Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
939 PM EST Thursday Mar 5 2015
tonight will be another frigid night as temperatures drop towards
zero...and below zero inland and away from lingering lake effect
streamers. Shifting winds will take these weakening and Narrow Lake
effect snow streamers from south of Lake Ontario this evening to
east of Lake Ontario tomorrow. Temperatures will slowly moderate
through the weekend...and possibly rise to above normal by the
middle of next week.
Near term /through Friday/...
regional radars show lake effect snow showers slowly diminishing
off Lake Ontario this evening. This will continue as high pressure
will build across the lower Great Lakes...bringing with it a
drier air mass and lake induced equilibrium levels of less than
As an area of high pressure builds eastward across the lower
Great Lakes from the Midwest our surface winds will back to the
west-southwest and then diminish overnight. This shifting in the
wind will carry any remaining lake effect snow showers towards the
southeast end of Lake Ontario...meanwhile a dry air mass
associated with the area of high pressure over the Midwest will
aid in diminishing most of the cloud cover across the region.
The clearing in skies overnight will allow for temperatures to drop
to within a few degrees of zero. Record lows for Friday morning are:
buffalo: 0/2007, rochester: -9/2014, watertown:-21/2014. The winds
will diminish enough such that wind chill values will drop to around
-15f...but with both time and spatial coverage of sub -15f wind
chills (-20f north country) at a minimum will not issue any wind
chill advisories. "Warmest" overnight lows will be southeast of Lake
Ontario where lingering lake clouds will likely limit sub zero
The ridge axis of the surface high pressure will cross the region
Friday morning. A few clouds and possibly a flurry may remain
east of Lake Ontario before backing winds carry the moisture
northward towards southern Canada. Mostly sunny skies elsewhere in
the morning will have increasing amounts of clouds in the
afternoon behind the area of high pressure. Southwest winds will
be brisk through the afternoon ahead of the next storm system to
Short term /Friday night through Sunday/...
Friday night weak warm advection and some weak large scale ascent
from a middle level shortwave will bring thickening clouds from west to
east. Warm advection and deeper moisture will be maximized across
the north country where a few flurries or light snow showers are
possible. With the increase in cloud cover temperatures will not be
quite as cold as the previous night...with lows in the middle teens on
the lake plains with some single numbers in the coldest southern
tier valleys and Tug Hill region.
Later Saturday and Saturday evening a more notable middle level
shortwave and weak clipper low will move across the Great Lakes.
This will bring a better chance of some light snow to the entire
region as a period of deeper moisture...stronger large scale ascent
and convergence cross the region. Overall looks like just a light
accumulation with an inch or so in most areas...and possibly a few
inches east of both lakes with an added boost from upslope flow into
higher terrain and frictional convergence. Temperatures will make a
little more progress with the lake plains rising to around 30...with
middle to upper 20s across the higher terrain east of Lake Ontario.
Later Saturday night snow showers will diminish in the wake of this
system...although another weak middle level shortwave will cross the
area on Sunday and may produce a few more disorganized scattered
snow showers. Temperatures will be similar on Sunday with highs in
the lower 30s in most areas.
Long term /Sunday night through Thursday/...
Sunday night another in a series of shortwaves will cross the Great
Lakes and bring another chance of somewhat more organized snow
showers with some minor accumulations possible. These snow showers
will taper off from west to east on Monday as the middle level trough
exits into New England. Temperatures will begin a slow upward creep
on Monday with highs into the middle 30s across lower elevations.
The much anticipated warm-up for next week still looks to be on
target for at least Tuesday and Wednesday as the longwave pattern
briefly becomes more zonal across North America...with height rises
and warm advection spreading east across the nation. The latest GFS
and European model (ecmwf) have the warming arriving on Tuesday with highs into the
lower 40s in most areas. It still appears the warmth peaks Wednesday
with highs at least into the middle 40s...and possibly upper 40s across
the Genesee Valley and central New York. Both the GFS and European model (ecmwf) then bring
a broad trough into southeast Canada by Thursday with a cold front
pushing south into the region and bringing at least some cooling...
with more significant cooling by Friday.
The warm-up appears to be accompanied by an extended period of dry
weather from Tuesday through the end of the week with high pressure
over the Ohio Valley and lower lakes. A plume of deeper moisture and
rainfall across the southeast states will be kept at Bay through the
Despite the warmer temperatures...with no rain falling there will be
little or no flood risk initially. The warmer temperatures will
simply allow the snowpack to consolidate and ripen. While the depth
of snow on the ground will drop...only a small amount of water will
be released as the initial meltwater is re-absorbed by the remaining
snow. It is possible that temperatures may be warm enough for a long
enough period of time to increase the potential for ice breakup on
the streams and rivers...but without rain or significant runoff the
ice may very well stay largely in place despite a few warmer days.
Overall...expect this warm-up to ripen the snowpack...but a greater
flood potential will not be realized until the next warm-up when the
snow will be more ready to release its water.
Aviation /03z Friday through Tuesday/...
regional radars showing lake effect snow showers off Lake Ontario
slowly diminishing this evening. This will continue as high pressure
over the Midwest further builds east across the lower Great Lakes
overnight. However...a few of these lingering lake effect snow
showers may occasionally bring very localized and brief MVFR/IFR
visibilities to the kroc airfield. Overnight...winds will slowly back
around to west and southwest as high pressure from the Midwest
continues to push eastward. The combination of surface winds shifting to
the west-southwest and high pressure bringing in a much drier air
mass will help erode any lingering low cloud deck hanging over the
airfields. Expect VFR to prevail at all taf sites overnight and
through the remainder of the 00z taf cycle.
Friday night...mainly VFR with a chance of snow showers late.
Saturday...MVFR/IFR with snow showers becoming likely.
Sunday and Monday...mainly VFR with a chance of snow showers.
high pressure from the Midwest will continue to build eastward this
evening. Winds over the lakes will average less than 15 knots and as
the area of high pressure builds over the lower lakes tonight winds
will become light. Brisk southwest flow will develop on the lakes
tomorrow as the high shifts to the east ahead of another clipper
that will cross the eastern Great Lakes this weekend.