Heap Agriculture Service Info
Weather Features on the 1st
Day of Winter – December 21, 2010, 12:00 pm GMT
Ridge Persists over North Pacific Ocean
The large high pressure
system in the North Pacific Ocean is well supported by the cooler than
normal SST (Sea Surface Temperatures) that extend from the west coast of
North America to a line extending from the Hawaiian Islands to the
Aleutian Islands. This area
of cool SST anomalies is being supported by the PDO (Pacific Decadal
Oscillation) which remains in the cool phase at this time.
The Polar Jet runs up over this high pressure area into the
Bearing Sea and is driven south across the Gulf of Alaska to the
Northern California Coast by a trough located west of Vancouver Island.
This current track of the Polar Jet puts California on a
“precipitation bulls eye” similar to the one which occurred over the
western corn belt this past summer.
Tropical Jet to Remain Active
The Sub Tropical Jet runs
from east of the Hawaiian Islands to the northern Baja Peninsula, across
the Central Plains and into the Lower Mississippi Valley.
It weakens as it crosses the Plains and disappears over the
Appalachians. The large
high pressure centered over Mexico, just west of the Yucatan Peninsula, currently blocks most of the moister over
the south central and south eastern United States.
High Withdraws For Winter
Much warmer than normal
SST anomalies persist in The North Atlantic Ocean from Nova Scotia up
into the Labrador Sea and east across Iceland and the Norwegian Sea all
the way into the Barents Sea. The
unstable air created above these warm waters shifted the NOA (North
Atlantic Oscillation) into the negative phase in October where it
remains. The North Atlantic
Jet Stream continues to be very active,
with frequent low pressure systems moving across the North Atlantic.
The Azores-Bermuda High is faintly evident as it joins the arid
harmattan winds from Northern Africa.
This high pressure area, centered over the Cape Verde Islands
west of Senegal, encompasses the Inter-Tropical Convergence Zone (ITCZ)
Between Western Africa and Northeast Brazil.
Low Expanding and to Remain Active
The Arctic Low is currently split by a high pressure area
centered over western Baffin Island and ridge extending north across the
Pole to the Ural Mountains and south across western Russia. The large low pressure area east of this ridge encompasses
the entire Norwegian Sea, Scandinavia and the Baltic.
The Large low pressure area west of this ridge encompasses
Central Russia and Northern China. These large areas of arctic air continue to plague the
Northern Hemisphere with extreme cold over Europe, China and The United
States at frequent intervals.
La Nina Event Continues
A very large area of high
pressure persists in the South Pacific centered southeast of Tahiti.
This area is associated with the cooler than normal SST anomalies
that dominate the entire central and eastern Pacific Ocean.
These temperature anomalies are now near those levels reached
during the 1988 La Nina event. The trade winds remain stronger than average across the
central and western equatorial Pacific and the SOI (Southern Oscillation
Index) remains in the top 5% of historical values.
All leading international climate models suggest SST in the
tropical Pacific will remain at levels typical of a La Nina event
throughout the southern hemisphere summer.
The majority of models indicate this event will begin to weaken
as the central Pacific warms further into 2011.
Weather Features at the Winter Solstice
– December 21, 2010, 5:00 am CDT
For those interested in the surface winds at the winter solstice here are data for a few locations:
© 2011 Heap Agriculture Service, LLC