Moderately strong thunderstorm approaching Ann Arbor

A somewhat strong thunderstorm is expected to reach Ann Arbor around 10:30-10:35 tonight. The storm is not classified as severe; but we can expect 30+ mph wind gusts, heavy rain for ~15 minutes (light rain for much longer), some lightning, and pea-sized hail.

SPC’s outlooks put us at a 5% risk of hail or damaging wind through tomorrow morning.

KDTX Composite Reflectivity 10:13pm May 30, 2013
KDTX Composite Reflectivity 10:13pm May 30, 2013

Special Weather Statement:

WWUS83 KDTX 310211
SPSDTX

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1011 PM EDT THU MAY 30 2013

MIZ068-069-075-076-082-083-310345-
LENAWEE-LIVINGSTON-MONROE-OAKLAND-WASHTENAW-WAYNE-
1011 PM EDT THU MAY 30 2013

...SPECIAL WEATHER STATEMENT...

AT 1008 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 6 MILES NORTHEAST OF TECUMSEH...MOVING NORTHEAST
AT 35 MPH.

PEA SIZE HAIL AND WINDS GREATER THAN 30 MPH ARE POSSIBLE WITH THIS
STORM.

* THE THUNDERSTORM WILL BE NEAR...
 SALINE BY 1020 PM EDT...
 ANN ARBOR BY 1035 PM EDT...
 DIXBORO AND YPSILANTI BY 1040 PM EDT...
 SALEM BY 1055 PM EDT...
 NORTHVILLE BY 1100 PM EDT...
 NOVI BY 1105 PM EDT...
 WEST BLOOMFIELD BY 1120 PM EDT...

GUSTY WINDS MAY CAUSE SMALL OBJECTS SUCH AS TRASH BINS TO BLOW
AROUND. SEEK SHELTER IN A STURDY STRUCTURE UNTIL THIS STORM HAS
PASSED.

$$

DG

Thunderstorms expected across the area this evening; moderate severe potential

This afternoon, mid lower Michigan has seen numerous severe thunderstorms form rapidly across the state. Ann Arbor is included in the very south of an area which may receive a severe thunderstorm watch in the next couple hours.

Thunderstorm activity across southern Michigan is likely to increase over the next few hours due to  a very warm, moist, unstable atmosphere; the main threat from any storms is expected to be strong wind gusts, with isolated tornadoes possible.

Reading: SPC MD 0833

SPC Mesoscale Discussion 0833
SPC Mesoscale Discussion 0833

Update: Worth noting: the thunderstorm outlook effective 8pm-midnight puts us at a 10% risk of thunderstorms; as the night comes and temperatures cool, this threat should diminish rapidly after dark.

Thunderstorm Outlook May 20, 2013 8pm-midnight
Thunderstorm Outlook May 20, 2013 8pm-midnight

Update on thunderstorms moving through SE MI

A line of thunderstorms currently stretching from north of Howell to Dundee is expected to continue strengthening and moving northeast at 30mph.

This line may bring 30+mph winds, small hail, and occasional lightning along with heavy rain. The rain downpour lasted about 10 minutes in Ann Arbor and was quite heavy.

NWS Detroit issued the following special weather statement.

WWUS83 KDTX 301736
SPSDTX

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
136 PM EDT THU MAY 30 2013

MIZ068-069-075-076-301830-
LIVINGSTON-OAKLAND-WASHTENAW-WAYNE-
136 PM EDT THU MAY 30 2013

...SPECIAL WEATHER STATEMENT...

AT 130 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 5 MILES WEST OF ANN ARBOR...MOVING NORTHEAST AT
30 MPH.

PEA SIZE HAIL...WINDS GREATER THAN 30 MPH...OCCASIONAL CLOUD TO
GROUND LIGHTNING...BRIEF HEAVY DOWNPOURS...ARE POSSIBLE WITH THIS
STORM.

* THE THUNDERSTORM WILL BE NEAR...
 ANN ARBOR BY 140 PM EDT...
 DIXBORO BY 145 PM EDT...
 WHITMORE LAKE BY 150 PM EDT...
 SALEM AND SOUTH LYON BY 200 PM EDT...
 NORTHVILLE BY 210 PM EDT...
 NOVI BY 215 PM EDT...
 WEST BLOOMFIELD BY 230 PM EDT...

