Record Warmth Expected Through Christmas Day as 'Blowtorch' Weather Pattern Develops in the East, Midwest

December 22,2015




 
Record-breaking warmth will grip much of the central and eastern states Christmas week, continuing what has already been a very mild month in those regions. Several cities in the East will likely see their warmest Christmas Eve or Christmas Day on record, adding to the more than 2,600 daily record high temperatures that have been tied or broken across the Lower 48 in the first 20 days of the month.
(MORE: 6 Incredible Facts About December's Warmth)
This mild forecast means the prospect for a white Christmas is highly unlikely for many east of the Rockies.
(MORE: White Christmas Forecast)
Meteorologists sometimes jokingly refer to the type of warm weather pattern we have seen recently, and the one this week, as a "blowtorch" in social media. The term may be a reference to weather maps showing temperatures compared to normal; these patterns tend to resemble a large red or white scorch mark surrounded by shades of orange and yellow, as if a giant blowtorch had been pointed at the Earth.
Of course, the actual cause is not a blowtorch but a weather pattern that keeps typical winter chill at bay and holds air from the Pacific or the tropics over the mainland United States.

Atmospheric Pattern Christmas Week

Below we have a look at the forecast, followed by perspective on how warm this December has been so far.

Christmas Week: Warm Weather Pattern Returns

Warmer-than-average temperatures have already returned to parts of the Midwest, South and East to start this week. On Tuesday, most locations from the Plains to the East Coast were experiencing temperatures 10 to 20 degrees or more above average.
(Forecast: Chicago | Boston | New York)
Though the intensity of the above-average warmth may fluctuate each day, parts of the central and especially the eastern states will see temperatures 10 to 30 degrees above average through the weekend and possibly early next week.

Forecast Highs Compared to Average

But this won't be a sunny, clear-sky type of mild weather pattern in many areas. A procession of low-pressure systems and a southerly flow of moisture from the Gulf of Mexico will bring periods of low clouds and rain, potentially leading to some travel hassles at airports and on the roads.
(FORECAST: Atlanta | Dallas | Nashville)
However, the cloud cover will also result in unbelievably balmy nighttime temperatures for Christmas carolers, partygoers and last-minute shoppers. Low temperatures could stay 15 to 35 degrees above average in some areas Wednesday through Christmas morning and beyond in parts of the Midwest, South and Northeast.
Dew point values will rise into the 50s and 60s for much of the East this week, which will make it feel more humid as well, and potentially fuel severe thunderstorm development.
Numerous cities will also flirt with daily record high temperatures through much of Christmas week, particularly Wednesday and beyond. This could be the warmest Christmas Eve or Christmas Day on record for several cities in the East.

Forecast Highs Christmas Week

Here are just a few of the daily record highs that are within reach this week Wednesday through Christmas Day:
Wednesday

• How many record highs possible? About 90 of the 236 possible weather observing sites in the Lower 48 will be within three degrees of a daily record high for Dec. 23.
• What states? This includes a swath of more than 20 states stretching from Texas and Florida to Michigan, New York and southern New England.
• Potential cities (current record in parentheses): Cleveland (61 degrees in 1933) | Buffalo (59 degrees in 1957) | Philadelphia (66 degrees in 1990) | Houston (80 degrees in 1990) | Orlando (85 degrees in 2011)

 Christmas Eve (Thursday):

• How many record highs possible? More than 90 of the 236 possible weather observing sites in the Lower 48 will be within three degrees of a daily record high for Dec. 24.
• What states? This includes more than 25 states stretching from Maine and Michigan southward to parts of the Gulf Coast states and Florida.
• Potential cities (current record in parentheses): Boston (61 degrees in 1996) | New York City (63 degrees in 1996) | Washington, D.C. (69 degrees in 1933) | Burlington, Vermont | (51 degrees in 1957) | Atlanta (72 degrees in 1984) | Raleigh (75 degrees in 1931) | Tampa (83 degrees in 2011) 
• Possible Monthly Record High: Philadelphia may break its all-time record high for December of 73 degrees. Burlington, Vermont, could flirt with its all-time December record high of 67 degrees.

