Splendid Sun to Incoming Shot of Rain, Building Ocean Swell

LKS_FRONTS_BOSDMA (5)Delightful, early September weather brings  a low-stress return to post-Labor Day school and work routines, at least when it comes to weather impacts!  Crisp, cool mornings in the 50s (40s in Northern valleys) and daytime highs either side of 80° with low humidity make it possible for One and All to enjoy comfort outside, with the only exception being for ragweed pollen allergy sufferers, as the pollen count remains high.  With our progression to fall, the sun angle isn’t as strong as it was in the summer, so even unabated Tuesday and Wednesday sun will deliver a high, not very high, ultraviolent index – enough for sunburns with prolonged exposure, but not the intensity of mid-summer.  For many coastal residents, the day after Labor Day is a favorite day of the year – summer visitors have returned home and there’s plenty of space on the sand to go around…enjoy the midday high tide and one to two foot waves Tuesday, as our First Alert Team expects ocean swell to build a bit on Wednesday with a slightly elevated rip current risk, then more significant swell of four to eight feet with a strong rip current by Thursday and Friday as Hurricane Larry zips east of Bermuda and into the Canadian Maritimes.  As for the skies, expect a strengthening south wind Wednesday to boost temperatures into the 80s all the way to the Canadian border, but an approaching cold front will trigger building clouds and incoming thunder to Western New England by Wednesday evening into night – some of those storms may be strong.  Farther east, storms will slowly arrive from the west while weakening overnight Wednesday night, then the instigating cold front will likely slow to a crawl Thursday, meaning recurring pockets of rain and embedded downpours are in the forecast for Eastern New England Thursday with either side of an inch of rain, and our weather team has issued a First Alert for Thursday, expecting an impact to one or both of the Thursday commutes.  By Friday, the cold front eases off our coast, leaving only a very slight chance of a shower Friday but most of us will see great improvement, en route to another shot of dry, comfortable air with plentiful sun just in time for the upcoming weekend!  Although a couple of disturbances show up in our forecast next week for an increased chance of showers both Monday and Wednesday, both systems look to be fairly quick-moving right now, so the exclusive First Alert 10-day forecast certainly shows more dry days rather than wet ahead!


Lovely Tuesday Ahead of Ida's Flooding Rains for New England and the Northeast

LKS_FRONTS_BOSDMA (4) LKS_FRONTS_BOSDMA (4) LKS_FRONTS_BOSDMA (4)Ida is no longer a hurricane…or a tropical storm…or a tropical depression…but does still represent a slug of rain and a low pressure center – a storm center – churning northeast, dumping flooding rain along its path and heading for New England.  In the interim, humidity has decreased Tuesday behind a cold front that swept off our New England coast in the predawn hours and brought a wind shift to open the door to more comfortable air from Canada and the Great Lakes, so high temperatures returning to the 80s for a second day in a row feels decidedly different than Monday with dew point temperatures – the measure of the amount of moisture in the air – dropping from the 70s to the 50s.  The drier, more comfortable air will hold rain at bay for awhile, but the wealth of tropical air streaming north ahead of Ida’s remnant center will first bring high-altitude clouds Tuesday, then thickening clouds Tuesday night into Wednesday, then developing showers from southwest to northeast across Southern New England Wednesday morning to afternoon, then an all-out rain Wednesday night through Thursday.  With the heaviest, tropical downpours expected between midnight Wednesday night and midday Thursday, total rain amounts near and south of the MA Turnpike likely will reach two to four inches with localized flooding – urban, street, stream and some small river flooding – and Flash Flood Watches have been hoisted in this area.  Although amounts may be a bit less north of the Pike, much of Central New England should still see a one to two inch rainfall with much less in Northern New England, and almost nothing in the far North Country.  With the counter-clockwise swirl of air associated with the storm center passing to our south, most of New England will find a gusty north-northeast wind Thursday as Ida’s remnant center finds some renewed strength over the ocean waters to our south, meaning gusts of 35 to 50 mph are possible Thursday, especially near the coast.  If the storm center moves a bit farther north, the wind may turn to blow from the south over Cape Cod and increase the chance for severe thunderstorms, too,, but that’s not extremely likely at this point.  By Thursday late day and evening, rain will taper to showers and a burst of drier air is expected by Friday, so while some scattered mountain showers may pop up Friday, most of New England will start drying out, en route to a great weekend of fair, pleasant weather.  Labor Day Monday is likely to bring a push of slightly warmer air – around 80° for many – ahead of an approaching disturbance that will deliver scattered afternoon and evening thunder with an attendant cold front, and a similar pattern may repeat again for the middle of next week in our exclusive, First Alert 10-day forecast.


