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

&&

$$

Scattered thunderstorms possible this afternoon/evening; mild severe potential (July 18)

Very hot, humid air over southern lower MI is likely to contribute to some scattered thunderstorm development across the area this afternoon into the night. These storms will have the potential for heavy rainfall as they move east at 20-30mph, which could cause localized flooding. There is a slight chance of some storms becoming strong or severe, but that risk is most prevalent over the thumb region of the state; most of any storms that develop are expected to carry very little hail or damaging wind risk, and virtually no tornado potential.

Also keep in mind the heat advisory in effect today until 8pm tomorrow: drink plenty of water, do not leave children or pets in cars, and stay indoors as much as possible. (Heat advisory text from NWS Detroit)

It is impossible to predict specifically whether any storms will hit Ann Arbor. As those at the Townie Street Party saw Monday night,  it’s possible for the skies around downtown to look very ominous with thunderstorms, but for us to receive only a few drops of rain, especially with storms which are nearly stationary. Storms this afternoon will be similarly very localized.

Looking forward, we can expect Friday to start out the same: hot and humid. Thunderstorms are expected Friday and Friday night as a cold front comes south into the area, bringing slightly cooler temperatures for us. Friday’s storms will be strong, with some severe potential (damaging winds and large hail will be a risk across the area), and they are expected to bring torrential rainfall. Saturday will be a bit cooler, with some risk of thunderstorms.

Here’s today’s hazardous weather outlook:

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
431 AM EDT THU JUL 18 2013

MIZ047>049-053>055-060>063-068>070-075-076-082-083-190900-
MIDLAND-BAY-HURON-SAGINAW-TUSCOLA-SANILAC-SHIAWASSEE-GENESEE-LAPEER-
ST. CLAIR-LIVINGSTON-OAKLAND-MACOMB-WASHTENAW-WAYNE-LENAWEE-MONROE-
431 AM EDT THU JUL 18 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST
MICHIGAN.

.DAY ONE...TODAY AND TONIGHT

A HEAT ADVISORY IS IN EFFECT TODAY AND TONIGHT AS HEAT INDEX
VALUES REACH OR EXCEED 100 DEGREES DURING THE DAY AND ONLY FALL
INTO THE UPPER 70S TONIGHT. PLEASE SEE THE LATEST FORECASTS AND
STATEMENTS FOR DETAILS.

SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP TODAY WITH A FEW
STORMS CONTINUING OVERNIGHT. A FEW STRONG TO SEVERE STORMS MAY DEVELOP...WITH
THE BEST POTENTIAL FOR SEVERE WEATHER OVER THE THUMB. STORMS WILL
ALSO BE CAPABLE OF VERY HEAVY RAINFALL AS THEY MOVE TO THE EAST AT
20 TO 30 MPH.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

A HEAT ADVISORY REMAINS IN EFFECT THROUGH FRIDAY. THE PROLONGED
PERIOD OF HOT DAYTIME TEMPERATURES AND WARM AND MUGGY NIGHTS WILL
INCREASE STRESS ON THE BODY.

THUNDERSTORMS ARE LIKELY FRIDAY AND FRIDAY NIGHT AS A COLD FRONT
DROPS SOUTH THROUGH THE AREA. THERE IS A CHANCE FOR SEVERE WEATHER
AND TORRENTIAL RAINFALL WITH THESE STORMS. THE THREAT FOR
THUNDERSTORMS WILL CONTINUE INTO SATURDAY...HOWEVER COVERAGE AND
INTENSITY WILL BE LESS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

$$

And, for reference, the heat advisory text:

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

...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 INDICIES 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>070-075-076-082-083-182015-
/O.CON.KDTX.HT.Y.0001.000000T0000Z-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
353 AM EDT THU JUL 18 2013

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 8 PM EDT FRIDAY...

HAZARDOUS WEATHER...

 * HIGH HUMIDITY AND MAX TEMPERATURES IN THE LOW TO MID 90S
   RESULTING IN HEAT INDICIES OF 95 TO 105 DEGREES THROUGH
   FRIDAY.

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

IMPACTS...

 * HEAT EXHAUSTION OR HEAT STROKE IS POSSIBLE IN EXTREME CASES
   WHERE NO PROTECTIVE ACTION IS TAKEN.

