Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Caribou ME
127 am EDT Sat Aug 1 2015
a weak ridge of high pressure will build across the area overnight.
Upper level disturbances crossing the region will keep unsettled
conditions through the weekend with scattered showers and
Near term /through Saturday/...
115 am update...adjusted the probability of precipitation through 12z to bring 20% across
the west and northwest areas. The latest hrrr 3km model matched up west/the
latest radar trends bringing light returns(25-30dbz) across the
aforementioned areas early this morning. Weather element will be light
showers. Infrared satellite imagery showed some clouds moving across Quebec
toward west-northwest areas. Observation and ceiling plots indicate cloud deck
between 5 and 8k feet. 05z surface analysis had weak ridge moving east
west/weak cold front moving toward Quebec. Temperatures were adjusted as
well to match the latest conditions.
Generally expect partly cloudy/mostly clear skies across northern
portions of the forecast area overnight...though cloud cover will
begin to increase across northwest areas late in advance of the
approaching upper disturbance. Mostly clear skies will occur
across the rest of the forecast area overnight. Overnight low
temperatures will range from the upper 50s to around 60 across the
forecast area. Have updated the forecast to adjust for current
conditions along with expected overnight temperatures and cloud
The focus for Saturday deal west/upper trough & cold frontal
passage. Expect showers and thunderstorms to develop along and
just ahead of the surface front/wind shift line early in the
afternoon and then shift southeast through the evening hours. It
looks like things should fire up a little earlier than previously
anticipated, with showers and thunderstorms moving into the far
northwest by early afternoon and into interior downeast by early
evening. 0-6km shear looks good at 40-45 kt, along with middle-level
lapse rates 5.5-6.5 c/km. Although some of the models indicate sb
convective available potential energy of 1100+j/kg, this is likely overdone and the more modest
600-1000 j/kg seems more reasonable. This along with a dry layer
aloft could serve to limit severe potential. The biggest threat
would be hail given the cold air aloft, though gusty winds will be
possible in any storms that are able to tap the stronger winds
aloft. This thinking follows closely with spc, which has continued
to include all of interior Maine in a marginal severe risk in
their latest day 2 outlook. Have therefore kept enhanced wording
in tomorrow's forecast.
Short term /Saturday night through Monday/...
unsettled weather will continue across Pine Tree state...with a
weak shortwave affecting our County Warning Area on Sunday...and then a strong
upper low swinging eastward across New England. The features will
produce their own round of showers and thunderstorms...with the second
having more widespread and heavier precipitation. Temperatures will be
seasonably warm with highs ranging from the middle 70s to the lower
Long term /Monday night through Friday/...
a trough digging into eastern Canada will set the stage for some
cooler weather coming in during the middle week period. A cold front
coming through Monday night will bring a chance for showers and
scattered thunderstorms. The air behind this cold front will only
be slightly cooler and drier on Tuesday. Significantly cooler air
will then filter into the area Tuesday night into Wednesday as a
trough of low pressure begins dropping southeast across Quebec.
Some isolated showers will be possible across the north on
Wednesday. The trough will begin to lift away to the northeast on
Thursday allowing for a dry day with sunshine and temperatures a few
degrees below normal. Dry weather may last into Friday before a
deeper and stronger trough approaches over the weekend bringing a
chance for showers Saturday then a trend toward cooler conditions
Sunday into Monday.
Aviation /05z Saturday through Wednesday/...
near term: VFR conditions are expected overnight into early
Saturday. However...showers and thunderstorms will develop by
early afternoon along a cold front and cross from northwest to
southeast during the afternoon/evening. MVFR and even local IFR
conditions will be possible in any convection along with gusty
winds and small hail.
Short term: scattered showers and thunderstorms are expected
across much our forecast area Sunday and Monday. Reduced ceilings and
visibilities will probably accompany the stronger showers and storms.
Also...strong winds...frequent lightning and heavy downpours are
possible with the stronger storms on Monday.
near term: winds/seas will remain below Small Craft Advisory
levels overnight through Saturday.
Short term: winds and wave heights will stay below Small Craft Advisory criteria
during Saturday night through Monday. However some thunderstorm
activity may affect coastal marine zones on Monday.