1:00pm Thursday, October 23:
A large upper-level low pressure system will slowly exit to our east
today and tonight, thus allowing for a return of sunshine on Friday.
Looking ahead, the pattern looks very un-winter-like as Arctic air is
locked away far to the north for the foreseeable future. Instead, mild
flow from the Pacific will dominate in the mean, and so I expect
October will conclude about 2 degrees above normal.
What about the weekend? After a partly to mostly sunny and mild
Friday (mid to upper 60s), a shallow cold front will cross the
Commonwealth late Saturday. A mild west wind will blow Saturday with
highs again in the mid to upper 60s (a few degrees above normal).
Afternoon and evening clouds may drop a sprinkle, but little more.
Sunday will then turn windy and a bit cooler (seasonable highs in the
low 60s) and Sunday night may bring a touch of frost in a few cool
spots (lows in the mid to upper 30s). Otherwise, westerly flow will
bring a spell of Indian Summer Monday through Wednesday with highs
likely reaching the low to mid 70s on one or two days--best chances
are Tuesday and Wednesday, before a weak cold front moves through
Wednesday late afternoon or evening with clouds and a shower.
Looking towards Halloween and beyond...I see a couple more glancing
cold fronts that will bring brief cool downs (around October 30 and
again around November 1st or 2nd...which might yields a few snow
flakes in the higher mountains of the Northeast). Still, the large
scale pattern favors mild conditions east of the Rockies into the
first week of November, so at worst the warm and cold days (here in
LanCo) will be roughly equal in magnitude making for a near-average
first week of November.
10:00am Monday, October 20:
Despite the season's first widespread frost this morning, we continue
in a relatively mild pattern; and it looks likely that October will
conclude as the warmest month of 2014 relative to average. Through
October 19th, the month-to-date
departure from normal is about +1.5 degrees. The month's final 12
days look to continue this trend, so that October should conclude 1.5
to 2.0 degrees above normal.
Short-term, we have a clipper system digging in tonight and Tuesday
with scattered showers developing. If this was an ordinary clipper it
would exit quickly and dry conditions would arrive for Wednesday.
Unfortunately, this is a rare clipper that will sharpen up and "close
off" as it reaches the East coast--the result will be a large,
slow-moving upper-level low that will take two or three days to clear
the coast. Right now, an extended period of steady rain looks most
likely from NJ and the Poconos up through eastern New England, while
persistent clouds and scattered showers dominate the eastern half of
PA. So while I don't expect a washout here, a shift in the location of
this upper-level low will affect the midweek forecast. My current
position is that a few showers are possible Tuesday and the best
chance for scattered showers or a few hours of steadier rain is
Tuesday evening through Wednesday night. Conditions should gradually
improve Thursday, though a lingering shower is certainly still possible.
Assuming this upper-level system exits on schedule, the period
Friday through Sunday looks pretty good with a seasonable high
pressure taking control. A backdoor cold front may attempt to drop in
early next week with a shallow push of Canadian air. Otherwise, I
expect a warming trend next week--highs possibly returning to near 70
degrees--as westerly flow prevails across much of the country.