633
FXUS06 KWBC 112002
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EST Tue February 11 2025

6-10 DAY OUTLOOK FOR FEB 17 - 21 2025

Model means are in good agreement and very similar to yesterday, showing a
pattern of anomalously high 500-hPa heights across the Arctic region extending
southward into most of Greenland and roughly the north half of central and
eastern Canada. These positive anomalies extend across Alaska and southward
through western North America as a mid-level ridge prevails in this region.
There is an area of relatively low heights just northwest of Mainland Alaska
which was not depicted in the models yesterday, but model solutions continue to
show a nearly full-latitude mid-level ridge from most of Mainland Alaska
southward, with an axis along or just west of the CONUS Far West. Meanwhile,
south of the strong positive anomalies over much of central and eastern Canada,
anomalously low mean 500-hPa heights reach from the southern tier of central
and eastern Canada southward into the central and eastern CONUS and eastward
into the North Atlantic. Near to slightly above normal mid-level heights are
anticipated farther south along or near the extreme southern tier of the CONUS.
Most models extend subnormal mid-level heights a little farther south than
yesterday, to along the Gulf Coast or farther south. The exception is the
Canadian ensemble mean, which keeps negative height anomalies slightly farther
north in the Deep South.

In concert with the abnormally low heights, below-normal temperatures are
favored over most of the central and eastern CONUS. Near and above normal
temperature forecasts reach a bit farther south in Florida than yesterday due
to the lower mid-level heights forecast. Significantly below-normal
temperatures are most likely from portions of the Middle Mississippi Valley
eastward through most of the Great Lakes, Ohio Valley, and Northeast, where
chances exceed 80%. Odds for cold weather decrease to the south and east, where
the cold air mass will arrive later in the period, which is also consistent
with 500-hPa heights closer to normal. Meanwhile, with a building mid-level
ridge in the western CONUS, temperatures should be rising there during the
period. The reforecasts take the warmth considerably farther north and west
than the raw and bias-corrected model output in the West. For now, less warmth
in the Northwest is the favored solution given the inherent uncertainties of a
transitional regime. There are enhanced odds for warmth in the Southwest, as
indicated by almost all tools.

With building mid-level heights, odds for unusual warmth are a bit higher today
across southern and portions of eastern Alaska. Subnormal readings are slightly
favored in northwestern Alaska near the area of relatively low 500-hPa heights.
Meanwhile, above-normal temperatures are strongly favored across Hawaii, with
odds for significantly above-normal temperatures exceeding 70 percent statewide
and topping 80 percent in central areas from central Oahu through central Maui,
including Molokai and Lanai.

One or more mid-level waves of low pressure are expected to move along the
southern tier of the subnormal 500-hPa heights over the central and eastern
CONUS, increasing the odds for heavy precipitation across the Southeast,
mid-Atlantic region, and coastal Northeast. A storm moving through at the end
of week-1 will allow the 6- to 10-day period to start out dry in these areas
before another storm forms and moves through the southeastern and eastern CONUS
later. With this storm expected to track a little farther south and east than
yesterday, and with the first system no longer expected to affect the region
during this period, odds for surplus precipitation are relatively modest, and
chances exceeding 40% are limited to the southeastern CONUS from portions of
the Lower Mississippi Valley through the South Atlantic States. To the
northwest of the storm track, there are slightly enhanced chances for drier
than normal conditions from the northern Upper Mississippi Valley and adjacent
Great Plains through the Great Lakes region. Farther west, there are elevated
chances for above-normal precipitation over the Northwest, the northern and
eastern Rockies, and most of the Plains, where a mid-level disturbance is
expected to traverse the region (this is expected to help fuel the storm in the
Southeast later in the period. Meanwhile, drier than normal weather is expected
over the Southwest and some adjacent areas under above-normal mid-level heights
and downstream from the building ridge.

Meanwhile, broad mean southwesterly surface flow should bring above-normal
precipitation into the southern tier of Alaska, although the uncertainty of a
transitioning regime keeps the odds relatively low. Farther north, after
moisture gets orographically wrung-out of the southwesterly surface flow,
precipitation is expected to be closer to normal. Over Hawaii, precipitation
should gradually decrease as the period progresses, and the sum totals for the
period are not anticipated to range far from normal.

The official 6-10 day 500-hPa height blend consists of 20% of Today`s GFS
Superensemble Mean centered on Day 8, 10% of Today`s operational 6z GFS
centered on Day 8, 25% of Today`s 0z European Ensemble Mean centered on Day 8,
15% of Today`s operational 0z ECMWF centered on Day 8, and 30% of Today`s 0z
Canadian Ensemble Mean centered on Day 8


FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: Somewhat above normal, 4 out of 5,
for good agreement in the overall mean pattern and day-to-day consistency, with
uncertainty introduced by the transitional nature of the regime in western
North America and some disagreements between the reforecast temperatures and
the bias-corrected and raw output from the ensembles.

