Scientific Forecaster Discussion
Area forecast discussion...corrected
National Weather Service New York New York
405 am EDT Sat may 23 2015
high pressure settles across the area today and will start to move
offshore tonight. This will become well established offshore as a
Bermuda high closing out the weekend into the new week. There will
be an approaching warm front Monday that will move north of the
region Monday night with the aforementioned Bermuda high persisting
Near term /until 6 PM this evening/...
a very dry day in store with northwest flow to start. This should promote
quick diurnal warming after daybreak. 850mb temperatures as well as surface
temperatures will be on the rise with full sun and downslope flow. The
pressure gradient weakens this afternoon...allowing for sea
breezes to move in.
The highs today will be a little cooler...well into the 60s for a
majority of the area.
Short term /6 PM this evening through 6 PM Sunday/...
tonight Marks the commencement of the transition of airmass to a
warmer more humid one as high pressure settles offshore with warm
air advection occurring with SW flow increasing through the
atmospheric column. This is diagnosed from 850mb temperatures increasing
a few degrees through the night. Lows will convey a vast
range...upper 30s for rural Countryside to upper 50s for NYC.
For Sunday...warm and moist air advection will result in a warmer
day with higher dewpoints with southwest flow increasing. The
pressure gradient will become tighter as high pressure shifts
farther offshore. The dry weather will continue.
Long term /Sunday night through Friday/...
for Sunday night and into the new week...the jet stream will be
pushing north of the region with high pressure persisting
offshore. This will essentially become a Bermuda high. The warm
and moist air advection will continue. Maximum temperatures and dewpoints
will be on a steady rising trend going through the week.
A warm front moving across Monday into Monday night will allow for
more warm and moist air advection behind it. There will be a
slight chance for showers and thunderstorms north and west of NYC
Monday afternoon with daytime instability and frontal boundary in
More of a diurnal convective scenario proceeds for the remainder
of the forecast period as ridge amplitude moves east of the region
and capping aloft is not as prominent. The showers and
thunderstorms will be primarily confined to western interior
portions of the region where greater instability will reside.
Farther east...less instability will keep chances for showers and
With persistent southerly flow...expecting patchy fog for late
night into early morning hours middle to late week as the airmass
becomes increasingly warm and humid.
Aviation /08z Saturday through Wednesday/...
high pressure will build to the south of the area today.
VFR with mainly clear skies through the taf period.
Northwest flow should diminish as the morning progresses. Winds then back to
the west...then SW around 10 knots during the day today. Gusts in the
teens also possible during the afternoon. Stronger S/SW flow at kjfk
due to possible sea breeze influence. Winds diminish this
evening...generally from the S/SW.
Outlook for 06z Sunday through Wednesday...
Sun...VFR. SW winds 10-20kt.
Monday...VFR. SW winds 10-20kt.
Tuesday...morning MVFR or lower possible in fog/stratus. SW winds.
Wednesday...pockets of MVFR or lower possible in fog/stratus. SW
will cancel the Small Craft Advisory as gusty northwest winds diminish this morning. The
winds shift to the west...then SW as high pressure passes to the
east. This high drifts east tonight and Sunday. In fact...this high
will remain nearly stationary over the western Atlantic for several
days. As such...a persistent SW/S flow will prevail across the
waters through at least the middle week period.
In general...winds should remain below Small Craft Advisory criteria Sunday through
Wednesday with warmer air moving over the cooler waters. Some near
shore gusts each afternoon may approach Small Craft Advisory levels...especially
around stronger afternoon sea breezes that may develop.
However...with a persistent southwesterly flow...seas on the ocean
waters are expected to eventually build to small craft levels. This
would most likely occur Monday night with seas then remaining at
small craft levels into Wednesday.
with daytime mixing and northwest flow...dewpoints will lower
into the 20s and upper teens as temperatures rise into the 60s.
The resulting relative humidity values will drop to 15 to 30
percent this afternoon into the early evening. The wind speeds
will be generally 10 to 15 miles per hour on average with gusts up to 20 miles per hour
and occasionally up to 25 miles per hour. This will enhance the spread and
growth of any fires that develop.
no significant widespread rain expected through the forecast