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| Current Snow Cover in the Northern Hemisphere |
Various forecasts are now coming out for the winter. Many of these projections are banking on the idea that a
"weak" El Nino signal will develop in the Pacific; this climatic shift would help to enhance the southern jet stream, making for plenty of opportunities for wintry weather across much of the nation.
There are many factors in seasonal forecasting as we know, but one that is critical in determining our weather pattern over the winter involves the El Nino state in the Pacific, especially in the critical region of 3.4.
A warming signal there very often leads to snowy winters in the eastern states (or at least near-normal snowfall).
The various models are picking up on the warming in the central Pacific.
By itself, the presence, of lack thereof, of El Nino doesn't always tell us much:
However, seemingly dry periods can turn on a dime once the conditions become favorable for a "weak" El Nino to take hold leading into the winter months. In fact, some of the closest matches found here using
NOAA climate data suggest that the dryness of the fall can be wiped out in a hurry once the El Nino state asserts itself, which it should over the next six weeks.
CENTRAL PARK'S PRECIP FROM JULY THROUGH OCTOBER 2013:
JULY- 2.89 (-1.76 BELOW NORMAL)
AUG-2.85 (-1.59 BELOW NORMAL)
SEPT- 2.95 (-1.33 BELOW NORMAL)
OCT- 0.36 (-4.04 BELOW NORMAL)
TEST CASES: YEARS WHERE WEAK EL NINO DEVELOPED (FROM A NEUTRAL STATE) WITH DRY SUMMER AND FALL SINCE 1950 AT CENTRAL PARK
1966-precip Jul-Dec
JULY: 1.25
AUG 1.89
SEPT: 8.82
OCT 4.64
NOV: 3.47
DEC: 3.18
WINTER SNOWFALL 1966-67: 51.5" OF SNOW
1968-Precip Jul-Dec
JULY: 2.63
AUG: 2.88
SEPT: 1.97
OCT: 2.20
NOV: 5.75
DEC: 4.15
WINTER SNOWFALL 1968-69: 30.2" OF SNOW
2001: Precip Jul-Dec
JULY: 2.04
AUG: 2.56
SEPT: 5.31
OCT: 0.66
NOV: 1.36
DEC: 2.27
WINTER SNOWFALL 2001-2002: 3.5" OF SNOWFALL
Our closest overall matches were probably 1957-58 and 1965-66, which show up twice. They are also both years where conditions in the critical El Nino 3.4 region were heading towards warmer.
Accuweather Winter Forecast 2013-14
Weatherbell Winter Forecast 2013-14
The bottom line: With any sort of
significant blocking in the north Atlantic in the form of high pressure building down, a southern jet stream should develop from the emerging "weak' state of El Nino in the Pacific, which should lead to an active winter around these parts, especially January through a good chunk of March. Even with the Pacific looking favorable for snow, a lack of blocking would lead to below normal snowfall, since cold air would not be as available to tap for the coastal locations.
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Weather.com: What is "blocking?"
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