Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
341 PM EDT Thu Oct 06 2022

Valid 00Z Fri Oct 07 2022 - 00Z Sun Oct 09 2022

...Temperatures plunging across the Central U.S. as strong cold front
pushes southward...

...Much improved conditions in the Northeast through Friday before cooler
air filters in behind cold front...

...Daily showers and thunderstorms continue for the Southern Rockies/High
Plains and the Southwest, with isolated instances of flash flooding
possible...

...Pleasant weather across much of the West through the end of the week...

The main story through Saturday will be the potent cold front moving
southward across central and eastern CONUS, with temperatures plunging as
unseasonably cold air filters in from Canada. Highs today across the
northern Plains will struggle to reach the 50-degree mark behind the
frontal boundary, with temperatures dipping below freezing tonight,
leading to the issuance of Freeze Warnings and Freeze Watches across the
Dakotas. Isolated areas in North Dakota may even see temperatures as low
as the upper teens on Friday morning. In addition to the frigid air,
breezy conditions will follow with the passage of the front and gusts may
reach 20-30 miles per hour. Lake-effect showers are also in the forecast
for the Upper Great Lakes as a result of the cold, northwest flow across
the warmer lake water. Some wet snow may mix in for higher elevations of
Wisconsin and the Upper Peninsula of Michigan on Thursday night, though no
accumulation is expected. Below-average temperatures will continue
spreading south on Friday, with highs in the 50s and low-60s as far south
as the southern Plains and Mississippi Valley. Highs will remain even
cooler to the north as a strong Canadian high presses southward, with
mid-to-upper 40s expected for the Upper Midwest and Great Lakes. Lows near
freezing are again possible on Saturday morning for the Great Lakes Region
and Upper Mississippi Valley, with temperatures beginning to rebound
across the northern Plains as more seasonable highs in the low 60s return.

Beautiful weather is in store for the Northeast and Mid-Atlantic through
Saturday, as the upper-level low that brought dreary conditions this past
week has finally slid well offshore. Sunny skies, dry conditions, and
seasonable temperatures in the low-to-mid 70s for highs are expected
through Friday throughout the region, with highs slightly warmer in the
upper 70s to mid-80s across the Southeast and Florida. The warm-up will be
short-lived, as the aforementioned potent cold front makes its way through
the region Friday evening, bringing cooler, fall-like temperatures in its
wake, with highs in the mid-to-upper 60s expected on Saturday. Unlike this
past week, the unseasonably cool air will not be accompanied by wet and
cloudy conditions, with dry weather following in its wake and providing
residents in the Northeast with the perfect weather to view the emergence
of fall foliage in interior New England.

Similarly to the Northeast, pleasant conditions will continue across the
Pacific Northwest, California, and the Great Basin through Saturday as an
upper-level ridge remains in place over the region. Highs are forecast to
remain in the upper 70s and low 80s for the Pacific Northwest and Great
Basin, lower 90s for the central California Valleys, low to mid-70s along
the California coast, and mid-90s to near 100 for the Desert Southwest.
Moreover, conditions will remain dry during this span, resulting in
overall pleasant conditions through the end of the week.

Further south, daily showers and thunderstorms will continue across the
Southern Rockies and Southwest on the east side of a lingering upper-level
low drifting over the Southwest. Anomalously high moisture that remains
pooled across the area will help enhance storm rainfall rates and totals,
and isolated instances of flash flooding are possible, particularly for
areas of sensitive terrain and across burn scars. As a result, a Marginal
Risk of Excessive Rainfall has been issued for much of Arizona and New
Mexico through Saturday. High temperatures will remain below normal with
mid-60s to low 70s expected.


Russell

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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
441 PM EDT Thu Oct 06 2022

Valid 12Z Sun Oct 09 2022 - 12Z Thu Oct 13 2022

...Overview...

Next week looks to start out with an amplified pattern, with upper
troughing over the east-central U.S. and a Canadian surface high
creating a cool and dry airmass. Meanwhile an eastern Pacific
upper high will extend general ridging into the West, save for a
shortwave in the Northwest and another in northern
Mexico/southwestern U.S. that should cause continued showers
there. The overall pattern becomes more uncertain after energy
digs into the western U.S. Tuesday, with model guidance waffling
on the evolution of this energy into midweek and beyond. But the
current forecast shows troughing progressing into the
north-central U.S. with a reasonably strong cold front ahead of it
as well as rain chances, while a southern stream upper low may
spin into the Great Basin.


