000 FXUS61 KBOX 030533 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 1233 AM EST Fri Dec 3 2021 .SYNOPSIS... A cold frontal passage brings a few showers to the region this evening, followed by windy & colder temperatures overnight into Friday. Mainly dry and chilly weather is on tap this weekend. This will quickly be replaced by very mild temperatures along with strong winds & some rain showers Monday. Much colder/drier air works into the region late Monday night into Tuesday. An approaching low pressure system may bring accumulating snow/ice to parts of the interior on Wednesday with rain favored along the coastal plain. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 1230AM Update: Cold front exits eastern Massachusetts with a few lingering rain showers across the Cape and Islands through 08z, otherwise drying trend continues. Behind the front gusty southwest wind becomes west at 20 to 30 MPH. Gale Warnings continue for all waters into Friday late morning/early afternoon. Upslope rain/snow showers are possible across far western Massachusetts overnight. We don't expect much in the way of accumulation outside of a trace to a few tenths of an inch of new snow. Temperatures continue to fall overnight as colder air is advected into southern New England. As of 1230am temperatures range between 40F and 50F. Overnight the temperatures will fall into the low 20s for eastern slope communities of the Berkshires to the low 30s in the Worcester Hills, low/mid 30s for CT River Valley and coastal plain of southern New England. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/... Tomorrow Surface high pressure builds over the region tomorrow resulting in diminishing wind speeds out of the west/northwest. Deep northwest flow advects cooler drier air into southern New England with PWATs <0.25" and temperatures at 925 hPa ranging from -5 to -7 C. This will support mostly sunny skies and high temperatures in the upper 30s across the interior to the low 40s near the coast. Tomorrow Night Winds continue to weaken tomorrow night as high pressure takes control of the region. Clear skies and weak winds should support fairly strong radiational cooling. This will allow temperatures to fall to the low 20s across portions of northwest MA. Elsewhere across the interior and coastal southern New England temperatures will range from the mid 20s to low 30s. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Highlights... * Dry/chilly this weekend other than a passing flurry/snow shower Sat * Strong to perhaps damaging winds Mon & becoming very mild with highs into the 60s with a low risk for a few spots to approach 70 * Some showers Mon/Mon evening followed by much colder temps Tue * Potential for accumulating snow/ice across the interior on Wed with mainly rain favored near I-95, but nothing set in stone Details... This Weekend... Mainly dry and chilly weather is in store for our region this weekend as high pressure gradually builds in from the west. We can not rule out a brief passing flurry/snow shower with a moisture starved shortwave, but nothing impactful expected. High temperatures will mainly be in the upper 30s to the lower 40s; which is near/slightly below normal for this time of year. Monday... Quite the start to the next work week with strong winds and very anomalously high temps anticipated on Monday. This is a classic latitude pattern with below normal temps across much of central/eastern Canada, while above normal temps are across the souther U.S. States. This large temp gradient across North America is setting the stage for large temperature variations; which Monday will depict. Going into more details on Monday, A strong shortwave trough will drop down into the Great Lakes. This will allow Meridional flow to develop across our region Monday; drawing up anomalous warmth. Even the MEX guidance which trends towards climatology currently has a high of 65 at both Boston/Providence. Given 850T warming to between +8C and +10C and excellent mixing on southwest flow, high temperatures should reach well into the 60s in many locales. In fact, it is not out of the question that a few spots take a run at 70 if enough solar insolation is realized. Periods of showers are expected at times Mon into Mon evening, but an extended period or two of dry weather may allow for a period of partial sunshine Monday. The big concern on Monday into Monday evening will be the potential for strong to perhaps damaging wind gusts. Guidance indicates southwest winds of 60 to 70 knots at 850 MB. Bufkit soundings indicate that the atmosphere should be