Expert: Donald Rosenfeld - 2/28/2004

Question
Hi Don,

Just recently the NWS issued a PNS stating that we have had 6 straight days of 100% sunshine here in Vermont
(see below). Although not a record they did point out that this is a very rare occurence indeed!  Now this is for BTV but as you might imagine it has been pretty clear here in Lamoille county of Vermont as well!  We have always known that we get long streaks without sun, but some state that we as a county are the 2nd cloudiest county in the country.  I have no idea where they get this statistic from but I do know that it is very cloudy here in November and December and that we are often cloudy when Burlington is not due to the fact that we are in a mountain location.  So what gives?  Is Lamoille county really that cloudy?  And where can I find info that would lead me to conclude that.  Also, as an ne.weather fan, I can safely say that I enjoy your battle against the moderated group!
421
NOUS41 KBTV 282317
PNSBTV
NYZ026>031-034-035-087-VTZ001>012-016>019-290500-

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE BURLINGTON VT
617 PM EST SAT FEB 28 2004

...3RD SUNNIEST STRETCH REPORTED IN BURLINGTON VERMONT...

THE NATIONAL WEATHER SERVICE IN BURLINGTON VERMONT HAS RECORDED ITS
6TH DAY IN A ROW OF 100 PERCENT POSSIBLE SUNSHINE.  THIS MAKES IT THE
THIRD SUNNIEST PERIOD DATING BACK TO 1940.  THE TIME PERIODS OF
OCTOBER 13TH THROUGH THE 18TH IN 1961 AND OCTOBER 3RD THROUGH THE 8TH
IN 1946 WERE ALSO PERIODS OF 6 DAYS IN A ROW OF 100 PERCENT POSSIBLE
SUNSHINE.

THE RECORD NUMBER OF DAYS WITH 100 PERCENT POSSIBLE SUNSHINE IS
9...WHICH OCCURRED FROM SEPTEMBER 12TH THROUGH THE 20TH IN 1946.  THE
SECOND HIGHEST CONSECUTIVE DAY PERIOD OF 100 PERCENT POSSIBLE
SUNSHINE WAS MARCH 15TH THROUGH THE 21ST...ALSO IN 1946.

EVENSON/BREITBACH  

Answer
Hi Dave

I'd guess that the string of clear days are related to the positioning of the jet stream along with the reduction in air traffic since 911. Also, even though it is Vermont where the topography favors cumulus buildups, that would be  more of a summer function than winter.

As to county cloudiness statistics, I've never heard of a source of that data!

There are co-op stations that record cloudiness.

There are also databases of satellite composites.

Anyway, take a look at:

http://www.worldclimate.com/cgi-bin/grid.pl?gr=N44W072

http://ioc.unesco.org/oceanteacher/resourcekit/M3/Data/Datasets/MajorPublishers/...

http://www.gcrio.org/links/links4.htm

http://met-www.cit.cornell.edu/climate/Impacts.html

http://www.indiana.edu/~libgm/climatelist.html

http://directory.eoportal.org/info_NOAAsSatelliteActiveArchiveSAA.html