Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
313 AM EST Tue Jan 25 2022

Valid 12Z Tue Jan 25 2022 - 12Z Thu Jan 27 2022

...Light to moderate snow will move through New England today before a
clipper system exit the region tonight...

...Showers across the Gulf Coast states will spread into Florida later
today...

...Arctic air will plunge into the eastern two-thirds of the country with
a round of snow today across the central/southern Rockies and High
Plains...

An Alberta clipper moving into New England early today will bring with it
a quick round of scattered light to moderate snow through the interior
sections of the Northeast and down toward the central Appalachians before
exiting the region tonight. An arctic air mass in the wake of the clipper
will continue to plunge into the Plains today and then through much of the
eastern U.S. by Wednesday. Sub-zero temperatures will be common across
the northern Plains to the upper Midwest through Wednesday morning with
wind chills potentially reaching -40 degrees. This cold snap will be
somewhat short-lived across the northern U.S. as a quick rebound to above
normal temperatures is expected to spread eastward from the northern High
Plains later on Wednesday into Thursday with the passage of a warm front.
However, much of the eastern half of the country down into the South will
be under the grip of this arctic air mass into Thursday morning. Areas of
lake-effect snow can be expected to linger near the downwind side of the
Great Lakes into Thursday morning.

Meanwhile, a low pressure system tracking eastward across the northern
tier of the Gulf of Mexico will continue to bring a round of showers and
possibly a few thunderstorms from west to east through the Gulf Coast
states early today before reaching the Florida Peninsula this afternoon
into tonight. This system is forecast to weaken but will become
slow-moving as it reaches Florida on Wednesday, thereby keeping a good
chance of showers and possibly thunderstorms across the southern half of
Florida into Thursday morning.

Farther to the north, a shortwave impulse diving down the spine of the
Rockies will trigger a round of snow showers today and tonight from the
central to southern Rockies as well as the nearby High Plains. The area
of snow should reach the southern High Plains on Wednesday and then toward
Oklahoma Wednesday night as the shortwave impulse continues to dive
farther southward.

Kong


Graphics are available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
152 AM EST Tue Jan 25 2022

Valid 12Z Fri Jan 28 2022 - 12Z Tue Feb 01 2022

...Winter Coastal Storm Threat from the Mid-Atlantic to especially
New England Friday into the Weekend...


...Overview...

From late this week to the start of next week the models and
ensembles continue to show an upper level pattern consisting of a
mean trough over the East, varying degrees of ridging over the
West, and a developing northeastern Pacific trough that should
approach/reach the West Coast. Guidance expects the inland
progression of the Pacific trough by Monday-Tuesday to flip the
pattern somewhat, with decreasing heights over the West and rising
heights over the East. Perhaps due in part from improving
agreement for a lead Pacific shortwave/possible weak embedded low
nearing California by Saturday, there is likewise narrowing spread
of solutions for energy digging into an amplified U.S. trough that
looks increasingly likely to support a significant and rapidly
deepening western Atlantic coastal storm Friday into the weekend
with effects from the Mid-Atlantic to New England in particular.
Some differences persist for details of the upper trough moving
into the West.

...Guidance Evaluation/Predictability Assessment...

Emerging trends from yesterday along both coasts of the lower 48
during the late week/weekend time frame held up fairly well in the
12Z/18Z cycle of guidance. Slower and more separated evolution of
the shortwave approaching California, likely yielding a weak upper
low, allows for a more persistent upper ridge over the West and in
turn somewhat stronger and slightly westward digging of shortwave
energy (which is finally reaching northwestern North America
today) into the East. Yet to be resolved is exactly when and where
eastern energy closes off an upper low, with 12Z/18Z GFS runs
doing so a bit later/northeastward than other models. In the new
00Z cycle the CMC has deviated significantly from other guidance
over the eastern Pacific, leading to question marks in its
forecast farther eastward--specifically a storm track a bit to the
east of consensus versus multiple prior runs that were on the
western side. Some important fine-scale details will still take a
while to be resolved satisfactorily. A multi-model blend with some
manual enhancement to maintain continuity in depth also provided
reasonable consistency for a track just offshore New England.

