Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/16/24
Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
133 PM AKDT Tue Oct 15 2024
.SYNOPSIS...
Widespread snow expected across the North Slope and Brooks Range
through Wednesday as a low moves east. The heaviest snow will
occur over the central and eastern Brooks Range, where 4 to 8
inches of snow are expected through Wednesday. Snow showers spread
southeast across the Interior tonight into Wednesday, with
accumulations of 1 to 3 inches expected. West to southwest winds
with gusts of 25 to 30 mph develop across the Interior Wednesday.
Along the eastern Beaufort Sea Coast, west winds to 40 mph
Thursday will produce areas of blowing snow, potentially dropping
visibility to one mile or less at times. High pressure and colder
temps settle in for the weekend over the Interior. A strong late
fall storm for the West Coast is looking more likely late this
weekend and early next week, with that front possibly bringing
widespread precipitation to the Interior into the early week.
&&
.DISCUSSION...
Aloft, at 500 mb, a 506 dam low is over the western Canadian
Archipelago with a trough axis extending south to Valdez. The
trough axis moves east of the AlCan border by Wednesday morning as
a 516 dam shortwave trough over the northeastern Chukchi Sea
drops quickly southeast across the North Slope to be near Nuiqsut.
The shortwave continues its southeast track with the trough axis
stretching from Nuiqsut to Stevens Village to Healy Wednesday
morning and well into the northern Northwest Territory by Thursday
morning. Meanwhile, upper level ridging builds across the Bering.
At the surface, a 980 mb low is near Prince Patrick Island. A 997
mb low is 100 NM north of Point Lay this afternoon with an
occluding front extending south to Kotzebue, south across the
Seward Peninsula and to near Hooper Bay. The low tracks east
southeastward to be 50 NM north of Kuparuk by Wednesday morning
and then moves east to near Mackenzie Bay Wednesday afternoon as a
998 mb low and weakens. The associated front weakens as it
marches east southeast across the Interior. On Thursday, a warm
front will push northeast across the Chukotsk Peninsula and into
the Chukchi. High pressure builds over the Bering through Friday.
Models...
The 15/12Z model suite initialized well aloft and at the surface.
Models are in good agreement with overall synoptic pattern
through the next several days. Models continue to handle the low
moving across the North Slope well and the associated front well.
Overall, the inherited grid package looks to be in good shape and
is on track. As such, made only minimal changes to the forecast to
account for ongoing precip trends and winds. Continued the trend
of favoring the NAMNest for winds, HRRR for increasing wind gusts
across the Interior with the cold air advection, and the AKSREF
and NBM for pops and snow amounts.
North Slope and Brooks Range...
Widespread snow showers spread east across the North Slope and
Brooks Range through Wednesday as the low and associated front
push east. The heaviest snow will occur over the central and
eastern Brooks Range, where 4 to 8 inches of snow are expected
today through Wednesday. In the favored upslope areas of the
Brooks Range, locally higher snow amounts are possible. Along the
coast, snow amounts will be lower, in the 1 to 3 inch range. Snow
showers are expected to persist through Thursday along the central
and eastern Beaufort Sea coast, dropping an additional 1 to 2
inches of snow. In addition to the snow, strong westerly to
northwest winds to near gale force develop across the western and
northwest Arctic Coast this afternoon and persist through much of
tonight, diminishing early Wednesday morning. Elevated water
levels of around 2 feet above the normal high tide line are
expected from Point Hope to Point Lay tonight into early Wednesday
with the main hazard being rough surf along the coast and some
possible minor erosion. On Thursday, strong westerly winds to 40
mph develop over the eastern Beaufort Sea Coast, producing areas
of blowing snow, potentially reducing visibility to one mile or
less at times.
West Coast and Western Interior...
As a low pushes east across the North Slope and Brooks Range,
widespread snow showers will shift east southeast from Kivalina
and the Noatak Valley to the south slopes of the Western Brooks
Range and the Upper Kobuk Valleys this evening and tonight.
Scattered snow showers spread southeast to the Western Alaska
Range tonight through Wednesday morning. Snow amounts will range
from 2 to 4 inches across the south slopes Western Brooks Range,
to 1 to 2 inches over the northwestern Interior to the northern
Seward Peninsula, and up to an inch over the southern Interior
through Thursday. From the southern Seward Peninsula to the Y-K
Delta, a mix of snow and rain can be expected. Gusty northwest
winds of 25 to 35 mph develop north of the Seward Peninsula this
afternoon and evening, diminishing by Wednesday morning. Elevated
water levels of around 2 feet above the normal high tide line are
expected from Kotzebue Sound to Point Hope tonight into early
Wednesday with the main hazard being rough surf along the coast
and some possible minor erosion. Colder and drier high pressure
settles in Thursday night.
