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Area Forecast Discussion (AFD)

Issued by Binghamton, NY (BGM)

FXUS61 KBGM 221922

National Weather Service Binghamton NY
322 PM EDT Mon Apr 22 2019

A slow-moving low pressure system off the Mid-Atlantic coast
will move northward toward the Gulf of Maine tonight and
Tuesday. High pressure briefly builds over the region tonight.
An area of low pressure will track eastward across the Great 
Lakes region on Tuesday before passing to our north Tuesday
night and Wednesday. The next chance for showers arrives Tuesday
afternoon and continues into Tuesday night when a cold front 
passes through. High pressure builds back in to the region
Wednesday night and Thursday


Mid afternoon surface analysis shows a 1013 mb low positioned 
several hundred miles east of NJ and south of Cape Cod. The western 
fringe of the wrap-around clouds and showers has made it into the 
western Catskills and Poconos this afternoon. These showers in our 
far eastern zones will generally be limited in coverage and 
intensity through this evening.

A weak surface ridge that is currently over the eastern Great Lakes 
and OH Valley will progress eastward into the region tonight. Light 
winds and mostly clear skies west of I-81 will support good 
radiational cooling conditions tonight. Accordingly, temperatures 
should quickly fall after sunset followed by the development of 
patchy radiational fog late tonight into early Wednesday morning. 
With the surface high moving right over C NY, fog is favored in the 
Finger Lakes and nearby river valleys.

A cold front will approach from the Great Lakes region on Tuesday. 
CAMs support the development of showers along a pre-frontal trough 
during peak afternoon heating in our western zones in CNY. This 
activity will then progress eastward across the area late in the 
day. Additional showers are likely with the cold front Tuesday 

Despite strong diurnal heating and relatively steep mid-level 
lapse rates (7-7.5 C/km in the 700-500 mb layer), a capping 
inversion in place, limited moisture in the boundary layer, and the 
better source of deeper lift with the front remaining to our 
west look to limit the potential for deeper convection to be 
sustained during the afternoon and evening. Accordingly, PoPs 
(showers) were generally limited to 30-50 percent and 
thunderstorms to 20 percent until the front arrives in the 
evening. Rain chances end from west to east late Tuesday night 
behind the cold front.


Main concerns in the short term are focused on the exiting rain
showers associated with the most recent frontal passage 
Wednesday morning, then quiet weather with gradually warming 
temperatures into Thursday.

Stacked low pressure system moving east over northern New England 
Wednesday morning will still be able to wrap enough moisture around 
the back side to produce a few lingering light rain showers across 
central NY through late Wed morning. Additional rainfall amounts 
should be less than a tenth of an inch. 

Cold air advecting in from the n/nw behind the system on Wed will 
keep temperatures se of Lake Ontario in the lower to maybe mid 50s. 
Areas from the NY/PA border south will likely warm into the lower to 
mid 60s.

Heights aloft will rise Wed night and an area of high pressure at 
the surface will move in from the west going into Thursday. Should 
be plenty of sun by Thursday afternoon with light sw winds and 
temperatures into the mid to upper 60s.


The pattern becomes more active and wet starting Thursday night
as the upper ridge axis slides to the east along with the wedge
of drier air. An upper trough will dig into the upper Midwest 
during this time as a surface response develops over the Ohio 
Valley. The negatively tilted upper trough will be able to tap 
into a very moist, almost tropical, air mass from the Gulf of 
Mexico and produce a period of potentially heavy rain. The 
surface low track is still a bit uncertain, but most of the 
guidance moves it east through either PA or NY. The bulk of the 
rain is expected to fall just north/nw of the sfc low, so the 
track will play a very important factor where the heaviest rain 
will eventually end up. This system looks to be fairly 
progressive and mostly out of the area by Friday night/Sat 
morning. May see a brief break in the action Saturday night 
before the next fast- moving system rides through on 
Sunday...although this may change given that the pattern becomes
quasi-zonal with multiple waves tracking east along various 
paths that do not appear to be well- defined or with much model 

Afternoon temperatures remain mild through the weekend with highs in 
the 60s...but overnight lows might be on the cool side with 
temperatures dipping into the upper 30s and 40s.


Through sunset...  Stratus continues to erode across CNY this 
afternoon. The last of stratus was over the Finger Lakes region,
keeping CIGs at KITH and KSYR in MVFR range At 18Z. Low clouds 
should quickly scatter out at KSYR before 19Z but it may take 
until 19-20Z to improve to VFR at KITH. Otherwise, VFR and N to 
NW winds generally 6-12 kt thru sunset. 

Tonight...Winds become light and variable after sunset this 
evening. Potential for fog development overnight, particularly 
in the river/lake valleys and in CNY (where the pressure 
gradient is weakest under the surface high). The greatest 
support for fog development from the guidance is at KITH, 
followed by KELM and KBGM. Confidence was high enough with the 
18Z TAFs to go with IFR restrictions in the early morning hours 
at these three sites. There is some support for patchy dense fog
with visibility decreasing to 1/2 SM or less at these sites.

Tuesday and Tuesday evening...Strengthening southerly flow and 
a deepening mixed layer should allow for a quicker dissipation 
of any leftover stratus during the morning Tuesday compared to 
today. Accordingly, mainly VFR is expected after 14-15Z Tuesday.
S winds increase to 8-14 kt w/ occasional gusts near 20 kt by 
the afternoon. Chances for showers increase from west to east 
ahead of a cold front late in the afternoon. Coverage should be 
somewhat limit during this time. Better chances for showers 
during the evening with the approach of the front. An isolated 
thunderstorm is possible as well. Brief visibility restrictions 
possible with heavier showers and storms.

Tuesday night...A wind shift out of the W can be expected in 
wake of fropa overnight. Wind speeds are forecast to be in the 
6-12 kt range. Low clouds streaming off the lakes may result in
a period MVFR CIGs overnight.


Wednesday... MVFR stratocu should gradually break up from south
to north during the afternoon. 

Wednesday night through Thursday... VFR expected.

Thursday night into Friday... The next round of rain looks to
arrive late Thursday night and continue through at least midday.
Sub-VFR possible.

Friday night and Saturday... Predominately VFR.