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Area forecast discussion 
National Weather Service Buffalo New York 
332 am EDT Thursday Mar 18 2010 


Synopsis... 
high pressure ridging across the lower Great Lakes will continue to 
provide the region with beautiful early Spring weather today and 
Friday...with temperatures both days averaging well above normal. 
A weak cold front will pass across the area during the day Saturday 
before stalling just to our east Saturday night and Sunday. Moisture 
from a southern storm will then surge across our New York state 
during the second half of the weekend with the stalled front helping 
to focus precipitation over our region. 


&& 


Near term /through tonight/... 
07z surface analysis showing high pressure centered over the 
Southern Plains and dominating much of the nation east of The 
Rockies. A weak cold front is draped from the Canadian prairies to 
the Gulf of Saint Lawrence. Short term model guidance is in good 
agreement in dropping this front south into the Saint Lawrence 
valley and northern New England this afternoon and evening in the 
form of a weak backdoor front. This will bring little fanfare to the 
area with nothing more than a period of middle/high clouds this 
afternoon and evening across the north country. From Oswego County 
westward expect skies to remain clear through the period with 
nothing more than some passing thin cirrus level clouds this 
afternoon and tonight. 


00z/18 kbuf sounding again showed the lower troposphere well mixed 
to 850mb. With 850mb temperatures prognosticated to be around +4c today...a degree 
or so milder than yesterday...expect surface temperatures to be a notch 
higher than yesterday. With this in mind...will aim at or above the 
highest MOS guidance with highs reaching the low to middle 60s across 
the lower elevations away from lake influences...with upper 50s to 
around 60 on the hills and middle 50s east of Lake Ontario. 


Strong differential heating will again allow lake breezes to develop 
by afternoon with flow becoming onshore along most of the shoreline 
of lakes Erie and Ontario. For Lake Erie...expect flow to be mainly 
southwest today which will direct cooling into the buf metropolitan area 
again and the immediate Lakeshore down to the PA state line. There 
will be a typical early Spring wide range in temperatures across the buf 
metropolitan area again with downtown in the upper 40s to lower 50s while 
the distant east and southeast suburbs make it into the lower 60s. 
Off Lake Ontario expect southwest winds at the east end of the lake 
to keep the Lakeshore in the upper 40s to lower 50s. Also expect 
flow to veer more northwest along the shoreline from Rochester to 
Oswego during the afternoon in response to a developing lake breeze 
circulation...cooling the shoreline in this area as well. 


&& 


Short term /Friday through Sunday night/... 
our nice early Spring weather will continue on Friday as a 
progressive ridge will cross the upper Ohio Valley and lower Great 
Lakes. 850 mb temperatures of 4/6c should easily support afternoon surface highs 
of 60 to 65 in most areas...although a southwest wind off the icy 
waters of Lake Erie will produce a noticeable chill in downtown 
Buffalo where readings will be held to the lower 50s. Temperatures will 
also be held down a bit across the northern sections of Jefferson 
County. 


A weak cold front will slowly ease southwards across southern 
Ontario Friday night while middle and upper level ridginess will hang 
on across our forecast area. This will keep fair weather in place 
through Friday night but clouds will gradually be on the increase 
from the northwest. 


While this front is expected to cross the forecast area on 
Saturday...this will be an Ana front with the precipitation found in its 
wake. The deepest moisture will be found upstream from the 
front...and that is also where weak jet dynamics will be found. As a 
result will increase the cloud coverage across the region on 
Saturday but will keep mainly dry with only slight chance probability of precipitation near the 
lakes. Saturday will still be a mild middle March day with 850 mb temperatures of 
3/4c helping to produce surface highs ranging from the low 50s along the 
Lake Shores to the middle 60s in the Genesee Valley and Finger Lakes 
regions. 


The deeper moisture in the wake of the surface front will start to move 
across our region during the course of Saturday night. As 
mentioned...there will be some weak jet dynamics for this moisture 
to interact with so will use chance probability of precipitation across all of the region by 
late Saturday night. Any rain showers that do occur should be light. 


On Sunday...an anomalously deep 500 mb cut off over the lower 
Mississippi Valley will lift its associated surface reflection up the 
Ohio Valley. Moisture will surge northwards in advance of the surface 
low with an upper level diffluent flow becoming established over 
Ohio and much of Pennsylvania. Further to the north over our 
region...a stalled frontal boundary will be in the vicinity of 
kbfd-kith-kalb. A steepening thermal gradient to the north of this 
front should focus the increasing moisture form the southern storm 
so that showers over our region become more widespread. Will use 
likely probability of precipitation for showers regionwide as a result. 


