Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Binghamton New York
1247 PM EDT Sat Apr 19 2014

Synopsis...
broad high pressure will shift from Ontario and Quebec
today...into New England Sunday. The influence of this high
pressure system will keep our weather dry this weekend and into
Monday. Near to slightly below normal temperatures today...will
moderate Sunday into the upper 50s to middle 60s...and even more so
Monday with highs in upper 60s to low 70s. Our next good chance of
rain will come Tuesday as a showery cold front passes.

&&

Near term /through Sunday/...
1 PM update...
1037mb high currently sitting over James Bay with ridge axis
extending down into central Great Lakes will build east tonight into
Quebec toward area of strongest pressure rises. As it does, winds will
become light out of the north and eventually decouple after 06z. Strong
inversion will set up around 1kft by morning with a 3-8f spread in temperatures
between ridges and deeper valleys.

Skies will be mostly clear tonight with just a few cirrus sneaking in overnight
from systems across the southeastern U.S and SW flow coming up through the Midwest.
Winds become srly after 12z Sunday as ridge builds east and ahead of next
system. This will result in 800 mb temperatures incrsg to between +1 (in the east)
and +5c (in The Finger lks). Thus, coolest maxes tomorrow will be across
western cats and warmest across The Finger lakes where high temperatures will range
from 5-8 degrees above normal.

&&

Short term /Sunday night through Tuesday night/...
350 am update...
model consensus continues to advertise a larger separation between
departing high pressure offshore Nova Scotia and low pressure
approaching from the western Great Lakes region Sunday night-
Monday. This will mean better radiational cooling Sunday night
/especially first half before some high clouds start to move
in/...followed by a period of return flow and warm air advection
Monday-Monday night. Have followed warmer trend of guidance with
highs upper 60s to low 70s Monday...after 30s to near 40 for lows
Sunday night.

Latest operational runs of GFS/ECMWF/Gem agree now on waiting
until after 12z to sweep cold frontal showers through the region.
The rain itself is a solid bet...it is just a matter of which time
of day will be the main rainfall. Went ahead with high likelihood
of showers Tuesday...and as the time nears we will be able to
better hem in which specific hours will be involved. Front will be
progressive and moisture influx will be limited enough...to which
we anticipate less than a half inch of rainfall out of this
system. Thus not expecting much impact other than dampening plans
for general outdoor activities. Thermal profiles also too stable
to support convection...so no lightning expected.

Rainfall development and then eventual cold air advection Tuesday will
hold temperatures back to upper 50s-middle 60s for highs...followed
by upper 30s-low 40s for lows Tuesday night with decreasing chances
for showers.

&&

Long term /Wednesday through Friday/...
350 am update...
behind surface front from Tuesday...strong upper trough digs into
western Great Lakes Tuesday night...then drops across our region
Wednesday with strong cold air advection. GFS-European model (ecmwf) runs both keep
it as an open wave as it swings through...before differing on its
evolution well offshore. 1000-500mb thicknesses get sub-540
decameters for a time...contributing to the coldest day of the
period with highs Wednesday in the middle 40s to low 50s. Still a
chance of showers as well with that upper wave passing through.

Dry late Wednesday through Thursday night with high pressure in
charge at surface...and ridging occurring aloft. Temperatures also
moderating...especially by Friday...but next wave may also be
approaching by then with an increasing chance of showers Friday-
Friday night. Timing of course will be sorted out better in coming
days.

&&

Aviation /18z Saturday through Thursday/...
cold front has reached into northeast Pennsylvania and will soon be
through kavp. Post frontal cloudiness has scattered out. A few patchy
MVFR ceilings were still present in the upslope regions of c New York. Cold
air advection will lead to favorable conditions for scattered-broken VFR
cumulus/SC to form late morning with insolation. However...with
such dry air above the projected mixed layer...these clouds should
clear out by early afternoon for most tafs. The exception will be
at krme where the temperatures aloft are cooler which will lead to
the clouds hanging on longer.

After clouds clear out later today...VFR conditions will last through
12z sun.

Expect northwest winds of 10 to 15 knots today with gusts at or above 20 knots.
Winds will become light northerly after sunset tonight.

Outlook...

Sun...VFR.

Sun night to Monday...VFR with local MVFR/IFR if fog develops.

Tue-Wed...showers with MVFR possible.

&&

Fire weather...
5 am Sat update...

For today minimum relative humidities are expected to drop to the
30s percent in Finger Lakes region of New York this afternoon.
Relative humidities will drop to the upper 20s to lower 30s percent
in the rest of central New York and northeast Pennsylvania this
afternoon. Winds will be from the northwest 10 to 15 miles per hour with some
gusts to 20 miles per hour at times. Fine fuels were running below 10
percent. This comes close to our red flag criteria in PA. In New York
the criteria is for wind gusts of 25 miles per hour or more. Biggest question
will be the wind gusts in NE PA and that is where the uncertainty lies
at this time. After collaboration with ctp and phi will issue an
Special Weather Statement to cover and day shift can coordinate with PA state partners
to see if red flag is warranted later this morning.

Fuels will be dry enough on Sunday and Monday but winds will be
under 20 miles per hour especially Sunday with the departing high. Afternoon min
relative humidity will be in the 20s Sunday and 30s Monday.

&&

Bgm watches/warnings/advisories...
PA...none.
New York...none.

&&

$$
Synopsis...djn/mdp
near term...pvn
short term...mdp
long term...mdp
aviation...djn
fire weather...