textproduct: Boston / Norton

WHAT HAS CHANGED

Increased high temperatures a few degrees above model guidance through the middle of the week.

KEY MESSAGES

- Dry and unseasonably mild into mid-week with highs mainly in the upper 60s to the lower 70s. Some spots may reach into the middle 70s for a day or two and challenge record highs.

- Pattern becomes more unsettled late-week into the weekend featuring periodic chances for rain.

DISCUSSION

KEY MESSAGE 1...Dry and unseasonably mild into mid-week with highs mainly in the upper 60s to the lower 70s. Some spots may reach into the middle 70s for a day or two and challenge record highs.

An anomalous upper level ridge of high pressure will be in control of our weather through the middle of the week. The result will be continued dry weather with unseasonably mild temperatures. Given the extended period of dry weather...MOS guidance is likely a few degrees too cool during the afternoons and we have increased. Afternoon high temperatures will mainly be in the upper 60s to the lower 70s...although a few degrees cooler for the Cape/Islands. In fact...925T rising into the +11C to +15C range will potentially allow for some locations to reach the middle 70s especially towards mid-week and challenge record high temps. The main uncertainty on temperatures will revolve around the amount of mid-high level clouds that spill into the region at times. Regardless...high confidence in continued dry weather with unseasonably mild temperatures through the middle of the week.

KEY MESSAGE 2...Pattern becomes more unsettled late-week into the weekend featuring periodic chances for rain.

Ensemble guidance shows a consensus in a shift of the pattern late Thursday into Friday as a mid-level trough arrives from the west. This will advect in a plume of rich moisture 2-3 standard deviations above normal. This will be accompanied by a frontal system that pushes across the Ohio River Valley and into the Mid-Atlantic and Northeast. This will likely bring us our next best shot at precipitation. Details such as timing, rain amounts/rates are still lower confidence due to uncertainty in the tracking of the surface features/best forcing. If the frontal features track closer, this could put southern New England in better forced environment and potentially with marginal instability present. This could favor a few rumbles of thunders or heavier downpours. Timing of this is low confidence due to the track uncertainties, but the general timeframe is late Thu through Sat. Lighter/spotty showers may linger at late as Sunday. However, it likely won't be rain for the entire timeframe.

Ensemble guidance highlights probabilities of 30-60% for rain totals of 0.50" or more and low probabilities (10-30%) for 1.0" or greater. Deterministic solutions have leaned toward the upper percentile solutions of their ensemble suite showing potential for amounts 1.0 to upward of 2.0" inches. Once guidance comes into better agreement, confidence will increase in the exact timing of rainfall and totals.

Above normal temperatures are likely Thursday with the mid-level thermal ridge shifting over southern New England with 925mb temperatures +13-15C. This will support high temperatures in the upper 60s to low/mid 70s! Temperatures likely lean seasonably warm for Friday as well. Depending on how the system tracks, we may get one more day of milder temperatures Saturday with more seasonable temperatures arriving by Sunday.

AVIATION /00Z MONDAY THROUGH FRIDAY/

Forecaster Confidence Levels...

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

00z TAF Update...High confidence.

VFR conditions will continue through the middle of the week with some mid-high level cloudiness at times. Winds will generally average from the SW at 5 to 15 knots during the afternoon/s.

KBOS Terminal...High confidence in TAF. Some gusts near 20 kts are possible Monday afternoon.

KBDL Terminal...High confidence in TAF.

Outlook /Wednesday Night through Friday/...

Tuesday through Tuesday Night: VFR.

Wednesday: VFR. Breezy.

Wednesday Night: VFR.

Thursday: VFR. Breezy. Slight chance RA.

Thursday Night: VFR. Chance RA.

Friday: Mainly VFR, with local IFR possible. RA likely, slight chance TSRA.

MARINE

Forecaster Confidence Levels...

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

Tonight through Wednesday...High confidence.

An upper level ridge of high pressure will keep winds/seas below small craft advisory thresholds through the middle of the week. Nonetheless...we may have some SW wind gusts of 20+ knots at times particularly nearshore during the afternoons. This may result in some choppy seas at times...but thinking we should remain below the need for headlines.

Outlook /Wednesday Night through Friday/...

Tuesday through Thursday: Winds less than 25 kt.

Thursday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain.

Friday: Winds less than 25 kt. Seas up to 5 ft. Rain likely.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...None.