National Weather Service United States Department of Commerce

Blizzard Conditions Over the Sierra Nevada Mountains; Critical Fire Weather in the High Plains

A strong winter storm across the west is currently producing heavy mountain snow, strong/high winds, and heavy low elevation rain to parts of the Pacific Northwest, Great Basin, California and the northern/central Rockies. Impacts are expected to continue through Sunday. Across the High Plains, strong winds and dry air will support Critical to Elevated fire weather conditions through the weekend. Read More >

NERFC Winter/Spring Flood Potential Outlook

View our routine five day flood outlook here.

 

 

Winter/Spring Flood Potential Outlook Graphic

Please note: if nothing appears on this screen, find the latest text outlook by clicking/tapping here.


000
FGUS61 KTAR 290038 CCA
ESGTAR

Winter/Spring Flood Potential Outlook
National Weather Service
Northeast River Forecast Center Norton MA
738 PM EST Wed Feb 28 2024

WINTER/SPRING FLOOD POTENTIAL FOR THE NORTHEASTERN U.S. /5/

The Winter/Spring Flood Potential for the northeastern United States
is near normal across the Adirondack Mountains in northern New York
State...the Green Mountains in central and northern Vermont and from
most of northern New Hampshire east into the mountains of western
Maine. The Winter/Spring Flood Potential is also near normal across
portions of coastal southern New England. Elsewhere across New
England and New York State...the Winter/Spring Flood Potential is
below normal.

The potential for flooding due to ice jams is near normal across
central and northern portions of Maine. The potential for flooding
due to ice jams is below normal across northeast Vermont...northern
New Hampshire and mountainous sections of western and central Maine.
Elsewhere across New England and for just about all of New York
State...the potential for flooding due to ice jams has passed for
the season.

...CLIMATE GUIDANCE...

After an incredibly warm first 10 days of February 2024...Arctic air
became re-established briefly during the middle of the month to take
the edge off what could have been record breaking monthly warmth.
Still...the cold has not been enough bring things back to near
normal. Through 26 February 2024...on average...temperatures have
averaged 4 to 8 inches above normal. The warmest temperature
departures have come across New York State where Syracuse and
Buffalo have averaged 8.5 and 7.8 degrees above normal respectively.
Burlington Vermont and Albany New York were also 6 to 7 degrees
warmer than normal through the 26th. Areas closer to normal included
coastal southern New England where Boston was 3.0 degrees warmer
than normal with Providence just 1.9 degrees above normal.

February 2024 has continued extremely dry although some 1 to 2 inch
rains will occur in spots today through tonight. Through 26 February
2024...melted equivalent precipitation was 2 to 3 inches below
normal across portions of southern and central New England. For
example...Portland Maine had just 0.27 inches of precipitation
through 26 February which was 2.99 inches below normal. And at
Boston`s Logan International Airport...the 0.42 inches of
precipitation through the 26th was 2.54 inches below normal. The
only places that will end up close to normal for the month will be
across Long Island and south coastal New England where monthly
precipitation totals will likely end up between 2 and 3.5 inches.

With the warmth and dryness of February 2024...it comes as no
surprise that snowfall for most places has been way below normal.
Through 26 February 2024...Syracuse New York had recorded just 6.6
inches of snowfall which was 21.6 inches below normal. Portland
Maine and Boston Massachusetts each had under an inch of recorded
snowfall through the 26th which is more than a foot below normal.
And...in a climate rarity...East Sandwich Massachusetts on Cape Cod
has reported 9.0 inches of snow during February 2024 which is so far
more than Buffalo New York...Burlington Vermont and Caribou Maine.

Again...the storm system today and tonight could bring some 1-2 inch
rains to the region which will end as some snow. This will be
followed by a brief shot of Arctic air. However...we are currently
under a positive North Atlantic Oscillation ( NAO ) Index and
negative Pacific North America ( PNA ) pattern. With a positive NAO
pattern...we typically see Arctic air intrusions short lived as the
lack of upper-level blocking downstream in the North Atlantic allows
cold air to quickly translate east. This is exactly what we expect
to happen over the next few days. And...with a negative PNA
pattern...southeastern United States upper level ridging typically
allows for a storm track near or west of New England which keeps the
region mostly on the warm side of systems. Again...this is textbook
to what we are seeing today with a large Low passing through
southeast Canada with warm southerly flow ahead of it.

