Area forecast discussion 
National Weather Service Binghamton New York 
1013 am EDT Wednesday may 22 2013 


Synopsis... 
a warm and humid airmass will remain over the region through 
tonight. Scattered showers and thunderstorms are possible through 
this period along with warm temperatures. A cold front will 
approach the region on Thursday. This system will bring a better 
chance for showers and thunderstorms through Friday morning. 


&& 


Near term /until 6 PM this evening/... 
1010 am update... 
busy weather day shaping up for the region as chances for renewed 
convection and severe weather development appear likely as the late 
morning/afternoon hours progress. First things first however with 
middle-morning radar imagery showing weak showers currently moving 
through the central southern tier and Finger Lakes on the heels of 
a weak shortwave trough currently moving from western PA into 
western New York. So far this activity has behaved but attention remains 
focused on another area of shortwave energy which now resides across 
eastern Kentucky and southern Ohio. With time today...this feature will 
continue lifting northeast where it will encounter an increasingly 
unstable airmass as temperatures warm well into the upper 70s and lower 
80s later today. 


Comparing today/S setup to yesterday/S...the one thing that is 
immediately apparent is that the upper-level wind field is more 
supportive of convective development as an anticyclonically curved 
jet strengthens to our north in increasing confluent flow aloft. As a 
result...much of upstate New York and northern PA will be placed under 
the favorable right entrance region which will enhance upper-level 
divergence across the region. This combined with increasing lift 
arriving with the previously mentioned Ohio Valley shortwave should 
provide plenty of middle/upper support for convective development. 
Shifting closer to the surface...latest 13z subjective hand analysis 
shows a leeside trough extending south from the Central Lake plain 
south through central PA. Further to the north...a lingering 
stationary front remains positioned across northern New York just north 
of the County Warning Area which could serve as an additional focus for 
development later today. 


Summing everything up and considering that the 0-6 km bulk shear 
vectors are forecast to increase to near 40-45 kts later 
today along with unidirectional tropospheric flow...isolated 
splitting supercells cannot be ruled out. Quick look at both the 
12z buf and pit soundings still show nearly dry-adiabatic middle- 
level lapse rates suggesting elevated mixed layer air still 
resides across the region. Latest Storm Prediction Center day 1 outlook maintains a 
slight risk County Warning Area wide with a 30% hail and wind risk. The other 
concern remains heavy rain potential as blended tpw satellite 
graphics continue to show an abnormally moist airmass in place 
with precipitable water values approaching 1.50 inches. Obviously we/ll have to 
watch things as they unfold as heavy rainfall from last night/S 
convection on top of additional rains today may warrant a quick 
Flash Flood Watch for portions of the lake plain and northern 
Finger Lakes region. 


430 am update... showers and thunderstorms continue across the western cats and 
the southern tier as boundaries lurk in the vicinity. Very slight waves riding 
up in southwesterly flow are acting to spark off convection and may continue 
to do so at random tonight. Warm front appears to be located in the far 
northern zones though it is a little uncertain on how far north this 
feature will lift through the day. As it stands now, most of the County Warning Area 
will be clearly in the warm sector along with strengthening winds 
aloft. 


With temperatures into the 80s once again and dewpoints into the 60s, convective available potential energy will 
average around 1000 j/kg give or take. Strong WV at 500 mb forecast to appch from 
the west toward 00z this evng, though any subtle feature can ripple through at 
anytime. Thus, have started probability of precipitation off this morning as scattered and as WV 
approaches and heating commences have gone closer to likely after 21z across northern zones 
in vicinity of warm front. Given what happened yda, potential certainly 
exists for severe weather as wind fields strengthen. 


Given the uncertainty of development will hold off on Flash Flood Watch 
for now and allow day shift to put up a short-fused watch once area 
becomes more clear. As it stands now, rainfall totals of 2-4 inches 
occurred in a short period of time yesterday evening across southern Onondaga, central 
Madison and southern Oneida counties and these will be the areas to watch. 


&& 


Short term /6 PM this evening through Friday/... 
430 am update... 
tonight will feature ul low ejecting east into the upper Midwest. Strong 
srly flow will pump moisture into the eastern half of the country with 
40mm precipitable water values poised to enter into the Tennessee Valley at this time. Expect 
this to mv nwrd into the area tonight and with ul system appchg the 
central Great Lakes by morning and ridge gradually starting to break 
down, will likely see increases in probability of precipitation by 12z Thursday. Overnight lows tonight 
expected to remain in the 60s under moist airmass. 


