Area Forecast Discussion
Issued by NWS Caribou, ME

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FXUS61 KCAR 190255

Area Forecast Discussion
National Weather Service Caribou ME
955 PM EST Sun Feb 18 2018

High pressure will crest south of the area tonight then move to the
east on Monday. A frontal boundary will form across the region
Monday night into Tuesday as warm high pressure remains to our
southeast and cold high pressure builds to our north.


940 PM Update: Changes this update again included cld cvr in
the now term and fcst hrly temps/dwpts and ovrngt lows into the
late ngt. Fcst winds were also lowered ovrngt spcly ovr broad
vly areas due to weak sfc pres grad flow with the late ngt apch
and erly morn passage of the sfc ridge axis.

A brief pd of ptly cldy skies and even a few flurries crossed NE
ptns of the Rgn earlier this eve, but these have moved E into NB
prov finally giving all of the Rgn clr skies late this eve. We
backed the arrival of hi cld cvr whose leading edge is now
traversing Cntrl QB prov about 2 hrs or so, resulting in a
little slower advc ovr our FA, but still xpct max cldnss to
occur ovr Nrn ptns of the Rgn at arnd 7 am or so.

Otherwise, fcst hrly temps and dwpts were updated into the
late ngt based on latest late eve obsvd hrly temps/dwpts. We had
to lower fcst ovrngt low temps this update spcly ovr the NW vly
lctns based on a few obs there already apchg prev fcst ovrngt
lows. The fall of temps should lvl off late tngt as the hi cld
shield arrives from QB.

Orgnl Disc: Low pressure that brought snow to portions of down
east Maine this morning continues to quickly move east out into
the open atlantic. Drier air was moving in behind the system
with clearing skies this evening as high pressure builds across
to our south. The high will move off the southern New England
coast late tonight with a light southwest return flow developing
toward morning. This will also bring an increase in high and
mid clouds toward daybreak Monday. Lows tonight will range from
the mid to upper teens north and lower 20s downeast.

High pressure continues to move east of New England on Monday
with milder air continuing to move across the region on
southwest winds. Along with the milder air will come an increase
in moisture during Monday with increasing clouds especially
Monday afternoon but the bulk of the daylight hours will remain
precipitation free. Highs on Monday will range from the mid to
upper 30s north and low to mid 40s central and downeast.


Warmer air on the back side of a high pressure system to our
southeast will be pushing up into the area Monday night as high
pressure builds into northern Quebec. A moist frontal boundary will
be forming in the convergence between these two highs, across our
area, Monday night into Tuesday. Some rain is likely across the
region late Monday night into Tuesday and the rain may mix with a
bit of sleet, freezing rain or snow over the far north where temps
will be close to freezing and some cooler air will push into the low
levels. The frontal boundary will remain stalled across the area
Tuesday night with occasional rain produced by convergence along
this front. Low pressure tracking north of the Great Lakes on
Wednesday will then lift the front north as a warm front on
Wednesday. Some of the warmest air so far this year will push north
into the region on Wednesday as skies remain mostly cloudy and some
rain showers continue over central and northern spots. Temperatures
may approach 60 Downeast and 50 over parts of the north on


Low pressure passing to our north will slide to the east Wednesday
night pulling a cold front across the region. This will bring some
showers, mainly across the Downeast area overnight Wednesday night.
Seasonably cold weather will follow with partial clearing on
Thursday as high pressure builds in from the west. High pressure
will build over the area Thursday night bringing a clear and cold
night. The high will crest over the region on Friday with a sunny,
tranquil and cool day. A return flow behind the high will bring
moisture, clouds and warming temperatures on Saturday as low
pressure lifts to our west. Another low may approach Sunday to bring
a chance of rain Downeast and rain or snow over the north.


NEAR TERM: VFR conditions through Monday. Winds will become
light and variable overnight and then turn to the southwest
during Monday.

SHORT TERM: IFR conditions are likely Monday night into Tuesday
as warm, moist air produces low clouds and some fog. IFR
conditions in low clouds will likely persist Tuesday night into
Wednesday, with a possible improvement to MVFR Downeast around
midday Wednesday. Conditions will likely be IFR Downeast and IFR
improving to MVFR then VFR across the north Wednesday night as
a cold front pushes through. Conditions should then return to
VFR everywhere on Thursday and be VFR in high pressure on


NEAR TERM: Winds/seas will continue to trend down this evening
and remain below SCA levels through tonight. Southwest flow will
bring increasing winds and seas beginning Monday afternoon and
an SCA has already been issued for Monday through Monday.

SHORT TERM: A SCA will likely be needed for southwesterly winds
gusting up to 30 kt early Monday night. Winds should decrease
below SCA late Monday night into Tuesday. Winds may then
approach SCA again on Wednesday, but should diminish again
Wednesday night into Thursday as a cold front pushes across the
waters. Winds should be light on Friday as high pressure crests
over the waters.


...N. Amer. Arctic Potential and Impact over Nrn and Ern ME...

It`s interesting to note that tdy is the last day of ami values
near 100 (pristine arctic air mass rating) ovr far Nrn Manitoba
prov Can with respective NAai and NDAai values of 40%/30%, with
the areal cvrg and core values of this air mass xpctd to modify
as it lifts ene into Nrn QB and then off the Nrn Labrador coast
ovr the next 1-2 days. Overall NAT values will cont arnd +0.5
durg this tm then begin to gradually modify to negative values
by next week. Although the overall initial NAT value is around
+0.5, substantial differences exist between NATw and NATe index
(indices derived from source rgn sectorized AO and ptns of the
TNH and EP-NP teleconnection patterns, respectfully) with NATw
around +2 and NATe -1 both accompanying a strong PNA- pattern.

Overall modification of arctic residency ovr Nrn N. Amer. by
next week will occur as TNH and AO/NAO all chg signs from
positive to negative and PNA becomes more neutral, resulting in
long fetch mid-trop Erly anomalous flow from the far N Atlc to
overtake much of the NAe and even ern ptns of the NAw source

The ovrall affect for Nrn/Ern ME will be after several
rn...mixed precip and sn events this week, drier conditions
may arrive by next week with any arctic air mass intrusions
of only low to mdt residence and relatively brief occurrences
( and


MARINE...Small Craft Advisory from 10 AM Monday to 5 AM EST Tuesday for



Near Term...VJN
Short Term...Bloomer
Long Term...Bloomer
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