797
FXUS06 KWBC 212002
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EST Fri February 21 2025

6-10 DAY OUTLOOK FOR FEB 27 - MAR 03, 2025

Today`s numerical models depict a fairly amplified 500-hPa flow pattern across
North America and vicinity. The period begins with a positive North Atlantic
Oscillation (NAO) and associated negative height anomalies centered over the
Davis Strait and corresponding positive anomalies over much of the mid-latitude
Atlantic. However, despite the positive NAO, the Pacific North American (PNA)
pattern is also expected to be positive (particularly early in the period).
This positive PNA supports enhanced troughing over the southeastern CONUS and
upstream ridging over much of the western CONUS into southeastern Canada. As
time progresses, the magnitudes of both the NAO and PNA are forecast to
diminish, leading to a more zonal pattern across the CONUS. However, the
opposite is true for Alaska as an amplified pattern is expected to remain in
place throughout the period. A strong trough forecast near the eastern
Aleutians early in the period is forecast to retrograde, allowing enhanced
ridging to dominate most of Alaska by day 10. Positive mid-level height
anomalies are forecast for Hawaii, well to the south of the predicted trough
forecast over the northern Pacific Ocean.

Above normal temperatures are likely to dominate most of western North America,
consistent with the predicted positive PNA early in the period. Anomalous
warmth is likely to overspread much of Alaska (particularly later in the
period) as strong ridging retrogrades from western Canada and builds across the
state. Conversely below normal temperatures are favored across much of the East
as a trough pivots across the region. Above normal temperatures are likely
across Hawaii underneath predicted above normal mid-level heights and due to
anticipated above normal sea surface temperatures (SSTs) in adjacent waters.

Enhanced moisture flow from the Pacific is expected across much of Alaska early
in the period associated with a surface low centered south of the eastern
Aleutians. Therefore, above normal precipitation is favored for much of
southern and western Alaska. The precipitation across Alaska is expected to be
front loaded as a strong ridge is expected to build across the state later in
the period, leading to a drying trend. A complex precipitation pattern is
forecast for the western CONUS as large scale ridging favors below normal
precipitation for much of the Pacific Northwest eastward to parts of the Great
Basin. However, models are predicting a cutoff low to potentially form over the
eastern Pacific and move onshore over the southwestern CONUS, reducing
probabilities of below normal precipitation relative to yesterday. The
precipitation pattern is also expected to be complex across the East due to the
predicted mean trough across the area. There is the potential for a coastal low
near the East Coast ahead of the mean trough axis at the beginning of the
period. For this reason, above normal precipitation is favored along parts of
the Eastern Seaboard with the caveat that uncertainty still exists as to how
close to the coast this storm will form. As this storm departs, a second area
of precipitation may develop across the Southern Plains associated with a
predicted surface low and associated enhanced moisture advection from the Gulf.
Elsewhere, below normal precipitation is favored for most of the east-central
CONUS centered near the confluence of the Ohio and Mississippi Valleys due to
predicted surface high pressure. However, models are indicating the potential
for surface low pressure development for parts of the Upper Mississippi Valley
and Great Lakes underneath mean cyclonic mid-level flow. This shortwave trough
weakly enhances probabilities of above normal precipitation across much of the
northern tier of the CONUS. Conversely, drier than normal weather is likely
across eastern Hawaii due to predicted ridging. A slight tilt toward above
normal precipitation is indicated for Kauai, Niihau, and Oahu based on a skill
weighted consolidation of calibrated GEFS and ECMWF ensemble precipitation
amounts.

The official 6-10 day 500-hPa height blend consists of 30% of Today`s 6z GFS
Ensemble Mean centered on Day 8, 50% of Today`s 0z European Ensemble Mean
centered on Day 8, and 20% of Today`s 0z Canadian Ensemble Mean centered on Day
8


FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: Average, 3 out of 5, due to fairly
good model agreement offset by inherent increased uncertainties associated with
a predicted complex 500-hPa flow pattern evolution.

8-14 DAY OUTLOOK FOR MAR 01 - 07 2025

During week-2, the PNA is forecast to switch to the negative phase and the
positive NAO is expected to continue to weaken. In general, troughing is
forecast to persist across much of the eastern CONUS. However, with the
positive PNA expected to shift to the negative phase, the southern extent of
this troughing is in question. Periods of ridging may begin to develop across
parts of the Southeast, particularly later in the period associated with the
transition of the PNA. Across the West, with the PNA expected to rapidly
transition, the chances of a significant pattern change increases. Ridging
forecast early in the period is predicted to quickly break down with periods of
troughing and below normal heights emerging by the middle of the period, and
the end result favoring near normal heights for the period as a whole. The
increased ridging forecast across Alaska late in the 6-10 day period is
expected to persist throughout the remainder of the week-2 period, resulting in
above normal mean mid-level heights across the vast majority of the state.
Height anomalies are generally forecast to weaken across Hawaii with nominally
above normal heights predicted for the period as a whole across the state.

