Thought this was an interesting PNS (Public Information Statement) from the BHM NWS office...
NOUS44 KBMX 012042
PNSBMX
ALZ011>015-017>050-012145-
PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
345 PM CDT WED JUN 1 2005
...TODAY IS NOT ONLY THE BEGINNING OF THE 2005 HURRICANE SEASON...BUT ALSO THE START OF CENTRAL ALABAMA'S WET MICROBURST SEASON...
MOST PEOPLE ARE AWARE OF THE DESTRUCTIVE FORCES OF HURRICANES...BUT FAR LESS ARE AWARE OF THE DANGEROUS PHENOMENON KNOWN AS A MICROBURST. A MICROBURST IS SIMPLY A RAPIDLY DESCENDING COLUMN OF AIR...ASSOCIATED WITH A THUNDERSTORM...2.5 MILES OR LESS IN DIAMETER...LASTING FOR JUST A FEW MINUTES. MICROBURST WINDS CAN REACH SPEEDS EQUIVALENT TO A CATEGORY 3 HURRICANE...AND PRODUCE SIMILAR DAMAGE...BUT ON A MUCH SMALLER SCALE. DUE TO THIS SMALL SCALE...DAMAGE PRODUCED BY MICROBURSTS IS OFTEN MISTAKEN FOR TORNADO DAMAGE.
MICROBURSTS COME IN TWO FORMS...WET AND DRY. HERE IN CENTRAL
ALABAMA...DRY MICROBURSTS ARE VIRTUALLY NON-EXISTENT...MAINLY DUE TO OUR PROXIMITY TO AN ABUNDANT MOISTURE SUPPLY...THE GULF OF MEXICO. ALL MICROBURSTS ARE INITIATED BY COLD AIR DESCENDING FROM A THUNDERSTORM. THE KEY DIFFERENCE BETWEEN WET AND DRY MICROBURSTS IS IN THE MEANS BY WHICH THEY PROPAGATE TO THE SURFACE. DRY MICROBURSTS ARE FUELED ALMOST EXCLUSIVELY BY DRY AIR ENTRAINMENT... WHILE WET MICROBURSTS ARE A PRODUCT OF PRECIPITATION LOADING... ENHANCED BY DRY AIR ENTRAINMENT.
SOME INTERESTING FACTS/STATISTICS CONCERNING WET MICROBURSTS:
-WET MICROBURSTS ACCOUNT FOR UP TO 70% OF ALL WIND RELATED SEVERE WEATHER EVENTS IN ALABAMA DURING THE PERIOD FROM JUNE THROUGH SEPTEMBER.
-THE PEAK TIME FOR THE OCCURRENCE FOR MICROBURSTS IS AROUND 4 PM CDT.
-MICROBURSTS HAVE A FAIRLY EVEN GEOGRAPHICAL DISTRIBUTION AROUND THE STATE.
ALTHOUGH THERE IS NO "OFFICIAL" END TO THE WET MICROBURST SEASON IN CENTRAL ALABAMA...IT GENERALLY ENDS AFTER THE PASSAGE OF THE FIRST COUPLE OF COLD FRONTS IN SEPTEMBER. HURRICANE SEASON ENDS ON NOVEMBER 30.
THE 2005 HURRICANE SEASON IS EXPECTED TO BE MORE ACTIVE THAN
AVERAGE ACCORDING TO THE LATEST PREDICTIONS BY THE NATIONAL HURRICANE CENTER. TWELVE TO FIFTEEN TROPICAL STORMS ARE EXPECTED...SEVEN TO NINE BECOMING HURRICANES.
FURTHERMORE...THREE ARE EXPECTED TO ATTAIN MAJOR HURRICANE STATUS...A CATEGORY 3 OR HIGHER. LONG-TERM AVERAGES FOR THE NUMBER OF TROPICAL STORMS AND HURRICANES ARE TEN AND SIX...RESPECTIVELY.
