Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Caribou ME
940 am EDT Wednesday Sep 2 2015
a cold front will approach later today...then cross the region
Wednesday night. High pressure will build across the area Thursday
Near term /through tonight/...
930am update: going forecast looks good for today. Tweaked sky and
temperatures to better match current conditions. May have to increase
probability of precipitation to likely across the far north if showers/storms become more
numerous than expected. But will do that in a later update to see
how convection evolves.
An upper level ridge is crossing the area early this morning with
widespread cirrus in northern zones. It will give way to an
approaching shortwave moving out of Quebec later today. The
shortwave will be accompanied by the surface cold front. Humidity
will surge today with dewpoints rising into the middle 60s. The big
question for today will be development of any convection. The
biggest problem is a lack of moisture as upper air analysis and
available upstream radiosonde observations show very little. Thus...sufficient
moisture for any convection will likely be confined to narrow
bands. As a result...have maintained no greater than chance probability of precipitation
through the period. This appears to be a two part event with
regards to convection. First...a pre frontal trough will move
into The Crown of Maine this afternoon. This trough will combine
with maximum heating and the elevated dew points to produce some
modest cape and the threat of isolated to scattered thunderstorms
in northern Aroostook this afternoon. 0-6 shear values and middle-
level lapse rates look reasonable for a few storms...but do not
see the need for any enhanced wording at this time. Highs today
will rise well into the 80s across the area with an isolated 90f
reading possible towards the lower Penobscot valley. The second
part of this event seems like it could unfold later in the evening
in central zones as the actual cold front arrives and the upper
shortwave amplifies. As a result...have followed the lead from the
cangems guidance and maintained probability of precipitation through the night as the
front works southward. Expect a warm and humid night across most
of the area with lows in the low to middle 60s and dew points also
remaining above 60f. By late night...drier air will arrive towards
the Saint John valley and continue to push southward through
Short term /Thursday through Friday night/...
cold front will have passed offshore by Thursday morning. Cooler and drier weather will
filter into County Warning Area drg the day with high temperatures only prognosticated to rise to
around 80f across interior downeast and struggling to hit 70f over the
far north. Dewpoints through the day will dip into the 40s across The Crown of
Hipres rapidly builds in Thursday night as 1025mb high settles across southern
Quebec. Dry northwest flow continues through Friday mrng, leading to clear skies overnight
with h9 temperatures dipping into the single digits. This will yield
widespread mins by Friday morning in the 40s with u30s not entirely out of
the question in the North Woods.
Surface high will settle over state of Maine Friday night with excellent radn'l
cooling conds. BUFKIT soundings for this timeframe show significant
Ridge/Valley split in min temperatures by Sat morning. 590 heights build in Sat
from the west which will result in a prolonged period of sunny skies and
warmer than normal temperatures.
Long term /Saturday through Tuesday/...
extended begins much the same way the same with a period of
sunny, dry and warm temperatures through the end of the weekend. 500 mb ridge
starts to flatten drg the day on Sunday with incrsg clouds across the
far north late Sun night and perhaps just a sprinkle or two in dry
airmass. Frontal boundary will be stretched just to the north of County Warning Area with
waves running along front in zonal flow. Frontal boundary will sag south
through the middle of the week with chance showers/tstms.
Aviation /14z Wednesday through Sunday/...
near term: VFR outside of scattered/isolated ts this afternoon and evening
ahead of a cold front. Fog may creep into bhb and coastal
terminals late tonight.
Short term: VFR through end of the weekend under extensive high
near term: fog is expected to return as very humid air moves over
the cold waters today.
Short term: cold front will cross waters on Thursday with pressure
gradient increasing Thursday night. This may lead to winds gusting to
over 25kts and possibly seas appchg 5ft. At this time, confidence
on Small Craft Advisory criteria being met is low.