Area Forecast Discussion
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FXUS62 KKEY 191457

Area Forecast Discussion
National Weather Service Key West FL
957 AM EST Thu Jan 19 2017

.DISCUSSION...In the middle to the upper levels(700-200 mb),
latest available satelitte imagery as of 900 am overlaid with
model streamline analysis depict the development of a deepening
powerful middle and upper level cyclone centered over Kansas.
Downstream of that feature, the northern axis of a deep and warm
anticyclone pokes unseasonably far northward towards the Lower
Great Lakes Region from a center near Central America. A very
strong middle and upper convergence zone exists in the interface
between these features, and is evident by a zone of 100 to 150
knot winds at 250 mb and 50 to 75 knot at 500 mb winds that
presently extends from Central Old Mexico northeastwards to the
Mid-Mississippi Valley thence eastwards to off of the Mid-Atlantic
Coast. South Florida and the Keys are beneath very warm and dry

At the surface and in the lower to middle levels, (Surface to 700
mb). Latest available marine and land surface observations and
surface analysis as of 900 am details a complex low pressure
system developing along a frontal system from the Southern
Mississippi Valley to East Texas. West of that, another low
pressure system is developing along the Southern Frontal Range
over Northern New Mexico. Closer to the Keys, there is a weak 1020
mb surface ridge axis from the Central Bahamas to Central
Florida. As a result, the 12Z sounding at Key West illustrated a
light and veering flow from the surface to 875 mb, with a 2-3
degree C inversion from 870 to 865 mb. So overall the column was
quite dry.

.CURRENTLY...As of 900 am, Skies are mostly sunny across the Keys
Island Chain and the adjoining waters. Temperatures have reached
the lower to middle 70s with dewpoints in the middle 60s. C-man
stations are recording variable winds at 5 to 10 knots and sensors
showing NW TO NE winds at 5 to 10 mph over the islands.

.SHORT TERM...Deep middle and upper level ridging in combination
with surface ridging in close proximity to the Keys will lend
itself to both excellent land and sea weather, with great boating
conditions today through tomorrow night. No chance for measurable
rainfall is indicated given the dearth of dry air in the lower to
middle levels. Looking towards the weekend, mariners and residents
will need to pay attention due to the arrival of a powerful cold
front which will likely be preceded by a significant squall which
will be moving from west to east across the Keys and surrounding
waters late this upcoming weekend. More on that this afternoon.
No changes this morning.


.MARINE...No headlines are expected today through Saturday.
Excellent boating conditions today through Friday night. A cold
front will dive across the Gulf of Mexico Saturday night, arriving
near the Keys area Sunday night. Winds will increase on Sunday
out of the south, turning southwest and becoming strong after
midnight. A small craft advisory is likely for all Keys waters
Sunday night. A squall line will likely lead the cold front and
will be the at the time of the initial wind surge. The cold front
will trek northeast away from South Florida and the Keys Monday
night as quickly as it arrived. Winds will relax on Tuesday and
the advisory flag will be lowered.


VFR conditions will continue for EYW & MTH through at least the 24
hour period. Expect light to gentle breezes, with winds veering from
the east-northeast to the southeast this afternoon.


On this date in 1997, a low temperature of 48 degrees was recorded
at the Key West International Airport. This set the daily record for
low temperature in Key West for January 19th. Temperature records
for Key West date back to 1872.




Upper Air/Data Collection......Vickery

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