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6-10 Day outlooks are issued daily between 3pm & 4pm Eastern Time. All forecasts issued on weekends are completely automated while all weekday outlooks are modified by the forecaster.
Please refer to the U.S. Prognostic Discussion for an explanation of terms and symbols used on these maps.
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Prognostic Discussions
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Valid: Dec 04 - 08, 2023 (6-10 Day Outlook)
Valid: Dec 06 - 12, 2023 (8-14 Day Outlook)
Issued: Nov 28, 2023 |
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Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EST Tue November 28 2023
6-10 DAY OUTLOOK FOR DEC 04 - 08 2023
The GEFS, Canadian, and ECMWF ensemble means are in good agreement depicting a
deep 500-hPa trough over the northeastern Pacific with enhanced Pacific flow
throughout the western two-thirds of North America. Although the GEFS predicts
a negative Arctic Oscillation (AO) during the next ten days which typically
correlates with below normal temperature across the central contiguous (CONUS),
the enhanced Pacific flow is likely to result in above-normal temperatures for
this region. Strong downsloping surface flow results in above-normal
temperature probabilities exceeding 70 percent across the northern and central
Great Plains. Since yesterday’s day 6 warmth times off and cold air advection
appears stronger today, near to below-normal temperatures are favored for the
eastern CONUS. A two-category change from above to below normal temperatures
was necessary for parts of the Southeast.
The deep trough over the northeastern Pacific and strong onshore flow supports
increased above-normal precipitation probabilities across the Pacific
Northwest, northern California, and northern Intermountain West. The GEFS,
Canadian, and ECMWF ensemble means depict precipitation amounts beginning to
decrease around day 8, December 5. Model solutions remain consistent that a low
pressure system and trailing front progress through the eastern CONUS early
next week which favors near to above normal precipitation along the East Coast.
Due to a blocking ridge over the Davis Strait and Greenland, the deterministic
ECMWF and GFS model runs and many of their ensemble members are slowing the
departure of a low pressure system away from the Northeast. Therefore, this
part of the East Coast has slightly larger probabilities for above-normal
precipitation. Elsewhere, across the central and southwestern CONUS, a mean
500-hPa ridge and the GEFS reforecast tool favors near to below normal
precipitation.
Model solutions feature anomalous 500-hPa troughing over Alaska and a mean
surface low across the Gulf of Alaska. This pattern favors above-normal
precipitation for southeastern Alaska and the reforecast tools also depict
slightly elevated above-normal precipitation probabilities for parts of the
North Slope. The 6-10 day temperature outlook for Alaska was based mostly on
the consolidation tool which favors near to below-normal temperatures for a
majority of the state. The 6-10 day temperature and precipitation outlooks for
Hawaii are also based on the consolidation tool. Above-normal temperatures are
favored for the entire Hawaiian island chain and a slight tilt toward
below-normal precipitation is indicated for the eastern Big Island.
The official 6-10 day 500-hPa height blend consists of 30% of Today's 6z GFS
Ensemble Mean centered on Day 8, 35% of Today's 0z European Ensemble Mean
centered on Day 8, and 35% of Today's 0z Canadian Ensemble Mean centered on Day
8
FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: Above average, 4 out of 5, due to
good agreement among the precipitation tools for the forecast domain along with
high forecast confidence in the temperature outlook for the western and central
CONUS.
8-14 DAY OUTLOOK FOR DEC 06 - 12 2023
The GEFS, ECMWF, and Canadian ensemble means depict a transition to more zonal
and progressive flow during week-2 but maintain positive (negative) 500-hPa
height anomalies across the higher (middle) latitudes of eastern North America.
The reforecast tools continue to feature increased above-normal temperature
probabilities for nearly all of North America due to enhanced Pacific flow
leading into week-2. However, forecast confidence in this warmer outcome is low
along and to the east of the Appalachians. Based on an amplified trough near
the East Coast early in week-2, a predicted negative NAO, and guidance from the
analog tool derived from manual 500-hPa height blend, the week-2 temperature
outlook hedged colder across the eastern CONUS, compared to the automated and
consolidation tools. Near to below-normal temperatures are favored for the
Southeast and Mid-Atlantic.
