349 
fxus61 kaly 201445 
afdaly 


Area forecast discussion 
National Weather Service Albany New York 
1040 am EDT Sat Mar 20 2010 


Synopsis... 
another unseasonably warm day today. A cold front across the 
eastern Great Lakes early this morning will move southeast across 
the region today...very limited moisture is associated with the 
boundary so only an increase in clouds is expected. This boundary 
is forecast to stall just to our south across the New York 
metropolitan area tonight. An area of low pressure will move 
eastward along this boundary reaching the middle Atlantic region 
early next week. With the boundary in the vicinity and the low 
approaching there will be chances for precipitation...especially 
early next week. 


&& 


Near term /until 6 PM this evening/... 
as of 1030 am...cold front was progressing across the western Mohawk 
Valley and dacks with most of the clouds Post frontal. With a rapid 
diurnal rise observed this morning...have adjusted temperatures accordingly 
including our 12z sounding suggesting mixing potential near 800mb 
/yields middle 60s for the valley locations/. Did lower temperatures several 
degrees across the dacks with frontal passage and associated increase in cloud 
cover toward this early afternoon. Also...not much precipitation noted 
upstream and have removed the slight chance probability of precipitation for the dacks late 
today. Remainder of the forecast in excellent shape as 12z guidance 
is now arriving. 


Previous discussion... 
Spring starts this afternoon at 1:32 PM. 


A cold front across the eastern Great Lakes will move southeast 
across the area today. Moisture is very limited with the boundary 
and upper level support will remain well to the north. So only an 
increase in clouds is expected. 


It will be unseasonable warm again today across most of the 
forecast area....with temperatures warming into the 60s with 
around 70 degrees in the middle Hudson Valley. Readings across the 
southern Adirondacks will be cooler but continued above normal 
mainly in the 50s as the boundary moves across that area this 
morning. 


The record high temperature for Albany for March 20th is 74 degrees 
set back in 1903. 


&& 


Short term /6 PM this evening through Monday/... 
the models are in good agreement that the cold front will stall 
just to our south across the New York metropolitan area tonight. In the 
meantime...the longwave trough digs across the plains. An upper low 
will cut off over Texas/OK by this evening. A surface low will develop 
in response. This system becomes nearly vertically stacked and 
tracks east-northeast along the stalled boundary. The storm is 
expected reach the Ohio Valley/middle Atlantic region by Monday 
evening. Ridging will be induced across the northeast as the low 
approaches. As for chances for precipitation...the models are not in 
good agreement with the timing and placement into Monday. The 
precipitation through this time frame will be light with the 
steadier and more widespread precipitation moving in Monday 
afternoon/evening as the low moves closer to the region. Have mainly 
slight chance for tonight and mainly chance probability of precipitation for Sunday into 
Monday. There will be chances for snow as temperatures drop at night 
across portions of the southern Adirondacks and southern Green 
Mountains...otherwise expecting rain. 


&& 


Long term /Monday night through Friday/... 
the long term begins wet and unsettled...as the cutoff low over the 
middle Atlantic region slowly moves to the east/NE into Tuesday night. The 
latest global ensembles show a low level h850 easterly /-u 
component/ wind anomaly 2-3 Standard deviations greater than normal 
over much of New York and northern PA Monday night into Tuesday. Good qg lift 
occurs north of the main surface wave tapping into Atlantic moisture. 
The precipitable water anomalies are 1-2 Standard deviations above 
normal. We increased the probability of precipitation to categorical values from the Hudson 
River valley east late Monday night through Tuesday morning. 


The GFS/NAM isn/T showing too much in the way of snow or mixed precipitation 
over the southern Adirondack region Monday night into Tuesday morning. 
However...enough dynamic cooling from the potentially moderate-heavy precipitation 
may cool the column down enough for a few inches of wet snow. The 
nwp has a hard time handling this /for example the 13-14 March 
event/. We keep the precipitation as a snow/rain mix between 33-35f...and snow 
below 33f. Overall...this looks like a soaking rain event /which is 
much needed from the Mohawk Valley/capital region northward in the 
upper Hudson Valley and Lake George region...where it has been very 
dry this month. Some locations north and east of kalb may transition 
to some snow showers Tuesday night...as much colder air filters in 
aloft...with the stacked low passing south of Cape Cod. 


Wednesday...a short wave ridge quickly builds in aloft...with a 
quiet day and temperatures rebounding back to slightly above normal levels 
in the u40s to u50s. However...a secondary cold front may bring some 
scattered rain or snow showers overnight. 


