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FXUS06 KWBC 171903
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Fri May 17 2024
6-10 DAY OUTLOOK FOR MAY 23 - 27 2024
Today's model solutions are in good agreement on the predicted amplified
500-hPa circulation pattern across North America and surrounding regions during
the 6-10 day period. The manual 500-hPa height blend is based primarily on the
ensemble means from the GEFS, ECMWF, and Canadian models due to recent model
skill. The resultant manual blend features negative 500-hPa height anomalies
over much of the western and north-central contiguous U.S. (CONUS). Positive
height anomalies are forecast over the southern tier of the CONUS. These
positive height anomalies are associated with a subtropical ridge. Over the
Alaska domain, a weak trough is depicted over the Bering Sea and western
Mainland, while mid-level ridging is forecast over the Aleutians.This mid-level
ridging represents the northeastern extent of a broad, zonally elongated
anomalous ridge that is predicted over much of the North Pacific. A weak
mid-level trough is anticipated over the Hawaiian Islands.
Negative 500-hPa height anomalies and mid-level troughing over the western
CONUS favor below-normal temperatures over the western and north-central CONUS
eastward into the Great Lakes region. Enhanced chances for above-normal
temperatures are predicted over much of the south-central and eastern CONUS due
to subtropical ridging and above-normal 500-hPa height anomalies, supported by
most of the dynamical temperature forecast tools. Probabilities favoring above
normal temperatures exceed 80% for portions of South Texas. In Alaska,
below-normal temperature chances are increased over much of the central and
western Mainland Alaska and the adjacent Alaska Peninsula associated with the
forecast of a weak trough in that region, while above-normal temperatures are
favored in portions of the North Slope, consistent with most temperature
guidance. For the Panhandle, most of the raw and bias-corrected temperatures
support below normal temperatures, whereas the various reforecast temperature
fields favor above normal temperatures. In Hawaii, below-normal temperature
probabilities are favored across Hawaii underneath weak troughing and negative
height anomalies.
The subtropical ridge favors below normal precipitation for eastern Arizona,
New Mexico, southern Colorado, western and far southern parts of Texas, and
southern Florida. In contrast, near- to above-normal precipitation
probabilities are increased over the remainder of the CONUS due to southerly
return flow associated with mean surface high pressure over the Southeast and
the mid-level trough expected to linger in the region through much of the
period, and supported by most of the dynamical precipitation forecast tools.
Above normal precipitation chances are elevated over most of Alaska in advance
of a mid-level trough and widespread onshore flow. The exception is over the
southern Panhandle, where near-normal precipitation is favored under a
mid-level ridge and positive height anomalies. In Hawaii, anomalously wet
conditions statewide are likely in advance of a 500-hPa trough.
The official 6-10 day 500-hPa height blend consists of 40% of Today's GFS
Superensemble Mean centered on Day 8, 30% of Today's 0z European Ensemble Mean
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: Above average, 4 out of 5, due to
good agreement among model solutions and forecast temperature and precipitation
tools.
8-14 DAY OUTLOOK FOR MAY 25 - 31 2024
Ensemble mean solutions for the 8-14 day period predict a fairly consistent
500-hPa circulation pattern relative to the 6-10 day period across North
America and the surrounding regions. During week-2, positive 500-hPa height
anomalies persist over the North Pacific and over much of the southern tier of
the CONUS and Maine. Troughs are predicted along the West Coast and over the
Great Lakes region. For Alaska, weak anomalous troughing is indicated over the
Bering Sea and the western coast, with mid-level ridging and positive height
anomalies dominating the remainder of the state. In Hawaii, a weak trough with
below-normal 500-hPa heights continue to be forecast northwest of Hawaii.
Above normal temperatures are favored for the south-central and southeastern
CONUS as well as Maine due to subtropical ridging and above-normal 500-hPa
heights predicted around the region, and aligns well with the overall synoptic
pattern. A low-amplitude trough near the West Coast and the Great Lakes tilt
the odds towards below normal temperatures for the West Coast, parts of the
Northern and Central Plains, the Upper and Middle Mississippi Valley, and Upper
Great Lakes region. In Alaska, below normal temperature chances are increased
over much of the central and southern portions of the state, with above normal
temperature chances enhanced over the North Slope. In Hawaii, below-normal
temperatures are likely over the State due to the below-normal 500-hPa heights.
