449 
fxus61 kbox 231023 
afdbox 


Area forecast discussion 
National Weather Service Taunton Massachusetts 
523 am EST Monday Nov 23 2009 


Synopsis... 
low pressure along the Carolina coasts today will pass east of Cape Cod 
late Tuesday...possibly as a gale noreaster. Weak high pressure covers 
New England Wednesday. A large gale will be centered near the New 
England coast Friday then move into the Maritimes this weekend. 


&& 


Near term /until 6 PM this evening/... 
high pressure has made its way to Nova Scotia early this morning. Models 
continue to signal low pressure developing off the southeast U.S. Coast... 
tracking NE during the day. The pressure gradient between this 
developing low and the high will cause east-NE winds to pick up mainly 
this afternoon across the South Coast...Cape Cod and the islands. 


Noting northern edge of precipitation remaining well S of New England on 
the NE regional mosaic radar at 09z...and remaining offshore early 
this morning. Feel several of the models trying to bring precipitation into 
the region too quickly...though might see patchy drizzle along the 
coast during the day with the steady onshore wind. Did not mention 
in the zones or grids for now...not terribly confident of this right 
now. However...did bring in chance probability of precipitation to south coastal areas by 
midday...reaching S New Hampshire by early this evening. 


Models not handling the temperature profile well at all...at least early 
this morning with the non-diurnal steady or slowly rising readings 
so far. By midday...expect temperatures to reach around 50 degrees...and 
maybe the middle 50s across the Outer Cape and islands as east-NE winds 
freshen. Kept temperatures in the upper 40s-around 50 inland. 


&& 


Short term /6 PM this evening through 6 PM Tuesday/... 
short range models still having trouble locking in on track and 
intensity of the approaching low. Appears the GFS and rgem were 
outliers as compared to most of the other model solutions...so 
leaned toward a blend of the non-GFS ensembles with a little 
contribution from the sref. Appears the low will pass southeast of 
Nantucket Tuesday morning. Have continued with likely-categorical 
probability of precipitation tonight...then will shift offshore on Tuesday. Right now... 
feel the heaviest precipitation will remain offshore...but some heavier 
rains may clip the cape and islands overnight. 


Models did not handle lows for tonight well at all considering the 
onshore flow as well as precipitation and cloud cover...so leaned toward a 
blend of the previous forecast with the MOS guidance with 
adjustments to account for somewhat milder readings. Kept temperatures 
above freezing at all locations...and still may be a bit too cold 
over S New Hampshire /mid-upper 30s forecast for now/. As for Monday...leaned 
toward previous forecast along with the 2m NAM/GFS temperatures which tend 
to remove the MOS seasonal effects. Went with readings in the 
Lower-Middle 50s. 


Only other problem could be a brief wind increase late tonight into 
Tuesday morning. Have kept winds below advisory criteria for Cape 
Cod and the islands for now...but will need to monitor this in case 
the low is a bit stronger than currently forecast...as well as moves 
a bit closer to the coast. 


&& 


Long term /Tuesday night through Sunday/... 
model uncertainty Tuesday night-Thursday morning leads to a below average confidence 
on forecast details this period then high confidence for combined Great 
Lakes coastal merger Thursday night or Friday followed by high confidence on 
a developing blustery weekend. 


Tuesday night-Thu...maintained considerable continuity with the 4pm Sunday 
kbox forecast due to the various model outputs. Overall..leftover r or 
drizzle Tuesday night. Probably dry Wednesday into early Thursday but am uncertain 
due the resultant surface weather being dependent on subtle bl wind 
direction/associated terrain lift. The 00z GFS MOS was not heavily 
weighted...due to uncertainty regarding clearing and the output of 
the NAM and ggem temperature fields. 


