Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/25/21

AREA FORECAST DISCUSSION

National Weather Service Albany NY

 943 PM EST Fri Dec 24 2021

.SYNOPSIS...
Dry but cloudy weather is expected for the remainder of
Christmas Eve afternoon and through the evening. Tonight, another
system will approach from the west, bringing with it mixed
precipitation including freezing rain. Freezing rain gradually
transitions to rain Christmas Day before ending during the evening.
A trend to drier weather is expected Sunday, though some lake-effect
and upslope rain and snow showers may linger.

&&

.NEAR TERM /UNTIL 7 AM SATURDAY/...

.A Winter Weather Advisory has been issued for Windham County
in southern Vermont 1 am tonight to 7 pm Saturday...

.A Winter Weather Advisory has been issued for the Mohawk Valley,
Adirondacks, Lake George Saratoga Region, Bennington County in southern
Vermont and western Massachusetts from 10 pm tonight to 1 pm
Saturday...

.A Winter Weather Advisory has been issued for the Schoharie Valley,
eastern Catskills, Capital District, Taconics, mid-Hudson Valley and
northwestern Connecticut from 10 pm tonight to 10 am Saturday...


Updated at 945 pm. Warm air continues to push eastward from
western NY while cold air holds on over the eastern half of NY.
Temperatures currently are ranging from the mid 50s in southwest
NY to the teens in the northeast. Still expecting precipitation
to develop near I-81 in central NY toward midnight, then move
east across our area during the predawn hours. Temperatures will
be slowly rising through the 20s and this precipitation will
begin as freezing rain in many areas. Temperatures will be
rising to near or possibly even slightly above freezing east of
the Hudson River due to light southeasterly downslope from the
Taconics in that area, so that area may escape any icing.
However west of the Hudson River a glaze can be expected by
daybreak.

Updated at 715 pm. Low pressure moving east across the southern
Great Lakes is pushing an unseasonably warm air mass over the
midwest eastard toward eastern NY and western New England.
However as is often the case this airmass will meet stubbourn
resistance as it tries to dislodge the cold air established
across our area. Temperatures at 7 pm across NY state on the
mesonet range from lower 50s across the southwest to single
digits in the far northeast. Most of our area is in the 20s.
Precipiation will develop across our area later tonight as the
warm air from the west is forced up and over the cold air in
eastern NY. Precipitation through 12z will be mainly in the form
of freezing rain with a little sleet possible at the onset.
Latest operational models are consistent with previous runs
indicating that precipitation will blossum over eastern NY, then
the steadiest precipitation will move across the region on
Saturday morning, Temperatures will rise slowly overnight
through Saturday morning, allowing for a change to light rain in
most areas by late morning, with the exception of a few cold
pockets mainly north of the Capital District. Previous
discussion is below.

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...

One forecast challenge tomorrow is whether or not there will be
a lull in the precip during the mid-morning hours Christmas
morning. The NAM has two separate waves of precip, while the
HRRR brings in the second wave sooner. Other guidance is
generally somewhere in between these two solutions. The societal
impacts will be similar regardless of whether or not there is a
lull mid-morning, however. Freezing rain accumulation generally
looks to range from a glaze to 0.1" for most areas south of the
Capital District (with the exception of higher elevations where
around 0.1-0.2" is possible), 0.1-0.25" for the Mohawk Valley
and upper Hudson Valley into southern VT, as well as the
southern Adirondacks. There may be a few spots in Windham County
(and the southern Adirondacks as well) that receive between a
quarter and a third of an inch of freezing rain. While this is
sub ice-storm warning criteria, travel may nevertheless become
difficult late tonight and tomorrow for areas experiencing
freezing rain, so use caution and give yourself extra time to
reach your destination tomorrow.

Saturday night, the upper disturbance and associated surface low
move off to the east, causing precip to wind down across the
region. We switch to cold air advection behind as the system
pulls away, so some mixed rain/snow/sleet showers will be
possible tomorrow evening and early tomorrow night, but
additional accumulation (if any) looks relatively minor. Will
also note that many areas will fall back below freezing by 12z
Sunday, so any standing water on roads and walkways may re-
freeze, possibly resulting in continued slippery travel
conditions Saturday night as well.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Quite a bit of uncertainty in terms of the precipitation pattern
especially as it relates to the finer details during the long-term
period. Given the situation, at this point, the pattern looks mostly
dry, yet progressive during this period. The best chance for
precipitation looks to be during the middle portions of this period.
Temperatures are expected to run normal than normal level during
this time frame.

We start off the long-term forecast period on Sunday with mainly dry
conditions as storm system departs to our east. On the backside of
this departing storm system and in a cold air regime, there could be
some lingering lake effect and orographically enhanced snow showers.
These snow showers should wane as the day progresses on Sunday.

Sunday night into Monday, the deterministic forecast models and their
ensembles are depicting a storm system developing over the north-
central U.S. As this storm system translates eastward, forecast
models/ensembles are indicating the system fizzling out. Given that
computer models signal this storm system losing steam, have kept the
forecast dry on Monday over the area.

