Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
037
FXUS06 KWBC 021903
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Thu May 02 2024
6-10 DAY OUTLOOK FOR MAY 08 - 12 2024
The ECENS and GEFS predicted 500-hPa heights continue to be in fairly good
agreement with the Canadian ensemble mean coming into better agreement today.
Negative 500-hPa height anomalies are forecast across Alaska, the western and
northern contiguous U.S. (CONUS), and New England. Near- to above-normal
500-hPa heights are forecast across the southeastern CONUS. The negative
mid-level height anomalies across the West are forecast to progress eastward
across the northern tier during the period. Positive anomalies across the
eastern Pacific may intrude into parts of the Northwest by the end of the 6-10
day period, reducing the mean heights across the Northwest relative to
yesterday.
Mid-level ridging across the southeastern CONUS is forecast to bring
above-normal temperatures to much of the eastern CONUS during the 6-10 day
period. The highest confidence for above-normal temperatures remains across the
Southeast into the Mid-Atlantic ahead of any potential frontal systems
associated with the negative 500-hPa height anomalies forecast to progress
across the CONUS later in the period. There is reduced confidence in
above-normal temperatures in parts of the western Great Lakes where the
mid-level trough is forecast to influence by the end of the period. In the
West, below-normal temperatures are generally favored with the highest
probabilities across parts of the northern Great Basin. In Alaska, below-normal
temperatures are likely across the Alaska Peninsula and southwestern Mainland.
In Southeast Alaska, below-normal temperatures are slightly favored. The
interior Mainland is forecast to see near-normal temperatures. In Hawaii,
below-normal temperatures are favored beneath mid-level troughing.
As the mid-level trough, initially along the West Coast, progresses eastward
above normal precipitation is forecast beneath and just ahead of the trough.
The focus of above-normal precipitation chances has shifted south relative to
yesterday with a broad trough now hanging across the country. Therefore,
above-normal precipitation is now forecast for the Southeast, Tennessee and
Lower-Mississippi Valleys. While the GEFS precipitation reforecast tool remains
weaker relative to the ECENS reforecast the spatial pattern of the anomalies is
consistent, increasing confidence in above-normal across these regions.
However, below-normal precipitation remains favored for Florida and the parts
of the Rio Grande Valley ahead of the mean trough. Along the West Coast,
below-normal precipitation chances are forecast as positive 500-hPa height
anomalies build into the Pacific Northwest. In Alaska, anomalously below-normal
500-hPa heights supports above-normal precipitation across much of the state. A
slight tilt towards above-normal precipitation is favored across much of Hawaii
with negative 500-hPa height anomalies forecast.
The official 6-10 day 500-hPa height blend consists of 10% of Today`s 0z GFS
Ensemble Mean centered on Day 8, 30% of Today`s 6z GFS Ensemble Mean centered
on Day 8, 40% 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 good
agreement among the dynamical model tools but pattern is becoming more
transient reducing confidence.
8-14 DAY OUTLOOK FOR MAY 10 - 16 2024
The dynamical models have weak mean mid-level height anomalies for the week-2
period leading to increased uncertainty across much of the country. The
strongest anomalies are positive across the Pacific Northwest and East Pacific.
Elsewhere, near to below-normal mid-level heights are favored across much of
the CONUS, Alaska, and the central Pacific. The strongest mean 500-hPa height
negative anomalies are found over the Great Lakes and Northeast. Positive
height anomalies are slightly stronger across parts of the Gulf of Mexico and
Southern Plains relative to yesterday.
Above-normal temperatures remain favored across the southeastern CONUS during
the 8-14 day period. The strongest probabilities are forecast closest to the
Gulf Coast and the Florida Peninsula, near the abnormally strong subtropical
ridge. A weakening trough is forecast across the interior Mountain West for
much of the period. This may bring unsettled weather to the region and
generally cooler temperatures. As this trough progresses east it will displace
warmer than normal conditions ahead of it. Therefore, near-normal temperatures
are forecast for the Great Lakes and Northeast. Along the West Coast, a slight
tilt towards above-normal temperatures is favored as ridging is forecast to
begin building into the region during week-2. In Alaska, below-normal
temperatures are favored across much of the state with the strongest chances
forecast across the southern portions. In Hawaii, near-normal temperatures are
forecast with near-normal heights favored over the state.
