❰ Current Conditions

Tropical Storm Warning + 1 More Alert
Tropical Storm Warning
TROPICAL STORM WARNING REMAINS IN EFFECT

Tropical Storm Warning issued August 4 at 5:01AM EDT by NWS Boston/Norton MA

* LOCATIONS AFFECTED - Cambridge

* WIND - LATEST LOCAL FORECAST: Below tropical storm force wind - Peak Wind Forecast: 20-30 mph with gusts to 50 mph

- THREAT TO LIFE AND PROPERTY THAT INCLUDES TYPICAL FORECAST UNCERTAINTY IN TRACK, SIZE AND INTENSITY: Potential for wind 39 to 57 mph - The wind threat has remained nearly steady from the previous assessment. - PLAN: Plan for hazardous wind of equivalent tropical storm force. - PREPARE: Remaining efforts to protect property should be completed as soon as possible. Prepare for limited wind damage. - ACT: Move to safe shelter before the wind becomes hazardous.

- POTENTIAL IMPACTS: Limited - Damage to porches, awnings, carports, sheds, and unanchored mobile homes. Unsecured lightweight objects blown about. - Many large tree limbs broken off. A few trees snapped or uprooted, but with greater numbers in places where trees are shallow rooted. Some fences and roadway signs blown over. - A few roads impassable from debris, particularly within urban or heavily wooded places. Hazardous driving conditions on bridges and other elevated roadways. - Scattered power and communications outages.

* FLOODING RAIN - LATEST LOCAL FORECAST: - Peak Rainfall Amounts: No significant rainfall forecast

- THREAT TO LIFE AND PROPERTY THAT INCLUDES TYPICAL FORECAST UNCERTAINTY IN TRACK, SIZE AND INTENSITY: Little or no potential for flooding rain - The flooding rain threat has decreased from the previous assessment. - PLAN: There is little or no potential for flooding rain. - PREPARE: Little to no preparations are needed to protect against flooding rain at this time. - ACT: Monitor for changes to the forecast.

- POTENTIAL IMPACTS: Little to None - Little to no potential impacts from flooding rain.

* TORNADO - LATEST LOCAL FORECAST: - Situation is unfavorable for tornadoes

- THREAT TO LIFE AND PROPERTY THAT INCLUDES TYPICAL FORECAST UNCERTAINTY IN TRACK, SIZE AND INTENSITY: Tornadoes not expected - The tornado threat has decreased from the previous assessment. - PLAN: Tornadoes are not expected. Showers and thunderstorms with gusty winds may still occur. - PREPARE: Little to no preparations needed to protect against tornadoes at this time. Keep informed of the latest tornado situation. - ACT: Listen for changes in the forecast.

- POTENTIAL IMPACTS: Little to None - Little to no potential impacts from tornadoes.

* FOR MORE INFORMATION: - https://www.weather.gov/box
Tropical Cyclone Statement
Tropical Cyclone Statement issued August 4 at 5:12AM EDT by NWS Boston/Norton MA

This product covers Southern New England

** Tropical Storm Isaias To Impact Southern New England Later Today and Early Tonight **

Tuesday...

NEW INFORMATION ---------------

* CHANGES TO WATCHES AND WARNINGS: - None

* CURRENT WATCHES AND WARNINGS: - A Tropical Storm Warning is in effect for northern Connecticut, Massachusetts, and Rhode island.

* STORM INFORMATION: - About 530 miles southwest of Nantucket MA - 36.3N 77.5W - Storm Intensity 70 mph - Movement North-northeast or 20 degrees at 28 mph

SITUATION OVERVIEW ------------------

Tropical Storm Isaias is expected to quickly track through southeast New York and western New England this evening, before heading into northern New England. Most of the storm's impacts will occur during about a 6 hour period from late this afternoon through early tonight.

Strong southerly winds gusting to 40 to 60 mph may be capable of downing some trees and power lines. There is also the possibility of an isolated tornado, especially near the Connecticut River Valley. Rainfall totals of 1 to 3 inches are expected, with the higher totals closer to the Berkshires, where urban or small stream flooding may occur. Rainfall totals will decrease farther east. Much of Rhode Island and eastern Massachusetts should receive less than one inch of rain.