On the heels of the first storm system that fizzles out, will be a
second storm system that computer models are projecting to develop
over the central U.S. Monday night into Tuesday. Tapping into to
Gulf of Mexico waters and associated with the southern stream, this
storm system has the potential to bring us our next widespread
precipitation Tuesday evening into Wednesday.

The GFS/GEM models has the area drying out during the second half of
Wednesday with a southern stream wave well off to our south.
However, the ECMWF keeps the area wet through Wednesday into
Thursday as it tracks the southern wave further north and faster
into our area. Given the differences amongst guidances, have only
included chance PoPs second half of Wednesday into Thursday.

Thursday PM into Saturday or through the rest of the extended looks
mainly dry and tranquil.

Temperature anomalies will run warmer than normal levels during this
period with daytime highs mostly in the upper 30s to lower 40s along
the river valleys and overnight lows in the mid to upper 20s to mid
30s across the lower elevation areas. &&

.AVIATION /21Z FRIDAY THROUGH WEDNESDAY/...
Through 00z Sunday...As of 6:15 PM EST, MVFR cigs were sited at the
terminals with cloud bases ranging between 1,000-2,000ft. These low
to mid clouds are preceding the arrival of freezing rain which is
expected to overspread the area shortly after midnight. Once the
freezing rain arrives, expect for MVFR-LIFR cigs and/or vis to
develop. Shortly after daybreak, with the exception of KGFL,
freezing rain is expected to transition over to rain as temperatures
increase. KGFL should see the transition take place in the
afternoon. Rain should continue into the late afternoon/early
evening hours over the TAF sites with the exception of KGFL, which
is expected to see rain persist through the TAF period. MVFR-LIFR
conditions will persist through the remainder of the TAF period
thanks to clouds which could fall as low as under 1,000ft.

Winds are expected to remain calm, if not, light and variable
through the TAF cycle.

Outlook...

Saturday Night: Moderate Operational Impact. Chance of SHRA...SHSN.
Sunday: Low Operational Impact. Slight Chance of SHRA...SHSN.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: Low Operational Impact. Slight Chance of SHSN.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: Low Operational Impact. Slight Chance of SHRA.
Tuesday Night: Moderate Operational Impact. Chance of SHRA...SHSN.
Wednesday: Moderate Operational Impact. Chance of SHRA...SHSN.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Through 00z Sunday...As of 6:15 PM EST, MVFR cigs were sited at the
terminals with cloud bases ranging between 1,000-2,000ft. These low
to mid clouds are preceding the arrival of freezing rain which is
expected to overspread the area shortly after midnight. Once the
freezing rain arrives, expect for MVFR-LIFR cigs and/or vis to
develop. Shortly after daybreak, with the exception of KGFL,
freezing rain is expected to transition over to rain as temperatures
increase. KGFL should see the transition take place in the
afternoon. Rain should continue into the late afternoon/early
evening hours over the TAF sites with the exception of KGFL, which
is expected to see rain persist through the TAF period. MVFR-LIFR
conditions will persist through the remainder of the TAF period
thanks to clouds which could fall as low as under 1,000ft.

Winds are expected to remain calm, if not, light and variable
through the TAF cycle.

&&

.HYDROLOGY...
No widespread or significant issues are expected on the main
stem rivers into early next week. Flows will likely hold steady
or through Saturday morning, with some within-bank rises
possible Saturday afternoon through Sunday morning.

For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Winter Weather Advisory until 10 AM EST Saturday for CTZ001-
     013.
NY...Winter Weather Advisory until 10 AM EST Saturday for NYZ047-
     051>054-058>061-063>066.
     Winter Weather Advisory until 1 PM EST Saturday for NYZ032-033-
     038>043-048>050-082>084.
MA...Winter Weather Advisory until 1 PM EST Saturday for MAZ001-025.
VT...Winter Weather Advisory until 1 PM EST Saturday for VTZ013.
     Winter Weather Advisory from 1 AM to 7 PM EST Saturday for
     VTZ014-015.

&&

$$
SYNOPSIS...Main/Rathbun
NEAR TERM...MSE/Main
SHORT TERM...Evbuoma
LONG TERM...Evbuoma
AVIATION...Evbuoma
HYDROLOGY...Main/Rathbun



Area Forecast Discussion

National Weather Service Marquette MI

 536 PM EST Fri Dec 24 2021

.SHORT TERM...(This evening through Saturday)
Issued at 453 PM EST FRI DEC 24 2021

Water vapor imagery and RAP analysis show a shortwave trof extending
from central Saskatchewan se toward Lake Superior. Associated broad
sfc low is centered just e of Lake Winnipeg with cold front arcing s
across MN. Ahead of the front, abundant low-level moisture is
resulting in low clouds and fog across most of the fcst area. Where
sse flow is upsloping into central Upper MI, the fog has become
locally dense. Left exit of 150kt upper jet extending from SD across
southern MN into central WI is supporting an area of -ra that is
spreading ne into central Upper MI. It`s a mild Christmas Eve day
with temps currently in the mid to upper 30s F across the board.

