498 
fxus61 kbox 201529 
afdbox 


Area forecast discussion 
National Weather Service Taunton Massachusetts 
1029 am EST Thursday Nov 20 2008 


Synopsis... 
mainly dry conditions and unseasonably cold air will prevail across 
southern New England through this weekend. High pressure will move 
offshore Monday...then a storm system could affect southern New 
England early next week. 


&& 


Near term /until 6 PM this evening/... 
partly sunny skies prevailed across the area late this morning 
as a weakening short wave continued to push across the region. Given 
slightly more optimistic conditions...have increased temperatures and 
diminished sky cover this afternoon...except coastal locations and 
the interior high terrain where the cold air advection pattern will 
be more conducive for cloudiness. 


&& 


Short term /6 PM this evening through 6 PM Friday/... 
the area will be in between short wave troughs tonight...although 
general cyclonic flow will continue to aid in the delivery of 
unseasonably cold air. Expect varying amounts of clouds and very cold 
temperatures...with lows in the teens across a lot of southern New England. 
Temperatures Bay bust a bit high or low in some locales depending on cloud 
cover. For now...played sky cover conservatively at this time...which should 
allow mins to get down close to mavmos numbers. 


Deep upper trough moves into the region on Friday. This will aid in 
the development of low pressure well offshore of southern New England 
during the day. The low will remain far enough offshore to keep it/S 
precipitation shield out to sea...although Nantucket could be grazed by a 
few snow showers. The rest of the area will see partly sunny skies 
with perhaps a few flurries. Temperatures remain a good 10 to 15 degrees 
below normal with highs in the 30s. Shaved a few degrees off MOS with 
1000-500mb thicknesses in the 510-515dm range. Could even be a bit 
colder. 


&& 


Long term /Friday night through Wednesday/... 
offshore coastal storm will be a miss for southern New England but will serve to 
bring reinforcing shot of Arctic air to the region Friday night and 
Sat. Most of the precipitation from the storm will remain to the south and 
east...but cant rule out a few snow showers clipping cape/islands 
Friday night with ocean effect snow showers likely developing just to 
the east as very cold air moves in over warmer water. Low level 
trajectory is northwest which will keep ocean effect east of cape. There 
may also be some flurries Friday night in the interior as upper trough 
moves across region. Moisture is lacking but 500 mb temperatures cooling 
to -40c. 


The unseasonably cold airmass will be the main story for Sat as 850 
mb temperatures drop to -16c. 2m temperatures support maxes only in the upper 20s 
to lower 30s Sat which is 15-20 degrees below normal...so we 
undercut MOS temperatures. A dry day expected with pt-mosunny skies but a 
gusty northwest wind will add to the chill. Wind chills may be down in the 
single numbers early Sat morning...recovering into the teens and low 
20s during the day. A very cold day for late Nov. 


The gusty northwest winds will slowly diminish Sat night as high pressure 
builds in from the west. Under moclear skies...min temperatures will drop 
into the teens and low 20s. 


High pressure overhead on Sunday but airmass still rather cold with 850 
mb temperatures starting out around -14c and slowly increasing to -10c. 
Maxes will likely remain in the 30s across southern New England which will be about 
10 degrees below normal. 


Looking ahead to early next week...global models indicate a potent 
upper trough/upper low digging southeast from the upper Midwest...but there 
are differences in the handling of this system and the evolution of 
a possible coastal storm developing off the coast sometime Tue/Wed. 
Overrunning ahead of primary low will bring chance rain/snow showers 
Monday/Monday evening...then a period of heavier precipitation possible beyond 
Monday night depending on what happens with the coastal low. 
GFS/European model (ecmwf) consensus suggests mainly rain for the coastal plain with 
some snow possible in the interior. UKMET is colder with snow 
possible to the coast. This is still too far out with considerable 
model spread so forecast confidence in details is very low. 


&& 


Aviation /15z Thursday through Monday/... 
today...VFR...cigs occasionally bkn060-100. 


Tonight...VFR. 


Friday...VFR. 


Outlook...Friday night through Monday... 


Through sun...mainly VFR...with occasional MVFR ceilings possible hya-ack Friday 
night. Gusty northwest winds to 30kt possible late Friday night into Sat. 


Monday...VFR...but possibly lowering to MVFR in developing rain/snow 
showers late. 


&& 


Marine... 
kept the Small Craft Advisory going for today into this evening for the outer waters 
as buoys still reporting 5-10 feet seas. Slight chance of 25 knots gusts 
later this afternoon and evening as well. 


Winds and seas subside as tonight progresses. Low pressure develops 
well south of Nantucket Friday. This will likely necessitate 
additional Small Craft Advisory issuances later in the day. 


Outlook...Friday night through Monday... 


Northwest winds will be increasing Friday night in the wake of a coastal 
storm...with gales possible Sat into Sat night. Small Craft Advisory westerly winds 
may linger into sun...then diminishing Sun night as high pressure 
builds into our region. Southerly winds increasing to Small Craft Advisory levels 
Monday ahead of next storm moving into the Great Lakes. 


&& 


Box watches/warnings/advisories... 
CT...none. 
Massachusetts...none. 
New Hampshire...none. 
Rhode Island...none. 
Marine...Small Craft Advisory until midnight EST tonight for anz250-254- 
255. 


&& 


$$ 
Synopsis...kjc/ekster 
near term...ekster/Strauss 
short term...ekster 
long term...kjc 
aviation...kjc/ekster 
marine...kjc/ekster