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FXUS06 KWBC 241928
PMDMRD
Prognostic Discussion for 6 to 10 and 8 to 14 day outlooks
NWS Climate Prediction Center College Park, MD
300 PM EDT Wed April 24 2019
6-10 DAY OUTLOOK FOR APR 30 - MAY 04, 2019
Today's ensemble mean solutions are in good agreement on the 500-hPa height
anomalies forecast across most of the CONUS. A very amplified ridge is expected
over the Alaska region. Downstream an amplified trough is forecast over Western
Canada and parts of the Western CONUS. Above normal ridging is predicted over
the Eastern CONUS. Models have generally been trending toward larger positive
height anomalies in the east each day, and have been in good agreement in
recent days, so confidence is high that this amplified pattern will develop
during the 6-10 day period.
The highly anomalous ridging predicted over Alaska favors above normal
temperatures over western and central portions of the state. Relatively cold
low-level flow from Canada favors below normal temperatures over parts of far
eastern Alaska. Below normal temperatures are favored for parts of the
Northwestern CONUS due to forecast below normal heights, associated with a
mid-level trough. Below normal temperatures are favored eastward as well,
across the Northern and Central Plains, much of the Great Lakes Region, and
parts of New England, due to the forecast passage of several cold fronts. Aside
from this, residual warmth is anticipated across much of California, southern
Nevada, Arizona, and New Mexico, with the approach of a mid-level trough. The
predicted 500-hPa ridge and associated positive height anomalies favor above
normal temperatures across the Southern Plains, and from the Lower and Middle
Mississippi Valley eastward to the Atlantic Coast, from New Jersey to Florida.
Probabilities for above normal temperatures exceed 70% over much of the
Southeast.
The strong ridge predicted over Alaska is predicted to lift the storm track
poleward, favoring below normal precipitation for much of southern and central
Alaska (including the Panhandle) and confining the favored areas of above
normal precipitation to the Bering Sea coast and the North Slope. Below normal
precipitation is favored over extreme western parts of the CONUS, west of a
nearby trough. Near and east of this trough, odds favor above normal
precipitation for much of the remainder of the region west of the Continental
Divide. Near and east of the Divide, moisture from the Gulf of Mexico
interacting with several cold fronts increases the likelihood of above normal
precipitation for the Great Plains, Mississippi Valley, Great Lakes region,
Ohio and Tennessee Valleys, mid-Atlantic, and much of the Northeast. Much of
the southeastern portion of the CONUS is predicted to have near normal
precipitation, which represents a compromise between wetter tools and a drier
synoptic pattern that would be favored given the predicted ridging over this
region.
The official 6-10 day 500-hPa height blend consists of 25% of Today's 0z GFS
Ensemble Mean centered on Day 8, 25% of Today's 6z GFS Ensemble Mean centered
on Day 8, 30% 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: Above average, 4 out of 5, due to
good agreement between available models and tools.
8-14 DAY OUTLOOK FOR MAY 02 - 08 2019
By the week-2 period, the 500-hPa height pattern is forecast to deamplify. The
resulting temperature and precipitation probability forecasts for the week-2
period, however, are quite similar to the 6-10 day period, though probabilities
are somewhat lower due to the forecast pattern deamplifying. For the
temperature pattern, the outlook favors near normal temperatures over a large
portion of the western CONUS, associated with discrepancies in various tools.
For week-2 precipitation, there is better agreement among the surface tools
(relative to the 6-10 day period) for surface high pressure to slide off the
Southeast coast, increasing the odds for above normal precipitation across the
Southeast, particularly Florida, which is more distant from the center of the
500-hPa ridge over the Eastern CONUS.
The official 8-14 day 500-hPa height blend consists of: 25% of Today's 0z GFS
Ensemble Mean centered on Day 11, 25% of Today's 6z GFS Ensemble Mean centered
on Day 11, 30% 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: Near average, 3 out of 5, due to
good agreement between available models and tools, offset by significant
uncertainty in the predicted temperature pattern over the western CONUS.
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 1981-2010 base period means for
temperature...precipitation...and 500-hpa heights 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:
19640412 - 19540410 - 19700503 - 20020412 - 19850413
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:
19700502 - 19540413 - 19640411 - 20020412 - 19870420
6-10 DAY OUTLOOK TABLE
Outlook for Apr 30 - May 04, 2019
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON B B OREGON N B NRN CALIF A B
SRN CALIF A A IDAHO B A NEVADA N A
W MONTANA B N E MONTANA B A WYOMING B A
UTAH N A ARIZONA A A COLORADO B A
NEW MEXICO A A N DAKOTA B A S DAKOTA B A
NEBRASKA B A KANSAS B A OKLAHOMA N A
N TEXAS A A S TEXAS A A W TEXAS N A
MINNESOTA B A IOWA B A MISSOURI N A
ARKANSAS A A LOUISIANA A N WISCONSIN B A
ILLINOIS N A MISSISSIPPI A N MICHIGAN B A
INDIANA A A OHIO A A KENTUCKY A A
TENNESSEE A A ALABAMA A N NEW YORK N A
VERMONT B A NEW HAMP B A MAINE B N
MASS B A CONN N A RHODE IS N A
PENN A A NEW JERSEY A A W VIRGINIA A A
MARYLAND A A DELAWARE A N VIRGINIA A N
N CAROLINA A N S CAROLINA A N GEORGIA A N
FL PNHDL A N FL PENIN A N AK N SLOPE A A
AK ALEUTIAN A A AK WESTERN A A AK INT BSN N B
AK S INT A B AK SO COAST A B AK PNHDL N B
8-14 DAY OUTLOOK TABLE
Outlook for May 02 - 08 2019
STATE TEMP PCPN STATE TEMP PCPN STATE TEMP PCPN
WASHINGTON N B OREGON N N NRN CALIF N A
SRN CALIF N A IDAHO B A NEVADA N A
W MONTANA B N E MONTANA B A WYOMING B A
UTAH N A ARIZONA N A COLORADO N A
NEW MEXICO A A N DAKOTA B A S DAKOTA B A
NEBRASKA N A KANSAS A A OKLAHOMA A A
N TEXAS A A S TEXAS A A W TEXAS A A
MINNESOTA B A IOWA N A MISSOURI A A
ARKANSAS A A LOUISIANA A A WISCONSIN B A
ILLINOIS A A MISSISSIPPI A A MICHIGAN N A
INDIANA A A OHIO A A KENTUCKY A A
TENNESSEE A A ALABAMA A A NEW YORK N A
VERMONT N A NEW HAMP N A MAINE B N
MASS N 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 A AK N SLOPE N A
AK ALEUTIAN A A AK WESTERN A N AK INT BSN N N
AK S INT N B AK SO COAST N B AK PNHDL N B
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.
$$