Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Caribou ME
818 PM EDT Monday Sep 1 2014
a cold front will approach later Tuesday...then cross the region
Tuesday night through early Wednesday. High pressure will follow
behind the front for the late week.
Near term /through Tuesday/...
8 PM update: latest radar imagery indicates that thunderstorms dissipated
leaving isolated to widely scattered shower activity msly across western and southern
portions of the forecast area. Thunderstorms were eliminated from the forecast grids for the
rest of the evening and probability of precipitation were adjusted based on this covering. Otherwise
hrly forecast cloud cover and temperatures were adjusted for the overnight based on
latest Sat and surface observation. Forecast overnight lows remained unchgd at this time.
Orgnl disc: an upper level disturbance will be exiting the region
at the start of the near term period of the forecast. A weak ridge
of higher pressure will build in tonight into early
tomorrow...before another cold front moves into western Maine by middle
day tomorrow. The GFS...ECMWF...Gem...and NAM are in good
agreement on position and movement of the weather trough the near
term period. All are placing a weak surface low over eastern
Washington County at the start of the period...this is a
reflection of the upper level short wave that tracked through
Maine today. A ridge of higher pressure with the high centered
over eastern Quebec will build into northern Maine behind the low. Showers
will taper off after sunset...patchy fog will again develop over
much of the area overnight into tomorrow morning. Low stratus
clouds will hang around through the morning hours...then begin to
burn off in the afternoon providing mostly sunny downeast...partly
sunny central and north early afternoon. High and middle clouds
will be moving into the area in advance of the next front that
will be into western Maine early afternoon.
Loaded a blend of GFS/ECMWF/Gem/NAM for hrly
temperature/Max/min/wnd/sky/pop added 15 percent to winds for gusts over
land...25 percent over coastal waters. Loaded nawave 4 for seas in
the coastal waters.
Short term /Tuesday night through Thursday/...
a cold front and an associated upper disturbance will move through Tuesday
night from west to east bringing showers and thunderstorms. Models
depict precipitable water values of 1.5 to 2.0 inches along with
strong upper dynamics so raised quantitative precipitation forecast amounts for Tuesday night over
the north where the forcing is the strongest. Generally expect a
quarter to half inch of liquid over northern areas, with locally
higher amounts, with a tenth to a quarter inch in the south with
through Tuesday night. However due to the fairly fast movement of the
front not expecting any Hydro issues. Any lingering showers over
eastern area quickly come to an end Wednesday morning. Otherwise
expect a mix of sun and clouds for Wednesday with breezy
conditions and highs in the 70s to around 80 over interior
A ridge of high pressure drifting south of the region will be the main
weather player for the area for Wednesday night and Thursday.
Conditions will be mainly clear to partly cloudy with lows
Wednesday night in the upper 40s to middle 50s and highs Thursday once
again in the 70s to around 80.
Long term /Thursday night through Monday/...
high pressure will set up south of the area Thursday night into
Friday with a low passing by well to the north. This will set up a
warm SW flow with highs Friday jumping into the low to middle 80s. A
cold front will approach late day from the northwest bringing a
late day chance of showers and thunderstorms to northern areas.
However the better chances for more widespread showers and storms
occurs Friday night as the front pushes south into the region.
Forecast models begin to diverge heading into the weekend as to whether
the above mentioned front pushes south of the area resulting in
clearing vs. Stalling out with a new wave of low pressure riding
northeast along it. This latter solution would result in more
rain and showers by later Saturday into Saturday
night...especially south. Utilizing our long range model blend
procedures, we keep chance probability of precipitation in the forecast through Saturday
night with the best chances of precipitation occurring over southern
Expect conditions to become mainly dry but cooler for Sunday and
Monday as high pressure moves in.
Aviation /22z Monday through Saturday/...
near term: MVFR conditions for bgr...bhb this afternoon...becoming lmvfr
conditions in showers at bgr. Conditions will fall to LIFR by
morning in fog. Lmvfr conditions for hul...pqi...car...and fve
with scattered showers and isolated thunderstorms. Thunderstorm most likely between bgr
and hul early in the period. Conditions will fall to LIFR in fog
from late this evening to early tomorrow morning. Lmvfr middle
morning...MVFR to VFR late morning in advance of the next front.
By the end of the period the next front will be into
fve...bringing another round of lmvfr to IFR conditions with
Short term: showers and storms will result in MVFR/IFR conditions
Tuesday night with improvement to VFR for Wednesday and Thursday
as the front sweeps east and high pressure moves in. The next cold
front moving through Friday night will once again bring the
potential for reduced ceilings/visible with the possible MVFR/IFR conditions.
near term: winds and seas below Small Craft Advisory criteria through the period.
Short term: the main concern for Tuesday night will be fog along
with showers and potential thunderstorms moving across the waters
in association with a cold front. However winds/seas look to
remain below Small Craft Advisory levels. Showers/storms move east by Wednesday
morning with high pressure building in for later Wednesday into
Thursday over the waters.