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NOUS46 KOTX 011039
PNSOTX

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE SPOKANE WA
400 AM PDT WED MAY 1 2013

...THE WEEK OF APRIL 28 THROUGH MAY 4 IS SEVERE WEATHER AWARENESS
WEEK IN IDAHO...OREGON...AND WASHINGTON...

...STRONG STRAIGHT-LINE WINDS...LARGE HAIL...AND LIGHTNING ARE MAJOR
WEATHER THREATS IN THE NORTHWEST...

THUNDERSTORMS MAY FORM BY MIDDAY AND CARRY ON INTO THE EVENING HOURS
OR POSSIBLY THROUGH THE NIGHT.  PRIMARY THREATS FROM THUNDERSTORMS
INCLUDE LARGE HAIL...LIGHTNING...AND STRONG GUSTY WINDS.

STRAIGHT LINE WINDS

DOWNBURST WINDS FROM A THUNDERSTORM USUALLY RESULT WHEN AN AREA OF
AIR WITHIN THE STORM IS COOLED BY RAINDROPS...OR BY THE
EVAPORATION OF THE RAINDROPS.  THIS POCKET OF COOLED AIR...HEAVIER
THAN THE SURROUNDING AIR...ACCELERATES DOWNWARD TO THE GROUND.  AS
THE COOL AIR IMPACTS THE GROUND...IT QUICKLY SPREADS OUT CAUSING THE
GUSTY WINDS.

THIS PROCESS CAN CAUSE WINDS TO EXCEED 60 MPH AND IN EXTREME CASES
NEAR 100 MPH.  WEATHER FORECASTERS CALL THESE BURSTS OF WIND
"MICROBURSTS" IF THEY ARE LESS THAN 2 1/2 MILES ACROSS AND
"MACROBURSTS" IF THEY COVER A LARGER AREA.  THESE DOWNBURSTS OF AIR
CAN BE VERY HAZARDOUS AND EVEN LIFE THREATENING TO PEOPLE FLYING IN
AIRPLANES AND CAN CAUSE EXTENSIVE DAMAGE...INJURIES AND FATALITIES
AT GROUND LEVEL AS WELL.

TRY TO GET INDOORS DURING ALL THUNDERSTORM ACTIVITY.  DOWNBURST
WINDS CAN SUDDENLY DEVELOP...CAUSING POORLY SECURED OR LIGHTWEIGHT
ITEMS ON THE GROUND TO BECOME AIRBORNE PROJECTILES.

HAIL

HAIL...ANOTHER THUNDERSTORM THREAT...OFTEN OCCURS IN THE NORTHWEST.
HAIL FORMS WITHIN THUNDERSTORMS AS LIQUID WATER FREEZES IN COLD MID
AND UPPER LEVELS OF THE STORMS.  THE ICE IS KEPT ALOFT BY STRONG
UPDRAFT WINDS FOR A TIME...THEN WHEN IT BECOMES TOO LARGE TO BE KEPT
ALOFT BY THE UPDRAFT...IT CASCADES TO THE GROUND.

HAILSTONES MAY VARY FROM PEA-SIZE TO LARGER THAN SOFTBALLS.
HAILSTONES CAN DO TREMENDOUS DAMAGE TO FARM CROPS...EITHER AS LARGE
HAILSTONES OR AS A CONCENTRATED FALL OF SMALL HAILSTONES THAT
ACCUMULATES TO A DEPTH OF SEVERAL INCHES.  LARGE HAIL CAN EASILY
DAMAGE VEHICLES AND BUILDINGS...AND CAN BE LIFE-THREATENING TO
ANIMALS AND PEOPLE.  EVEN SMALL HAIL CAN BE DANGEROUS TO MOTORISTS
WHEN IT ACCUMULATES ON ROADWAYS.

LIGHTNING

ONE ASPECT OF SPRING AND SUMMER STORMS IS LIGHTNING.  IN THE UNITED
STATES AN AVERAGE OF 55 PEOPLE ARE KILLED BY LIGHTNING EACH YEAR AND
SEVERAL HUNDRED OTHERS ARE INJURED AND ARE LEFT TO COPE WITH
PERMANENT DISABILITIES.