Below-normal precipitation is favored for the Pacific Northwest and parts of
northern California with ridging building into the region. Generally, unsettled
weather is forecast across the Rockies and into the Plains through to the
eastern seaboard with a broad mid-level trough forecast across the CONUS during
week-2. The strongest chances for above-normal precipitation are forecast for
portions of the southern Mid-Atlantic, Southeast, and Tennessee Valley as a
somewhat stationary front may become established and may help to focus
additional precipitation into these regions. A second area of slightly enhanced
chances for above-normal precipitation is over climatologically quite dry
regions of the interior West where a small amount of precipitation may bring
week-2 totals above-normal. In Florida, near-normal precipitation is favored
during the climatologically driest time of the year. In Alaska, above-normal
precipitation is generally favored across the state with unsettled weather
beneath a mid-level trough continuing. Meanwhile, above-normal precipitation is
again slightly favored for Hawaii consistent with the consolidation of tools.
The official 8-14 day 500-hPa height blend consists of: 5% of Today`s 0z GFS
Ensemble Mean centered on Day 11, 35% of Today`s 6z GFS Ensemble Mean centered
on Day 11, 40% 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: Average, 3 out of 5, Good
agreement in the model tools offset by the progressive pattern leading to
differences in timing among the tools and low mid-level height anomalies.
FORECASTER: Ryan Bolt
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 May
16.
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:
19850423 - 19790412 - 19640503 - 20030516 - 19730419
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:
19640504 - 19850422 - 19790411 - 19990515 - 20030506
6-10 DAY OUTLOOK TABLE
Outlook for May 08 - 12 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B B OREGON B B NRN CALIF B B
SRN CALIF B N IDAHO B N NEVADA B N
W MONTANA B A E MONTANA B A WYOMING B A
UTAH B A ARIZONA B N COLORADO B A
NEW MEXICO B N N DAKOTA B A S DAKOTA B A
NEBRASKA B A KANSAS N N OKLAHOMA A A
N TEXAS A N S TEXAS A B W TEXAS A N
MINNESOTA N A IOWA N A MISSOURI A A
ARKANSAS A A LOUISIANA A A WISCONSIN N A
ILLINOIS A A MISSISSIPPI A A MICHIGAN A A
INDIANA A A OHIO A A KENTUCKY A A
TENNESSEE A A ALABAMA A A NEW YORK A A
VERMONT A A NEW HAMP A A MAINE N 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 N FL PENIN A B AK N SLOPE N A
AK ALEUTIAN B A AK WESTERN B A AK INT BSN N A
AK S INT B A AK SO COAST B A AK PNHDL B A
8-14 DAY OUTLOOK TABLE
Outlook for May 10 - 16 2024
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON A B OREGON A B NRN CALIF A N
SRN CALIF B A IDAHO N N NEVADA N A
W MONTANA N N E MONTANA N N WYOMING B A
UTAH B A ARIZONA B N COLORADO B A
NEW MEXICO B A N DAKOTA N N S DAKOTA B N
NEBRASKA B A KANSAS B A OKLAHOMA N A
N TEXAS A A S TEXAS A A W TEXAS N A
MINNESOTA N N IOWA B N MISSOURI N A
ARKANSAS A A LOUISIANA A A WISCONSIN N N
ILLINOIS N N MISSISSIPPI A A MICHIGAN N N
INDIANA N N OHIO N A KENTUCKY N A
TENNESSEE A A ALABAMA A A 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 A
MARYLAND N A DELAWARE N 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 N A
AK S INT B A AK SO COAST B A AK PNHDL B 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.
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