326
FXUS06 KWBC 071902
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Tue May 07 2024

6-10 DAY OUTLOOK FOR MAY 13 - 17 2024

Today`s dynamical model solutions are in fairly good agreement on the predicted
500-hPa circulation pattern across North America and surrounding regions during
the 6-10 day period. The manual 500-hPa height blend is based on nearly-equal
weighting of the 0z GFS, ECMWF, and Canadian ensemble means due to comparable
model skill over the past two months. The resultant manual blend features
moderate-to-strong anomalous ridges over the western Pacific, the eastern
Pacific, and the central Atlantic. A moderately amplified mid-level trough and
below-normal heights are predicted over Alaska, with the mean trough axis near
the west coast of Alaska. The anomalous ridge anticipated over the eastern
Pacific extends eastward across much of the western contiguous U.S. (CONUS),
with a channel of slightly above-normal heights continuing eastward across the
north-central states, Great Lakes region, Northeast, and Mid-Atlantic states.
East of the Rocky Mountains, one trough is forecast over the eastern Great
Lakes and Northeast, while another trough is forecast to extend from the Upper
Mississippi Valley southwestward to the southern High Plains and southern
Rockies. Weak troughing with near-normal 500-hPa heights is favored for Hawaii.

Mid-level ridging and positive 500-hPa height anomalies across the western
CONUS, combined with the aforementioned channel/extension of slightly
above-normal 500-hPa heights across the Northern CONUS, favors above-normal
temperatures for a large portion of the CONUS. The highest probabilities
favoring above-normal temperatures exceed 70% over northern California,
northwestern Nevada, and southeastern Oregon. Above-normal temperatures are
also favored over southern Texas and Florida, with remaining portions of the
southern CONUS depicted as near-normal. In Alaska, mid-level troughing and
below-normal 500-hPa heights favor below-normal temperatures across the state.
In Hawaii, near- to above-normal temperatures are forecast, consistent with the
consolidation of tools.

Below-normal precipitation is favored from Washington southward to northern
California, and eastward to central Montana. This is associated with anomalous
ridging and positive 500-hPa height anomalies across this region. Across most
of the remainder of the CONUS, however, above-normal precipitation is favored.
For approximately the northeast quarter of the CONUS, odds favoring
above-normal precipitation are slightly elevated, due to shortwave energy
moving through the region. Higher probabilities for above-normal precipitation
are depicted across the southern CONUS. This is associated with surface high
pressure off the East Coast leading to increased onshore flow across the Gulf
Coast states, a nearby warm front, and the mid-level trough noted earlier over
the Plains. The expected precipitation may be enhanced by the development of
surface low pressure over the southern High Plains. Probabilities favoring
wetter-than-normal conditions surpass 60% for east-central portions of the Gulf
Coast region. Weak residual troughing across the Southwest elevates the
probability of above-normal precipitation for much of that region, supported by
GEFS and ECMWF ensemble mean reforecast precipitation guidance. In Alaska,
above-normal precipitation is forecast over much of Alaska associated with
broad onshore flow and mid-level troughing. In Hawaii, above-normal
precipitation is favored due to the proximity of a weak 500-hPa trough.

The official 6-10 day 500-hPa height blend consists of 33% of Today`s 0z GFS
Ensemble Mean centered on Day 8, 34% of Today`s 0z European Ensemble Mean
centered on Day 8, and 33% 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 15 - 21 2024

The two anomalous ridges predicted over the western and eastern Pacific during
the earlier 6-10 day period are forecast to consolidate into one broad
anomalous ridge that extends northward into southwestern Alaska, accompanied by
above-normal 500-hPa heights. The trough anticipated over Alaska during the
6-10 day period is expected to shift westward in week-2, with below-normal
500-hPa heights remaining only over the northwestern portion of the state. A
weak trough-ridge-trough pattern is indicated over the CONUS with heights
slightly above-normal across the West, and near-normal across the Central and
Eastern states. A weak trough with near-normal 500-hPa heights continued to be
predicted in the vicinity of Hawaii.

Above-normal temperatures are favored over nearly all of the CONUS, consistent
with todays reforecast temperatures from the GEFS and ECMWF ensemble means.
Odds favoring above-normal temperatures are weak across the East due to
conflicting signals between significantly warmer reforecast temperatures and
cooler raw temperature guidance from these ensemble means. In Alaska,
below-normal temperatures continue to be favored by most tools, even though the
trough impacting the state is expected to weaken during week-2. In Hawaii,
near-normal temperatures are favored, representing a compromise between the ERF
consolidation tool, the auto temperature forecast, and near-normal 500-hPa
heights.

Below-normal precipitation is favored from the Pacific Northwest and
northwestern California to western Montana, due to mid-level ridging
anticipated over the region. Near- to above-normal precipitation is forecast
over the remainder of the CONUS due to southerly return flow associated with
mean surface high pressure over the Southeast and a broad mid-level trough
expected to progress across the East. This is supported by most precipitation
guidance. In Alaska, above-normal precipitation is generally favored across the
state with unsettled weather beneath a mid-level trough continuing. Meanwhile,
near- to mostly above-normal precipitation is slightly favored for Hawaii
consistent with the consolidation of tools and auto-precipitation forecast.

The official 8-14 day 500-hPa height blend consists of: 35% of Today`s 0z GFS
Ensemble Mean centered on Day 11, 35% of Today`s 0z European Ensemble Mean
centered on Day 11, and 30% of Today`s 0z Canadian Ensemble Mean centered on
Day 11


FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: Near average, 3 out of 5, with
good agreement in the overall circulation pattern for the period, offset by
weaker signals and some disagreement among precipitation and temperature tools.

FORECASTER: Anthony A

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:
19750426 - 19980513 - 19750502 - 19640501 - 19550422


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:
19750426 - 19550422 - 19980512 - 19980517 - 19640429


6-10 DAY OUTLOOK TABLE
Outlook for May 13 - 17 2024

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



8-14 DAY OUTLOOK TABLE
Outlook for May 15 - 21 2024

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

$$