A "cold" front will likely shave a few degrees off the warmth in the Northeast for Christmas Day, particularly across the interior.
That said, Christmas morning will be incredibly mild from the South into the Northeast. By the time children tear open their gifts, temperatures may be above normal daytime highs in many areas east of the Mississippi River.

Christmas Morning Forecast

It's possible that some cities along the immediate Northeast coast could set a daily record high for Christmas Day just after midnight or in the early morning hours thereafter. Daytime temperatures might be slightly cooler. This includes New York City where the daily record high of 64 degrees could be threatened in the very early morning hours before sunrise on Dec. 25, but will then see a daytime high in the low 60s.
Christmas Day (Friday):

• How many record highs possible? Just over 65 of the 236 possible weather observing sites in the Lower 48 will be within three degrees of a daily record high for Dec. 25.
• What states? This includes about 20 states stretching from the Northeast coast to Florida.
• Potential cities (current record in parentheses | * denotes record high may be in the morning hours): Atlanta (72 degrees in 1987) | Columbia, South Carolina (79 degrees in 1955) | New Orleans (79 degrees in 2008) | New York City* (64 degrees in 1982) | Providence, Rhode Island (63 degrees in 1964) | Tampa (83 degrees in 1984)

The map below shows our current forecast daytime high temperatures, along with the record Christmas Day highs, for selected cities.

Christmas Day Forecast Highs Compared to the Daily Record

For cities that are forecast to threaten daily record highs, this could be the warmest Christmas Day in your lifetime.
In fact, Christmas Day highs in parts of the Mid-Atlantic states and South may more closely resemble average highs around Halloween, than Christmas.
(MAPS: Monthly Average Highs & Lows)

Record Highs Set Christmas Week

A few record high temperatures were set to start the week.
On Monday, Dec. 21 the following record highs were set or tied: St. Louis (67 degrees tied); West Plains, Missouri (69 degrees); Springfield, Illinois (64 degrees); Peoria, Illinois (60 degrees tied); Naples, Florida (87 degrees tied).
The following daily record highs were set or tied on Tuesday: Nashville (70 degrees); Memphis (70 degrees tied).

December Record Warmth So Far

According to preliminary data from NOAA's National Centers for Environmental Information (NCEI), at least 2,646 record daily highs were tied or broken across the U.S. during the first 20 days of December, representing just more than 4 percent of the roughly 58,000 daily high-temperature reports received from more than 3,000 locations. An additional 3,728 record-warm daily low temperatures have been set during the same time period.
By comparison, just 146 daily record lows and 135 additional record cool highs were set in the same time frame.

Record Temperature Tracker

Incredibly, record daily high temperatures were set during the morning hours in several Midwest and Northeast cities during the four-day period spanning Dec. 12-15.

Why Will it Be So Warm Christmas Week?

A southward dip in the jet stream accompanied the brief cooldown that moved through the East this weekend. Now, early this week, the jet stream will quickly build back north across the eastern half of the nation and allow the widespread mild air to return. This lifting of the jet stream back to the north will be in response to a southward dip in the jet stream sweeping into the West.
Meanwhile, the clockwise flow around high pressure in the western Atlantic will allow southerly surface winds to dominate the East this week, pumping warm air from the tropics northward. Southerly winds ahead of a couple of low-pressure systems moving across the country this week will also help pump in the mild, moist air from the south.
Computer forecast models are still resolving the details regarding a shot of slightly cooler air Wednesday into Thursday in the nation's northern tier, specifically, how far south it reaches and how quickly it retreats by Christmas Day.
Either way, temperatures are unlikely to get much below freezing in most areas outside of the Upper Midwest east of the Mississippi River on Christmas Day, even in the morning and late evening.

MORE: Christmas Destinations