Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
403 PM EDT Thu Mar 19 2026

Valid 00Z Fri Mar 20 2026 - 00Z Sun Mar 22 2026

...An anomalously early and record-breaking heatwave continues
into the weekend, while expanding eastward into the Southern
Plains...

...A clipper system will bring snowfall to upstate New York and
New England and a chance for locally strong thunderstorms across
the Ohio Valley tomorrow...

...Critical Risk of fire weather is likely Friday and Saturday
from the northern Plains into the Inter-Mountain West...

A strong mid-level ridge is forecast to dominate much of the
weather through the end of the week into the weekend. The Heat
Risk tool continues to indicate threats for widespread Major to
Moderate impacts across California and Arizona. In terms of local
watches and warnings, Extreme Heat Warnings and Heat Advisories
are in effect for the same regions. Expect high temperatures to
challenge and break monthly records for March as the mercury
flirts into the middle and upper 90s across the valleys in
California and into the 100-110 F range for the deserts in Arizona
on Friday and Saturday. Low temperatures will also be quite warm
and provide little relief, relatively for the time of the year,
from the heat as temperatures only fall into the 60s. The heat
dome is expected to shift eastward over the next few days, and
with it, the record breaking heat. The Rockies and the Central and
Southern Plains will see an increase in the quantity of stations
eclipsing potential record March temperatures for Friday and
Saturday. By Saturday, expect maximum temperatures in the middle
to upper 90s across Texas and low to middle 90s as far north as
Nebraska and South Dakota. Moderate Heat Risk impacts will be
possible from these very warm temperatures.

Around the periphery of the heat bubble, a weak frontal system,
otherwise known as a clipper, will move into the Ohio Valley and
the Northeast tomorrow. Areas in New England and upstate New York
are expected to be cold enough for accumulating snow on the order
of 2-5 inches on Friday. Winter Weather Advisories are in effect
as travel could be slippery. On the warmer side of the system,
enough moisture return and upper-level shear could support a
Marginal Risk for severe storms across the eastern Ohio Valley and
the Appalachians. The main threats will be some hail and strong
winds, though a tornado cannot be ruled out, per the Storm
Prediction Center's discussion.

A Critical Risk of fire weather is outlined by SPC for tomorrow
and likely Saturday across the northern Plains westward into the
northern Rockies. This risk is attributed to the anomalous
mid-level ridge anchored across the Southwest U.S.. Warm to hot
temperatures, low relative humidities, and gusty winds will
provide favorable conditions for fire spread. Much of Wyoming and
western South Dakota and Nebraska are under a Red Flag Warning.

A stubborn Atmospheric River along the northern side of the
Western U.S. ridge will maintain locally heavy rainfall over the
Pacific Northwest through Saturday. Expect another 2-3 inches of
rainfall over the next two days, before the storm system begins to
clear the region by Sunday. There is a threat for flooding from
mostly rivers, but continued rainfall over saturated grounds may
still lead to inundation over low-lying regions. As such, a
Marginal Risk for Excessive Rainfall continues into tomorrow.

Wilder


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Thu Mar 19 2026

Valid 12Z Sun Mar 22 2026 - 12Z Thu Mar 26 2026

...Anomalous early season heat wave across the Southwest abating
somewhat early next week but may rebuild midweek...


...Overview...

The medium-range forecast period should feature an anomalous upper
high hovering near the southwestern border of the U.S. while brief
ridging early next week in the eastern U.S. will be replaced by
broad troughing midweek. In the West, stronger ridging appears to
be the current model trend early next week before significant
troughing reaches the Pacific Northwest and advances farther
southeast into the western U.S. from midweek onward.


...Guidance/Predictability Assessment...

Guidance generally shows good agreement on the large scale pattern
evolution over the CONUS through the period, but notable
differences in the details. There remain some timing uncertainties
with a shortwave/surface low pressure system moving from the
Midwest to the Northeast, with the 06z GFS a bit stronger/west with
the system resulting in much higher snow totals across the
interior Northeast. By next week, deterministic guidance continues
to trend towards stronger ridging over the West, which is in
agreement with the ensemble means. Again, the 06z GFS was
flatter/weaker with this ridging as a result of faster/stronger
troughing moving into the Northwest later in the period.

For the WPC 500mb and surface progs, was able to use a blend of
the deterministic guidance the first half of the period. Increased
the weighting of the ensemble means to 60 percent of the blend by
the end of the period to mitigate the smaller scale detail
differences. Did not include the GFS at all in the blend due to
issues described above. Generally, this approach maintained good
continuity with the previous WPC forecast.


...Weather/Hazards Highlights...