Saturday Midday Update on Hurricane Henri's Approach to New England

The following is a compilation of tweets from today (Twitter account @MattNBCBoston)  I've assembled into a post for an update on impending Henri:

Good afternoon, friends - I'm on

this afternoon with our #FirstAlert Team's updated look at #Henri and my biggest message, by far, has been clear: all of Southern New England should remain on guard for a potential hurricane.


LKS_HENRI_DAY1OVERVIEWYou'll notice in the wind damage potential map I'm airing on

, I've taken nobody off guard - and there's good reason. Even based on the current NHC track, which I think may shift east, check out their forecast chance of tropical storm wind (39+ mph) capable of damage.

LKS_HENRI_WINDDAMAGE
LKS_HENRI_WINDDAMAGELooking at satellite imagery, the steering flow aloft, and the trend in available guidance, a shift eastward in track to somewhere between New London CT and Buzzards Bay MA remains very much in play. Note how that would change the expected wind field.

LKS_TROPICS_WINDGUST_MODEL

 

While chance of Tropical Storm force wind is high for many in Southern New England, even in the official NHC package which may end up needing further eastward adjustment, chance of hurricane (sustained 74+) is limited, but again, corridor may come east & this is not gusts.

Storm surge stakes are incredible. If an eastern track near Narragansett or Buzzards Bay goes up, these surge numbers skyrocket on the north end of the bays. Exactly why I'm strongly suggesting all involved in planning/response be ready to active rapidly in these next 24 hours.

LKS_TROPICS_SURGEMarine and Coastal Communities: Please remain vigilant and ready for a track forecast that may shift east. This storm track is not certain and you absolutely should not rely on the western track yet. Out of respect for inherent uncertainty, keep staffing up for now.

LKS_HENRI_PREPS_COASTAL (1)Power Outages: If a western track into CT verifies, widespread outages CT/RI and into Western MA, scattered farther east. If an eastern track verifies, widespread outages Central/Eastern MA, RI, SE NH. Hence, all of Southern NewEng should remain prepped for extended loss of power

LKS_HENRI_PREPS_OUTAGES (1)Two big reasons a more eastern scenario is still in the cards: satellite imagery shows steering wind pointing due north, west track hinges on sudden shift in steering wind. 2) here's best performing guidance overlaid on current forecast cone. Center or east of cone center.

LKS_TROPICS_SPAGHETTI_PREFERREDWhile official gov't forecast has undoubtedly shifted dramatically over time westward, now coiling back east, NHC is always very clear: look at the cone, not the track. Messaging of that gets lost often. Final track well may be in a spot that was in cone for several forecasts.

Heaviest rain will fall near and west of the storm track. Of course, that means it can deviate depending on what the actual storm track is, but the general idea is Central/Western New England get hit hardest with flash flooding, river flooding that follows as water runs off.

LKS_PRECIP_FCST_NEWENG
LKS_PRECIP_FCST_NEWENGRe: #Henri - I do like the fact that the surface circulation is running ahead of the deep thunderstorms, you can see that on satellite, the big, beefy storms are SE of the clear spiral. *If* it doesn't generate new ones, that can often lead to some modest weakening over time.

