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