Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Albany New York
1238 PM EST Friday Mar 6 2015
Arctic high pressure will build east from the Great Plains and
reach the eastern Seaboard Saturday. From late Saturday into next
week a series of fast moving...moisture starved clipper low
pressure systems will move across the region with snow...flurries or
showers by midweek. Temperatures will moderate to near normals by
early in the week as the coldest air retreats well north into
Near term /through tonight/...
as of 1230 PM EST...mainly sunny skies and light winds continue
across the region. Temperatures have warmed into the 15-20 range within
most valley areas...and generally 10-15 above for most higher
elevations. Expect temperatures to rise an additional 2-4 degrees from
current levels in most areas...with Lower/Middle 20s in valleys
expected...and middle/upper teens across higher terrain.
These clouds will thicken at times overnight...as a fairly strong
upper level trough approaches from the upper Ohio Valley/lower
Great Lakes region. Despite this feature...low level moisture is
scarce...so only expecting high and middle level clouds to increase
this evening...before some lower clouds move into western areas
toward daybreak in association with strengthening low level warm
advection and added lake moisture.
It will not be as cold tonight...but will still be well below
normal. Temperatures are expected to drop into the single digits
in most areas.
Short term /Saturday through Monday night/...
during this period the 500hpa trough that has dominated eastern
North America since late January will flatten as the flow turns
west-northwest. Saturday and again Sunday short waves will cross the region in
this fast flow. The first will be accomp by a clipper low Sat
the second will drag an east-west cold front through the region sun
which will enhance lake effect response in west adrndks.
Both features will set up shsn and flurries...with some lake enhancement...but
both are rather moisture starved. Quantitative precipitation forecast totals for the entire period
are rather consistent in the model suite (gfs/ECMWF/NAM/gem) but
timing varies somewhat depending on lake impacts. Through Monday
morning totals are a few hundredths S & east of alb...and 0.10 t0
0.25 north & west with the greatest amounts over the west adrndks. The GFS
maintains a healthier lake response into the Tug Hill with
additional quantitative precipitation forecast on the order of another 0.10 or so Monday. With 15
to 1 ratios these could result in a few inches spread over the 2
days particularly north of i90.
Meanwhile during this period the core of the coldest Arctic air
will retreat well north into qb...as does the major hemispheric
500 hpa low. The fca will be on the periphery of the coldest air
and temperatures will trend slowly toward normals.
Long term /Tuesday through Thursday/...
this period will be mainly dry...as the 500hpa flow continues to
deamplify. Tuesday the fca is in between systems as the North Branch system
is well northwest of fca..and S branch passes just to our south. This
will result in a dry day west/pc conds and temperatures near or even a few
degree above normal.
Tuesday nt into Wednesday the GFS digs a much stronger 500hpa short WV
and a transient trough over NE and drops a stronger cold front southeast
through fca. The rest of the model suite (ecmwf/Gem/hpc) keep both
the fast flow...most of the 500hpa energy and coldest air with
this system well north of fca Wednesday. If it produces any precipitation it will be
light as it too remains moisture starved. For now will continue
to lean toward this solution.
Thursday into Friday the trough over the east passes well offshore as the
cold core retreats NE into qb and the North Atlantic. By the end of this
period 500hpa ridging is building into the east and along the
coast...and temperatures will continue to trend upward above normals into
the middle 30 to middle 40s.
Will populate efp with HPC grids as they are in the consensus of
Aviation /18z Friday through Wednesday/...
VFR conditions to prevail through the taf forecast cycle.
A weak wave aloft will approach and bring an increase in high and
some middle level clouds to the region tonight. Winds will generally
be light at speeds less than 10 kts.
A more impressive wave approaches later Saturday with thicker and
lower cloud coverage...however...precipitation associated with this
feature is not expected until after 18z Saturday.
Sat-Sat night: moderate operational impact. Chance shsn mainly in the
Sun-sun night: low operational impact. Slight chance shsn.
Mon: moderate operational impact. Chance shsn/shra.
Monday night-Wed: no operational impact. No sig weather.
no widespread Hydro problems are expected through the next 5 days.
Arctic air mass will dominate through Friday...with temperatures
remaining well below freezing. The Arctic air will retreat over
the weekend...but temperatures should still average below normal.
A moderating trend is then expected early next week with near normal
temperatures and above freezing daytime temperatures. Some snow will start
to melt...but will be on a diurnal cycle with temperatures falling back
below freezing at night.
For details on specific area rivers and lakes...including observed
and forecast river stages and lake elevations...please visit the
advanced hydrologic prediction service /ahps/ graphs on our