Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Albany New York
346 PM EDT Sat Aug 1 2015
a weak upper level disturbance will move across the
region tonight accompanied by some clouds and a passing shower. High
pressure will briefly build in from the Tennessee Valley and the Middle
Atlantic States overnight into Sunday with dry weather. A stronger
cold front will bring more scattered showers and thunderstorms for
Near term /through Sunday/...
as of 330pm EDT...somewhat organized convection along a dewpoint
boundary was sliding through Litchfield and Dutchess counties.
In-cloud and cloud to ground lightning was quite limited as echo
tops were rather low and sbcapes were around 1k j/kg or less.
Looking further upstream...water vapor loop continues to show a fast
approaching short wave where additional convection has developed.
As mentioned in previous discussions...this feature while
accompanied by very favorable middle level lapse rates /6-7
c/km/...the convection is diurnally driven and should diminish
with sunset. We will keep some probability of precipitation across the dacks where the
lapse rates are the steepest before sunset. Otherwise...minimal
activity for the remainder of the region. Skies should become
ptcloudy-moclear overnight as a narrow surface ridge and brief
height rises moves across the region. This should allow for winds
to decouple and become light and variable overnight. As dewpoints
were into the middle 50s and overnight lows in the middle to upper
50s...patchy fog may develop.
The aforementioned ridge slides east and the upper level synoptic
flow becomes more southerly. Should be a rather mild end to the
weekend as h850 temperatures climb back into the middle teens. Couple
that with increasing south-southwest winds will result in favorable
downsloping for valley temperatures to climb well into the 80s and
dewpoints remaining or slightly falling into the lower and middle
50s. Forecast bufr profiles suggest fairly deep mixing to commence
on Sunday as we have also increased wind magnitudes as gusts into
the lower 20kt range.
Short term /Sunday night through Monday night/...
Sunday night...southerly flow will remain in place and increase
aloft as upstream trough/short wave amplify the synoptic flow.
While it should remain dry across most of the region...isentropic
lift and moisture advecting into western and central New York may
develop an elevated shower/storm across the dacks and western
Mohawk Valley overnight. Lows will be milder than the previous
nights with u50s to m60s over the region.
Monday-Monday night...an active period of weather for the region
and model consensus favors a strengthening cold front impacting
the region with frontal passage to occur Monday evening. Severe parameters
look more favorable with the 12z guidance with bulk shear of
30-40kts...sbcapes 1-2k j/kg...showalter values of -2 to -4c and
middle level lapse rates of between 6-7 c/km. Low level hodographs
and channeling up the Hudson could prove to be interesting yet the
local/S look rather high at the present time /aob h850/.
Nevertheless...continued with the previous forecast with likely
probability of precipitation later Monday into Monday. Storm Prediction Center current outlook /which does not
update during the day shifts for swody3 and beyond/ remains
within a marginal risk as we will coordinate any future upgrades
to the outlook. Some locally heavy downpours will be possible too
as precipitable waters rise back to the 1.25-1.75 inch range. Highs will range
from the lower to u80s in the valley areas...and m70s to l80s over
the higher terrain. Lows Monday night will be in the m50s to m60s.
Long term /Tuesday through Saturday/...
a large trough across the northeast including closed low over Hudson
Bay....will continue to be the theme during the extended period.
This trough will keep the weather in the extended potentially
unsettled at times...with slightly below normal temperatures.
Tuesday...a weak short wave and secondary cold front will traverse
across the region. There will be chances for showers and
thunderstorms...mainly north of I-90...mainly during the afternoon.
Temperatures will still be about seasonable that day...80-85
valleys...middle to upper 70s higher terrain.
Tuesday night these features move east. There could still be a few
lingering showers mainly in the mountains during the
evening...otherwise it turns a little cooler with lows 55-60 Albany
south...50-55 further north along with partial clearing.
