"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 22, 2012

Small Rain Chance Increasing Clouds Late Today NorthCentral

300 millibar (mb) depiction from the GFS Forecast Model for 7pm this evening
Upper level low well south of California at time appears to be drifting south; this will move east later this weak as the model shows is a bit debatable, at least in regard to how much effect it will have on Florida's early weekend weather.  Otherwise,  annotated in green is where I am thinking some light rain could fall after dark toward mid-evening. Thunder 'possible' toward the Gulf Coast.

TODAY: Little to no change from the previous post of Tuesday (other than the questionable rain chance). Mid-level trough passing north of the state today from west to east with SW surface winds here around 10-15mph some locations. Warmer along the SE Florida coast, but increasing clouds further north toward Central FL should limit daytime highs to a small factor. Otherwise, satellite imagery and lightning data show a cluster of thunderstorms well out in the Gulf which appears to be heading toward the Cedar Key zone by very late afternoon. High clouds should precede this activity. Whether it holds together to the landmass after crossing the Loop Current and surrounding warmer waters is debatable, although, I'm inclined to reason that regardless, some "elevated type activity" (not surface based) could occur as shown in this depiction. At the hour, the Storm Prediction Center (the official forecasters) are out-looking the Panhandle for potentially strong storms under a "See Text" graphic,  but not indicated here in this un-0fficial blog.

Lightning is occurring in the orange box. This area appears to be spreading almost due east, thus the land areas are shown in orange for possible lightning. If this activity is indeed merely elevated 'junk-vection' it could pass entirely across the upper peninsula seeing as how it would not be contingent upon an unstable lower level atmosphere to sustain itself. There appears to be a mid and/or upper level vorticity maximum (albeit weak) that is working this activity, so perhaps that is the only 'requirement' for today's activity to manifest. This vorticity maximum (vort max) is expected to cross the state near Ocala toward Gainesville after dark but before midnight...

THURSDAY/FRIDAY NIGHT: Other than today's system of 'sorts', a prolific subtropical jet (see first image) is in place across the southern tier of states in a developing zonal flow of quick moving spurts of energy. Wind each day from the SW-WSW and warmer on Thursday and Friday (especially), when cloud coverage might be less extensive over much of the peninsula. Highs in the mid-upper 70Fs and some near 80F+ south today, but more so over a broader expanse Thursday and Friday. Might see some near records highs on Friday South Half of state as the next front moves in. Front enters Central after dark Friday.

SATURDAY/SUNDAY: Front is expected to stretch on in from the N-NNW-NW after dark Friday evening preceded by increasing clouds once again and a small to fractional rain chance through midnight before stretching thin and beyond its mean. Do note, that any rain from this boundary appears will be BEHIND the front rather than ahead and along it. This front will be associated with the low pressure system now well south of California noted in the first image above with movement indicated by the arrow in red which will follow a due course similar to the current winds also shown (in yellow). 

With increased clouds and some 'warm air over running' in place behind the cool and shallow air mass, Saturday could be a bit cloudy and cool as winds shift from NNW-NNE during the course of the day while winds just 5000 ft and above remaining from the west. Hence, this will be a 'shallow front' (not extend far up into the atmosphere)..and not long to last. In fact, by Sunday the wind will already be back from the east by day's end.

BEYOND: Next front is forecast to enter the picture in 3-4 days along the zonal flow pattern toward Tuesday/Wednesday . The trend has been for some time to indicate that the jet stream as shown in the first image will be lifting even further north, making for weak fro-pas (frontal passages), but perhaps prolonged periods of clouds as they struggle to squiggle clean of the area, leaving residual atmospheric moisture as their calling and goodbye cards.

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