Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Albany New York
644 am EDT Sat Apr 18 2015
a cold front push southeast through the region early this
afternoon. Its passage may be accompanied by isolated showers...mainly
north. In its wake winds will become brisk for several hours. This
evening into Sunday evening...high pressure will crest over the
region with fair and dry conditions. A series of systems will
impact the region next week with cool...damp...and unsettled
conditions much of the week.
Near term /through tonight/...
as of 630 am EDT...some fog developed into portions of the
dacks...Lake George Saratoga region...southern Vermont into portions of
the Berks this morning. This fog should be rather shallow and
quickly burn off with sunrise. Otherwise...upstream wave was
approaching with an increase in cloud coverage upstream /few-sct/.
Modified hourly temperatures/dewpts/winds based on observations.
Short wave and associated surface low just to the north of the
Great Lakes was track mainly east with a slight jog to the east-
southeast expected through the day. Moisture remains rather
limited with this system with latest hrrr/hrrrx reflectivity
forecasts suggesting some widely scattered/isolated showers
developing around the noon hour and into the early afternoon
hours. The best potential for some brief wet weather will be north
of Albany and into the southern greens of Vermont /may touch northern
The main issue for the day will be an increase in westerly winds
this afternoon. Momentum Transfer of the higher magnitude winds
suggest we tap into h700 layer where 30+kts resides. While we
should be below Wind Advisory criteria...it will become breezy/windy
at times this afternoon. As for temperatures...given the deep
mixing expected and current temperatures running a couple degrees
warmer...guidance and dry adiabatic decent of those parcels along
with favored locations for downsloping would yield temperatures at
70f or lower 70s for valley locations and 50s for the higher terrain.
Tonight...subsidence along with drier air aloft and surface high
building into the region will result in diminishing winds and any
residual cloud cover. So a clear night expected with lows ranging
from the upper 20s across the dacks to around 40f along the Hudson
River from Albany and point southward.
Short term /Sunday through Tuesday/...
general model suite agreement here with some spread toward the end of
the period...mainly on quantitative precipitation forecast amnts.
Sunday begins with 500hpa ridge axis from Delaware-Maryland-Virginia to Lake Huron...and
surface high ridging S from qb. Result will be widespread subsidence...low
relative humidity...light winds and Brilliant sunshine. Sun evening the 500hpa ridge
will slide offshore along with the surface high. Overnight evolving
upper Great Plains 500hpa cut off shifts east...sharpening the trough/ridge
amplitude and shorting the wavelength and uvm. Surface cyclogen
ensues in the west Ohio Valley and lifts NE into the S Great Lakes Monday. Warm front
trails southeast from Michigan-Virginia convective available potential energy...and lifts toward region sun nt as surface low
organizes on the coast. Result will be rapidly increasing low level surface wind
gradient...increasing low level jets...and moisture influx into region. Rain showers will
develop overnight sun and evolve into a widespread rain into Monday.
The 500hpa cut off over the Great Plains moves little by Tuesday only
reaching Lake Superior. With the surface low over Ontario...the frontal
structure has evolved into an occlusion from Ottawa Valley to coastal low
over S new eng Tuesday morning. Once the occlusion clears the area...dry
slot wraps across region with generally impvg conds. Although
there is some spread in the models on the timing..all have done so
by 18utc Tuesday. As 500hpa short waves are in rotation around base of
cutoff to our northwest...scattered -shra may still occurring in steepening
lapse rate over fca.
Temperatures will be near to slightly below normals during this period with
highs in the upper 50s to middle 60s Sunday...and mainly in the 50s
afterwards. Lows will be in the 30s with 40s Tuesday morning.
Long term /Tuesday night through Friday/...
this period will be dominated by a large vertical low pressure
system centered over Ontario...but impacting much of eastern half
of Canada and NE USA.
While the models differ in timing and placement of the features...the
main story will be 500hpa short waves rotating around the large
cutoff...each dragging a surface front/boundary through the fca.