Thursday into Friday...the guidance diverges on the timing of the 
next strong cold front. We leaned closer the European model (ecmwf) and the HPC 
graphics with a frontal passage during the day on Friday. We kept a 
chance of showers in for all locations. It may be a mix of rain or 
snow showers over the southern Adirondacks...and southern Green Mountains late in 
the day. The cold air advection is impressive with the front...as a 
cold Canadian air mass builds in Friday night. H850 temperatures may fall 
close to -10c in the capital region...and -5c over the middle Hudson 
Valley. Maximum temperatures to open next weekend may actually be a shade below 
normal in the 40s in the valleys...and 30s over the mountains 


&& 


Aviation /12z Saturday through Wednesday/... 
a cold front will slowly move southeast across the region from the 
Saint Lawrence River valley today. It will become stationary over 
southern New York and southern New England Saturday night. VFR conditions will 
prevail the next 24 hours. 


The cold front is moisture starved with only some middle and high 
clouds associated with the passage in the afternoon. There is the 
potential of a high stratus deck moving into kgfl late in the day. 
Middle and high clouds will persist from kalb south to kpou into the 
early evening. Some moisture may over run the boundary overnight 
causing a cloud deck in the 4-8 kft above ground level range to form. We placed 
some vcsh groups in from kalb northward to kgfl after 06z/21. 


The winds will be light and variable ahead of the front this 
morning. They will shift from the southwest to west northwest with 
the passage in the afternoon at around 10 kts. Some gusts based on 
the NAM BUFKIT profiles could approach 20 kts...especially at kalb 
where they will be in the 20-25 knots range. The winds will decrease 
in the early evening with high pressure attempting to ridge in from 
Quebec...as the winds will be around 5 kts from the north or 
northwest. 


Outlook... 
Sat nt...VFR. Slght chance -shras. 
Sun...VFR/MVFR...chc -shras. 
Mon-Tue...MVFR/IFR ceilings and visibilities with periods of rain. 
Wednesday...VFR...no sig weather. 


&& 


Fire weather... 
another dry day with unseasonably warm temperatures. Minimums 
relative humidity levels of 30 to 40 percent are expected this 
afternoon generally east of the Hudson Valley...with values to 40 to 
50 percent to the west. Relative humidity values are expected to 
recover to near 100 percent tonight. 


A cold front across the eastern Great Lakes early this morning 
will move southeast across the region today...very limited 
moisture is associated with the boundary so only an increase in 
clouds is expected. This boundary is forecast to stall just to our 
south across the New York metropolitan area tonight. An area of 
low pressure will move eastward along this boundary reaching the 
middle Atlantic region early next week. With the boundary in the 
vicinity and the low approaching there will be chances for 
precipitation...especially early next week. 


&& 


Hydrology... 
above normal temperatures will last one more day....and dry weather 
will persist into the latter half of the weekend. Diurnal snow melt 
will produce minor rises on streams in the Adirondacks...Catskills... 
Berkshires...southern Vermont...and other areas where snow remains. 
There is still 4 to 10 inches of water in the snowpack over areas of 
the Adirondacks...Catskills...southern Green Mountains...and 
Berkshires. 


A cutoff low will move into the middle Atlantic region Monday and 
Monday night. This storm has the potential to bring three quarters 
of an inch to an inch and a half of quantitative precipitation forecast to the Hydro service area 
late Sunday through Tuesday. The higher totals right now look to be 
over the lower Catskills...middle Hudson Valley...and Litchfield 
Hills. Some wet snow may occur north of the Mohawk River 
valley...and over the southern Green Mountains. The combination of snow 
melt...additional runoff...and above normal flows...especially in 
the Housatonic basin...and several basins in the Catskills...may 
cause main Stem river points in these locations to reach at least 
bank full. 


Please refer to the winter/Spring flood outlook /albesfaly/ 
for more details on the potential for Spring flooding. 


For details on specific area rivers and lakes...including 
observed and forecast river stages and lake elevations... 
please visit the advanced hydrologic prediction service 
/ahps/ graphs on our website. 


&& 


Aly watches/warnings/advisories... 
CT...none. 
New York...none. 
Massachusetts...none. 
Vermont...none. 


&& 


$$ 
Synopsis...iaa 
near term...bgm/iaa 
short term...iaa 
long term...wasula 
aviation...wasula 
fire weather...iaa 
hydrology...iaa/wasula 


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