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fxus61 kbgm 212351 
afdbgm 


Area forecast discussion 
National Weather Service Binghamton New York 
751 PM EDT sun Mar 21 2010 


Synopsis... 
our mild sunny weather will come to an end today, as a large 
storm system moves out of Arkansas and spreads rain into New York 
and Pennsylvania Monday and Tuesday. 


&& 


Near term /through Monday/... 
still some clouds over the northern zones near Lake Ontario in New York 
from a short wave that moved through this morning with showers and a 
stalled frontal boundary. This is helping create a 20 degree 
temperature differential across the area. Clouds have diminished 
over the southern tier and NE PA on the down side of an upper level 
ridge. Increased sunshine helping to bump up temperatures in the 60s 
and lower relative humidity. Scranton was reading 66 at noon while Syracuse was 
only 48 degrees. Models have continued to increase surface dew 
points too fast in advance of the next system and so adjusts were 
made to lower them. 


Clouds will increase overnight with warm advection and isentropic 
lift ahead of the next system. By morning chance of light rain 
moving into NE PA and the southern tier New York. Clouds will help keep 
overnight temperatures warmer than last night. Dew points should be 
higher and winds will remain light. 


&& 


Short term /Monday night through Wednesday/... 
a large slow moving stacked storm centered over Arkansas will 
track east-northeast during the short term. Rain on the NE side of the storm 
will move into the County Warning Area around sunrise Monday. Once it starts the 
rain will become steadier Monday then continue into Tuesday. An 
area of heavy rain is possible late afternoon Monday into the evening. 
A deep south flow of warm moist air up the East Coast moves in 
midday. The rain will slowly taper off Monday overnight as the 
best forcing moves to eastern New York. 


The stacked low passes to the south across the middle Atlantic. A 
dry slot may work into NE PA Tuesday while a longer fetch across 
New England should mean less rainfall late Monday night to 
Tuesday. Low GOES off Delaware-Maryland-Virginia late Tuesday to Cape Cod Tuesday 
night. Low level flow shifts to northwest pulling in colder air. Surface 
temperatures go to 30s while 850 mb temperatures go below 0c. Put in a mix of 
rain and snow Tuesday overnight. 


As high pressure slowly builds in Wednesday with drier air 
increasing sunshine and slightly warmer high temperatures than Tuesday 
despite cold air advection. 


&& 


Long term /Wednesday night through Sunday/... 
period will start with northwesterly upper-level flow gradually 
becoming southwesterly by Thursday afternoon as the next wave begins 
digging just south of Hudson Bay. Warm air advection ahead if this 
feature combined with the likelihood of much of the the County Warning Area residing 
in the warm sector ahead of the main cold front will allow temperatures to 
warm well into the upper 40s to lower 50s across much of the area. 
Models do maintain some disagreement with regards to the overall 
surface reflection position with the European model (ecmwf) maintaining a further 
northward track as the surface low tracks east across central 
Ontario/Quebec. Meanwhile...GFS is a little further south while the 
Gem is the in between solution. That said...GFS shows precipitation 
beginning to work into the area Thursday night/early Friday with European model (ecmwf) 
maintaining a dry forecast. For now will follow the drier European model (ecmwf) 
solution with appears favorable with adjacent offices and HPC. Main 
attention then quickly shifts to a strong cold front that is 
expected to plow through the area by Friday morning. Models have been 
advertising this scenario for the past several days and everything 
appears to be coming together for a significant cool down by the 
start of the upcoming weekend. Strong cold air advection following 
the passage of this feature will send 925 mb temperatures into the -4 to 
-8c range...which suggests high temperatures will struggle to make it out 
of the low to middle 30s Friday afternoon. With 850 mb temperatures expected to be 
in the -12 to -15c range across the area...lake effect snow showers 
appear possible as lake surface temperatures currently reside a couple of 
degrees above zero. Cold air will be shortlived as next disturbance 
will begin moving towards the area by late in the weekend. Warm air 
advection ahead of this feature will allow temperatures to rebound into the 
upper 40s to lower 50s by the sun. 


&& 


Aviation /00z Monday through Friday/... 
VFR conditions to dominate at all terminals through the overnight 
hours with just some middle/upper clouds expected to move across the 
area. Winds should remain light and northerly across the all New York 
terminals with southerly winds expected at avp which is south of 
a frontal boundary. Main focus of concern continues to be a large 
upper low located across the deep south at this time. Moisture in association 
with this feature will begin working north towards the area 
overnight with precipitation expected to begin overspreading the area 
from south to north as the morning progresses. Thus can expect a 
categorical decrease to MVFR conditions area wide with some 
temporary IFR ceilings/visibilities during the late afternoon across avp/bgm 
where rain will likely be the heaviest. Strong winds aloft will 
also move into the area during this time which may lead to some 
low level wind shear concerns. Will pass concerns off to middle crew for now. 


Outlook 
Monday night and Tuesday...IFR/MVFR in rain. 
Wednesday/Wednesday night...MVFR showers improving to VFR late Wednesday/early Thursday. 
Thursday...VFR. MVFR possible Thursday night in showers. 
Friday...VFR. 


&& 


Fire weather... 
another mild day further drying the fine fuels. Relative 
humidities have fallen to between 30 and 50 percent this 
afternoon. The good news is surface winds will be light at under 10 
miles per hour today. 


Starting Monday rain moves in so fire threat low into at least 
Wednesday. Cooler at the end of the week so threat increasing from 
Monday and Tuesday but lower than this weekend. 


&& 


Hydrology... 
may need to issue a Flood Watch for late Monday into Wednesday for 
the potential for river and flash flooding. At least 20 hours away 
for what looks like a minor flood event so will not issue a 
watch this afternoon. The New River forecasts for the Delaware 
have Walton on the West Branch going over flood stage Monday 
overnight. On the Susquehanna rising stages to 12z Wednesday where 
Conklin and Waverly/Sayre just below flood stage. Ensemble model 
runs also bring the Susquehanna River at Unadilla and Bainbridge 
to around flood stage. 


With light rain moving in around sunrise will probably hold off 
on a Flood Watch until the rainmaker in the central US gets 
closer. Does not look like any problems until at least Monday 
afternoon. Flash flood guidance between 1 and 2 inches. Expected 
rainfall amounts of 1 to 1.5 inches across the entire County Warning Area with the 
highest amounts in NE PA and Sullivan New York. 


&& 


Bgm watches/warnings/advisories... 
PA...none. 
New York...none. 


&& 


$$ 
Synopsis...djp 
near term...bmw/tac 
short term...tac 
long term...cmg 
aviation...cmg 
fire weather... 
hydrology... 

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