The relatively small and weak nature of the upper low that may
track into the Southwest this weekend could still lead to
predictability issues for a while. Trends over the past day have
been slower, delaying the development of any potential
precipitation along and north of the Gulf Coast. The new 00Z ECMWF
has trended faster though. There is still a wide array of possible
tracks after emerging from the Southwest early next week, with GFS
runs tending to be the farthest north and thus driest.

The upper trough eventually reaching into the western U.S. will be
from some combination of progressive North Pacific energy and flow
descending from Alaska. Differences by day 7 Tuesday are within
the realm of typical guidance spread/error at that time frame but
depend in part on whether there is a break in Pacific and
Alaska/Siberia upper ridging (GFS/GEFS keep it connected, most
other guidance shows a break), an issue that can ultimately lead
to more significant differences over the lower 48.

The aforementioned model blend used for the western Atlantic storm
worked well elsewhere for the first half of the period as well.
The forecast then transitioned toward half models/half means by
late in the period to resolve some of the timing and detail
differences that arise.

...Weather Highlights/Threats...

Key Messages for January 28-30 (Friday-Weekend) Winter Storm:
Confidence is increasing that a significant winter storm will
create considerable impacts Friday through the weekend from the
Mid-Atlantic through the Northeast. While uncertainty continues
with the track and intensity of this system, it is becoming more
likely that it will bring significant snow, sleet, and freezing
rain to the region, including the I-95 metropolitan areas.
Hazardous travel conditions are possible due to the combination of
snow, sleet, freezing rain, and wind. Close to the immediate
Atlantic coastline, strong winds combined with high astronomical
tides may lead to coastal flooding. Please continue to monitor for
future updates as this system develops.

Currently it appears that the upper trough/low that may track into
California and the Southwest this weekend could be weak enough not
to produce much if any precipitation over that region. Its
strength and track thereafter will determine how much
precipitation may develop from the Gulf Coast northward by the
first part of next week. Confidence is very low given a wide array
of possibilities between meaningful amounts and dry conditions.
Ahead of the northeastern Pacific upper trough, moisture should
begin to move into the Northwest on Sunday and then continue to
spread across more of the West with time. Highest totals of
rain/mountain snow should be over the Pacific Northwest. A series
of waves/fronts may bring episodes of light and scattered snow
into parts of the Great Lakes.

Much of the eastern half of the country will be quite chilly
through the weekend, with Saturday-Sunday having the broadest
coverage of temperatures 10-20F below normal. Expect a warming
trend to bring readings back close to normal by Monday or Tuesday.
Much of the Plains will see above normal temperatures (up to plus
10-20F anomalies) late this week into Monday, aside from a cool
Friday over far southern areas. Northern locations will see a
colder trend Monday-Tuesday while the relative warmth farther
south spreads a bit farther eastward. The West should see plus
5-10F or so anomalies through the weekend followed by a cooler
trend early next week as upper troughing moves in.

Rausch/Schichtel


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation, winter weather outlook probabilities
and heat indices are at:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml

Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
259 AM EST Tue Jan 25 2022

Valid 00Z Wed Jan 26 2022 - 00Z Wed Feb 02 2022

The forecast from now into the first part of the weekend is fairly
consistent and agreeable among the guidance, with a succession of
a couple fronts and trailing highs to the north of the state and
generally near to below average precipitable water values. Trades
may vary somewhat from day to day while the relatively low
moisture should limit rainfall totals over the typical
windward-favored areas or locally elsewhere if winds weaken enough
to allow for some sea/land breeze influence.

By Sunday through Tuesday, the pronounced divergence in guidance
seen yesterday persists. GFS/GEFS runs continue to show more
southeastward upper trough amplitude versus other models and
means. In fact for some 500mb height contours, hardly any 00Z
CMCens/12Z ECens members are as amplified as the 00Z GFS or GEFS
mean. The deeper and sharper GFS/GEFS upper trough leads to
bringing a significant increase of moisture into the main islands
from the west and south as a front moves in, versus the shallower
upper trough in the majority ECMWF cluster that keeps the front
far enough northwest for the main islands to stay in a
lower-moisture trade regime into Tuesday. In addition to a
greater proportion of guidance showing the ECMWF cluster,
multi-day trends in the GFS have been toward gradually less upper
trough depth/amplitude and slower arrival of moisture/rainfall.
This combination seems to favor maintaining a forecast that leans
more in the direction of the ECMWF cluster.

