Scientific Forecaster Discussion
Area forecast discussion
National Weather Service New York New York
1027 am EDT Monday Aug 3 2015
high pressure tonight will give way to a slow moving cold front
late Monday and Monday night. The cold front moves east of the
area late Tuesday. Weak high pressure builds into the area on
Wednesday. Several waves of low pressure may impact the area for
the end of the week. High pressure builds back in for the weekend.
Near term /until 6 PM this evening/...
forecast on track this morning. Low pressure now east of the
Hudson Bay in Quebec will continue to slowly move east-
northeastward...with an attendant cold front moving towards the
area through the day. A mostly sunny day is expected
overall...with some increase in clouds late in the day.
Despite temperatures into the lower 90s...instability is will generally
be weak with near normal to slightly below average precipitable water values and dew
point temperatures around 60. Bulk shear is around 30 kts...but still
low. Ncar ensemble is dry as are local Stony Brook WRF runs and
the NCEP deterministic runs. Only exception to no convection is
the Storm Prediction Center WRF which generates a convective cluster around 3 PM local
in north Jersey that tracks east-northeast across the city. The operational
hires run has some idea about this as well...but less intense and
Based on themodynamic analysis...will stick with a dry forecast
through the early evening hours.
Temperatures are towards the warmer GFS MOS numbers.
Sea breeze enhanced with the Ambrose jet effect and gusts to near
30 miles per hour late this afternoon over western Long Island. As such...there is
a high risk for the development of rip currents at the ocean
beaches today as southerly flow increases. A rip current statement
is in effect.
Short term /6 PM this evening through 6 PM Tuesday/...
cold front sags into the region by Tuesday morning and then
becomes diffuse. Rather uncertain on details for precipitation in this
period. Have continued the idea of scattered convection into Tuesday
Temperatures remain above normal on Tuesday with highs into the lower
Long term /Tuesday night through Sunday/...
deep closed upper low will slowly move from south central Canada
into eastern Canada through the end of the week. This will result in
upper level troughing over the region. A cold front will move
offshore Tuesday night followed by high pressure on Wednesday. Much
drier air moves in on Wednesday with dew points in the 50s. Some
upper level energy rotating through the upper trough approaches in
the afternoon...but feel at this time the air mass will be too dry
for any showers. Have left the forecast dry for Wednesday.
By Thursday...models begin to diverge on a piece of energy
interacting with the upper trough across the Midwest. This shortwave
energy may then move along the base of the trough through the area
late Thursday into Friday. Several waves of low pressure are
forecast to develop along a frontal boundary south of the area and
may impact the region. The 18z sun and 00z Monday GFS are flatter
with the wave and thus keep low pressure south of the area compared
to its previous 12z Sunday run...while the 00z Monday European model (ecmwf) is
consistent with its 12z run from Sunday indicating a more amplified
shortwave. This more amplified solution would bring the boundary and
waves of low pressure closer to the region. The 00z Monday CMC is
the most amplified and brings the low over the area Friday. The 00z
GFS appears to be an outlier as the 00z gefs are further north with
the low and more amplified with the shortwave. This system will have
large scale synoptic lift to work with...as the region looks to lie
in the right entrance region of an upper level jet over northern New
England. A widespread significant rainfall would be a possibility if
the more amplified and further north solutions come to fruition.
Have continued with previous forecast of chance probability of precipitation due to
uncertainty at this time frame.
The frontal boundary and waves of low pressure move offshore late
Friday night into Saturday as weak high pressure builds back into
the region for the weekend with a return to dry conditions.
Temperatures will be near seasonable levels on Wednesday...and then
average near or slightly below average through the rest of the long
Aviation /15z Monday through Friday/...
high pressure will give way to an approaching cold front this
evening and overnight.
VFR through the afternoon and tonight.
S/SW flow will increase and become gusty in the afternoon. Strong
seabreeze development expected at coastal terminals. Gusts into the
low to middle 20 knots range expected...strongest at kjfk.
There is a low probability for southeast seabreeze to work into kewr/kteb.
There will be a chance of thunder late this afternoon/evening at
kswf. Elsewhere...probabilities are too low to include in the taf at
Patchy fog is possible tonight...outside of the NYC metropolitan
New York metropolitan enhanced aviation weather support...
Detailed information...including hourly taf wind component forecasts can
be found at: http:/www.Erh.NOAA.Gov/zny/n90 (lower case)
Kjfk fcster comments: high confidence of gusty winds this afternoon
with the seabreeze. Timing of gusts may be off by +/- hour.
Klga fcster comments: timing of gusts may be off by +/- hour.
Kewr fcster comments: low chance of seabreeze development. Winds may
become southeast for brief period after 20z.
The afternoon kewr haze potential forecast is green...which implies
slant range visibility 7sm or greater outside of cloud.
Kteb fcster comments: low chance of seabreeze development. Winds may
become south/southeast for brief period after 20z.
Khpn fcster comments: gusts may be occasional this afternoon.
Kisp fcster comments: high confidence of gusty winds this afternoon
with the seabreeze. Timing of gusts may be off by +/- hour.
Outlook for 12z Tuesday through Friday...
Tuesday...chance of thunderstorms. Cold frontal passage with S winds shifting to west.
Wednesday...VFR. West flow.
Thu-Fri...MVFR or lower conds possible in mainly
a cold front approaches the waters late today...moving close to
the waters tonight. Winds out ahead of the front increase Monday
afternoon into Monday night before lightening with the approach of
Ocean seas build due to the increase in these winds. Small Craft Advisory
starting at 4 PM local and through tonight. Occasional 25 knots
gusts possible for New York Harbor...western South Shore bays and
western Li sound late Monday after into Monday evening.
Ocean seas will be subsiding Tuesday night...but 5 feet seas may
linger on the eastern ocean until Wednesday morning. Weak high
pressure passes over the waters on Wednesday with sub Small Craft Advisory conditions
expected. Several waves of low pressure may pass over the waters for
the end of the week. Occasional Small Craft Advisory conditions are possible on
Friday...especially on the ocean.
thunderstorms tonight into Tuesday will product localized heavy
rainfall...which could lead to minor poor drainage nuisance flooding.
A widespread significant rainfall is possible late Thursday into
Friday. However...a large amount of uncertainty exists with this
New York...high rip current risk from 2 PM this afternoon to 9 PM EDT
this evening for nyz075-080-081-178-179.
Marine...Small Craft Advisory from 4 PM this afternoon to 6 PM EDT
Tuesday for anz350-353-355.