...Guidance Evaluation/Predictability Assessment...

Model guidance has been and continues to be persistent in showing
troughing with its axis across the eastern U.S. early next week.
The 00Z UKMET was perhaps a bit of an outlier with the timing of a
shortwave within this trough. Models also show good consensus with
the general ridge pattern centered in the eastern Pacific and
extending into the West Coast, along with better agreement for a
shortwave in the Northwest Sun and weak energy over northern
Mexico opening into a trough. Thus the early part of the medium
range period fronts/pressures forecast was based on a blend of the
00/06Z GFS and 00Z ECMWF and CMC along with a bit of continuity.

By Tuesday-Thursday, models have shown considerable changes over
the past couple of days with the eventual evolution of potent
energy coming into the West. This energy stems from Siberia into
the Bering Sea during the short range period, so considering this
tends to be an uncertain area for models, more forecast changes
may continue over the next few days. After yesterday's guidance
indicated a strong upper low was likely to form in the West as
most energy dove southward, for the most part the 00Z/06Z model
cycle and newer 12Z model cycle shows more of the energy remaining
in the northern stream and tracking a trough eastward. The CMC
runs have stuck with a closed low type solution, however. Some
ECMWF/GFS runs do show a weaker southern stream closed low forming
by Wed or Thu, with perhaps some energy tracking south but the
aforementioned Northwest shortwave also looks to play a role in
forming the low. Thus the WPC forecast trended weaker with the
upper low in the West, with a combination of the deterministic
models and ensemble means in the forecast blend, and continuing to
include some continuity in the forecast blend as well for
potential that models could change back. For QPF, this also led to
a drier solution than continuity across the Intermountain West per
model trends, but wetter and more broad than the 13Z NBM was, as a
middle ground.


...Weather/Hazards Highlights...

The combination of persistent monsoonal moisture and an upper low
evolving into a trough over northwest Mexico will continue to fuel
diurnal showers and thunderstorms over parts of the Desert
Southwest/southern Rockies through early next week, with the
greatest rainfall totals expected for central and southern New
Mexico based on latest model guidance. Moisture could stream into
the Southern Plains and produce some showers and thunderstorms
there as well. Then a strong cold front associated with the
western to central U.S. trough will produce rain and potentially
some high elevation snow for the northern Rockies around
Tuesday-Wednesday, and then moisture and thus rain chances spread
into the central U.S. to Midwest/Great Lakes. Elsewhere, light to
locally moderate rainfall should spread northward over the Florida
Peninsula as easterly low level flow strengthens behind a front.

Much of the northwestern U.S. should see above normal temperatures
at least through Monday with highs 10 to locally 20F above normal.
Recent forecasts show the Pacific Northwest may stay warmer than
normal through the week as well if troughing evolves by staying to
its east, but areas across the Great Basin/Rockies are likely to
cool down, followed by the central U.S. behind a cold front. Highs
look to be around 5-10F below normal for those areas, with lows
closer to normal. But these forecasts could change as the pattern
hopefully becomes clearer with time. The East is likely to start
next week with cooler than normal weather and moderate to near
normal as the week progresses.


Tate

Hazards:
- Much below normal temperatures across portions of the
Mid-Atlantic, the Lower Mississippi Valley, the Central
Appalachians, the Tennessee Valley, the Middle Mississippi Valley,
the Northeast, the Southern Appalachians, the Upper Mississippi
Valley, the Southeast, the Great Lakes, and the Ohio Valley, Sun,
Oct 9.

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, experimental excessive rainfall
outlook, 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/#page=ero
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
116 AM EDT Thu Oct 6 2022

Valid 00Z Fri Oct 7 2022 - 00Z Fri Oct 14 2022

An anomalous, deep closed low will slowly drift southward from the
Gulf of Alaska and reaching the general vicinity of 35-40 degrees
north by Saturday, and then remaining quasi-stationary through
about Tuesday as it remains stuck behind a ridge axis to its east.
The trailing stationary front should be close enough to the state
to generate some additional showers and storms for the central and
northern Islands, although the heaviest rain should still be
across the windward terrain of the Big Island.