Rausch

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
301 AM EST Tue Jan 25 2022

Day 1
Valid 12Z Tue Jan 25 2022 - 12Z Wed Jan 26 2022

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

A low pressure system will track from the central Gulf of Mexico
toward Florida and will usher rain into western Florida. The
majority of the precipitation will be offshore during this period
but rain rates will be increasing early Wednesday. Areal averages
amongst the latest guidance are up to 1.5 inches. A couple of the
hi-res solutions are showing very isolated rain rates up to 1.5
inches/hours streaking across central Florida. This part of the
state has been very dry lately, with most of the region running 0
to 10% of normal. The soils should be able to handle a few hours
with this rates without having an increased flood threat.

Campbell


Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
303 AM EST Tue Jan 25 2022

Day 2
Valid 12Z Wed Jan 26 2022 - 12Z Thu Jan 27 2022

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Campbell


Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
304 AM EST Tue Jan 25 2022

Day 3
Valid 12Z Thu Jan 27 2022 - 12Z Fri Jan 28 2022

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Campbell

Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
314 AM EST Tue Jan 25 2022

Valid 12Z Tue Jan 25 2022 - 12Z Fri Jan 28 2022

...Great Lakes/Northeast...
Days 1-3...

Broad cyclonic flow centered over Hudson Bay will favor punctuated
bouts of shortwaves rotating through the Upper Midwest/Great
Lakes/Northeast the next few days, with mainly light snow over a
broad area but some focused areas of lake effect snow. Clipper
will exit the Northeast early Day 1 with lake effect ending by
early Day 2 as high pressure moves through the Midwest and winds
become unfavorable. Favored areas on WNW winds will see several
inches into early Wed. At that time, a cold front through southern
Canada will promote warm advection across the western Lakes that
sinks southeastward into Day 3. Amounts will be fairly light under
a few inches. Three-day WPC probabilities of at least 4 inches of
snow focused exclusively on lake effect snow areas.


...Central Rockies and High Plains...
Days 1-3...

Cold front that has already pushed into the Front Range will stall
over the region today and promote an area of modest snowfall in
eastern Colorado on easterly/upslope flow. Mid-level shortwave on
the west side of the Rockies will continue to sink southward into
AZ later today as heights in the mid-level stabilize and the
moisture moves steadily southward into New Mexico. To the east,
models continue to show a region of enhanced mid-level
frontogenesis behind the front over parts of western KS where
snowfall rates of 1"/hr are possible at times per the WPC Snowband
Tool. Placement of this heavier axis remained somewhat elusive per
recent CAM guidance wavering, but a consensus/HREF approach seemed
reasonable. WPC probabilities for more than 4 inches of snow are
high in western KS and northeastern NM where more than 6 inches is
possible. There, synoptic lift combined with moderate upslope
enhancement and periods of robust frontogenesis will drive locally
heavy snow across the Sangre De Cristos.

On Day 2, light snow and snow/rain mix will spread eastward
into/across the TX Panhandle as the shortwave exits NM. Well to
the north, next shortwave in the fast flow will drop into Montana
with another round of light snow moving quickly southward through
Colorado into Day 3. Amounts will be light -- generally 1-3
inches.


For days 1-3, the probability of significant icing is less than 10
percent.


Fracasso

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
152 AM EST Tue Jan 25 2022

Valid 12Z Fri Jan 28 2022 - 12Z Tue Feb 01 2022

...Winter Coastal Storm Threat from the Mid-Atlantic to especially
New England Friday into the Weekend...


...Overview...

From late this week to the start of next week the models and
ensembles continue to show an upper level pattern consisting of a
mean trough over the East, varying degrees of ridging over the
West, and a developing northeastern Pacific trough that should
approach/reach the West Coast. Guidance expects the inland
progression of the Pacific trough by Monday-Tuesday to flip the
pattern somewhat, with decreasing heights over the West and rising
heights over the East. Perhaps due in part from improving
agreement for a lead Pacific shortwave/possible weak embedded low
nearing California by Saturday, there is likewise narrowing spread
of solutions for energy digging into an amplified U.S. trough that
looks increasingly likely to support a significant and rapidly
deepening western Atlantic coastal storm Friday into the weekend
with effects from the Mid-Atlantic to New England in particular.
Some differences persist for details of the upper trough moving
into the West.

