Steamy beginning to autumn; thunderstorm chance for some

It’ll be downright steamy across most of Minnesota as astronomical autumn begins this Friday afternoon.

The autumnal equinox is at 3:02 p.m. CDT today.

Meteorological autumn began on Sept. 1:

Temperature trends

Friday afternoon highs could reach the lower 90s in about the southern half of Minnesota. The northern half of Minnesota will see mostly 70s and 80s.

Dew point temperatures Friday afternoon will be in the lower 70s over much of southern and central Minnesota.

The combination of heat and humidity has prompted a heat advisory for the Twin Cities metro area from 1 p.m. to 7 p.m. this Friday:

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Late morning update:

The National Weather Service has expanded the heat advisory to cover most of central and southern Minnesota and parts of western Wisconsin Friday afternoon and early Friday evening:

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On Saturday, high temps will range from the 60s in northwestern Minnesota to the upper 80s in the southeast:

Similar highs are expected on Sunday:

Looking ahead, Twin Cities high temps are expected to be around 75 Monday, 70 Tuesday, then in the mid 60s Wednesday and Thursday of next week.

Rain chances

The scattered morning showers and thunderstorms in the northwestern part of the metro area will move on by late morning.

Northeastern Minnesota and northwestern Wisconsin could see some scattered showers and thunderstorms into Friday afternoon.

Some scattered showers and thunderstorms could redevelop Friday afternoon and evening, especially over about the northwestern half of Minnesota, and continue into the overnight hours.

With a nearly-stationary front draped across Minnesota this weekend, the best chance of showers and thunderstorms is expected to be over the northwestern half of Minnesota.

Scattered showers and thunderstorms are also possible this weekend in the southeastern half of Minnesota, especially from Saturday evening into Sunday and Sunday evening.

The National Oceanic and Atmospheric Administration’s Global Forecast System model shows the potential rain pattern this weekend:

NOAA GFS model rainfall rate Saturday through Sunday evening, via tropicaltidbits

The color chart to the right of the loop refers to the rainfall rate (mm per hour), not to the total amount of rain.

Severe weather outlook

The Storm Prediction Center of the National Weather Service shows a slight risk of severe weather Friday and Friday night for north-central and northwestern Minnesota, with a marginal risk of severe weather over the remainder of northern Minnesota and west-central into southwestern Minnesota:

NWS Storm Prediction Center

Slight risk means that scattered severe thunderstorms are possible, marginal risk means that isolated severe thunderstorms are possible.

On Saturday, the SPC shows a marginal risk of severe weather from southwestern into northeastern Minnesota:

NWS Storm Prediction Center

Updated weather information can be heard on the Minnesota Public Radio Network, and you can also read about any watches and warnings in the MPR news live weather blog.

Fall colors

The latest fall color report from the Minnesota Department of Natural Resources shows some good fall color in parts of northern Minnesota:

Minnesota Department of Natural Resources

Hurricane Maria

Infrared to visible loop of Maria Friday morning. National Oceanic and Atmospheric Administration

The Friday morning update from the National Hurricane Center showed that Maria had max winds of 125 mph.

Maria was 30 miles north-northeast of Grand Turk Island, and was moving to the northwest.

A Hurricane Warning is in effect for the Dominican Republic from Cabo Engano to Puerto Plata, and for the Turks and Caicos Islands and the Southeastern Bahamas.

Here’s the NHC projected path of Maria:

National Hurricane Center

The complete Friday morning update from the National Hurricane Center:

Hurricane Maria Intermediate Advisory Number 25A
NWS National Hurricane Center Miami FL AL152017
800 AM EDT Fri Sep 22 2017

…HURRICANE CONDITIONS OCCURRING ON THE TURKS AND CAICOS ISLANDS…

 

SUMMARY OF 800 AM EDT…1200 UTC…INFORMATION
———————————————-
LOCATION…21.9N 70.9W
ABOUT 30 MI…50 KM NNE OF GRAND TURK ISLAND
ABOUT 465 MI…745 KM ESE OF NASSAU
MAXIMUM SUSTAINED WINDS…125 MPH…205 KM/H
PRESENT MOVEMENT…NW OR 315 DEGREES AT 7 MPH…11 KM/H
MINIMUM CENTRAL PRESSURE…959 MB…28.32 INCHES

 

WATCHES AND WARNINGS
——————–
CHANGES WITH THIS ADVISORY:

The government of the Bahamas has changed the Tropical Storm Watch
for the central Bahamas to a Tropical Storm Warning.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Hurricane Warning is in effect for…
* Dominican Republic from Cabo Engano to Puerto Plata
* Turks and Caicos Islands and the Southeastern Bahamas

A Tropical Storm Warning is in effect for…
* Dominican Republic west of Puerto Plata to the northern border of
the Dominican Republic and Haiti
* Central Bahamas

A Hurricane Warning means that hurricane conditions are expected
somewhere within the warning area. Preparations to protect life and
property should be rushed to completion.

A Tropical Storm Warning means that tropical storm conditions are
expected somewhere within the warning area.

Interests elsewhere in the Bahamas should monitor the progress of
Maria.

For storm information specific to your area, please monitor products
issued by your national meteorological service.

 

DISCUSSION AND 48-HOUR OUTLOOK
——————————
At 800 AM EDT (1200 UTC), the center of Hurricane Maria was located
near latitude 21.9 North, longitude 70.9 West. Maria is moving
toward the northwest near 7 mph (11 km/h), and a motion toward the
north-northwest is expected later today and Saturday. On the
forecast track, Maria’s eye will move near or just east of the Turks
and Caicos Islands and southeastern Bahamas today.

