Area forecast discussion
National Weather Service Albany New York
152 PM EDT sun may 19 2013
Synopsis...
increasing amounts of moisture and an approaching weak warm front
will allow for some showers today into tonight. Warmer
temperatures will return to the region for much of the upcoming
week...along with several opportunities for showers and
thunderstorms.
&&
Near term /until 6 PM this evening/...
as of 130 PM...current radar trends suggest the most widespread
shower activity this afternoon will occur over the northeast part of
the forecast area and have raised probability of precipitation there to likely. Further to
the southwest probability of precipitation decrease to only 20 percent over the southwest
fourth of the forecast area. These probability of precipitation are then forecast to lsowly
decrease to only slight chance in all areas this evening. Hourly and
maximum temperatures grids for today have been reduce by about 4 degrees with
highs for today now forecast to be in the middle 50s to lower 60s. Have
also increased the cloud cover to completely cloudy in most areas.
&&
Short term /6 PM this evening through Tuesday night/...
tonight...a wave of low pressure looks to pass well north of the
region across southern Canada. Some showers are still possible due
to the nearby wave and warm advection at middle levels during the
evening hours...but the threat for showers may lower somewhat
overnight. It still look to stay fairly cloudy...and min temperatures
will be in the 50s.
On Monday...our region will be a little bit of lull...with no
strong forcing over the area. However...the cold front associated
with the weak wave that passed to our north for Sunday night will
be situated just to the north of the area. The proximity of this
boundary...along with daytime heating and lingering low level
moisture in place...may be enough to allow for some showers or
isolated thunderstorms to develop. As a result...we will go with low
chance probability of precipitation across the entire area. With 850 hpa temperatures having warmed
to 10-13 degrees c...maximum temperatures will be warmer than Sunday...with
middle to upper 70s in most areas. The exact extent of the warming
will depend on just how many breaks of sun can occur.
With the loss of daytime heating...the threat for
showers/isolated thunderstorms will diminish on Monday night. We
will still go with slight chance to low chance probability of precipitation as the lingering
boundary will still be close to the region. Min temperatures will range
from the middle 40s in the Adirondacks to near 60 in the middle Hudson
Valley.
On Tuesday...most areas look to start the day dry. However...the
models show the threat for showers and possible thunderstorms
again by later in the day as a wave of low pressure moves into the
Great Lakes along the stalled frontal boundary. Maximum temperatures will
generally be in the 70s. We will continue chance probability of precipitation into Tuesday
night as the wave along the front may move across the region
during this time period with additional showers/thunderstorms. Min
temperatures look to range from the 40s north of the boundary across the
Adirondacks to near 60 across southern areas.
&&
Long term /Wednesday through Sunday/...
a rather active period of weather for the region with perhaps our
first significant round of convection before the Holiday weekend.
NCEP model suite and international guidance lead by the European model (ecmwf)
suggest a strong warm front passage to occur during Wednesday. This
will not only signify a warmer and more humid air mass but the
chance for convection along and ahead of this boundary. If enough
upstream instability were to be attained...this could make for an
interesting forecast with increasing wind shear and low level
helicity.
The warm front is forecast to lift north of the region Wednesday
night leaving behind a warm and humid air mass heading into
Thursday. Meanwhile...upstream trough is expected to amplify as a
potent short wave tracks from the Southern Plains and into the Great
Lakes region. This wave will amplify the synoptic pattern but its
surface frontal placement and strength differ...this is likely due
to several convective episodes in the model simulation that will
disrupt the synoptic features. Either way...this cold front is
expected to be a large player in the forecast for Thursday into
Thursday night time frame. The potential for another convective
episode is expected and with prognosticated surface dewpoints into the 60s
and forecast highs well into the 70s and lower half of the 80s.
Confidence is increasing that the cold frontal passage occurs late Thursday
night into Friday morning with improving conditions under a cooler
air mass originating from Canada. Just how cool remains to be seen
as the European model (ecmwf) wants to plunge those h850 temperatures below 0c with the GFS
a bit more modified with positive h850 temperatures. If the European model (ecmwf) were to
verify...this could signify the potential for some frost issues.
Temperatures for the upcoming week should be near to above normal
with precipitation near to above normal.
&&
Aviation /18z Sunday through Friday/...
MVFR/IFR ceilings and visibilities will continue to provide dismal
flying conditions through the taf period as scattered showers and
overnight fog develop in an increasingly moist low-level airmass.
This afternoon...scattered shower activity will continue to impact
all taf sites occasionally dropping ceilings and visibilities to IFR
levels. Have indicated tempo groups to account for uncertainty
regarding shower coverage/timing. In between these showers all taf
sites will remain primarily at MVFR levels as abundant low-level
moisture and a low stratus deck remain entrenched across the region.
Tonight into Monday...shower coverage will begin to diminish this
evening...however cannot rule out an isolated shower affecting the
taf sites through the remainder of the taf period. Light winds and
saturated low-levels will allow for IFR fog/low stratus development
towards daybreak at all taf sites. Flying conditions should improve
to VFR after 12z Monday...with vcsh persisting.
Southerly winds will be generally around 5-10 knots this afternoon
with occasional gusts to 20 knots where the flow can be channeled.
Winds will diminish to near calm overnight before increasing
slightly to around 4-8 knots Monday.
Outlook...
Monday night-Fri...VFR/MVFR. Chance -shras/-tsras.
&&
Fire weather...
relative humidity values will only drop down to 50-65 percent today with scattered
rain showers...especially for southern and eastern parts of the
region. S-southeast winds will average around 6-12 miles per hour today. Relative humidity values
will return to near 100 percent tonight with a few additional rain
showers and continued light southerly winds. There will be a
continued threat for rain showers into the upcoming week with
relatively high relative humidity values and light winds.
&&
Hydrology...
some scattered light rain showers are possible today into tonight.
Up to a quarter of an inch of rainfall is possible...mainly across
the higher terrain of the Catskills and greens.
There will be a continued threat for showers and possibly
thunderstorms during much of the week. Due to the scattered nature
of the showers...basin average quantitative precipitation forecast will be highly variable this
week. The best threat for seeing significant amounts of showers or
thunderstorms will be during the middle to late week period.
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...iaa/frugis
near term...gjm/iaa/frugis
short term...frugis
long term...bgm
aviation...irl
fire weather...frugis
hydrology...frugis
