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Area forecast discussion 
National Weather Service Albany New York
1230 PM EDT Wednesday Jul 23 2014

Synopsis...
hazy...hazy...hot and humid conditions expected this afternoon ahead
of a cold front. This cold front will bring showers and
thunderstorms to the area through this evening. Behind the cold
front...cooler and less humid air is expected for Thursday and
Friday.

&&

Near term /through tonight/...
as of 1230 PM EDT...radars indicated a few cells popping up across
northern Herkimer and portions of central New York. The cold front
was working through the Saint Lawrence valley with perhaps a
pre-frontal trough setting up well to the west of the Hudson
Valley.

Temperatures were already into the middle 80s in the Hudson Valley so
for this update went ahead and bumped some of these up several
degrees...which would mean the capital region should approach or
even eclipse 90 degrees.

So for this update...bumped temperatures upward...re-tooled hourly
grids but left the remainder of the forecast alone.

Area 12z soundings show quite a bit of instability over the
region...especially upstream...where convection is expected to
initiate early this afternoon. We are capped at midlevels here in
eastern New York and western New England but again...upstream...the cap
is much less.

Boundary layer winds are not too strong...but enough so that
thunderstorm downdrafts will enhance the winds for a damaging wind
threat in thunderstorms through this evening. Low level winds are
light from the south and southeast over eastern New York now...but west
to southwest in central and western New York. Will have to see if low
level winds remain south to southeast in eastern New York...as shear
could be enough for stronger rotating thunderstorms.

It could be a busy afternoon and evening with regard to coverage an
strength of thunderstorms...with a damaging wind and large hail
threat. The latest hrrr indicated activity in our region should
Blossom between 2 and 5 PM.

More analysis of guidance was described in the previous afd which
is below...

The warm sector is well entrenched across the region as metar
dewpoints were between 65-70f and very little in the way of cloud
cover. This will set the stage for an active weather day across
the region /as already seen upstream with a line of strong
convection underway/ as good insolation...high moisture content
as precipitable waters climb to near 2 inches...sbcapes at or above 2k j/kg and
deep layer shear around 30kts /the higher values across the
northern portions of the region/ to support the extension of the
slight risk per Storm Prediction Center coordination across the entire region. The
main threat remains from damaging wind gusts and/or wet
microbursts given the precipitation loading in a very moist column. Hail
potential looks low at this time as wet bulb freezing levels per
the bufr profiles are expected at or above 13k feet. We will
retain the enhanced wording for heavy rainfall and gusty winds in
the grids along with the strongly worded severe weather potential statement. NCEP model suite is
in good agreement with the timing of the frontal passage which reaches our
dacks region around the lunch hour...capital region between 2pm-
4pm...and the middle Hudson Valley and northwest CT between 5pm-8pm.

In the wake of frontal passage...winds shift to west and northwest before
midnight. However...a wave is expected to develop along the
boundary which will slow down the forward progress somewhat to
keep chance-scattered probability of precipitation south of i90. While this frontal passage will usher in
more stable and less humid conditions...low level moisture content
remains high so we will retain the partly-mostly cloudy skies in
the forecast.

Highs today will be near 90 in most valley locations...with heat
indices into the middle and upper 90s. Higher terrain will see highs in
the middle to upper 80s...except cooler across the adriondacks where
clouds and showers should keep highs below 80. A south wind 5 to 15
miles per hour will do little to stifle the heat. However...the showers and
thunderstorms will begin to cool US down after 400 PM.

&&

Short term /Thursday through Friday/...
a more stable...cooler and less humid air mass advects into the
region Thursday and Friday as high pressure builds into the
region. Residual cloud cover across the region...especially across
the southern portions of the region...will mix out to partly
cloudy/sunny conditions. Cyclonic flow aloft remains aloft a h850
temperatures dip back to around 10c. Highs Thursday will average at or
just below 80f for valley locations with Thursday night lows into
the 50s with 40s across the dacks and portions of the Mohawk
Valley. Highs Friday rebound back into the lower 80s for valley
locations...mid-upr 70s elsewhere.