The medium-range forecast period will begin on Sunday with the
record-breaking early season heatwave in the western U.S. abating a
bit due to cold air intruding into the northern and central
Plains. Thereafter, more widespread high temperatures 20 to 30+
degrees above normal appear to return over the western U.S. on
Wednesday before a rather strong cold front penetrates inland
through much of the western U.S. and into the northern Plains by
around Thursday. Numerous record high temperatures will likely be
broken once again across the Southwest followed by the southern
Plains.

Across the central Plains to the Midwest, recent model trends are
indicating stronger ridging on Sunday. This translates to a
stronger and farther northward placement of the warm front across
the Midwest and a stronger surge of the cold air down the northern
and central Plains.

Wintry precipitation could affect New England particularly the
interior sections with the passage of the low pressure wave on
Sunday, with the models trending toward a slower ejection of the
wave. This would keep a wintry mix farther inland and rain farther
south across the Mid-Atlantic although the details are far from
certain. There will likely be a brief warm-up for the East Coast
region this weekend ahead of the strong cold front, with highs
expected to be well into the 60s and 70s for many areas. Highs
should return to slightly below normal levels by Monday and Tuesday
as a Canadian surface high builds in from the north.

Across the Pacific Northwest, with the approach of a deep upper
trough early next week, a return of rain and mountain snow is
likely, with Tuesday to Wednesday being the time period of
receiving the heaviest precipitation. Florida could see some
showers and thunderstorms linger near the east coast due to the
cold front becoming stationary in the vicinity.

Santorelli/Kong


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 forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

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
https://www.wpc.ncep.noaa.gov/#page=ovw

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
842 PM EDT Thu Mar 19 2026
Day 1
Valid 01Z Fri Mar 20 2026 - 12Z Fri Mar 20 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
WESTERN WASHINGTON STATE...

...01Z update...

No changes were made for this update with another day of steady,
locally heavy, rainfall expected for western Washington. The 18Z
HREF guidance did not show significant changes from the 12Z or 00Z
cycles. Hourly rainfall is likely to remain below 0.5 inches and
of concern for flash flooding, but an isolated threat will still
exist, with elevated rivers/streams and soil moisture a concern
given antecedent rainfall over the past several days.

Otto/Hurley

...previous discussion follows...

An atmospheric river of moisture and rainfall originating from the
tropics near Hawaii (a.k.a. Pineapple Express) will be directed at
the Olympics and Cascades of western Washington State on Thursday.
The plume will be guided by a large and very anomalously strong
upper level high/ridge over the Southwest, and a series of lows,
both over the Pacific and the Gulf of Alaska. The plume itself will
be anomalous in that the moisture content will be between 3 and 4
sigma above normal for March for western Washington as PWATs exceed
an inch.

Heavy rain will impact much of western Washington through the day
on Thursday. A brief diminishing of the rain is expected through
the first half of Thursday night before a weak wave of low pressure
moves into southern British Columbia, and another round of heavier
rain moves in after midnight. Total rainfall amounts will be in the
2-4 inch range in the Olympics and northern Cascades. This rain
will be on top of already saturated soils from prior rain events,
so much of the new rainfall will quickly convert to runoff.
Isolated flash flooding is probable, especially in urban and
flood-prone areas.

Wegman


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
842 PM EDT Thu Mar 19 2026
Day 2
Valid 12Z Fri Mar 20 2026 - 12Z Sat Mar 21 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
WESTERN WASHINGTON STATE...

19Z Update...
No changes were made to the previous forecast. The 12Z HREF
continues to support an additional 1-2 inches in the Olympics and
the 2-3 inches along the western slopes of the northern Washington
Cascades.

Pereira

Previous discussion...
A weak wave of low pressure will move ashore into Vancouver Island
very early Friday morning. The moisture associated with its
trailing front will continue the heavy rain into western Washington
from overnight Thursday night. The low will dissipate in southern
British Columbia during the day Thursday, but the associated
rainfall will likely continue for much of the day Friday. Once the
center of the low reforms over the Plains in Alberta, the flow will
weaken enough to end any upslope into western Washington, and
ending the rainfall event. Nevertheless, expect an additional 1-2
inches of rain into the Olympics and another 2-3 inches into the
Washington Cascades before the rain ends. Given plentiful earlier
rains from Day 1/Thursday, there is some potential for flooding to
be ongoing at the start of the period. In which case, additional
rainfall could worsen ongoing flooding and/or initiate new
flooding. A Slight Risk upgrade could be needed with future updates
in the northern Cascades.

Wegman


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
842 PM EDT Thu Mar 19 2026
Day 3
Valid 12Z Sat Mar 21 2026 - 12Z Sun Mar 22 2026

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

Pereira

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
303 PM EDT Thu Mar 19 2026

Valid 00Z Fri Mar 20 2026 - 00Z Mon Mar 23 2026

...Upper Great Lakes to the Northeast...
Days 1-3...