Minor coastal flooding will affect south coastal Rhode Island and Massachusetts during high tide early tonight, resulting in inundation of 1 to 2 feet ground level, primarily affecting more vulnerable shore roads and low lying areas.

Rough surf and an increased risk of dangerous rip currents will affect south coastal beaches today and Wednesday.

POTENTIAL IMPACTS -----------------

* WIND: Protect against dangerous wind having possible significant impacts across southern New England. Potential impacts in this area include: - Several large trees snapped or uprooted. - Scattered power and communications outages.

* FLOODING RAIN: Protect against rainfall flooding having possible significant impacts across parts of western Massachusetts and northern Connecticut. Potential impacts include:

- Small streams, creeks, and ditches may overflow. - Rapid inundation of underpasses, low-lying spots, and poor drainage areas. Some streets and parking lots take on moving water as storm drains and retention ponds overflow. Driving conditions become hazardous.

Elsewhere across Southern New England, little to no impact is anticipated.

* TORNADOES: Protect against a tornado event having possible limited impacts across Southern New England, especially near the Connecticut River Valley. Potential impacts include: - A few places may experience tornado damage, along with power and communications disruptions. - Large tree tops and branches snapped off, shallow-rooted trees knocked over, and minor damage to roofs.

* SURGE: Minor impacts are anticipated across south coastal Rhode Island and Massachusetts, including the Narragansett Bay shoreline, around the time of high tide tonight which occurs between 930 PM and 10 PM. Inundation of 1 to 2 feet above ground level is possible.

*PRECAUTIONARY/PREPAREDNESS ACTIONS...* EVACUATIONS: Listen to local official for recommended preparedness actions, including possible evacuation. If ordered to evacuate, do so immediately.

* OTHER PREPAREDNESS INFORMATION: Now is the time to complete all preparations to protect life and property in accordance with your emergency plan. Ensure you are in a safe location before the onset of strong winds or possible flooding.

Keep cell phones well charged. Cell phone chargers for automobiles can be helpful, but be aware of your risk for deadly carbon monoxide poisoning if your car is left idling in a garage or other poorly ventilated area.

Rapidly rising flood waters are deadly. If you are in a flood-prone area, consider moving to higher ground. Never drive through a flooded roadway. Remember, turn around don't drown!

If a Tornado Warning is issued for your area, be ready to shelter quickly, preferably away from windows and in an interior room not prone to flooding. If driving, scan the roadside for quick shelter options.

Closely monitor weather.gov, NOAA Weather radio or local news outlets for official storm information. Be ready to adapt to possible changes to the forecast. Ensure you have multiple ways to receive weather warnings.

* ADDITIONAL SOURCES OF INFORMATION: - For information on appropriate preparations see ready.gov - For information on creating an emergency plan see getagameplan.org - For additional disaster preparedness information see redcross.org
NWS Area Forecast Discussion

Area Forecast Discussion
National Weather Service Boston/Norton MA
638 AM EDT Tue Aug 4 2020

.SYNOPSIS...
Showers/thunder associated with Isaias will move up the coast
into CT and Western MA, possibly extending into RI and Eastern
MA during the day. The center of Isaias will move along the
western MA border, then continue northeast into Canada. Strong 
locally damaging winds and local downpours are expected during
this passage. Minor coastal flooding along the south-facing 
coasts are also possible. The weather improves tonight and
Wednesday, although a few lingering showers are possible. Quiet
and seasonable weather with low humidity levels to round out 
the week. Summerlike heat with oppressive humidity then return 
for early next week, with limited thunder chances.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

No changes to the forecast.

Isaias was over southeast Virginia this morning, moving on a 
NNE track. Expect it to move along coastal portions of the Mid 
Atlantic states this morning, reaching the NY border with Srn 
New England during the late afternoon and evening. Expect the 
most significant weather as the storm center passes along the 
border.

Heavy rain/flooding... PW values increase from 1.5 inches to 2.0 
inches during the day, with highest values in the afternoon/evening. 
At this same time the system will become supported by the exit 
region of the upper jet, further supporting lift in an unstable 
airmass. Expect showers and a few thunderstorms during this time 
with local downpours. The best chance of downpours will be in the CT 
Valley and Berkshire East Slope regions, with diminishing rain 
amounts toward the east. 

