Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 182045
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
345 PM EST Mon Feb 18 2019

.SYNOPSIS...
Areas of light snow this afternoon will taper off
tonight. Seasonably cold weather will return tonight into Wednesday
with mainly dry weather. Another system will bring snow
transitioning to a wintry mix late Wednesday into Wednesday night,
with warmer air returning by Thursday.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
As of 300 pm, synoptically-driven light snowfall has fizzled
enough to cancel the remaining counties from the winter weather
advisory. CAMs are fairly consistent in showing light snow
redeveloping across portions of the eastern Mohawk Valley,
Capital District, and Helderbergs along the back side of the
ongoing precipitation shield from around 20-00Z in a narrow
band. We appear to be seeing the beginning of this occurring
presently. The wind field appears reminiscent of Mohawk- Hudson
Convergence conceptual models (per CSTAR research) with
northerly flow down the Hudson Valley converging with west-
northwesterly flow down the Mohawk Valley. This could allow for
additional light accumulations perhaps around an inch in a
fairly narrow band. PoPs were increased to likely in the
aforementioned area this evening, and a Special Weather
Statement was issued.

Cold advection tonight as the low continues to depart offshore
on west-northwesterly flow. This should allow temps to fall into
the single digits and teens, with some negative numbers over the
higher terrain north of I-90. Winds will remain elevated
overnight with the approaching surface high still to our west,
so the wind chill factor is expected to fall into the +/- single
digits, with some negative teens over the high terrain north of
I-90. Clouds should clear out as well, especially after
midnight.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
Seasonably cold period Tuesday into Wednesday as 1035+ mb high
expands into the region. Despite a good deal of sunshine
Tuesday, temperatures should remain several degrees below
seasonal normals, and a west-northwest wind around 5 to 15 kt
will make things feel brisk. Tuesday night, the high expands
overhead, which should make for good radiational cooling
conditions with the relatively fresh snow cover in place. Went
toward the colder side of the guidance envelope for lows. Clouds
will increase some late but may not be enough coverage to
impact lows.

Wednesday into Thursday, the focus will be on a deamplifying
midlevel trough moving from the Upper Midwest into southeast
Canada. Attendant primary surface low will remain well to our
west, with possible secondary low development off the southern
New England coast on Thursday. This is a pattern we have seen
often this winter. Isentropic lift will begin Wednesday
afternoon into the evening as the 850 mb winds increase to 40-50
kt out of the south-southwest. Thermal profiles appear cold
enough to support snow everywhere at the onset. Depending on the
timing, it could be working in during the end of the evening
rush hour, especially south and west of Albany. Warmer air aloft
will change p-type to sleet and freezing rain Wednesday night.
The departing high isn`t in an ideal position to keep cold air
locked in place, but it looks like at least light icing is
possible before temperatures rise late Wednesday night into
Thursday morning. Midlevel dry slot will be rapidly approaching
as well for late Wednesday night or Thursday morning, so we
could see steadier precip turn to drizzle and freezing drizzle.
Overall it does not look like a major event from a QPF
standpoint, and the timing does not look favorable for big
impacts, but it could be just messy enough for winter weather
headlines to be necessary with around 1-3 inches of snow/sleet
combined with up to a tenth of an inch of ice.

The system shifts east fairly quickly for Thursday as we
transition to isentropic downglide. It looks like a fairly mild
day as the boundary layer deepens during the late morning and
afternoon before cold advection can take hold. Highs in the
mid-30s to near 50 are expected with clearing skies.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Coming soon

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
Low pressure continues to move east of the Cape Cod this
afternoon. An upper level disturbance and a sfc trough will keep
periods of light snow going for most of the TAF sites into the
mid afternoon. The upper trough axis will move east of the
region tonight with high pressure building in from the Great
Lakes Region late tonight into tomorrow.

Widespread MVFR/IFR cigs and vsbys will continue at the TAF
sites until 18Z-20Z/MON with the snow. Conditions should
improve first at KPOU around 20Z with conditions increasing to
VFR levels with cigs around 4 kft AGL. KALB/KPSF may continue
with localized IFR vsbys/cigs, but mainly MVFR conditions until
the late afternoon into the early evening /21Z-00Z/ with a
localized convergent band of snow showers or snow near the
Capital Region and KALB/KPSF. KGFL should have the snow
diminish around 20Z, but MVFR cigs may linger until 01Z. Expect
cigs to linger in the high MVFR range at KALB/KPSF until 02Z-
03Z. Drier air will filter in with the subsidence in the wake of
the coastal low with conditions being in the VFR levels after
03Z/TUE at KPOU/KPSF/KALB/KGFL. Some cirrus maybe around early
tonight with the strong mid and upper level jet stream just
south of the region.

Expect mainly clear skies late tonight into tomorrow morning
with the sfc ridge building in, as VFR conditons will continue.

The winds will be from the north to northwest at 7-13 kts with
some gusts around 20-25 kts at KALB/KPSF. The winds will
decrease to 4-9 kts overnight, and then increase from the
northwest 8-12 kts after 14Z with a few gusts near 20 kts at
KPSF.

Outlook...

Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: Moderate Operational Impact. Chance of SN.
Wednesday Night: High Operational Impact. Likely SN...SLEET.
Thursday: Moderate Operational Impact. Chance of SHRA...RA.
Thursday Night: No Operational Impact. NO SIG WX.
Friday-Saturday: No Operational Impact. NO SIG WX.

&&

.HYDROLOGY...
Hydrological impacts are not expected through at least this
week.

Seasonably cold weather is expected through Wednesday, promoting
ice expansion on area waterways.

The next system arrives late Wednesday into Thursday morning
with snow transitioning to a wintry mix. Precipitation amounts
of generally a quarter to a half an inch are expected.
Temperatures are expected to run a bit above normal Thursday
into the weekend.

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
website.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.

&&

$$
SYNOPSIS...Thompson
NEAR TERM...Thompson
SHORT TERM...Thompson
LONG TERM...Speciale
AVIATION...Wasula
HYDROLOGY...Thompson


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