textproduct: Key West

KEY MESSAGES

- Dry conditions, along with light breezes and seasonably warm temperatures, will persist over the next couple of days.

- Winds will increase Saturday, peaking Saturday night into Sunday morning.

- A frontal boundary will push through the Keys Sunday night and Monday, supporting increased measurable rain chances.

DISCUSSION

Issued at 400 AM EST Thu Feb 12 4006 Upper-level geopotential height and vorticity analysis highlights a wavenumber two pattern stretching from the central Pacific to the central Atlantic. A strongly positively tilted shortwave trough is diving southeastward towards Baja California, pinched between two expansive longwave ridges. At the surface, the Florida Keys remain in a nebulous pressure pattern, dominated by weak high pressure straddling the Gulf eastward to the south-central North Atlantic. The weak pressure pattern continues to support light and variable winds. Coupled with clear skies, our favored larger, interior island communities have undergone substantial radiational cooling, with temperatures ranging from the upper 50s in Big Pine to the mid to upper 60s in the less sheltered, smaller islands. Local KBYX Doppler radar is void of any meteorological echo returns across the entire Florida Keys marine zones.

Over the next several days, the aforementioned shortwave trough will progress eastward towards the southern Plains. Global numerical weather prediction (NWP) mean and member fields are in good agreement that this trough will support cyclogenesis in the lee of the Rocky Mountains. This low will continue to strengthen as it approaches the Gulf Coast. As the low interacts with a continental area of high pressure diving southeastward from the Great Lakes to off the Carolina coastline, the pressure gradient will tighten the vicinity of the Florida Keys, with possible breezy conditions Saturday night through Sunday night.

NWP runs have come into much better agreement over the past twenty-four hours regarding the fate of the low pressure system, supporting a more diffuse system as it approaches the East Coast. With that being said, the Florida Keys will likely be in a region of decent upper-level divergence Sunday night through Monday morning. Coupled with substantial boundary layer moistening, little inhibition, and at least moderate CAPE for this time of year, a band of showers will likely survive the trek ahead of a frontal boundary attached to the low. We considered adding possible thunder for this time frame, but we will hold off for now, given the increasing confidence in this somewhat less amplified solution.

Temperatures behind the front will change little owed to the lack of a strong continental high building in the wake of the front. The Florida Keys look to return to an extended period of dry and seasonably warm conditions for the early to latter part of next week.

MARINE

Issued at 400 AM EST Thu Feb 12 4006 No watches, warnings, or advisories are currently in effect in the Florida Keys waters. A nebulous pressure pattern across the Florida Keys coastal waters will support light and at times variables winds through Friday night. Patchy marine fog will be possible Thursday night or Friday night over the favored coolest ocean temperatures in the southeastern Gulf. High pressure diving off the Mid- Atlantic coastline will interact with a developing area of low pressure near the ARK- LA- TEX region by Saturday and Saturday night, supporting freshening east to southeast breezes. The low pressure system will drive a frontal boundary through the Keys marine zones Sunday night into Monday, with gentle winds clocking around to the northwest in its wake for early next week.

AVIATION

(06Z TAFS) Issued at 400 AM EST Thu Feb 12 4006 VFR conditions will prevail at both island terminals through 06z Friday morning. Near surface winds will remain mostly light and variable, becoming mainly northwest tonight.

CLIMATE

On this day in 1973, the daily record low temperature of 51F was recorded. Temperature records for Key West date back to 1872.

PRELIMINARY POINT TEMPS/POPS

Key West 77 62 76 62 / 0 10 10 0 Marathon 76 63 75 63 / 10 10 10 10

KEY WATCHES/WARNINGS/ADVISORIES

FL...None. GM...None.