Strong winds... Winds aloft at 925 mb and 950 mb show 65 to 70 kt, 
available to be brought to the surface partly or fully in any heavy 
rain. These winds, or a significant fraction of them, would be 
enough to cause damage at the surface to trees/branches. Best chance 
will be in areas close to the storm center with diminishing 
likelihood farther east.

Tornadic wind... Strong 0-3Km helicity values of 400-600 move into 
Wrn MA/CT...generally the area west of Worcester...18Z/2 PM to 01Z/9 
PM. The system does have a history of generating tornadic 
circulations in storm rain bands as it moved into North
Carolina. Isolated tornadoes will be possible, mainly this 
afternoon and evening.

Daytime clouds will limit heating, but low level temps are 
supportive of max sfc temps around 80 in the west and 80-85 in the 
coastal plain. Humidity will be oppressive with dew points 70 to 75.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Tonight...

Isaias will move quickly through Northern New England and the St 
Lawrence Valley. Expect the showers to diminish early tonight with 
clearing skies after midnight. The airmass will be humid, but not as 
extreme as during the day. Dew points will lower to the 60s most 
places. With these values in place, min temps should range from 
the mid 60s to lower 70s.

Wednesday...

Upper trough remains to our west over the Great Lakes. A small jet 
moves through NY and Nrn New England, with Srn New England in the 
right entrance region. LI values are mostly sub-zero, indicating 
lingering instability. Moisture cross sections show a moist layer 
between 750-mb and 850-mb, with mixing reaching 800-mb. This 
suggests scattered showers/thunder but limited in extent. 
Temperatures at 800-mb are forecast at 12C, equiv to 17C at 850-mb 
and supportive of max sfc temps around 90, but cooler in the 
hills and at the coast.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Highlights... 

* Seasonable temps (cool nighttime lows) with low humidity levels 
  Wed nite into Fri. 

* Period of showers mainly South Coast, Cape Cod and Islands Fri 
  nite/Sat, perhaps to I-95 and into parts of northern RI/CT. 
  Otherwise, turning warmer with dry weather rest of the weekend.

* Summerlike heat and oppressive humidity levels return early next 
  week, with t-storm chances limited to the terrain Mon-Tues. 

Details... 

Wednesday Night Through Friday: 

Shaping up to be a real nice stretch of weather overall for Southern 
New England, as high pressure post-Isaias settles into the area. Dry 
continental trajectories will bring about some really comfortable 
dewpoints in the 50s. However to the south, a stationary SW/NE 
boundary (separating the much lower theta-e airmass over the land to 
the higher-dewpoint/higher theta-e air over the offshore waters) 
will lie somewhere either over or just southeast of our southern 
coastal waters, with active showers/possible thunder likely along 
its extent. The position of this feature varies across the suite of 
NWP, ranging from the well-offshore Canadian GEM to the furthest 
NW/closer-to-inland ECWMF. 

Will be opting for dryness for much of the land areas, but will 
gradually show a northwestward creep to the frontal boundary with 
related progressively higher PoP chances over our southern waters 
and potentially to the Cape and Islands toward the latter part of 
this period (late-Thurs/Fri). This northwestward shift in the 
boundary due to an approaching shortwave disturbance aloft from the 
Great Lakes that should allow for flow to turn to more onshore/SEly. 

All told, again looking at mostly sunny conditions during the day 
for most, with good diurnal ranges due to good radiational cooling. 

Friday Night into Saturday: 

Mid-level shortwave aloft interacts with the aforementioned 
lingering boundary to spread the best chances for rains across a 
somewhat larger part of Southern New England. However still a fair 
amount of uncertainty in terms of how far northwest will measurable 
precip extend. Most guidance indicates best chance for rains (up to 
40%) is Friday night along the South Coast, Cape Cod and the Islands 
(and adjacent waters). However showers may extend as far northwest 
as Tolland and Windham Counties in CT northeastward to the I-95 
corridor but this isn't certain and parts of or all these additional 
locales may end up dry.

