Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/08/21

Area Forecast Discussion

National Weather Service Caribou ME

 914 PM EST Sun Feb 7 2021

.SYNOPSIS...
Strengthening low pressure will track south and east of Nova
Scotia overnight. High pressure is expected to cross the region
on Monday. Another low will cross the region late Tuesday and
exit across the Maritimes early Wednesday. High pressure will
build across the region on Thursday with low pressure expected
to pass south of the area Friday.

&&

.NEAR TERM /THROUGH MONDAY/...
9:15 PM Update: A deep surface low is passing south of Nova
Scotia and will track to the east of the province overnight.
Snow has spread north to the Saint John Valley, but with only
trace amounts in Caribou and Madawaska as of 9 PM. Along the
coast there have been a couple of reports approaching 2", and it
is snowing moderately in Eastport by the looks of the web
cameras and with 1/2 mile visibility reported. The heaviest of
the snow has been more concentrated across the Bay of Fundy and
into parts of Nova Scotia. Looking at the satellite pictures and
radar trends it is looking increasingly likely that it will
be tough to get widespread warning criteria snowfall in the
warned areas. An inch an hour snow is still possible, especially
in Washington County for the next 4 or 5 hours, but it should
lighten up by 1 or 2 am in the morning. Will make some tweaks to
lower amounts by a couple of inches in the warned areas, but
with the storm ongoing and a number of 8-12" totals in areas
that were upstream in eastern MA will hold onto the current
warnings and advisories for now. The best chance of warning
criteria will be near Eastport with less of a chance in coastal
Hancock County.

Previous discussion:
Low pressure continues to bomb this afternoon as it tracks near
the benchmark and south of Nova Scotia later tonight. This is an
intense system that is producing heavy snowfall rates in eastern
Mass. The strong banding and mid-lvl FG will track towards
coastal Washington County this evening and produce snowfall
rates that may exceed 2 inches an hour late this evening for
locations such as Machias and Eastport. The heavier snowfall
rates will quickly exit the area after midnight. Will maintain
existing Winter Weather Warnings for the Downeast region
without any change, but did increase overall snow amounts for
coastal Washington County. Shorter term guidance such as the
HRRR and RAP are lining up well with the existing forecast and
the RAP has performed reasonably well so far this afternoon. The
intensifying surface low will quickly develop a compact closed
upper level circulation in the Gulf of Maine this evening as it
races northeastward. The Downeast area will also be on the
northern edge of the stronger winds with the low and some gusts
up to 35 mph can be expected tonight in combination with the
high snowfall rates. The winds resulted in a slight reduction in
our snow ratios Downeast. Added mention of blowing snow in that
area for tonight.

Further north of the Downeast region, the upper trough passage,
surface convergence and higher snow ratios will help net amounts
as high as 7 inches in the advisory area and amounts of 2 to 4
inches north of the advisory area.

In the aftermath of the storm, strong northwest winds and fluffy
snow will create some blowing snow issues in the farmland of
Aroostook County. Winds will be gusting to 30 mph. Cold air
advection will continue through the day as H850 temps drop
towards -20C. Monday high temps will be fairly close to early
morning readings.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
Mainly zonal flow wl be acrs the CWA Mon evng with high pressure at
the sfc building in fm the west and bisecting the state in the
morning. Hv significantly undercut guidance with min falling into
the negative teens acrs the north under moclr skies and near calm
winds. May still be too warm with temps.

Clds will be on the increase Tue aftn ahead of the next system. By
18z system wl be located in the vicinity of the NY Bight as it
begins to exit the eastern seaboard. Low pressure wl pass south of
the waters with a general light snow expected along Downeast areas
Tue afternoon into the evng. Guidance still rmns unclear on how much
influence inverted trof will have on area`s wx Tue evng. 12z NAM is
the outlier bringing the coastal low thru the Gulf btwn 00z-06z Wed
while GFS, CMC and GFS take it to the south of the waters and
eventually south of Nova Scotia. Inverted trof being indicated by
all guidance but EC seems to be overdone with qpf assoc with feature
while GFS/CMC seems to be more reasonable with only about 0.05"
falling with trof. Either way, still looks as tho another 2-4 inches
looks possible along the Downeast coast with around 1-2 inches rmndr
of the region, with the possible exception of the far northeast.

NW winds wl continue as the system departs on Wed with snow showers
likely continuing acrs the north thru the morning. High temps on Wed
wl rmn blo normal with highs in the teens acrs the north to m20s
over Downeast.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Zonal flow wl follow the system pretty much thru the end of the week
as elongated upr trof extends acrs Canada until 06z Fri. Upr low
fcst to drop into the upr Midwest Fri morning per operational GFS
and EC and their ensembles. As it does so, expect that s/wv wl
approach the region fm the southwest on Fri and overspread snow drg
the day. Temps thru the end of the weekend likely to rmn blo normal
as arctic air rmns acrs the region but nowhere near as cold as the
nrn Plains.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
NEAR TERM: IFR being reported at the northern and eastern Maine
terminals as of 9 PM. IFR tempo LIFR in snow through late
tonight. All terminals will be predominately VFR by late Monday
morning. Light wind at the northern terminals, with a north to
northeast wind of 10 to 15 knots at BHB and BGR. A NW wind will
increase to around 15 knots with gusts to 25 knots Monday and
will produce some blowing snow.

