Thursday, January 04, 2024

Winter/Spring Flood Potential Outlook For Northern And Eastern Maine - 01/04/2024

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WINTER/SPRING FLOOD POTENTIAL OUTLOOK
NATIONAL WEATHER SERVICE CARIBOU ME
912 AM EST Thu Jan 4 2024

...WINTER/SPRING FLOOD POTENTIAL OUTLOOK FOR NORTHERN, CENTRAL
AND DOWNEAST MAINE...

This is the first Winter/Spring Flood Potential Outlook for 2024,
issued by the National Weather Service in Caribou, Maine. This
outlook is for Northern, Central, and Downeast Maine for the two
week period of January 4th through January 17th, 2024.

The potential for ice jam flooding is Below Normal across
all basins with the lack of ice on the rivers. The potential for
open water flooding is normal across all basins with above normal
streamflows.

...NORTHERN BASINS...
SNOW DEPTH: Below Normal. 2-7 inches with isolated higher amounts
WATER EQUIVALENT: Below Normal. Generally 0.3-1.0 inch
STREAM FLOWS: Above Normal.
RIVER ICE: Mainly open water with frazil ice.

...CENTRAL HIGHLAND BASINS...
SNOW DEPTH: Below Normal. Trace-5 inches.
WATER EQUIVALENT: Below Normal. Generally Trace-0.5 inch
STREAM FLOWS: Much Above Normal.
RIVER ICE: Mainly open water with frazil ice.

...DOWNEAST BASINS...
SNOW DEPTH: Below Normal. No Snow up to 3 inches in interior areas.
WATER EQUIVALENT: Below Normal. Generally 0-0.5 inch
STREAM FLOWS: Much Above Normal.
RIVER ICE: Mainly open water with frazil ice.

For the 2024 season the ESF will be in graphical format on our
website www.weather.gov/car/springfloodoutlook with more details.

...CLIMATE GUIDANCE FROM NORTHEAST RIVER FORECAST CENTER...

A strong El Nino is in progress. The Oceanic Nino Index (ONI) sea
surface temperature departure (SST) in the Nino 3.4 region was +2.0C
as of January 2, 2024. This is slightly greater than the three month
September to November 2023 average SST departure of +1.8C. However,
some weakening of the positive SST anomalies is currently observed
across the eastern Pacific Ocean. The ENSO outlook indicates that El
Nino is expected to continue through March 2024 then a transition to
ENSO neutral conditions is favored between April-June 2024.

What`s been prevalent during December 2023 has been a split jet
stream pattern along with a strong El Nino which typically features
an active subtropical jet stream. The active subtropical jet stream
has resulted in periodic deep moisture occasionally lifting north
along the eastern seaboard into the northeast area with significant
precipitation...mostly rainfall along with milder temperatures
resulting in melt. In addition an active northern branch of the jet
stream has remained active although a weakly positive Pacific North
American (PNA) teleconnection typically promotes some ridging along
the west coast. The combination of a slightly negative Arctic
Oscillation (AO) and neutral Northern Atlantic Oscillation (NAO)
promotes some transient troughing to extend from the central CONUS
into the Northeast but with limited duration and scope of any cross
polar flow. Thus the active jet stream pattern has favored modified
pacific air and above normal precipitation to prevail across most of
the Northeast in December 2023.

Looking ahead the forecast trend is for the North Atlantic
Oscillation (NAO) and the Arctic Oscillation (AO) to turn more
negative. This would promote more blocking downstream which would
allow colder air to advect south with transient troughing extending
from the central Conus into the Northeast. However, the duration and
extent of cross polar flow remains to be determined as the Arctic
Oscillation (AO) is currently indicating some mixed signals heading
into mid January. During a strong El Nino the subtropical jet is
favored to remain active. The Pacific North American (PNA) pattern
is forecast to turn more neutral allowing for somewhat more
troughing along the west coast. Thus with a combined negative NAO
and neutral PNA...some individual storm tracks may be shunted
slightly further south with broad troughing present across most of
the CONUS...which may allow portions of Maine to be located
somewhat more on the northern low track side where more wintry
precipitation is favored. However, a mean trough located west of the
region would generally favor a more inland primary storm track which
generally favors more liquid precipitation and milder air across the
area. There currently remains uncertainty with individual
storm track solution details and outcomes regarding primary and
secondary low timing and development which will impact QPF amounts
and runoff.

$$

Sinko

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