These features will produce variable clouds...and trigger scattered to at
times broken -shra... maybe some -shsn at hir terrain...however the
activity will be diurnally modulated as strong April sun...and
steep lapse rates will enhance the convective nature of the system
an may even result in some small hail.
As its often with these events...when fca is on southeast quadrant of a
major cut off system...they tend to over do The Dismal conditions
clouds and showers.
Forecast period will feature below normal temperatures with highs mainly
50s...lows in the 30s...vrble clouds...scattered -shra/-shsn. These will
be driven...diurnally...with passing 500hpa short waves and by cdfnts.
Aviation /12z Saturday through Wednesday/...
Appears IFR conditions evolved at kgfl-kpsf overnight where dewpoint
depressions quickly collapsed. This fog should be rather shallow in
nature and quickly dissipate with sunrise.
During the day...frontal boundary will quickly move across the
region. While moisture remains limited with this system...some scattered-
broken VFR ceilings are expected mainly affecting kgfl-kpsf.
Otherwise...westerly winds will increase with gusts over
20kts...then winds shifts to the northwest with even some higher
gusts around 25kts.
The winds and skies will all dissipate this evening as high pressure
settles across the entire region with VFR conditions expected.
Sunday night: high operational impact. Breezy. Likely rain.
Monday: high operational impact. Breezy. Definite rain.
Monday night: high operational impact. Definite rain.
Tuesday: moderate operational impact. Chance of rain showers.
Tuesday night: moderate operational impact. Chance of rain showers.
Wednesday: moderate operational impact. Chance of rain showers.
Wednesday night: moderate operational impact. Chance of rain showers.
Thursday: moderate operational impact. Chance of rain showers.
red flag warning for all of eastern New York...Berkshires and
northwest Connecticut later today...
gusty winds and low relative humidities for southern Vermont...
Extensive coordination overnight along with forecast meteorological
conditions have warranted the upgrade to red flag warnings for
eastern New York...Berkshires and northwest Connecticut. We will
highlight the low relative humidities...snow coverage into the
higher terrain...and gusty winds with a Special Weather Statement
/sps/ for southern Vermont.
Compact wave to the north of the Great Lakes will track east-
southeast today. Moisture associated with this system remains
limited...however...isolated showers are possible mainly to the
north of Albany and into southern Vermont and perhaps touching northern
Berkshires. Thereafter...deep mixing with increasing winds and
dropping relative humidity values yields a combination of fire
weather hazards today. The main impact potential will be during the
For southern Vermont...increase in cloud cover along with marginal
levels for fire weather...snow cover across the higher terrain and
coordination with officials have resulted in a Special Weather
Tonight...winds will subside along with a slow recovery of the
relative humidity values as a surface high builds into the region.
This high remains in control through Sunday with light winds yet dry
conditions with minimum relative humidity values ranging between 20-
no hydrology issues expected through the Monday morning as conditions
will be mainly dry except isolated -shra north tier midday today with a
cold front passage. A widespread soaking rainfall is likely late Sunday night
into Tuesday west/quantitative precipitation forecast on the order of half an inch to an inch.
The National operational hydrologic remote sensing center (nohrsc)
indicates that there is still a few inches of water equivalent in
the snow pack across the southern Adirondacks and northeastern
Berkshire County. Portions of the southern Green Mountains still
have 4 to 9 inches of snow water equivalent.
The general consensus is for around an one inch of rainfall at
this time with the higher totals south of the capital district.
This rainfall combined with rises from ongoing snowmelt north...may
result in within bank rises Monday and Tuesday.
For details on specific area river and lakes...including observed
and forecast river stages and lake elevations...please visit the
advanced hydrologic prediction service /ahps/ graphs on our web-
CT...red flag warning from noon today to 8 PM EDT this evening for
New York...red flag warning from noon today to 8 PM EDT this evening for
Massachusetts...red flag warning from noon today to 8 PM EDT this evening for