SHORT TERM:
Mon night...VFR. NW 5-10kts becoming light by morning.

Tue-Tue night...Becoming IFR in -sn Downeast in the afternoon,
MVFR/IFR terminals north of HUL in the evening. Light W Tue,
becoming S in the afternoon, and NNW late.

Wed...MVFR/IFR across the north in low cigs and blsn. Becoming
VFR in the afternoon over Downeast. NW 5-10kts and gusty.

Wed night-Fri...Mainly VFR. NW 5-10kts through Thu, light N Fri.

&&

.MARINE...
NEAR TERM: The wind is still a bit short of gales as of 9 PM,
but is continuing to ramp up with gusts to around 30 knots on
the outer waters. Gales are expected to develop late this
evening as an intense low pressure system moves well south of
the Gulf of Maine and south of Nova Scotia. The wind will
decrease slightly later tonight, but pick up again Monday
morning in the strong northerly flow following the low.

SHORT TERM: Winds will remain at SCA levels Mon evening before
diminishing around midnight. Brief wind gusts to nr 25kts on
the outer waters Wed evening. Wave heights will remain above 5ft
thru midnight Tue night and will likely be able to drop SCA by
that time.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory until 4 AM EST Monday for MEZ006-011-
     015-016-032.
     Winter Storm Warning until 4 AM EST Monday for MEZ017-029-030.
MARINE...Small Craft Advisory until 4 PM EST Monday for ANZ052.
     Gale Warning until 1 PM EST Monday for ANZ050-051.

&&

$$

Near Term...CB/MCW
Short Term...Farrar
Long Term...Farrar
Aviation...CB/MCW/Farrar
Marine...CB/MCW/Farrar



Area Forecast Discussion

National Weather Service Cheyenne WY

 839 PM MST Sun Feb 7 2021

.UPDATE...
Issued at 835 PM MST Sun Feb 7 2021

Seeing temperature at 2 degrees here at the office this evening,
Did an update to lower overnight lows east of the Laramie Range.
Updates have been sent.

UPDATE Issued at 502 PM MST Sun Feb 7 2021

Went ahead and cancelled the High Wind Warning for central
Laramie County. Front has moved into the area and winds have
shifted northeast. Elsewhere...winds are easing out by Rawlins and
Laramie as well as Saratoga...so allowed the warnings to expire
out there. Updates sent.

&&

.SHORT TERM...(Late this afternoon through Tuesday night)
Issued at 213 PM MST Sun Feb 7 2021

Scattered snow showers are expected to push through southcentral to
southeastern Wyoming into the western Nebraska Panhandle tonight.
There is still potential for blowing snow across Arlington/Elk
Mountain across I-80 along with strong wind gusts up to 65+ MPH
therefore both High Wind Warning and Winter Weather Advisory will
extend to 00Z Tuesday. Upper level winds continue to trend 60+kts
for the Laramie Range Foothills with strong gradients and a dominate
westerly flow will provide high confidence for an extension of the
High Wind Warning for that area until 00Z. Zone 118 including Cheyenne
will also continue under a High Warning until 11 PM MST with
current wind gusts obs gusting to 50-55 MPH.

Moderate snowfall up to 3 inches is possible starting 5 PM this
evening into 5 AM MST Monday for Scottsbluff County, Goshen
County, east Platte, and south Sioux counties including the cities
of Scottsbluff, Wheatland, Torrington, and Guernsey. Models such
as the NAMNest and HRRR hint at snowfall totals around 2-3 inches;
Additionally with the possibility of those driving across Highway
26 this evening into the late morning hours of Monday, confidence
is high thus leading to a Winter Weather Advisory.

Cold Temperatures will continue through Tuesday night. Wind chill
values are reaching the negative double digits in northwestern
Nebraska Panhandle and southcentral Wyoming. Skies will remain
overcast for most areas through Tuesday night.

.LONG TERM...(Wednesday through Sunday)
Issued at 230 PM MST Sun Feb 7 2021

Deep cyclonic flow aloft will be the dominant weather feature for
the long term. Broad polar vortex situated over central/southern
Canada will drift south and east across the northern/northeast
CONUS through the end of the week. Additional short wave energy
will dive southeast into the western and central CONUS next
weekend. The arctic front over eastern WY and southwest NE will
slowly progress south through southeast WY by the end of the week.
The majority of the models prog the coldest airmass to spread
across MT, the Dakotas and Upper Midwest, with 700mb temperatures
as low as -25 degrees Celsius along and east of the Laramie Range.
The EURO has been trending warmer than the other MOS guidance for
the past few days. The GFS has been consistently colder and
remains the model of choice. High temperatures will range from the
single digits to teens, with overnight lows falling to the single
digits above to teens below zero. There will be enough of a low
level pressure gradient to keep winds blustery at times resulting
in bitterly cold wind chills (as low as -35 degrees), especially
at night. Besides the unseasonably cold temperatures, there will
be chances for measurable snow each day, especially west of the
Laramie Range.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 434 PM MST Sun Feb 7 2021

IFR to LIFR CIGS expected to continue across the NE Panhandle this
evening and through around 12z as narrow band of snowfall across
the North Platte River Valley is reducing VIS below 2 miles at
area sites. Gusty high winds across WY will slowly decrease after
sundown though persistent gusts in excess of 25kt expected to
continue. Snow will eventually taper off for NE though CIGS will
remain low with fog development in the overnight.