Central and Eastern Interior...
Light snow persists over the southern and eastern Interior this
afternoon, with only light accumulations expected. A front pushing
southeast across the Interior tonight and Wednesday will bring
another round of snow showers and gusty west to southwest winds.
Strong cold air advection behind the front will result in wind
gusts of 25 to 30 mph. Snow accumulations generally in the 1 to 3
inch range, with higher elevations seeing locally higher amounts.
Drier and colder conditions expected Thursday as cold air moves
in, with temperatures.
Extended Forecast Days 4-7...Friday and Saturday are drying out
over most of the Mainland as arctic high pressure settles in, with
the coldest temps of the year by far. Lows by this weekend may be
pushing into the single digit range Friday and through the
weekend for overnight lows across the Interior. A weak low may
clip the West Coast on Saturday with some flurries/light snow
showers, but that is inconsequential compared to the powerful
front which is looking more likely Sunday evening and into early
next week. Currently it looks fairly likely that a strong front
with south winds will impact the coast, and may bring coastal
impacts as the low moves inland Monday. That same front may bring
in heavy precip all the way through the Interior, which may fall
as mixed precip, or all snow. Bottom line, the projected storm may
bring a myriad of impacts to Alaska, so stay tuned to future
forecasts.
Coastal Hazard Potential Days 3 and 4...None.
&&
.AFG WATCHES/WARNINGS/ADVISORIES...
AK...None.
PK...Small Craft Advisory for PKZ806.
Small Craft Advisory for PKZ807.
Small Craft Advisory for PKZ808.
Small Craft Advisory for PKZ809-855.
Small Craft Advisory for PKZ810-856.
Gale Warning for PKZ811-812.
Small Craft Advisory for PKZ813.
Small Craft Advisory for PKZ814-860.
Small Craft Advisory for PKZ815-861.
Small Craft Advisory for PKZ817-854.
Gale Warning for PKZ857-858.
Small Craft Advisory for PKZ859.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
732 PM EDT Tue Oct 15 2024
.KEY MESSAGES...
- Rain showers will end from west to east through this evening.
- Dry Wednesday through Friday with temperatures climbing well
above normal.
&&
.SHORT TERM /THROUGH TONIGHT/...
Issued at 330 PM EDT Tue Oct 15 2024
Our CWA`s first measurable snowfall observation was this morning at
the cooperative observer 3mi WNW of Michigamme; a few additional
trace snow observations were also seen in northwestern MI.
RAP analysis this afternoon shows an elongated trough extending back
from eastern Quebec into the lower Great Lakes, noting a shortwave
that has dropped south across the UP today. At the sfc, 1034mb high
pressure has become situated over MN with the 993mb sfc low
northeast of ME. This sets up cool northerly flow with 850mb temps
of -4C to -6C descending across Lake Superior. With the lake sfc
around 12C to 13C, northerly lake effect showers/sct cloud cover has
decorated the satellite imagery and lit up the radar mosaic,
particularly over the east where there is more convergence, the
coldest airmass, and a longer fetch. As the high pressure continues
to settle south and the mid level ridging builds in from the west,
these showers will dry out from west to east through late this
evening with gradually clearing skies this evening through tonight.
Not much of any additional accumulation beyond a few hundreths is
expected. Northerly winds gusting into the 20mph range over the east
and in the Keweenaw this afternoon begin to tapper off into this
evening. Otherwise, temps the rest of the afternoon will maintain in
the upper 30s to mid 40s.
Skies gradually clearing out with a drier airmass moving in from the
west (PWATs lowering to 0.25" to 0.3") is indicative of good
radiative cooling. The interior should see lows in the 20s to low
30s, warmer in the east where cloud cover lingers on longer. The
lakeshores will drop into the 30s to low 40s, but a few upper 20s
cant be ruled out where there is better clearing. If skies in the
east clear out earlier tonight, the minimum temp forecast may not be
low enough. Typical low lying cool spots in the west may dip below
20F ahead of sunrise.
&&
.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
Issued at 439 PM EDT Tue Oct 15 2024
The extended period will start out with a shift in the pattern as
high-amplitude ridging overspreads much of the central CONUS on
Wednesday. The ridge axis will then move overhead on Thursday,
resulting in a period of dry conditions for Upper Michigan through
mid-week. Meanwhile, a warming trend will accompany the ridge,
pushing temperatures above normal for the duration of the period.
These factors combined with a tight pressure gradient (strong winds)
could elevate the fire threat for Thursday and Friday until the next
chance for some rain showers arrives over the weekend. Any
rainfall amounts will be negligible, though, Saturday through
Monday with the best chances not arriving until Tuesday when a
more defined shortwave drifts through Ontario.