LIGHTNING OFTEN STRIKES AS FAR AS 10 MILES AWAY FROM ANY
RAINFALL...AND HAS BEEN DOCUMENTED TO STRIKE UP TO 70 MILES AWAY
FROM THE THUNDERSTORM WHICH GENERATED THE LIGHTNING.  MANY LIGHTNING
VICTIMS ARE STRUCK AHEAD OF THE STORM OR SHORTLY AFTER THE STORM HAS
PASSED. DO NOT WAIT FOR THE RAIN TO START BEFORE SEEKING SHELTER AND
DO NOT LEAVE THE SHELTER JUST BECAUSE THE RAIN HAS ENDED.

OUTDOORS IS THE MOST DANGEROUS PLACE TO BE DURING A THUNDERSTORM.
WATCH FOR DARKENING CLOUD BASES AND HEAD TO SAFETY BEFORE THAT FIRST
LIGHTNING FLASH.  IF YOU CAN HEAR THUNDER...THE STORM IS CLOSE
ENOUGH THAT IT COULD STRIKE YOUR LOCATION AT ANY MOMENT...AND YOU
SHOULD SEEK SHELTER.  IF LIGHTNING IS FORECAST...PLAN AN ALTERNATE
ACTIVITY OR KNOW WHERE YOU CAN TAKE COVER QUICKLY.

DON`T BE THE TALLEST OBJECT AROUND. IN THE MOUNTAINS...DO NOT REMAIN
ABOVE THE TREE LINE.  NEVER SEEK SHELTER UNDER AN ISOLATED TREE OR
A SMALL GROUP OF TREES.  IF IN A HEAVILY FORESTED AREA...SEEK
SHELTER IN A LOW SPOT AWAY FROM TALLER TREES.  IF THERE IS NO
SHELTER...SQUAT LOW TO THE GROUND...CLASP YOUR HANDS AROUND YOUR
KNEES AND PUT YOUR CHIN TO YOUR CHEST...MAKING YOURSELF THE SMALLEST
TARGET POSSIBLE WHILE MINIMIZING CONTACT WITH THE GROUND.

IF SOMEONE IS STRUCK BY LIGHTNING...CALL 9-1-1 OR YOUR LOCAL
AMBULANCE SERVICE.  GIVE FIRST AID AS QUICKLY AS POSSIBLE. PEOPLE
STRUCK BY LIGHTNING CARRY NO ELECTRICAL CHARGE THAT CAN SHOCK
OTHERS.  YOU CAN EXAMINE THEM WITHOUT RISK.

TRY TO GET INDOORS DURING ALL THUNDERSTORMS.  WHEN
THUNDERSTORMS...WITH ALL THEIR HAZARDS...THREATEN YOU THIS SEVERE
WEATHER SEASON...TUNE TO NOAA WEATHER RADIO...OR COMMERCIAL RADIO OR
TELEVISION STATIONS FOR UP TO DATE INFORMATION.

THIS WEEK IS SEVERE WEATHER AWARENESS WEEK IN THE NORTHWEST.  NOW IS
THE TIME TO GET PREPARED FOR THUNDERSTORMS AND HAZARDOUS WEATHER
SUCH AS STRONG GUSTY WINDS...HAIL...AND LIGHTNING.  PUBLIC SAFETY
INFORMATION STATEMENTS WILL BE ISSUED THROUGHOUT THE WEEK TO HELP
YOU KNOW HOW TO RESPOND WHEN SEVERE WEATHER THREATENS.

THIS MESSAGE IS BROUGHT TO YOU BY YOUR LOCAL NATIONAL WEATHER
SERVICE OFFICE IN SPOKANE, WASHINGTON.

ADDITIONAL INFORMATION CAN BE FOUND ON THE WEB AT WEATHER.GOV.

$$