Fall Weather Coming Next Week

[PTrackerLA]

Looks like the deep south could see a true transition into fall next week. Bring on the cool temps and the end of cane season! This discussion also talks about possible impacts if Mt. St Helens erupts; could be some interesting times ahead.

New Orleans NWS AFD

LONG TERM DISSUSION...
LOOKING AT THE UPPER LEVEL PATTERN DEVELOPING OVER THE NORTH
AMERICAN CONTINENT SHOWS A RELATIVELY HIGH FREQUENCY SHORTWAVE
PATTERN WITH AUTUMNAL AIR POSED IN THE CANADIAN PACIFIC AREA. ONE
FRONT MOVES INTO THE FORECAST AREA WITH A MODERATING SURGE OF HIGH
PRESSURE BUILDING INTO THE REGION AT THE SURFACE. ZONAL FLOW ALOFT
MAY NOT ALLOW A CLEAN SWEEP OF THE SKY AS THE NEXT SHORTWAVE
AMPLIFIES TO OUR WEST AND BRINGS ANOTHER FRONT THROUGH THE AREA FOR
LATE MONDAY. TEMPERATURES SHOULD SLOWLY LOWER WITH EACH PASSAGE BUT
CONSIDERABLY COOLER AIR WILL LIKELY HOLD OFF UNTIL AFTER A
HEMISPHERIC LONGWAVE TROUGH ROTATES THROUGH THE GULF OF ALASKA TO
ESTABLISH A LONG FETCHED NORTHWEST FLOW PATTERN INTO THE U.S. FOR
THE LATTER HALF OF NEXT WEEK. THIS SHOULD BE THE ONSET OF AUTUMN
FEEL AIR FOR THE DEEP SOUTH.

&&

.CLIMATE INFORMATION...
ACCORDING TO VOLCANOLOGISTS THE MOUNT ST. HELENS IS EXHIBITING AN
INCREASE IN SEISMIC ACTIVITY WITH AN INDICATION OF STEAM OR MAGMA
BUILDUP IN THE CULDRON. THIS COULD BE A NEWSMAKER IN THE UPCOMING
WEEKS AND MAY PLAY A SIGNIFICANT ROLE IN CLIMATE CHANGE DOWNSTREAM
IF IT INDEED ERUPTS...INCLUSIVE OF IMPACTS TO LOCAL WEATHER AFFECTS
IN UPCOMING MONTHS. THIS WILL BE CLOSELY MONITORED IN THE UPCOMING
WEEKS.

[storm4u]

.CLIMATE INFORMATION...
ACCORDING TO VOLCANOLOGISTS THE MOUNT ST. HELENS IS EXHIBITING AN
INCREASE IN SEISMIC ACTIVITY WITH AN INDICATION OF STEAM OR MAGMA
BUILDUP IN THE CULDRON. THIS COULD BE A NEWSMAKER IN THE UPCOMING
WEEKS AND MAY PLAY A SIGNIFICANT ROLE IN CLIMATE CHANGE DOWNSTREAM
IF IT INDEED ERUPTS...INCLUSIVE OF IMPACTS TO LOCAL WEATHER AFFECTS
IN UPCOMING MONTHS. THIS WILL BE CLOSELY MONITORED IN THE UPCOMING
WEEKS.[/quote]

Whats that all about and what kind of changes would there be!

[PurdueWx80]

More than likely, there would be few effects from the type of blast expected - less solar radiation can get to the surface because of all the ash/gas/particles in the air, but it takes a really big explosion to do this. The amount of CO2 and other greenhouse gases released shouldn't be enough to cause a warmup. Here is an article from NASA concerning the effects of the 1980 eruption on climate. I think the NOLA NWS went a little overboard in their statement.

http://www.gsfc.nasa.gov/gsfc/educ/scie ... 050696.htm