days. /mh
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 10 AM PST Friday for Coast Range
of Northwest Oregon-Greater Portland Metro Area-Lower
Columbia.
Winter Storm Warning until 4 AM PST Friday for Central Columbia
River Gorge-Upper Hood River Valley.
Ice Storm Warning until 10 AM PST Friday for Western Columbia
River Gorge.
WA...Winter Weather Advisory until 10 AM PST Friday for Greater
Vancouver Area.
Winter Storm Warning until 4 AM PST Friday for Central Columbia
River Gorge-South Washington Cascades.
Ice Storm Warning until 10 AM PST Friday for Western Columbia
River Gorge.
PZ...Small Craft Advisory until 7 AM PST Friday for Coastal waters
from Cape Shoalwater WA to Florence OR out 10 NM-Columbia
River Bar.
Gale Warning until 7 AM PST Friday for Coastal waters from Cape
Shoalwater WA to Florence OR from 10 to 60 NM.
&&
$$
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