Area forecast discussion
National Weather Service Albany New York
1050 PM EDT Monday may 20 2013
Synopsis...
warm and humid conditions will continue tonight with a frontal
boundary becoming stationary across upstate New York and northern
New England. A disturbance moving along the frontal boundary will
focus some showers and thunderstorms. The humid and unsettled
weather continues Wednesday and Thursday with more chances of
showers and thunderstorms.
&&
Near term /until 6 am Tuesday morning/...
the forecast area is expected to remain entrenched in the warm and
humid air mass with surface dewpoints in the u50s to m60s overnight as a
frontal boundary sags southward into the area. There is a line of
convection over the Great Lakes region moving eastward as a weak
wave/low moves along the boundary. Have added thunder to the overnight
forecast. Have kept patchy fog in for the overnight hours. Stratus
may also develop with a light S/southeast flow in the boundary
layer...especially south and east of aly.
Lows temperatures will be on the mild and muggy night with temperatures running
about 10 to 15 degrees above normal. The warmer metmos temperatures were
accepted with lows in the lower to m60s from the Mohawk
Valley...capital region...Saratoga region...Berkshires south...and
middle and u50s to the north and west.
&&
Short term /6 am Tuesday morning through Wednesday night/...
tomorrow...a surface wave moves into the upper Midwest/western Great Lakes
region...as the h500 ridge axis begins to flatten over New York and New
England. The frontal boundary that starts out stationary over the
region begins to lift back northward as a warm front during the
afternoon. A middle level short-wave approaches in the west/northwest flow
aloft. A weak surface wave moves along the boundary focusing some
showers and thunderstorms. The better instability looks to be from
the capital region south and east with the GFS/NAM hinting at some
sbcapes in the 1000-2000+ j/kg range. There is much less
instability to the north. The better 0-6 km bulk /deep layer/ shear is
strongest north of the capital region...with 30 kts or less to the
south. The middle level lapse rates are not ideal off the NAM with
generally less than 6 c/km...with the GFS hinting at some middle
level lapse rates closer to 6.5c/km south and west of kalb in the
late afternoon and early evening. The best shear and instability
are out of phase...but if a cluster or complex gets going with
the wave there could be a few stronger storms with an isolated severe
threat. The see text from Storm Prediction Center looks reasonable. The unfavorable
lapse rates would indicate less of a hail threat...and a greater
isolated wind threat with perhaps some bowing segments. Will mention
an isolated threat in the severe weather potential statement. The probability of precipitation were kept in the chance category
in the afternoon with some likely values over the southern dacks.
The other inhibitor for any stronger to isolated severe thunderstorms and rain showers will be
the amount of surface destabilization. The best chance of sunshine
appears to be south of capital region where we have the highest
temperatures forecasted with h850 temperatures of +15c to +16c. Expect highs in
the lower to m80s from the capital district south in the
valleys...and middle and u70s over the higher terrain. The southern
dacks...and southern greens will have maximum temperatures mainly in the u60s to
m70s...with middle and u70s in the valleys.
Tuesday night...the aforementioned wave continues to move along the
boundary prior to midnight with showers and thunderstorms...and
then the warm front starts to lift further north and east. The
better thermal gradient...and the low-level surface-h850 baroclinic
zone sets up over the northern zones where likely probability of precipitation were kept in for
showers and a chance of thunderstorms. The elevated instability wanes
after 06z with showalter values in the 0 to -2c range on the NAM.
Another muggy night is expected with temperatures in the m50s to m60s.
The majority of the guidance agrees the best chance for moderate
rainfall amounts of around a half an inch or more will be over the
northern half of the hsa.
Wednesday-Wednesday night...our forecast reflects a little lull in the showers and
thunderstorm activity in line with the latest NAM during the
morning with a chance of showers over the northern extreme...and a
slight chance over the southern two thirds. Hence...we are buying into the
forecast area busting back into the warm sector with the boundary near
northern New York and New England. H850 temperatures rise further to +15c to +17c
over the entire forecast area...with possibly some light SW winds
setting up in the boundary layer. Forecasted some middle and even
spotty u80s in the valleys /especially near kpou/...with u70s to
l80s over th hills and mountains another wave will be approach from
the Great Lakes region...and a prefrontal trough will focus some
showers and thunderstorms in the late afternoon...especially for
the western zones. A chance of showers and thunderstorms was included.
Precipitable waters will be in the 1.25-1.67" range...a couple of Standard
deviations above normal for some heavy bursts of rainfall. Some
much needed rainfall for the hsa.
Overnight...the question will be how close the frontal boundary
gets towards the forecast area. The latest run of the European model (ecmwf) has the
front and its associated showers and thunderstorms into the northern
tier of the forecast area between 06z-12z. The GFS/NAM are slower with
their respective model runs. For now...likely probability of precipitation have been used
from the capital region north and west overnight...with high
chance values to the south. Thursday morning looks like the
stickiest of the stretch with lower to m60s everywhere...except
some u50s over the southern Green Mountains and southern dacks.