Rest of the Weekend: 

Weak shortwave ridging aloft then resumes across Southern New 
England for the remainder of the weekend. As temperatures warm back 
closer to summerlike levels again under 850 mb temps in the mid 
teens Celsius, shallow instability which develops will be tempered 
by related subsidence owing to the height rises/shortwave ridging 
aloft. Humidity levels will be rising through the weekend and may 
start to feel more humid by Sunday. 

Early Next Week: 

A return to summerlike warmth and humidity levels rising to more 
uncomfortable/oppressive levels (mid 60s to low 70s) will be the 
main storyline Monday and Tuesday. 850 mb temps rise into the upper 
teens, bringing highs back into the mid/upper 80s to low 90s. 
Heat indices may again approach Heat Advisory levels. 

May not be much to break the heat/humidity in terms of thunder 
chances (limited to isolated coverage around the terrain in western 
MA/western CT), though models vary on timing vort energy that could 
offer more convective coverage than isolated. Still enough time and 
subsequent model cycles to iron out those timing details.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...

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

Today...Moderate confidence

VFR this morning, but trending lower through the day as showers
and scattered thunder move north with Isaias. Expect a period 
of MVFR cigs later afternoon in the heavier showers, and 
possible IFR visibilities. The best chance of this will be in CT
and Western MA. 

Isaias will pass along the western MA border 21Z-24Z/5PM-8PM.
Expect strongest winds at that time, and again favoring Western
MA and CT. 

Tonight...Moderate-high confidence

Isaias moves off through Nrn New England, eventually reaching
Canada. Cigs/Vsbys in Srn New England will improve to VFR with
clearing skies. 

Wednesday...Moderate-high confidence

Generally VFR with rain-free weather. Scattered or widely
scattered showers possible in the afternoon.

KBOS Terminal...Moderate confidence in TAF. 

KBDL Terminal...Moderate confidence in TAF. 

Outlook /Wednesday Night through Saturday/...

Wednesday Night through Friday: VFR. 

Friday Night through Saturday: VFR. Slight chance SHRA.

&&

.MARINE...
Tropical Storm Warnings continue for all coastal waters. Isaias
moves up the Eastern Seaboard, crossing Northern New England
tonight. 

Winds become southeast today, turning from the south tonight. 
Southwest winds expected Wednesday. Seas build to 10-12 feet on
the southern waters today and on the eastern waters tonight.
Seas subside to 5-6 feet on Wednesday. 

Outlook /Wednesday Night through Saturday/...

Wednesday Night: Winds less than 25 kt. Seas up to 5 ft. Slight
chance of rain showers. 

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

Thursday Night through Friday: Winds less than 25 kt. Slight
chance of rain showers. 

Friday Night through Saturday: Winds less than 25 kt. Chance of
rain showers.

&&

.HYDROLOGY...
Based upon forecast track of Isaias, heaviest rainfall is expected 
to remain to west of our area, but locations near Berkshires and 
possibly in Hartford County will see most rainfall, on order of 1-2 
inches on average with potential for as much as 3-4 inches locally 
due to S/SE upslope flow. Will maintain Flash Flood Watch for these 
locations with main threats being small stream flooding and 
significant urban/poor drainage flooding in a short time. Antecedent 
conditions are quite dry with portions of the region in drought, 
which should hinder more serious flooding (including on larger 
rivers).

Farther east, expect rainfall totals to drop off dramatically, with 
less than 1 inch across RI and eastern MA, probably less than 0.25 
inch on Cape Cod and Islands, since these areas are on eastern side 
of storm track and are farther removed from better dynamics.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Tropical Storm Warning for CTZ002>004. 
     Flash Flood Watch from noon EDT today through Wednesday 
     morning for CTZ002.
MA...Tropical Storm Warning for MAZ002>024-026. 
     Flash Flood Watch from noon EDT today through Wednesday 
     morning for MAZ002-003-008>011.
     Coastal Flood Advisory from 7 PM to 11 PM EDT this evening for 
     MAZ020-021.
RI...Tropical Storm Warning for RIZ001>008. 
     Coastal Flood Advisory from 7 PM to 11 PM EDT this evening for 
     RIZ002-004>007.
MARINE...Tropical Storm Warning for ANZ230>237-250-251-254>256. 
&&