The overall model consensus for early next week is for the upper
low to linger through early Tuesday before eventually getting
absorbed by an amplifying trough to its northwest. The ensemble
means are suggesting another closed upper low/trough will likely
develop northwest of the state by next Wednesday/Thursday as the
blocking ridge just off the West Coast of the U.S. remains
anchored in place. In terms of trade winds, the general col in
the surface high and the proximity of the front will tend to
result in lighter winds than normal for most of the upcoming week
and more of a southeasterly component at times.

Hamrick

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
718 PM EDT Thu Oct 06 2022

Day 1
Valid 01Z Fri Oct 07 2022 - 12Z Fri Oct 07 2022

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL ACROSS PARTS OF
NEW MEXICO AND ARIZONA...

...01Z Outlook Update...
The ongoing forecast is basically on track...although a cluster of
storms along the international border with California and Arizona
has developed into an excessive rainfall threat given cell
training. Expanded the Marginal Risk area to account for
that...although the excessive threat should diminish fairly
quickly by 03Z or so. Still think that the overall potential is
for isolated/spotty flash flooding...with decreasing thunderstorm
coverage/intensity increases with the loss of daytime heating. The
prior discussion below provides additional details on the Marginal
flash flood risk today.

Bann

...Previous discussion...

Model guidance has been trending the convective potential westward
for several runs across Arizona while varying in the exact
placement of the mid/upper level features and the subsequent QPF.
The surface frontal boundary is expected to slow and because
quasi-stationary across southern portions of the Southwest and
across central Texas as the northern stream begins to to pull away
from the upper low/trough over the Southwest. Any of these storms
will have the potential to produce locally heavy rainfall that
could cause excessive runoff in a few areas - especially during
and just after peak heating hours. A Marginal Risk area is in
effect across across Arizona, New Mexico and extreme western Texas.

Campbell

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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
345 PM EDT Thu Oct 06 2022

Day 2
Valid 12Z Fri Oct 07 2022 - 12Z Sat Oct 08 2022


...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL ACROSS PARTS OF
SOUTHWEST...

...21Z Outlook Update...

The ongoing forecast is on track. The main drivers for locally
heavy rainfall will include a nearly stationary upper low over
northwestern Mexico and a strong front that should trend toward
stationary movement while approaching the Front Range late in the
forecast period. Diurnally driven storms should form across the
Marginal area, posing an isolated flash flood risk.

Cook

...Previous Discussion...

The leading frontal boundary will once again progress southward,
reaching the Gulf by the end of the this period. Behind it,
building high pressure over the central states will send a
weakening secondary cold front southward and westward against the
Front Range, which will hang up near the Southern Rockies and
Southern Plains. Diurnally driven showers and thunderstorms within
the deep pooled moisture will persist across many of the same
locations across the Southwest, but also, extending into portions
of Colorado and the Oklahoma and Texas Panhandles. This
convective activity has the potential for isolated flash flooding.
A Marginal Risk area for excessive rainfall was raised from
Southeast Arizona to much of New Mexico and small portions of
western Texas.

Campbell

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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
349 PM EDT Thu Oct 06 2022

Day 3
Valid 12Z Sat Oct 08 2022 - 12Z Sun Oct 09 2022


...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL ACROSS PARTS OF
SOUTHWEST...

...21Z Outlook Update...
Mid-level troughing will continue across northwestern Mexico,
fostering thunderstorm development during the afternoon and early
evening. The Marginal risk of flash flooding will continue in
this regime. More information is available in the previous
discussion below.

Cook

...Previous Discussion...

Convective activity is expected across the Southwest as mid/upper
level features continue to drift westward. Abundant moisture will
still be available to help fuel diurnally driven showers and
thunderstorms over the region. There may be durations of locally
heavy rainfall that lead to an isolated instances of flash
flooding and runoff. Given the westward drifting a Marginal Risk
area was hoisted over much of the Southwest, southern Colorado and
a small portion of California near the Arizona border.

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
441 PM EDT Thu Oct 06 2022

Valid 00Z Fri Oct 07 2022 - 00Z Mon Oct 10 2022

The probabilitiy of at least 4 inches of snow is less than 10
percent.

The probability of significant icing is less than 10 percent.