Ridge/trough upper pattern over the CONUS will continue to bring
northern stream systems through the Great Lakes into the Northeast
with minor to occasionally modest snowfall. A system over southern
Canada this evening will push through the Great Lakes tonight and
into southern/southeastern Ontario tomorrow. WAA-driven snow and
some light icing is likely over the U.P. of Michigan and into
northern Lower Michigan. As the clipper moves into the Northeast
tomorrow afternoon/evening, snow will fall mostly over the higher
elevations (above 1500ft or so) where WPC probabilities for at
least 4" are >50%, with lesser accumulations to the valley floors
(T-2"). Precipitation should end on Saturday morning.

The next system will slip into northern MN and the western Great
Lakes Saturday afternoon/evening. With a southwest-to-northeast
thermal gradient, some icing is possible once again over
northeastern MN, northern WI, and northern Lower Michigan near the
surface warm front. That system may track a bit farther south,
which could bring in at least some light to modest snow to
northeastern MN into the U.P. of Michigan. There, WPC probabilities
for at least 4 inches of snow are >40% Saturday into very early
Sunday. The system will race eastward and bring another swath of
snow to northern NYS into New England Sunday. Through 00Z/Mon, WPC
probabilities for an additional 4 inches of snow are >30% over the
higher elevations of the northern Adirondacks into the Green/White
Mountains, but the snow will continue beyond this forecast range.


The chances for significant icing across the CONUS is less than 10
percent.

Fracasso

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Thu Mar 19 2026

Valid 12Z Sun Mar 22 2026 - 12Z Thu Mar 26 2026

...Anomalous early season heat wave across the Southwest abating
somewhat early next week but may rebuild midweek...


...Overview...

The medium-range forecast period should feature an anomalous upper
high hovering near the southwestern border of the U.S. while brief
ridging early next week in the eastern U.S. will be replaced by
broad troughing midweek. In the West, stronger ridging appears to
be the current model trend early next week before significant
troughing reaches the Pacific Northwest and advances farther
southeast into the western U.S. from midweek onward.


...Guidance/Predictability Assessment...

Guidance generally shows good agreement on the large scale pattern
evolution over the CONUS through the period, but notable
differences in the details. There remain some timing uncertainties
with a shortwave/surface low pressure system moving from the
Midwest to the Northeast, with the 06z GFS a bit stronger/west with
the system resulting in much higher snow totals across the
interior Northeast. By next week, deterministic guidance continues
to trend towards stronger ridging over the West, which is in
agreement with the ensemble means. Again, the 06z GFS was
flatter/weaker with this ridging as a result of faster/stronger
troughing moving into the Northwest later in the period.

For the WPC 500mb and surface progs, was able to use a blend of
the deterministic guidance the first half of the period. Increased
the weighting of the ensemble means to 60 percent of the blend by
the end of the period to mitigate the smaller scale detail
differences. Did not include the GFS at all in the blend due to
issues described above. Generally, this approach maintained good
continuity with the previous WPC forecast.


...Weather/Hazards Highlights...

The medium-range forecast period will begin on Sunday with the
record-breaking early season heatwave in the western U.S. abating a
bit due to cold air intruding into the northern and central
Plains. Thereafter, more widespread high temperatures 20 to 30+
degrees above normal appear to return over the western U.S. on
Wednesday before a rather strong cold front penetrates inland
through much of the western U.S. and into the northern Plains by
around Thursday. Numerous record high temperatures will likely be
broken once again across the Southwest followed by the southern
Plains.

Across the central Plains to the Midwest, recent model trends are
indicating stronger ridging on Sunday. This translates to a
stronger and farther northward placement of the warm front across
the Midwest and a stronger surge of the cold air down the northern
and central Plains.

Wintry precipitation could affect New England particularly the
interior sections with the passage of the low pressure wave on
Sunday, with the models trending toward a slower ejection of the
wave. This would keep a wintry mix farther inland and rain farther
south across the Mid-Atlantic although the details are far from
certain. There will likely be a brief warm-up for the East Coast
region this weekend ahead of the strong cold front, with highs
expected to be well into the 60s and 70s for many areas. Highs
should return to slightly below normal levels by Monday and Tuesday
as a Canadian surface high builds in from the north.

Across the Pacific Northwest, with the approach of a deep upper
trough early next week, a return of rain and mountain snow is
likely, with Tuesday to Wednesday being the time period of
receiving the heaviest precipitation. Florida could see some
showers and thunderstorms linger near the east coast due to the
cold front becoming stationary in the vicinity.

Santorelli/Kong


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 forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

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
https://www.wpc.ncep.noaa.gov/#page=ovw