&&

.FIRE WEATHER...
Issued at 253 PM MST Sun Feb 7 2021

No fire weather concerns in the near future due to incoming snow showers
and minimum RHs trending mostly above 40-50% for the next week. Wind gusts will
trend higher in the southeastern Wyoming than the Nebraska
Panhandle.

&&

.CYS WATCHES/WARNINGS/ADVISORIES...
WY...Winter Weather Advisory until 5 AM MST Monday for WYZ107-108.

     High Wind Warning until 5 PM MST Monday for WYZ110-116-117.

     Winter Weather Advisory until 5 PM MST Monday for WYZ110.

NE...Winter Weather Advisory until 5 AM MST Monday for NEZ019-096.

&&

$$

UPDATE...GCC
SHORT TERM...AW
LONG TERM...MAJ
AVIATION...WM
FIRE WEATHER...AW



AREA FORECAST DISCUSSION

National Weather Service Eureka CA

 248 PM PST Sun Feb 7 2021

.SYNOPSIS...High pressure aloft will continue to promote a period of
dry weather through the middle of next week with increasing
cloudiness. A cold front arriving late Thursday will bring rain and
high elevation snow into next weekend.

&&

.DISCUSSION...A broad trough of low pressure will continue across
much of the contiguous United States into early in the coming week
while a narrow but amplified ridge over the E Pacific dampens. Early
this morning, low clouds once again blanketed many interior river
valleys. In addition, northerly flow continued to bank cloudiness up
against the coastal terrain around Humboldt Bay, the Eel River Delta,
and N of Cape Mendocino. Much of this cloudiness again eroded by
late morning, with mostly sunny skies across the area this afternoon.
As of this writing, temperatures were mostly in the 50s, with 60s
found across Lake and inland Mendocino counties, along with a few
spots in Trinity and S Humboldt counties.

Low clouds are once again forecast to expand along portions of the
coast tonight. In addition, mid and high cloudiness will be on the
increase through the night ahead of an approaching weak disturbance.
Thick mid-level cloudiness will continue through the day, and this
may delay or prevent low clouds from going away as well due to the
lack of sunshine. The potential for light rain on Tuesday, which was
low to begin with, has decreased. However, clouds will linger through
the day, although there may be some breaks in the cloud cover from
time to time. Partly to mostly cloudy skies are expected for
Wednesday as the E Pacific high pressure ridge briefly amplifies.
Rain chances increase late in the week with better chances of rain
and high elevation snow. forecast precipitation amounts have come up
a bit with the latest model runs, with around an inch of rain
possible. Snow levels will start off over 6000 feet on Friday, but
levels will likely drop through the weekend, with snow levels below
4000 by Sunday. /SEC

&&

.AVIATION...Late morning satellite imagery showed more inland valley
fog than this time yesterday. HREF has potentially been over-
estimating the potential for downsloping drying at KACV, as the
Humboldt Bay stratus became more embedded early this morning than was
expected. Coastal stratus was pumping into the Eel River delta with
some back-filling through Humboldt bay, and up to the fringes of KACV
before eventually receding. Leaned to HRRR Vsby and RH product
through the 18Z TAFs, as it resolved a similar setup as was seen this
morning. That said, a weak coastal wind eddy should transport the
Humboldt bay stratus again late this evening around KACV. MVFR to
periods of IFR or lower CIGS in the early morning hours tomorrow are
anticipated to occur at KACV. HRRR hints of a summer-like southerly
eddy along the immediate coast to advect the stratus to KCEC after
midnight. Added a SCT layer, may need more stratus. A broad high
cloud deck will move in through the period and slowly lower through
mid-levels by tomorrow afternoon as the ridge flattens ahead of a
weak system. The lack of solar insolation, along with light winds may
delay the erosion of the coastal stratus tomorrow. Northerly winds
today will back off this evening, becoming light and variable at the
coastal terminals. KUKI will continue to see light to calm winds and
VFR conditions.

&&

.MARINE...Another afternoon of reinvigorated northerly winds is
underway over the waters, with a subsequent slight uptick in steep
seas after subsiding some last night. Inner water buoys are verifying
the Small Craft Advisory with steep 7 to 9 ft short period seas
early this afternoon. Extended SCA in outer waters. The ASCAT
scatterometer pass today had detailed coverage of our waters, and
revealed the accelerated expansion fan off Cape Mendocino to be
generating up to 30 kt sustained winds in an isolated area. Highly
confined gusts up to 34 kts and gale conditions lee and alongside the
cape will occur with these winds through the early evening. Bumped
up the winds a little today to match that area. HRRR seemed to
capture this slightly better than other high-res models today. Winds
and seas will begin a slow decline late tonight. Substantial
reductions in steep sea heights are forecast to occur Tuesday and
Wednesday when sustained speeds drop to 15 kts or less, along with
some small mid to longer period northwesterly swells. Considerable
forecast uncertainty crops up toward the latter portion of the week
as the models continue to portray a couple of systems plowing into a
dominant ridge and busting down a strong downstream block.

