Scientific Forecaster Discussion

NWS Discussion
			
				

Area forecast discussion 
National Weather Service Binghamton New York 
1014 am EDT Thursday may 23 2013 


Synopsis... 
a cold front will approach the region by this evening...then 
slowly cross the area late tonight or early Friday. Showers and 
thunderstorms will likely precede and accompany the front through 
this evening...with showers then continuing behind the front later 
tonight and Friday...along with much cooler temperatures. 


&& 


Near term /until 6 PM this evening/... 
1010 am update... 
forecast in fairly good shape this morning...only minor changes needed 
at the present time. Regional radars showing an area of light 
showers working northeast through the bgm forecast area on the heels of 
a weak shortwave trough now lifting north through central New York with 
latest water vapor imagery showing a notable dry slot now entering 
western New York. So far current activity has displayed no convective 
trends and as a result...have backed off thunder mention until 
early afternoon. 


Main concern going into the afternoon remains possible severe weather 
development as long advertised cold front approaches from the 
northwest. That said...forecast models continue to indicate only 
weakly unstable conditions by this afternoon/evening which may be 
a result of current cloud cover aloft. That said...the potential 
does exist for model underestimation of this afternoon/S 
instability as periodic breaks are expected to move into the 
region later today. That said...RUC and local WRF BUFKIT and AWIPS 
plan view forecasts show nearly 800 j/kg of MLCAPE by this afternoon 
which may not be too far off if some clearing does move into the 
area. The other thing that today/S setup has going for it is 
decent dynamics aloft as upper divergence will be increasing 
through the day as a jetstreak strengthens over the region in 
confluent flow aloft. Considering 0-6km bulk shear vectors are 
oriented nearly parallel to the arriving cold front...main 
development will likely be linear in fashion with strong winds 
likely being the biggest threats. Obviously a lot to monitor and 
updates will be made as needed. Current thinking is today/S 
activity will hold off until middle to late afternoon at the 
earliest. Remainder of near term forecast looks to be in good shape 
with middle to upper 70s expected for daytime highs. 


545 am update... a band of -shra/isolated thunderstorms and rain continues to March across 
the County Warning Area at this time...likely associated with an upper-level wave. We expect showers 
to impact much of the region through 14-15z...followed by a lull in 
precipitation for most of this afternoon. 


Although a fair amount of cloud debris should be resident today over 
the northestern states...ahead of the surface cold front...a few breaks of sun are 
not out of the question during the early and middle-afternoon hours. This will 
likely provide enough heating/destabilization to fuel another round 
of rain showers/thunderstorms and rain late in the day...and especially this evening...as the front 
itself apprchs. The latest rap/WRF/GFS consensus suggests the 
potential for 500-1000 j/kg of cape this afternoon...along with improving 
deep-layered shear...and some height falls aloft. Thus...organized 
linear features seem plausible...with damaging winds the primary 
threat. 


&& 


Short term /6 PM this evening through Saturday night/... 
555 am update... our model suite continues to trend slower/less 
progressive...with the amplified upper-level trough to impact the region 
through at least the first half of the Holiday weekend. 


Post-frontal showers have been well advertised in our forecast for 
Friday...along with much cooler temperatures...and nothing has changed in this 
regard. In fact...readings Friday likely will hold about steady in the 
Lower-Middle 50s...and may even edge downward a bit as the day GOES on. 


We've nudged probability of precipitation upward a bit for Friday ngt/Sat...mainly in our eastern 
zones...to account for the likelihood of a slower departure of 
moisture/forced lift...as it now appears that a closer upper-level 
system will linger along the coast at least into Sat. 


Although drying/clearing skies now looks slower to occur...we 
still anticipate that some clearing will make it into our western zones 
by Sat/Sat evening. Thus...present indications are are that the best shot for 
frost/freeze conds will be in the western half of the forecast area Sat night/early 
sun am. 


&& 


Long term /Sunday through Wednesday/... 
period begins with a large and cool Canadian hp building into the area in 
the wake of a deep low over new eng. 800 mb temperatures drop to near 0c by 
Sun morning with the possiblity of some leftover precipitation in the eastern zones. 
Latest GFS and European model (ecmwf) are a bit slower lifting the upper low north 
into eastern Canada on Sunday indicating the potential for a 
cloudier cooler day on Sunday than previous forecast. Otherwise 
still expect steady improvement next week as the upper low finally 
lifts north into the Maritimes. Have lowered temperatures 
slightly on Sunday to account for latest GFS/European model (ecmwf) cooler trend... 
otherwise no significant changes. 


&& 


Aviation /14z Thursday through Monday/... 
heaviest showers and thunderstorms have ended across the taf sites 
early this morning but occasional showers will continue through 
today in moist flow ahead of an approaching cold front. Isolated 
to scattered thunder could occur through the day but coverage and 
duration not enough to include in the tafs at this time. The cold 
front will cross the area from west to east tonight with 
occasional showers continuing. Again there could be some thunder 
but coverage and duration not enough to include in the tafs at 
this time. 


Winds will be southwest at 5 to 15 kts today shifting to northwest 
at 5 to 15 kts tonight. 


Outlook... 


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


Sun - Monday...VFR. Breezy. 


&& 


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


&& 


$$ 
Synopsis...mlj 
near term...cmg/mlj 
short term...mlj 
long term...dgm/mse 
aviation...mse