Barry:
I want to get this to bobby berra also. I am looking for a return to a colder than normal winter. Especially the mid atlantic and northeast. Please look at this forecast. This is a summary of the LAST La Nina cycle we had and this one should repeat. If what I am believing comes about, oil prices will will rocket upward, and my Fidelity and Vanguard energy funds are only a phonecall away.
The key to this whole report is in the storm tracks that will hit us in the fall. They will repeat in the winter. So watch the storm tracks that we have when hurricane season hits us; this will set up this winter.********************************************************
Hope you enjoy the reading.
LA NINA winters show a tendency for a southwestern US trough and southeastern US flat ridge. Cold air tends to accumulate in western Canada and spill into the central states and then move quickly across the northeast and southern Canada. Colder than normal temperatures are observed in the north central states. The area near the eastern Gulf and Florida would be drier than normal and warmer than normal with this pattern. In between, an active storm track operates, producing frequent snows from the southern and Central Rockies northeastward across the Central Plains, the Great Lakes to northern New England. Heavy rains would typically occur just south of this snow area.
Last year this pattern periodically established itself. Record cold temperatures and heavy snows recall were experienced across parts of the midwest. However, there was another twist to the pattern last year as unusually persistent and strong high latitude blocks forced cold air to periodically bulge much further south and east to the mid-Atlantic and even southeast coast.
This year, the various computer models used by the Climate Prediction Center of the NWS to predict how these oceans temperatures will change, show conflicting indications. One model shows the cool phase giving way to a warm phase by the end of the winter. Some show the cool phase remaining till the spring. Should the water stay cooler than normal, we might see this pattern at least at times. If the water should warm quickly to above normal, the southeast could turn cool and wet while the northwest and north central warm to above normal. Given the weakening of the current LA NINA and the uncertain forecast, the Climate Prediction Center is treating this factor as neutral this winter.
SEASONAL/YEARLY LAG CORRELATIONS
These statistical models use historical pattern relationships season to season and year to year to determine probability of above or below normal temperatures and precipitation for upcoming seasons. There was no strong signal given for this winter as the probabilities have ranged from slightly favoring milder than normal conditions to inconclusive.
NORTH ATLANTIC OSCILLATION - GREENLAND BLOCKSLike the Tropical Pacific, the pressure patterns in the North Atlantic shows a tendency to oscillate. It too is bi-polar but the two pressure centers are situated north- south instead of east-west as in the Tropical Pacific. The normal mode has a strong cold low near Iceland with a tendency for a strong warm ridge well to the south west of the Azores. When the North Atlantic Oscillation is in this phase, cold air is drained quickly off the east coast often leading to a mild winter in the states.
Periodically the opposite pattern develops. A large pool of relatively warm high pressure at high levels build well to the north usually first over Scandinavia then retrogresses (backs up) west to the vicinity of Greenland then maybe even eastern Canada. These large ridges act like rocks in a stream to block the passage of storms. In the Atlantic these storms tend to be deflected unusually far south where they migrate east to the Mediterranean. When these blocking ridges develop in the North Atlantic, cold air tends to accumulate (pool) over North America and eventually spread south to encompass most of the eastern two-thirds of the nation. Storms move along the edge of these large cold highs and bring heavy snows.
Last winter this blocking pattern was more persistent than in any year in the last century. This is what led to the record snows. This blocking has been observed to occur with a higher frequency near the quiet phase of the 11 year solar (sunspot) cycle. 85% of all blocks that have predominated for at least one month in the last century have occurred near the solar minimum. We are near the solar minimum. It the last three cycles, blocks occurred in two successive years near the minimum. In the late 70s, these blocks repeated in three successive winters. Those winters ranked among the coldest and snowiest this century.
Blocking continued to show itself this summer and fall in high latitudes. But this fall it was found over the northern parts of Canada. In the northern Canada position, the block results in expanding polar air masses which descend slowly (often in pieces) into the lower 48 states. The jet stream also is depressed to the south of normal across the states. Temperatures across much of the nation in these situations average below normal although the air is often not as bitter as when the blocks are found further west (Yukon or eastern Alaska) or further west (Greenland).
In the fast upper level flow along the edge of the cold air masses, the storms tend to be frequent. They tend to start out strong on the west coast, weaken as they move rapidly across the states producing bands of light to moderate snows. This would mean snows for the Pacific Northwest, the western mountains, lots of lake effect snows and then snows for the easternmost areas like Cape Cod and the Islands. When the storms reach the east coast they can again explosively deepen as they pick up Atlantic moisture. If the blocks develop in north central Canada, cold troughs will tend to pool near the Canadian Maritimes which favors most of the storms staying far enough off the coast to miss the major cities. If the blocks instead position themselves further east, the eastern cities and the Appalachians would again be under the gun.
