Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Albany New York
734 PM EDT sun Jul 24 2016

Synopsis...
hot temperatures, increasing humidity and chances for showers and
thunderstorms return for Monday as a frontal boundary approaches
from the west. More dry weather is expected from Tuesday through
the middle of the week as high pressure builds back in across the
region.

&&

Near term /until 6 am Monday morning/...
as of 730 PM EDT, convection in the Great Lakes and Ohio Valley
is spilling more high/mid clouds into western New York/PA and is
building east. Upper and low level ridge axis building east of our
region. So, intervals of mid and high clouds will occur much of
the night over our entire region. Light winds will become light
south to southwest toward daybreak.

There are quite a few different possibilities as to the evolution
and track of convection that develops in the Ohio Valley later this
afternoon and evening. Various mesoscale models have different
solutions, some showing a weakened small cluster of showers and
isolated thunderstorms along the advancing dew point boundary
around daybreak across the eastern Catskills and Mid Hudson
valley. Other guidance shows the small cluster tracking well south
of the Mid Hudson valley. Other guidance shows most of all the
showers and storms dissipating along the dew point boundary
through the night, but new strong convection rapidly developing
over eastern New York and western New England around mid morning Monday.

The one constant is the dew point boundary with increasing dew
points building in from the west but the Mode and coverage of any
weakening showers and thunderstorms is very much in question.
Boundary layer flow will slowly increase from the west and
southwest, which is downslope, and there is very little upper
dynamics or upper jet support for convection in our region. So,
acknowledging isolated to scattered showers and thunderstorms
toward daybreak into the western Mohawk Valley, eastern Catskills,
Mid Hudson valley and into northwest CT. This may be updated once showers
and storms can be tracked through tonight. Low temperatures with
the increasing cloud cover and increasing dew points in the 60s to
near 70...but around 60 northern areas and parts of southern Vermont.

&&

Short term /6 am Monday morning through Wednesday/...
guidance again not in full agreement on coverage, timing and
intensity of convection tomorrow. Upper dynamics, upper jet
structure and low level forcing will be relatively weak through
the day but rapidly increasing low level moisture will contribute
to increasing instability. West to southwest boundary layer flow
will be downslope...suggesting scattered coverage, not necessarily
likely. The amount of mixed mid and high clouds will determine
high temperatures but as long as new convection initiates more in
the afternoon, intervals of breaks and thinning of mid and high
clouds should still allow for highs well into the 80s to lower
90s. Heat indices may approach 100 in the Mid Hudson valley and northwest
CT but not quite. So, will include in hwo, highlighting the chance
that a heat advisory may need to be issued later.

The instability, convective available potential energy may be solidly over 1000 j/kg in many areas
Monday afternoon, along with some hints at some degree of
steepening of midlevel lapse rates, suggests that even with the
scattered nature of the storms tomorrow afternoon, some could
become severe. Our region is in a marginal to slight risk in the
severe weather outlook from spc, with damaging winds the primary
threat but some hail could occur as well.

The better low level forcing along the advancing low level thermal
and moisture boundary and westerly wind shift looks to be during
the evening and overnight Monday night when some diurnal cooling
should be occurring but keeping potential severe in the forecast
through Monday evening. Some low level drying and partial clearing
could occur before daybreak with lows in the 60s.

Continued drying Tuesday with considerable sunshine and breezy
west to northwest winds. Highs Tuesday in the 80s to near 90.
Similar weather Wednesday but less wind with highs again in the
80s to around 90.

&&

Long term /Wednesday night through Sunday/...
this will be a stagnant period of little atmospheric motion to
get things moving. As such...our region will be more or less stuck
between two frontal boundaries north and south. Waves will ripple
along these boundaries...and showers and thunderstorm will be
possible each day...particularly approaching and during the
weekend.

After high temperatures from around 80 degrees in the mountains to
the lower 90s down the Hudson Valley on Thursday...showers and an
overall increase in cloud cover will keep daily highs in the around
70 degree...to lower or mid 80s range for the balance of the period.
Overnight lows will be in the upper 50s to upper 60s range for the
entire period. Daytime highs at Albany are in the lower 80s...with
overnight lows in the lower 60s.

&&

Aviation /00z Monday through Friday/...
a warm front will approach from the southwest Monday morning, and
lift northeast of the region by midday. A cold front will then
approach from the west late Monday afternoon and evening.

For most of the overnight hours, mid level clouds will increase.
Some showers/thunderstorms currently across central PA may
approach kpou toward daybreak. Otherwise, mainly VFR conditions
are expected through daybreak.

As the warm front moves across Monday morning, isolated to
scattered showers/thunderstorms will be possible at the taf sites.
Have included a vcsh mention at this time to account for this.

Additional isolated to scattered showers/thunderstorms may
develop along and ahead of the cold front later Monday afternoon.
Will include a prob30 group for this possibility.

Outside of any showers/thunderstorms, mainly VFR conditions are
expected. Localized MVFR/IFR conditions will be possible within
any showers/thunderstorms.

Winds will become light/variable overnight, then shift into the
south to southwest Monday morning at 5-10 knots. By Monday afternoon,
southwest winds may increase and become gusty at times, perhaps up
to 20-25 knots in some areas.

Winds will be much stronger, and variable in direction in and near
any thunderstorms.

Outlook...

Monday night: moderate operational impact. Scattered rain showers...tsra.
Tuesday: no operational impact. No sig weather.
Tuesday night: no operational impact. No sig weather.
Wednesday: no operational impact. No sig weather.
Wednesday night: no operational impact. No sig weather.
Thursday: moderate operational impact. Slight chance of rain showers...tsra.
Thursday night: moderate operational impact. Chance of rain showers...tsra.
Friday: moderate operational impact. Chance of rain showers...tsra.

&&

Fire weather...
hot temperatures, increasing humidity and chances for showers and
thunderstorms return for Monday as a frontal boundary approaches
from the west. More dry weather is expected from Tuesday through
the middle of the week as high pressure builds back in across the
region.

Relative humidity values will range between 75 and 100 percent
tonight and Monday night. Relative humidity values will drop to
around 50 to 65 Monday afternoon and to around 40 to 55 percent
Tuesday afternoon.

Scattered thunderstorms are expected Monday and Monday night.

Winds will becoming variable around 5 kt or less tonight. Winds
on Monday will become southwest at 15 mph or less. Winds shift to
west and northwest at 15 mph or less Monday night, then increase
to around 15 mph with possible gusts to 25 mph Tuesday.

&&

Hydrology...
dry weather will occur through tonight. However, the next frontal
boundary will approach for Monday bringing additional chances for
showers and thunderstorms. Locally heavy rainfall will be possible
with any persistent storms but basin wide amounts should be a
half inch or less.

Dry conditions return for Tuesday and Wednesday as high pressure
builds back into the region.

Flows continue to be well below normal for mid to late July at
many locations in the Hydro service area, especially our western
New England counties.

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...none.
Massachusetts...none.
Vermont...none.

&&

$$
Synopsis...NAS
near term...kl/NAS
short term...NAS
long term...elh
aviation...kl/bgm
fire weather...NAS
hydrology...NAS

National Weather Service Glossary of Abbreviations