Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Albany New York
159 PM EDT Tuesday Jul 22 2014
hazy...hot and humid conditions are forecast for today
and Wednesday. A cold front will bring showers and thunderstorms to
the area Wednesday and Wednesday night. Behind the cold
front...cooler and less humid air is expected for Thursday and
Near term /through tonight/...
as of 115 PM...visible satellite imagery shows scattered to broken
with isolate very small showers on radar. Will maintain mostly to
partly sunny skies for this afternoon with a slight chance of
showers. Highs will be 80 to 90.
Short term /Wednesday through Thursday/...
the Storm Prediction Center /spc/ continues to highlight an area
of slight risk for severe weather from the capital region and
locations to the north and east. Forecast instability parameters
are rather high and consistent with a severe weather episode for
the region. Sbcapes climb at or above 2k j/kg...precipitable waters up to 2
inches...bulk shears of 30-40kts and the timing of this front
coincides with the maximum daytime heating for the region. Local
mesoscale low level winds up the Hudson River could assist with
enhancing the low level helicity for a few of these cells to
exhibit potential rotation. Nevertheless...the main threat from
these thunderstorms will be from damaging wind gusts and cloud to
ground lightning strikes. High temperatures in advance of the cold
front should climb into the middle and upper 80s for many
locations...with the exception across the Adirondacks region where
clouds will likely increase early and cut down on the insolation.
The cold front is rather progressive and should continue to
progress southeast during the evening hours Wednesday. Convective
threat should diminish rather quickly with frontal passage as we will time
a decrease in probability of precipitation from northwest to southeast through the night.
A low level wind shift from the west-northwest will usher in drier
and more stable atmosphere. In fact...h850 temperatures drop near 10c
during the night. Lows will range from the upper 40s across
portions of the dacks to middle 60s for the middle Hudson
Valley...southern Berks and northwest CT.
On Thursday...cold front continues to track further southeast
leaving behind a very dry middle levels. However...very steep low
level lapse rates at or below h800 and still cyclonic flow aloft should
allow for scattered cumulus to develop through the day. Highs on Thursday
will average 10 degrees cooler with many locations remaining in
the 70s and some upper 60s for the higher terrain of the dacks.
Long term /Thursday night through Monday/...
a broad area of high pressure over the Ohio Valley and Middle
Atlantic States will extend into our region for Thursday night
through Saturday. This will provide several days of dry
weather...with comfortable humidity levels and seasonable temperatures
/highs mainly in the middle 70s to middle 80s...and lows in the 50s to
low 60s/. The only exception may be across the Adirondacks on
Friday...when a brief rain shower may be possible thanks to an
upper level disturbance situated north of the region over Quebec.
Otherwise...skies will be partly to mostly sunny throughout the
region with dry conditions.
The next chance for showers and thunderstorms will return for later
in the weekend and into early next week as a slow moving closed off
upper level low drops into the northern tier of the US from Canada.
With diffluent flow aloft ahead of this feature and a moist flow out
of the south...some showers and thunderstorms look possible for Sat
night through Tuesday. The best chance will be during the diurnally
favored afternoon and evening hours. Eventually...this system will lifts
back into Canada towards middle week...ending the threat for widespread
showers and thunderstorms.
Aviation /18z Tuesday through Sunday/...
VFR conditions are forecast at all taf sites through 04z. With very
muggy air in place...expect areas of fog and some low clouds to
develop overnight. Expect all taf sites to see some restriction in
visibility due to fog or haze tonight. IFR due to fog/low cloud is
forecast at kpsf. Elsewhere...MVFR forecast. After
daybreak...heating from sun and increasing winds ahead of
approaching cold front should help improve conditions
quickly...although visibility may be restricted all sites during
the day due to haze. Showers and thunderstorms will develop around
middle day Wednesday and linger into the overnight period. Some
storms Wednesday could bring gusty winds and 1+ inch hail to the
Winds through the taf period /18z Wednesday/ are forecast to be
from south to southwest at 5 to 15 knots although they will likely
become light and variable at most taf sites just before sunrise
Wednesday...before increasing again after sunrise.
Wednesday through Wednesday night: moderate operational impact.
Likely rain showers...tsra.
Thursday through saturday: no operational impact. No sig weather.
mainly dry weather is expected through early Wednesday. A stray
shower cannot be ruled out during the afternoon and early evening
Relative humidity values will be elevated through Wednesday with minimum values
generally at or above the 40-50 percentile range and overnight
lows generally at or above 90 percent.
By Wednesday...shower and thunderstorm activity will increase as a
cold front begins to impact the region...which will interact with a
hot and humid air mass.
The surface wind will be light or calm this early morning...becoming
west to southwesterly at 5 to 10 miles per hour this afternoon into tonight.
mainly dry weather expected through Wednesday morning with just a
low chance for a brief rain shower this afternoon.
By Wednesday...the threat for more widespread showers and
thunderstorms by afternoon...lingering into early Thursday. The
higher moisture content across the region...the chance for heavy
rainfall from thunderstorms will increase.
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.