GUSTY WINDS MAY CAUSE SMALL OBJECTS SUCH AS TRASH BINS TO BLOW
AROUND. STAY AWAY FROM HIGH OBJECTS OUTDOORS SUCH AS TREES. SEEK
SHELTER IN A STURDY STRUCTURE UNTIL THIS STORM HAS PASSED.

$$

SS/MR

Increased thunderstorm risk this afternoon and evening

Looks like we have a better chance of thunderstorms today than was expected this morning. The 12:30 thunderstorm outlook puts us at a 40% chance of storms from 4-8pm, and we’re back to a 10% chance 8pm-midnight. (Outlook images below.)

Storms this afternoon and evening are still not expected to bring widespread severe weather, though isolated storms could bring damaging wind gusts and some hail. (Updated: today’s day 1 outlook effective 12:30pm through tonight puts us at a 5% risk for both hail and damaging winds along with these storms.)

There’s also a line of rapidly-developing cells headed this way shortly which should bring fairly heavy (but short-lived) rain and a little lightning (image below). These storms are not severe at this time. (Update: this line is expected to bring heavy rain for a short period of time, some lightning, and minimal risk of damaging winds or hail.)

Additionally, NWS Detroit has issued a statement regarding thunderstorm development in SW MI (extending as far east as Jackson) early this afternoon:

SCATTERED THUNDERSTORMS WILL DEVELOP ACROSS SOUTHWEST LOWER MICHIGAN
THROUGH 2 PM. THE BEST CHANCES FOR THUNDERSTORMS WILL BE EAST OF A
HOLLAND TO REED CITY LINE.

MOST STORMS WILL BE ACCOMPANIED BY BRIEF HEAVY DOWNPOURS AND GUSTY WINDS
BUT A FEW WILL BRING UP TO PENNY SIZED HAIL AND FREQUENT CLOUD-
TO-GROUND LIGHTNING.
DTX Composite Reflectivity May 20, 2013 1:13pm
DTX Composite Reflectivity May 20, 2013 1:13pm

Thunderstorm outlooks:

SPC Thunderstorm Outlook May 30, 2013 4-8pm
SPC Thunderstorm Outlook May 30, 2013 4-8pm
SPC Thunderstorm Outlook May 30, 2013 8pm-midnight
SPC Thunderstorm Outlook May 30, 2013 8pm-midnight

Additional reading: today’s hazardous weather outlook from NWS Detroit (text follows).

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
428 AM EDT THU MAY 30 2013

MIZ047>049-053>055-060>063-068>070-075-076-082-083-310830-
MIDLAND-BAY-HURON-SAGINAW-TUSCOLA-SANILAC-SHIAWASSEE-GENESEE-LAPEER-
ST. CLAIR-LIVINGSTON-OAKLAND-MACOMB-WASHTENAW-WAYNE-LENAWEE-MONROE-
428 AM EDT THU MAY 30 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST
MICHIGAN.

.DAY ONE...TODAY AND TONIGHT

THERE IS A CHANCE OF THUNDERSTORMS THIS AFTERNOON AND TONIGHT.
WIDESPREAD SEVERE WEATHER IS NOT EXPECTED. HOWEVER SOME ISOLATED
STORMS MAY PRODUCE WIND GUSTS UP TO 60 MPH. STORM MOTION WILL BE
TO THE NORTHEAST AT 30 MPH. THE CHANCE OF STORMS WILL BE THE
RESULT OF A WARM AND UNSTABLE AIRMASS OVER THE REGION.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THERE IS A CHANCE OF THUNDERSTORMS FRIDAY AND SATURDAY AS A WARM
AND HUMID AIRMASS RESIDES OVER THE REGION AND A FRONTAL BOUNDARY
APPROACHES FROM THE WEST. THERE IS A SLIGHT RISK OF SEVERE STORMS
BOTH DAYS. THE POTENTIAL FOR MULTIPLE ROUNDS OF THUNDERSTORMS MAY
ALSO LEAD TO A POTENTIAL FOR FLOODING. MULTIPLE UPPER LEVEL
DISTURBANCES TRAVERSING THE REGION WITHIN THIS UNSTABLE AIRMASS
WILL PROVIDE THE CHANCES FOR MULTIPLE ROUNDS OF THUNDERSTORMS OVER
THE NEXT COUPLE OF DAYS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED AT THIS TIME.

$$

Diminished risk of thunderstorms this evening/tonight

The SPC’s afternoon thunderstorm outlook puts us at a 10% chance of thunderstorms through 8am tomorrow. Note that this is a diminished risk from this morning’s outlook. We have a 5% chance of hail or damaging wind, but any storms which develop are not likely to be severe.

Thunderstorm Outlook May 29 2013 8pm-midnight
Thunderstorm Outlook May 29 2013 8pm-midnight
Thunderstorm Outlook May 30 2013 midnight-8am
Thunderstorm Outlook May 30 2013 midnight-8am