&&

.EKA WATCHES/WARNINGS/ADVISORIES...
CA...None.
NORTHWEST CALIFORNIA COASTAL WATERS...
     Small Craft Advisory until 3 AM Monday for PZZ450-455.
     Small Craft Advisory until 4 PM Monday for PZZ470-475.

$$

Visit us at https://www.weather.gov/eureka

Follow us on Facebook and Twitter at:
https://www.facebook.com/NWSEureka
https://www.twitter.com/NWSEureka

For forecast zone information
see the forecast zone map online:
https://www.weather.gov/images/eka/zonemap.png



AREA FORECAST DISCUSSION

National Weather Service Hastings NE

 745 PM CST Sun Feb 7 2021

...Short Term and Aviation Update...

.UPDATE...
Issued at 744 PM CST Sun Feb 7 2021

Regarding the remainder of the overnight hours:

- Decided to formally extend the inherited Winter Weather Advisory
  (which includes the vast majority of our Nebraska CWA) several
  more hours through 3 AM (was set to expire at 6 PM). Main
  motivation was two-fold:

1) With lingering light snow (at least flurries) continuing across
most of the area this evening, did not want to give the impression
that snow would "magically stop" at 6 PM, as much of the area will
likely receive at least an additional half-inch this evening-
overnight...just enough to "mess up" snow removal efforts and keep
some roads slick.

2) Some models (most notably 18Z NAM/NAMNest were concerningly-
aggressive developing a "sneaky" heavier snow band somewhere near
the I-80 corridor this evening-overnight. So far, this appears to
have been a bit over-done, as radar trends and latest HRRR are
starting to suggest the greatest potential for perhaps another
(roughly) inch of snow overnight will focus mainly within our
bottom two rows of Nebraska counties and clipping the state line
(mainly near/south of Highway 6 corridor).

So given above reasoning, felt it would be prudent to hang onto
the Advisory several more hours, while acknowledging here that at
least portions of it may ultimately end up being cancelled early
depending on trends. We normally don`t extend Advisories when
additional accumulations are only expected to average around
1-inch or less, but with all the snow we`ve piled up in the last
48 hours, 6 PM seemed a bit early to perhaps send an overly-
optimistic "all clear" impression. As for the currently-pegged
Advisory end-time of 09Z/3AM, this should at least get us passed
the "window of opportunity" for any possible enhanced narrow
banding. To be sure, pesky very light snow/flurries could continue
even beyond this into Monday morning, but barring a surprise,
doubt we`ll be able to truly justify yet another time extension by
that point.

Last but not least, and while definitely not the main reason for
the Advisory extension, have also continued highlighting within it
the likelihood of at least spotty overnight wind chills as cold as
-15 to -20 degrees. This would flirt with, but likely fall just
 short of enough areal coverage of -20 to justify the issuance of
 a formal Wind Chill Advisory.

&&

.DISCUSSION...(This evening through Sunday)
Issued at 143 PM CST Sun Feb 7 2021

The main concerns are:
1. Snow this afternoon and overnight
2. Cold through the forecast

Upper level northwesterly flow continues and unfortunately
disturbances continue to track southeastward along it bringing
additional chances for snow. The bulk of the disturbance that
brought another 3 to 5 inches has pushed off to the east. Winds
were a bit stronger than expected too, which has caused some
blowing and drifting. Another wave is moving southeast over north
central Nebraska. This could drop some more snow across
northeastern sections of the area.

High-resolution models have been identifying an area of
precipitation/snow developing from northeast Colorado into
southern Nebraska moving in with another weak disturbance. This
was a very consistent signal throughout the morning hours on most
high- res models. Thus with this and the potential for an
additional inch this afternoon into early evening, decided to push
the headline out for all counties through 00z. As of the 19z
there have been some echos developing on radar mosaic in this
area...giving some credence to those solutions. Now that being
said, what will this amount to and will it be later than
advertised this morning. Some of the 18z runs show this being a
bit later, centering on 00z vs. 21z and lingering into the
overnight hours. We always were expecting more snow tonight in a
lighter snowfall event. As mentioned in the update around
noon...if the stuff expected this afternoon/evening were by
itself, an advisory would definitely not be needed...but it is
like adding insult to injury at this point...especially for roads
crews. Another inch or so is possible for portions of south
central Nebraska...and cannot rule out isolated higher amounts as
well.

In addition the precip adjustments...did lower temps slightly
today and tonight. We are just not warming up. Since my arrival 7
hours, the temperature has had a range of less than 2 degrees.
There`s just no other way around it...it`s cold and it`s going to
remain cold...bitter cold.

