NWS Forecast Discussion

For Fremont, NH

FXUS61 KGYX 180811

Area Forecast Discussion
National Weather Service Gray ME
311 AM EST Sun Nov 18 2018

A cold front will exit the area early this morning. A weak ridge
of high pressure will briefly build into the region today before
sliding offshore. A weak area of low pressure will track across
southern New England and the Gulf of Maine tonight into the day
Monday. This disturbance will produce a light snowfall from
southern New Hampshire across the coastal plain of Maine late
tonight into the day Monday. Another area of low pressure
will pass south of the region Tuesday. An Arctic front will
cross the region Wednesday, followed by high pressure building
into the region through the end of the week.


At 06z...a cold front extended from the Gulf of Maine into
southwest Maine and southern New Hampshire. a 1028 millibar
ridge was over the eastern Great Lakes. The front will press a
bit further south this morning before stalling across southern
New England. The weak ridge will slide quickly east and we`ll
see at least a few sunny periods before the ridge retreats
offshore by afternoon. By afternoon...the front and a weak
surface low begins to press back north and east accompanied by
increasing warm air advection cloudiness. It`ll be another below
average day in the temperature department...with highs ranging
from the 20s across the mountains to the lower and mid 30s


A shortwave impulse races eastward in broad cyclonic west-
southwest flow tonight and early Monday. The associated surface
low will track along the frontal boundary across southern New
England and into the Gulf of Maine during that time. Light warm
air advection precipitation develops overnight mainly south and
east of the mountains and foothills. The column is sufficiently
cold enough for snow and most locations in southern New
Hampshire and along the Maine coastal plain see a dusting to an
inch by dawn on Monday. The snow tapers quickly from southwest
to northeast during the day as the upper impulse and weak
surface low quickly exit into the maritimes. Additional
accumulations will range from a dusting to an inch...for total
accumulations ranging from a dusting to as much as two inches.


The long term headlines feature another chance for light
accumulating snow on Tuesday, and then a very cold

On the hemispheric scale, the high amplitude blocking hold
through the week with strong rex block over Europe allowing the
trough to deepen over ern NOAM. There is a trend in the models,
especially the Euro, for less amplified flow by next week with
a higher wave number, which will take the core of the cold air
off the pole and Hudson Bay and spread it more evenly among the
continents, which should allow for some warming over New

Mon night will see a break in any action with some clearing as
cold front moves thu, and lows generally in the 20s. The front
stalls to our south on Tuesday, with another weak wave
developing along the front. Will be discounting the operation
GFS at this point, and going with something of a blend between
the 00Z GEFS/ECMWF/NAM/CMC, which bring another round of light
snow, and rain in srn NH on Tue. Models show diffuse jet dynamic
forcing and dry airmass, but the trough does get some 500 mb
energy and is riding along a mid lvl baroclinic zone, and
therefore forecast confidence is low, but highest QPF is in srn
NH and on the ME coast. Highs Tue will range from the upper 20s
to low 30s in the N to the mid-upper 30s in the south.

Any precip will wind down late Tue and some clearing will occur
behind the system as winds shift to W and bring some colder air
in, with lows mostly in the teens, with lows 20s in srn and the
ME coast.

Wed will feature the passage of the arctic front, mainly from
NW-SE during the afternoon. Highs should get into the 30s again
ahead of the front, bit will likely see temps fall behind the
front, mid-late afternoon in the north, and during the evening
in the south. Could see some SHSN and even some squalls in the
mtns Wed afternoon, but this becomes less likely, but completely
out of the question toward the coast and in srn NH, as air mass
ahead of this front will already be cold and dry. The question
will be how much moisture and warming will occur in SW flow
ahead of the front before the front moves through. We night will
see NW flow pick up a pick up behind the front and bring the
cold air in, with lows dropping to 5-10 in the N and 10-15 in
the south. Thanksgiving will be quite cold and windy (gusts of
25-30 mph at times and highs only in the 15-25 range, for the
most part. This will produce daytime wind chills of zero to 15
above from N to S.

The sfc low will continue to intensify over the maritimes, as
the sfc high pushes in from the west, which will help maintain a
pres gradient into Friday, which will keep the winds going,
though somewhat less than on Thu. Thu night lows will range from
zero to +5 F in the mtns to 10-15 in the south, with wind
chills dropping to 5-10 below in the mountains and to near zero
in the south. Friday will be slightly warmer, as core of
coldest air will pass Thu night, but still highs still well
below normal, 20-25 in the mtns to around 30 in the south.
Sat looks  dry and warmer, with mainly sunny skies.


Short Term /Through Monday/...VFR. Conditions lowering to MVFR
btw 02z and 08z Monday in -SN with lcl IFR psb at southern NH
and coastal ME terminals. Conditions improve to VFR btw 14 and
18z Monday from SW to NE as -SN ends.

Long Term...Possible period of MVFR-IFR in SN/RA on Tuesday, but
should see mainly VFR Wed-Thu. Could see NW wind gusts approach
25 kt on Thu.


Short Term /Through Monday/...Winds and seas will continue to
drop off as weak ridge builds eastward today. A weak low will
cross the Gulf of Maine late tonight and Monday with vsby
restrictions in -RA/-SN and fog. However...winds and seas with
this disturbance are expected to remain below SCA threshold.

Long Term...SCA likely will be needed Wed night into Thu, with
a period of gales possible.





NEAR TERM...Schwibs
SHORT TERM...Schwibs

NWS GYX Office Area Forecast Discussion