859 FXUS61 KBOX 140828 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 328 AM EST Thu Feb 14 2019 .SYNOPSIS... Drier and cooler weather follows overnight into Thursday followed by a brief warm-up Friday ahead of an approaching cold front. The weather pattern from this weekend into the middle of next week is a trend toward colder and mainly dry weather. The next chance of widespread precipitation not until the middle of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Sheared shortwave has moved E of the region and CAA SC follows in its wake, assisted by both upslope flow in the Berkshires and great Lake Moisture. Downslope is preventing these SC from pushing much further E than the Worcester Hills. Even these are likely short lived as subsidence associated with an inverted ridge will begin to invade from the S, as the ridge crests about mid day. Modest CAA, even with enhanced mixing will limit warming in comparison to Wednesday. Highs will mainly remain the mid to upper 30s with some spots in the low 40s. Breezy thanks to the aforementioned mixing, gusts around 20-25 kt (20-30 mph) at times. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... Tonight... Gradual development of low-mid lvl warm advection as return flow develops in advance of Great Lakes low pres and attendant warm front. The warm advection, as well as moisture loading/cloud increase through the overnight hours will limit cooling. Min temps will drop into the 20s through about midnight or early AM before sfc dwpts prohibit further drops. S flow flow aloft around 40-50 kt by 12Z but the sfc front may lag the upper lvl front somewhat. Therefore, am holding off on POPs until after 12Z, feel that light precip will only be entering the W periphery of S New England around sunrise Fri. Fri... Primary change from recent forecasts is to increase risk for SCT-NUM SHSN then SHRA. PWAT plume nearly 1.5 std deviations above normal and warm/cold frontal lift strong enough to support at least disorganized precip. Some modest SN accumulations mainly across NW MA as these will be the areas that remain below freezing in the low levels the longest into the daylight hours Fri. Low risk for a few spots reaching up to an inch. Otherwise, the LLJ will lead to H92 temps above 0C all the way to the NH border per latest runs and H85 temp anomalies are near +6C by mid afternoon so most precip should change to through the morning. Cold front approaches by evening, increasing the risk especially across E MA and RI. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... */ Highlights ... - Mild weather lingers into Saturday - Trending colder Saturday night thru the middle of next week - Mainly dry weather with the next chance of widespread precip not until the middle of next week */ Overview ... Amplified and somewhat suppressed northern stream yields a trend toward colder weather beginning Saturday night and continuing into next week. Good model agreement among ensembles and deterministic guidance for a very strong subtropical jet (up to 200 kt jet) to flood the CONUS with Pacific energy. However with confluent flow across the Northeast this weekend, any Pacific moisture tracks south of southern New England yielding dry weather here. However by early next week a western CONUS trough develops and in response a downstream southeast ridge, shifting the storm track farther north closer to southern New England. However given the lack of high latitude blocking a progressive upper air pattern persists, not supportive of any significant precip events here in southern New England. */ Details... Friday night ... Cold front moves across the region with the best chance of showers over southeast MA including Cape Cod and the Islands where deeper moisture exist. After highs in the 50s Friday turning much cooler behind the front with mins by Sat morning ranging from the upper 20s to lower 30s. This Weekend ... Post frontal airmass overspreads the region Saturday but core of cold air arrives Sat night behind trailing short wave. Thus temps Sat will be very close to normal with highs in the upper 30s to lower 40s. Morning clouds exit offshore with cold front and gives way to at least partial sunshine but diurnal/post frontal clouds scattered to broken clouds likely develop in the afternoon given cyclonic flow aloft. Confluent flow provides dry weather Sunday although clouds may be on the increase late in the day as pacific energy/moisture approaches from the southwest. Although cooler than Saturday with highs Sunday in the 30s. Sunshine thru at least the first half of the day along with light winds will make it feel more pleasant. Confluent flow will likely erode and shunt deep layer moisture south of New England. Thus dry weather likely prevails thru Sunday night. Next Week ... Confluent flow and 1030+ mb high pressure likely keep the region dry and cold Monday and Tuesday. However as southeast ridge develops mid week confluent flow over New England lifts northward, opening the door for moisture from subtropical jet to track up the eastern seaboard. Thermal profiles and ensemble data suggest cold air is initially deep enough to support snow but could transition over to a wintry mix. Still 6 days away so don't want to be too deterministic here. Doesn't appear to be a significant qpf event as approaching short wave trough appears to deamplify as jet energy rides up and over southeast ridge. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Friday/...High confidence Through this evening... VFR. W winds remain elevated through the day. Gusts 20-25 kt at times, diminishing after 20Z. Tonight... Mainly VFR although with increasing clouds and gradually lowering CIGS. Winds gradually pivot around to the E-SE. Fri... Predominantly MVFR conditions in lowered CIGS. Occasional SHRA/BR with MVFR vsbys as well, especially after sunrise, into late afternoon from W-E. KBOS Terminal...High confidence in TAF. KBDL Terminal...High confidence in TAF. Outlook /Friday Night through Monday/... Friday Night: Mainly VFR, with local MVFR possible. Windy with local gusts up to 30 kt. Slight chance SHRA. Saturday: VFR. Saturday Night: VFR. Breezy. Sunday: VFR. Sunday Night: Mainly VFR, with local IFR possible. Slight chance SHSN. Washingtons Birthday: MVFR/IFR conditions possible. Slight chance SHSN. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Friday/...High confidence. Through tonight... Small Craft Advisory conditions with gusts 25-30 kt across the waters through afternoon. Offshore, seas will take more time to dissipate below 5ft. Advisories will linger through the afternoon and early overnight hours. Fri... Increasing S flow with at least Small Craft Advisory gusts by mid morning. Low risk for Gale gusts across the E waters which may need to be watched. Otherwise, some showers by mid day and localized fog with reduced vsbys. Outlook /Friday Night through Monday/... Friday Night: Low risk for Small Craft Advisory winds with local gusts up to 30 kt. Rough seas up to 10 ft. Chance of rain showers. Saturday: Winds less than 25 kt. Local rough seas. Slight chance of rain showers. Local visibility 1 to 3 nm. Saturday Night: Winds less than 25 kt. Seas up to 5 ft. Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft. Sunday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of snow showers. Areas of visibility 1 to 3 nm. Washingtons Birthday: Winds less than 25 kt. Seas up to 5 ft. Slight chance of snow showers. Visibility 1 to 3 nm. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 4 PM EST this afternoon for ANZ231>234-251. Small Craft Advisory until 1 PM EST this afternoon for ANZ230- 236. Small Craft Advisory until 7 PM EST this evening for ANZ235- 237-250. Small Craft Advisory until 10 PM EST this evening for ANZ254>256. && $$ SYNOPSIS...Nocera/Doody NEAR TERM...Doody SHORT TERM...Doody LONG TERM...Nocera AVIATION...Nocera/Doody MARINE...Nocera/Doody