"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".

Tuesday, July 5, 2011

Low Chance of Showers Today With an Increase Far South Wednesday

FLORIDA WEATHER TO BE DICTATED BY TROPICAL MOISTURE SURGES (AND LACK THEREOF) THROUGH MID PORTIONS OF NEXT WEEK. The first of which could start to affect South Florida later on Wednesday and most of the east and mid-portions of the state by later Thursday into Friday

TODAY: Overall, not much change from how the day closed out at sunset yesterday. The greatest band of concentrated moisture remains just along and south of "The Great Divide" of Dead Central Florida south of the Beach Line to Orlando and then south of I-4 from Orlando to Tampa Bay.  This divide was mentioned throughout posts most of the winter months as well. 

The greatest concentration is over South Central Florida arcing SE ward toward Miami and the Florida Keys. There is two pronounced "dry slights" in the mid-levels, which seem to be a result of subsidence (sinking air) ahead of an inverted trough (tropical wave) as shown in the image above.  

Net affect of subsidence (sinking air) and continued 'dry slots' (more pronounced than yesterday) will be significantly less showers and thunder today, as already indicated by the lack of early morning activity over South Florida and zero cumulus outside of my location at this hour...if even a cloud.

The only areas at this hour which hold any potential for a shower based on early day instability are near Cape Canaveral and the Keys (oddly, the two driest locations in the summer months); however, at Cape Canaveral the dry slot is affecting the mid levels as indicated by the morning XMR (KSC landing strip) sounding  which shows lack of moisture above 15,000 ft. The Panhandle region is under a totally different synoptic scale regime altogether, and holds the most promise for some isolated thunderstorms today. The Tampa Bay area, although sketched in above as well as SW Florida remains a bit sketchy. That given:
TODAY: I'm opting to lean toward the Devil's Advocate for those who like showers and thunderstorms to cool off  in during the late afternoon hours now that we are in full bore summer. I've seen the forecasts discussions and will opt out to downplay the day for a change. Maybe I'm just in a bad mood. Markings indicate where rain/thunder chances
could exist today from mid-afternoon through sunset at some time or another.

NOTE: There is plentiful moisture in the low-mid-levels over much of South and South Central Florida at this time, but believe most of that could remain trapped below 15,000 ft, which means nothing more than a brief shower could form over that area in the presence of warm, tropical air aloft. It's definitely not the 'convective season' any more, when cold air aloft is present, and the day could otherwise result in some strong but isolated thunderstorms.

TOMORROW: Appears the first hints of the tropical wave will be recognized over South Florida to near Lake Okeechobee by late in the day. Again, down playing the forecasts (mainly for Central Florida) until indicators come in greater agreement. Often, these systems are  often over-hyped, so going with climatological experience and persistence rather than what one model shows.

THURSDAY: By this day, most of the east coast form near Daytona to the Keys will be recognizing the dampening out wave as it breaks ashore in the form of showers, being as that this area will be first to no longer by under the leading, subsidence side of the trough coupled with deep layer moisture. 

FRIDAY-SATURDAY: These days could be dictated by early day showers evolving into thunderstorms by noon time through sunset over much of the peninsula. The wave, or what is left of it, could start to rotate NNW ward toward the panhandle and other parts of the Deep South.

Beyond Sunday and/or Monday it gets quite sketchy with the GFS taking moisture levels down, with a ridge axis across Dead Central. This would normally dictate afternoon and early evening thunderstorms, mostly along the I-4 corridor and over inland South Florida; however, guidance is painting the rain chances to be quite meager other than over North Florida.  Just have to see how things evolve at this early stage.

SIDE BAR: It is worth mention that the overnight NAM model shows VERY LITTLE to NO RAIN with this system that is approaching over the state. It instead shunts most if not all of the ACTIVE moisture well north and east of the state, leaving the state proper under moist but subsiding air, non-conducive for even a shower to form. So far, this is an outlier.. being  a significant change from previous output, but bears considering. 

On the other-hand, the GFS overnight was constant from previous runs. The only difference overnight was that the axis of greatest rainfall was shifted a bit further east toward the East Side of the state rather than right over the interior and west side. Overall, South Florida does not seem to be impacted either way with the change in the GFS, with rain chances looking quite good either way (outside of the NAM of last night's run).

SHUTTLE LAUNCH: It still appears (as it has for over a week now), based on the pessimistic chance of higher rain chances, that the Launch holds to be delayed due to weather, if not only due to cloud coverage. High PWAT air tends to hold cloud coverage overnight, slow to burn off. With some good rains in the vicinity by late Thursday looking probable, and very high PWAT air over 2.15"...clouds could be a factor and/or developing convective type rain-showers. On the other hand, there's always the NAM calling for sunny skies! ;-0. Then there's the last option that it will be able to go, but with significant clouds coverage making those 2000-$5000 dollar ticket sales terribly expensive for 20 seconds of eye-candy time.

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