Area forecast discussion
National Weather Service Albany New York
400 am EDT sun may 19 2013
Synopsis...
increasing amounts of moisture and an approaching weak
warm front will allow for some showers today into tonight...
especially across southern and eastern parts of the area. 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 400 am EDT...the northeastern US remains on the northern
fringe of a ridge over the Ohio Valley and southeastern
US...allowing for weak northwest flow over our area at 500 hpa. The infrared
satellite imagery this morning shows plenty of middle/high level
clouds streaming into our area from the northwest thanks to a departing
jet streak off the New England coast. At the surface...high pressure
has retreated off the eastern Seaboard...allowing for a light S-southeast
flow at both low and middle levels. With a moist flow off the
Atlantic...some light rain showers have developed across southeastern New York
and New Jersey in response to the weak warm advection at the middle levels.
During the morning hours...there will be an increasing threat for
rain showers across the southern half of our area as the warm air advection
increases over our area. While the surface warm front will still be
well to our south and west...there will probably be just enough
forcing along with the increasing moisture to allow for the chance of
showers across the entire area by afternoon. The highest threat will be
southern and eastern portions of the County Warning Area this afternoon...where
the warm air advection looks strongest and the terrain of western New England may
locally enhance the threat for showers. See the Hydro section for
details on how much precipitation we expected today.
With plenty of clouds expected today...maximum temperatures will be held down
somewhat. Highs look to to be mainly in the 60s...with the highest
temperatures across northwest parts of the area...where the clouds may be
thinnest and the threat for showers will be lowest.
&&
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 Saturday/...
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 /08z Sunday through Thursday/...
while VFR conditions continue this early Sunday morning...lower
level MVFR stratus was slowly advancing northward and this trend is
expected through the morning hours. This MVFR deck will produce
scattered-num showers for the region as the surface warm interacts with
this deeper moisture through the daylight hours. There is a chance
for IFR conditions to impact kpou-kpsf where the combination of
deeper moisture profiles and upslope may lower the cloud ceilings within
the showers this afternoon.
Tonight...most of the showers will either weaken or be east of the
region as we remain embedded in a rather moist atmosphere. This is
where flight trends from low end MVFR to high end IFR conditions may
become more prevalent.
Winds will remain at speeds less than 10kts overnight /many
locations are light and variable/...with a southerly breeze
developing after sunrise with some wind gusts in the Hudson River
valley to between 10 and 20kts.
Outlook...
Sun night...MVFR...chc IFR. Slight chance or chance -shras.
Monday-Monday night...VFR/MVFR...chc -shras/slight chance -tsras.
Tue-Thu...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...frugis
near term...frugis
short term...frugis
long term...bgm
aviation...bgm
fire weather...frugis
hydrology...frugis
