Severe thunderstorm warning issued for Washtenaw County

NWS Detroit has issued a severe thunderstorm warning for most of Washtenaw County until 5:45pm. This warning is in the path of a storm which developed south of Jackson and is tracking northeast at 28 mph. Hazards from this storm include 60mph wind gusts and quarter-sized hail.

The storm is expected to be near Barton Hills/Ann Arbor at 5:20pm.

I will monitor this storm; as we saw earlier, storms today have been dissipating more quickly owing to the relatively cool temperatures, so this storm may no longer be severe by the times it reaches us.

KDTX Composite Reflectivity 4:26pm July 27 2013
KDTX Composite Reflectivity 4:26pm July 27 2013
WUUS53 KDTX 272026
SVRDTX
MIC161-272145-
/O.NEW.KDTX.SV.W.0092.130727T2026Z-130727T2145Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
426 PM EDT SAT JUL 27 2013

THE NATIONAL WEATHER SERVICE IN DETROIT/PONTIAC HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  WASHTENAW COUNTY IN SOUTHEAST MICHIGAN...

* UNTIL 545 PM EDT

* AT 421 PM EDT...A SEVERE THUNDERSTORM WAS LOCATED NEAR GRASS
  LAKE...AND MOVING EAST AT 25 MPH.

  HAZARD...QUARTER SIZE HAIL AND 60 MPH WIND GUSTS.

  SOURCE...RADAR INDICATED.

  IMPACT...HAIL DAMAGE TO VEHICLES IS EXPECTED. EXPECT WIND DAMAGE TO
           ROOFS...SIDING AND TREES.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
  MANCHESTER AROUND 440 PM EDT.
  PLEASANT LAKE AND CHELSEA AROUND 450 PM EDT.
  DEXTER AND HUDSON MILLS METROPARK AROUND 505 PM EDT.
  DELHI MILLS AROUND 515 PM EDT.
  BARTON HILLS AND ANN ARBOR AROUND 520 PM EDT.
  DIXBORO AND YPSILANTI AROUND 530 PM EDT.

THE WARNING INCLUDES AREAS SURROUNDING THESE LOCATIONS...
  DIXBORO...            YPSILANTI...          SALEM...
  MANCHESTER...         DEXTER...             CHELSEA...
  ANN ARBOR...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

FOR YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
BUILDING.

&&

LAT...LON 4243 8396 4243 8355 4225 8355 4207 8413
      4231 8414
TIME...MOT...LOC 2026Z 249DEG 22KT 4219 8417

HAIL...1.00IN
WIND...60MPH

$$

Severe thunderstorm approaching Ann Arbor

KDTX Vertically Integrated Liquid 4:13pm July 27, 2013
KDTX Vertically Integrated Liquid 4:13pm July 27, 2013

A severe thunderstorm has developed south of Jackson and will hit Ann Arbor around 5:00-5:10pm. The storm is currently producing 40+mph wind gusts and 1/2″ hail. It is south of Grass Lake, over Napoleon, right now.

The storm is severe-warned in Jackson County until 5pm. It may or may not be classified severe by the time it hits Ann Arbor; I don’t know how much it might dissipate before then. But I do expect to see a decent thunderstorm downtown shortly after 5pm.

I will mostly be providing updates on Twitter (@ArborWX) today.

Clarifying: excessive heat warning vs. heat advisory

For those curious, these are the criteria used in SE MI for determining whether extreme heat warrants a heat advisory or an extreme heat warning:

  • Excessive Heat Watch – Issued when the Heat Index (HI) may be at least 105° within the next 2 to 3 days.
  • Heat Advisory – Issued when the HI is expected to be at least 100° for 3 hours or more. Can be issued with lower criteria with successive days heat.
  • Excessive Heat Warning – Issued when the HI is expected to be at least 105° for 3 hours or more. Can be issued with lower criteria with successive days heat.

Source: Heat Awareness Day 2012 information, which also includes some other useful heat-related information.

(Thanks to @ryanvis for pointing me to the relevant document)

Heat advisory UPGRADED to Excessive Heat Warning

NWS Detroit has issued an excessive heat warning, effective until 8pm Friday, which replaces the heat advisory that has loomed over us for most of the week. High humidity and temperatures in the mid 90s will create heat indices around 105 degrees today. The low for tonight will be in the upper 70s! Similar conditions are expected tomorrow until a cold front moves through the area in the afternoon/evening.

This is fairly serious; especially if you’re outdoors for the art fair, drink plenty of water and be vigilant for signs of heat-related health problems. Rest in shaded or air-conditioned environments, and call 911 if you or someone else is affected by heat stroke.

Heat related safety tips:

  • Drink plenty of fluids. During hot weather you will need to increase your fluid intake, regardless of your activity level. Don’t wait until you’re thirsty to drink.
  • Replace salt and minerals.  Heavy sweating removes salt and minerals from the body. These are necessary for your body and must be replaced. If you must exercise, drink two to four glasses of cool, non-alcoholic fluids each hour. A sports beverage can replace the salt and minerals you lose in sweat. However, if you are on a low-salt diet, talk with your doctor before drinking a sports beverage or taking salt tablets.
  • Schedule outdoor activities carefully. If you must be outdoors, try to limit your outdoor activity to morning and evening hours. Try to rest often in shady areas so that your body’s thermostat will have a chance to recover.
  • Pace yourself. If you are not accustomed to working or exercising in a hot environment, start slowly and pick up the pace gradually. If exertion in the heat makes your heart pound and leaves you gasping for breath, STOP all activity. Get into a cool area or at least into the shade, and rest, especially if you become lightheaded, confused, weak, or faint.
  • Use a buddy system. When working in the heat, monitor the condition of your co-workers and have someone do the same for you. Heat-induced illness can cause a person to become confused or lose consciousness.
  • Don’t leave children or pets in cars. Even in cool temperatures, cars can heat up to dangerous temperatures very quickly. Even with the windows cracked open, interior temperatures can rise almost 20 degrees Fahrenheit within the first 10 minutes. Anyone or any pet left inside is at risk for serious heat-related illnesses or even death. Children who are left unattended in parked cars are at greatest risk for heat stroke, and possibly death.

