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Area forecast discussion 
National Weather Service Burlington Vermont 
936 PM EDT Sat Mar 20 2010 


Synopsis... 
cooler temperatures are returning to the north country as a cold 
front moves across the region. The front will remain in the 
area through Sunday...with a lot of clouds and a chance for some 
precipitation...especially Sunday afternoon. A low pressure system 
will move northeast from the Ohio Valley Monday...bringing rain 
and perhaps some mountain snow through the first half of the work 
week. 


&& 


Near term /until 6 am Sunday morning/... 
as of 930 PM EDT Saturday...cold front has settled southeastward 
across southern Vermont this evening with bulk of cloud cover 
displaced to the north across northern New York and northern Vermont. All in all...not 
much weather of significance associated with the frontal zone. Mosaic 
composite reflectivity at 0130z continues to indicate narrow band of 
mainly 10-20 dbz echoes near the international border...extending south-southwestward 
into southeastern Ontario. Clouds are generally in the 6-9 kft range...and 
relatively dry planetary boundary layer will generally preclude anything more than a 
few sprinkles or a higher elevation flurry overnight. Have kept 
probability of precipitation at 20 percent or less across northern areas. Temperatures have not 
dropped that substantially to this point...ranging from the middle- 
upper 30s along the international border to 49f at kvsf. Weak low-level cold air advection 
continues overnight and should bring most locations to near 
freezing by sunrise. Winds will continue from the north at 5-10 
miles per hour within the frontal zone. 




&& 


Short term /6 am Sunday morning through Monday night/... 
as of 343 PM EDT Saturday...unsettled period of weather unfolding. 
Have gone with model blend for this period...leaning a bit towards 
the GFS. Aforementioned front will continue to dissipate and 
remnants will attempt to return north as a warm front during 
Sunday. Guidance continues to suggest some lift and upward 
vertical motion with this feature associated with some 
frontogenesis...especially during the afternoon and evening hours. 
Likely probability of precipitation preferred for central and northern areas...and chance probability of precipitation 
south. Ptype an issue should precipitation arrive in the morning...but as 
temperature profiles warm a bit during the day...expect mainly rain 
during the PM/even period. Little if any snow accumulate expected 
during the morning hours. 


Front sags south again Sunday night. Best chances for some rain or 
wet snow showers will be prior to midnight. Somewhat drier air 
attempts to build in across the northern areas late at night...enough to 
shut off any precipitation but not enough to allow for much if any clrng. 
The lull in precipitation is likely to continue into Monday morning...but 
precipitation chances will be increasing during the afternoon and into Monday 
night as we come under influence of low pressure aprchg from Ohio 
Valley. Models all trending further north with track of low and its 
associated precipitation shield...resulting in likely to categorical probability of precipitation for 
later Monday and Monday night. Model soundings indicate temperatures warm 
enough in low/middle levels so that precipitation during this period will be 
mainly rain...although there is potential for wet snow mainly above 
1000 feet which could result in some light slushy accumulations. 
More details as the event nears. 


As for temperatures...it will certainly be colder than we've grown 
accustomed to recently...but temperatures will still be above normal for 
the most part...especially the mins given the extensive cloud 
cover. Have gone close to a mav/met blend on maximum temperatures...and a bit 
above for the mins. 


&& 


Long term /Tuesday through Saturday/... 
as of 343 PM EDT Saturday...rather active period in store for the 
region as low pressure and the combination of several surface fronts 
affect our area. Period will begin with large-scale low pressure 
tracking slowly northeast into the northern middle Atlantic/southern New 
England region Tuesday/Tuesday night with widespread precipitation. While surface 
reflection rather weak...fairly impressive vorticity bundle and 
middle level height falls are associated west/this feature. Thus likely to 
categorical probability of precipitation offered off this morning's guidance certainly 
seems reasonable here...especially given northward trend of surface low track 
in models. Way too early to specify details...but based off mean 
925-850 thermal profiles looks like mainly a light rain event on 
Tuesday... transitioning to a rain/snow mix or a wet snow for 
portions of the region Tuesday night as wet bulb cooling processes 
occur. Could see some wet accumulate across our mountain zones during the 
period...typical during marginally cool early/late season events 
where boundary layer thermal profiles play the greatest role in ptype. 


Thereafter...a series of weak surface ridges and surface fronts will 
traverse the region during Wednesday/Thursday with on and off periods of 
pc/clear skies and/or scattered rain or snow showers. Temperatures should 
remain near seasonal normals until Friday when a more potent 
modified Arctic front sweeps across the area. Models still in 
disagreement on specific timing and degree of Post-frontal 
cooling...and while only scattered light precipitation is expected confidence is 
increasing that a brief return to late winter-like chill will occur 
by later Friday into next weekend. 


&& 


Aviation /02z Sunday through Thursday/... 
through 00z Monday...a cold front continues to linger near the 
Canadian boarder this evening...causing the potential for MVFR 
ceilings in lt rain at the northern taf sites and IFR ceilings in lt snow 
at kslk until 3z. Overall this boundary is relatively dry and 
very slow moving. VFR conditions are expected for much of the prd until 
afternoon when the boundary inches back north with some lt rain and 
MVFR ceilings again at kmss. Generally lt northwest winds will continue 
tonight...becmg vrb and calm at times as the boundary remains 
stationary over the region. 


Outlook 00z Monday through Thursday...the chance of MVFR conditions in 
-ra/snow will continue through Wednesday as a low pressure center moves slowly 
NE along the stationary front...enhancing precipitation across our 
region...especially Tuesday. The low will finally pass to the southeast on 
Wednesday allowing for a return to VFR conditions. 


&& 


Btv watches/warnings/advisories... 
Vermont...none. 
New York...none. 


&& 


$$ 
Synopsis...rjs 
near term...banacos 
short term...rjs 
long term...jmg 
aviation...New Hampshire 

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