EYES ON THE TROPICS OCT 27, 2017 1004 PM EDT

000
ABNT20 KNHC 271123
TWOAT 

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Fri Oct 27 2017

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

Shower and thunderstorm activity has increased and become more
concentrated in association with a trough of low pressure over the
northwestern Caribbean Sea.  Environmental conditions are expected
to be conducive for development today and Saturday, and a tropical
depression could form as the system moves northward over the
northwestern Caribbean Sea.  Increasing upper-level winds will make
conditions less favorable when the system moves north of Cuba and
merges with a cold front on Sunday.  Interests in the Cayman Islands
and central and western Cuba should monitor the progress of this
system.  Regardless of development, this disturbance is expected to
produce locally heavy rainfall over the Cayman Islands, Jamaica,
and portions of Cuba during the next day or two.  These rains are
forecast to spread northward across portions of South Florida and
the Keys on Saturday, and over the northwestern Bahamas Saturday
night and Sunday.  An Air Force Reserve reconnaissance aircraft is
scheduled to investigate this system this afternoon, if necessary.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...medium...60 percent.

$$
Forecaster Brown

 http://ralphstropicalweather.myfreesites.net

 SEVERE THUNDERSTORM OUTLOOK

 SPC AC 270524

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1224 AM CDT Fri Oct 27 2017

   Valid 281200Z - 291200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER SOUTH
   FLORIDA...

   ...SUMMARY...
   Thunderstorms with at least a marginal risk of severe weather may
   impact southern Florida and the Keys late Saturday afternoon and
   evening.

   ...South Florida...

   A positive-tilt synoptic trough currently from the upper MS Valley
   to the southern Rockies will undergo further amplification. By 12Z
   Saturday this feature will extend from the Great Lakes to the lower
   MS Valley and will advance slowly east during the day. Downstream
   cold front will stretch from a surface low over the Great Lakes to
   the central Gulf early Saturday and approach the Atlantic seaboard
   by the end of this period. Preceding the upper trough, a
   southern-stream perturbation accompanied by a weak surface low will
   emerge from the Caribbean. A warm front will lift north through
   southern FL in advance of the low with near 70F dewpoints spreading
   inland contributing to destabilization. However, instability will
   remain weak owing to widespread clouds and areas of
   showers/thunderstorms. Surface-2 km hodograph size will increase by
   early evening over south FL in vicinity of the warm front as the
   low-level jet strengthens in association with the approaching
   surface low, though winds aloft will remain modest. Given the moist
   boundary layer and favorable low-level wind profiles expected to
   evolve by Saturday evening, some potential exists for convection
   developing in this environment to produce a couple of brief
   tornadoes. The anticipated weak thermodynamic environment precludes
   more than a marginal risk category at this time. 

HYDROLOGIC OUTLOOK 

Event:	Hydrologic Outlook
Alert:	...HEAVY RAINFALL POSSIBLE OVER SOUTH FLORIDA SATURDAY INTO SATURDAY NIGHT... A tropical disturbance over the Western Caribbean Sea is forecast by the National Hurricane Center (NHC) to move slowly north northeast and be near South Florida on Saturday. This disturbance will bring deep tropical moisture to the area leading to numerous showers and scattered thunderstorms with heavy rainfall, mainly Saturday and Saturday night. Total rainfall amounts are forecast to be between 2 to 4 inches with locally higher amounts with any training thunderstorms. If this trend continues for South Florida, then a Flood Watch may be needed later today or tonight for Saturday.
Instructions:
Target Area:	Coastal Broward County Coastal Collier County Coastal Miami Dade County Coastal Palm Beach County Far South Miami-Dade County Glades Hendry Inland Broward County Inland Collier County Inland Miami-Dade County Inland Palm Beach County Mainland Monroe Metro Broward County Metro Palm Beach County Metropolitan Miami Dade