Precipitation potential will diminish Monday, leading to some dry
periods...but cold will be here to stay. There will be a slight
moderation (weak use of the term) in temps for the
Tuesday/Wednesday as the upper pattern becomes slightly more
zonal and the waves. This weak moderation adjusts high temps
closer to 10 degrees vs. the single digits.

As the main disturbance over Canada begins to move mid-week it
will dislodge some bitter bitter cold air. Highs will again
plummet back in to the low single digits...maybe even struggle to
reach above zero at times. More important to impacts is the
bitter wind chill. Wind chill values will hang out in the 10 to 20
below zero most of the week, and towards the end of the week they
will drop into the 20 to 30 below zero territory which brings in
Wind Chill Advisories and potentially Wind Chill Warnings. Stay
tuned.

Additional snow continues to be a concern off and on as we move
from mid-week on. To early for any details on that.

&&

.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday)
Issued at 744 PM CST Sun Feb 7 2021

General overview:
High confidence in sub-VFR conditions throughout the period (save
for perhaps only a brief reprieve or two). The majority of the
time, the sub-VFR will be driven by either MVFR/IFR ceiling, with
the likelihood of IFR more favored during the latter half of the
period Monday daytime and MVFR more dominant the first half
(overnight). Visibility and precipitation-wise, especially these
first 6-9 hours will likely continue to feature pesky/light
lingering snow or flurries, with visibility mainly fluctuating
between MVFR/VFR depending on intensity. Although at least
lingering flurries certainly cannot be ruled out beyond 09Z, opted
not to officially include any -SN mention beyond this (but later
forecasts will need to re-evaluate). There are also hints of some
light freezing fog perhaps trying to develop at some point Monday
morning, so this will need monitored as well, but do not expect
anything too extensive given considerable cloud cover.

Winds:
Not much of an issue through the period, with sustained speeds
only averaging 5-10KT as direction prevails somewhere between
northeasterly and easterly.

&&

.GID WATCHES/WARNINGS/ADVISORIES...
NE...Winter Weather Advisory until 3 AM CST Monday for NEZ039>041-
     046>049-060>064-072>077-084>087.

KS...NONE.
&&

$$

UPDATE...Pfannkuch
DISCUSSION...Billings Wright
AVIATION...Pfannkuch



Area Forecast Discussion

National Weather Service Grand Rapids MI

 1002 PM EST Sun Feb 7 2021

LATEST UPDATE...
Update

.SYNOPSIS...
Issued at 223 PM EST Sun Feb 7 2021

- Cold and snowy pattern through next weekend

&&

.UPDATE...
Issued at 1001 PM EST Sun Feb 7 2021

No real changes from my previous update. The 00z model runs of the
RAP, HRRR, NAM, and NAMNEST still like the idea of a mesolow
developing Monday morning and moving on shore south of MKG. The
snow showers should start to increase over midnight west of
US-131.

I is already near to below zero over our NE CWA so I lowered the
lows some but I believe clouds will overtake all of our CWA
overnight so it should not get much colder than it already it.
Leota fell to -8F at 8:12pm but they have warmed to 0F already.



UPDATE Issued at 630 PM EST Sun Feb 7 2021

I have updated our forecast through Monday afternoon to
significantly increase the risk of accumulating snow near and west
of US-131. There are two periods of significant lift in the DGZ
that also increase the inversion heights, the first one comes
through between midnight and just after sunrise, the second one
toward evening. The GFS, RAP, various versions of the HRRR (many
runs in a row) the RAP model, NAM, NAMNEST all show these
features. So I now have significantly higher QPF near US-31
between South Haven and Grand Haven, as far inland as Sparta in
NE Kent County.

Both the HRRR and NAMNEST show a mesolow developing near Holland
early Monday morning moving on shore over central Ottawa County.
This would locally enhance the snowfall. I could see 2-4" falling
in this area. Given all the snow we have seen in the past few days
I see no reason to issue Winter Weather Advisory at this point
since the wind will not be much of a factor.

The second feature is that system that mostly passes south of this
area in the evening but it still provides lift in the DGZ so
snowfall will be enhanced once again. All totaled I have 2 to 4
inches of snow in this area by Monday evening.

&&

.DISCUSSION...(This evening through next Sunday)
Issued at 223 PM EST Sun Feb 7 2021

- Cold and snowy pattern through next weekend

The next several days will feature a continuation of arctic air
and lake effect snow showers, with periodic chances for synoptic
snow as waves of low pressure move along a persistent baroclinic
zone across the Ohio Valley. The DGZ remains near the surface and
inversion heights generally below 5 kft means lake effect snow
will be light and fluffy and amounts not excessively heavy.

A minor snow event similar to last night is expected Monday night
as a weak low tracks though the Ohio Valley with 1 to 2 inches of
snow most places and some lake enhancement boosting totals into
the 2 to 4 inch range across the southwest forecast area.

We continue to watch the evolution of the low ejecting northeast
out of the Gulf mid to late week. Still a low confidence snowfall
forecast due to the wide ensemble spread. ECMWF continues to be
more bullish than the GFS for the snow potential with the low
progged to track further east.

