"But seeing they could not See; hearing they could not Hear"
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"From its chamber comes the whirlwind, and cold from the scattering winds." - Job 37:9.

"The wind blows to the south and turns to the north; round and round it goes, ever returning on its course".

Wednesday, February 16, 2011

Cloudy East/North Coast, Showers, Pleasant Elsewhere

Images This Morning: 1)Dotted yellow line shows what remains of the old 'back door' frontal boundary (see discussion below) and green areas show shower chances first part of today (dashed shows working into tomorrow) - also shown is a weak thermal low near Cape Canaveral; (2) 2M dew points at 9AM-yellow is highest dew point temperatures (3) Convective available Potential Energy (CAPE) values show highest CAPE just offshore the Cape (these are meager values, but nonetheless, exists\ there and are acting as a 'source region' for shower generation).

NOW: What remains of the inverted back door cold front discussed yesterday is positioned approximately as shown in the first image above. It never really made it as far south as was feared it would yesterday. As such, the Cape area never got 'back doored' by very cool marine air. It made it about as far south as the tip of the Cape where late afternoon temperatures went down to 59F...too close for comfort for folks in Cape Canaveral south. At that same time it was 68F degrees on my porch not far away. As noted above, the boundary made it about as far south as the tip of the Cape at KSC where it resides this morning. pushing inland across the St. Johns River Valley Basin of NE Florida. As we can see from from this satellite image, extensive low level cloudiness exits along and behind the boundary where richer dew-points (more moisture) resides.
Also noted this morning is a very very weak surface 'low pressure circulation' in the armpit of the Cape near Cape Canaveral to Cocoa Beach north of SR 520. This circulation will likely wash out during the late morning hours as it seems to be a function of ocean temperature differences between those measured north of the Cape versus those south of the Cape in an otherwise near calm wind environment. We also see the highest CAPE values offshore the cape (which are in part a function of dew-points and lapse rates). With the greatest instability (highest CAPE values) in that location, extensive low level clouds and light rain showers have been forming and moving onshore from the tip of the Cape northwestward within the bounds of the solid green line. In essence, this area is acting as a 'source region', at least early today. We'll see some changes in this configuration as pictured now as the day wears on.

A weak mid-upper level trough is passing over the North half of Florida this afternoon and across this surface boundary from west to east. This could, at a minimum, provide enough continued lift for more clouds and showers in a broader expanse than what I'm seeing now, but otherwise impacts remain minimal.

As I type this morning, with the sun having risen, cloudiness overhead my location has thickened - a drop or two of rain could come down at just about any time now. For the most part, any rain to fall today will be north of SR520 along and east of US1 through the earlier portions of the day, but that area should spread westward as shown by the dashed green line in the first image as the boundary tries to push on shore, more so in NE Florida where high pressure off the Carolinas has a greater influence there to push the boundary inland. Think that any rainfall "totals" would be 0.1" or less. Additionally, most of the rain through early afternoon to fall will be east of I-95 north of Cape Canaveral.

Otherwise, temperatures underneath the clouds today probably won't break 70F degrees, whereas the remainder of the state will reach the mid to low end upper 70s under partly cloudy skies. Overnight lows as expected fell into the mid-50s in general most areas, with the coolest reading at Tallahassee at 36F and along interior portions of the West Coast where temperatures were in the 40s. Some of those same areas today will also be the warmest though with less clouds and a land breeze north of Sarasota. Coastal lows from JAX to Miami were 57F-63F in general.

TONIGHT: As high pressure builds a bit further south and the near shore Atlantic surface winds become more ESE, but remain light (10 mph or less), stronger offshore. Could see some regeneration of the coastal trough along the immediate coast from Jupiter Inlet north, and as the story goes, continued cloudiness overnight into early Thursday with a slight chance of a light rain shower within the area shown in the dashed green lines into tomorrow under those clouds. Rainfall, again, will be very light. Coastal lows in the 60s, mid-upper 50s inland. Very small chance of a spit from near Boynton Beach south as well tomorrow as the coastal trough develops overnight, but very minimal.

TOMORROW: Should start off the day over all of East Florida (namely east of i-95) as noted above through early afternoon. Looks like, as it stands now, with daytime heating or by early afternoon the trough will washout. Temperatures similar to today's. But just exactly when this will occur remains to be known, but it should be sometime tomorrow before high pressure strengthens across the Gulf and Florida, absorbing the boundary in the process.

FRIDAY-EARLY NEXT WEEK: Not seeing anything other than high pressure over the Gulf and Florida with no boundaries (other than thermally induced coastal ones on both coasts) under high pressure in the mid-upper levels. High pressure center aloft could shift more toward the Florida Straits going into late weekend as 500mb heights rise due to warmer air in the mid-levels moving in which would cap off any lifting mechanisms that would induce showers otherwise. Thus, after tomorrow (sometime) it looks rain free. Coolest afternoons along A1A up and down the coast, but also warmest overnights there as well.

Afternoon highs along A1A from Cape Canaveral north around 68F -73F, peaking out early in the afternoon before a light sea breeze sets in. Overnight lows from Cape Canaveral south in the low 60s warming to the mid-upper 60s south of Ft Pierce going into the weekend. By the weekend morning lows from West Palm South might never get below 70F, essentially equaling the water temperature. Afternoon highs will also get into the low 80s on various days late weekend going into next week in the locally preferred areas on any given day, but those areas will likely have to be at least 1/2 mile from the coast.

Very generally, temperatures will be close to normal afternoon highs/lows everywhere whereas the immediate coast could be above normal by 4-8F degrees for morning lows. Very little in the wind department, less than 12mph throughout the time frame.

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