Area Forecast Discussion
Issued by NWS Boston, MA
Issued by NWS Boston, MA
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953 FXUS61 KBOX 131730 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 130 PM EDT Mon May 13 2024 .SYNOPSIS... Mainly dry conditions today and turning milder with more seasonable temperatures as high pressure builds to the south. A warm front will bring scattered showers tonight followed by warm weather Tuesday, but a few showers are possible in the interior during the afternoon. A coastal storm lifting NE from the middle Atlantic coast may bring showers and cooler temperatures Wednesday, and unsettled weather could linger into Thursday as the low pressure is slow to depart. High pressure returns Friday then another system may bring more rain next Saturday. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Update: 9:30AM Areas of patchy fog in western Massachusetts and northwest Connecticut have lifted, now wall-to-wall sunshine across majority of southern New England thanks to surface high pressure. Temperatures already are in the middle and upper 50s and are on track to reach the upper 60s and low 70s away from the coast. Forecast remains in good shape with no changes. See previous forecast discussion below. Shortwave ridging moves into New Eng today with surface high pres south of New Eng. Dry air in the column to start the day will result in lots of sunshine this morning, then clouds will increase during the afternoon as warm advection increases ahead of an approaching warm front. A modest low level jet transports higher PWATs into New Eng from the west during the afternoon which may lead to a few showers in western MA mid-late afternoon, otherwise dry weather today. The S-SW flow will bring a milder airmass into SNE as 925 mb temps increase to 10-12C. Highs should reach the upper 60s to lower 70s, but cooler along the immediate coast where sea-breezes develop. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... Tonight... Warm front will be moving into SNE tonight with PWATs increasing to 1-1.25". Deepening moisture plume ahead of the front moves across the region 00-06z which will bring scattered showers, especially north of the Pike where best forcing sets up. Then dry slot moves in behind the front 06-12z so shower activity will exit to the north and east overnight. S-SW winds and higher dewpoints advecting into the region will result in a milder night with lows upper 40s to lower 50s. Tuesday... Warm sector airmass overspreads SNE on Tue with warm and somewhat more humid airmass. Some stratus is possible across northern MA to start the day, otherwise expect partly to mostly sunny skies with clouds increasing later in the afternoon. 925 mb temps increase to 15-17C supporting highs 75-80, perhaps a few lower 80s in the interior valleys, but 60s near the south coast due to increasing S- SW flow. Dewpoints will be climbing through the 50s. It will become breezy with soundings suggesting gusts to 20-30 mph in the afternoon. Marginal instability across the interior which may lead to a few convective showers developing mid-late afternoon, but better chance of showers and t-storms will be to the north and west where better moisture and instability closer to a frontal boundary. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... Key Points * Rain possible Wednesday with showers lingering into Thursday * Mainly dry Friday, then unsettled wet weather returns for the weekend. * High temps remain seasonable with onshore flow Wednesday Shortwave trough exits out of the Ohio River Valley and passes just south of SNE. With the best forcing to the south, this has caused models to trend the associated surface low further south. This shift south has been a trend with guidance over this time range in the last week. Wouldn`t be surprised if models keep shifting the low and QPF south over the coming days. With the shift south, Ensemble QPF probs have decreased significantly. Probs for 1 inch of rain is now less then 10% and for 0.5 inches less then 30%. High temps drop back into the mid to upper 60s with 850mb temps dropping back to +7C along with showers and thick cloud cover around much of the day. Thursday and Friday Guidance has trended slower kicking out the shortwave as it tries to cutoff over the mid Atlantic coast due to downstream blocking. This has resulted in rain chances lingering into Thursday before an abnormally dry airmass and NW flow kicks in for Thursday afternoon into Friday. High temps both days should reach the upper 60s to mid 70s with mainly sunny conditions and onshore flow. The only wrench in a nice pleasant end to the week is if the cutoff stalls just south of the region which would bring cooler temps, cloudy skies, and more rain. Winds Thursday could become gusty up to 35mph esspically near the coasts as the surface low passes offshore to the east. Next Weekend Another shortwave trough exits the Great Lakes Saturday into Sunday. Guidance remains quite spread on the timing and amplitude of this shortwave. There will likely be rain sometime over the weekend, but its too early to pin down exact timing and how much will fall. Highs over the weekend look to remain seasonable in the upper 60s to mid 70s with onshore flow. && .AVIATION /17Z MONDAY THROUGH FRIDAY/... Forecast Confidence Levels: Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Through 00z...High confidence. VFR, 4-7k ft CIGs. A rouge shower is possible in far western MA and NW CT, otherwise dry runways. Sea-breeze along the coast will continue until 23z/00z, from there wind shifts to the south. Elsewhere, winds are south to southwest 10 to 15 knots. Tonight...High confidence. VFR. Scattered showers are possible across northern MA, with at times briefly lower VFR CIGs 3-5k ft. Winds are south to southwest 5 to 10 knots. Tuesday...High confidence. VFR. A few convective showers possible across interior MA and northern CT during the afternoon. Steady southwest winds with gusts developing in the afternoon 20 to 25 knots. Tuesday Night...Moderate confidence. VFR to start, becoming MVFR/IFR heading later into the night with increasing rain chances from west to east. Southwest winds 8 to 12 knots early, becoming south 5 to 10 knots. KBOS TAF...High confidence in TAF. VFR. Sea-breeze continues this afternoon, becoming a southerly wind after 23z. A brief shower or two is possible overnight, opt to include a PROB30 for -SHRA between 07z/09z. For Tuesday, most of the daylight hours are dry, breezy southwest winds with gusts 20 to 25 knots. Rain chances increase Tuesday night. KBDL TAF...High confidence in TAF. VFR. Light south-southwest winds today and into tonight. Increasing wind speeds Tuesday with gusts 20 to 25 knots possible. Dry for most of Tuesday as well, rain arrives after 00z. Outlook /Tuesday Night through Friday/... Tuesday Night: MVFR/IFR conditions possible. Breezy. Chance SHRA. Wednesday: Mainly MVFR, with areas IFR possible. Breezy. SHRA likely. Wednesday Night: MVFR/IFR conditions possible. Breezy. Chance SHRA. Thursday through Thursday Night: Mainly VFR, with local MVFR possible. Breezy. Slight chance SHRA. Friday: Mainly VFR, with local MVFR possible. Slight chance SHRA. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Through Tuesday... Increasing S-SW winds this afternoon into tonight with gusts to 20 kt at times over nearshore waters. SW gusts to 25 kt Tue, especially eastern MA waters where SCA will likely be needed. Outlook /Tuesday Night through Friday/... Tuesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers. Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers. Wednesday Night: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Chance of rain showers. Thursday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Chance of rain showers. Thursday Night: Winds less than 25 kt. Seas up to 5 ft. Slight chance of rain showers. Friday: Winds less than 25 kt. Seas up to 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...KJC/KP NEAR TERM...KJC/Dooley SHORT TERM...KJC LONG TERM...KP AVIATION...Dooley/KP MARINE...KJC/KP