Maximum sustained winds are near 125 mph (205 km/h) with higher
gusts. Maria is a category 3 hurricane on the Saffir-Simpson
Hurricane Wind Scale. A gradual weakening is forecast during the
next 48 hours.

Hurricane-force winds extend outward up to 70 miles (110 km) from
the center, and tropical-storm-force winds extend outward up to 160
miles (260 km).

The minimum central pressure based on data from an Air Force
Reserve Hurricane Hunter aircraft is 959 mb (28.32 inches).

 

HAZARDS AFFECTING LAND
———————-
WIND: Tropical storm conditions across portions of the Dominican
Republic should subside during the next several hours. Hurricane
conditions are spreading into the Turks and Caicos Islands and the
southeastern Bahamas and will continue through today. Tropical
storm conditions are expected in the central Bahamas beginning
tonight.

STORM SURGE: A dangerous storm surge accompanied by large and
destructive waves will raise water levels by as much as 9 to 12 feet
above normal tide levels within the hurricane warning area of the
southeastern Bahamas and the Turks and Caicos Islands.

RAINFALL: Maria is expected to produce the following rainfall
accumulations through Saturday:

Turks and Caicos…8 to 16 inches, isolated 20 inches
Puerto Rico…additional 3 to 6 inches, isolated maximum storm
total amounts 40 inches
Eastern Dominican Republic…additional 4 to 8 inches, isolated
storm total amounts 20 inches
Western Dominican Republic and northern Haiti…additional 3 to 6
inches
Mayaguana, southeast Bahamas…4 to 8 inches
Inagua Islands and Crooked Island, Bahamas…2 to 6 inches
Rest of eastern Bahamas…1 to 3 inches

Rainfall on these islands will continue to cause life-threatening
flash floods and mudslides.

SURF: Swells generated by Maria are affecting Puerto Rico, the
Virgin Islands, the northern coast of Hispaniola, the Turks and
Caicos Islands, and the southeastern Bahamas. These swells will
reach the remainder of the Bahamas soon and should reach portions
of the United States southeastern coast today. These swells are
likely to cause life-threatening surf and rip current conditions.
Please consult products from your local weather office.

 

NEXT ADVISORY
————-
Next complete advisory at 1100 AM EDT.

The remnants of former Tropical Storm Jose are causing the continuation of tropical storm warnings for parts of New England:

Post-Tropical Cyclone Jose Intermediate Advisory Number 68A
NWS National Hurricane Center Miami FL AL122017
800 AM AST Fri Sep 22 2017

…JOSE CONTINUES TO BRING TROPICAL STORM CONDITIONS TO SOUTHERN
NEW ENGLAND…

 

SUMMARY OF 800 AM AST…1200 UTC…INFORMATION
———————————————-
LOCATION…39.7N 69.0W
ABOUT 115 MI…185 KM SSE OF NANTUCKET MASSACHUSETTS
MAXIMUM SUSTAINED WINDS…50 MPH…85 KM/H
PRESENT MOVEMENT…W OR 270 DEGREES AT 2 MPH…4 KM/H
MINIMUM CENTRAL PRESSURE…993 MB…29.32 INCHES

 

WATCHES AND WARNINGS
——————–
CHANGES WITH THIS ADVISORY:

None.

SUMMARY OF WATCHES AND WARNINGS IN EFFECT:

A Tropical Storm Warning is in effect for…
* Woods Hole to Sagamore Beach, including Cape Cod
* Block Island
* Martha’s Vineyard
* Nantucket

For storm information specific to your area, including possible
inland watches and warnings, please monitor products issued by your
local National Weather Service forecast office.

 

DISCUSSION AND 48-HOUR OUTLOOK
——————————
At 800 AM AST (1200 UTC), the center of Post-Tropical Cyclone Jose
was located near latitude 39.7 North, longitude 69.0 West. The
post-tropical cyclone is moving slowly toward the west near 2 mph (4
km/h). Jose is expected to meander well off the coast of New
England for the next several days.

Maximum sustained winds are near 50 mph (85 km/h) with higher gusts.
Gradual weakening is forecast for the next 48 hours.

Jose is a large system. Tropical-storm-force winds extend outward
up to 220 miles (350 km) from the center. A sustained wind of 39
mph (63 km/h) with a gust to 49 mph (80 km/h) was recently reported
at an unofficial site on Martha’s Vineyard.

The estimated minimum central pressure is 993 mb (29.32 inches).

 

HAZARDS AFFECTING LAND
———————-
WIND: Tropical storm conditions are expected to continue in the
warning area this morning.

SURF: Swells generated by Jose are affecting Bermuda and much of
the U.S. east coast and will likely cause dangerous surf and rip
current conditions during the next couple of days. For more
information, please consult products from your local weather office.

Rainfall: Jose is expected to produce additional rainfall
accumulations of up to one inch across Cape Cod and the offshore
Islands of Martha’s Vineyard and Nantucket through early Saturday.
When including rain that has already fallen, storm total
accumulations could reach 6 inches on Nantucket.

 

NEXT ADVISORY
————-
Next complete advisory at 1100 AM AST.

Programming note

You can hear my live weather updates on Minnesota Public Radio at 7:49 a.m. Thursdays and Fridays, and at 7:35 a.m., 9:35 a.m. and 4:35 p.m. each Saturday and Sunday.