The core of the cold air with 850 mb temps -25C to -30C still
seems poised to arrive this weekend as shown in the 12Z guidance
from the GFS and ECMWF. This would mean high temperatures in the
single digits and even below zero away from Lake Michigan. The
model blend temperatures are not that cold since there has been
some uncertainty on when or if that cold core makes its way to
Michigan.

Temperature forecasting will be challenging this week as the
arctic air and fresh snow cover means any clearing could result in
temperatures at night falling well below zero. We saw that happen
last night as interior locations where skies cleared out had lows
of 5 to 15 below.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 630 PM EST Sun Feb 7 2021

Light snow showers persist along the lake shore at locations like
BIV, MKG, LWA with MVFR to briefly IFR in the stronger snow
showers but the inland TAF sites like JXN have only scattered
clouds. Through the evening I do not see this changing to much.
The snow showers should have a hard time reaching US-131 through
the evening. Still the US-131 TAF sites (GRR, BTL and AZO) should
continue to have MVFR cigs.

Overnight a shortwave heads this way and will flair up the snow
showers after 06z. Seems a mesolow may develop by morning near BIV
and move onshore south of MKG by late morning. This will bring
widespread IFR in snow to both the US-131 TAF sites and to MKG.
Even LAN and JXN may see some snow showers from the shortwave
around sunrise. A second system moving into the area will increase
the snow showers activity by mid to late afternoon once again.
Overall expect snow with IFR conditions at all but JXN and LAN
most of the day Monday. Even LAN and JXN may occasionally be IFR
through.


&&

.MARINE...
Issued at 223 PM EST Sun Feb 7 2021

No changes to Small Craft Advisory. Webcams show ice rapidly
expanding near shore and this will continue through the week as
the cold weather persists.


&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&

$$

UPDATE...WDM
SYNOPSIS...Ostuno
DISCUSSION...Ostuno
AVIATION...WDM
MARINE...Ostuno



Area Forecast Discussion

National Weather Service Gray ME

 1018 PM EST Sun Feb 7 2021

.SYNOPSIS...
Coastal storm is sliding just southeast of the area this
evening, but just 30 to 50 miles south very heavy snow is
falling across parts of Massachusetts and the Gulf of Maine.
Any remaining light snow will quickly move out this evening and
give way to a fair but cold day Monday. The storm track will
remain active through the coming work week with a couple chances
for snow. The first will be midweek and then another threat at
the end of the week punctuated by periods of quiet of high
pressure.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
10:00 UPDATE....Very little change to the ongoing forecast other
than minor adjustments to PoPs and temperatures to better match
trends and observations. The Winter Weather Advisory for York
and coastal Cumberland county was also cancelled as little to no
additional snow accumulation is expected.

8:00 PM UPDATE... Adjustments to PoPs were made
to better match recent radar scans, which shows the steadiest
snow now moving out of New Hampshire and gradually moving out of
southwestern Maine. As a result, the Winter Weather Advisory
for New Hampshire was cancelled in this update as little to no
additional accumulation is expected. There is another relatively
weak band of snow to our west across Vermont, which is
associated with the cold front that is moving east. This may
allow for a light coating of new snow across portions of New
Hampshire but these amounts are expected to be very minimal. The
Advisory for Maine was left in place for now as up to an
additional 1" of accumulation will be possible in spots. Other
than some minor adjustments to temperatures and winds, the rest
of the forecast remains well on track.

Very classic lateral quasi- stationary band moving across Srn
New England this afternoon will begin to ride NE thru the Gulf
of ME this evening. RAP forecasts had a very good handle on the
location of this band and I leaned on its forecast thru the
evening. Motion of the upper jet streak...mid level trof...and
mid level frontogenesis more or less keep best forcing headed
for Nova Scotia. I do expect plenty of light snow to the N of
the most intense band...so I have very high PoP despite lower
QPF. I will keep advisories in place along the coast and in Srn
NH...but mainly expect 2 to 4 inches in these locations and less
to the N. I could see a local 5 inch report near the Seacoast
or around Penobscot Bay but that should be upper bound.

I have also sped up the end time for the steady snow based on
latest forecast guidance. Any real chance at accumulation will
quickly end from W to E between about 5 pm and 9 pm. Just ahead
of the trof axis there may be a line of snow showers...but these
should be fairly brief and little accumulation is expected.

Blended raw 2 m temps into the trend tonight as CAA should keep
things fairly well mixed in the boundary layer.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
In the wake of low pressure Mon will be much colder. Temps will
struggle out of the mid 20s near the coast and teens in the
North Country. Otherwise it will be a dry but breezy day. A
weak PGF and low dew points will allow temperatures to quickly
drop after sunset Monday night... but will slow or plateau as
clouds increase from the southwest ahead of the next system.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
Same story for the extended today as has been told for a few
days now... a stout, persistent upper level vortex will
continue to swirl over central Canada with shortwaves embedded
within the circulation occasionally tracking through the
northern CONUS. Looking to ensembles through the extended, there
remains a consistent signal pointing to below average
temperatures for the period with daily highs in the teens and
20s, give or take a few degrees as weak waves come and go.

