Point Forecast Updated Tue Jun 25, 2019 1:15pm EDT
Showers with a chance of thunderstorms. Cooler. Near steady temperature around 70. Southeast winds 5 to 10 mph. Chance of rain 90 percent.
Mostly cloudy. Patchy fog. Showers with a chance of thunderstorms in the evening. Humid with lows in the lower 60s. Southeast winds 5 to 10 mph, becoming west after midnight. Chance of rain 80 percent.
Partly sunny. Patchy fog in the morning. Highs around 80. North winds around 5 mph, becoming northeast in the afternoon.
Partly cloudy. Patchy fog. Lows in the lower 60s. Southeast winds around 5 mph.
Mostly sunny. Humid with highs in the mid 80s. North winds around 5 mph, becoming south in the afternoon.
Mostly clear. Lows in the mid 60s.
Mostly clear. Highs in the upper 80s.
Partly cloudy. Lows in the upper 60s.
Mostly cloudy. A chance of showers and thunderstorms. Highs in the mid 80s.
Mostly cloudy. A chance of showers and thunderstorms. Lows in the mid 60s.
Partly sunny with a chance of showers. Highs in the upper 70s. Chance of rain 40 percent.
Mostly cloudy with a chance of showers. Lows around 60. Chance of rain 30 percent.
Mostly sunny. Highs in the mid 70s.
000 FXUS61 KBOX 251944 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 344 PM EDT Tue Jun 25 2019 .SYNOPSIS... An approaching cold front and wave of low pressure will bring a period of widespread showers and a few embedded thunderstorms with locally heavy rainfall this afternoon, heaviest over eastern CT into RI and eastern MA. Summer like warmth is expected Wednesday through Friday with a few showers and thunderstorms at times, but should be mainly dry. A cold front sweeps south through Southern New England Saturday bringing another chance of showers and thunderstorms. Cooler weather then moves in Sunday and Monday, followed by warming Tuesday. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... *** Locally heavy rainfall this afternoon along with a low risk of localized urban and poor drainage flooding, with greatest risk over RI and eastern MA *** 215 PM update ... No change from previous forecast. Current thinking based on latest satellite and radar trends along with Hi Res guidance is for heavy showers with embedded thunder to impact eastern CT/RI and eastern MA this afternoon and possibly impacting the late day commute with localized street/highway flooding. Earlier discussion below. =============================================================== Warm front with anomalous moisture plume (PWATs up to 2.1 inches from Long Island southward per SPC mesoanalysis) approaching southern New England from the southwest. Two areas of heavy rain at the moment, first area is over northwest MA. This region will lift north into VT/NH as low to mid level jet advects northeast. Greater area of interest is rain with embedded convection over Long Island southward across the ocean. Unfortunately none of the model qpf or simulated radar reflectivity fields capturing this area very well. Some of the 00z CAMs model doing a better job but differ on simulations thru this afternoon with some outcomes increasing convection while others weakening. However model mass fields all agree on low level jet fueling this convection will strengthen this afternoon as it traverses northeast across RI and eastern MA. This is being verified on latest GOES16 satellite imagery with cloud tops cooling and lightning activity picking up. Thus our concern for heavy rain and flood threat continues across RI into eastern MA this afternoon. Previous forecast captures these trends nicely so no major changes with this update. && .SHORT TERM /8 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... Tonight... Models are indicating a wave developing on the front this evening and tracking south of New Eng which will likely allow showers to persist well into the evening across SE New Eng and Cape/Islands. Otherwise, improving conditions tonight from west to east as deep moisture and PWAT plume move to the east. Areas of low clouds and patchy fog expected, especially in eastern New Eng. Lows will be mostly in the 60s. Wednesday... Low pres SE of New Eng will gradually pull away, but the northerly flow along the coast and lingering low level moisutre may keep areas of lower clouds persisting through the morning across eastern MA. Otherwise, partly to mostly sunny skies expected in the interior with increasing sun during the afternoon in the east. Models are generating marginal instability late in the day in the west with CAPEs 500-1000 J/kg. A few showers or an isolated t-storm is possible late in the day across western and central MA as another shortwave approaches from the west. 850 mb temps 15-16C will translate to highs into the upper 80s in the CT valley and 80-85 across the rest of SNE away from the coast. Cooler 925 mb temps noted in eastern MA which should keep temps in the 70s in east coastal MA as sea breezes develop. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Big Picture... Zonal flow over the Northeast USA through Friday. Broad upper ridge over the Southern USA builds north through the Plains late in the week, then shifts east early next week. Large closed low lingers over the Pacific Coast through Friday, then ejects northeast into Canada over the weekend. This ejecting low kicks another low away from Hudsons Bay. The Hudsons Bay upper low sweeps southeast to New England by Sunday and to our east Monday. The remnants of the Pacific upper low moving southeast out of Ontario Tuesday. Contour heights from 500 mb will be above normal through Saturday. Heights then lower to the low side of normal Sunday-Monday as the Hudsons Bay upper low sweeps across New England. Heights return to seasonable levels Tuesday-Wednesday. Expect above normal temperatures Thursday to Saturday, cooler Sunday-Monday, then warming again Tuesday-Wednesday. Forecast confidence is