Scientific Forecaster Discussion
fxus61 kokx 211807
Area forecast discussion
National Weather Service New York New York
207 PM EDT Sat Oct 21 2017
mild weather continues through the weekend. A cold front brings
rain to the region on Tuesday that may linger into Wednesday as
temperatures cool. High pressure builds back in by late in the
Near term /until 6 PM this evening/...
the forecast is mostly on track. Minor adjustments to hourly
temperatures and dewpoints were made to capture the latest
trends. Sunshine will be filtered through some cirrus from time
to time. Warm and dry conditions as high temperatures average
mostly in the mid to upper 70s, and a few 80 degree readings
possible in the city and urbanized areas of NE New Jersey. This is about
15 degrees above average, but short of record values. Islip
still has a chance to tie or break the record of 76 set last
year. An oncoming sea breeze may stop that from happening
Short term /6 PM this evening through Monday/...
cirrus starts to increase on Sunday and we're partly to mostly
cloudy on Monday as warm advection increases aloft. Max temps
lower slightly due to the cloud cover, but still well above
Long term /Monday night through Friday/...
well, it sure appears that it will actually rain! Analysis of
the 00z gefs suggests cold frontal passage consensus timing is focused on
Tuesday evening in the local area as a rather potent cyclone
occludes over the Great Lakes. Note that the European model (ecmwf) deterministic
run suggest a slightly slower and prolonged passage.
The GFS bufr wind data has impressed ME with the narrow cold
frontal rain band. Standardized anomalies and the ensemble
situational awareness table indicate +3 Standard deviation in
the 925 hpa southerly winds in the gefs with the deterministic
GFS run getting up to +5 or more. Thus, the threat for at least
Wind Advisory (gust 40+ kt) criteria is increasing - especially
for Long Island and southern CT.
Did remove the thunder from the forecast as there's no cape and
all indices do not support it.
Beyond Tuesday night, uncertainty is high as for how much, if
any rain we get Wednesday. The majority of the gefs members keep
the rain offshore. The local forecast is trending this
Temperatures average above normal through the period with
Thursday being closest to normal.
Aviation /18z Saturday through Thursday/...
VFR expected through the taf period as high pressure remains
overhead tonight, then moves east Sunday.
S/SW less than 10 kt this afternoon, becoming light and
variable tonight. S/southeast winds less than 10 kt developing Sun
There is a low chance of MVFR to IFR fog late tonight at
Outlook for 18z Sunday through Thursday...
late Sunday...VFR. S/southeast seabreeze 8-12 kt for coastal
Sunday night-Monday...MVFR/IFR possible in stratus and fog
Sunday night. S/southeast g20 kt Monday afternoon.
Monday night-Tuesday...potential for 6 hr period of S/southeast
g30-40 knots with low level wind shear south-southwest 45-55kt@2kft for coastal terminals.
Could occur during morning push. MVFR/IFR developing in -radz
Mon night and continuing with rain shower Tuesday.
Tuesday night-Wednesday...IFR possibly continues in showers
Tue night...improving to MVFR Wed.
Wednesday night-Thursday...VFR, with iso-sct MVFR with shra.
sub-advsy conds will prevail on the waters into at least Mon night.
The pressure gradient will begin to tighten late Mon night between
high pressure to the east and strengthening low pressure to the
west. Small Craft Advisory conds are expected to develop on Tue, with gale force
winds possible late Tue and Tue night as there is the potential for
a 50-60kt low level jet at 950mb. There is uncertainty with the strength and
track of the low, so wind forecast does not reflect this potential
yet, but have increased the gusts from previous forecast. Will also
mention the gale potential in the severe weather potential statement. Winds begin to subside Tue
night, although the GFS is faster than the ec, so may be bringing
them down a bit too quick. Seas will likely remain above Small Craft Advisory
levels on the ocean waters through Wed night.
no hydrologic problems are expected the next 7 days. Rain with cold
frontal passage late Tuesday should average near 1".