By 00z Friday cold front will bisect County Warning Area. At this time it appears that anafront 
precipitation will occur as ul trough lags behind fnt. Thus, have kept probability of precipitation in likely 
range for a good part of the day and into the nighttime hours. 
Instability is on the weaker side due to extensive cloud cvr, however it 
appears winds and frcg will be strongest. So will maintain mention of 
possible severe in the hazardous weather outlook. 


Frontal passage occurs around midnight Friday night with ul trough still hanging back 
to the west and not moving through until closer to 18z Friday. Will continue 
with likely probability of precipitation through this time with just chance showers bynd. Strong cold air advection 
will occur following frontal passage with overnight mins dipping into the 40s across 
the lake plain with lows in the upper 50s across southeastern counties. 


Cold air advection continues drg the day Friday with skies clrng from west to east and 
temperatures barely making it to near 60f. Winds will increases as pressure 
gradient tightens between surface lopres off the Atlantic Seaboard and 
building 1030mb hipres. Fairly raw day compared to past week or so. 


&& 


Long term /Friday night through Tuesday/... 
4 am Wednesday update... little to no changes made to the extended grids at this time. 


The 00z Wednesday model suite is still singing the same tune on the 
large-scale...with a deep upper-level trough over the Canadian 
Maritimes and the northestern states this Holiday weekend...leading to 
fairly chilly temperatures for late may (highs only from the 50s-middle 60s). 
One difference between the ec and GFS concerns the progressiveness 
of this upper trough and associated surface cold front. The ec shows only 
very slow eastward progress for at least the first half of the 
weekend...leading to lingering showers for Sat...perhaps even into 
sun. Meanwhile...the GFS builds surface ridging into New York/PA much more 
quickly...resulting in drier weather. We'll continue to side with the 
more progressive GFS...thus maintaining a precipitation-free forecast. 


As mentioned earlier...and also alluded to in the previous disc...the 
chilly nature of the air mass could well result in night-time lows down 
into the 30s for our normally colder locales. As we draw 
closer...and confidence increases in cold overnight 
lows...frost/freeze headlines may be required. We'll obviously continue 
to look closely at this sitn in the coming days. 


Early next week...model consensus points towards rising 
heights/modifying temperatures with time. 


Previous disc... at the start of the extended...deep upper-level 
troughing will be working off the East Coast with strong high 
pressure building southward across Great Lakes from central 
Canada. As this occurs...strong blocking south of Greenland will 
result in only a slow eastward migration of the exiting upper 
trough across New England and the Canadian maritime provinces. 
This will ensure arriving high pressure will dominate through the 
period with little to no precipitation expected. With a dry 
airmass firmly in place...expect a fairly wide diurnal range in 
temperatures with overnight lows easily falling into the upper 30s and 
lower 40s and highs only reaching into the lower to middle 60s. 
From this Vantage Point...it seems reasonable that conditions will 
become favorable for frost formation through the weekend and 
headlines will likely be needed at some point. 


&& 


Aviation /14z Wednesday through Sunday/... 
12z update... other than some MVFR visibility restrictions in fog/haze 
early this am...VFR should continue for a good chunk of the day. 
Isolated rain showers/thunderstorms and rain will be floating through cny through early 
afternoon...but coverage looks sparse enough to preclude their mention 
in the terminals over the near term. 


Later this afternoon...coverage of rain showers/thunderstorms and rain should increase...especially near 
ksyr and krme...so restrictive conds were inserted at that time. 
Later this evening...convective coverage should diminish again. 


Light surface winds this am...will become a bit gusty out of the S and 
SW this afternoon (20-25 kt)...before lessening this evening. 


Outlook... 


Thursday/Thursday night...MVFR possible in showers/thunderstorms. 


Friday...possible lingering restrictions in lower cigs/-shra. 


Sat-sun...VFR. Breezy. 


&& 


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


&& 


$$ 
Synopsis...pvn 
near term...cmg/pvn 
short term...pvn 
long term...cmg/mlj 
aviation...mlj/mdp