As mentioned above, the southwesterly surface flow will bump daytime
highs back into the 50s on Wednesday. And, highs will then just
slowly increase into the low to mid 60s on Thursday and eventually
upper 60s/low 70s from Friday through Monday. Long range ensemble
guidance then trends back toward a slow decrease by Tuesday with
highs falling back into the low to mid 60s. Concurrently, overnight
lows will generally be in the 40s through this time frame. They
will, however, start out a bit chilly Wednesday night until the
pattern change. Look for overnight lows in the upper 20s to mid 30s
across the interior that night (warmer near the lakeshores).
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 731 PM EDT Tue Oct 15 2024
Expect VFR conditions for the remainder of the TAF period as high
pressure ushers in drier air across Lake Superior the UP, tapering
off lake effect clouds from west to east overnight into Wednesday.
Clouds will hang on to SAW the longest, scattering out by sunrise.
Winds back west-southwest tomorrow with gusts highest at CMX upwards
of 20-25 kts possible in the afternoon.
&&
.MARINE...
Issued at 357 PM EDT Tue Oct 15 2024
Northerly winds will gust to 25 to 30 kt through late evening along
with a waterspout threat along the south shoreline. At that point,
though, winds will weaken to below 20 kt tonight as they back to the
northwest. Wednesday, winds will shift to the southwest, increasing
to 25 to 30 kt once again over the west half of the lake. Thursday
through Friday, winds will become more south-southwesterly at 25 to
30 kt across the entire lake. Saturday, winds will diminish below
20 kt but remain southwesterly as a cold front approaches the area.
Sunday, southwesterly winds will continue, but expect an uptick to
20 to 25 kt across central portions of the lake during the
afternoon.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Jablonski
LONG TERM...TDUD
AVIATION...BW
MARINE...TDUD
Area Forecast Discussion
National Weather Service Riverton WY
947 PM MDT Tue Oct 15 2024
.KEY MESSAGES...
- Warm and dry conditions remain for today and tomorrow with
gusty winds developing tomorrow afternoon as a disturbance
moves into the region.
- A much welcomed shift in the weather pattern is expected to
occur for the second half of the week.
- A potent low is expected to bring widespread precipitation and
colder temperatures for the second half of the week into the
weekend.
&&
.DISCUSSION...
Issued at 206 PM MDT Tue Oct 15 2024
The change in the weather pattern that most if not all of the Cowboy
State has been waiting for looks to be on its way. However, we must
first deal with another few days of warm above normal temperatures,
mainly dry conditions, and gusty winds. Temperatures today are
expected to remain in the low to mid 70s across the CWA. Winds will
remain light with dry conditions. Wildfire smoke continues to linger
across central and western basins which may reduce visibility at
times.
Wednesday will see highs nearly 15 to 20 degrees above normal with
increasing winds as a strong trough moves into the PACNW. High
temperatures are forecast to be in the upper 70s to low 80s east of
the Divide. West of the Divide will see warm temperatures as well
but only in the low 70s. As mentioned earlier, winds are expected to
increase Wednesday with widespread southwesterly winds of 15 to 25
mph with gusts of 30 to 40 mph possible at times. The warm
temperatures and gusty winds will create near critical fire weather
conditions but RH values are looking to be above criteria and the
limiting factor. However, it is worth keeping in mind how warm and
dry it has been over the past couple of weeks. This dryness combined
with gusty winds will likely mean there may be some concern
regarding fire weather conditions but at this time no fire related
highlights will be issued. As the trough moves farther east during
the day Wednesday there is the chance for some scattered showers and
thunderstorms to develop across the southwestern CWA. Due to the
dryness of the atmosphere most of these showers will be virga. Winds
will remain gusty through the overnight hours Wednesday into
Thursday as the trough moves closer to the area.
A drastic shift in the weather pattern arrives Thursday as a second
strong trough rapidly barrels across the PACNW. A cold front will
begin to sweep across the state starting late Wednesday into early
Thursday morning. This will lead to cooling 700mb temperatures with
snow levels over western WY dropping through the night and morning
Thursday. The front looks to stall across northern/western parts of
the CWA, leading to strong gusty winds over the Wind Corridor
throughout Thursday. There will be chances for precipitation
throughout the day Thursday with the best chances being in areas
west of the Divide. Precipitation does look to gradually spread
eastward as the aforementioned second trough moves into the region.
The second trough will be the main weather maker for our area as it
quickly digs south into the Great Basin by Thursday night. A potent
low is expected to develop as a result of this, which will keep
precipitation over the CWA due to moisture being funneled northward.
