720
FXUS06 KWBC 031903
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 03 2024

6-10 DAY OUTLOOK FOR MAY 09 - 13 2024

The ECENS, GEFS, and Canadian ensemble mean predicted 500-hPa heights are in
good agreement with each other for much more robust mid-level trough to develop
across the eastern contiguous U.S. (CONUS) today. This is a pattern change that
some of the ensemble members have been predicting for the past several model
cycles but there is more agreement in the model tools today for a pattern shift
across the CONUS. The consolidation of the negative anomalies over the eastern
CONUS results in several changes in the temperature and precipitation forecasts
across the CONUS. Over the West, mid-level ridging looks likely to dominate
much of the Pacific Northwest during the period. Some near-normal heights
remain forecast for the southwestern CONUS. Weakly below-normal 500-hPa heights
are forecast for Alaska. Near-normal heights are forecast for Hawaii.

During the 6-10 day period, a cold front is forecast to be progressing across
the eastern CONUS. This will introduce much colder temperatures to regions that
in prior forecasts were forecast to see above-normal temperatures. Therefore,
the above-normal temperature chances are confined to the immediate Gulf of
Mexico Coast and the Atlantic states. Behind this frontal system colder
temperatures are likely to prevail and below-normal is favored for much of the
central CONUS. While along the West Coast, beneath the strongly positive
500-hPa height anomalies forecast today, above-normal temperatures are favored
with the strongest probabilities in the Pacific Northwest. Reforecast, raw, and
analog tools run on the manual 500-hPa height blend all support this forecast
across the CONUS despite there being large changes from yesterday. In Alaska,
continued weakly below-normal 500-hPa height anomalies leads to continued
chances for below-normal temperatures across the state. In Hawaii, near- to
below-normal temperatures are forecast consistent with the consolidation of
tools.

The 6-10 day precipitation forecast also sees fairly large changes relative to
prior forecasts with generally low confidence across most of the country. In
the Pacific Northwest, below-normal precipitation is likely with chances
exceeding 50% beneath the strong positive 500-hPa height anomalies. The
below-normal chances overspread the northern Rockies and into the Central
Plains and Middle Mississippi Valley as the eastern trough strengthens. Along
the southern and eastern edge of the trough above-normal precipitation is
slightly favored as a surface frontal boundary is likely to become established
that may help to focus precipitation along the East Coast and Gulf Coast. Areas
of surface low-pressure may develop in the southern Rockies that may bring
precipitation to the region. In Alaska, above-normal precipitation is forecast
along the Gulf of Alaska Coast and the eastern interior as weak troughing may
bring weak onshore flow. In Hawaii, near to above-normal precipitation is
favored.

The official 6-10 day 500-hPa height blend consists of 20% of Today`s 0z GFS
Ensemble Mean centered on Day 8, 20% 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: Below-Average, 2 out of 5, Good
agreement in some of the model tools offset by a progressive pattern with major
changes relative to yesterday.

8-14 DAY OUTLOOK FOR MAY 11 - 17 2024

The dynamical models continue to have weak mean mid-level height anomalies for
the week-2 period leading to increased uncertainty across much of the country.
However, the tools generally agree on a mid-level ridge across the western
CONUS with a mid-level trough across the East. This is a more amplified signal
than in prior forecasts leading to changes for the temperature and
precipitation forecasts for the CONUS. In Alaska, weak troughing continues to
be forecast with above-normal 500-hPa heights over the Aleutians and
near-normal anomalies across the Mainland. In Hawaii, near-normal heights are
forecast.

Below-normal temperatures chances are stronger and more pervasive across the
eastern CONUS today relative to yesterday with a more amplified trough
developing over the East. This leads to below-normal temperature favored for
most of the eastern CONUS excluding parts of the Florida peninsula which is
likely to remain south of the a frontal feature. Along the immediate Gulf
Coast, near-normal temperatures are favored as a frontal boundary pushes
through the region early in week-2. Across the West, above-normal temperatures
are favored beneath a strong mid-level ridge. While in Alaska, below-normal
temperatures are slightly favored with continued weak troughing impacting the
state. Hawaii is forecasted to see below-normal temperatures.

Below-normal precipitation is favored for the Pacific Northwest and parts of
northern California with ridging over the region. Below-normal precipitation
chances extend eastward through the northern Rockies into the Plains, and the
Mississippi, Ohio and Tennessee Valleys. These eastern regions are likely to be
beneath an amplified mid-level trough that will focus precipitation south and
east into parts of the Northeast, Florida, and Southern Plains where
above-normal precipitation is slightly favored. In parts of the southern
Rockies and Great Basin, some energy may undercut the mid-level ridge over the
Northwest that may bring chances for precipitation in climatologically fairly
dry regions. Any precipitation in these areas may bring 7 day totals above the
67th climatological percentile. In Alaska, above-normal precipitation is
generally favored across the state with unsettled weather beneath a mid-level
trough continuing. Meanwhile, near to above-normal precipitation is slightly
favored for Hawaii consistent with the consolidation of tools.

The official 8-14 day 500-hPa height blend consists of: 10% of Today`s 0z GFS
Ensemble Mean centered on Day 11, 30% 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: Below-Average, 2 out of 5, Good
agreement in the model tools offset by a progressive pattern with major changes
relative to yesterday.

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 - 19790413 - 19750429 - 20030517 - 19640503


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:
19750429 - 19640503 - 19790412 - 19980516 - 19850422


6-10 DAY OUTLOOK TABLE
Outlook for May 09 - 13 2024

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



8-14 DAY OUTLOOK TABLE
Outlook for May 11 - 17 2024

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    N     NEVADA      A    N
W MONTANA   A    B     E MONTANA   A    B     WYOMING     N    N
UTAH        A    A     ARIZONA     N    N     COLORADO    N    A
NEW MEXICO  B    A     N DAKOTA    N    B     S DAKOTA    B    B
NEBRASKA    B    N     KANSAS      B    N     OKLAHOMA    B    N
N TEXAS     B    A     S TEXAS     N    A     W TEXAS     B    A
MINNESOTA   B    B     IOWA        B    N     MISSOURI    B    N
ARKANSAS    B    N     LOUISIANA   B    N     WISCONSIN   B    B
ILLINOIS    B    B     MISSISSIPPI B    N     MICHIGAN    B    B
INDIANA     B    N     OHIO        B    B     KENTUCKY    B    N
TENNESSEE   B    N     ALABAMA     B    N     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    N     NEW JERSEY  B    A     W VIRGINIA  B    N
MARYLAND    B    N     DELAWARE    B    N     VIRGINIA    B    N
N CAROLINA  B    N     S CAROLINA  B    N     GEORGIA     B    N
FL PNHDL    N    N     FL PENIN    A    A     AK N SLOPE  B    N
AK ALEUTIAN B    N     AK WESTERN  B    N     AK INT BSN  B    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.

$$