558
FXUS06 KWBC 221903
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Wed May 22 2024

6-10 DAY OUTLOOK FOR MAY 28 - JUN 01, 2024

Dynamical models are in good agreement regarding the 500-hPa height pattern
across North America during the 6-10 day period. A potent trough is forecast to
move across the Northeast early in the period, with anomalous ridging predicted
upstream over the western and central CONUS. Troughing is forecast to shift
from southeastern Alaska toward the northwestern CONUS, but models depict this
feature weakening with time, with additional troughing forecast to develop
across the Bering Sea and southwestern Alaska by the end of the period. Todays
manual 500-hPa height blend depicts near- to below-normal heights for most of
the eastern CONUS, excluding parts of Florida and Maine where slightly
above-normal heights are predicted farther displaced from the trough.
Above-normal heights are favored for much of the western half of the CONUS,
along with Mainland Alaska. Near- to slightly below-normal heights are
indicated over the Aleutians and Southeast Alaska due to greater influence from
troughing. Near- to below-normal heights are forecast across the Hawaiian
Islands, with troughing in the vicinity of the state forecast to gradually
weaken.

Troughing favors increased probabilities of near- to below-normal temperatures
across much of the eastern U.S. Enhanced probabilities for above-normal
temperatures are favored across northern New England and closer to the Gulf
Coast and Southeast, underneath weaker height anomalies and consistent with the
GEFS and ECMWF reforecast tools. Increased chances for above-normal
temperatures are favored over much of the West due to predicted ridging, with
below-normal temperatures favored across parts of the Pacific Northwest due to
the influence from potential troughing upstream. Above-normal temperature
chances are increased over parts of northern and central Mainland Alaska, while
below-normal temperature probabilities are increased over southern Alaska,
including parts of the Aleutians and Southeast Alaska. Near-normal temperatures
are forecast over most of Hawaii, with above-normal temperatures slightly
favored across the Big Island given the predicted weakening of the trough.

Above-normal precipitation probabilities are increased over the northeastern
CONUS due to the lingering impacts from a surface low forecast early in the
period. Enhanced northwesterly mid-level flow and surface high pressure on the
backside of the departing tough in the East favor enhanced chances for
below-normal precipitation across parts of the east-central CONUS, extending to
the central Gulf Coast. Southerly return flow around the surface high favors
enhanced chances of above-normal precipitation across portions of the Central
and Southern Plains, supported by the ECMWF and GEFS reforecast tools.
Below-normal precipitation probabilities are elevated over much of the western
CONUS underneath ridging, except for portions of the Pacific Northwest where
above-normal precipitation chances are increased due to a potential trough
approaching the West Coast. Above-normal precipitation chances are elevated
over most of Alaska due to the trend toward more troughing over the Bering Sea
late in the period and supported by most of the dynamical precipitation
forecast tools. In Hawaii, near- to above-normal precipitation probabilities
are increased ahead of weakening troughing.

The official 6-10 day 500-hPa height blend consists of 30% of Today`s 0z GFS
Ensemble Mean centered on Day 8, 5% of Today`s operational 0z GFS centered on
Day 8, 30% of Today`s 0z European Ensemble Mean centered on Day 8, 5% 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: Above average, 4 out of 5, due to
good agreement among the forecast tools, offset by decreasing amplification
toward the end of the period.

8-14 DAY OUTLOOK FOR MAY 30 - JUN 05, 2024

Early in week-2, the troughing predicted across the East is forecast to
gradually weaken and lift out, with the overall mid-level flow pattern across
the CONUS becoming more zonal. While periodic episodes of ridging and troughing
are possible as depicted in the 0z GEFS, ECMWF, and Canadian ensembles, it is
difficult to pinpoint the exact placement and timing of these shortwave
features, although the dynamical models generally depict a broad area of
increasing heights across the CONUS by the end of the period. Troughing is
forecast to build across the Bering Sea and southwestern Alaska, with weak
ridging upstream over eastern and Southeast Alaska. The week-2 manual 500-hPa
height blend depicts near-normal heights over parts of the Eastern Seaboard and
slightly above-normal 500-hPa heights across much of the central and western
CONUS along with northern New England. Below-normal heights are predicted
across the Aleutians and southwestern Mainland Alaska, with near-normal heights
forecast over the rest of the state. Near- to above-normal heights are forecast
over Hawaii.

Probabilities for below-normal temperatures are slightly elevated across
portions of the Ohio and Tennessee Valleys, Mid-Atlantic, and Northeast, with
the coolest conditions likely early in week-2, with temperatures moderating
toward the middle of the period as the troughing weakens. Above-normal
temperature chances remain increased over the Gulf Coast, Florida, and northern
New England, further displaced from this troughing and underneath weaker
mid-level height anomalies. Increased Pacific flow along with some ridging
favors increased chances for above-normal temperatures across much of the West,
Great Plains, and Upper Mississippi Valley. Below-normal temperature chances
are increased over southern portions of Alaska, with above-normal temperature
chances enhanced over the northern and central Mainland. Near- to above-normal
temperatures are forecast across Hawaii, consistent with the consolidated
forecast tool.

Enhanced chances for above-normal precipitation are favored across Upstate New
York and New England as troughing and associated surface low pressure linger
across the region early in the period. As this trough weakens, the mid-level
flow pattern across the East is favored to become more zonal leading to a large
area of near-normal precipitation highlighted over much of the eastern CONUS.
Slightly enhanced chances of below-normal precipitation are forecast across
parts of the Gulf Coast and Southeast underneath surface high pressure, with
southerly return flow favoring enhanced above-normal precipitation chances
across parts of the Great Plains and Mississippi Valley. Weakly positive
mid-level height anomalies favor a slight tilt toward elevated below-normal
precipitation probabilities across the Interior West, with increasing onshore
flow leading to slightly above-normal precipitation chances along the West
Coast. Troughing favored across southwestern Alaska favors enhanced chances for
above-normal precipitation across most of the state. Near- to below-normal
precipitation is predicted across Hawaii.

The official 8-14 day 500-hPa height blend consists of: 40% of Today`s 0z 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, due to
continued good agreement among the forecast tools, offset by decreasing
predictability as the mid-level pattern becomes more zonal.

FORECASTER: Thomas Collow

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:
19990531 - 19620602 - 20030506 - 19990605 - 19890518


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:
19990603 - 20030506 - 19890517 - 19640505 - 19620602


6-10 DAY OUTLOOK TABLE
Outlook for May 28 - Jun 01, 2024

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



8-14 DAY OUTLOOK TABLE
Outlook for May 30 - Jun 05, 2024

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

$$