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000
FXUS06 KWBC 191924
PMDMRD
PROGNOSTIC DISCUSSIONS FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM UTC FRI APR 19 2024

A transient 500-hPa height pattern is forecast across North America during the
6-10 day period. At the outset of the period, troughing and negative height
anomalies are predicted across eastern Canada and extending into the Great
Lakes and Northeast. Amplified ridging is forecast to shift eastward across the
CONUS with troughing developing near the West Coast in its wake. The pattern
across Alaska is predicted to quickly transition from enhanced ridging and
positive height anomalies at the outset of the period to more influence from
troughing over the Bering Sea and Arctic. Near- to above-normal heights are
predicted across Hawaii due to increased ridging over the central Pacific.

Models are in good agreement regarding near- to below-normal temperatures
across much of  the western CONUS during the period, consistent with decreasing
mid-level heights and increasing troughing in the region. Today’s forecast
depicts enhanced probabilities for below-normal temperatures over much of the
Northeast and Mid-Atlantic for the period as a whole, along with increased
chances for above-normal temperatures across the interior western and central
CONUS, and Southeast. Ridging and above-normal 500-hPa heights across Mainland
Alaska and Southeast Alaska favor increased chances for above-normal
temperatures across southern Mainland Alaska and Southeast Alaska. Elevated
probabilities for below-normal temperatures are forecast for the western
Aleutians and the northern state, and supported by GEFS temperature reforecast
tool. Near-normal temperatures are predicted across the Hawaiian Islands.

Return flow around surface high pressure favors increasing precipitation
chances across parts of the central and eastern CONUS, except for the eastern
seaboard where near- to below-normal precipitation is indicated. Above-normal
precipitation probabilities are increased over much of the West due to
troughing forecast to develop near the West Coast. Increased southerly flow
across Alaska ahead of a developing troughing over the Bering Sea favors
enhanced chances for near- to above-normal precipitation across the state.
Near- to below-normal precipitation chances are elevated across Hawaii due to
increasing ridging over the central Pacific.

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: 3 out of 5, Average, due to
general agreement in the models regarding the mid-level pattern evolution,
offset by lack of forecast tools due to IT outage.

The 500-hPa height pattern during week-2 is forecast to continue to depict
amplified ridging and positive 500-hPa height anomalies continuing to expand
across the eastern CONUS. Troughs are predicted across the western CONUS and
the Aleutians, while ridging and above-normal 500-hPa heights are forecast over
Mainland Alaska and Southeast Alaska. Ridging and above-normal 500-hPa heights
are forecast over Hawaii.

The prevailing mid-level height pattern across the CONUS favors an anomalously
warm pattern across much of the CONUS east of the Rockies during week-2. The
highest probabilities for above-normal temperatures (greater than 70 percent)
are across parts of the south-central CONUS. Near- to below-normal temperatures
are favored along the West Coast, Great Basin, and Southwest due to more
troughing. Decreasing mid-level heights favor elevated probabilities for
below-normal temperatures across portions of northern Mainland Alaska and the
Aleutians, with above-normal temperature remaining favored downstream across
the southeastern Mainland and Southeast Alaska. Increased chances for
near-normal temperatures remain forecast across Hawaii.

The trend toward relatively lower mid-level heights across the western CONUS
favors increasing chances for above-normal precipitation across a large portion
of the CONUS, aided in part by increased southerly return flow over the central
CONUS. This pattern sets the stage for multiple episodes of precipitation as
ejecting shortwave disturbances promote a favorable environment for enhanced
precipitation across much of the region, Below-normal precipitation is likely
over northern and central California as well as southern Florida, consistent
with the GEFS reforecast precipitation tool. Probabilities for near- to
above-normal precipitation remain elevated across Alaska. Near- to below-normal
precipitation is favored across Hawaii.

FORECAST CONFIDENCE FOR THE 8-14 DAY PERIOD: 3 out of 5, Average, due to good
model agreement regarding amplified ridging across the central CONUS and a
subsequent warmer pattern, offset by lack of forecast tools due to IT outage.

FORECASTER: Luke He

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.

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:
19621210 - 19851219 - 19601221 - 19561127 - 19531214

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:
19601223 - 19561127 - 19621211 - 20021124 - 19851218

6 TO 10 DAY OUTLOOK TABLE
OUTLOOK FOR APR 25 - 29, 2024


8 TO 14 DAY OUTLOOK TABLE
OUTLOOK FOR APR 27 - MAY 03, 2024


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 - ON AFOS AS
NFDPMDMRD.

$$