A 500-hPa trough is forecast to slowly progress inland from the northeastern
Pacific to the interior West which supports elevated above-normal precipitation
probabilities for the Pacific Northwest, northern and central California, Great
Basin, and northern to central Rockies. As the mid-level trough shifts eastward
later in week-2, there is an increasing chance of surface low development
across the north-central CONUS. Therefore, a slight lean towards above-normal
precipitation probabilities is forecast for the increasingly dry climatological
areas of the northern Great Plains and upper Mississippi Valley. Farther to the
south, below-normal precipitation is slightly favored across southern
California, Southwest, and much of the south-central CONUS. Precipitation tools
continue to offer either weak or conflicting signals across the eastern CONUS
where near normal precipitation is favored for most areas. Above-normal
precipitation is slightly favored for Maine due to potential influence from a
low pressure system through day 8 or 9. Above-normal precipitation is also
slightly favored for the Florida Peninsula which is forecast to be at the base
of a 500-hPa trough.
A mid-level trough slightly increases chances of above-normal precipitation
across eastern Alaska, while below-normal precipitation is slightly favored for
the Alaska Peninsula downstream of a mean 500-hPa ridge axis. Northeasterly
surface flow supports elevated below-normal temperature probabilities across
southwestern Alaska, while near to above-normal temperatures are favored for
the remainder of Alaska.
The week-2 temperature outlook for Hawaii is based on the consolidation tool
and favors warmer than normal conditions across the state. Increased
above-normal precipitation probabilities are forecast for much of Hawaii which
may be related to the MJO shifting east from the Indian Ocean to the
west-central Pacific during the next two weeks.
The official 8-14 day 500-hPa height blend consists of: 30% of Today's 6z GFS
Ensemble Mean centered on Day 11, 35% of Today's 0z European Ensemble Mean
centered on Day 11, and 35% 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
continued weak or conflicting signals among the precipitation tools across the
eastern CONUS and a transition to more zonal flow.
FORECASTER: Brad Pugh
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
December 21.
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:
19761130 - 19791109 - 20001205 - 20021206 - 20071122
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:
19791112 - 19931107 - 20001117 - 19761129 - 20071121
6-10 DAY OUTLOOK TABLE
Outlook for Dec 04 - 08 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF A B IDAHO A A NEVADA A B
W MONTANA A A E MONTANA A A WYOMING A A
UTAH A B ARIZONA A B COLORADO A B
NEW MEXICO A B N DAKOTA A N S DAKOTA A N
NEBRASKA A B KANSAS A B OKLAHOMA A B
N TEXAS A B S TEXAS N B W TEXAS A B
MINNESOTA A N IOWA A B MISSOURI A B
ARKANSAS A B LOUISIANA N B WISCONSIN A N
ILLINOIS A B MISSISSIPPI N B MICHIGAN A N
INDIANA A N OHIO A N KENTUCKY A N
TENNESSEE N B ALABAMA N B NEW YORK N A
VERMONT N A NEW HAMP N A MAINE N A
MASS N A CONN N A RHODE IS N A
PENN N A NEW JERSEY N A W VIRGINIA N N
MARYLAND N A DELAWARE N A VIRGINIA N A
N CAROLINA N N S CAROLINA N N GEORGIA N N
FL PNHDL B N FL PENIN B N AK N SLOPE N A
AK ALEUTIAN B N AK WESTERN B N AK INT BSN N N
AK S INT B N AK SO COAST B N AK PNHDL A A
8-14 DAY OUTLOOK TABLE
Outlook for Dec 06 - 12 2023
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A A OREGON A A NRN CALIF A A
SRN CALIF A A IDAHO A A NEVADA A A
W MONTANA A A E MONTANA A A WYOMING A A
UTAH A A ARIZONA A B COLORADO A N
NEW MEXICO A B N DAKOTA A A S DAKOTA A N
NEBRASKA A N KANSAS A B OKLAHOMA A B
N TEXAS A B S TEXAS A N W TEXAS A B
MINNESOTA A A IOWA A N MISSOURI A N
ARKANSAS A B LOUISIANA A N WISCONSIN A N
ILLINOIS A N MISSISSIPPI A N MICHIGAN A N
INDIANA A N OHIO A N KENTUCKY A N
TENNESSEE A N ALABAMA N N NEW YORK A N
VERMONT A N NEW HAMP N N MAINE A N
MASS N N CONN N N RHODE IS N N
PENN A N NEW JERSEY N N W VIRGINIA A N
MARYLAND N N DELAWARE N N VIRGINIA N N
N CAROLINA N N S CAROLINA N N GEORGIA N N
FL PNHDL N N FL PENIN N A AK N SLOPE N A
AK ALEUTIAN B N AK WESTERN B N AK INT BSN N N
AK S INT B N AK SO COAST B N AK PNHDL B N
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.
$$
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Prognostic Discussion,
Surface Forecasts,
500mb Heights and Anomalies,
Time Series of Surface Forecast Skill,
Model Guidance Used
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