Some steadier rain can be expected Sunday night as the surface low is 
forecast to move east across Maryland. While low and middle level 
moisture will continue to increase our region Sunday night and 
Monday...the region of diffluent flow will lift to the north. The 
00z runs of the GFS and European model (ecmwf) are at odds over the timing of the 
steadier rain...with the GFS suggesting that the steadier precipitation is 
Sunday night and early Monday. The European model (ecmwf) is about 8 hours later in 
its timing. Will lean towards the GFS for now as it is closer to our 
original continuity. 


In either case...both models are not nearly as aggressive with the 
colder air moving into the region as the surface low is just too far 
north. 850 mb temperatures Sunday night are now forecast to remain above 0c...so 
will make a big change to continuity and remove mention of snow. 
This will also mean that over mins for Sunday night will be raised 
by 5-10 degree from continuity. 


&& 


Long term /Monday through Wednesday/... 
after a spell of seasonably mild weather...the bulk of this period 
will feature below normal temperatures. For those itching for Spring 
though...fear not as a noticeable warm up is anticipated for the 
middle of next week. 


Troffiness over eastern Canada and the lower Great Lakes Monday and 
Tuesday will lift out across the Canadian Maritimes by Tuesday 
night. A broad low amplityude ridge will then become established in 
the wake of the trough on Wednesday with the GFS and European model (ecmwf) mean 850 mb 
temperature being found in the vicinity of 2/4c. This is not quite as warm as 
previous model runs...but still suggests a quick rebound to pleasant 
early Spring temperatures for the middle of next week. Some 
details... 


Monday should still be a rainy day across the forecast area...as the 
closed low to our south will still be close enough to produce fairly 
widespread showers across the region. If the European model (ecmwf) is closer to 
reality...then Monday will be one of those days where a cold rain 
will fall all day. The GFS is suggesting that the cold rain will be 
mixed with a little wet snow...and that the precipitation will taper off from 
the north and west during the course of the day. Again...will lean 
more towards the GFS as it is closer to yesterdays continuity. 


Gradual clearing can be expecetd Monday night...although the slower 
European model (ecmwf) still shows some lingering showers. 


Ridging will start to build in behind the departing trough Tuesday 
and Tuesday night...so while temperatures will still be on the chilly side 
of normal...conditions should improve. 


The nicest day of the this extended period can then be expected on 
Wednesday with a 500 mb ridge well established over the Ohio Valley and 
warm advection well underway regionwide. 


&& 


Aviation /08z Thursday through Monday/... 
high confidence in VFR conditions prevailing for the 06z taf cycle. 
High pressure surface and aloft centered over the middle section of the 
nation will continue to extend ridging into the Ohio Valley and 
lower lakes region. This will provide mainly clear skies today with 
nothing more than a few thin cirrus dropping down from the north 
during the afternoon. The cirrus will thicken a little across the 
north country including kart later today and tonight. 


Away from the lakes expect light and variable winds to become west 
around 10 knots today...with lake breezes allowing winds to become 
onshore near lakes Erie and Ontario. 


Outlook... 
Friday and Saturday...VFR. 
Sunday...VFR/MVFR with rain showers developing. 
Sunday night and Monday...MVFR/IFR with rain showers changing to 
snow showers. 


&& 


Marine... 
no marine flags are expected through at least the upcoming weekend 
as relatively weak scf pressure graidents will be in place. Both 
wind and wave conditions are expected to remain below Small Craft 
Advisory criteria. 


&& 


Fire weather... 
abundant sunshine combined with warm temperatures and low relative 
humidity each afternoon will continue to allow fine fuels to cure 
and dry. Even after the wet weather last weekend...fine fuels are 
already drying out...with the Iroquois NWR RAWS site recording a 
minimum 10 hour fuel moisture of 8 percent Tuesday and Wednesday 
afternoon. This will bring an increase in fire danger through the 
rest of the week. Relative humidity is expected to bottom out in 
the 20 to 30 percent range this afternoon...with the lowest relative humidity 
across higher terrain away from lake influences. Winds will be 
relatively light however at less than 15 miles per hour through Friday... 
keeping conditions under red flag criteria. Stronger winds are 
expected this weekend...however they will be accompanied by higher 
relative humidity. 


&& 


Buf watches/warnings/advisories... 
New York...none. 
Marine...none. 


&& 


$$ 


Synopsis...rsh 
near term...Hitchcock 
short term...rsh 
long term...rsh 
aviation...Hitchcock 
marine...rsh 
fire weather...Hitchcock 

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