Above normal temperatures are likely across Alaska as a strong ridge is
forecast to persist throughout the period. The story is different for the
western CONUS as ridging early in the period is forecast to rapidly weaken. As
a result the coverage and magnitude of above normal probabilities are reduced
relative to yesterday. Residual weakly enhanced probabilities of above normal
temperatures are indicated for the Southwest, southern Great Basin, southern
and central Rockies, and parts of the southern High Plains due to predicted
ridging early in the period. Below normal temperatures are favored for most of
the CONUS from the Mississippi Valley eastward due to persistent troughing.
However, with the potential transition from a positive to a negative PNA, some
weak ridging is possible for the extreme Southeast, particularly later in the
period. For this reason, near normal temperatures are favored for this region
despite the large scale trough forecast over eastern North America. Conversely,
chances for below normal temperatures are increased farther to the west across
portions of the Upper Mississippi Valley and eastern portions of the Northern
Plains as teleconnections from the strong ridge in Alaska support cold air
intrusions in the north-central CONUS. On the flip side, Hawaii is likely to
experience above normal temperatures, due, in part, to anticipated above normal
SSTs in adjacent waters coupled with predicted slightly above normal mid-level
heights.

Due to the predicted transitional pattern, the precipitation forecast is highly
uncertain across most of the country. Correspondingly, probabilities of either
above or below normal precipitation do not exceed 50 percent anywhere in the
nation. Above normal precipitation is favored around the periphery of a mean
trough forecast over eastern North America. Probabilities of above normal
precipitation exceed 40 percent for parts of the Lower Mississippi Valley and
Gulf Coast region due to the potential northward advection of moisture from
adjacent waters. Probabilities of above normal precipitation also exceed 40
percent for the northern and central High Plains due to the potential for
upslope flow. A slight tilt toward below normal precipitation is indicated for
Southeast Alaska southward to parts of the Pacific Northwest ahead of a mean
ridge axis predicted over eastern Alaska. Slightly increased odds of above
normal precipitation are indicated for western Mainland Alaska and the
Aleutians behind this ridge axis. Below normal precipitation is weakly favored
for eastern Hawaii underneath predicted slightly above normal 500-hPa heights.
A slight tilt toward above normal precipitation is indicated for Kauai and
Niihau based on a skill weighted consolidation of calibrated GEFS and ECMWF
ensemble precipitation amounts.

The official 8-14 day 500-hPa height blend consists of: 25% of Today`s 6z GFS
Ensemble Mean centered on Day 11, 50% of Today`s 0z European Ensemble Mean
centered on Day 11, and 25% of Today`s 0z Canadian Ensemble Mean centered on
Day 11


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: Below Average, 2 out of 5, due to
a predicted transitional pattern across much of the Lower 48 states.

FORECASTER: Scott H

Notes:


Automated forecasts are issued on Saturday and Sunday. Occasionally manual
intervention is necessary to address quality control and consistency issues. In
these cases, forecasts are manually drawn but a full discussion is not issued.


The notation for the categorical forecast indicated on the maps is the same as
that in the tables: A-above   N-near normal   B-below


The temperature map shows regions with > 33% chance of being warmer (orange,
"A"), colder (blue, "B"), or close to (unshaded, "N"). Historical average
values for the calendar period of the forecast (dashes, "f").  Labels on the
shaded lines give the probability (> 33%) of the more likely category (B or A).
 Probability of N is always < 40%.


The precipitation map shows regions with > 33% chance of being wetter (green,
"A"), drier (tan, "B"), or close to (unshaded, "n"). Historical median values
for the calendar period of the forecast (dashes, "inches").  Labels on the
shaded lines give the probability (> 33%) of the more likely category (B or A).
 Probability of N is always < 40%.


In the southwest and other climatologically dry regions - there will be a
greater than 33.3% chance of no precipitation and occasionally even a normal
(i.e. Median) value of zero - especially during the dry seasons.  In such cases
a forecast of near normal is effectively a forecast of little or no
precipitation.


The climate prediction center uses 1991-2020 base period means as reference in
the climate outlooks.

The next set of long-lead monthly and seasonal outlooks will be released on
March 20.