NOUS44 KBMX 012042
PNSBMX
ALZ011>015-017>050-012145-
PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE BIRMINGHAM AL
345 PM CDT WED JUN 1 2005
...TODAY IS NOT ONLY THE BEGINNING OF THE 2005 HURRICANE SEASON...BUT ALSO THE START OF CENTRAL ALABAMA'S WET MICROBURST SEASON...
MOST PEOPLE ARE AWARE OF THE DESTRUCTIVE FORCES OF HURRICANES...BUT FAR LESS ARE AWARE OF THE DANGEROUS PHENOMENON KNOWN AS A MICROBURST. A MICROBURST IS SIMPLY A RAPIDLY DESCENDING COLUMN OF AIR...ASSOCIATED WITH A THUNDERSTORM...2.5 MILES OR LESS IN DIAMETER...LASTING FOR JUST A FEW MINUTES. MICROBURST WINDS CAN REACH SPEEDS EQUIVALENT TO A CATEGORY 3 HURRICANE...AND PRODUCE SIMILAR DAMAGE...BUT ON A MUCH SMALLER SCALE. DUE TO THIS SMALL SCALE...DAMAGE PRODUCED BY MICROBURSTS IS OFTEN MISTAKEN FOR TORNADO DAMAGE.
MICROBURSTS COME IN TWO FORMS...WET AND DRY. HERE IN CENTRAL
ALABAMA...DRY MICROBURSTS ARE VIRTUALLY NON-EXISTENT...MAINLY DUE TO OUR PROXIMITY TO AN ABUNDANT MOISTURE SUPPLY...THE GULF OF MEXICO. ALL MICROBURSTS ARE INITIATED BY COLD AIR DESCENDING FROM A THUNDERSTORM. THE KEY DIFFERENCE BETWEEN WET AND DRY MICROBURSTS IS IN THE MEANS BY WHICH THEY PROPAGATE TO THE SURFACE. DRY MICROBURSTS ARE FUELED ALMOST EXCLUSIVELY BY DRY AIR ENTRAINMENT... WHILE WET MICROBURSTS ARE A PRODUCT OF PRECIPITATION LOADING... ENHANCED BY DRY AIR ENTRAINMENT.
SOME INTERESTING FACTS/STATISTICS CONCERNING WET MICROBURSTS:
-WET MICROBURSTS ACCOUNT FOR UP TO 70% OF ALL WIND RELATED SEVERE WEATHER EVENTS IN ALABAMA DURING THE PERIOD FROM JUNE THROUGH SEPTEMBER.
-THE PEAK TIME FOR THE OCCURRENCE FOR MICROBURSTS IS AROUND 4 PM CDT.
-MICROBURSTS HAVE A FAIRLY EVEN GEOGRAPHICAL DISTRIBUTION AROUND THE STATE.
ALTHOUGH THERE IS NO "OFFICIAL" END TO THE WET MICROBURST SEASON IN CENTRAL ALABAMA...IT GENERALLY ENDS AFTER THE PASSAGE OF THE FIRST COUPLE OF COLD FRONTS IN SEPTEMBER. HURRICANE SEASON ENDS ON NOVEMBER 30.
THE 2005 HURRICANE SEASON IS EXPECTED TO BE MORE ACTIVE THAN
AVERAGE ACCORDING TO THE LATEST PREDICTIONS BY THE NATIONAL HURRICANE CENTER. TWELVE TO FIFTEEN TROPICAL STORMS ARE EXPECTED...SEVEN TO NINE BECOMING HURRICANES.
FURTHERMORE...THREE ARE EXPECTED TO ATTAIN MAJOR HURRICANE STATUS...A CATEGORY 3 OR HIGHER. LONG-TERM AVERAGES FOR THE NUMBER OF TROPICAL STORMS AND HURRICANES ARE TEN AND SIX...RESPECTIVELY.