Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 231140
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
640 AM EST Fri Feb 23 2018

.SYNOPSIS...
Dry weather will start today before a warm front lifts north later
this morning. This will bring a round of milder temperatures and
rain today. Above normal temperatures will then continue through the
weekend...with yet another storm system bringing another round of
widespread rain and windy conditions Saturday night and Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Surface high pressure is centered over Maine this morning. It
continues to provide western and central NY with quiet and dry
weather but is also trapping widespread lower clouds across much of
the region. Further west, Low pressure is consolidating near Lake
Michigan where it is expected to lift north of the Great Lakes
through today while a warm front pushes north across the Ohio
Valley. Radar mosaic shows rain oriented ahead of this warm front
lifting across the southern half of Ohio toward western PA.

Latest models continue to indicate the warm front will shift the
leading edge of rain into the Southern Tier this morning most likely
by 8-9am. Temperatures in the western Southern Tier are largely just
above freezing so while there is a slight chance of some pockets
where freezing rain could occur the overall p-type is expected to be
plain rain. The shield of rain will expand across western and
central NY as the warm front lifts north across our region through
midday. This evening rain will taper to a chance of some lingering
rain showers behind a cold front. Total QPF ranges from 0.15-0.25
inches for most but could run above 0.25 inches with upsloping on
the Tug Hill.

A Winter Weather Advisory has been issued for freezing rain expected
to accumulate a few hundredths of an inch of ice on the Tug Hill
before temps warm above freezing. Oswego and Lewis counties have
been included until 4pm where temps even at this higher elevation
should warm above freezing.

Warm air advection behind the front will boost 850mb temps to +8C
which will help our high temps to climb into the mid 40s to lower
50s. Mesoscale guidance indicates that dewpoints pushing into the
upper 30s and 40s will support some fog mainly over the lake ice on
Erie and Ontario this evening. Winds veering to westerly behind the
passing front this evening looks to advect some fog east of the
lakes which could be down to a half mile or lower. Have placed
patchy fog in the forecast for now but may need to be changed to
areas of fog. While an outside shot at this point, a dense fog
headline may need to be issued if visibility drops below a quarter
mile.

Tonight, There will be some lingering upslope rain/showers mainly
east of Lake Ontario before midnight. After this time, dry weather
will prevail with some fog lingering over/east of the lakes much of
the night. Temps will slip back into the low to mid 30s.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
On Saturday there will be a ridge of high pressure across southern
Ontario/Quebec with a stalled frontal boundary well to our south. A
wave is forecast to develop along this boundary with the northern
fringe of warm air advection nudging into southern portions of the
cwa. 00Z model QPF consensus has trended slightly north with light
rain likely across the Southern Tier, then rapidly diminishing
chances to the north. Despite being on the `cold` side of the
boundary, temperatures will remain above normal with highs in the
lower 40s.

Low pressure developing near Wisconsin Saturday night is forecast to
strengthen to around 980mb as it tracks across Lake Superior and
into Ontario province on Sunday. Model guidance is in good agreement
on the large scale features considering the time frame. A cold or
occluded front from this system will cross the region on Sunday.

This system will bring a period of rain to all areas, with a 60-70
kt southerly 850 mb flow providing moisture and warmer air which
will increase the potential for elevated convection. There may even
be some thunderstorms, along with a half an inch to an inch of rain.
For the most part, this will not be enough to cause flooding,
however with more rain to our south on Saturday there is a risk the
Allegheny River will approach flood stage since its basin extends
into Pennsylvania.

This system will also bring a period of gusty winds on Sunday which
may reach high wind warning criteria. The greatest risk for strong
winds is across the Niagara Frontier and nearby lake plains. The
track of the low is a bit north of an ideal track, however skies are
likely to clear out Sunday afternoon when strong winds aloft
associated with this system will still be in place. While these
winds will be weaker than those found ahead of front, forecast
soundings suggest a three hour window mid day Sunday when strong
subsidence and lapse rates exceeding 8 deg c/km that should allow
most of this wind to mix to the surface. Uncertainty stems from how
strong winds aloft will be with model guidance differing on how
strong the low will be at this time. There may be downslope winds NW
of the Chautauqua Ridge late Saturday night. These winds often do
not mix to the surface while its raining, but the potential is
there. Based on all these factors, will expand the high wind watch
to include all of the lake plains northeast of Lake Erie, extending
to Monroe county. Wind gusts of 50 to 60 mph are possible in the
watch area.