There are signs that both climate indices will trend back towards
neutral as we move through the first 10 days of March but there are
no signs right now of any extended cold across the seven state
region of New England and New York State. In fact...NOAA`s official
8 to 14 day outlook for 6 to 12 March 2024 calls for temperatures to
very likely be above normal across all of the northeastern United
States. Precipitation for the same time period is leaning above
normal as well. If this forecast holds true...we may continue to
eradicate the already depleted snowpack and may not add much snow
outside of perhaps northern New York State and northern New England.

...OBSERVED SNOW DEPTHS AND WATER EQUIVALENTS...

The warmth and dryness of February 2024 has continued to allow the
snowpack to erode across the NERFC service area. Outside of central
and northern Maine where snow still blankets all areas...snow across
the remainder of central and northern New England and northern New
York State is mostly confined to the higher elevations. The snowpack
extent and depth seems to be about a month ahead of schedule and
would be more typical of one found in late March or early April.

...NEW YORK STATE...

In New York State...the only significant snow is found in the
Adirondack Mountain and Tug Hill Plateau regions of northern New
York State. Across the Tug Hill...snow depths below 1000 feet are
now patchy and just a few inches but near to just above a foot of
snow remains above 1500 feet in heart of the Tug Hill. Across the
Adirondack Mountain region of northern New York State...valley
locations are now averaging near or less than 6 inches of snow.
Above 1500 feet...however...8 to 16 inch snow depths do remain
common. Snow depths are well below normal for all areas of interior
New York State for the end of February except across the Adirondacks
where they are just below normal.

Along...south and west of the Mohawk River in New York State...there
is negligible snow water available for melt runoff. The same is true
across the Saint Lawrence Valley in far northern New York State.
East of Lake Ontario across the Tug Hill Plateau...snow water
equivalents average less than an inch in the valleys but rise to
between 1 and 4 inches above 1000 feet. East of the Tug Hill Plateau
across the Adirondack Mountain region...1 to 3 inches of water is
still held in the valley snowpack but those amounts increase to
between 3 and 6 inches above about 1500 feet. Much like snow
depths...snow water equivalents are way below normal across all
areas of New York State except the Adirondack Mountains where they
are just below normal heading into March.

...SOUTHERN NEW ENGLAND...

The ground is basically bare across southern New England now. The
only locations reporting snow are found above 1000 feet in the
Berkshire Mountains of western Massachusetts where 6 inches or less
of snow is found in shaded areas. This sparse snowpack contains at
most an inch or two of water. Both snow depths and water equivalents
are way below normal across southern New England for late February.

...VERMONT...

West of the Green Mountains in Vermont the ground is mostly bare
now. The same is true for the Connecticut River Valley in central
and southern Vermont. Across the Green Mountains as well as over the
Northeast Kingdom of Vermont...snow depths in the valleys average
near or less than 6 inches. These amounts increase to between 8 and
16 inches above 1500 feet with only isolated higher amounts. As of
26 February 2024...the snow depth below the summit of Mount
Mansfield was 58 inches which was about one-half foot below normal
at an elevation of 3900 feet. Outside of the highest elevations of
Vermont where snow depth is only a bit below normal...snow depths
across the Green Mountain state are well below normal for the end of
February.

There is little to no snow water available for melt runoff west of
the Green Mountains in Vermont to include the Champlain Valley. The
same is true for the Connecticut Valley locations in central and
southern Vermont. In the heart of the Green Mountains as well as
across the Northeast Kingdom of Vermont...1 to 3 inches of water is
held in the dwindling valley snowpack. These amounts increase to
between 3 and 6 inches above 1500 feet with only isolated higher
amounts. Snow water equivalents across Vermont are well below normal
for late February except over the highest peaks where they are
slightly below normal.


