Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Binghamton New York
700 am EDT Wednesday Oct 22 2014
a large moist upper low will very slowly drift up the middle Atlantic
coast to New England over the course of the next few days. Our
region will be stuck within its reach now through Friday...with
stubborn clouds...cool air...and periods of rain.
Near term /through tonight/...
655 am update...
initial wave of showers-sprinkles is now dropping from western
Catskills across twin tiers/nepa. Trend in high res models and
latest operational models is for a relative lull to occur in the
wake of this wave...before next batch arrives from east late today
into tonight. Forecast adjusted accordingly. Still solid cloud
cover which some may consider dreary...along with patchy drizzle
this morning...but very little rain for a good chunk of the day.
very amplified digging trough has now cut off an upper low...the
center of which is descending upon Virginia...and in response
cyclogenesis is occurring at the surface offshore from Chesapeake
Bay. The surface and upper lows become stacked the next 24
hours...which will halt movement of both...leaving US stuck in the
moist and cool northeast quadrant of the large system for a long
Through today...in addition to a solid overcast sky...waves of
showers will continue to pepper across the area...but best
chances will be east of I-81. To the west...though gloomy...much
of the day will be dry with only a few sprinkles or light showers.
Moisture today will be fairly shallow and thus rain amounts quite
light...most places only one to two tenths of an inch...with even
lighter amounts towards New York thruway corridor.
Then tonight...some deeper moisture arrives. Anomalously strong
easterly component of 850mb wind /as in 3 to 5 Standard deviations
over New England by 12z Thursday/ will further inject Atlantic moisture
into the system. Thankfully with our cool and fairly stable
column...precipitable water values will struggle into increase
to range of three-quarters of an inch to almost an inch by 12z
Thursday. West of I-81...rain amounts tonight will generally just
be a tenth to quarter inch...but to the east and especially
towards Catskills...quarter to half inch of rainfall easily
attainable through tonight with more on the way. By 12z
Thursday...the footprint of this system will be very
expansive...with a train of moisture extending from Cuba to
Bermuda...northward to Nova Scotia...then coiled back across New
England and down the northern Appalachians.
Given all of this moisture and cloudiness...very narrow diurnal
range today and tonight. Upper 40s to middle 50s for highs...lower to
middle 40s for lows.
Short term /Thursday through Friday night/...
345 am update...
strong easterly 850mb jet Thursday morning will reside across New
England...reaching a ways into our region. We should thus still
see plenty of showers in our western Catskills...shifting towards
upper Susquehanna to western Mohawk Valley zones with time. In
regards to areal average quantitative precipitation forecast...expecting another third to half
inch or so of rainfall in those areas on Thursday alone...tenth to
quarter inch farther south and west. As Thursday
progresses...easterly 850mb jet backs with increasingly northerly
component...and in fact even north- northwest by 12z Friday. The
Atlantic moisture will have to take more of a circuitous Route as
time marches on...with increasingly Continental component at lower
levels. So while showers will still continue...actual rain amounts
should lessen late Thursday through Thursday night.
By Friday...GFS and to lesser degree European model (ecmwf) start to let go of the
area...but NAM is slower with exit of upper low and so has
vorticity spoke pivot through the area with more showers. At this
time I have elected for 40-50 probability of precipitation across New York thruway corridor but
only low chance to slight chance twin tiers southward.
Dampness-cloudiness will continue suppress diurnal range for
temperatures...generally lower 40s by night and upper 40s-lower
50s Thursday /mainly 50s Friday/.
As for rainfall totals for this long slog of an event...from today
/Wednesday/ through Friday we have areal averages from several
tenths of an inch in central southern tier New York-Wyoming Valley
PA...to between half inch and one inch or so in western
Catskills-New York thruway corridor-Ithaca-Cortland-Owego-Binghamton-
Montrose-Honesdale-Milford. Spread out over so much time...we do
not at all anticipate any flood-type issues.
Long term /Saturday through Tuesday/...
2 PM update...
500 mb low will be spinning off of the Cape Cod coast at the start of
the extended. This will keep light precipitation in across the area before slowly
winding down by the end of the week. Next system will appch the northern
zones Sat into Sat night with perhaps an isolated shower. After this WV
mvs east, hipres builds in late in the weekend.
Temperatures expected to moderate after closed low ejects into the Canadian
Maritimes Friday night. For the weekend expect highs to be above normal
values as high builds in.
Aviation /12z Wednesday through Sunday/...
a cutoff low over the middle Atlantic region will gradually lift
northeast during the next couple of days and keep the weather
unsettled. Overall...widespread IFR/MVFR expeceted through the forecast period. At
rme...suggestions that brief periods of VFR will be possible due to
slightly drier low level air and downsloping due to NE winds. Later
today expect IFR/MVFR to become re-established. Elsewhere over central
New York...conditions frequently below at mins this morning before potnl
imprvmnt to MVFR later this morning and afternoon. At avp...MVFR expeceted to
prevail. Best chance for -shra appears to be at bgm and avp early
this morning...with -shra becmg more wdpsrd by early evening as
enhanced moisture moves in from the east. North-northeast winds 5-10 knots becoming
nearly 10-15 kts today and north-northwest 10-20 kts tonight.
Wednesday night through Friday...widespread restrictions in lower
cigs/-shra. High confidence of MVFR...low-moderate confidence in
IFR at times.
Sat...becoming VFR though potential exists for MVFR across