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fxus61 kaly 211043 
afdaly

Area forecast discussion
National Weather Service Albany New York
643 am EDT Mon Oct 21 2019

Synopsis...
foggy conditions early this morning especially in valley
locations then becoming mostly sunny. Milder with seasonable
temperatures. Another widespread soaking rainfall is expected
Tuesday night as a front moves across the region.

&&

Near term /until 6 PM this evening/...
foggy start to the day with dense fog occurring mainly in the
valley locations. A dense fog advisory is in effect until 9am
for most the forecast area, only the southern Adirondacks and
northwestern Connecticut are not in the advisory. The ground
was wet from the light rain Sunday and the winds very light to
calm so as skies cleared last night widespread fog and stratus
formed.

The region is squeezed between the departing remnants of Nestor
off the coast and an approaching system moving into the Great
Lakes. We have ridging across the region aloft and at the
surface so flow is very weak across the area. This along with
the late October sun the fog and stratus will not be so quick
to lift and burn off this morning. Do expected skies to becoming
mostly sunny. It will also be milder than Sunday with
seasonable highs in the lower 50s to lower 60s. A light easterly
flow will develop during the day.

&&

Short term /6 PM this evening through Wednesday night/...
the upper ridge will sharpen as it shifts off the coast
tonight as the stacked system over the plains deepens and
gradually moves to the western Great Lakes region. At the
surface, guidance indicates the ridge stubbornly holds on.
Clouds are expected to be in the increase after midnight so
widespread fog is not expected. Southeasterly flow will
increase across the higher terrain of western New England and
across the western Adirondacks.

Did have to slow the onset of the steady rainfall across the
area Tuesday. It's expected to begin by late in day west of the
Hudson River valley spreading eastward through the early
evening. However, some light showers are possible during the
afternoon as the atmosphere moistens up with the increasing
southeasterly flow. Guidance indicates the southerly low level
jet associated with the system is not going to be as strong as
previously expected. Do expect wind gusts in the 20s to about
30 mph across the higher terrain of western New England and
across the western Adirondacks during the day Tuesday.

The fronts associated with the system race eastward away from
the low and will occluded as they approach the area during the
day and move across the area at night. The bulk of the rain is
expected during the evening hours with it tapering off late at
night/very early Wednesday morning. Expecting about 0.50 to
1.25 inches across the area with the heaviest amounts across the
southern Adirondacks and Mohawk Valley. There could be issues
with ponding of water in roadways especially where leaves clog
drains.

The system will gradually move northward across Ontario Canada
Wednesday and Wednesday night. Conditions will improve
Wednesday especially during the afternoon as high pressure
located over the southeastern United States extends northward
into the region. A westerly flow will usher drier air in.

Mainly seasonable temperatures are expected.

&&

Long term /Thursday through Sunday/...
there remains large differences in model solutions heading into
the long term so the forecast details regarding timing,
placement and intensity of upcoming systems remains low
confidence.

We start the long term off on Thursday with our region caught in
between high pressure building into the mid-Atlantic to our
south and a active long wave trough over eastern Canada. As a
result of this pattern, southwest flow should ensue as a weak
850mb warm front moves into and stalls over eastern New York/western
New England. Uncertainty remains on exactly how far north the
boundary reaches which will be impact our daytime high
temperatures. Most of the members of guidance suggest the front
gets hung up near I-90 which is why we show upper 50s and low
60s south of I-90 but mid-upper 50s for areas north. A shortwave
looks to rotate around the base of the aforementioned longwave
trough passing through the Great Lakes/Ontario on Thursday. The
baroclinc zone in place plus sufficient forcing for ascent from
the shortwave could allow an area of showers to brush the
southern Adirondacks. We included chance pops in this region for
Thursday but kept other areas dry.

The baroclinc zone lingers over our region into Friday and guidance
suggests a stronger shortwave rotates around the base of the
longwave trough, digging into the Great Lakes and intensifying
as it shifts into northeast. As it does, it looks to steer
moisture from a cut-off low in the Southern Plains
northeastward. Stronger heights falls are modeled with the
approaching shortwave, especially as it heads towards New
England, and with the stalled boundary and redistributed 700mb
moisture, showers may develop over our area. There are still
plenty of the model difference on the intensity, timing and
areal coverage of the precipitation and it should be noted that
some members of guidance suggest the majority of the
precipitation develops over New England due to timing of the
shortwave and placement of the stalled boundary. But for now we
felt confident enough to place widespread chance pops at this
time for Friday.

