Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

000 
FXUS61 KALY 291057
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
657 AM EDT Thu Jun 29 2017

.SYNOPSIS...
Clouds will thicken this morning, as a warm front approaches from 
the west. This warm front will bring some showers to to areas mainly 
north of Albany today. As the warm front pushes northeast across our 
area tonight, showers and thunderstorms are expected, some with 
heavy rainfall for northern parts of the area. Then, a very warm and 
humid air mass will be in place for Friday into the weekend, with 
additional showers and thunderstorms each day, especially in the 
afternoon and evening hours. Some of the storms could be strong to 
severe and produce heavy rainfall.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 630 AM EDT, Mid level clouds have thickened across the 
region early this morning, ahead of a warm front approaching 
from the Great Lakes. Dry conditions still occurring across the 
entire area at this hour, so have scaled back pops by a few
hours this morning. Dry air in low levels resulting in virga
initially. Showers moving to the eastern end of Lake Ontario and
will develop across the western Adirondacks over the next few
hours. The showers will move in as the warm front impinges, 
mainly across the Adirondacks, upper Hudson Valley and northern 
parts of southern VT this morning into the afternoon. Not really
seeing any instability noted in the models through the day, so 
will not mention any thunder yet. Temperatures will be cool 
where showers occur across northern areas, with mainly mid to 
upper 60s for highs, but from around I-90 and the Capital 
District southward, temps should reach the upper 70s to lower 
80s with some breaks of sunshine expected.

Additional showers and some thunderstorms will move in from the west 
this evening, again mainly for areas north of the Capital District, 
associated with the nose of a strengthening southwest flow aloft. 
Surface-based instability will be lacking, but models indicating 
elevated instability will be present so will mention chance of 
thunder. PWATs will start to surge as the surface warm front 
advances into our region, so will mention locally heavy rainfall 
north of the Capital District. There is a Marginal Risk of Severe 
storms north and west of Albany this evening, but it is questionable 
whether strong winds aloft would be able to mix to the ground due to 
a possible low-level inversion in place. Will mention the threat in 
the HWO, but this appears to be a limited/conditional threat based 
on a strengthening wind flow aloft, and uncertainty of mixing. It 
will be warmer and more humid tonight than recent nights, with lows 
in the 60s.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
On Friday, our area looks to be firmly entrenched in an increasingly 
warm and humid air mass, as the warm front lifts well north. The 
flow aloft will be southwesterly and neutral, although models have 
been hinting at a diffuse surface boundary lurking across the area. 
This boundary along with differential heating/terrain will trigger 
scattered to numerous showers and thunderstorms, especially during 
the afternoon and evening hours. Will mention highest pops west of 
the Hudson Valley, where the boundary looks to set up. There is a 
Slight Risk of severe thunderstorms for the western/southern 
Adirondacks due to increasing instability and moisture. Models 
showing a maximum of SBCAPE in this area around 1500-2000 J/Kg with 
0-6 km shear increasing to around 30 kt. Main threat looks to be 
damaging wind in the warm/moist air mass, although some large hail 
cannot be ruled out in the stronger updrafts since mid level lapse 
rates look marginal around 6 to 6.5 C/Km. Farther southeast across 
much of the rest of the area, the severe threat is more muddled due 
to slightly lower instability and weaker shear. Still, Gusty winds 
and locally heavy rainfall will be possible across much of the area. 
Temperatures will soar into the mid to upper 80s for most valley 
locations, with dewpoints increasing to around 65-70 making it feel 
quite muggy. 

Showers and thunderstorms could linger well into Friday evening, 
with an air mass supportive of maintaining convection with humid 
and relatively unstable conditions (for night time). Will mention 
gradually decreasing pops after midnight, with the severe threat 
also finally decreasing by the early morning hours.

Not much change in the air mass for Saturday, with perhaps a better 
chance for more widespread convection developing due to a better 
forcing. Models continue to indicate a pre-frontal trough moving 
into the region during the day on Saturday, which will lead to 
convective initiation. The degree of cloud cover is uncertain early 
in the day, although not much sunshine will be needed to allow for 
moderate levels of instability to build with the most/humid air mass 
in place. SBCAPE could reach as high as 1500-2500 J/Kg, with 0-6 km 
shear around 25-30 kt, which would be sufficient for organized 
storms. Again mid level lapse rates while not overly impressive, are 
forecast to be steeper than some recent events this season with a 
very warm and humid air mass in place around 6 to 6.5 C/Km. As of 
now, the entire area is in a Marginal Risk for severe storms, which 
seems reasonable for a Day 3 outlook. If confidence increases, then 
a greater threat may develop. Also, locally heavy rainfall will be 
possible again with some flooding of urban/poor drainage areas. It 
will be another warm and humid day, with temps and humidity levels 
similar to Friday.

Showers and thunderstorms could linger well into Saturday night 
(maybe even more so compared to Friday night), with a supportive air 
mass along with the surface boundary moving through. Strong to 
severe storms and heavy rainfall threat could persist through the 
evening, then decreasing after midnight.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
The extended forecast opens with a cold front moving across eastern 
NY and western New England.  There is pretty good agreement with the 
medium range guidance that this front will be making steady progress 
across the region in the late morning into the early afternoon. 
Instability is not expected to be large at this point, but SBCAPES 
could be around 500 J/kg with sfc dewpts still in the 60s for the 
better part of the region.  A chance of showers with a slight chance 
of thunderstorms was kept in the forecast with highs near normal 
with upper 70s to lower 80s in the valley areas and NW CT with a few 
mid-80s in the mid-Hudson Valley, and upper 60s to mid 70s over the 
mtns.  Sunday night some slightly drier air infiltrates the region 
with the weak cold advection in the wake of the front. Lows temps 
fall back into the mid 50s to mid 60s across the region.