Late Thursday into the weekend...blv model consensus favors some sort of low pressure 
moving to New England with a period of showers. Thunder is possible 
but did not forecast in the grids or write into the severe weather potential statement as its day 5. 
For the coast this could be either or both a brief Ely gale Friday 
followed by a blustery weekend with pockets of westerly gale force gusts. 
Temperatures were modified at night...upward due to expected mixing and the 
00z/23 GFS MOS. 


Erosion...constancy of onshore flow and large Ely ocean swells of 10 
feet Tuesday into Wednesday and possibly again Friday. We cant forecast the extent of 
erosion but it could be significant. 


&& 


Aviation /10z Monday through Friday/... 
today...MVFR-IFR ceilings expected. May see local IFR ceilings moving into S 
coastal areas during the afternoon...as well as MVFR visibilities in patchy 
fog. Low chance of local drizzle along the coast. 


Tonight...MVFR-IFR ceilings expected...with local LIFR ceilings possible on 
Cape Cod and the islands. Areas of MVFR-IFR visibilities in rain and fog. 


Tuesday...MVFR ceilings/visibilities in rain mainly central and eastern areas. 
May see improving conditions during the afternoon across the CT 
valley. 


Outlook /Tuesday night through Friday/... 


Tuesday night through Thursday...considerable uncertainty. Low confidence. 


Generally VFR interior though with a period of IFR St/fog early Wednesday 
and early Thursday. 


Along the coast-especially Cape Cod and the islands...generally MVFR or IFR 
ceilings outlooked. Leftover rain/drizzle Tuesday night. 




Thursday night and Friday...high confidence of IFR conds in rain with a period 
of gusty east 25 to 35 knots coast...possibly shifting to west Friday afternoon along 
with improving conds. 


&& 


Marine... 
today...E-NE winds gusting up to 25-30 knots mainly on the outer 
waters...though may reach the S sounds by this afternoon. Noted the 
wna wavewatch model was running a foot or so too low this morning. 
Buoy 008 well southeast of Nantucket up to 10 feet already at 09z and buoy 
018 up to 7 feet. Have increased the seas on the outer coastal 
waters. 


Tonight and Tuesday...with the low passing southeast of Nantucket late 
tonight...may see a brief period of gale force gusts on the outer 
waters as well as Nantucket Sound and Cape Cod Bay. Have put up a 
gale watch for late tonight into Tuesday morning for this 
possibility. Wavewatch has also forecasted seas up to 13 feet on the 
eastern outer waters. 


Outlook /Tuesday night through Friday/... 
leftover Small Craft Advisory conds Tuesday evening shift to hazardous seas Small Craft Advisory Wednesday and Thursday 
in the outer waters then another gale condition possible Friday. 


&& 


Equipment... 
National Weather Service Boston-Taunton point and click has delays in updating by about 45 
minutes- a continuing recent problem. 


Tdwr in the Boston area continues ots ufn. 


44020...any problem with this Nantucket Sound buoy will probably be 
updated on its maintenance link by ndbc later today. 


&& 


Box watches/warnings/advisories... 
CT...none. 
Massachusetts...none. 
New Hampshire...none. 
Rhode Island...none. 
Marine...gale watch from late tonight through Tuesday afternoon for 
anz232-254-255. 
Small Craft Advisory until 1 am EST Tuesday for anz232-254>256. 
Small Craft Advisory until 1 PM EST Tuesday for anz233>235-237. 
Small Craft Advisory from 7 am to 1 PM EST Tuesday for anz230- 
236. 
Gale watch from Tuesday morning through Tuesday afternoon for 
anz231-250. 
Small Craft Advisory from 1 am to 7 am EST Tuesday for anz231. 
Small Craft Advisory until 7 am EST Tuesday for anz250. 
Small Craft Advisory from 1 am to 1 PM EST Tuesday for anz251. 
Gale watch from late tonight through Tuesday morning for 
anz256. 


&& 


$$ 
Synopsis...drag/evt 
near term...evt 
short term...evt 
long term...drag 518a 
aviation...drag/evt 
marine...drag/evt 
equipment...drag 

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