moderate-high. The various model mass fields are similar through Sunday morning. They agree on the general pattern after that through Wednesday, but with differences in handling the departing upper low Sunday and the following shortwave over Ontario Tuesday. Concerns... Thursday-Friday... Two shortwaves move through the flow during this period. The GFS brings them through Thursday night and Friday night while the ECMWF shows just one passage on Thursday night. Moisture is limited to the 700-850 mb layer with plenty of dry air above. This would suggest shallow clouds. The supporting upper jets with the shortwaves mostly aim their favorable dynamics north of the Mass border, directing most cloud development there. PW values top out 1.0 to 1.25 inches Thursday, drop back, then resurge to 1.5 inches Friday night. Expect mainly dry weather Thursday, but with diurnal clouds developing, either cumulus or alto-cu. SBCAPES are forecast around 500 mb along the NH border. Total-totals show a similar favoring of VT/NH. Scattered or widely scattered afternoon showers should form, with placement favoring northern Mass. Could be isolated thunder as well. Mixing will reach between 800-850 mb, which will tap equiv 850 temps of 14-16C. This supports max sfc temps in the 80s. Friday should be dry during the day, but expect scattered showers with the Friday night shortwave. Most of these should develop in Upstate NY in the afternoon and move into our area Friday evening or Friday night. The SREF shows a 50 pct chance of CAPE over 1000 in CT and Western MA Friday evening, so we will mention some thunder as well. Temps aloft support 80s again, possibly around 90 in some spots. Saturday... Upper low from Hudsons Bay drives southeast, aided by a 100-kt upper jet. This drives a cold front southeast across New England Saturday afternoon and night. The cold front provides a source of low-level convergence, the upper jet provides dynamic support, and daytime heating generates instability. CAPE of 1000-1500 J/Kg and totals near 50 are forecast. So we expect showers/thunder to develop. Mixing is not expected to go as deep as previous days, but should still reach 850 mb, where temps will be around 15C. So max temps will again be well into the 80s. Sunday... Surface cold front moves south of New England, while the upper low/cold pool/cold pool moisture move south across Southern New England Sunday. With the colder air moving in aloft, expect to around 850 mb and possibly near 800 mb. The cold pool moisture should be enough to generate clouds, and stability parameters support showers and scattered thunder. Temperatures at 850 mb will be 10-11C, supporting max sfc temps 75 to 80. Monday-Tuesday... The uppper low pulls east Monday, taking much of the cloud cover and showers. Another cold front may dive out of Canada Tuesday night, bringing another chance of showers. && .AVIATION /20Z TUESDAY THROUGH SUNDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday Night/...Moderate confidence. 1815z update ... Thru 00z ... high confidence on trends, lower on exact details. Showers with embedded thunder and heavy rain over southeast CT will hold together and may intensify as it moves across RI and southeast MA thru 21z. Lowest cigs/vsbys will accompany this activity. After 00z ... high confidence on trends, lower on exact details. Any heavy showers with embedded thunder at 00z should be confined to Cape Cod and the Islands. A second but smaller area maybe over CT but both areas will be trending downward/weakening. Then next area of interest will be areas of dense fog in IFR/LIFR along the south coast. Wednesday ... high confidence. Patchy MVFR/IFR cigs/vsbys in the morning across portions of east coastal MA, otherwise VFR. Chance of a late day shower/t-storm across western MA/CT. Wednesday night ... Scattered showers and T-storms over eastern NY at 00z may hold together and enter western-central portions of MA/CT but slowly weaken as well. KBOS Terminal...heavy showers and embedded thunder over southeast CT at 18z may stay mainly south of Logan but will be a close call through 21z/22z KBDL Terminal... High confidence in trends. Lower confidence in specific details and timing. Outlook /Thursday through Sunday/...Moderate confidence. Thursday through Friday: VFR. Friday Night: Mainly VFR, with areas MVFR possible. Chance SHRA, isolated TSRA. Saturday: Mainly VFR, with areas MVFR possible. Chance SHRA, chance TSRA. Saturday Night: Mainly VFR, with local IFR possible. Chance SHRA, slight chance TSRA. Sunday: Mainly MVFR, with areas VFR possible. Breezy. Chance SHRA, chance TSRA. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday Night/...High confidence. Winds and seas below SCA thresholds through the period. However, southerly gusts may reach 20+ kts this afternoon and evening as a low level jet moves across the waters. Light northerly winds Wed becoming onshore in the afternoon as sea breezes develop. Vsbys reduced this afternoon and evening in showers and fog. Isolated t-storms possible. Patchy fog may linger into Wed morning across eastern and SE waters. Outlook /Thursday through Sunday/...Moderate confidence. Thursday through Thursday Night: Winds less than 25 kt. Local visibility 1 to 3 nm. Seas less than 5 ft. Friday: Winds less than 25 kt. Seas less than 5 ft. Friday Night: Winds less than 25 kt. Seas less than 5 ft. Slight chance of rain showers. Saturday: Winds less than 25 kt. Seas less than 5 ft. Slight chance of rain showers, slight chance of thunderstorms. Saturday Night: Winds less than 25 kt. Seas less than 5 ft. Chance of rain showers, slight chance of thunderstorms. Sunday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers, chance of thunderstorms. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...WTB/KJC/Nocera NEAR TERM...Nocera SHORT TERM...KJC LONG TERM...WTB AVIATION...WTB/Nocera MARINE...WTB/KJC