Monday-Monday night...The frontal boundary may stall across PA and 
Nrn NJ. The long-wave trough will remain over southeast Canada and 
the Northeast.  A short-wave swinging through the upper-level trough 
may focus isolated to scattered showers across the region.  The day 
should not be a washout with high temps similar to Sunday with 
seasonal normals in the 70s to lower to mid 80s across most of the 
forecast area.  High pressure will be building in south of James Bay 
with fair, cool and dry conditions for the night time period with 
lows in the 50s to around 60F. 

Independence Day into Wednesday...The 00Z GFS and Canadian GGEM are 
mainly dry during this time frame with high pressure building in 
over the region.  The 00Z ECMWF has one more short-wave moving 
across the region Independence Day with a slight chance of showers 
and thunderstorms.  A superblend of the guidance was in favor of 
higher chance pops.  We kept the pops at slight chc at best in the 
gridded forecasts.  The WPC guidance favors the Canadian anticyclone 
building into southwestern Quebec by early WED with fair and dry 
weather continuing into the mid-week.  A frontal boundary remains 
stalled across PA and the Ohio Valley.  Some of the GEFS members 
have low pressure moving along the boundary Independence Day to WED 
with a slight chc of showers.  We kept the pops at slight chc in the 
grids, but again this day may likely end of dry. The 00Z ECMWF has 
high pressure settling right over the forecast area on WED.  Highs 
will generally be in the upper 70s to lower 80s across the valleys, 
and upper 60s to mid 70s over the higher terrain,  and lows will be 
in the 50s to lower 60s. Humidity levels should be reasonable and 
not oppressive for early July with sfc dewpts in the 50s to lower 
60s.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
High pressure continues to move off the Mid Atlantic Coast this
morning, as a warm front continues to approach from the lower
Great Lakes Region and the Ohio Valley. The warm front will
focus some showers and isolated to scattered thunderstorms late
this afternoon into this evening.

VFR conditions are expected until about 22Z for 
KGFL/KALB/KPSF/KPOU with increasing mid and high clouds through 
the late morning hours and into the early afternoon. Some 
showers may move into KGFL 16Z-18Z with VFR vsbys and cigs in 
the 5-6 kft AGL range. Some showers and possibly isolated to 
scattered thunderstorms may reached KALB/KPSF btwn 23Z/THU- 
00Z/FRI. PROB30 groups were used from 00Z-04Z for these two 
sites, as well as KGFL. MVFR conditions will be possible with
the showers and thunderstorms.  KPOU will likely continue VFR 
into Thursday evening with mid-level cigs around 10 kft AGL.

Some MVFR mist may form at all the TAF sites well after 06Z as
we enter a moist and humid air mass.

The winds will increase from the south at 7-13 KTS with some 
gusts in 18-22 KT range at KALB/KPSF in the late morning and 
through the afternoon. The winds will decrease tonight from the
south to southwest to 5-10 KT. 

Outlook...

Thursday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Friday: Moderate Operational Impact. Chance of SHRA...TSRA.
Friday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Saturday: High Operational Impact. Likely SHRA...TSRA.
Saturday Night: High Operational Impact. Likely SHRA...TSRA.
Sunday: Moderate Operational Impact. Chance of SHRA...TSRA.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: Low Operational Impact. Slight Chance of SHRA.

&&

.FIRE WEATHER...
Clouds will thicken this morning, as a warm front approaches from 
the west. This warm front will bring some showers to to areas mainly 
north of Albany today. As the warm front pushes northeast across our 
area tonight, showers and thunderstorms are expected, some with 
heavy rainfall for northern parts of the area. Then, a very warm and 
humid air mass will be in place for Friday into the weekend, with 
additional showers and thunderstorms each day, especially in the 
afternoon and evening hours. Some of the storms could be strong to 
severe and produce heavy rainfall.

Minimum relative humidity values today will range from around 45 
percent across the southern part of the area to 65 percent north. RH 
will increase to maximum values of 90 to 100 percent tonight. 
Minimum RH values on Friday will range from around 50 percent across 
the southern part of the area to 70 percent north.

Winds today will be southerly around 10 to 15 mph. Winds will remain 
southerly tonight at 5 to 15 mph. Winds on Friday will shift to the 
southwest around 10 to 15 mph.

&&

.HYDROLOGY...
Showers are expected today, mainly for areas north of I-90 and the 
Capital District, ahead of a warm front approaching from the west. 

As this front moves through the area this evening and tonight, 
showers and thunderstorms may produce locally heavy rainfall for the 
western Mohawk Valley, Adirondacks and Lake George and Glens Falls 
area. This rainfall may cause minor flooding of urban, low lying and 
poor drainage areas. 

Additional showers and thunderstorms are possible Friday and 
Saturday as well, especially during the afternoon and evening hours. 
With a warm and humid air mass in place, any thunderstorm will be 
capable of producing locally heavy rainfall once again. Some showers 
or t-storms may be possible on Sunday as well, although the cold 
front will be pushing through. It looks like mainly drier weather 
will build in for early next week, although a few showers cannot be 
ruled out.

By the end of the weekend, the heaviest rainfall looks to be across 
areas north and west of Albany, where basin average amounts look to 
be at least one to two inches of rainfall, with less rainfall south 
and east. However, thunderstorms may result in locally higher totals 
in some spots throughout the HSA.

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...Frugis/JPV
NEAR TERM...JPV
SHORT TERM...JPV

National Weather Service Glossary of Abbreviations