 * MUSCLE CRAMPS AND SUN BURNS ARE ALSO POSSIBLE

PRECAUTIONARY/PREPAREDNESS ACTIONS...

 * A HEAT ADVISORY MEANS THAT A PERIOD OF HOT TEMPERATURES IS
   EXPECTED. THE COMBINATION OF HOT TEMPERATURES AND HIGH
   HUMIDITY WILL COMBINE TO CREATE A SITUATION IN WHICH HEAT
   ILLNESSES ARE POSSIBLE. DRINK PLENTY OF FLUIDS...STAY IN AN
   AIR-CONDITIONED ROOM...STAY OUT OF THE SUN...AND CHECK ON
   RELATIVES AND NEIGHBORS. CHILDREN AND PETS SHOULD NEVER BE
   LEFT UNATTENDED IN VEHICLES UNDER ANY CIRCUMSTANCES.

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

&&

$$

Heat advisory extended through Friday 8pm

The heat and humidity is here to stay, at least until a cold front moves through the area Friday night. The NWS has extended our heat advisory to be effective until Friday 8pm.

Expect unusually hot, humid conditions until then, with heat indices above 100° and lows only in the 70s.

Remember:

  • Stay hydrated, especially if you’re outside for long periods of time; drink plenty of water, not pop, coffee, etc
  • Never leave children or pets in a car for any amount of time, for any reason
  • Wear sunscreen
  • Look out for symptoms of dehydration, heat exhaustion, and heat stroke
  • As much as possible, stay in air-conditioned buildings
  • As much as possible, avoid being in the sun
WWUS73 KDTX 171921
NPWDTX

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
321 PM EDT WED JUL 17 2013

...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 LOW TO MID 90S DURING THE
AFTERNOON HOURS WILL RESULT IN HEAT INDICIES OF 95 TO 105 DEGREES.
IN ADDITION...OVERNIGHT RELIEF FROM THE HEAT WILL BE MINIMAL AS
HUMID CONDITIONS PERSIST AND LOWS HOLD PREDOMINATELY IN THE MID
70S. A COLD FRONT MOVING THROUGH SOUTHEAST MICHIGAN FRIDAY
EVENING AND NIGHT WILL PROVIDE RELIEF FROM THE HEAT AS WE HEAD
INTO THE WEEEKEND.

MIZ047>049-053>055-060>063-068>070-075-076-082-083-180930-
/O.EXT.KDTX.HT.Y.0001.000000T0000Z-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
321 PM EDT WED JUL 17 2013

...HEAT ADVISORY NOW IN EFFECT UNTIL 8 PM EDT FRIDAY...

THE HEAT ADVISORY IS NOW IN EFFECT UNTIL 8 PM EDT FRIDAY.

HAZARDOUS WEATHER...

 * HIGH HUMIDITY AND MAX TEMPERATURES IN THE LOW TO MID 90S RESULTING
   IN HEAT INDICIES OF 95 TO 105 DEGREES THROUGH FRIDAY.

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

IMPACTS...

 * HEAT EXHAUSTION OR HEAT STROKE IS POSSIBLE IN EXTREME CASES
   WHERE NO PROTECTIVE ACTION IS TAKEN.

 * MUSCLE CRAMPS AND SUN BURNS ARE ALSO POSSIBLE

PRECAUTIONARY/PREPAREDNESS ACTIONS...

 * A HEAT ADVISORY MEANS THAT A PERIOD OF HOT TEMPERATURES IS
   EXPECTED. THE COMBINATION OF HOT TEMPERATURES AND HIGH
   HUMIDITY WILL COMBINE TO CREATE A SITUATION IN WHICH HEAT
   ILLNESSES ARE POSSIBLE. DRINK PLENTY OF FLUIDS...STAY IN AN
   AIR-CONDITIONED ROOM...STAY OUT OF THE SUN...AND CHECK ON
   RELATIVES AND NEIGHBORS. CHILDREN AND PETS SHOULD NEVER BE
   LEFT UNATTENDED IN VEHICLES UNDER ANY CIRCUMSTANCES.

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

&&

$$

SF