Cold air is firmly entrenched across the northern tier of states. Early this New Year’s Day morning (Wed., Jan. 1, 2014), an east to west front from Oklahoma eastward through the Ohio Valley separated two disparate air masses. To the north (e. g., Iowa), temperature readings were in single digit and sub-zero territory with northeast winds; to the south (e.g., Oklahoma and Arkansas), temperatures were mostly in the lower 40’s) with winds blowing from the south (Fig. 1). The infrared (thermal IR) weather satellite image shows the region with the coldest air across Canada and areas near the U.S.-Canadian border (Fig. 2).
The IR satellite image and the companion water vapor image (Fig. 3) also confirmed the presence of an upper level disturbance (the elongated zone of cloudiness) moving across the Central Plains. This upper level feature is expected to foster the development of a weak surface low across the middle Mississippi River Valley later today and tonight. That system should track rapidly eastward, reaching the Appalachians by tomorrow (Thursday) morning.
That’s when a secondary low will begin developing along the Delmarva (Fig. 4). Such secondary lows often develop along the Atlantic Seaboard due to the proximity of cold air over land and warm air over the Gulf Stream offshore. This pattern of cold air to the west and warm temperatures to the south and east of a developing low-pressure system is the classic low-pressure evolution pattern.
By Friday, the original low-pressure system will have vanished. The circulation of the new low will dominate as it moves out into the Atlantic.
Given the strength of the approaching upper level system and the temperature distribution, the coastal storm is likely to intensify quickly. This will, in turn, create a strong pressure gradient between the developing low and the arctic high over the Mississippi River Valley. The result should be a very strong wind field, including wind gusts to 40 miles per hour or more over parts of the Northeast and possibly storm force winds over nearby ocean areas. Seas offshore are also expected to build to heights of up to 20 feet.
Forecasters are also looking for minor to locally moderate coastal flooding, mainly south of Boston, for the three high tides during the next two days. The Friday daytime high tide poses the most concern at this time.
Heavy snow is most likely to fall over southern New England and northern parts of the mid-Atlantic. With more than a foot of snow forecast along the I-90 corridor (Buffalo to Boston), look for wind whipped snowdrifts to build to three feet or more especially closer to the Massachusetts shoreline. Don’t rule out local blizzard and associated “white-out” conditions.
The upper level “Hudson Bay” low will remain, albeit with a few oscillations, firmly entrenched over east-central Canada for the next two weeks (Fig. 5 and Fig. 6). This means that a series of Alberta Clippers will again travel southeastward from the Canadian prairies to the Great Lakes or middle Mississippi River Valley before turning eastward. Depending upon the amount of cold air in place, periodic snow episodes (or cold rain events) will punctuate the weather from Missouri eastward.
Some of the cold air masses may make it southward to the Gulf Coast or even the Florida peninsula. Any cold air that reaches Florida will have its one or two morning presence quickly replaced by milder air from the Atlantic Ocean. This will be linked to a wind shift from northerly to easterly as the high-pressure system to the north changes its location. One such invasion is anticipated for Thursday afternoon into Saturday morning. Early morning freezing temperatures for this event should be constrained to far north Florida.
From the front range of the Rockies westward, rain and snow will be very limited for the next two weeks thanks to an upper level ridge. That means that dry conditions across the region will only deteriorate further. Currently about 31 percent of the area is under severe to exceptional drought (Fig. 7).
© 2014 H. Michael Mogil