Issued by NWS Denver/Boulder, CO
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46 47
48
49
50
000 NOUS45 KBOU 222147 PNSBOU PUBLIC INFORMATION STATEMENT NATIONAL WEATHER SERVICE BOULDER CO 400 PM WED APR 22 2009 STRONG STRAIGHT LINE WINDS AND LARGE HAIL ARE MAJOR WEATHER THREATS IN COLORADO... ACROSS THE CENTENNIAL STATE...THUNDERSTORMS CAN DEVELOP BY MIDDAY AND CARRY ON INTO THE EVENING HOURS. AS MENTIONED EARLIER DURING THIS SEVERE WEATHER AWARENESS WEEK...SOME THREATS FROM THUNDERSTORMS INCLUDE TORNADOES...FLOODING AND LIGHTNING. TORNADOES CAN BE THE FRONT PAGE HEADLINE IN NEWSPAPERS OR THE TOP STORY ON RADIO OR TELEVISION NEWS IN COLORADO...BUT DAMAGING STRAIGHT LINE WINDS OF TORNADO AND HURRICANE FORCE CAN ALSO INJURE AND KILL ANIMALS AND HUMANS. DOWNBURST WINDS FROM A THUNDERSTORM USUALLY RESULT WHEN AN AREA WITHIN THE STORM IS COOLED BY RAIN...HAIL...OR EVAPORATION...WHICH QUICKLY COOLS THE AIR. THIS POCKET OF COOLED AIR...HEAVIER THAN THE SURROUNDING AIR...ACCELERATES DOWNWARD TO THE GROUND. AS THE COOL AIR SLAMS INTO THE GROUND...IT SPREADS OUT FROM THE AREA OF IMPACT. THIS PROCESS...IN EXTREME CASES...CAN CAUSE WINDS HIGHER THAN 100 MPH. WEATHER FORECASTERS CALL THESE BURSTS OF WIND MICROBURSTS IF THEY ARE LESS THAN 2 1/2 MILES ACROSS AND MACROBURSTS IF THEY ARE GREATER THAN 2 1/2 MILES ACROSS. THESE DOWNBURSTS OF AIR CAN BE VERY HAZARDOUS AND EVEN LIFE THREATENING TO PILOTS AND CAN CAUSE EXTENSIVE DAMAGE...INJURIES AND FATALITIES AT GROUND LEVEL AS WELL. TRY TO GET INDOORS DURING ALL THUNDERSTORM ACTIVITY. HIGH WINDS CAN SUDDENLY DEVELOP...WHICH CAN CAUSE THINGS ON THE GROUND TO BECOME SWIFT MOVING AIRBORNE MISSILES...WHICH CAN INJURE OR KILL. HAIL...ANOTHER THUNDERSTORM THREAT...OFTEN OCCURS IN COLORADO. HAIL FORMS WITHIN THUNDERSTORMS AS LIQUID WATER FREEZES IN THE COLD MID AND UPPER LEVELS OF THE STORMS. THE HAILSTONES ARE KEPT ALOFT BY STRONG UPDRAFT WINDS FOR A TIME...THEN WHEN THEY BECOME TOO LARGE TO BE KEPT ALOFT BY THE UPDRAFTS...THEY CASCADE TO THE GROUND. HAILSTONES VARY FROM PEA SIZE...ABOUT 3/8 OF AN INCH IN DIAMETER...TO LARGER THAN GRAPEFRUITS...NEARLY 5 INCHES IN DIAMETER. HAILSTONES CAN DO TREMENDOUS DAMAGE TO FARM CROPS...EITHER AS LARGE HAILSTONES OR AS A CONCENTRATED FALL OF SMALL HAILSTONES THAT ACCUMULATE TO A DEPTH OF SEVERAL INCHES. LARGE HAIL CAN EASILY DAMAGE VEHICLES AND BUILDINGS...AND CAN BE LIFE THREATENING TO ANIMALS AND PEOPLE. AGAIN...TRY TO GET INDOORS DURING ALL THUNDERSTORMS. A FALL OF SMALL HAIL CAN SUDDENLY CHANGE TO A FALL OF VERY LARGE ICE MISSILES...THAT CAN INJURE OR KILL. THE NATIONAL WEATHER SERVICE ISSUES SEVERE THUNDERSTORM WARNINGS FOR WINDS OF 58 MPH OR HIGHER AND FOR LARGE HAIL ONE INCH IN DIAMETER OR LARGER. REALIZE THAT SOME STORMS ARE CAPABLE OF MUCH LARGER HAIL AND MUCH HIGHER WIND...SO WHEN YOU HEAR ABOUT A SEVERE THUNDERSTORM WARNING...SEEK SHELTER. WHEN THUNDERSTORMS...WITH ALL THEIR HAZARDS...THREATEN YOU THIS SEVERE WEATHER SEASON...TUNE TO NOAA ALL HAZARDS WEATHER RADIO. IN EACH PLACE YOU FIND YOURSELF DURING THREATENING WEATHER DAYS... PLAN OUT THE ACTIONS YOU WOULD TAKE IF WEATHER WERE TO BECOME LIFE THREATENING. THE NATIONAL WEATHER SERVICE WISHES YOU A SAFE SEVERE WEATHER SEASON.