Expect aforementioned area of -ra to spread quickly ene over the
next few hrs. The -ra should tend to linger over the e or may
transition to more of a -dz during the evening as the approaching
cold front will not clear the fcst area until around 06z. There
could be a little postfrontal wnw upslope flow -dz/-fzdz over the nw
fcst area. There`s not a lot of low cloudiness in northern MN, so
potential looks limited at this point. Until the front passes,
upslope sse flow will support fog, especially across the central
fcst area where this flow is more strongly upsloping. However,
locally dense fog will likely spread eastward thru the evening hrs
as dwpts rise farther e, especially once the -ra diminishes. The fog
and low clouds will thin out after fropa tonight. Expect min temps
ranging from around 15F far w to 30 far e.

Christmas Day will be a dry day for much of the fcst area, and there
may be a fair amount of sunshine for a time thru the morning,
especially where nw winds downslope. Next shortwave will be moving
out across the Northern Plains and will be approaching Upper MI by
evening. Deep layer forcing ahead of the wave should support some
-sn streaking e into western Upper MI late in the aftn with high and
mid clouds spreading across the rest of the area. Upper diffluence
resulting from a 140kt upper jet streak running from Nebraska/SD
toward southern Lake MI and a secondary much weaker jet streak vcnty
of the U.S./Canada border will further support -sn development. Snow
accumulations should be under 1 inch by 00z Sun. Expect high temps
to range from generally the mid 20s F w to the lwr 30s s central and
e.

.LONG TERM...(Saturday night through Friday)
Issued at 535 PM EST FRI DEC 24 2021

A very active extended period is expected across Upper Michigan with
several perturbations ahead of a deep trough progged to hit the west
coast on Sunday.  First, a shortwave will continue its progression
through the forecast area on Saturday night.  Strong forcing fueled
by a 150kt upper level jet will intensify snow development,
especially in the Sun 00-06Z time frame.  A quick 1 to 3 inches will
be possible over the western portions of the forecast area.  Per
CAMs, any LES potential in the wake of the clipper will be minimal.

After a brief lull on Sunday, focus quickly turns to the next wave
pivoting around the aforementioned west coast trough.  Isentropic
lift will ramp up with this disturbance in the Mon 06Z-Tue 00Z time
frame.  Significant snow accumulations will be possible with the
Keweenaw likely being hit the hardest.

Further out, the west coast system will finally move into Manitoba
on Tuesday giving Upper Michigan yet another round of accumulating
snow.  Meanwhile, temperatures through the period will generally be
above normal until a colder airmass overspreads the region late
in the period.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1248 PM EST FRI DEC 24 2021

Abundant low-level moisture will be in place until a cold front
passes this evening. Ahead of the front this aftn, LLWS will also
continue as low-level jet translates across the area. At the sfc,
winds should gust upwards of 25kt this aftn, especially at IWD/SAW.

At IWD, expect MVFR conditions to prevail this aftn, though cigs may
slip to IFR at times. Cigs may scatter out to VFR with fropa early
this evening, but MVFR cigs should return for several hrs late
evening/overnight. Expect VFR again by morning.

At CMX, VFR conditions should give way to MVFR cigs in the next few
hrs. MVFR cigs should then prevail for the remainder of the fcst
period.

At SAW, LIFR conditions will prevail until fropa late this evening.
Not out of the question that conditions could fall blo airfield
landing mins. Some -ra is expected for a few hrs this aftn. Expect
improvement overnight to MVFR with further improvement to VFR by
daybreak.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 453 PM EST FRI DEC 24 2021

SSE gales of 35-40 knots across the e half of Lake Superior will
diminish to below gale force early this evening as low-level jet
ahead of approaching cold front shifts e of the lake. Cold front
will cross the lake thru the evening hrs, resulting in a wind shift
to the nw at 25-30kt. Across the e half, there may be some gale
force gusts to 35kt late tonight and Sat morning. Winds will then
diminish thru Sat night, falling to under 20kt across the entire
lake for Sun. Next low pres will then lift ne toward the Upper Great
Lakes Sun night. E to SE winds will ramp up ahead of it, likely
reaching 35-40kt gales across much of central and eastern Lake
Superior late Sun night and Mon morning. After the system passes,
expect westerly winds of 20-30kt across much of Lake Superior into
Mon evening. Winds will then briefly subside to blo 20kt for Tue
morning before increasing ahead of the next low pres which will take
a similar track to the previous low. May end up with another e to se
gale Tue night and potentially a westerly gale after it passes on
Wed.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Dense Fog Advisory until 1 AM EST /midnight CST/ Saturday for
     MIZ004>006-010>013.

  Dense Fog Advisory until 3 AM EST Saturday for MIZ007-014-085.

Lake Superior...
  Gale Warning until 7 PM EST this evening for LSZ266-267.

Lake Michigan...
None.
&&

$$

SHORT TERM...Rolfson
LONG TERM...TDUD
AVIATION...Rolfson
MARINE...Rolfson