&&

Long term /Friday night through Tuesday/...
the long term period looks rather unsettled starting with the second
half of the weekend.

For Friday night and Saturday expect dry and seasonable conditions
as a ridge of high pressure slides off the eastern Seaboard. Expect
lows Friday night in the 50s with highs on Saturday in the middle 70s
to middle 80s.

Start to increase probability of precipitation from slight chance Saturday evening to chance
probability of precipitation late Saturday as forecast area starts to be converged upon by several low
pressure systems one passing through the middle Atlantic region and a
second one passing through the upper Great Lakes region. Lows
Saturday night are expected to be in the middle 50s to middle 60s.

Sunday through Tuesday looks to be active as the series of low
pressure systems converge across the northeast. Timing and location
of individual low pressure systems differ amongst the models. So at
this point in time will place chance probability of precipitation in the grids through the
period with mainly afternoon and evening showers and thunderstorms.
Highs are expected to range from the middle 70s to middle 80s Sunday and
Monday and in the upper 60s to upper 70s on Tuesday. Lows are
expected to be in the middle 50s middle 60s.

&&

Aviation /18z Wednesday through Monday/...
for today...mainly VFR conditions...but some intermittent MVFR
ceilings at kpsf from 12z-14z. Showers and thunderstorms will occur
across the area as a cold front approaches and interacts with the
very warm and humid air mass in place across the region. There are
now indications that the front will slow down as a wave of low
pressure moves northeast along it. Have used prob30 groups for MVFR
conditions...bordering on IFR...to address the timing of the
convection...for the late afternoon into the evening hours.

Some storms may become strong to severe during the afternoon and
evening hours.

We will start off with a south-southwest wind of 5 to 10 knots today
shifting more to the west and then northwest in the wake of the cold
front during the evening hours.

Outlook...

Thursday night: no operational impact. No sig weather.
Friday: no operational impact. No sig weather.
Friday night: no operational impact. No sig weather.
Saturday: no operational impact. No sig weather.
Saturday night: low operational impact. Chance of rain showers.
Sunday: moderate operational impact. Chance of rain showers...tsra.
Sunday night: moderate operational impact. Chance of rain showers.
Monday: moderate operational impact. Chance of rain showers...tsra.

&&

Fire weather...
showers and thunderstorms will move across the region today along
and ahead of a cold front. Relatively high moisture content ahead
of this boundary will keep relative humidity values at or above 50 percent. The
relative humidity values tonight at better than 80 percent.

The surface wind will be south to southwest this morning at 5 to 10
miles per hour...then becoming southwest to west middle day at 5 to 15 miles per hour with
some gusts to 20 miles per hour. Winds shift to a west then northwest
direction tonight.

&&

Hydrology...
showers and thunderstorm will occur across the area as a cold
front approaches and interacts with the very warm and humid air
mass in place across the region. Precipitable water values are
expected to increase near 2 inches...so any storm will capable of
very heavy downpours which could cause localized flooding of low
lying and poor drainage areas. Have continued enhanced wording for
the heavy rainfall to the forecast for this afternoon and evening
and will retain this mention in our hazardous weather outlook.

With the passage of the cold front...a cooler and less humid air
will be ushered in. Expected some lingering showers into Thursday
morning as the front will be slow to move off to the east. Then
looking at dry weather into at least the first half of the
weekend. The weather will turn unsettled as we head into the
second half of the weekend and into next 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.

&&

Aly watches/warnings/advisories...
CT...none.
New York...none.
Massachusetts...none.
Vermont...none.

&&

$$
Synopsis...hwjiv/bgm
near term...hwjiv/bgm/NAS
short term...bgm
long term...11
aviation...11
fire weather...bgm
hydrology...bgm

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