Fracasso

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
441 PM EDT Thu Oct 06 2022

Valid 12Z Sun Oct 09 2022 - 12Z Thu Oct 13 2022

...Overview...

Next week looks to start out with an amplified pattern, with upper
troughing over the east-central U.S. and a Canadian surface high
creating a cool and dry airmass. Meanwhile an eastern Pacific
upper high will extend general ridging into the West, save for a
shortwave in the Northwest and another in northern
Mexico/southwestern U.S. that should cause continued showers
there. The overall pattern becomes more uncertain after energy
digs into the western U.S. Tuesday, with model guidance waffling
on the evolution of this energy into midweek and beyond. But the
current forecast shows troughing progressing into the
north-central U.S. with a reasonably strong cold front ahead of it
as well as rain chances, while a southern stream upper low may
spin into the Great Basin.


...Guidance Evaluation/Predictability Assessment...

Model guidance has been and continues to be persistent in showing
troughing with its axis across the eastern U.S. early next week.
The 00Z UKMET was perhaps a bit of an outlier with the timing of a
shortwave within this trough. Models also show good consensus with
the general ridge pattern centered in the eastern Pacific and
extending into the West Coast, along with better agreement for a
shortwave in the Northwest Sun and weak energy over northern
Mexico opening into a trough. Thus the early part of the medium
range period fronts/pressures forecast was based on a blend of the
00/06Z GFS and 00Z ECMWF and CMC along with a bit of continuity.

By Tuesday-Thursday, models have shown considerable changes over
the past couple of days with the eventual evolution of potent
energy coming into the West. This energy stems from Siberia into
the Bering Sea during the short range period, so considering this
tends to be an uncertain area for models, more forecast changes
may continue over the next few days. After yesterday's guidance
indicated a strong upper low was likely to form in the West as
most energy dove southward, for the most part the 00Z/06Z model
cycle and newer 12Z model cycle shows more of the energy remaining
in the northern stream and tracking a trough eastward. The CMC
runs have stuck with a closed low type solution, however. Some
ECMWF/GFS runs do show a weaker southern stream closed low forming
by Wed or Thu, with perhaps some energy tracking south but the
aforementioned Northwest shortwave also looks to play a role in
forming the low. Thus the WPC forecast trended weaker with the
upper low in the West, with a combination of the deterministic
models and ensemble means in the forecast blend, and continuing to
include some continuity in the forecast blend as well for
potential that models could change back. For QPF, this also led to
a drier solution than continuity across the Intermountain West per
model trends, but wetter and more broad than the 13Z NBM was, as a
middle ground.


...Weather/Hazards Highlights...

The combination of persistent monsoonal moisture and an upper low
evolving into a trough over northwest Mexico will continue to fuel
diurnal showers and thunderstorms over parts of the Desert
Southwest/southern Rockies through early next week, with the
greatest rainfall totals expected for central and southern New
Mexico based on latest model guidance. Moisture could stream into
the Southern Plains and produce some showers and thunderstorms
there as well. Then a strong cold front associated with the
western to central U.S. trough will produce rain and potentially
some high elevation snow for the northern Rockies around
Tuesday-Wednesday, and then moisture and thus rain chances spread
into the central U.S. to Midwest/Great Lakes. Elsewhere, light to
locally moderate rainfall should spread northward over the Florida
Peninsula as easterly low level flow strengthens behind a front.

Much of the northwestern U.S. should see above normal temperatures
at least through Monday with highs 10 to locally 20F above normal.
Recent forecasts show the Pacific Northwest may stay warmer than
normal through the week as well if troughing evolves by staying to
its east, but areas across the Great Basin/Rockies are likely to
cool down, followed by the central U.S. behind a cold front. Highs
look to be around 5-10F below normal for those areas, with lows
closer to normal. But these forecasts could change as the pattern
hopefully becomes clearer with time. The East is likely to start
next week with cooler than normal weather and moderate to near
normal as the week progresses.


Tate

Hazards:
- Much below normal temperatures across portions of the
Mid-Atlantic, the Lower Mississippi Valley, the Central
Appalachians, the Tennessee Valley, the Middle Mississippi Valley,
the Northeast, the Southern Appalachians, the Upper Mississippi
Valley, the Southeast, the Great Lakes, and the Ohio Valley, Sun,
Oct 9.

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, experimental excessive rainfall
outlook, 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/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml