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Area forecast discussion for the Florida Keys 
National Weather Service Key West Florida 
314 am EST Thursday Jan 8 2009 


Discussion... 
currently... 
skies cleared gradually in the Keys overnight following yesterdays 
frontal passage. It looks like rain amounts were generally less than 
a half inch. Temperatures stabilized in the upper 60s with light 
northeast winds. 


Our radar showed a line of diminishing showers in The Straits about 
30 miles off Key Largo at press time. These probably marked the 
location of the frontal boundary. 
&& 


Analysis... 
the front was fairly well-behaved. It came through on time at the 
right intensity...but the rain was reinforced by a second line of 
showers which developed out ahead of it and then merged in the 
vicinity of the Lower Keys. In the satellite imagery the advance line 
looked like it was triggered or enhanced by the passage of a train of 
Gravity waves. This worked in our favor and probably doubled our 
rainfall totals. 


Now that this feature is departing we have regional high pressure 
building into the Gulf. This should give US northwest winds veering 
north with time...but strong decoupling and nocturnal cooling on the 
Mainland has produced a local-scale bubble-high which is bringing our 
wind into the northeast this morning. This should wash out by middle-morning 
allowing the northerly synoptic flow to predominate thus producing 
backing winds locally -- a minor complication. 
&& 


Forecasts... 
for the next few days the Gulf high will be in control of our 
weather. As it slips east into the Atlantic our north winds will 
become east and this means a return to near-normal temperatures and 
rain chances for the rest of the week. 


By late Saturday another cool front will be approaching. Our guidance 
stalls it in The Straits through Monday and then washes it out or 
just loses it out there. Typically this means a spell of cloudy skies 
with sprinkles or light rain. 


For the remainder of the forecast period a return to dry anticyclonic 
conditions is indicated. 
&& 


Marine... 
we have had few observations of conditions in The Straits. The cman 
platforms on the reef show northeast winds less than 10 knots but 
this is representative only of local conditions. Given the line of 
showers on radar...we can deduce that winds will be more variable out 
beyond 20 miles from shore. Winds will become more regular as the 
showers move farther off shore and the peninsula-high erodes with 
daytime heating. 


In any case the conditions look good for recreational boating today 
so long as you don't go too far out. 
&& 


Aviation... 
VFR conditions will prevail today at the Key West and Marathon 
island terminals. There is a slim chance for patchy fog to develop 
during the pre-dawn hours into early this morning due to the 
combination of leftover moisture from yesterday's rain and near calm 
surface winds...but this probability is too remote to mention in the 
tafs at this point. Otherwise...middle and high level cloudiness will 
gradually give way to mostly sunny conditions today as the cold 
front moves further away from the area into the Bahamas. Light and 
variable winds early this morning will become northwest to north and 
increase to near 10 knots by midday. 
&& 


Temperatures and probability of precipitation... 
Key West 74 63 74 65 / 05 05 05 05 
Marathon 75 63 74 65 / 05 05 05 05 
&& 


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


$$ 


Public/marine.........Dfm 
aviation/nowcasts.....Apa 


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