FALL STORMS TELEGRAPHING WINTER STORMSIt has been shown in research at the University of Virginia that storms tracks persist well from season to season, especially fall to winter. Many years, the storms tracks you observe in the fall, repeat from time to time in the winter.
The strong winds and heavy rains in the west in mid-November was not really associated with major Pacific storms but with the strong gradients of temperature and pressure at the leading edge of the cold polar air mass pressing down from Canada. Moist tropical air did feed into a few of the systems (the Pineapple Express) helping to make the rains particularly heavy. Many waves of low pressure have scooted along this boundary and eventually intensified when the reached the Atlantic but mostly out at sea.
Late in November a series of Pacific storms on a more southerly track brought some heavy snows to the western mountains and heavy rains to parts of the southern plains. These storms then headed towards the Great lakes. This is a La Nina storm track. If it is a track we see repeated often it would mean great skiing in the west and no repeat of the Great Plains drought of last winter.
Most of the east coast storms have moved out to sea though we had at least one early season coastal storm that would be a monster snowstorm in the winter months.
VOLCANIC ASH
Major volcanic eruptions that spread debris into the high stratosphere have been shown to lead to cooling of the average earth temperature. The super eruption of Pinatubo is blamed for the unusually cold winter and summer a few years back. There are a few volcanoes in the news this year, the most recent in Alaska but the total mass of dust and debris produced is small compared to Pinatubo. This is not believed to be a significant factor this year.
SUMMARY
So LA NINA comes out weakly on the side of a cold winter in the northwest and northcentral and a milder winter in parts of the east and south while the above normal high latitude blocking potential in another year of a quiet sun favors another cold and snowy winter for the central and east. Storm tracks this fall were consistent with these two factors. We may see an oscillation between the two regimes (much as we did last winter. So as a result here goes the forecast.
Periods of stormy, wet and windy weather for the west will result in temperatures averaging to below normal and precipitation near to above normal . The mountains of the west will do well with a very good snowpack. When the storm track is across the north the northern mountains will get heavy snows. When it drops south, the southern areas will benefit.
The plains will see no repeat of the serious winter drought of last year. When the northern storm track is the active one, the northern plains will see frequent light to moderate snows and southern areas will be dry as air dries out coming downslope from the mountains on westerly winds. When the active storm track is to the south, the central and even southern plains will see good rains and snows. On average temperatures should average near to below normal across the north central and near to above normal in the southern areas. Precipitation should be near to above normal
East of the Mississippi, we see a winter with spells of very cold weather and maybe a troublesome snowstorm or two but not a repeat of the record snows of last winter. Cold air outbreaks could be fairly frequent and lengthy if the some of the early season outbreaks are omens of things to come. If massive outbreaks occur, heavy snows can fall along the edges in places that rarely see heavy snows like along the Gulf coast and the coastal Carolinas. The cold likely will not be continuous.
When the blocks break down and the flow becomes more zonal, the pattern will probably revert to the LA NINA favored pattern of central and western United States troughiness and southeastern ridging which will bring mild spells to the southeast and thaws to the areas further north. When these patterns occur, bands of moderate to heavy snow could fall from the southwest across the central and parts of the northern Plains to the upper midwest. The relative percentage of time this pattern occurs relative to the more amplified cold pattern will determine whether temperatures average below normal for the winter as a whole.
The best guess is that temperatures will average below normal in the Great Lakes and a bit above normal in the Gulf states. Precipitation will be above normal in the lee of the lakes but near or below normal elsewhere. Florida should enjoy their dry season and earn their reputation as the sunshine state.
Along the east coast, there will be some spells of very cold weather but they will be followed by thaws with some rain maybe beginning as ice or snow as storms move up through the Great Lakes and southern Canada. Trailing storms behind these systems may bring moderate snows. When the cold troughs come to the east, ocean storms will likely develop but most will stay far enough offshore to miss most of the major cities. Cape Cod and the Islands could catch some of that snow. If and when blocking finds its way to eastern Canada or the North Atlantic at some point, snow storms will threaten as they did last winter. If a repeat of the big October storm were to occur, they will measure the snow in feet and not inches. The best guess is that the temperatures will average below normal in the northeast and mid-Atlantic and near to a bit above over Florida. Precipitation and snowfall will average a bit above normal from the mid-Atlantic northward, near to below normal in Florida.
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