...NEW HAMPSHIRE...

Across southern portions of New Hampshire...only patchy snow is left
below 1000 feet. Near and above 1000 feet in southern New
Hampshire...snow depths do increase to between 6 and 12 inches.
Across northern portions of the Granite State...snow depths in the
valleys are near or below 10 inches but do increase to between 1 and
2 feet above 1500 feet with even higher amounts just below treeline
in the White Mountains. As of this morning...Hermit Lake
snowplot...at an elevation of 3749 feet...reported 32 inches of snow
on the ground. Apart from the White Mountains where snow depths are
a bit below normal...snow depths across New Hampshire are markedly
below normal for the end of February.

Across southern portions of New Hampshire...less than an inch of
water is available for melt runoff in the lower elevations but those
amounts do increase to between 1 and 3 inches near and above 1000
feet. From the White Mountains north to the Canadian border...snow
water equivalents are more impressive. Most valley locations in
northern New Hampshire report between 2 and 4 inches of water still
held in the snowpack. Those amounts do increase to between 4 and 8
inches above 1500 feet with isolated higher amounts across the
highest peaks. The one exception to this is found in the downslope
shadow west of the White Mountains around Whitefield and Lancaster
where there is less than an inch of water left in the pack available
for melt runoff. Snow water equivalents across New Hampshire are
much below normal outside of the White Mountains heading into March
and just a bit below normal in the White Mountains themselves.

...MAINE...

Within 20 or 30 miles of the coastline in Maine...snow depths are
running under 6 inches with bare ground common right along the
coast. Snow depths across interior downeast Maine average less than
6 inches. Across the remainder of Maine to include the
foothills...mountains...northwest logging woods and northeast potato
country...snow depths of 8 to 16 inches are common with higher
amounts mostly confined to areas above 1500 feet in the mountains
where up to 2 feet of snow is the norm. Snow depths are below normal
over the western mountains of Maine for late February.
Otherwise...snow depths across Maine are much below normal heading
into March.

An inch or less of water is held in the dwindling snowpack within 20
or 30 miles of the coast in Maine. Interior downeast Maine reports 1
to 2 inches of water in the pack. Across the remainder of Maine...to
include the foothills...mountains...northwest logging woods and
northeast potato country...snow water equivalents average 2 to 5
inches except above 1500 feet in the mountains where some spots
report 4 to 8 inches of water in the pack. Snow water equivalents
across the mountains of western Maine are below normal. Everywhere
else in Maine...however...snow water equivalents are much below
normal for late Winter.

...SOIL MOISTURE AND GROUNDWATER CONDITIONS...

The anomalously dry conditions that have occurred through most of
this February have allowed antecedent moisture states to decline
pretty significantly across New England and New York State.
Abnormally wet conditions that were once covering almost all of New
England and New York State about a month ago are showing signs of
contracting. As of 26 February 2024...near surface soil moisture
anomaly maps show abnormally wet conditions now confined to eastern
New York State and southern New England with the wettest conditions
shown across southeast New York State and Connecticut.
Conversely...below normal soil moisture states are now depicted from
the Finger Lakes area of central New York State west to the Lake
Erie shoreline.

Taking a look at the latest Palmer Drought Severity Index map from
24 February 2024...Extremely Moist conditions are still shown across
east central and southeast New York State as well as across much of
southern New England. This is the wettest possible category in the
Palmer Drought Severity Index and is not surprising since the Palmer
Index looks at moisture states on the span of weeks to months and is
still being influenced by excessively wet conditions that were seen
across New England and eastern New York State during December
2023 and January 2024.

