Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Caribou ME
644 am EDT Sat Apr 18 2015
a small low pressure system will approach today and slide south of
the region this evening. High pressure will build in from the
northwest on Sunday. The high will move east Monday as a large area
of low pressure begins to approach.
Near term /through tonight/...
645 am update...
no changes needed to ongoing forecast at this time as precipitation should not
effect County Warning Area until close to 21z this afternoon. Still expecting north to
stay dry through the end of the near term. Only tweak was to bring
hrly T/dew point values closer to reality as North Woods dropped more
than expected as stratus never made it in from the north.
Previous discussion below...
Next shortwave to affect the County Warning Area later today is moving south of James Bay at
this time. Models agree on track of this WV sliding into northern New
England and eventually southern Maine by 00z tonight however they still
disagree on nwrd extent of quantitative precipitation forecast associated with impending system. GFS
continues to be the outlier when compared to NAM/ec, though latest hires
arw and nmm and latest rap, to a lesser extent, has trended north
with quantitative precipitation forecast shield. At this time, think that dry airmass will be hard to
overcome in enough time to justify probability of precipitation mainly north of a katahdin-
Danforth line. In general just expecting an increase in clouds over northern
zones with virga expected late afternoon/early evening hours.
Current temperatures have dropped down to right around freezing across northern zones in
cold air advection behind surface cold front now bisecting the state of Maine. Still expecting
morning mins to drop to right around 30f across northern counties with
interior downeast falling into the M/u 30s. Given cloud cover expected
today highs should only be able to climb into the u40s over The Crown of
Maine with m50s over southern sections of forecast area. These temperatures will be some 10-15
degrees cldr than yesterday though still right around normal values.
Forecast quantitative precipitation forecast values of 0.10-0.20 inches across southern and western zones as system
appears to be moisture-starved at this point. This is fortunate in
that liquid precipitation looks to fall in areas not affected by river ice.
00z models continue to indicate inverted trough keeping chance for
showers in through midnight perhaps ending as light snow showers across
northern Somerset County. Precipitation will be too quick to wind down and have foregone
any accums at this time. Mins will be in the u20s in the north under
mostly cloudy skies and l/m30s downeast.
Short term /Sunday through Monday/...
high pressure building down from the northwest will bring clearing
on Sunday bringing a mostly sunny and seasonable day across the
area. This will be followed by a clear and cool night Sunday night.
Our focus then turns to a large and complex low pressure system
approaching from the west. Clouds will increase Monday and rain will
likely spread into the downeast region by late in the day. Low
pressure will be located over the Great Lakes with a secondary low
forming in southern New England as the rain approaches on Monday.
Long term /Monday night through Friday/...
rain will push north Monday night and continue into Tuesday.
Thicknesses across the far north may be cold enough for a little
sleet to mix in early Tuesday. 850-700 thicknesses are warm enough
for rain but 1000-850 thicknesses suggest a bit of sleet is
possible over the far north. For the most part rain is expected
across the area. Rain will lift north of the region Tuesday night
and a push of dry air may bring some brightening on Wednesday.
Breaks of sunshine are possible, but clouds Wednesday will likely
fill in again as moisture circulating in the trough moves back
into the area. On Thursday another shortwave rounding the bottom
of the trough is expected to develop another area of low pressure
near southern New England. This will move north bringing another
round of rain later Thursday night into Friday. 850-700
thicknesses are much colder with this system, but 1000-850
thicknesses suggest mostly rain in all but far western areas. Snow
in northern and western areas will likely be very elevationally
dependent with the middle level thicknesses low and the air unstable.
Clouds and showers will likely continue into Friday with some wet
snow possible over highest elevations with the air continuing to
be cold aloft.
Aviation /12z Saturday through Wednesday/...
near term: VFR to start off taf valid time before MVFR
ceilings work in toward 02z across northern terminals. At bgr and bhb
expect MVFR restrictions in -ra toward 22z today. Bhb may
experience if ceilings after 00z Sunday.
Short term: VFR conditions are likely Sunday into early Monday.
Conditions will lower to MVFR later Monday then IFR on Tuesday.
An improvement to MVFR Tuesday night then VFR Wednesday is likely
before conditions drop to MVFR Wednesday night into Thursday.
near term: seas and winds expected to remain below Small Craft
Advisory criteria through tonight.
Short term: an Small Craft Advisory may be needed late Monday into Tuesday as low
pressure lifts north from southern New England. An Small Craft Advisory may be
needed again Thursday night as another low lifts north from the
Middle Atlantic States.
ice jam on the Aroostook River near Washburn caused flooding
resulting in several roads in the area to be closed. An areal
Flood Warning is in effect from Washburn to Presque Isle through
middle morning. The ice jam appears to have released but river levels
remain above flood stage at this time. Ice movement will continue
on the Aroostook and St John rivers along with tributaries into
Morning temperatures will dip to just below freezing and slow
snowmelt into middle morning. Ice movement expected to continue
through the weekend along with potential for ice jams. These jams
will cause rapid fluctuations in river levels and will lead to
flooding with little to no advanced notice.
ME...Flood Watch until noon EDT today for mez001-002.