Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Caribou ME
1041 am EDT Sat Apr 18 2015

low pressure will approach the region this afternoon 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/...
1015 am update...adjusted the sky conditions and temperatures to match up
current conditions. Decided to raise afternoon maxes up a few
degrees based on how things were taking shape as of the 10 am observation.
No other changes at this time. See hydrology section below.

Previous discussion...
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 /14z 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.


the ice jam on the Aroostook River near Washburn continues to
cause flooding. Some roads in the vicinity of Washburn remain
closed or or have water across them, but remain open west/one Lane.

The jam in Fort Fairfield moved downstream from the bridge with
levels remaining high. Portions of Riverside Ave had high water
across it.

Along the St. John river, an ice jam was still hung up from gradn
Isle down to the Van Buren Town Line. Law enforcement reported
some water running through the jam. No major flooding was
occurring just lowland flooding up toward the Allagash-St. Francis
Town Line.

Ice movement is expected to continue through the remainder of the
weekend. Ice jams will cause rapid fluctuations in river levels
and could lead to flooding with little to no advanced notice.


Car watches/warnings/advisories...
ME...Flood Watch until noon EDT today for mez001-002.



Near term...Farrar
short term...Bloomer/Hewitt
long term...Bloomer

National Weather Service Glossary of Abbreviations