"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".

Saturday, March 19, 2011

Clear Sky (Florida) for Rare Super Perigee Full Moon - Equilux vs Equinox Revealed

Looking to see the Super Moon or more correctly the "Super Perigee Full Moon" tonight? Along the East Coast of Florida the moon will rise at 8:56PM EDT this evening as the moon approaches its closest orbit to earth during a full moon cycle. The graphic notes that the moon will be 14% larger; of course, the moon is not any larger, it just looks larger due to its closer approach (perigee) to earth. Conversely, an apogee moon will appear much smaller. We can get a better idea of perigee vs. apogee from this second image.

It's much easier to see here that the perigee is closer to earth than the apogee during the moon's orbit.  All in all, we might not be able to tell the difference other than during the first 2 hours of moonrise (8:56PM) and again an hour or two before moon set, Sunday morning at 7:42AM. During those times it is closer to the horizon and points of reference such as trees, buildings, mountains, power poles, etc. create the  illusion of the moon being 'larger' most dramatically.  So, if you miss it tonight and happen to be an early riser it will still look pretty cool between 6-7:30AM Sunday morning above the western horizon.

Coincidentally, as the Super Perigee Full Moon sets Sunday morning, we will be entering the Vernal Equinox as the sun will pass directly over the Equator on its way to the Summer Solstice (June 20/21) over the equator at 7:21PM EDT (2321 GMT) Sunday night, the Vernal Equinox (or so it's called). See why this might be considered a "myth".

Found a neat piece of info this morning that explains why I wrote  "a 'myth' revealed" in the title of today's post (at least in my mind). I'd always thought, and maybe you did too, that on the first day of Celestial Spring that days/nights are of equi (equal)-duration (hours/minutes), but I noticed this was not the case by pure coincidence, about two weeks ago. So I did some research.

This time of equal day/night length does not happen during the equinox, but rather during the "equiliux". Our days/nights were of equal length more than a week ago (the days are now longer by about 9 minutes). Additionally, from a technical perspective, it might be better to refer to this time of year as the "March Equinox" rather than Vernal Equinox. Vernal is the Latin derivative of "spring" (and it will not be spring in the Southern Hemisphere), so that faulty reasoning is obvious to the reader; for your info, equinox is Latin for 'equal night'. 
Again, although the word equinox is often understood to mean "equal [day and] night," this is not strictly true. For most locations on earth, there are two distinct identifiable days per year when the length of day and night are closest to being equal; those days are referred to as the "equiluxes" to distinguish them from the equinoxes. Equinoxes are points in time, but equiluxes are days. By convention, equiluxes are the days where sunrise and sunset are closest to being exactly 12 hours apart, and like I wrote above, this has already occurred here in Florida (can't speak for the rest of the country, but I'll gander this will not occur until later in Spring).
And another thing! Said with a light heart and mind of course, as written in several posts ago, spring in many parts of Florida from the meteorological perspective already began a few weeks ago, when  from this writer's perspective and other schools of thought, the average high temperature is equal to or greater than 75F (which of course varies with where on lives in the state). On a side note, the same school of thought infers that summer begins when the average high temperature in Florida meets 90F. This  has to vary in regard to the temperature threshold for the immediate coast though from my observation, because this average high temperature is never met along A1A where average highs during the summer are usually around 87F due to the prevailing SE winds blowing off ocean waters. It is interesting that for the most part, our big 'heat waves' (loosely written), occur not in summer but rather in spring. You know, those years when it gets near 100F degrees. These almost always occur before June 21st (the first celestial day of summer).  Based on this observation combined with the 'average high 0f 90F' reasoning,  Florida summer probably begins sometime toward the last week of May - First 10 days of June.
Now, that is based from a temperature perspective. Another way to look at (not of one of which I've read), is to herald summer in by when the diurnal daily thunder storm cycle begins, which considers all the variable atmospheric requisites.
On to the weather outlook for the "Super Perigee Full Moon" and the first day of the sun's passage over the equator.
TODAY: No change from yesterday under a near clear sky and coastal sea-breezes. Highs along A1A in the upper 70s, warming to the low to mid 80s away from either coast. Warmest NE and SW Florida.  A back door boundary ("cold front") is on the approach from the N-NE tonight.
TONIGHT: Looks to be clear or nearly so for moon viewing. Coastal lows in the low to mid 60s, warmest coastal SE Florida/Keys. Inland lows in the low/mid 50s...although there have been a few small pockets of upper 40s just about anywhere in the state the past few mornings. Could of fooled me, but they are occurring. Even in far South Florida.
SUNDAY: The March Equinox occurs at 7:21PM EDT, Sunday evening. But before that time, North through South Central Florida will herald in spring with of all things, a cold front? No fears.  The front will move into Central Florida sometime in the morning/early afternoon. It will initially pass through undetected to the casual observer, but will be followed a few hours later by stronger ENE winds of 15-25mph Sunday afternoon, as well as some clouds.  Model guidance is painting some light rain coverage over the East Coast of Florida, first to the North then spreading south toward Miami by late afternoon/early evening. However, due to the fact that we will remain atmospherically dry right up to and through frontal passage (at fire weather criteria in South Florida for instance), believe the moisture provoking 'rain' on the models will manifest as stratocumulus clouds. Sunday afternoon will be cooler everywhere by about 5 degrees, probably most notably inland though.  SW Florida will be the warmest tomorrow pre-frontal passage and furthest from the developing easterly flow (and likely without a cooling west coast sea breeze there).  Breezy all day Sunday beginning early afternoon through 8-9pm, with winds gradually relaxing overnight and becoming a faded memory by Monday. No significant changes to overnight low temperatures.

MONDAY-TUESDAY: Back to status quo as high pressure regains control and winds relax. Fire weather season conditions showing  true colors once again as we approach April...albeit, hopefully minus the fires. High pressure at the surface and aloft almost directly overhead with light overnight coastal land breezes, and afternoon sea breezes. Temperatures running like what you've felt the past few days already.

WEDNESDAY-THURSDAY: Minor weather change in store, mainly for the East side of the state.  We are entering another meteorological period influenced by a negative phase of the  NAO (North Atlantic Oscillation), this was the case for much of our cold weather periods this past winter...YES, we can say winter in the past tense by now. Feat not, it won't be getting real cold, at least not yet per guidance. Prior to the next frontal passage, the East Coast will likely lose the afternoon sea breeze effect, so high temperatures on these two afternoons (or maybe only one of them) will reach the low-mid 80Fs next week prior to frontal passage.
Front appears will pass through dry, but have low confidence at this point to declare this as fact. But rainfall of any noteworthiness declaration will be absent.  For now (as of this morning), will watch Wednesday/Thursday time frame though for  somewhere in North Central to South Florida, because I'm not quite ready to discount the possibility of a good shower or maybe a thunderstorm mid-late week (next week). Long time from now, but that chance looks pretty skimpy.

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