The stalled front will begin to move southward during the late hours
Thursday into the early morning hours Friday. This front will be a
key aspect of the forecast as its ability to cool temperatures down
will be a crucial factor in determining whether or not low
elevations east of the Divide see a period of wet snow Friday.
Models currently show a 30-60% chance of seeing precipitation in the
form of wet snow or mixing during the day Friday for areas east of
the Divide. 700mb temperatures support this as temperatures range
from minus 5 to minus 9 over this area. Another factor will be
precipitation rate, as the heavier precipitation falls the greater
chance of cooling occurring throughout the atmosphere, possibly
leading to precipitation transitioning to snow. Friday morning
through the early afternoon looks to see the heaviest precipitation
as winds will be supportive of upsloping mainly across the eastern
slopes of the Wind River and Big Horn Ranges. Temperatures will be
well below normal Friday with highs likely occurring during the early
morning hours before sunrise. The current forecasted temperatures
during the day Friday range from the low to upper 30s with values in
the mid 40s in the far eastern and northeastern portions of the CWA.
So overall, what can be expected with this upcoming system? Starting
with high elevations, precipitation will likely fall mainly as snow
with a brief period of rain possible ahead of the front late
Wednesday into Thursday. The greatest snowfall is likely to remain
above 8,000 feet with the highest peaks seeing the most. Eastern
slopes of the Wind River and Big Horn Ranges will see the most
snowfall due to favorable upsloping occurring Friday. Due to this
Winter Storm Watches have been issued for these ranges to account
for storm total amounts near or exceeding 12 inches in some
locations. Hunters who plan to head into the higher elevations
should take notice of the chance for heavy snowfall at times along
with cold temperatures especially overnight Friday into Saturday
morning. Low elevations will likely see precipitation mainly in the
form of a very cool rain with chances for some mixing or full
transition to heavy wet snow at times. Thankfully precipitation is
looking to be fairly widespread with nearly everyone seeing some
much needed moisture. The highest amounts look to be across the
southern and central portions of the CWA with higher amounts
possible along the eastern slopes of the Wind River and Big Horn
Ranges. There is a good chance of seeing a transition over to a mix
of rain/snow or fully to heavy wet snow during the morning Friday
possibly into the afternoon. This is due to cooling temperatures
behind the front and the timing of the heaviest precipitation which
may aid in keeping temperatures from warming all that much. Overall,
low elevations will likely see a cool rain to start with the
possibility of a transition to a mix or heavy wet snow. However,
even if there was to be a transition to snow, accumulation will be
very minimal and mainly be restricted to grassy surfaces. The system
gradually comes to an end by Friday evening with cold below normal
temperatures expected to move in as clouds clear overnight. Some of
the coldest temperatures so far this season are forecast for
Saturday morning with values in the upper 10s to mid 20s across the
CWA.
&&
.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 945 PM MDT Tue Oct 15 2024
Light winds and a mainly clear sky (outside any wildfire smoke)
prevails overnight and into Wednesday morning. An approaching
weather system brings stronger southwest winds ahead of a cold
front. These winds pick up Wednesday morning. Gusts 20 to 30 knots
will be common amongst the sites, with KCPR and KRKS seeing the
strongest winds in their favored southwest flow.
Precipitation will come with this weather system, but the best
chances aren`t until after the TAF period. However, models are
indicating the potential for some leading moisture to bring light
rain showers, or virga showers, for southwest sites (KBPI, KPNA,
KRKS) between roughly 22Z and the end of the period. Confidence
remains low (20% to 30%) as of now on if these showers would produce
any impactful rainfall. Have kept mention out of those TAFs for now,
but have lower increasing clouds towards the end of the period.
Smoke at KJAC is tricky. The increased southwest flow Wednesday may
keep most smoke out of the valley. The latest HRRR agrees with this
assessment. Have kept smoke through the overnight hours, though have
VFR visibilities. Some thin smoke may continue during the day
Wednesday, with little impact. Will continue to monitor trends to
see if this persists for the next TAF issuance.
Please see the Aviation Weather Center and/or CWSU ZDV and ZLC
for the latest information on smoke, icing, and turbulence
forecasts.
&&
.RIW WATCHES/WARNINGS/ADVISORIES...
Air Quality Alert until 1 PM MDT Wednesday for WYZ005-007-
016>019.
Winter Storm Watch from Thursday morning through Friday
afternoon for WYZ008-009.
Winter Storm Watch from late Wednesday night through Friday
afternoon for WYZ014-015.
&&
$$
DISCUSSION...Dziewaltowski
AVIATION...Wittmann