Saturday, November 17, 2007
Friday, November 16, 2007
Base Leg...Turning Final
Time series of SLP CLIMO...current wx...and 'preferred' MEI-analog Novembers.
First half of NOV 2007 SLPs mimic CLIMO/s low pressure signature over E-PAC. Both 'preferred' MEI-based 'La Nina' analog years are similar but they show a lower correlation with 2007...although '70 leans a bit more toward current conditions at end of period over E-PAC.
Current SLP time-series raises a measure of doubt about this year/s developing consensus for the "warm 'n dry" version of Nina-style winters.
Even stronger evidence of how useless analog forecasting can be...can be seen at 500 mb...
Early winter at least...lookin/ more-n-more normal as December approaches.
Thursday, November 15, 2007
Heresy in Harrisburg
"...colder than average and snowier than average..."
CBS-affiliate WHP-21/s wx heretic Tom Russell jumps into the winter forecast fray with both boots by taking the contrarian view.
His is the perennial favorite...'cold 'n snowy.' What/s not to like about that?
Bastardi Bold
"...(F)orecaster Joe Bastardi of AccuWeather on Tuesday reiterated his forecast for a warm winter in the Northeast, although the weather has been running colder than normal since Nov. 1. In an interview with MarketWatch, he said it will stay cold until the middle of December and then run about four degrees above normal in the northeastern U.S."
Rather BOLD prediction given December/s temperature departures during past -ENSO events. Much of NE has been one-half to one standard deviation below normal...the same being true for large portions of the M-A.
Monday, November 05, 2007
Nieves de La Nina
Take your pick.
D-J-F snowfall maps for seven La Nina Years Selected by Climate Predition Center using ocean criteria (1942-43...1950-51...1955-56...1970-71...1973-74...1975-76...1988-89)
Make your own.
Saturday, November 03, 2007
November/s ENSO Anomaly Forecast
Latest consensus ensemble mean forecast for ENSO Region 3.4 this MET winter (D-J-F) is ~-1.8°C...indicating 'strong' La Nina conditions are expected. Five of the six latest model runs are less than or equal to the forecast ensemble mean. Forecast values have delined each month since May (-0.6°C). Last month/s forecast was -1.6°C.
Monday, October 29, 2007
Winter '07 / '08 - Place Your Bets
Plenty-o-conventional wisdom underfoot this fall about a moderate-to-strong La Nina holding court over the upcoming winter. There/s even more CW obviously based on multi-event composites about how "warm 'n dry" it/s gonna be for the CONUS east of the much 'wetter' Lucky Ducks in OH / TN River valleys.
Too bad there/s no emoticon for skeptical chin-stroking with deep furrowed brow; otherwise...it might go here. Instead...take a look at the long-term composites for temperature and precipitation...
Temperature.................Precipitation
Mean temperature normal to 1°F above normal and mean precipitation '-2" to normal' extreme southern forecast area to 'normal to +2"' elsewhere.
The La Nina Analogs
The current MEI index 'trend match' has its best fit to '70 / '71...although the subsequent winter was almost over before the -ENSO event became strong. The latest numerical and statistical model output forecast a strong event (le -1.5°C) throughout all of met winter.
Note the highly ranked precipitation area (blue) across the GOM states and greater than median values along the EC and interior NE.
The next best MEI matches occurred prior to the non-Nina winters of '78 / 79 and '59 / '60. That leaves '88 / '89 as this winter/s runner-up MEI analog.
The '88 / '89 analog winter is closer to this year/s CW 'La Nina' winter forecast of 'warm and dry.'
Other Indices and MEI -- BFF or What?
PDO - '70 / '71 was 'warm' during its long-term 'cool' phase. This year/s PDO is 'cool' during a 'warm' phase. No benefits from these friends.
QBO...perhaps? The '70 QBO analog is ranked 5th; however...considering its 'E phase' in '70 / '71 flipped to W in March...two months earlier than the expected change in direction this winter. This flip/s timing could well be important this year b/c the QBO/s E phase is a leading indicator for a -AO and its associated increase in EC cold / storminess through the process of downward wave propagation.
AO...NAO...PNA...EP...and other like indices are thought to have skillful forecast ranges of about two weeks. There could be some utility in LR forecasting with these values if a multi-year trend is present.
The '70 / '71 analog demonstrates the variability of La Nina winters and suggests the coming winter won/t wind up 'warm and dry' in the NE or M-A.
Thursday, October 25, 2007
ECHAM/s Winter '07 / '08 Outlook - September
The German Climate Model...known as ECHAM...extended forecast for NHEMI sea-level deviations in hPa (1 hPa = 1 mb) are shown below. Not sure when it was initialized -- best guess is September -- or how often it/s updated.
October
Main feature is the strong suggestion of a +AO...which doesn/t appear to be born out by its observed index; however...some of its physical features (HIGH over N Pole; broad trof across E CONUS and the ATL Ocean) are roughly in the right places.
November
Strong omega block along the International Dateline...which teleconnects to a trof W - ridge E L/W pattern over CONUS. E of the block...storm track over Siberia would favor enhanced snow pack and development of Siberian HIGH. Trof along W CONUS has connection to HI Is. and the so-called 'Pineapple Express.'
December
Weak +PNA pattern with positive anomaly over AK and broad trof across lower 48. Rex block in the E ATL and negative anomaly INVOF Azores suggests the presence of a -NAO variant.
January
The positive anomaly over W CN suggests +PNA and the negative anomalies W of Greenland and INVOF the Azores favors -NAO...which implies cold and stormy conditions for E CONUS. Strength of positive anomaly over Netherlands could result from a high-latitude block.
February
Pressure anomaly couplet in N ATL Ocean points decidely to +NAO. ATL ridge axis extends W across CONUS suggesting 'mild' mid-winter temperatures in the E.
Saturday, October 20, 2007
First Snow Surprises Bulgaria
Closed LOW over the Bulgaria has dumped an early load of heavy snow on the region.
From Sofia News Agency...
"The first snowflakes for this winter season have started falling over Bulgaria's capital Sofia, the towns of Pernik and Dragoman on Saturday evening, surprising some and delighting others.
[...]
The thickness of the snow blanket in the mountains is expected to reach up to 70 centimetres (27")."
View Larger Map
The month of December is expected to be colder than last year with maximum temperatures between 3C and 8C.
Thursday, October 18, 2007
Cyclone Drones
Updated below
Developed and intended for investigating the lower levels of tropical systems...it/s not a stretch to imagine these 28-pound unmanned aircraft by Aerosonde being flown someday into extra-tropical winter cyclones deepening off the SE coast.
Aerosonde Gallery
Update
In 1998...an Aerosonde MK 3 crossed the Atlantic Ocean in 27 hours...using only 1.5 gallons of fuel.
Aerosonde specs
Wing span: 2.9 m (9.5 ft)
Weight:15 kg (32.2 lb)
Engine: 24 cc fuel injected
Payload(s): Up to 5.3 kg (11.5 lb)
Fuel capacity: Up to 6 liters (1.6 gal)
Operation: Autonomous
Generator: 75W
Navigation: GPS
Performance
Cruise airspeed:75-110 kph (40-60 kts)
Endurance: 5 - 30 hr(subject to payload)
Range: ~2000 km (50 kts)
Streaming video
Global iridium satellite
Service ceiling: 4500 m (15,000 ft)
Brochure (.pdf)
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