Watching Friday storm

As the 06z model run of the GFS came out, southern New England snow lovers beamed with delight. Then the 12z run came out and threw hopes for snow out the door. Unfortunately, for the beginning of snow season and long term winter forecasting, it has been very difficult to get a straight answer from 2 consecutive model runs. When the GFS is faultering, we turn to the Euro, which for the first time that I can remember, is faultering similarly to the GFS. So now we are lost, and it becomes a game of wait and see.

The story: Models agree on clipper moving across the northern plains into the Ohio Valley. The models also agree on the energy from the clipper being transfered to the coast. Excitement builds as this takes on the picture of a rare November Miller B storm. However, there is a considerable amount of disagreement and flip-flopping as to the track of the resulting coastal low. The GFS 06z run brought the low very close to the 40/70 benchmark, allowing the precipitation shield to reach Keene, as well as a beautiful piece of frontogenisys that would bring a whopper of a band of snow across the area Saturday morning. This was all very nice, but the main problem was that the ensembles didnt support this at all. There is a very progressive (zonal) pattern in place right now that would whisk the low out to sea before even reaching 40N. The 12z run confirmed suspicions, taking the low 500 miles further south. It is a wait and see game. Cold air is there, and what isnt in place will be generated by a rapidly intensifying low if it approached the region. There needs to be a +PNA/-EPO pattern staying steady long enough for the trough in the east to stay in place. However, most of the model guidence at this point indicates the ridging in the west to move into the plains and the trough in the east to push the storm out to sea. For what its worth, the NWS has added 30% POPs for Friday and Friday Night in Keene.

NWS AFD:

ALL MEDIUM RANGE MODELS DEPICT SHORT WAVE TROF THAT AMPLIFIES
ALONG/JUST OFF E COAST WITH DEEPENING SURFACE CENTER SOMEWHERE OFF
MID ATLANTIC COAST. THIS WILL LIKELY IMPACT WEATHER FOR THE LATE FRI
THROUGH SAT TIME FRAME. SEE ENOUGH CONSISTENCY IN MEDIUM MODELS TO
SUGGEST AN INTENSIFYING LOW TO BECOME GALE OR STORM CENTER SE OF NEW
ENGLAND. BOTH GFS AND ECMWF SHOW SYSTEM FAR ENOUGH OFFSHORE FOR JUST
GLANCING BLOW FOR PRECIPITATION BUT POTENTIALLY SIGNIFICANT WIND/SEA
EVENT FOR AT LEAST OUTER COASTAL WATRS. GEM DEPICTS A SOLUTION MUCH
CLOSER TO COAST...IN FACT LOW CENTER PLACED NEAR CAPE COD ON 12Z
OPERATIONAL RUN. IF CLOSE ENOUGH TO COAST...PTYPE COULD BE AN ISSUE
BACK FROM THE IMMEDIATE COASTAL ZONES. BELIEVE WILL SEE VARIATIONS
IN MODEL INTENSITY AND TRACK AS WE GET CLOSER TO EVENT. WILL HAVE
MORE CONFIDENCE IN MODEL SOLUTIONS ONCE THE TRIGGERING SHORT WAVE
ENERGY MAKES ITS WAY INTO THE N AMERICA RADIOSONDE
NETWORK...PROBABLY TUE NIGHT/WED TIME FRAME.

If nothing else, we can bank on the "weekend rule" which turns out well in the past. Basically, many historical storms have occured between Friday and Monday. Holidays are exceptions (such as the Valentines Day storm last winter which was on a Wednesday). So anyway, the weekend rule is a go for this storm.