Mixed precipitation or just freezing rain is a concern for the St
Lawrence Valley overnight with at least initially a supply of
subfreezing air from downstream on a NE flow sneaking in under the
warmer air aloft, but this should change over to rain by Sunday
morning. This may result in some icing in portions of Lewis and
Jefferson counties.

Finally of note will be temperatures, which should briefly spike
into the 50s across WNY. However, unlike the recent warmup, there
will likely only be a tiny window between the ending rain and
imminent winds for one to enjoy the spring conditions.

Sunday night and Monday will be uneventful in comparison, with high
pressure building across the region. This will result in dry weather
with highs in the 40s on Monday.

&&

.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
High pressure will drift across the region through mid-week with
temperatures running above climo(+5F - +10F), with daily highs in
the 40s and nighttime lows in the upper 20s to low 30s.
Precipitation chances will increase into Thursday as a wave ejects
from the Four Corners region to the Great Lakes.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
Mix of VFR/MVFR cigs south of Lake Ontario near 12z with a
southeasterly flow across our region. KART and KROC are reading VFR.
Later this morning, a warm front will lift northward into the
western Southern Tier while spreading widespread rain from southwest
to northeast. Expect cigs to prevail MVFR with winds veering from
the south. Some freezing rain is expected on the Tug Hill south of
KART.

There is a possibility of some patchy LLWS this afternoon/evening
with a 40-50 kt low level jet shifting over our region. Rain will
taper off west to east this evening with a cold front shifting east.
All precip should be finished by midnight at the latest. Low
MVFR/IFR cigs will linger through tonight. There is also some fog
expected to develop over the lakes behind the warm front. West winds
look to shift some of this fog over KBUF/KIAG/KART this evening with
VIS down to IFR.

Finally...since the KJHW observation has not been reporting (or
reporting very inconsistently)...we have continued with a rarely
used NIL TAF for KJHW. Safety concerns have played a major role in
this decision...especially given the continued potential for
low/erratic ceilings at this particular site.

Outlook...

Saturday...VFR/MVFR with additional periods of rain developing...
which may be mixed with a little snow or freezing rain across the
North Country at the onset. LLWS also becoming likely.
Sunday...Rain ending with improvement to VFR...though also turning
rather windy.
Monday...Mainly VFR.
Tuesday...Mainly VFR...with a chance of rain/snow showers across
the North Country.

&&

.MARINE...
Moderate southeasterlies across the Eastern Lakes Region this
morning with high pressure over Maine. Winds and waves expected to
remain below advisory levels through this morning.

Through today, winds will veer further to southerly and increase
toward 20kts on the eastern end of Lake Ontario as low pressure
passes by to our northwest. The offshore orientation will keep the
highest waves confined to Canadian waters.

In the wake of this system...high pressure will briefly build back
across the Lower Great Lakes on Saturday... before a strong area of
low pressure tracks northeastward across the Great Lakes on Sunday.
This latter system should bring at least a round of higher end
advisory-worthy conditions...with gale force winds possible.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory from 10 AM this morning to 4 PM EST
     this afternoon for NYZ006-008.
     High Wind Watch from Sunday morning through Sunday afternoon
     for NYZ001>003-010>012-085.
     High Wind Watch from late Saturday night through Sunday
     afternoon for NYZ019.
MARINE...None.

&&

$$

SYNOPSIS...JJR/SMITH
NEAR TERM...SMITH
SHORT TERM...APFFEL
LONG TERM...CHURCH
AVIATION...SMITH
MARINE...JJR/SMITH


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