Enhanced chances for above-normal precipitation are favored over northern
California and the Pacific Northwest in association with a weak trough
predicted over the West Coast. Above-normal precipitation is also forecast over
much of the central and eastern CONUS, consistent with the consolidation and
auto precipitation tools. Below normal precipitation is favored across parts of
Arizona, New Mexico, and far southwestern Texas, also supported by the
Consolidation and auto precipitation tools. For Hawaii and Alaska,
predominantly wet conditions are favored relative to normal with the same
general synoptic features in place as was the case with the 6-10 day outlook.
The official 8-14 day 500-hPa height blend consists of: 35% of Today's 6z GFS
Ensemble Mean centered on Day 11, 45% of Today's 0z European Ensemble Mean
centered on Day 11, and 20% 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
good run-to-run continuity among forecast models, offset by differences between
models regarding strength and position of various synoptic features.
FORECASTER: Luke 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
June 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:
19660519 - 19990529 - 19920509 - 19890516 - 19990430
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:
19660518 - 19990528 - 19920509 - 19620529 - 19640426
6-10 DAY OUTLOOK TABLE
Outlook for May 23 - 27 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON B A NRN CALIF B A
SRN CALIF B N IDAHO B A NEVADA B A
W MONTANA B A E MONTANA B A WYOMING B A
UTAH B A ARIZONA B N COLORADO B N
NEW MEXICO A B N DAKOTA B A S DAKOTA B A
NEBRASKA B A KANSAS N A OKLAHOMA A A
N TEXAS A A S TEXAS A N W TEXAS A B
MINNESOTA B A IOWA B A MISSOURI N A
ARKANSAS A A LOUISIANA A A WISCONSIN B A
ILLINOIS N A MISSISSIPPI A A MICHIGAN N A
INDIANA N A OHIO N A KENTUCKY A A
TENNESSEE A A ALABAMA A A NEW YORK A A
VERMONT A A NEW HAMP A A MAINE A A
MASS A A CONN A A RHODE IS A A
PENN A A NEW JERSEY A A W VIRGINIA A A
MARYLAND A A DELAWARE A A VIRGINIA A A
N CAROLINA A A S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN A N AK N SLOPE N A
AK ALEUTIAN B A AK WESTERN B A AK INT BSN B A
AK S INT B A AK SO COAST B A AK PNHDL N N
8-14 DAY OUTLOOK TABLE
Outlook for May 25 - 31 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B A OREGON B A NRN CALIF B A
SRN CALIF B N IDAHO N N NEVADA N N
W MONTANA N N E MONTANA N N WYOMING N N
UTAH N N ARIZONA N N COLORADO N A
NEW MEXICO N N N DAKOTA B A S DAKOTA B A
NEBRASKA B A KANSAS N A OKLAHOMA A A
N TEXAS A A S TEXAS A N W TEXAS A A
MINNESOTA B A IOWA B A MISSOURI N A
ARKANSAS A A LOUISIANA A N WISCONSIN B A
ILLINOIS N A MISSISSIPPI A A MICHIGAN N A
INDIANA N A OHIO N A KENTUCKY N A
TENNESSEE N A ALABAMA A A NEW YORK N A
VERMONT N A NEW HAMP N A MAINE A A
MASS N A CONN N A RHODE IS N A
PENN N A NEW JERSEY N A W VIRGINIA N A
MARYLAND N A DELAWARE N A VIRGINIA N A
N CAROLINA A A S CAROLINA A A GEORGIA A A
FL PNHDL A A FL PENIN A A AK N SLOPE A A
AK ALEUTIAN B A AK WESTERN B A AK INT BSN B A
AK S INT B A AK SO COAST B A AK PNHDL N 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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