The stalled boundary finally exits as a cold front early Saturday
morning with northwest flow ushering in a cooler Canadian air
mass into the region. Depending on when showers Friday night
exit, some showers may mix with snow in the elevations above
2kft in the Adirondacks. High pressure from the Ohio Valley
building eastward could lead to a tight enough pressure gradient
over our area that winds turn a bit breezy for Saturday. In
addition, the cooler air mass characterized by 850mb isotherms
ranging between -2c and -4c moving over the warm lakes could
keeps around on Saturday with some lake enhanced showers
reaching the southern Adirondacks. Temperatures on Saturday
should be cool given these circumstances with highs remaining in
the 40s in the hill towns and terrain while inching in the low
to mid 50s in the valley.

Upper level ridging and surface high pressure should build in
Saturday night and Sunday giving US a dry forecast. However, the
cooler air mass looks to remain in place. Thus, temperatures
should remain seasonably cool with lows Saturday night fall into
the low to mid 30s and daytime highs climbing a few degrees
higher than Saturday. Heading into Sunday night and Monday, we
chose to follow the previous forecaster and side with the European model (ecmwf)
and CMC-New Hampshire which both suggest that the broad riding over the
eastern Continental U.S. Steers the aforementioned shortwave that was in
the Southern Plains towards northeast. The GFS shows broad
ridging dominating but this seems to be the outlier and recent
events have favor the European model (ecmwf) solutions. Thus, we increase pops to
chance Sunday night - Monday for the entire region.

&&

Aviation /12z Monday through Friday/...
dense fog and LIFR visibilities will remain in place at
alb and gfl through 12z while fog at pou and psf is not
quite as dense but still leading to IFR visibilities. As
we near sunrise, a period of dense fog could develop at psf and
pou and we included a tempo group for LIFR visibilities mainly
between 09z and 13z.

While dense fog at gfl and alb should improve by 13z to IFR
visibilities, it looks like the fog should lift into a
stratocumulus deck leading to MVFR ceilings. Conditions
should gradually improve through the morning with all taf
sites likely returning to VFR conditions by 17z/18z.

Winds forecast to be light and variable through the taf period
ending 06z/22.

Outlook...
Tuesday...moderate operational impact. Chance of rain showers.
Tuesday night: high operational impact. Definite rain showers.
Wednesday: low operational impact. Breezy.
Wednesday night: no operational impact. No sig weather.
Thursday: no operational impact. No sig weather.
Thursday night: low operational impact. No sig weather.
Friday: moderate operational impact. Chance of rain showers.

&&

Fire weather...
foggy conditions early this morning especially in valley
locations then becoming mostly sunny. Milder with seasonable
temperatures. Another widespread soaking rainfall is expected
Tuesday night as a front moves across the region.

&&

Hydrology...
river levels continue to recede from last week's heavy rainfall.
Smaller rivers and streams are likely back to normal base flow,
although some of the larger rivers continue to slowly fall.
However, many of the larger lakes and reservoirs remain
elevated.

Another widespread rainfall is expected Tuesday afternoon and
night as a front moves across the region. The bulk of the
rainfall is expected to occur during the evening. Still
expecting about 0.50 to 1.25 inches across the area with the
heaviest amounts across the southern Adirondacks and Mohawk
Valley. Rivers and streams will to rise once again, however at
this time flooding is not expected. There could be issues with
ponding of water in roadways especially where leaves clog
drains.

Mainly fair weather returns for Wednesday and Thursday,
allowing river and stream levels to recede. Another frontal
boundary is expected to bring some more showers to the area on
Friday.

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.
New York...dense fog advisory until 9 am EDT this morning for nyz038>041-
043-047>054-058>061-063>066-082>084.
Massachusetts...dense fog advisory until 9 am EDT this morning for maz001-025.
Vermont...dense fog advisory until 9 am EDT this morning for vtz013>015.

&&

$$
Synopsis...iaa
near term...iaa

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