Satellite


Henri Takes Aim at New England - Could Be First Direct Hurricane Hit in 30 Years

LKS_HENRI_PREPS_GENERAL LKS_HENRI_PREPS_GENERAL LKS_HENRI_PREPS_GENERAL LKS_HENRI_PREPS_GENERAL LKS_HENRI_PREPS_GENERALHurricane Watches have been hoisted across New England and, depending on the exact strength at landfall, New England may be staring down the barrel of the first direct hurricane strike to our coast since Hurricane Bob in 1991.  We’ve seen plenty of tropical storms, decaying hurricanes and nor’easters, but a storm of this magnitude, making a direct strike as a hurricane, hasn’t come calling in 30 years.  So, it’s all eyes on Henri as the Tropical Storm is predicted to strengthen to a hurricane strength as it drifts from a position south of Bermuda to a location squarely over the warm waters of the Gulf Stream – the warm current of ocean water off the Eastern Seaboard that favor storm strengthening.  If the storm follows the latest official track and intensity from the National Hurricane Center, it will landfall along the South Coast of New England as either a strong tropical storm or minimal hurricane, with widespread wind damage and power outages, flooding rain, coastal flooding due to high tide and storm surge and significant loss of property due to storm surge along New England’s South Coast can be expected.  Conditions are expected to deteriorate rapidly Sunday morning – after two relatively benign days Friday and Saturday.  With lots of clouds and an occasional shower Friday, humidity continues but will build even more Saturday as a light southeast wind begins, carrying truly tropical air into New England ahead of the strengthening storm to our south.  As dew point temperatures rise and the moisture content of the air increases, sunshine will give way to building clouds and scattered afternoon tropical showers – still innocent enough.  Clouds increase Saturday night and problems compound Sunday as the southeast wind strengthens across Southern New England early in the morning.  With rip currents gradually building at New England beaches over the weekend, beachgoers will need to exercise caution, particularly with kids.  Henri will waste no time Sunday, with bands of rain and gusty wind arriving to Southern New England by early to mid-morning and conditions will rapidly deteriorate over the morning to midday.  By Sunday afternoon, rounds of damaging southeast wind will be impacting most of Eastern MA and RI, with a northerly wind on the west side of the storm track, currently predicted to be into Western RI but with a cone of probability that includes possible tracks anywhere into the South Coast.  Gusts may exceed 90 mph at exposed coastal locales, and will top 50 mph for many on the east side of the storm track.  For comparison, power outages from Hurricane Bob lasted more than a week for some, so all residents of Southern New England, southeast NH and coastal ME should check generators and start making preparations for extended outage potential.  Storm surge will be worst near where the eye of the storm comes ashore, so all areas along New England’s South Coast should make preparations for areas of inundation and damaging, surging waves that will result in evacuations for some vulnerable spots.  The Eastern coast of New England is also subject to coastal flooding owing to the strong onshore wind, and those who own boats should follow your marina or Harbormaster’s suggestions, as each locale will respond a bit differently based on the slope of the coast and direction of the wind.  Rainfall of at least three to five inches with locally in excess of half a foot will result in pockets of flash flooding Sunday afternoon and night, with both small and mainstem rivers rising Sunday night into Monday and river flooding a concern as the rain runs off into the river basins.  In a situation like this, residents both at the coast and inland should follow the advice of local emergency managers, who reference well-studied research when suggesting or ordering evacuations.  At this point, we are hoping for a weaker storm or an altered storm track, but the window for that is closing and New England must make preparations for the most likely outcome, described here.  The storm will weaken with gusty rain lingering Monday but drift east to the Gulf of Maine and sun returns Tuesday.


As Remnant of Tropical Storm Fred Approaches, Henri Raises The Stakes for New England

LKS_WEEKEND_PRECIP_ACTIVE LKS_WEEKEND_PRECIP_ACTIVE LKS_WEEKEND_PRECIP_ACTIVE LKS_WEEKEND_PRECIP_ACTIVEWhat has been casual observing of the busy Tropical Atlantic for several days has become active forecasting for our First Alert Weather Team.  First, the remnant moisture of once-Tropical Storm Fred has been expanding across the Northeast and while most of the rain Wednesday is focused from the Appalachian Mountains to Pennsylvania and Upstate New York, showers and periods of rain are expanding east across Northern New England, while an occasional shower will impact Southern New England Wednesday, particularly during the afternoon.  With a steady south and southwest breeze, humidity is on the rise Wednesday and even with plenty of clouds and only breaks of sun, temperatures are rising into the 80s.  While more downpours join the showers in Northern and Central New England overnight Wednesday night, the bulk of New England’s rain will fall Thursday, expanding from west to east during the morning, arriving to the Cape and Eastern Maine last, around midday and afternoon, respectively.  Our weather team has issued a First Alert for potential impact of downpours and thunder Thursday, slowing travel and perhaps resulting in localized flooding, particularly in parts of Northern and Western New England.  Showers and downpours will break into scattered form later Thursday, with Friday likely to bring a relative break in the action with only a few showers but breaks of sun and humid air bumping temperatures to 85-90 degrees during the afternoon!  The next storm approaching New England brings an increasing chance of showers Saturday, especially during the afternoon, while humid air persists all the way into next week.  The biggest issue in our forecast focuses on the Sunday/Monday timeframe, when Tropical Storm Henri, south of Bermuda on this Wednesday morning, is predicted to strengthen to a hurricane over the warm Gulf Stream waters and turn northward, paralleling the East Coast.  The key to our Sunday and Monday forecast hinges on how our incoming storm from the west interacts with Henri.  The most likely outcome is for Henri to get a bump toward the northeast as our storm approaches, causing the Hurricane to deflect out to sea to our southeast but likely throw building swell into our coastal waters and a rip current to our beaches.  If our incoming storm is slow enough…and just the right strength…it will fail to boot Henri out to sea and instead the two systems may merge, pulling the hurricane close to or perhaps even over New England.  Although this worst-case scenario is unlikely at this point, it’s not impossible, and that’s why both Chatham and Nantucket are in the forecast cone of probability from the National Hurricane Center for a possible center-passage Sunday into Monday.  For now, our First Alert forecast acknowledges this potential but follows the most likely scenario of building seas to 4-6 feet, strengthening beach rip currents, rain due to the incoming storm from the west, but a passage of Henri and its wind core to our southeast.  Regardless, humidity will linger until midweek next week in our exclusive First Alert 10-day forecast.


