Albany Office Forecast Discussion

000
FXUS61 KALY 011806
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
206 PM EDT Thu Oct 1 2020

.SYNOPSIS...
Expect a seasonably warm day under mostly to partly sunny skies
as a few lake effect rain showers shift into the southern
Adirondacks and Mohawk Valley this afternoon. A low pressure
system will lead to a period of light rainfall tomorrow morning
before we dry out in the afternoon. It will be mostly dry and
cool for the upcoming weekend, outside of an isolated shower
north and west of the Capital District.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 1:30pm...As thought in the previous discussion,
temperatures are running ahead of the forecast which is likely
due to a combination of our rather deep boundary layer mixing
up to ~800mb and southwesterly flow downsloping off the terrain.
Based on ASOS, NYS mesonet and backyard weather station
temperatures trends, we raised our high temperatures a few
degrees even more to show highs now reaching into the low to mid
70s in the Hudson Valley areas. The southern Adirondacks will
still be the cool spots due to lake effect rain showers and
clouds. GOES16 visible satellite shows most have already reached
their respective convective temperatures resulting in mostly to
partly sunny skies.

Lake effect rain showers off of Lake Ontario are actually still
north of Herkimer and Hamilton County continue likely due to our
secondary cold front only now reaching the Lake Ontario shores.
Once this boundary reaches the southern Adirondacks, winds
should become westerly which should direct lake effect rain
showers off of both Lake Ontario and Erie into the southern
Adirondacks and western Mohawk Valley. We adjusted POPs to
better match current radar trends and the HRRR output which
seems to be handling the lake effect the best. Otherwise,
previous forecast remains on track.

As of 630 AM EDT...A broad, positively-tilted trough will
remain anchored just to our west during the day today. At the
surface, a weak cold front will push across the area and slow
down its forward progression as it reaches New England.

The main precipitation focus for today will be in the form of
lake-effect rain showers, mainly impacting far northern
portions of Herkimer and Hamilton counties. An initial southwesterly
flow will keep this band just to the north and west of Herkimer
County this morning. However, as the cold front pushes eastward
by midday, winds will become more west-southwesterly which will
cause lake effect rain showers to slowly drifting into the
southern Adirondacks. Most of the time, this band will stay
just to the north of NY Route 28. A brief shower associated with
the band of showers off Lake Erie may brush portions of the
western Mohawk Valley this afternoon. Otherwise, expect dry and
seasonable weather for the rest of the region with some
sunshine. High temperatures will range from the upper 50s in the
Adirondacks to the lower 70s in the mid- Hudson Valley.

Tonight, the flow becomes more southwesterly again shifting any
remaining lake-effect showers to our north and west. As a
shortwave rounds the base of the trough tonight, a weak area
of low pressure will form along the boundary first in the mid-
Atlantic and then track northward towards our area. Clouds will
increase after midnight with some light rain starting before
daybreak. Low temperatures will dip into the 40s across most
areas (with some upper 30s possible in the Adirondacks).

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Clouds and a steady, light rainfall is expected on Friday as
the surface low pressure system continues its northward track
through our area. With guidance remaining consistent with this
feature, pops were raised into the low-likely category. Most of
the rainfall will occur during the morning hours given the
system will be moving away during the afternoon. Precipitation
amounts will generally be on the order of 0.10 to 0.25 of an
inch. Once the rain departs, some breaks of sun will be possible
during the afternoon. How high temperatures get will be based
on how much afternoon sun is around. Farther west, a surface
low across the Great Lakes will produce a few more lake- effect
and lake- enhanced showers for areas north and west of the
Capital District. Highs Friday will be in the 50s to lower 60s.

During Friday night and Saturday, mainly dry weather will be in
store, outside of areas north and west of the Capital District,
as the lingering surface low near the Great Lakes and another
upper-level shortwave, may produce a few more showers. Lows
Friday night will be in the upper 30s to lower 40s with Highs
Saturday in the upper 40s to lower 60s.

A small area of high pressure will squeeze into the region for
Saturday night, leaving a dry, mostly clear night. This will
allow temperatures to dip into the 30s for most locations. Some
patchy frost will be possible across the Adirondacks.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
The extended forecast begins with tranquil weather to close the
weekend, but then the large scale pattern becomes more unsettled
early next week.

Sunday...High pressure will begin the day over NY and New England
and then will drift downstream.  Some clouds should increase during
the afternoon, as a full latitude mid and upper level trough will
be approaching from the mid MS River Valley.  A northern stream
short-wave may bring a few showers or sprinkles west of the Hudson
River Valley before sunset.  Mid and upper level southwesterly flow
will be over the region.  Temps should be seasonable or slightly
above normal based on the National Blend with highs in the lower to
mid 60s in the lower elevations and mainly 50s over the higher
terrain.

Sunday night through Monday Night...The medium range deterministic
guidance has come into slightly better agreement with a northern
stream short-wave remaining unphased from the southern stream one
for coastal cyclogenesis to occur too far south and east of NY and
New England Monday afternoon.  The 00Z GFS keeps an open wave
progressive upper level trough passage, while the 00Z CMC/GFS-
Parallel run has some mid and upper level deformation showers with
the southern stream short-wave brushing locations south and east of
the Capital Region. The 00Z ECMWF took a big shift well to the south
and east for potential phasing, but the differential vorticity
advection with the mid and upper level trough should bring scattered
showers to most of the forecast area on Monday. Some of the showers
could linger into Monday evening especially south and east of the
Hudson River Valley.  This system will continue to be monitored,
since if the phasing occurs further north a fairly decent coastal
low could impact NY and New England. Lows Sunday and Monday nights
will be in the mid/upper 30s to lower 40s over the mtns and lower to
mid 40s over the valleys. Highs on Monday will be in the 50s to
lower 60s.

Tue-Tue Night...The mid and upper level flow briefly goes zonal in
the wake of cyclone for Tuesday. High pressure builds in from the OH
valley which allow for temps to rise above normal. H850 temps rise
into the +6C to +8C range.  High temps may reach the lower to mid
60s below 1000 ft in elevation, and mid 50s to lower 60s at 1000 ft
or greater.  The mid and upper level flow shifts southwesterly TUE
night ahead of a strong upper level trough approaching from Upper
Midwest and Great Lakes Region. We continued a dry forecast with
lows Tue night into 40s.

Wednesday...A strong cold front and a northern stream short-wave
trough will allow heights to fall and the threat for showers to
increase for the mid week.  Some uncertainty exists if this short-
wave will dig equatorward Wed night for a secondary low to form near
northern NJ and Long Island to continue a threat for a period of
showers or rain. If the H500 circulation moves over northern NY
based on the 00Z ECMWF, then there could be a few snow showers over
the Adirondack Park.  Max temps still look above normal ahead of
this system with mid 50s to mid and upper 60s over the forecast
area.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
VFR conditions will prevail through the balance of the afternoon and
evening hours.  Next upstream disturbance will overspread the TAF
locations after midnight where VFR/MVFR flight conditions will
occur.  At this time, given the system will be rather weak and quick
timing, this should reduce the potential for IFR as we will leave
out with this forecast issuance.  Rain/showers should end from
southwest to northeast Friday morning with VFR conditions returning.

West-southwest winds of around 10kts with occasional gusts to near
20kts will persist this afternoon.  Those magnitudes quickly
decrease at sunset with light and variable winds overnight.  Winds
will gradually become westerly Friday morning at speeds 5-8 kts.

Outlook...

Friday Night: No Operational Impact. NO SIG WX.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: Moderate Operational Impact. Chance of SHRA.
Monday: Moderate Operational Impact. Chance of SHRA.
Monday Night: Moderate Operational Impact. Chance of SHRA.
Tuesday: No Operational Impact. NO SIG WX.

&&

.FIRE WEATHER...
An upper level disturbance will bring some clouds and lake
effect rain showers to areas to the north and west of the
Capital District today, otherwise fair weather is expected. A
low pressure system will bring a widespread, light rainfall to
the region on Friday.

RH values will lower to 45 to 60 percent this afternoon and
rebound to near 100 percent tonight. RH values will remain
elevated on Friday, only lowering to 60 to 75 percent. Wind will
be generally out of the west to southwest at 8-16 mph today,
then trend calm tonight. Wind will be light out of the west to
southwest at 5-10 mph on Friday.

&&

.HYDROLOGY...
Area rivers and streams are generally holding steady or slowly
falling following the widespread, heavy rainfall from Wednesday.
Only a few will continue to slowly rise, but none will reach
action stage.

A few lake-effect rain showers will bring light rainfall amounts
(generally under 0.10 of an inch) to portions of the southern
Adirondacks today. Dry weather is expected for the remainder of
the area.

A widespread, light rainfall is in store late tonight through
tomorrow. Rainfall amounts will generally be between 0.10 and
0.25 of an inch. Little if any river and lake response is
expected from this event.

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.

&&

.EQUIPMENT...
Upper air ground equipment issues has prevented ALY from releasing
a 12 UTC 30 September, 00 UTC 01 October and 12 UTC 01 October
weather balloon. Technicians continue to fix this issue and we
are hopeful that we will successfully release a 00 UTC 02
October weather balloon.

&&

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

&&

$$
SYNOPSIS...Rathbun/Speciale
NEAR TERM...Rathbun/Speciale
SHORT TERM...Rathbun
LONG TERM...Wasula
AVIATION...Wasula
FIRE WEATHER...Rathbun
HYDROLOGY...Rathbun
EQUIPMENT...

NWS ALY Office Area Forecast Discussion