...Guidance Evaluation/Predictability Assessment...

Emerging trends from yesterday along both coasts of the lower 48
during the late week/weekend time frame held up fairly well in the
12Z/18Z cycle of guidance. Slower and more separated evolution of
the shortwave approaching California, likely yielding a weak upper
low, allows for a more persistent upper ridge over the West and in
turn somewhat stronger and slightly westward digging of shortwave
energy (which is finally reaching northwestern North America
today) into the East. Yet to be resolved is exactly when and where
eastern energy closes off an upper low, with 12Z/18Z GFS runs
doing so a bit later/northeastward than other models. In the new
00Z cycle the CMC has deviated significantly from other guidance
over the eastern Pacific, leading to question marks in its
forecast farther eastward--specifically a storm track a bit to the
east of consensus versus multiple prior runs that were on the
western side. Some important fine-scale details will still take a
while to be resolved satisfactorily. A multi-model blend with some
manual enhancement to maintain continuity in depth also provided
reasonable consistency for a track just offshore New England.

The relatively small and weak nature of the upper low that may
track into the Southwest this weekend could still lead to
predictability issues for a while. Trends over the past day have
been slower, delaying the development of any potential
precipitation along and north of the Gulf Coast. The new 00Z ECMWF
has trended faster though. There is still a wide array of possible
tracks after emerging from the Southwest early next week, with GFS
runs tending to be the farthest north and thus driest.

The upper trough eventually reaching into the western U.S. will be
from some combination of progressive North Pacific energy and flow
descending from Alaska. Differences by day 7 Tuesday are within
the realm of typical guidance spread/error at that time frame but
depend in part on whether there is a break in Pacific and
Alaska/Siberia upper ridging (GFS/GEFS keep it connected, most
other guidance shows a break), an issue that can ultimately lead
to more significant differences over the lower 48.

The aforementioned model blend used for the western Atlantic storm
worked well elsewhere for the first half of the period as well.
The forecast then transitioned toward half models/half means by
late in the period to resolve some of the timing and detail
differences that arise.

...Weather Highlights/Threats...

Key Messages for January 28-30 (Friday-Weekend) Winter Storm:
Confidence is increasing that a significant winter storm will
create considerable impacts Friday through the weekend from the
Mid-Atlantic through the Northeast. While uncertainty continues
with the track and intensity of this system, it is becoming more
likely that it will bring significant snow, sleet, and freezing
rain to the region, including the I-95 metropolitan areas.
Hazardous travel conditions are possible due to the combination of
snow, sleet, freezing rain, and wind. Close to the immediate
Atlantic coastline, strong winds combined with high astronomical
tides may lead to coastal flooding. Please continue to monitor for
future updates as this system develops.

Currently it appears that the upper trough/low that may track into
California and the Southwest this weekend could be weak enough not
to produce much if any precipitation over that region. Its
strength and track thereafter will determine how much
precipitation may develop from the Gulf Coast northward by the
first part of next week. Confidence is very low given a wide array
of possibilities between meaningful amounts and dry conditions.
Ahead of the northeastern Pacific upper trough, moisture should
begin to move into the Northwest on Sunday and then continue to
spread across more of the West with time. Highest totals of
rain/mountain snow should be over the Pacific Northwest. A series
of waves/fronts may bring episodes of light and scattered snow
into parts of the Great Lakes.

Much of the eastern half of the country will be quite chilly
through the weekend, with Saturday-Sunday having the broadest
coverage of temperatures 10-20F below normal. Expect a warming
trend to bring readings back close to normal by Monday or Tuesday.
Much of the Plains will see above normal temperatures (up to plus
10-20F anomalies) late this week into Monday, aside from a cool
Friday over far southern areas. Northern locations will see a
colder trend Monday-Tuesday while the relative warmth farther
south spreads a bit farther eastward. The West should see plus
5-10F or so anomalies through the weekend followed by a cooler
trend early next week as upper troughing moves in.

Rausch/Schichtel


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation, winter weather outlook probabilities
and heat indices are at:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml