Image: "Omega Block" pattern indicated by nearly cut-off low pressures aloft over the Ohio Valley and SW U.S. for Tuesday evening as forecast by the NAM model
MORNING RECAP: Weak frontal boundary passed through Florida yesterday afternoon and now resides near the Keys and into the Bahamas this morning. Graphical depictions and surface observations indicate a fairly classic drainage flow scenario in place for all but extreme S. Florida (over the Keys and the Southern Tip) where cloud conditions prevail over the Keys and extreme SW Florida. A narrow band of low/mid-level clouds is sweeping down the east coast just offshore, with some partly cloudy observations being observed along the landmass as the deepest extent of the clouds remains offshore now approaching Daytona Beach.
TEMPERATURES: Further south, the keys are socked in this morning where the front seems to have come to a halt, or at least slowed down quite a bit. Rain showers fall over the Florida Straits either along or south of this boundary, hard to say for sure. Meanwhile, coldest temperatures as one would expect are over the Extreme North/Western Florida Panhandle with, if you can believe, there's a Wind Chill Index (WCI) temperature of 43F (!) and ambient air temperature of 46F at Mary Esther at 7AM. Elsewhere, the extent of the coolest air (but not nearly as cool as that at Mary Esther) gives credence to drainage flow with temperatures as far south and west as Tampa to Punta Gorda; Tampa Exec. this morning just prior to sunrise is 57F and Punta Gorda and Okeechobee are 63F. In retrospect, despite the cloudy conditions over the Keys they are still the warmest with sunrise mercury readings just under 80F!
For comparisons sake, and to emphasize the affect of having close proximity to the near shore Atlantic Waters, Patrick AFB is 72F (my porch is 69F) where as Melbourne is 63F. That's nearly a ten degree difference just by crossing the Intracoastal. Sky at sunrise at my place is a cobalt blue clear with a light northwest wind right as the first hints of the rising sun become evident to the east. As was written about last winter, we will see the affect of the near shore waters at times having a distinct affect on A1A corridor temperatures almost every morning; 10 degree temperature differences between the I-95 Corridor and A1A are not unusual. Also, as is noted this morning, coldest morning temperatures over Central and South Florida are found in those same locations noted in the previous paragraph.
SYNOPSIS: As can be seen in the included image, an "Omega Blocking" pattern has been becoming established now for the past 48 hours and will continue through at least Wednesday. It is called an "Omega Block" because the pattern shown in the image of the two low pressure areas and the high pressure in-between resembles the Greek letter "Omega". These can last for several days or even a couple of weeks. Elsewhere, broad area of low pressure continues over the Caribbean and SW Atlantic over Puerto Rico and east of there. Invest 97L is located over Puerto Rico and ESE of there with a 20% chance of development. Another area of 10% interest is located even further east and south of 97L.
SYNOPSIS FORECAST: In this case, it appears the Omega Blocking pattern will last under a week, but needs to be watched. Models are known for trying to kick these patterns out too quickly, but from all appearances they seem to have a respectable reason for kicking out the low now over the Ohio Valley; after all, that low has been up there for nearly 48 hours already. This low will fill and be shifted to the E and ENE then eventually NE toward Eastern Nova Scotia as we head into late week as the low over the Desert SW Region begins to weaken and drifts only slowly east with time. Meanwhile in the short term, the Desert SW is enjoying a rather late season monsoonal rain event for them, with a slight risk of severe thunderstorms being issued for West Central Arizona tomorrow by the Storm Prediction Center. They are expecting some isolated strong storms today as well, mainly over extreme SE California, southern Nevada near Las Vegas and south into Arizona. A funnel cloud was sighted and filmed over S. Cal Saturday with flash flooding concurrent. This storm had slight rotation with it.
LOCALLY: As the low over the Ohio Valley kicks out winds aloft will become more westerly whereas surface winds will become progressively from a more northerly component and eventually NE component by later today and seemingly for eternity. Thickness values change little (the thickness between the 'standard' 500mb -1000mb levels). This thickness is determined by the average temperature between the two standard levels. Since thickness values change little, so will be the surface temperatures. Although, at the very lowest levels, that which we feel and read on the thermometer, temperatures will be begin a small warming trend most notable by morning low temperatures warming a bit beginning Tuesday along the coast and most all locations by Wednesday, with the result being temperatures around normal or perhaps a few degrees below 'normal', but no big deal.
MOISTURE/RAIN: The short term and extended period as far as clouds and rain are concerned are predominantly dry. Any influx of atmospheric moisture to the peninsula (other than the Keys) will be shallow and short-lived, and mostly limited to the east coast from Daytona to Miami. Things get a bit stickier from Ft. Lauderdale and points south, but will omit discussion for that region this morning. Either way one slices the pie, as noted, moisture will be limited to and below the 5000ft level, and its appearance will come in the form of periods of stratocumulus clouds and perhaps a light sprinkle detectable on the car windshield with nothing even measurable. It does not look like these periods would produce any more than partly cloudy to maybe mostly cloudy conditions when they do occur, but their presence should be relatively short lived (6 hours at most).
TROPICS: Invest 97L persists just east of Puerto Rico and shows an ever decreasing threat to anyone, including Bermuda. To exemplify a scenario painted by the latest GFS run, this system is expected to get booted post haste to the NE but some energy remains which continues to drift west toward Jamaica with time. As such, we might be seeing a new Invest area somewhere South of Jamaica over the weekend. But even still, if this system develops to the degree implied, the winds aloft over Florida and across the Gulf are easily from the west which would either sheer the system out or quickly give it a swift kick to its tropical butt way out there in time to the NE. Pure speculation. In essence, no tropical threats as things appear now through mid-October. On the other hand, some models show a threat to the Bahamas of a named system. Either way, no U.S. threats are indicated.