The full warning text follows, with preparedness advice:

WWUS73 KDTX 181335
NPWDTX

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
935 AM EDT THU JUL 18 2013

...DANGEROUSLY HOT AND HUMID CONDITIONS PERSISTING THROUGH
FRIDAY...

.A STRONG HIGH PRESSURE SYSTEM IS RESULTING IN AN EXTENDED
STRETCH OF HOT AND HUMID CONDITIONS. VERY HUMID CONDITIONS
COMBINED WITH TEMPERATURES RISING INTO THE MID 90S WILL RESULT IN
HEAT INDICES AROUND 105 DEGREES THIS AFTERNOON. IN ADDITION...
OVERNIGHT RELIEF FROM THE HEAT WILL BE MINIMAL AS HUMID CONDITIONS
PERSIST AND LOWS HOLD IN THE UPPER 70S. SIMILAR CONDITIONS ARE
EXPECTED TOMORROW BEFORE A COLD FRONT PROVIDES RELIEF FOR THE
WEEKEND.

MIZ047>049-053>055-060>063-068>070-075-076-082-083-190400-
/O.UPG.KDTX.HT.Y.0001.000000T0000Z-130720T0000Z/
/O.NEW.KDTX.EH.W.0001.130718T1335Z-130720T0000Z/
MIDLAND-BAY-HURON-SAGINAW-TUSCOLA-SANILAC-SHIAWASSEE-GENESEE-
LAPEER-ST. CLAIR-LIVINGSTON-OAKLAND-MACOMB-WASHTENAW-WAYNE-
LENAWEE-MONROE-
INCLUDING THE CITIES OF...MIDLAND...BAY CITY...BAD AXE...
SAGINAW...CARO...SANDUSKY...OWOSSO...FLINT...LAPEER...
PORT HURON...HOWELL...PONTIAC...WARREN...ANN ARBOR...DETROIT...
ADRIAN...MONROE
935 AM EDT THU JUL 18 2013

...EXCESSIVE HEAT WARNING IN EFFECT UNTIL 8 PM EDT FRIDAY...

THE NATIONAL WEATHER SERVICE IN DETROIT/PONTIAC HAS ISSUED AN
EXCESSIVE HEAT WARNING...WHICH IS IN EFFECT UNTIL 8 PM EDT
FRIDAY. THE HEAT ADVISORY IS NO LONGER IN EFFECT.

 * HIGH HUMIDITY AND MAX TEMPERATURES IN THE MID 90S THIS
   AFTERNOON RESULTING IN HEAT INDICES AROUND 105 DEGREES.

 * LITTLE OVERNIGHT RELIEF WITH HUMIDITY PERSISTING AND LOWS IN
   THE UPPER 70S.

 * CONTINUED HOT TOMORROW WITH HIGHS IN THE LOW TO MID 90S
   RESULTING IN HEAT INDICES OF 95 TO 105 DEGREES.

IMPACTS...

  * HEAT STROKE...HEAT EXHAUSTION AND OTHER HEAT RELATED ILLNESSES
    WILL BE POSSIBLE...ESPECIALLY IF YOU SPEND A SIGNIFICANT
    AMOUNT OF TIME OUTDOORS...OR ARE INVOLVED IN ANY STRENUOUS
    OUTDOOR ACTIVITY. THE CUMULATIVE EFFECTS OF HIGH DAYTIME HEAT
    INDICES AND WARM OVERNIGHT TEMPERATURES CAN TAKE A TOLL ON THE
    HEALTH OF PEOPLE LIVING IN AREAS WITHOUT AIR CONDITIONING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

 * TAKE EXTRA PRECAUTIONS...IF YOU WORK OR SPEND TIME OUTSIDE.
WHEN POSSIBLE...RESCHEDULE STRENUOUS ACTIVITIES TO EARLY MORNING
OR EVENING. KNOW THE SIGNS AND SYMPTOMS OF HEAT EXHAUSTION AND
HEAT STROKE. WEAR LIGHT WEIGHT AND LOOSE FITTING CLOTHING WHEN
POSSIBLE AND DRINK PLENTY OF WATER.

TO REDUCE RISK DURING OUTDOOR WORK...THE OCCUPATIONAL SAFETY AND
HEALTH ADMINISTRATION RECOMMENDS SCHEDULING FREQUENT REST BREAKS
IN SHADED OR AIR CONDITIONED ENVIRONMENTS. ANYONE OVERCOME BY
HEAT SHOULD BE MOVED TO A COOL AND SHADED LOCATION.  HEAT STROKE
IS AN EMERGENCY - CALL 911.

 * PREPARE...PLAN...AND STAY INFORMED. VISIT
   HTTP://GO.USA.GOV/RR8

&&

$$