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
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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. | ||
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