000 FXUS61 KBOX 090240 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 940 PM EST Wed Feb 8 2023 .SYNOPSIS... High pressure builds into the region tonight. Low pressure then tracks northwest of our region Thursday and Thursday night bringing showers to southern New England. Mainly rain is expected with this system, with a low probability of a wintry mix Thursday afternoon across far NW MA. Unseasonably mild temperatures, close to the records for the day, follow on Friday. Cooler and more seasonable weather returns this weekend. Low pressure moving off the mid Atlc coast is expected to remain well south of New England, but the northern extent of the precipitation shield may make it into portions of the region late Sunday into early Monday. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... 930PM Update... Clear conditions continue to dominate the region this evening, supporting healthy radiational cooling; the temperature dropping 4 degrees here at the office in just the last hour. Radiational cooling will continue for the next few hours but will be capped earlier across our western zones as high clouds move in from the SW. Otherwise, forecast remains on track, see previous updates for more detail. 640 PM update... High pres builds into New Eng tonight with diminishing winds becoming near calm. Clear skies will give way to increasing high clouds overnight. A period of good radiational cooling during the first half of the night will allow temps to fall quickly before leveling off later tonight. Expected lows will drop into the mid/upper 20s, except lower 30s near the coast. Forecast on track. Previous discussion... A building mid level ridge and increasing subsidence from an approaching surface high pressure center are allowing for increasingly clear skies over southern New England. While mid level moisture has held on longer than expected, clear skies finally arrived and should stick around until the early overnight hours. That's when an approaching warm front will move in, first in the upper levels, leading a deck of cirrus clouds to overspread from southwest to northeast. These clouds will thicken and lower through the night. So, while winds will come down tonight as the high moves overhead, this will be later in the night when cloudcover is thicker. So, have only tweaked low temperatures a bit lower to account for some radiational cooling. Expect lows in the upper 20s and low 30s. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... Thursday starts with mostly cloudy skies, quickly becoming overcast as the surface warm front lifts through. This is associated with a vertically stacked low which will move from the Great Lakes into Canada, well to our north and west over the next 24 hours. What this means for us is that any precipitation that falls will be in the form of rain, with temperatures on Thursday reaching well into the 40s. As the system moves closer it generates a 45 to 55 kt low level jet overhead which, while it will help provide lift for rain showers, will struggle to mix down to the surface. BUFKIT soundings show a stout inversion around 920 mb which should keep the stronger winds aloft until cold advection kicks in on Friday. The best chance for rain showers, especially early on, is for northern MA in closest proximity to the better forcing. While scattered showers are possible for all of southern New England during the evening and early overnight hours, rain shuts off after midnight as a mid level dry slot moves overhead. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Highlights... * Windy & unseasonably mild Fri. Near record high temps. * Cooler and more seasonable this weekend. Some rain may make into southern portions of SNE late Sun into early Mon, with a lower risk of rain or snow/mixed precip further N. * Above normal temps early next week Friday... Rather mild start to the day with temps well into the 40s to lower 50s. Cold front will be moving off the coast in the morning with cooling low level temps. Afternoon 925 mb temps around 5C with good mixing and westerly flow supports highs well into the 50s in the coastal plain and lower CT valley, with perhaps temps near 60 in a few spots across SE MA. Some diurnal cloud cover expected, otherwise partly to mostly sunny skies. The mild temps will be accompanied by windy conditions as well mixed boundary layer supports 25-40 mph gusts. Northern stream trough approaches Fri night with backing flow which will allow clouds to increase but area of southern stream moisture expected to remain to the south, with just a low risk a few showers could clip the Islands. Saturday through Monday... Northern stream trough sweeps through Sat morning followed by NW flow and drying column. Expect lots of sunshine and cooler temps in the upper 30s and lower 40s. Cold night Sat night as high pres builds into New Eng with good radiational cooling resulting in lows in the teens and 20s. Then a southern stream low will emerge off the mid Atlc coast Sun night passing well south of New Eng Monday. However, building ridge ahead of this system expected to allow moisture to lift further N and possibly get into SNE. Expect much of Sunday to be dry, but it is possible some rain may begin to move into south coastal areas by late Sun. There is still uncertainty with how far north precip shield will get but confidence is increasing in a period of rain getting to at least the south coast through Sun night. And there is enough ensemble support for a low to moderate risk of precip making it further N into SNE with the threat of some wet snow or mixed precip the further N it makes it across SNE. Gusty NE winds also a risk near the coast with a modest low level jet developing. It appears precip could linger into Mon, especially near the coast but trend will be for improving conditions later Mon as storm pulls away. Tuesday and Wednesday... Above normal temps expected Tue/Wed but lower confidence on PoPs/timing as an active pattern persists with multiple shortwaves rotating through a somewhat amplified flow pattern. GEFS and ECENS suggest mostly dry Tue with greater risk of showers Wed. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. 00Z TAF Update... Tonight... High Confidence. VFR with light northwesterly winds, less than 10 kt, calm across portions of interior southern of New England. Thursday... High Confidence in trends, moderate confidence in exact timing. VFR to start the day. Increasing clouds ahead of our next rainmaker after 15-18Z from west to east. MVFR and light rain showers develop during the afternoon hours. Periods of IFR at our western terminals possible before 00Z Friday, especially in heavier bands of rain. Calm winds become southerly by Thursday afternoon, increasing to about 15kt. Thursday night...moderate confidence. IFR in SHRA becoming VFR by 12Z. SW winds 15 to 20 kt. KBOS Terminal...High Confidence in TAF. VFR through the period. Mid level clouds scour out to clear conditions by late morning. Winds becoming West/Northwest winds 10-15 knots today with 20+ knot gusts by afternoon. Winds diminish tonight. KBDL Terminal...High Confidence in TAF. VFR through the period. Mid level clouds scour out to clear conditions by late morning. Winds becoming West/Northwest winds 10-15 knots today with 20+ knot gusts by afternoon. Winds diminish tonight. Outlook /Friday through Monday/... Saturday: VFR. Windy with local gusts up to 30 kt. Saturday Night: VFR. Sunday: VFR. Breezy. Slight chance RA. Sunday Night: VFR. Windy with areas of gusts up to 30 kt. Chance RA, slight chance FZRA, slight chance SN. Monday: Mainly VFR, with local MVFR possible. Windy with gusts up to 35 kt. Monday Night: VFR. Breezy. Tuesday: && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Tonight... High pressure builds over the coastal waters tonight with lighter winds and decreasing seas. Conditions will fall below small craft criteria across the outer waters overnight. Thursday... NW flow gradually shifts to the south and builds through the day Thursday. Winds remain below small craft thresholds. Seas gradually build to near 5 feet again. Thursday night...SW winds increasing to 15-20kt gusting 25 to 30 kt. Seas build to 5 to 7 ft for the outer waters. Outlook /Friday through Monday/... Saturday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Saturday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Sunday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain. Sunday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Chance of rain. Monday: Low risk for gale force winds with gusts up to 35 kt. Rough seas up to 10 ft. Chance of rain. Monday Night: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Tuesday: Winds less than 25 kt. Seas up to 5 ft. && .CLIMATE... Record Maximum Temps for Fri 2/10... Boston60/1990 Hartford55/1909 Providence58/1909 Worcester55/1909 && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 1 AM EST Thursday for ANZ250-254- 255. && $$ SYNOPSIS...KJC/BW NEAR TERM...KJC/BW/KS SHORT TERM...BW LONG TERM...KJC AVIATION...KJC/BW MARINE...KJC/BW CLIMATE...