Starting early Tuesday...high pressure extending through Quebec and
New England deflects north as a shortwave trough quickly skirts
across the Ohio Valley to the southern coast of New England.
This quick-hitting system brings a light snowfall to the region,
but could be briefly moderate particularly at the coast if an
onshore component to the circulation produces some ocean
enhancement or stronger FGEN forcing. Will keep an eye on model
trends but probabilities point to a 2-4" snowfall event with
highest totals likely over southern and coastal zones, closest
to the forcing. It bears mentioning that model trends have been
toward lower QPF... so outside the upslopes the north escapes
accumulations above about an inch while accumulations further
south may rely on some fluff factor. There remains some timing
differences within the model suite, but in general light snow
will come into New Hampshire starting Tuesday morning. The
steadier snow likely impacts the Tuesday evening commute, then
the system exits Tuesday night with upslope snow showers
remaining Wednesday.

A northwest breeze on Wednesday is replaced by high pressure nosing
in from Canada through Thursday. By Thursday night, the next
shortwave rotates around the Canadian low and brings another storm
system to the eastern CONUS as it absorbs a southern stream wave.
Details are of course scant at this stage but this system follows
the same cadence as others in this storm pattern... low pressure
forming over the baroclinic zone separating the Arctic air mass to
the north from the warmer air mass to the south, generally over the
Ohio and Tennessee Valleys, quickly tracks east to the coast by
around early Friday. The trend has been placing this storm track
further south, however... so this system may give us nothing more
than a glancing blow. Another wave rotates through toward the end of
the weekend but with little model consensus to grasp onto.

&&

.AVIATION /03Z MONDAY THROUGH FRIDAY/...
Short Term...Widespread LIFR will continue into the evening
hours. Relatively fast clearing to VFR is expected from W to E
as the trof pulls Ewd. VFR conditions in Coos County due to
downsloping will give way to upslope later tonight and MVFR
CIGs are possible and VCSH expected near HIE. VFR conditions
Mon.

Long Term...Ceilings lower to MVFR on Tuesday with -SN
overspreading at least southern terminals during the day with
localized IFR possible in SN. Restrictions lift for all sites by
early Wednesday, except for at KHIE where -SHSN may linger into
mid-day with northwest winds taking hold. VFR prevails
thereafter until the next system approaches late in the week.

&&

.MARINE...
Short Term...SCAs remain in effect for N flow becoming gusty
offshore tonight. Seas will remain above 5 ft into Mon evening.
Much colder temps will bring the threat of freezing spray to the
waters again.

Long Term...A wave of low pressure crosses south of the waters
late Tuesday into early Wednesday which may bring gusty
offshore winds in its wake to SCA thresholds. High pressure
builds into the waters thereafter with another wave approaching
late in the week.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Winter Weather Advisory until midnight EST tonight for MEZ022-
     025>028.
NH...None.
MARINE...Small Craft Advisory until 2 PM EST Monday for ANZ151-153.
     Small Craft Advisory until 7 PM EST Monday for ANZ150-152-154.

&&

$$
NEAR TERM...Tubbs




Area Forecast Discussion

National Weather Service North Platte NE

 626 PM CST Sun Feb 7 2021

.SHORT TERM...(This evening through Monday night)
Issued at 403 PM CST Sun Feb 7 2021

The main forecast challenges heading into early next week continue
to revolve around snow and temperatures. Two areas of snow (one
ongoing and one forecast) will affect the area through tonight,
while temps remain subfreezing essentially all week.

A current batch of snow showers, some on the heavier side, is
working through the Sandhills. Extended the WW.Y for E.Cherry to
Custer and points east to account for this activity. Moisture
amounts have been generally around 0.10" so far with that per VTN.
This is on the higher side of guidance and is likely translating to
almost 2" of snow given SLR`s around 17:1. Drier air is filling in
behind it with most of the saturation being kept near the surface
toward GRN. Expect this activity to move out of the forecast area by
00z. A mid-level front remains situated across southern Nebraska and
will be the focus for more development tonight. Snow should become
more organized after 00z and strengthen through the evening.
NAMnest, which has been faring relatively well the past couple
evenings, and the higher res GFS to a degree, suggest a narrow fgen
band along I-80. Again, HRRR is less aggressive and hints at some
banding overnight. Soundings indicate a classic snow sounding at LBF
in terms of thermal/moisture profile, but lift does not appear as
strong as last night`s system. Cross sections also indicate
primarily neutral EPV and perhaps brief instability. Isentropic
upglide continues to be prevalent south of the interstate, while
downglide takes over to the north. As such, increased PoP to high
end chc along I-80 this evening and taper to the north. QPF is a
little more tricky due to supposed weaker forcing and how narrow the
band would be. Went with a broadbrushed 0.05" or so, but definitely
cannot rule out more in the center of the band. When combined with
16-17:1 SLR`s, this should translate to around 1" of snow and
locally higher. For now, held off a new WW.Y for southwest Neb.
Heading toward Monday morning, the dynamics for the forecast snow
band fall apart, but isentropic upglide resumes across the Sandhills
as the front pushes north. Introduced new schc-chc PoP through early
afternoon along/north of Hwy 2. For now, moisture appears to be
somewhat limited and forcing favors more scattered activity
resulting in 1/2" in spots. Temperature-wise, nudged tonight`s lows
and tomorrow`s highs down a couple degrees. Hedged on the cooler end
of guidance as today`s temps were stagnant in the single digits.
Much of the region should drop below zero tonight as H85 temps
approach -20C north and -15C south and added depth to the snowpack.
Kept western Neb in the teens tomorrow as the ensembles actually
bring in a weak WAA scheme. North central Neb should remain in the
single digits again, partly due to additional snow and clouds later
into the day.