Wednesday looks to be a pretty nice day. Clouds will mix with
sunshine as a cold pool aloft makes for increasing afternoon
instability. There could be a few showers north of the capital
region. High temperatures will be 75-80 in the valleys...only middle
60s to lower 70s across the higher terrain.
High pressure builds to our north Wednesday night. Meanwhile...some
sort of wave wave along a stalled out front looks to slide to our
south. Some guidance attempts to bring showers (possibly even a
shield of steady rain) northward on Thursday (friday on the Canadian
Middle Range model). For now...generally went no higher than slight
chances as much of the guidance has the showers staying just south
of our region during this time frame. There will be time to adjust
the probability of precipitation one way or another.
Lows Wednesday night will generally be in the 50s. Highs Thursday
will be similar to Wednesday. However...if it turns out to be
clouds and Rainier than current thinking...it could be an
unseasonably cool day.
It will be the same situation for Friday...so for now...generally
went went highs upper 60s to upper 70s which assume a thinner
cloud cover and only a slight chance of showers. If the Canadian
model pans out highs would be lower again on Friday.
By Saturday...both the 12z European and 12z GFS operational models
indicated some sort of rainfall across the region as a more
significant low pressure tracks northeast south of the coast much
like a winter Nor'easter. On this day...called it mostly cloudy with
30 probability of precipitation of showers for now. Highs are expected once again to only be
from the upper 60s to middle 70s.
Aviation /19z Saturday through Thursday/...
flying conditions are currently VFR at all taf sites. Regional
mosaic radar shows some isolated showers/thunderstorms developing
thanks to a nearby upper level trough. The best forcing is generally
east of the Hudson Valley region into northern New England. As a
result...will only include a tempo for reduced flying conditions at
kpsf...as most of the activity looks to remain east of
kgfl/kalb/kpou...although cannot totally rule out a brief light
shower through the early evening hours so will keep a vcsh for all sites.
Otherwise...scattered ceilings at 5-8 kft will be in place. West-northwest winds will be
around 10 kts with a few higher gusts...especially at kalb.
For overnight...the clouds look to clear out for most sites any
there won't be any chance for precipitation as the upper level shortwave
trough starts to shift away. Some lingering middle level clouds may
continue for the northern terminals. Winds look to become light or
calm. Some MVFR br may develop at kpsf late tonight due to recent
rainfall and clearing skies...otherwise it should remain VFR.
During the day on Sunday...sct-bkn middle level clouds will be in plce
with continued VFR conditions and no precipitation expected. S-SW winds
will increase to 5 to 10 kts.
Sunday night: no operational impact. No sig weather.
Monday: high operational impact. Breezy likely rain showers...tsra.
Monday night: high operational impact. Likely rain showers...tsra.
Tuesday: low operational impact. Slight chance of rain showers...tsra.
Tuesday night: no operational impact. No sig weather.
Wednesday: no operational impact. No sig weather.
Wednesday night: no operational impact. No sig weather.
Thursday: no operational impact. No sig weather.
minimal fire weather concerns through the weekend as an upper
level disturbance will result in isolated to scattered showers
and isolated thunderstorms today...and then expect fair and dry
weather tonight into Sunday.
Relative humidity will increase to 85 to 100 percent tonight with
some patchy fog. Min relative humidity values Sunday will drop to 35 to 45
percent during the afternoon.
The winds will become light and variable in direction at 5 miles per hour or
less tonight. The winds will be from the south to southwest at 5
to 10 miles per hour on Sunday with gusts to 20 miles per hour during the afternoon
residual convection will dissipate this evening with dry weather
expected Sunday. The chance for showers and thunderstorms
increases Sunday night and especially on Monday associated with a
cold front. Precipitable waters climb to between 1.25-1.75 inches so
thunderstorms will have the capability to produce heavy rainfall.
This may cause some minor flooding in poor drainage areas and
where training of storms were to occur. Rivers are rather low and
impact from the rainfall is expected to result within bank river
Isolated to scattered showers are expected into the middle week with
an upper level low...but little impact on the rivers is expected
in the aly Hydro service area.
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
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