Heat and Humidity Set to End In Saturday Storms

10_DAY_ACTIVE 20210813Another hot and uncomfortable day with 100°+ heat indices is unfolding in New England.  A disturbance aloft may touch off a few showers and thunderstorms late Friday or early Friday evening in Southern New England, and while there’s only a 20% chance from Springfield to Worcester, Providence, Boston and surrounding suburbs, any storm that develops would feed off heat and humidity to potentially become strong.  The next disturbance arrives from New York State traveling east later Friday evening into the night, from west to east across New England, respectively, with thunder and showers that may last into the early morning Saturday in Eastern New England.  Although any scattered morning showers Saturday will tend to abate for enough hours around late morning and midday for breaks of sun to push temperatures into the 90s in Southern New England and 80s north, new showers and thunder will fire in Northern and Western New England during late morning and midday, slowly expanding south and east during the afternoon, arriving last to Cape Cod as an evening round of thunder.  These storms will be developing ahead of a strong cold front that overturns our hot and humid air, culminating in a Saturday of heat index values in the middle 90s in Southern New England before a north wind takes hold and ushers much less humid air into all of New England Saturday night.  Sunday will feel splendid – lower humidity, cooler air with highs near 80, sunshine north and sunshine muted by high-altitude clouds but a dry day, nonetheless, south.  In fact, phenomenal air continues through the first half of next week in our exclusive First Alert 10-day forecast until warmer, more humid air and a chance of showers returns for week’s end into next weekend as remnant moisture from Tropical Storm Fred – set to hit Florida this weekend then slowly drift north through the Eastern U.S. – may drift into New England.


Heat and Humidity Only Increase Thursday...But an End Is In Sight

LKS_BOARD_PIC_WITH_TEXT (1)Our First Alert rolls on through Thursday and Friday as heat and humidity continue to couple for weather that takes a toll on the body.  Heat stress on the body can be cumulative, day after day, particularly for those without air conditioning whose bodies never really get to recuperate with warm and sticky nights.  Coming off a night where the heat index in Boston only slipped below 80° for a couple of predawn hours and with a day predicted to deliver highs in the middle 90s with widespread heat index values of 100 to 106 degrees, another warm and uncomfortable night Thursday night will only exacerbate the problem.  Haze is common in these hot airmasses, but Thursday’s haze has an extra boost from western U.S. wildfire smoke blowing through our skies over the course of the day.  In soupy air like this, we often see thunderstorms, but many communities remained storm-free Wednesday and many more will again Thursday – with some exceptions.  Cooler air aloft will allow for some storms to develop in Western New England Thursday afternoon, first in the mountains, then expanding further east during the evening.  Right now, it doesn’t look like a widespread thunderstorm day for Central and Eastern New England, but it’s likely some storms will develop through the White Mountains and Lakes region, interior Maine…and an isolated late day shower or storm can’t be ruled out in the Worcester Hills though it much less likely.  Elsewhere, as these storms weaken and drift east overnight Thursday night, some passing showers are possible.  Friday brings a similar day, though the increasing favorability for late day and evening storms nudges east, putting more of New England into that potential while high temperatures soar into the middle 90s again and dew points hold in the 70s, delivering another day of heat index values around 100°.  A cold front moves through New England from northwest to southeast Saturday, prompting scattered showers and thunder but slowly delivering cooler and less humid air to Northern New England, arriving to Southern New England by Saturday night and leaving an incredible Sunday of sunshine with pleasant, comfortable air.  Remarkably, it looks like the new, pleasant weather will persist in New England through most of next week in our exclusive First Alert 10-day forecast, though a chance of showers remains in the forecast late next week depending upon the eventual track of remnant moisture from what is currently Tropical Depression Fred over the Caribbean – our team will keep you posted.