Taking a look at groundwater monitoring wells across the region
courtesy of the United States Geological Survey ( USGS ) reveals an
overall net decrease in groundwater levels across New England and
New York State. Although most wells in New England and eastern New
York State are still near to above normal...very few are setting
record high monthly levels compared to January when numerous wells
were at all time monthly highs. Wells across eastern New York State
and New England at record high February levels were down to just a
handful including:

Tillson New York - 46 years of record
East Greenbush New York - 33 years of record
Eustis Maine - 22 years of record
Exeter Rhode Island - 42 years of record

Conversely...groundwater levels across western New York State have
continued to decline over the past month and now widespread below
normal levels are seen in monitoring wells from the Genesee River
Valley west to the Buffalo area. This coincides with the area of
abnormally dry and moderate drought conditions indicated in the
latest United States Drought Monitor map from 22 February 2024. We
also note that the large...deep aquifer across central Long Island
east of New York City is below normal but with shallow wells
generally in good shape we are not as concerned in that area.

...RESERVOIR LEVELS AND WATER SUPPLY...

Water supply reservoirs across most of New England continue to
average above to well above normal. Across New York
State...however...water supply reservoirs have dropped over the past
month and are now mostly near to even somewhat below normal. Across
northern New York State...Indian Lake has dropped to 3 feet below
its normal February pool level. However...Great Sacandaga Lake just
to the south was still more than 12 feet higher than its normal
February pool height. Hinckley Reservoir is now 4 feet below normal
heading into March. Nearby Stillwater Reservoir was closer to normal
as of 27 February 2024...coming in around 1 foot lower than its
normal pool. Owasco Lake in central New York State is now running
about 0.6 feet below its normal February level. And in northeast New
York State...Lake Champlain continued to decline over the past few
weeks but is still about 1 foot above its normal level for February.

Across southeastern New York State...the New York City Water Supply
System...comprised of 7 large reservoirs...was at 94.1 percent of
capacity as of 26 February 2024 which was 3.3 percent above normal.
1 of the 7 large reservoirs comprising this system was above
capacity and spilling water uncontrolled over its outlet works
compared to 5 above capacity one month ago.

In northern New England...reservoir systems in the Kennebec River
Basin in Maine were 60.4 percent full as of 26 February 2024 which
was 35.5 percent above normal. The nearby Androscoggin River storage
was 53.9 percent full which was 38.7 percent above normal. Storage
on the West Branch Penobscot River was 53.4 percent full which was
25.8 percent above normal. Lake Winnipesaukee...New Hampshire`s
largest lake...reported a recent level close to normal after more or
less continued dumping of water over the past 2 weeks. Just 2 weeks
ago...Lake Winnipesaukee was at a record high daily level. In far
northern Vermont...Lake Memphremagog in Newport was running very
close to its normal pool level for the month of February.

Across southern New England...Quabbin Reservoir...the main water
supply reservoir for the Boston Metropolitan area...was at 98.6
percent of capacity as of 1 February 2024 which is in the normal
operating range. The smaller Wachusett Reservoir was also in the
normal range for February...at 91.9 percent of capacity. Scituate
Reservoir...the main water supply reservoir for northern Rhode
Island including the city of Providence...was at 285.1 feet as of 27
February 2024. This was 104.4 percent of capacity. Water at this
level is flowing over the spillway uncontrolled into the mainstem
Pawtuxet River.

In general...we do not anticipate large scale water supply issues
heading into Spring. However...there are some areas of
concern...particularly across western New York State in the Genesee
Valley and Buffalo Creek regions where below normal groundwater
levels and the current lack of snowcover for recharge could lead to
supply issues unless we see above normal precipitation amounts
through Spring. Also...low groundwater levels and long term
precipitation deficits have some concern for water supply on
Nantucket Island in southeast Massachusetts if we dont see above
normal rainfall late this Winter and Spring. Recent
readings...however...do show some slight improvement to groundwater
levels on Nantucket.

...RIVER AND ICE CONDITIONS...

River and stream flows are near to above normal across most of New
England and New York State with the exception of western New York
State near and east of Buffalo where they are below to much below
normal. Flows are also dipping below normal across a lot of central
and northern Maine. Flows are highest across coastal southern New
England where 1 to 2 inches of rain fell over the past 24 hours. In
fact...portions of the Wood River in southern Rhode Island could
approach flood stage over the next 24 to 36 hours. Out in western
New York State...flows are lowest across the lower Genesee
River...Oatka Creek...Black Creek and Tonawanda Creek watersheds
where flows in some instance were in the lowest 10 percent of the
historical record for 28 February.

