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fxus62 kkey 181829 
afdkey 


Area forecast discussion for the Florida Keys 
National Weather Service Key West Florida 
230 PM EDT Friday Jul 18 2008 


Discussion... 
currently... 
kbyx detects no precipitation echoes in the forecast area. Skies 
over the island chain are mostly sunny. Winds over land are 
southeast to south at 5 to 10 miles per hour. C-man winds...on average...are 
southeast to south at 5 to 10 knots. Temperatures are near 90 
degrees. Only about six degrees of cooling is expected tonight due 
to increasing east to southeast surface winds over water with 
temperatures in the middle 80s. 


Short term (tonight through Sunday night)... 
in the upper levels of the atmosphere...an area of low pressure will 
move westward across Cuba tonight and Saturday. A very dry air mass 
for this time of year...along the northern periphery of the upper 
level area of low pressure...will filter into the service area 
tonight. Precipitable water (pwat) values should fall below one and 
one half of an inch tonight. Precipitable water values should remain below one and 
one half of an inch Saturday. Due to the presence of this very dry 
air mass...nothing more than dime probability of precipitation are needed for tonight and 
Saturday. A tropical disturbance is located in the central Caribbean 
Sea. This tropical disturbance could develop into a tropical cyclone 
anytime as it moves to the west-northwest through the central and 
western Caribbean Sea. Atmospheric moisture will increase Saturday 
night as this tropical disturbance passes south of western Cuba. By 
sunrise Sunday...precipitable water values should be just above two inches. 
Increasing atmospheric moisture will lead to increasing rain chances 
Saturday night. The GFS numerical model indicates some large scale 
lift over the Florida Keys Sunday. Rain chances will be increased by 
10 percent for Sunday due to the possibility of synoptic scale 
ascent coupled with abundant atmospheric moisture in place. Precipitable water 
values may not fall below two inches until late Sunday night. Be 
that as it may...lack of large scale lift should limit probability of precipitation to low 
chance category Sunday night. 


Long term (monday through friday)... 
in the low to middle levels of the atmosphere...an Atlantic ridge of 
high pressure will extend across the Florida Peninsula Monday 
through Friday. In the upper levels of the atmosphere...an 
anticyclone will be centered in the vicinity of the northwest Gulf 
of Mexico Monday through Friday. The long term portion of the zone 
forecasts for the Florida Keys will be based on climatology. 


&& 


Marine... 
light to gentle breezes will become moderate out of the east or 
southeast overnight. No advisories or cautionary statements 
expected tonight and Saturday morning. Small craft are urged to 
exercise caution on Atlantic waters Saturday afternoon through 
Sunday night due to sustained east surface winds of 15 to 20 knots. 
Sustained east surface winds of 15 to 20 knots are possible on 
Atlantic waters Monday into Monday night. For now...wind speeds will 
be advertised just below 15 to 20 knots on Atlantic waters Monday 
and Monday night. No advisories or cautionary statements expected 
Tuesday and Wednesday. 


&& 


Aviation... 
this evening and overnight...light southeast winds from the surface 
to 15 kft should back to northeast between 22z and 24z...allowing 
for a cloud line to develop. Short-lived MVFR ceilings will be 
possible at both keyw and kmth island terminals. Isolated showers 
and thunderstorms will be possible overnight with brief IFR ceilings 
and/or visible. Surface winds will average from 100 degrees near 8 knots. 


&& 


Climate... 
on this date in Keys weather history...in 1881...the high 
temperature in Key West was 95 degrees. This set the daily record 
for maximum temperature measured in Key West on July 18th...a record 
which still stands 127 years later. 


&& 


Preliminary point temps/pops... 
Key West 83 90 82 89 / 10 10 30 40 
Marathon 83 92 82 91 / 10 10 30 40 


&& 


Key watches/warnings/advisories... 
Florida...none. 
GM...none. 


&& 


$$ 


Public/marine/fire/climate/digital...bs 
aviation/nowcasts....................futterman 
data acquisition.....................Dr 


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