8-14 DAY OUTLOOK FOR FEB 19 - 25 2025

During week-2, the general mean pattern should be similar to the 6- to 10-day
period, featuring above-normal 500-hPa heights over the Arctic and across
western North America, subnormal mid-level heights across the central and
eastern CONUS outside the Southern Tier, and a full-latitude ridge over or near
western North America. The Canadian ensemble mean maintains slightly above
normal 500-hPa heights across the Gulf Coast States, but the preponderance of
guidance keeps heights slightly below normal there, and this is the preferred
solution. As the period progresses, short waves moving through the mean flow
seem to deamplify the pattern, but the set-up is reloaded by the end of the
period. So the pattern for the week-2 period ends about the same as it began;
the primary exception is over the North Pacific, where below-normal 500-hPa
heights expand eastward toward the Gulf of Alaska by the end of the period, and
this pushes the ridge position slightly farther east in western North America
than the 6- to 10-day mean. As a result, above-normal mean 500-hPa heights
expand eastward through the High Plains in the manual blend. This evolution of
events results in a mean pattern a bit more amplified than indicated yesterday,
which is consistent with yesterdays forecast reasoning. The European ensemble
mean continues to depict a bit more amplification than the other ensemble
means, but all solutions result in a similar pattern of sensible weather across
the hemisphere. Inconsistencies in the timing and amplitude of individual
systems remain, as would be expected at this time range, but there is better
model agreement overall than yesterday.

This pattern favors continued colder than normal weather over the central and
eastern CONUS, with modified Canadian air pushing southward through the entire
Florida Peninsula for much of week-2. Odds for abnormally low temperatures
exceed 70% over the Ohio Valley and mid-Atlantic region. Meanwhile, the
prevailing full-latitude mid-level ridge farther west favors above-normal
temperatures over the southwestern quarter of the country and, to a lesser
extent, the Pacific Northwest.

The full-latitude ridge should extend into eastern Alaska, favoring
above-normal temperatures everywhere outside the northwestern Mainland, where
mid-level heights should remain closer to normal. Chances for significant
warmth exceed 60% in parts of southern and southeastern Alaska. The
Consolidation continues to strongly favor above-normal temperatures across
Hawaii during week-2, where most locations have at least a 70% chance of
averaging warmer than usual.

Most models agree that a storm system should be affecting part of the eastern
CONUS as the period begins. Thereafter, the European ensembles favor more
pattern amplification and thus more active weather in the eastern CONUS during
the middle and later parts of week-2 than most other tools, although the models
have come into a little better agreement today. The forecast leans toward the
European ensemble mean, which keeps more unsettled weather in the eastern
CONUS. As a result, above-normal precipitation is favored where indicated by
tools derived from the European ensemble, into the lower Northeast given the
potential for one or more low pressure waves to affect the region. Northwest of
the storm track, slightly increased odds for below-normal precipitation
continue through week-2 in the Great Lakes region. Below-normal precipitation
is also favored in the Southwest and much of the West Coast with the rebuilding
mid-level ridge keeping strong onshore flow farther north. Meanwhile, the
central CONUS evolves into a position downstream from the near-full-latitude
mid-level ridge in western North America and the persistent swath of
below-normal 500-hPa heights farther to the east.
As a result, near- or below-normal precipitation is favored over the Plains and
adjacent areas.

The axis of the strong western North America mid-level ridge should stretch
through northwestern Canada, leaving most of Alaska in cyclonic mid-level flow
downstream from declining 500-hPa heights southwest of the state. This favors
heavy precipitation in most areas, especially in southeastern sections.
Meanwhile, the consolidation forecasts continue to trend slowly toward drier
conditions across Hawaii, and the week-2 forecast slightly favors below-normal
precipitation statewide.

The official 8-14 day 500-hPa height blend consists of: 25% of Today`s GFS
Superensemble Mean centered on Day 11, 35% of Today`s 0z European Ensemble Mean
centered on Day 11, and 40% of Today`s 0z Canadian Ensemble Mean centered on
Day 11


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: Above average, 4 out of 5, with
better model agreement than yesterday, offset slightly by uncertainties in the
evolution of individual short-waves, along with continued inconsistencies among
the derived temperature and precipitation tools.

FORECASTER: Rich Tinker

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
February 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:
19570125 - 19890203 - 19890215 - 19880203 - 19510129


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:
19890203 - 19890215 - 19880202 - 19570127 - 19510127


6-10 DAY OUTLOOK TABLE
Outlook for Feb 17 - 21 2025

STATE      TEMP PCPN   STATE      TEMP PCPN   STATE      TEMP PCPN
WASHINGTON  N    A     OREGON      N    N     NRN CALIF   N    B
SRN CALIF   A    B     IDAHO       B    A     NEVADA      N    B
W MONTANA   B    A     E MONTANA   B    A     WYOMING     B    A
UTAH        N    N     ARIZONA     A    B     COLORADO    B    A
NEW MEXICO  B    N     N DAKOTA    B    N     S DAKOTA    B    A
NEBRASKA    B    A     KANSAS      B    A     OKLAHOMA    B    A
N TEXAS     B    A     S TEXAS     B    A     W TEXAS     B    A
MINNESOTA   B    N     IOWA        B    N     MISSOURI    B    A
ARKANSAS    B    A     LOUISIANA   B    A     WISCONSIN   B    N
ILLINOIS    B    N     MISSISSIPPI B    A     MICHIGAN    B    B
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    N     MAINE       B    N
MASS        B    N     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    B    A     FL PENIN    B    A     AK N SLOPE  B    N
AK ALEUTIAN A    A     AK WESTERN  B    N     AK INT BSN  A    N
AK S INT    A    A     AK SO COAST A    A     AK PNHDL    A    A



8-14 DAY OUTLOOK TABLE
Outlook for Feb 19 - 25 2025

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

                           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.

$$