River ice remains thin across portions of northern Vermont and far
northern New York State and is only marginally thicker across
northeast Vermont and far northern New Hampshire. Ice in these areas
is thought to be less than 6 inches thick and fairly rotted. Recent
web cams show the ice has moved out of coastal Maine rivers like the
lower Androscoggin...lower Kennebec and lower Penobscot.

Across central and northern Maine...however...Arctic air over the
past 2 weeks has actually allowed for ice to thicken up. Reports
from northern Maine indicate 12 to 18 inch ice thicknesses on the
upper reaches of the Saint John River above Dickey with nearly 100
percent ice cover. Reports along the Aroostook River in northeast
Maine indicate 8 to 16 inch ice thicknesses with rot beginning to
appear on the edges of the ice sheet. In north central Maine...the
East Branch Penobscot and Mattawamkeag Rivers were mostly ice
covered with thicknesses up to around a foot. In general...the ice
in the above mentioned areas is not as structurally sound as would
normally be expected in late February. It is beginning to soften due
to the recent mild weather and increasing incident solar radiation.
Further south in Maine...there is still some ice along reaches of
the Piscataquis...Carrabasset and Sandy rivers but thicknesses in
these areas is generally near or under 6 inches.

Across central and southern New England and all of New York State
outside of the northern Adirondacks and far northern Saint Lawrence
Valley...river ice is virtually non-existent and will not be able to
reform this season due to increasing solar radiation.

There are currently no known ice jams on rivers or streams in the
NERFC service area.

...IN CONCLUSION...

Based on the information available at this time...the Winter/Spring
Flood Potential for the northeastern United States is near normal
from the Adirondack Mountain region of northern New York State east
across the mountainous terrain of central and northern
Vermont...most of northern New Hampshire and into the mountains of
western Maine. In these areas...the next few weeks will likely
feature above normal temperatures which will begin steady snowmelt.
And even though snow depths and water equivalents are below
normal...there is still adequate snow to provide significant runoff
into rivers and streams. This will leave the region somewhat
vulnerable to flooding if a heavy rainfall event develops over the
next few weeks. The medium range climate outlook does favor above
normal amounts of precipitation over the next 2 weeks so the flood
threat is deemed high enough to justify a normal threat as we head
out of February into the first one-half of March. It is important to
note that the longer term flood threat for Spring is actually below
normal right now due to lack of snowpack. Within this area...we were
quite concerned for the potential for flooding on Lake Champlain due
to very high levels in January. However...February`s dry weather
with below normal snowfall has allowed Lake Champlain to subside to
just a bit above normal now. Consequently...we are now moving the
flood potential for Lake Champlain back to normal going forward.

The Winter/Spring Flood potential is also near normal across
portions of coastal southern New England. In these areas...river
flows are above normal and groundwater is high. In addition...most
reservoirs are already above normal. Rainfall from last night and
today will push some rivers like the Wood River in southern Rhode
Island to near flood over the next 24 to 36 hours. Numerical weather
model guidance shows the potential for some additional heavy
rainfall over the upcoming weekend and possibly more later next
week. Despite the lack of snow on the ground...these wet antecedent
conditions warrant a near normal threat for flooding over the next 2
weeks.

Across the remainder of New England and New York State...the
Winter/Spring Flood Potential is below normal. These areas include
all of New York State outside of the Adirondack Mountains...interior
southern New England...portions of southern Vermont and southern New
Hampshire and all of Maine outside of the western mountains. In
these areas...the lack of snowcover is the defining feature
justifying a below normal flood threat. Even across central and
northern Maine where there is some snow water available for
melt...river flows and groundwater levels have actually decreased to
near and in some cases below normal. These areas are not getting
heavy rainfall from the event today so flows will not be elevated
heading into the next few weeks. It would likely take more than one
heavy rainfall event over the next 2 weeks in these areas to cause
flooding which is not something we currently see in any medium range
numerical weather guidance. Without significant runoff in the
forecast...not even a normal threat for flooding in these areas can
be justified. In fact across much of western New York State...we are
becoming more concerned with an emerging drought threat than a flood
threat right now.