Heat Index To Reach 105° in New England, Danger to Those Without Cooling

LKS_BOARD_PIC_WITH_TEXTA First Alert continues through Friday from our NBC10 Boston, NECN and Telemundo New England weather team for intense heat and humidity.  Wednesday’s heat index or “feels like” forecast is expected to reach 95 to 100 degrees during the afternoon, with Thursday and Friday topping out at a 100 to 105 degree heat index – the hottest feeling this season.  Heat index is something our weather team fields questions about from time to time: is it real?  What does it mean?  The heat index is a complex mathematical formula that takes both the temperature and amount of moisture in the air into account.  The basis for heat index and the impact of humidity on the body comes from the understanding that our bodies cool by the evaporation of sweat from our skin – if it’s more humid, sweat evaporates slower, meaning our bodies can’t cool as effectively.  This reduced ability for the body to cool means the impact on the body is as if the temperature were even hotter under normal humidity.  So…with the thermometer topping out around 90 Wednesday and in the middle 90s Thursday and Friday, it’s the oppressive humidity with dew point temperatures in the 70s that generates the highest impact on the body so far this summer in this stretch.  Furthermore, multiple studies have shown when the heat index fails to drop below 80° overnight, those without air conditioning don’t have a chance for the body to effectively rest and recuperate, increasing the stress from heat in the following day(s), creating the dangerous aspect of these hot stretches.  Of course, lots of heat and humidity in New England also can lead to strong thunderstorms if there’s a strong enough “trigger” to touch off the storms – that appears to be the case Wednesday, Friday and Saturday, all with a chance of thunder in the afternoon to evening from west to east, respectively.  Thursday actually may have fewer storms in New England – the most likely ones in the mountains – as any warm/cool clash in the sky is mitigated by, frankly, purely hot air, decreasing the clash needed for storm development.  A cold front passes through New England from northwest to southeast, producing a number of showers and thunderstorms but slow enough that temperatures will still reach 90 degrees in much of Southern New England, extending the heat wave to a fourth day before a dramatically different air arrives from Sunday through next week, dropping daytime high temperatures to around 80 with coastal sea breezes and vastly reduced humidity.  Toward the end of next week, it’s possible we see some showers or rain from whatever will be left of the newly formed Tropical Storm Fred, located south of Puerto Rico as of Wednesday morning, but it’s early to say and quite possible our dome of cooler, fair weather next week may hold that moisture at bay.


Dangerous Heat Index Values En Route to New England

LKS_FCST_FEELSLIKE_HOUR_BY_HOUR_NEWENGNew England is on the precipice of returning intense heat and humidity Wednesday through Friday.  Tuesday dawned with tropical showers – tropical in nature given the abundance of warm and humid air, evident by the many, small, soaking raindrops that left Eastern MA and Southern NH residents reaching for the umbrella headed out the door, but our First Alert Weather Team is predicting breaks of afternoon sunshine to bump temperatures to 80 degrees with noticeable humidity, but not yet oppressive.  Although an afternoon isolated shower is possible late Tuesday, not many communities will see one, though the onset of increasing heat and humidity Tuesday night into early Wednesday morning will deliver a few showers and even some thunder to Northern New England.  Wednesday, Thursday and Friday bring intense heat – high temperatures in the 90s – and oppressive humidity with dew points in the 70s, combining with the heat to produce heat index values of 95-100 degrees Wednesday and either side of 100 Thursday and Friday.  The typical hot summer weather advice of hydration, lightweight & light colored clothing and limiting exertion during midday hours come back into view, along with providing opportunities for cooling to those who don’t have air conditioning, particularly in urban centers of Southern New England.  Some afternoon showers and thunder are possible each afternoon in the heat and humidity, and wildfire smoke may drift through our New England sky over the second half of the week as the steering winds aloft shift.  A cold front enters New England Saturday and will break down the heat and humidity over the course of the day, sparking several showers and thunderstorms as it marches across the six-state region, likely to deliver mild and less humid air Sunday into next week, with the second half of our exclusive First Alert 10-day forecast looking pleasant and fair right now.