Analogs to the 5 day mean observed pattern centered 3 days ago (D-3)
for the region from 20N to 70N latitude and 175E to 60W longitude
include the 5 day periods centered on the following dates:
20070213 - 19800208 - 19980302 - 19770214 - 20010306


Analogs to the 7 day mean observed pattern centered 4 days ago (D-4)
for the region from 20N to 70N latitude and 175E to 60W longitude
include the 7 day periods centered on the following dates:
19800207 - 19530210 - 19980301 - 20070212 - 20010306


6-10 DAY OUTLOOK TABLE
Outlook for Feb 27 - Mar 03, 2025

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  A    B     OREGON      A    B     NRN CALIF   A    N
SRN CALIF   A    N     IDAHO       A    B     NEVADA      A    N
W MONTANA   A    A     E MONTANA   A    A     WYOMING     A    N
UTAH        A    N     ARIZONA     A    N     COLORADO    A    N
NEW MEXICO  A    N     N DAKOTA    A    A     S DAKOTA    A    N
NEBRASKA    A    N     KANSAS      A    N     OKLAHOMA    N    N
N TEXAS     N    A     S TEXAS     N    A     W TEXAS     A    A
MINNESOTA   N    N     IOWA        N    B     MISSOURI    N    B
ARKANSAS    N    B     LOUISIANA   N    N     WISCONSIN   N    N
ILLINOIS    N    B     MISSISSIPPI N    B     MICHIGAN    B    N
INDIANA     B    B     OHIO        B    N     KENTUCKY    B    B
TENNESSEE   B    B     ALABAMA     N    B     NEW YORK    B    A
VERMONT     B    A     NEW HAMP    B    A     MAINE       B    A
MASS        B    A     CONN        B    A     RHODE IS    B    A
PENN        B    A     NEW JERSEY  B    A     W VIRGINIA  B    N
MARYLAND    B    A     DELAWARE    N    A     VIRGINIA    B    N
N CAROLINA  N    N     S CAROLINA  B    N     GEORGIA     B    N
FL PNHDL    B    N     FL PENIN    B    A     AK N SLOPE  A    N
AK ALEUTIAN A    A     AK WESTERN  A    A     AK INT BSN  A    A
AK S INT    A    A     AK SO COAST A    A     AK PNHDL    A    A



8-14 DAY OUTLOOK TABLE
Outlook for Mar 01 - 07 2025

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  N    N     OREGON      N    N     NRN CALIF   N    N
SRN CALIF   A    N     IDAHO       N    N     NEVADA      A    N
W MONTANA   N    A     E MONTANA   N    A     WYOMING     N    A
UTAH        A    A     ARIZONA     A    N     COLORADO    A    A
NEW MEXICO  A    A     N DAKOTA    N    N     S DAKOTA    N    A
NEBRASKA    N    A     KANSAS      N    A     OKLAHOMA    N    A
N TEXAS     N    A     S TEXAS     N    A     W TEXAS     A    A
MINNESOTA   B    N     IOWA        B    N     MISSOURI    B    N
ARKANSAS    N    A     LOUISIANA   N    A     WISCONSIN   B    N
ILLINOIS    B    N     MISSISSIPPI N    A     MICHIGAN    B    N
INDIANA     B    N     OHIO        B    N     KENTUCKY    B    A
TENNESSEE   B    A     ALABAMA     B    A     NEW YORK    B    N
VERMONT     B    N     NEW HAMP    B    A     MAINE       B    A
MASS        B    A     CONN        B    A     RHODE IS    B    A
PENN        B    N     NEW JERSEY  B    A     W VIRGINIA  B    A
MARYLAND    B    A     DELAWARE    B    A     VIRGINIA    B    A
N CAROLINA  B    A     S CAROLINA  B    A     GEORGIA     B    A
FL PNHDL    N    A     FL PENIN    N    N     AK N SLOPE  A    N
AK ALEUTIAN A    A     AK WESTERN  A    A     AK INT BSN  A    N
AK S INT    A    N     AK SO COAST A    N     AK PNHDL    A    B

                           LEGEND
TEMPS WITH RESPECT TO NORMAL     PCPN WITH RESPECT TO MEDIAN
A - ABOVE   N  - NEAR NORMAL     A - ABOVE   N - NEAR MEDIAN
B - BELOW                        B - BELOW

THE FORECAST CLASSES REPRESENT AVERAGES FOR EACH STATE. NORMAL
VALUES - WHICH MAY VARY WIDELY ACROSS SOME STATES - ARE
AVAILABLE FROM YOUR LOCAL WEATHER SERVICE FORECAST OFFICE.

FOR ADDITIONAL INFORMATION SEE MESSAGE FXUS06 KWBC - ON AWIPS AS
PMDMRD.

$$