The potential for flooding due to ice jams is near normal across
much of north central and northern Maine. In these areas...river ice
has actually thickened and become more established over the past 2
weeks due to an Arctic air intrusion. 12 to 18 inch ice thicknesses
are common on the upper reaches of the Saint John...Allagash and Big
Black Rivers with 8 to 16 inch thicknesses a bit farther east and
southeast on rivers like the Fish...Aroostook...East Branch
Penobscot and Mattawamkeag. Although the ice is not as structurally
sound as would be expected in late February with rot beginning to
appear...it is still plenty thick to cause ice jamming if increased
runoff causes it to move and break. With the next few weeks likely
featuring above normal temperatures with increasing flows...we
cannot rule out ice movement...especially along the Penobscot and
Mattawamkeag Rivers. Further north...we tentatively think the ice
will hold another 2 weeks along the northern most rivers. With all
this in mind...a near normal threat for ice jam flooding for early
March seems justified in these areas.

From northeast Vermont and far northern New Hampshire eastward into
the western and central highlands of Maine...the potential for
flooding due to ice jams is below normal. In these areas...river ice
is much thinner...generally at or below 6 inches thick along the
Piscataquis...Carrabassett and Sandy river watersheds in Maine and
the Passumpsic and upper Connecticut watersheds in Vermont and New
Hampshire. In addition...most of these rivers are already partially
to mostly open. River ice could absolutely flush and move over the
next 2 weeks in these areas but we do not think it is structurally
sound enough to hold back significant amounts of backwater in a jam
and would likely just buckle and quickly move downstream if a jam
tried to form. For this reason...a below normal threat for ice jam
flooding is deemed to exist in these areas.

For the remainder of the region to include coastal Maine...central
and southern portions of both Vermont and New Hampshire...all of
southern New England and all of New York State...the potential for
flooding due to ice jams is well below normal or has passed for this
season. Any remaining ice across far northwest Vermont and far
northern New York State is so thin that we don`t think it causes any
realistic ice jam threat going forward. And for the rest of this
area...river ice is pretty much non-existent and will not be able to
reform this season due to increased incoming solar radiation.

It is important to remember that very heavy rainfall can result in
flooding at any time of year...even in areas that have little or no
snow on the ground.

A graphic depicting the flood potential across the NERFC service
area is available on the NERFC web site at

*** www.weather.gov/nerfc/springfloodpotential ***

The next Winter/Spring Flood Potential Outlook will be issued by the
NERFC on Thursday 14 March 2024.

End/Horwood
$$

Local NWS Office Flood Outlook Discussions:
(check the date near the top of each product to ensure it is current!)

    Albany, NY  

    Binghamton, NY  

    Brookhaven, NY  

    Buffalo, NY  

    Burlington, VT   

    Caribou, ME  

    Gray, ME   

    Norton, MA 

NERFC Snow Page

Precip Departures from Normal

Cold Season Self Briefing Page

To view long-range probabilistic guidance at our river forecast locations, use the following directions:

  1. Visit our main page at https://www.weather.gov/nerfc
  2. Click on the circle icon for the river forecast point you wish to view.
  3. On the next page, hover over the tab near the top labeled Probability Information
  4. There are three options shown.
    1. The first, Weekly Chance of Exceeding Levels, gives a week-by-week probability of exceeding certain values over the next 90 days.
    2. The second, Chance of Exceeding Levels During Entire Period, combines these into a single graphic over the 90 day period.  The easiest way to read this second graphic:  if the black line is above the blue line, the probability of reaching a given stage/flow is higher than normal for the time period.  You can also follow the black line to a given value to see the probability of that value occurring.

Note:  All our probabilities are based on natural flow, without any ice effects.  Ice effects may cause flooding even when natural flow is limited.