.LONG TERM...(Tuesday through Sunday)
Issued at 403 PM CST Sun Feb 7 2021

For the rest of the workweek, bitter cold remains the top weather
story as the large upper trough sits on top of the northern US.
While discrepancies exist in the magnitude of the cold and the track
of the main lobe of Arctic air, western Nebraska should remain
subfreezing nonetheless. Friday and Saturday mornings are gearing up
to be the coldest of the week with widespread lows around -10F. Of
course, more disturbances roll through along the trough. Confidence
is increasing for more organized snowfall later in the week, mainly
Wednesday night through Friday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 624 PM CST Sun Feb 7 2021

Widespread MVFR conditions are forecast to persist tonight and
into Monday across western and north central Nebraska. Some
isolated IFR is possible. Areas of light snow can be expected,
mainly tonight. Winds will be generally east to southeast at 5-10
kts.

&&

.LBF WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 9 PM CST this evening for NEZ010-
028-029.

&&

$$

SHORT TERM...Snively
LONG TERM...Snively
AVIATION...Taylor



Area Forecast Discussion

National Weather Service Memphis TN

 832 PM CST Sun Feb 7 2021

.DISCUSSION...
Clear skies over a portion of northwest Tennessee near the
Tennessee River is filling in with some low clouds as expected.
The temperatures in the Mid-South should drop only a little due
to the cloud cover. So current forecast is on track. No update
planned at this time.  TLSJr

&&

.PREV DISCUSSION... /issued 342 PM CST Sun Feb 7 2021/

DISCUSSION...

A cold day ongoing across the Mid-South at this hour. Much of
northeast Arkansas failed to get out of the upper 20s this
afternoon and wind chills have remained in the teens. This was in
large part to moderate CAA and heavy cloud cover today. Further
south, temperatures only reached the mid to upper 30s. Latest
surface analysis places a cold front from Ottawa, Canada back
through Appalachia and into north Mississippi.

The front is expected to remain nearly stationary over north
Mississippi overnight as upper level flow remains zonal. Heavy
cloud cover will also keep temperatures from falling much overnight.
By tomorrow afternoon, a surface low will slowly eject out of the
Southern Plains and upper level flow will shift more
southwesterly. This will help lift the front back as a warm front
during the day on Monday. The front will likely stall somewhere
north of I-40. Temperatures south of the front will warm back into
the upper 50s to lower 60s, with upper 40s to lower 50s along the
front. Expect a dry and pleasant day.

Some light overrunning precipitation could begin as early Tuesday
morning, in response to a weak shortwave translating through
southwest flow aloft. Any places that see precipitation should see
a cold scattered rain throughout the afternoon hours. There is a
low chance of freezing rain across extreme northeast Arkansas
during Tuesday night, as temperatures remain near freezing.

The forecast Wednesday night through Friday morning still
contains a lot of uncertainty, which is mainly a dispute about
where the arctic front sets up through this period. The EURO
continues to remain bullish with all the subfreezing air remaining
just north of the forecast area, meaning almost no wintry weather
for our forecast area. However, the GFS and GDPS continue to
bring the arctic air further south to the I-40 corridor. This
solution translates to at least some light icing north of I-40,
with the potential for a tenth of an inch or more. BUFR soundings
still show a shallow subfreezing airmass, with temperature traces
mainly indicative of freezing rain event. Snow looks like a very
low possibility at this point, due to the rather large warm nose
between 850 and 925mb.

Beyond Friday is literally a crap-shoot. Both high and low
temperatures are currently a difference of 20 degrees or more
from the EURO to the GFS. It will be very cold or basically near
normal, depending upon a piece of the Polar Vortex invading the
Mississippi Valley this upcoming weekend. We will try to nail
down the forecast for Wednesday and Thursday and then take it from
there. For now, went with a blend with lows in the teens and
highs around freezing each day through the weekend.

AC3

&&

.AVIATION...
00Z TAFs

Moisture will remain locked in below FL030 through the overnight.
Expect the clear area near and to the north of MKL, east of JBR to
fill in through the evening, as the layer below cools. There is a
limited chance of IFR over these areas, if the overlying MVFR deck
is slow to redevelop. The HRRR appears to concur.

VFR should develop behind a northward-surging warm front Monday
morning, reaching JBR later Monday afternoon. MEM looking at warm
sector IFR and perhaps drizzle developing after TAF expiration of
06Z/09, near the end of the arrival push.

PWB

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...None.
MO...None.
MS...None.
TN...None.
&&

$$