extremely well mixed given boundary layer warmth. The result will be the potential for southwest wind gusts of 40 to 60 mph, but too many moving parts to nail down the magnitude. Another surge of strong winds may occur late Monday night with the frontal passage. We will have to monitor this potential closely over the next few days for the potential of strong to damaging winds. Tuesday... As mentioned earlier, given the amount of cold to our north and warmth to our south pretty wild temperatures swings expected. Dry weather will follow the cold frontal passage later Mon night, ushering in much colder air for Tue. It will be dry, but blustery and much colder with highs temps only in the 30s to near 40. Wednesday... Appears to be a decent shot for at least a period of accumulating snow/ice across the interior on Wednesday at the onset. Antecedent airmass is rather cold; so if the surface low tracks far enough to our south a snowstorm would occur across the interior. This is a scenario that the 12z ECMWF depicts. However, there is not really much blocking so a further northwest solution with a more limited period of snow/ice at the onset and a lot more rain are possible too. This is what the 12Z CMC/GFS indicate. Across the coastal plain; odds would favor mainly rain but that is certainly not set in stone. So in a nutshell, it is way too early to say much more at this point. But the potential for some accumulating snow/ice exists on Wednesday with the greatest risk across the interior. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. 06Z Update... Through 12z: High Confidence. VFR. Isolated -SHRA linger across eastern Massachusetts, Cape Cod, and Islands through 08z. Winds shift to the W with gusts of 20 to 30 knots with a few gusts up to 35 knots possible in the high terrain and areas near the coast. Today: High Confidence. VFR with NW wind gusts of 25 to 35 kts. Tonight: VFR. Diminishing westerly wind gusts. KBOS TAF...High confidence. KBDL TAF...High confidence Outlook /Saturday Night through Tuesday/... Saturday through Sunday: VFR. Breezy. Sunday Night: Mainly VFR, with local IFR possible. Windy with local gusts up to 30 kt. Chance SHRA, slight chance FZRA. Monday: Mainly MVFR, with local IFR possible. Strong winds with gusts up to 45 kt. SHRA likely. Monday Night: Mainly VFR, with areas MVFR possible. Strong winds with gusts up to 40 kt. SHRA likely. Tuesday: VFR. Windy with local gusts up to 30 kt. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tonight Gale force winds from 30-40 mph ramp up overnight behind a passing cold front. This will support rough seas with significant wave 4 heights of 10 feet or higher for the outer marine zones. Gale warning in effect through tomorrow afternoon. Tomorrow Gale force winds linger into the late morning/early afternoon before gradually diminishing into tomorrow evening. Seas will subside with the winds. Tomorrow Night West/northwest winds persist tomorrow night. Otherwise fairly calm conditions for early December. 0-3 foot seas for the near-shore zones and 4-6 feet for the outer marine zones. Outlook /Saturday Night through Tuesday/... Saturday: Winds less than 25 kt. Seas locally approaching 5 ft. Saturday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of seas approaching 5 ft. Sunday: Winds less than 25 kt. Seas locally approaching 5 ft. Sunday Night: Moderate risk for Small Craft Advisory winds with local gusts up to 30 kt. Local rough seas. Chance of rain showers. Monday: Moderate risk for gale force winds with gusts up to 40 kt. Rough seas up to 12 ft. Rain showers likely. Monday Night: Moderate risk for gale force winds with gusts up to 45 kt. Rough seas up to 12 ft. Rain showers likely. Tuesday: Low risk for gale force winds with gusts up to 35 kt. Rough seas up to 11 ft. && .TIDES/COASTAL FLOODING... Tide heights are rising to their December monthly highs over the weekend. The following are the astronomical heights and do not include surge values from local wind/weather conditions. Boston Saturday 12.1 feet 1029 AM Sunday 12.2 feet 1120 AM Monday 12.0 feet 1214 PM Nantucket Saturday 4.3 feet 1129 AM Sunday 4.4 feet 1224 PM Monday 4.4 feet 120 PM Providence Saturday 5.9 feet 732 AM Sunday 5.9 feet 824 AM Monday 5.8 feet 917 AM && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Gale Warning until 1 PM EST this afternoon for ANZ231>235-237- 250-251-254>256. Gale Warning until 10 AM EST this morning for ANZ230-236. && $$ SYNOPSIS...Frank/RM NEAR TERM...Gaucher SHORT TERM...RM LONG TERM...Frank AVIATION...Frank/Gaucher MARINE...Frank/RM TIDES/COASTAL FLOODING...Staff