Strong Polar Front Pushes Into Gulf Of Mexico

A powerful clipper moving through the Great Lakes has pushed a cold front off the east coast, through central Florida, across the northern Gulf of Mexico and extreme south Texas.
Dewpoints are in the 40s along the Gulf Coast - and even 42 at Tallahassee:
A rare September severe thunderstorm/tornado outbreak is expected in the Central Plains tomorrow:A limiting factor however, may be the rather limited moisture that was left behind after such a strong polar intrusion. Dewpoints across Oklahoma and north Texas are mostly in the 30s and 40s:With 60+ dewpoints confined to southern Texas, it will be difficult for thunderstorms to develop in Kansas tomorrow until after dark. It will just take that long for the good moisture to get there - even on the 40 knot low level jet that is forecast by 12z.

Great Lakes Storm Bottoms Out At 982 MB

Storm at peak strength this morning:

Powerful Cold Front Hits Midwest Today

A strong clipper system at 991 millibars near International Falls is forecast to move southeastward over the Great Lakes today, deepening over Lake Huron tommorow to 978 mb according to some models. Wind gusts may be as high as 50 mph in the vicinity of such a storm and higher in any thunderstorms that are able to form along the relatively moisture starved cold front. Along with the high winds will be a sharp temperature drop - perhaps 10 degrees in just few hours. Parts of the Upper Midwest, Great Lakes and New England will for the first time this fall have highs only in the 50s over the next several days.

Update: Cold Targets Northeast

A few stations have already been below freezing across the northeast over the past three days - mostly in northern Maine on Thursday morning. Tonight could be the first widespread freeze for New England with clear skies, light winds and dewpoints mostly in the 30s. Models are in pretty good agreement on a much stronger cold wave next weekend, possibly penetrating down into the Mid-Atlantic region as well.

Early Freeze Likely For Midwest Next Week

GFS continues to insist on a major cold punch for the Midwest by the middle of next week. Ensemble and European models are now increasingly supporting this idea. The GFS was at first an outlier with the upper trough which cutoff over the Northern Plains last week. But it correctly predicted the very unusual retrograde and northward track that it had all the up to northern Saskatchewan. It will be interesting to see if the GFS will get it right again. The 12z run even raises the possibility of snow in Minnesota on the 24th as 850 temps drop to -8C.

How Strong is This El Nino?

According to the Climate Prediction Center, El Nino is expected to strengthen and persist throughout the winter of 2009-2010. Recent sea surface temperature anomalies in the tropical Pacific would seem to support this:
As would the equatorial subsurface temperature anomalies:A broader look at subsurface temperatures (not just equatorial) however, shows a different story:This pattern is consistent with the cold phase of the Pacific Decadal Oscillation (PDO). When the PDO is cold, El Ninos tend to be weaker and shorter. The area of warm water at depth is seen to be only in a very narrow band right along the equator. This band becomes even narrower when looking at the anomalous depth of the 20C isotherm:It seems unlikely that this El Nino will strengthen especially given the near normal trade winds:
Because stronger than normal trade winds have generally prevailed since late 2006, warm water piled up in the western Pacific. The westerly equatorial counter current is what compensates for this effect. I suspect that much of the warm water in the eastern Pacific is due to an enhanced equatorial counter current:As Joe D'Aleo has pointed out, the warming of the Pacific is following a similar path to last year. La Nina returned and a cold and snowy winter for the Midwest and northeast followed. Even if this El Nino maintains itself through the winter, it is difficult too see how such a narrow band of deep warmth could have a strong impact. This along with a very quiet sun should give us another cold winter.

data from:
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/enso.shtml
http://www.cpc.noaa.gov/products/GODAS/
http://www.oscar.noaa.gov/datadisplay/