Friday, 2015:
I'll summarize the weather pattern for the first half of November with
the Yogi Berra quote: “It's like déjà vu all over again.”
The first half of November will bring a continuation—though less
extreme version—of the mild, dry pattern of recent weeks. A
temperature rollercoaster ride of sorts will develop as shallow shots
of Canadian air bring a couple cool days followed by a few days of
much warmer conditions as southwesterly flow develops. The opening
days of November will exemplify this pattern as mild temperatures (low
70s) on November 2 – 3 give way to seasonably cool highs (~60°) on
November 4 – 6.
The second week of November will bring more of the same, although
temperatures will be a bit less variable with highs mainly in the 60s
(normal is mid/upper 50s). With dry West and Northwest flow dominating
the pattern through November 12th, I see almost little chance for
significant rainfall before mid-month. Therefore, the first half of
November will follow October’s lead with temperatures averaging 3 or 4
degrees above normal, while precipitation is below-average…or even
nonexistent.
So when will the stubborn pattern of recent weeks give way to a
colder, more disturbed configuration more typical of November? I do
see some subtle signs in the hemispheric pattern that high-latitude
ridging and retrogression of the mid-latitude longwave troughs might
lead to notable changes during the final week or two of November.
While I’ll stop short of forecasting a shift into an early-winter-like
pattern, I do expect the final 10 – 14 days of November to bring a
couple sharper blasts of Canadian air and likely some snow showers to
the mountains of PA. If the mid-latitude pattern fails to retrograde,
however, then fast jet stream flow off the Pacific will continue to
push mild air masses from the Plains to the East coast. Thus, despite
a couple late-month brushes of much colder air (and perhaps flurries)
it may be December until we click into a wintry pattern that could
bring the season’s first measurable snowfall.
