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Area forecast discussion 
National Weather Service Taunton Massachusetts
631 PM EST Friday Feb 27 2015

Synopsis...
high pressure slowly building in from the west will bring dry but
unseasonably cold weather into Sunday morning. A low pressure system
will bring a plowable snow late Sunday and Sunday night. Another
storm is likely Tuesday night into Wednesday...with snow and mixed
precipitation likely changing to rain. Cold and dry conditions
return for the end of next week.

&&

Near term /until 6 am Saturday morning/...
630 PM update...
skies are clear across the region. Updated T/dew point grids for current
trends otherwise forecast on track.

Previous discussion...
high pressure continues to build in providing excellent
radiational cooling conditions across southern New England. Low
temperatures were a blend of the NAM and GFS 2 meter temperatures...
resulting in lows between 5 and 15 below zero in the western
locations and 0 to 10 degrees across the eastern zones.

&&

Short term /6 am Saturday morning through Saturday night/...
Saturday and Saturday night...high pressure remains in control of
the region. Despite a frigid start to the day...temperatures will
rebound into the middle to upper 20s Saturday afternoon. Light winds
and the higher sun angle will aid in it feeling a bit more
tolerable despite temperatures remaining well below normal. Another cold
night is expected Saturday night with excellent radiational
cooling.

&&

Long term /Sunday through Friday/...
highlights...

* plowable snow likely late sun/Sun night...clearing Monday
* another storm possible Tuesday night into Wednesday...with snow or
mixed precipitation likely changing to rain
* cold and dry toward the end of the week

Sunday...
high pressure moves off the coast during the afternoon with developing
warm advection pattern resulting in sunshine quickly giving way to
increasing clouds. Some uncertainty on timing of leading edge of
snow and how quickly the column moistens. Some light snow may
develop by late afternoon. Maximum temperatures upper 20s to lower 30s.

Sunday night...
models similar with low pressure tracking across central new eng late
Sun night...with some hint of a weak low level circulation
developing south of the coast. Good overrunning signature with a
period of middle level fgen and decent precipitable waters will bring a slug of
precipitation into southern New England Sun night. Thermal profiles cold enough for all
snow...except perhaps for the islands where boundary layer warming
may eventually force a change to rain.

Models in good agreement on quantitative precipitation forecast with 0.25"-0.50"+ from north to
south...heaviest along the South Coast. Cross sections do show a
period of decent snow growth with maximum Omega nudging into -10c layer.
Generally expecting a good advisory event with 3 to 6 inches with
maximum snow aligned along and south of the Mass Pike but inland from
the S coast where slr may be lower due to bl warming. A few locally
higher amounts cant be ruled out across north CT...north Rhode Island and adjacent southeast
Massachusetts. The system is progressive and bulk of snow should be moving out
before the Monday morning commute.

Monday...
some lingering light snow possible in the morning...otherwise mainly
dry as deepening low pressure moves into the Gulf of Maine with good middle
level drying moving into the region. Expect clearing skies in the
afternoon but becoming blustery with northwest winds gusting to 35 miles per hour. Maximum
temperatures in the 30s.

Monday night into Tuesday...
high pressure builds in from the west. Gusty winds Monday evening will
gradually diminish later Monday night into Tuesday as the ridge crests over
new eng. Temperatures below normal.

Tuesday night into Wednesday night...
models in agreement on deepening low pressure moving up through the
lakes with not much hint of secondary low development. With low
level S/SW flow it will be very difficult to lock in the cold air so
an eventual change to rain is expected...quickest along the coast
Tuesday night...but European model (ecmwf) is quite a bit colder than GFS on the front
end of the storm Tuesday night and would suggest a decent accumulate of
snow/ice in the interior before going to rain Wednesday. GFS would
suggest a fairly rapid transition from snow to rain Tuesday night. Due
to uncertainty we blended the GFS/European model (ecmwf) partial thicknesses and have
precipitation starting as snow everywhere Tuesday night then transitioning to a
mix/ice overnight in the interior with rain along the coast...then
all rain Wednesday. Snowpack will be able to absorb the rainfall and other
than areas of poor drainage flooding due to clogged
drains...flooding is not anticipated.

The other item of uncertainty is how quickly the rain exits. GFS is
most progressive and dries it out Wednesday night...while European model (ecmwf) has more
amplified upstream trough which slows the front down with potential
frontal wave bringing another period of rain Wednesday night into early
Thursday. Consensus of the guidance favors European model (ecmwf) solution. Still lots of
uncertainty this far out and how this plays out will affect forecast
pops/temps/ptype. A solution closer to European model (ecmwf) would result in milder
temperatures Wednesday night with more rain.

Thursday and Friday...
precipitation could linger into Thursday morning if European model (ecmwf) solution is
correct...but trend through the end of the week will be for colder
and dry conditions with temperatures dropping well below
normal...especially Thursday night and Friday.

&&

Aviation /23z Friday through Wednesday/...
forecaster confidence levels...

Low...less than 30 percent.
Moderate...30 to 60 percent.
High...greater than 60 percent.

Short term /today through Saturday afternoon/...

Tonight through Saturday night...high confidence. VFR

Kbos taf...high confidence. VFR.

Kbdl taf...high confidence. VFR.

Outlook...Sunday through Wednesday...

Sunday...high confidence. VFR...then ceilings/visibilities lowering to MVFR
later in the afternoon from west to east as light snow overspreads
the region.

Sunday night...high confidence. IFR in periods of snow. Expecting 3
to 6 inches at area terminals...less on the islands.

Monday...moderate confidence. MVFR/IFR possible early...then
improving to VFR. Northwest wind gusts to 30 knots developing in the
afternoon.

Tuesday...high confidence. Mainly VFR.

Tuesday night into Wednesday...conditions lowering to IFR with snow
changing to ice then rain...quickest along the coast.

&&

Marine...
forecaster confidence levels...

Low...less than 30 percent.
Moderate...30 to 60 percent.
High...greater than 60 percent.

Short term /through Saturday night/...high confidence.

High pressure builds over the waters from the west allowing winds
and seas to subside gradually. Seas remain above 5 feet on the
outer waters so am allowing the Small Craft Advisory to continue
on those waters through tonight.

Outlook...Sunday through Wednesday...high confidence.

Sunday...light winds and seas sun...then SW increasing to 10-20 knots
Sun night. Visibilities reduced in rain/snow Sun night.

Monday...increasing northwest winds develop with gale force gusts possible
in the afternoon and evening before diminishing overnight.

Tuesday...winds below Small Craft Advisory with subsiding seas as high pressure crests
over the waters.

Late Tuesday night into Wednesday...increasing SW winds with gusts to
Small Craft Advisory thresholds. Lowering visibilities in snow changing to rain.

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
Rhode Island...none.
Marine...Small Craft Advisory until 6 am EST Saturday for anz250-
254>256.

&&

$$
Synopsis...kjc/rlg
near term...kjc/rlg
short term...rlg
long term...kjc
aviation...kjc/rlg
marine...kjc/rlg

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