&&
Long term /Thursday through Monday/...
active start expected to start the long term period as a cold front
is expected to drop southeast from near the Canadian border Thursday
morning. The cold front is expected to cross our region Thursday
afternoon and evening and be southeast of forecast area Friday morning with a
wave of low pressure moving northeast along it. This wave may keep
showers going on Friday. The upcoming Holiday weekend looks dry but
cool.
Thursday and Thursday night...expect a good deal of clouds which may
taper convection some although there are quite a few favorable
factors for at least scattered thunderstorms. Mlmucapes ahead of the
front reach 1500-2500 j/kg with 0-3 km helicities 60-120 m2/s2 while
upper level jet reaches 75-90 kts to the northwest of forecast area placing our
area in the right entrance region. Thus generally expect mostly
cloudy to cloudy conditions with showers and thunderstorms likely
mainly during the afternoon and early evening hours with activity
tapering to scattered showers after midnight. Expect highs on
Thursday to be in the upper 60s to upper 70s with lows Thursday
night in the middle 40s to upper 50s.
Friday...expect scattered showers during the morning with drier
conditions expected during the afternoon as coastal low moves
quickly departs northeast from southern New England coast Friday
morning. Highs on Friday are expected to be in the middle 50s to around
70.
Friday night through Sunday...a sprawling area of high pressure will
drop southeast from central Canada into the central US and build
eastward through the weekend. This will result in mostly sunny to
sunny skies and relatively cool conditions during the daylight hours
and clear to partly cloudy but chilly nights. Highs Saturday and
Sunday are expected to be in the upper 50s to upper 60s with lows in
the middle 30s to middle 40s with some lower 30s possible across the
western Adirondacks.
&&
Aviation /03z Tuesday through Saturday/...
tough forecast with the local area expected to remain entrenched
in the warm and humid air mass with dew points in the upper 50s
to middle 60s as a frontal boundary sags southward into the local
area. Patchy fog is expected to develop with light to calm winds.
Also stratus should form with a light S/southeast flow in the boundary
layer. MVFR conditions are expected to develop overnight due to
fog. IFR conditions are expected at kpou and kpsf due to fog and
ceilings with MVFR at kalb and kgfl due to fog and ceilings. Conditions
will gradually improve Tuesday morning with VFR expected by
afternoon. The frontal boundary over the region will lift back
northward as a warm front during the afternoon. A weak surface
wave/low will along the boundary focusing some showers and
thunderstorms.
Outlook...
Tuesday night...VFR/MVFR. At kalb and kgfl -shra likely with chance thunderstorms and rain.
At kpsf and kpou chance -shra/-tsra.
Wednesday...VFR/MVFR. Chance -shra/-tsra especially during the afternoon.
Wednesday night...VFR/MVFR. At kgfl and kalb -shra/-tsra likely. At
kpsf and kpou chance -shra/-tsra.
Thursday...MVFR with IFR possible. -Shra/-tsra likely.
Thursday night...VFR/MVFR. Chance -shra/-tsra especially in the evening.
Friday...mainly VFR. Chance -shra mainly in the am.
Sat...vfer. No sig weather.
&&
Fire weather...
warm and humid conditions will continue tonight with a
frontal boundary becoming stationary across upstate New York and
northern New England. A disturbance moving along the frontal
boundary will focus some showers and thunderstorms tomorrow into
tomorrow night. The humid and unsettled weather continues Wednesday
and Thursday with more chances of showers and thunderstorms.
No fire weather concerns are expected over the next several days
in the warm and humid air mass. Intermittent showers and
thunderstorms are expected into Friday.
The relative humidity values will increase to 80 to 100 percent tonight...and
lower to 55 to 70 percent tomorrow afternoon. An excellent
recovery with relative humidity values increasing to 85 to 100 percent Wednesday morning.
The winds will generally be less than 10 miles per hour the next few
days...except stronger gusts in thunderstorms may be possible.
&&
Hydrology...
no widespread Hydro service areas problems are expected the next 5
days. Some locally heavy downpours of rainfall may occur through
the middle week in the humid air mass. 3-hour zonal ffg values are
generally in the 2.4-3.1 inch range at this time...which are high
for middle to late may.
Due to the scattered nature of the showers and thunderstorms...
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 /Tue night through Thu/. The
nerfc quantitative precipitation forecast was used prior to Thursday with the heavier amounts from
the capital region and Mohawk Valley northward with one to two inches
possible in some areas.
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/wasula
near term...iaa/wasula
short term...wasula
long term...11
aviation...iaa
fire weather...wasula
hydrology...frugis/wasula
