Area Forecast Discussion
Issued by NWS Caribou, ME-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KCAR 191516
Area Forecast Discussion
National Weather Service Caribou ME
1116 AM EDT Wed Apr 19 2017
High pressure will move east of the region today. A cold front
will pass through state tonight into Thursday.
.NEAR TERM /THROUGH THURSDAY/...
-- Changed Discussion --1035 AM Update: PoPs were re-done this aftn into tngt based on
fcst 6 hrly QPF, resulting in a slight delay of rnfl wording in
the fcst compared to last update. Also, more in the way of
dynamic cooling was played for with precip type ovrngt, meaning
more all sn by late tngt across the N and E cntrl ptns of the
FA. Fcst 6 hrly snfls were updated with most lctns across the N
and E Cntrl areas now fcst to receive 1 to 2 inches, being
somewhat trrn dependent. Otherwise, minor chgs to fcst hrly cld
cvr, sc temps and dwpts going into the aftn hrs based on latest
sat and sfc obs trends, with very little chg in fcst hi temps
from last update.
Orgnl Disc: Low pressure will approach from the west today as
high pressure continues to move off to the east of the state.
Precipitation is expected to spread across northern Maine from
west to east later this afternoon and tonight as over-running
takes place ahead of low pressure approaching from the west. The
precipitation will be mostly in the form of rain late this
afternoon and this evening but is expected to mix with and
change to snow across the north late tonight. The precipitation
will end mid morning as the low moves away. Have based the
precipitation type on surface temperature. Have created snow
ratio using the the snow ratio blender run on the NAM and using
the Cobb Tool. Snow amounts based on snow ratio. Have used
consensus raw for temperature.
-- End Changed Discussion --
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
Frontal occlusion wl be crossing the area at the start of the short
term on Thur mrng. Most of the steady pcpn wl hv pushed off to the
east by 12z with just sctd showers expected ahd of bndry. Expect
rain showers for Downeast and a rain/snow mix north of Houlton with
all snow showers up in the St. John Vly for a few hrs in the mrng.
H9 temps warm drg the day on Thu resulting in warmer maxes than Wed.
Next system wl begin impacting CWA late Thur night with H5 low
diving into the Great Lakes by 12z Fri.
Overrunning pcpn wl dvlp Fri mrng and continue thru the day. May see
snow at onset acrs nrn zones Fri mrng but as bndry lyr quickly warms
expect that rain wl be pre-dominant ovr most of the area by mid-
mrng. Sfc low then fcst to re-develop nr the Cape Cod vicinity late
Fri night. Model differences continue to abound on exactly where
this coastal low wl dvlp, with majority of med range guidance
indicating south of the Gulf of Maine sometime late Fri night yet
latest GFS continues to indicate along the Downeast coast by 06z
Sat. This closer soln gives much heavier qpf than rmndr of guidance
with GFS some 2-3 times higher.
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Sfc ridge axis builds in bhnd departing system drg the latter half
of the weekend. Expect a dry and warm day on Sunday with temps near
normal and light winds. Another chc for pcpn wl mv in Sun night as
cdfnt drops south out of Canada Sun night and sfc low heads up the
ern Seaboard at the same time. It appears that the front wl bring
the best chc for any pcpn as sfc low shoots out to sea tho cannot
rule out an isold shower acrs coastal zones. Overall a lochc for
pcpn anywhere acrs the CWA Sun night thru Mon.
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
NEAR TERM: Expect MVFR/VFR today and IFR tonight.
SHORT TERM: IFR expected Thur morning with restrictions
improving to VFR in the afternoon. VFR Thur night all terminals
before lowering to MVFR Fri morning with ocnl IFR through the
day in lower cigs. IFR Fri night acrs northern terminals in -sn.
Conditions will improve Sat aftn with VFR expected Sat night
into Sun all terminals.
NEAR TERM: Have used the NAM for sustained surface winds. For
Waves: The Nearshore Wave Prediction System was used for wave
grids. Current spectral observations from 44027 indicate that
easterly wind wave continues to be the primary waves system.
Longer period swell from the southerly fetch over the last few
days continues to persist as a secondary wave group. The
easterly wave group will subside later today as winds veer into
the southeast and develop a new wave system later today into
tonight. This new wave system will build to around 4 feet/5-6
seconds by later tonight and become the primary wave group.
SHORT TERM: Winds and seas will remain blo SCA levels through
Fri morning before increasing ahead of next system. Serly swell
will result in waves between 5-9 feet thru Sat morning as
coastal low tracks in vicinity of the Gulf of Maine.