"But seeing they could not See; hearing they could not Hear"
“The views expressed herein are those of the author and do not necessarily represent those of the National Weather Service or affiliate/related organizations. Please consult .gov sites for official information”

"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".

Sunday, June 2, 2013

Pattern Change! - "Pandora's Box of Adverse Weather Watches" Later in the Week?


TODAY: The last post was Saturday a week ago which referenced the chance for a prolonged period of easterly winds, after a severe thunderstorm warning on the prior Thursday and then a rocket launch on Friday. On shore winds with periods of showers (mainly South Central and South Florida and toward the west side of the state (most notably yesterday) was the rule for several days. That pattern began to break down late Saturday and continues to break down as this is being typed. Note the light wind this morning.

High pressure to the east of the state is retreating to the east as a frontal boundary (which resulted in the Oklahoma City tornado traffic fiasco the other day, see images at end of post) progresses east but will never clear Florida.  Meanwhile, a broad and somewhat disorganized area of low pressure is to organize slowly over the next 48 hours in the Bay of Campeche with somewhat of a mid-level 'like' inverted trough to become more developed across the Central Florida region as noted above heading into Wednesday. (surface features will be a bit different). Now that we are caught up to the current time:

SUNDAY-TUESDAY: The short of all of this for today through Tuesday:  Better chances of thunderstorms as opposed to rain showers from early-mid afternoon, possibly lingering to well after dark as they decay after sunset. Steering currents today are already on the shift from west to east but very light and will unlikely be able to combat the east coast sea breeze, at least until early evening. Increasing moisture from the South could result in a number of showers and thunderstorms (mainly away from the immediate coast) although thunder might be audible from there. More likely some showers might be able to go up along the east coast sea breeze as it develops toward noon and onward making slow westward progress before meeting up with similar conditions from the west by mid-late afternoon over the interior. With a slow eastward push aloft, some of this activity might be able to make it to the immediate east coast just about anywhere along the Florida east coast by evening (or earlier toward South Florida) as the east coast sea breeze retreats back to the east coast.  Do note  that invariably each day will vary from one to the next so the "Day by Day" forecast blog post rule will apply through the week. Severe storms are not expected although a Special Weather Statement or two might become necessary for some stronger wind gusts and possibly some local flood statements due to slow storm motion and accumulating resultant rainfall.  

WEDNESDAY-FRIDAY: This is the most potentially volatile period as it stands this morning for a variety of reason which will only be briefly spelled out this morning due to the 'yet to develop' situation that has been captured by virtually all the forecast models in some form or another.

For today, I'm discounting the Canadian Model which shows a strong tropical storm moving into the Florida Big Bend later in the week.

Although, the 2AM (EDT) GFS is showing a Sub-tropical depression like low pressure area moving across the I-4 (which will be noted in imagery below).  The overall consensus though is for not one but two main areas of low pressure to cross the state from Central to North Central Florida from sometime overnight Wednesday toward Friday (with possibly smaller imbedded impulses as well). Timing might never be pegged down exactly but we'll spell out a few things that have been fairly consistent, then from that point we will be able to see how well our forecast models end up verifying in the coming days ahead.
1. A sub-tropical like low or series of lows (Perhaps a depression) will eject ENE-NE from near the NW tip of the Yucatan Peninsula toward Florida, highlighted and finalized by a more organized one at which point the 'show will be over'. It is the earlier stages of development of that final 'low' that is of most concern regarding a window of opportunity for brief tornadic/mini-supercell 'spin ups'. So far that window has been showing up from SW-W Florida and extending eastward and NE around the Wednesday-Wednesday night time frame into Thursday. Images below :

PRELIMINARY HEADS UP JUST IN CASE: The red box would be perhaps a tornado watch area with Flood watches as well being hoisted on the late Wednesday time frame. The lower left image is a depiction of the curvature of winds with height. Large looping hodographs would favor the tornado potential  which at this point is indicated by the red box above with other notes. Although that hodograph is not 'large' it is looped and it does get more 'interesting' toward a portion of South Central to the Beach line zone later in the period.

2. The more interesting thing that might be a fly-in-the-ointment is just exactly what if anything might develop as the upper level energy cross the Loop Current in the Eastern Gulf. The latest GFS is actually forming a weakly closed sub-tropical like Low pressure with winds of Tropical Depression to minimal Storm strength  Regardless of whether the system is named or not appears so far to be irrelevant unless we are in for a big surprise the next 72 hours. The fact remains that the GFS model has been showing this 'tornado' or strong wind gusts in mini-supercells (rotating thunderstorms) for quite a few days in a row now.

From the period of Early Thursday through Friday a "Pandora's Surprise Cache-Cash Award of Watch Boxes" might be in the making for accumulating rainfall of up to (dare we say 8 plus inches?) toward I-4? Do note, the Climate Prediction Center was highlighting South Florida just the other day for highest rainfall, but it contradicted another link on the same page that was showing further north (from what I could tell). The red area is of 'Overall " biggest interest as of this Sunday Morning for   tornado potential although all of the state mainly south of  I-10 will be in the cards of something interesting at varying times from late Wednesday into Early Friday.

3. To up the ante on a storm track which is shown by the black line above along that dashed line shown in the first image, the latest ECMWF model is finally available on this computer as of 4:40 AM Sunday morning. Noting that although this model is amped as the most reliable time and time again, it initially was taking a low into Louisiana  whereas the GFS has never once implied such a track.


The greatest tornado threat (if there is to be one) would NOT be under those lows but South and ahead of them..particularly as the first one moves in. The GFS and even the ECMWF have been 'implying' somewhat of warm front/cold front trough like system associated with the first low. It is along and preceding a pseudo-like warm front lifts northward from the Keys toward I-4 into Thursday-late Thursday  time frame so far that is most interest regarding that feature (which was reflected in the early image showing the hodograph).
So far, the biggest risk area begins toward SW Florida/Keys which lifts NE'tward to East Central Florida slowly with time.

4. GFS rainfall totals directly associated with those little 'vorticity maxes' have been tracking rainfall over a 24-48 hour time from of up to 8" (at least) for quite some time now generally along I-4 toward North Brevard County although there was a time when the track was across South Florida. Will this all change once again?  Quite possibly, although the time is drawing nigh and not once has the ECMWF tracked a disturbance across South Florida.

BEYOND: The system should be clipping the outer Carolinas just in time for another front and upper level trough which was shown in the very first image in this post to be pressing east. This will continue to keep the Atlantic High Pressure ridge axis suppressed across South to South Central Florida placing the state in a late afternoon thunderstorm / "Welcome Summer?"  Wet Regime like pattern up through the 12th of June which is a bit early, favoring the east side of the state for late afternoon thunderstorm activity.  

OTHERWISE: Discussions from a wide variety of forecast outlets are looking for an active tropical season. I'm watching the Northern Gulf and Florida particularly this year, not that it matters..but this area is long over-due climatologically speaking, especially South Florida (Miami/Dade) area for a "Big Named Storm".

TWITTER "TWEETS" regarding the other day in the Oklahoma City area  as the "High Speed Dirt"  flew not only along the ground but across the wires and the wireless.

No comments: