Scientific Forecaster Discussion
fxus61 kaly 242351
Area forecast discussion
National Weather Service Albany New York
751 PM EDT Tue Apr 24 2018
clouds thicken tonight with rain overspreading the region
after midnight, as low pressure slowly moves from the Carolinas
this evening to Cape Cod by Thursday morning. Periods of rain
continue Wednesday into Thursday, as the system only slowly
lifts north and east into eastern Canada.
Near term /until 6 am Wednesday morning/...
as of 751 PM, high clouds have overspread our region and clouds
will thicken through the night. Rain along the leading edge of
low level jet forcing and warm and moisture advection is timed
to begin in western and southern areas an hour or two after
midnight, and the rest of our region before daybreak.
There could be some quick drop to the temperatures in some
areas this evening before the clouds thicken. Temperatures could
also fall a few degrees toward wet bulb temperatures once the
rain begins. So, lows tonight in the 40s, with around 40
northern areas and near 50 southern areas.
Short term /6 am Wednesday morning through Friday/...
the upper energy and low level forcing will support widespread
rain much of the day. There could be a rumble of thunder in the
Mid Hudson valley and northwest CT but the zone of best instability
will likely track east and south of our region. With the clouds
and rain, highs Wednesday in the 50s, with lower 50s north and
upper 50s south.
Upper energy exits Wednesday night but a trailing northern
stream upper impulse approaches from the Great Lakes. Coverage
of rain decreases to showers through the night and low level
temperatures cool behind the cold front. There are some
disagreements in guidance/ensembles as to the track and strength
of the trailing upper impulse through or just north of our
region Thursday. Depending on the track, some lingering showers
Thursday with the upper cold pool, but may be confined to areas
north of the Mohawk Valley to southern Vermont. All other areas may
just see some Morning Sun then widespread clouds developing
when the convective temperature is reached, and a few sprinkles
possible. Highs Thursday in the lower to mid 60s but 50s in
Sources of guidance/ensembles having difficulty resolving
features in such a chaotic upper pattern into Friday. Previous
guidance/ensembles suggested dry weather Friday. Now there is
an increasing consensus for a trailing piece of upper energy
tracking out of the mid Atlantic U.S. That could bring
considerable clouds and showers into our region Friday.
Indicating clouds and just scattered showers Friday and will
leave flexibility for changes with future guidance and
forecasts. Highs Friday in the mid 50s to lower 60s.
Long term /Friday night through Tuesday/...
rain showers will be around for the beginning of the long term
period with a couple of disorganized pieces of energy traversing the
region. High pressure will build over the region providing
pleasant weather for the end of the weekend into early next week.
Friday night through Saturday...a shortwave trough over the
southeast Continental U.S. Will lift to the northeast providing marginal
dynamic forcing and widespread light rain showers late Friday
through Saturday. An additional piece of northern stream energy will
swing through the region later on Saturday keeping a chance for
light rain showers over the region into Saturday night. Low
temperatures Friday/Saturday night will be in the upper 30s to low
40s. Highs on Saturday will be in the low 50s to low 60s.
Sunday through Tuesday...upper tropospheric ridging and associated
surface high pressure will dominate our weather Sunday through
Tuesday. Large scale subsidence will provide partly cloudy to mostly
sunny conditions during this time period as well. The upper ridging
combined with west/southwest flow and a stronger sun angle will
raise tempertures into the low 60s on Monday and possibly into the
low 70s on Tuesday.
Aviation /00z Wednesday through Sunday/...
overnight, ceilings will continue to lower and light rain will
arrive from south to north after midnight. The steadiest and
heaviest rain will likely be around kpou/kpsf by late tonight,
where IFR conditions are expected. Elsewhere, flying conditions
will lower to MVFR for kalb/kgfl by the late night hours. South
to southeast winds will be around 5 to 10 kts this evening
with some gusts to 20kts at kalb. Winds diminish overnight to 5
to 10 kts and may start to become east to northeast by late
tonight in the Hudson Valley.
During the day on Wednesday, steady light rainfall and low
ceilings will continue through at least early afternoon. IFR
conditions are most likely for kpsf/kpou, although brief periods
of IFR cannot be totally ruled out at kalb/kgfl, although will
only go with MVFR for now due to uncertainty regarding IFR
extent/duration at those sites. East to northeast winds will be
5 to 10 kts through the day.
Wednesday night: high operational impact. Likely rain showers...ra.
Thursday: moderate operational impact. Breezy chance of rain showers.
Thursday night: no operational impact. No sig weather.
Friday: moderate operational impact. Chance of rain showers.
Friday night: moderate operational impact. Chance of rain showers.
Saturday: moderate operational impact. Chance of rain showers.
Saturday night: no operational impact. No sig weather.
Sunday: no operational impact. No sig weather.
clouds increase quickly this evening with rain overspreading
the region tonight ahead of a complex storm system approaching
from the south. Periods of rain continue Wednesday into
Thursday, as the system lifts slowly north and east of upstate
Rain and elevated relative humidity values are expected Wednesday. Relative humidity values
will be greater than 60 percent Thursday with lingering scattered
Winds will be east to southeast Wednesday at around 15 mph and
west at 15 to 25 mph Thursday
widespread hydrological problems are next expected the next
The next chance for widespread precipitation arrives tonight.
It is expected to fall mainly as rain. The rain will persist
through Wednesday into Thursday a complex storm system impacts
the Hydro service area. Total rainfall amounts tonight into
Thursday morning are expected in the three quarters of an inch
to inch and a half range with a few locally higher amounts.
The latest mmefs guidance shows minor rises on area rivers and
creeks at this time with the gefs most aggressive with a few
points reaching minor flooding dependent on snow melt with the
quantitative precipitation forecast. However, the gefs continue to over do the snow melt the
past several weeks. A few river points may touch action stage
late this week based on the nerfc forecasts depending on how
much snow melt and rainfall combine into run off into rivers.
Cooler temperatures will allow for flows to start to decrease
late in the week.
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.