textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

- A few showers early this morning, then more widespread showers move through SNE this afternoon into early evening associated with a cold front.

- Clearing and colder overnight, then blustery Monday.

- Could see a few rain/snow showers Monday night into Tuesdaymorning, but otherwise expecting cooler temperatures and dry weather for a good portion of next week.

- Second half of next week looks mainly dry with temperatures on the rise.

DISCUSSION

KEY MESSAGE 1...A few showers this morning, then more widespread showers move through SNE this afternoon into early evening associated with a cold front.

The backdoor front which moved through SNE Saturday will return northward as a warm front later this morning. Modest low level jet combined with marginal elevated instability will bring a few showers this morning and possibly a rumble of thunder. Lots of stratus and fog also expected this morning with abundant low level moisture trapped within a strong surface inversion. The fog should lift later this morning and afternoon as SW flow develops but stratus may linger as low level moisture is persistent. The surface inversion eventually erodes in the afternoon but mixed layer is quite shallow. This combined with cloud cover and showers will limit how mild it gets, expecting highs reaching upper 50s and lower 60s, but cooler along the south coast. It will also be breezy over the Cape/Islands with low level jet across the region, expecting gusts to 35 mph at times.

We expect a period of widespread rain moving west to east across SNE during the afternoon as a cold front moves through. The cold front will be accompanied by a deep moisture plume with PWATs 1-1.5" and right entrance region of upper jet so a period of widespread showers is likely. Marginal elevated instability is also present so can't rule out an isolated t-storm. The bulk of the showers should end by late afternoon, but will linger into the evening across SE MA and Cape/Islands with later timing of cold front.

KEY MESSAGE 2...Clearing and colder overnight, then blustery Monday.

Cold front moves across the Cape/Islands in the evening then offshore overnight. The frontal passage will be followed by clearing and colder conditions and it will become blustery overnight in the cold advection pattern. Lows will drop into the 30s. Blustery but dry weather continues Monday with soundings showing a deepening and well mixed boundary layer supporting gusts to 35 mph at times. Diurnal cu will develop as upper trough and cooling temps aloft move through. Highs will range from the upper 40s to lower 50s which is near or slightly below normal for early April.

KEY MESSAGE 3...Could see a few rain/snow showers Monday night into Tuesday morning, but otherwise expecting cooler temperatures and dry weather for a good portion of next week.

Expecting an upper-level trough to push across the Great Lakes and into New England early next week, leading to mostly dry weather and cooler temperatures. Ensemble guidance is indicating 850mb temperatures could get to below -5C and 500mb temperatures below - 30C Tuesday as a shortwave moves through, which would support some light snow showers developing and mixing in with rain showers, especially over the higher elevation areas, though we're not expecting any road or travel impacts. Surface temperatures will likely hover near or possibly just below freezing Monday night into Tuesday morning, but they're expected to make a fast recovery later Tuesday morning... into the mid 40s. Otherwise, dry weather with high temps mainly in the middle 40s to the lower 50s and overnight temperatures ranging from the mid 20s to mid 30s through Wednesday night.

KEY MESSAGE 4...Second half of next week looks mainly dry with temperatures on the rise.

A large high pressure system moves into the Mid-Atlantic region by the second half of next week, bringing predominantly southwesterly flow and dry conditions back to southern New England. The warmer airmass advecting into the region will allow temperatures to recover back into the 50s and 60s by the end of the week.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

Forecaster Confidence Levels...

Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.

12z TAF Update:

Today: Moderate confidence.

Conditions lowering to IFR-LIFR in developing stratus and fog early this morning. Vsbys improve some later this morning but low cigs will persist through today. A few showers possible this morning, then more widespread rain and isolated thunder move through from W to E this afternoon. Wind shift to S then SW occurs 12-15z from S to N with gusts to 25-30 kt developing along the south coast and Cape/Islands. Areas of LLWS associated with the low level jet.

Tonight: High confidence.

Lingering IFR-MVFR in showers over SE MA and the Cape/Islands in the evening, otherwise becoming VFR with clearing skies from W to E. NW wind 10-15 kt with gusts to 20-25 kt developing overnight.

Monday...High confidence.

VFR. NW gusts to 25-30 kt.

KBOS Terminal...High confidence in trends but moderate on timing. Expect conditions to lower to LIFR in stratus and fog after 09z with vsbys improving by 15z after wind shift to SW. IFR cigs likely persist although may see some improvement to low end MVFR this afternoon. Improving to VFR with wind shift to NW after 00z.

KBDL Terminal...High confidence in trends but moderate on timing. Lowering cigs and vsbys to IFR-LIFR, improving to VFR with wind shift to NW 23-00z.

Outlook /Monday Night through Thursday/...

Monday Night: VFR. Chance SHRA, chance SHSN.

Tuesday: Breezy. Chance SHRA, chance SHSN.

Tuesday Night: Breezy.

Wednesday through Wednesday Night:

Thursday: Breezy.

MARINE

Forecaster Confidence Levels...

Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.

High confidence.

Gusty pre-frontal SW winds today with gusts to 25-35 kt as LLJ will be over the waters. Will continue SCA although a few near gale force gusts possible. The LLJ moves offshore tonight but expect post- frontal W gusts to 25 kt late tonight and Monday. Areas of fog this morning with poor vsbys, then showers mid afternoon into this evening. An isolated t-storm is possible.

Outlook /Monday Night through Thursday/...

Monday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers.

Tuesday: Winds less than 25 kt. Chance of rain showers.

Tuesday Night: Winds less than 25 kt. Seas locally approaching 5 ft.

Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft.

Wednesday Night: Winds less than 25 kt. Seas locally approaching 5 ft.

Thursday: Winds less than 25 kt. Seas up to 5 ft.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ230>234-236-251. Small Craft Advisory until 2 AM EDT Monday for ANZ235-237. Small Craft Advisory until 2 PM EDT Monday for ANZ250. Small Craft Advisory until 8 PM EDT Monday for ANZ254>256.