Area forecast discussion
National Weather Service Albany New York
412 am EDT Sat may 18 2013
Synopsis...
a tranquil period of weather continues through this evening as
high pressure slides east of the region. Meanwhile...moisture over
the plains and the Mississippi River valley associated with a warm
front will approach during the second half of the weekend with an
increasing threat for showers on Sunday which will extend into
most of the upcoming next week.
&&
Near term /until 6 PM this evening/...
satellite imagery this morning reveals a canopy of high and some
middle level cloud cover over the southern 2/3rds of the County warning forecast area. The
northeast corridor of the Continental U.S. Remains embedded in a northwest
flow regime as a low pressure area in the vicinity of Prince
Edward Island and deepening trough axis over the inter-mountain
west. So cloud cover forecast will be challenge as we endure the
moisture embedded in the northwest flow. In addition...as the
surface high slides off the Atlantic Seaboard...the low level
southeast flow with marine origins will bring about the lower
status deck into the southern portions of the County warning forecast area. The rap/hrrr
and WRF-NAM nmm core even suggest some light showers developing
across portions of the Catskills and into the southern portions of
the middle Hudson Valley later this afternoon. We will place a slight
chance probability of precipitation and watch radar trends through the day for southern
portions of Ulster...Dutchess and Litchfield counties.
These clouds will also cause problematic temperatures forecast as
the southern portions where clouds are more prevalent may keep
temperatures a couple of degrees cooler than those further north where
sunshine should assist with favorable results. Generally...highs
this afternoon should climb into the l-M 70s for valley locations
and 60s for the higher terrain which is in line with MOS guidance.
&&
Short term /6 PM this evening through Monday night/...
the aforementioned low level moisture is expected to slowly advect
northward as the southerly flow increases off the Atlantic tonight.
There are subtle hints of either light rain showers or pockets of
drizzle could develop tonight...however...the bufr profiles
suggest the shear is quite light limiting mixing for drizzle
formation. So we will keep probability of precipitation just below slight chance.
Temperatures overnight with the increase cloud cover should be
rather mild with most locations into the 40s across the dacks and
into the southern greens with 50s elsewhere.
Sunday...combination of deeper middle and lower level moisture
advecting into the region with higher Theta-E air should result in
extensive cloud cover. Combine that with may sunshine and our
northwest flow regime with embedded subtle short waves should
bring about scattered showers for the region. However...heights
aloft are also forecast to rise so not expecting the coverage nor intensity
of showers to get too strong. Highs Sunday afternoon climb to near
70f for valley locations with 60s more common cwa-wide.
Sunday night...per the NCEP model suite and international guidance
suggest the deeper moisture profiles shift east of the region with
extensive lower level moisture lagging behind. With no distinctive
triggers and The Heights aloft continue to slowly rise...we will
keep slight chance probability of precipitation to account for any residual shower and
collaboration with neighboring offices. As dewpoints climb into
the 50s...overnight lows will be quite similar.
Monday...surface warm front will be migrating through the region
as surface dewpoints continue to climb through the 50s and into
the 60 degree range. With the increase in lower level moisture and
daytime heating...can not rule out a shower and/or a thunderstorm.
Wind field is expected to remain rather light with shear profiles
less than 20kts. Should see some breaks in the cloud cover as
temperatures climb into the 70s.
Monday night...an increasing baroclinic zone sets up across the
Great Lakes region and into the St Lawrence Valley. This should
assist with low level focus for convection as instability across
our region remains favorable to keep the chance-scattered probability of precipitation in the
forecast. A rather warm and muggy night is expected as the region
will be deeper in the warm and moist sector with lows generally
into the 60s some 50s across the higher terrain.
&&
Long term /Tuesday through Friday/...
much of the extended period appears to be unsettled as a slow moving
frontal boundary will be situated close to the region.
While a ridge at 500 hpa sets up across the southeastern US...an
upper trough situated northwest of the region will slowly approach.
Our region will on the northern periphery of this upper level ridge.
With a surface boundary just north of the area...there will be a chance for
showers and thunderstorms for Tuesday through Friday. It/S
difficult to Pin Point any particular day that will have more or
less activity...although coverage of rain showers/thunderstorms and rain will probably be most
extensive during the afternoon and evening hours each day. By late in the
week...a strong shortwave will finally move from the Great Lakes and
into the northeast...and sweep the surface boundary through the area on
Friday. This should end the threat for precipitation for the weekend.
The models show 850 hpa temperatures to be above normal each day...although
they disagree on just how warm it will get. The 00z GFS is a little
warmer than the 00z European model (ecmwf)...which is continuing a trend it has shown
for a few runs now. For now...will go with above normal
warmth...although perhaps not quite as warm at the GFS and mex
guidance for Tuesday due to possible clouds/precip. Still...maximum
temperatures look warm with upper 70s to low 80s for valley areas for
Tuesday...and middle to upper 70s for valley areas for Wed/thurs. Maximum
temperatures look to reach the low 70s for Friday. Temperatures will be a little
cooler for the hills and mountains overnight lows will be mild with the
clouds around...with 50s to low 60s each day.
&&
Aviation /06z Saturday through Wednesday/...
VFR conditions look to continue at kalb/kpsf/kpou through the entire
taf period as middle and high level clouds continue to stream over the
region. Further north...there are less clouds...and the clearer
skies have allowed temperatures at kgfl to drop quickly. This may allow for
a period of MVFR fog to develop there late tonight. At this
point...the lack of recent rainfall and low dewpoints would suggest
the formation of IFR fog is unlikely.
After sunrise...all sites will be VFR with just scattered-broken middle and high
level clouds with light surface winds. This will continue through the
day on Saturday and into the evening hours. Ceilings will likely become
broken at 5-8 kft at all sites by late Saturday evening...but VFR
conditions should continue.
Outlook...
Sat night-Sun morning...VFR...no sig weather.
Sunday afternoon...VFR...isold- scattered -shras.
Monday...VFR. Slight chance/chance -shras/-tsras.
Tue-Wed...VFR/MVFR. Chance -shras/-tsras.
&&
Fire weather...
per coordination with our state partners...all areas have reached
green up.
Light and variable winds this morning will become southerly
through the afternoon at speeds less than 10 miles per hour...which continue
into tonight.
Relative humidity values will lower to 25 to 35 percent this
afternoon and recover to greater than 90 percent tonight. Values
remain relatively high on Sunday between 50 and 70 percent.
&&
Hydrology...
overall quantitative precipitation forecast through the weekend should remain at or below one
tenth of an inch with the chance of showers beginning this
afternoon across southern portions of the Catskills and middle Hudson
Valley and across the entire region on Sunday. Chance for more
appreciable rainfall arrives during the middle and 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...bgm
near term...bgm
short term...bgm
long term...frugis
aviation...frugis
fire weather...bgm
hydrology...bgm
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