(NA) NA July 2012 Weather Discussion/Reports
Posted 07 July 2012 - 01:15
Well as the El Nino begins building in the western equatorial region of the N. Pacific; in the central region of the N. Pacific a High Pressure continues to heat up. This abnormal High Pressure, void of moisture, appears to be winding up in the N. Pacific and pumping the compressed warmer wind across the SW US. It continues to stoke the wildfires and dump excessive warmth from Wyoming-Colarado to the coast of NY and down to Georgia and back. With low humidity coupled with winds and heat, this outflow is blowing across the area like a blow torch in Hades... In the meantime, riding the leading edge of the High Pressure wave over Georgia are large squall like storms over the N. Florida panhandle area.
While through all of this it seems our friends to the NW region of NA are apparently enjoying a break from the heat of prior years. At the same time we see that Greenland (Vineland) begins to green again... At least, if nothing else, our friends in the Caribbean and Central American region seem to be enjoying a near normal Summer so far.
Posted 11 July 2012 - 14:36
A interesting turn of events appear to be looming. The recent heatwave which was reported to have broken 2460 previous daily Tmax records seems to be sliding away. At the same time off the US west coast over the SE N.Pacific the dominat dry zone associated with a coastal HP appears to be breaking down.
The upper level winds which had reached from S. Cali to Up-State NY have switched up a bit with the Sub-Tropical Jet lifting to near the Idaho/Montana border then dipping across the central US to dart back up the Atlantic coast, merging with the Polar Jet over Maine, before rocketing towards the SW corner of Greenland.
The resulting flow has increased a mid-level cloud band stretching from OK through Va and the Carolinas. Along this occluded front pulses of upper level lows appear to be offering enough instability to replenish much of the moisture drawn out by the near two week heatwave.
At the sametime over Canada the cooler air comming down from the Arctic region over the Yukon region appears to be slackening in the GFS model at 24hrs out. I suspect as the added warmth of both jet stream bands move off East, the warm, moist air over Alberta may become more normal, only time will tell...
Whether the AO will continue to demonstrate a near "split personality" or not depends on if the seasonal Equatorial/ITCZ flows are re-established..., and the Med-African heatwave begins to breakdown. I suspect based on watching the METEOSAT IR image, there appears to be an expansion of wv/convective pulses moving over the "Horn".
Whether an increase in African ITCZ convection leads to developing TSs in the Caribbean or western Atlantic depends on the shear conditions over the Southern or 20N region of the N. Atlantic. (The "Horse Latitudes" it has not been of late..., most of the normal 30-35N flow has dropped down to between 25-30N as it approaches the West African coast.)