A MAJOR WINTER STORM CONTINUES ACROSS THE MIDWEST -- A potent winter storm system developed early Monday morning along a cold front over northeast Oklahoma and southwest Missouri. This storm system was accompanied by heavy snow, thundersnow, freezing rain and high winds. Through the day this storm system moved to the northeast, reaching northwest Ohio by late Monday evening. A warm front extended eastward across Ohio and New York State along the northern boundary of the warm and moist air to the southeast of the storm system. A cold front trailed southward and then southwestward from the low pressure center across the Ohio, Tennessee and lower Mississippi Valleys to the Texas Gulf Coast.
A band of heavy snow fell from Iowa eastward across northern Illinois and southern Wisconsin into southern Lower Michigan. This band of snow, with some snowfall totals exceeding 12 inches, was found on the north side of the storm track, in the region on the cold side of the advancing storm where the largest lifting of the moist air occurs. Some snowfall totals, especially in southeastern Wisconsin and northeastern Illinois were increased by lake-enhanced snow as northeasterly winds in advance of the approaching storm system traveled across Lake Michigan, picking up moisture. Thunder was heard along Chicago's Lakefront, indicating vigorous convection as the cold air moved across the relatively warm lake surface. Daily snowfall records were established at Grand Rapids, MI (14.2 inches), Milwaukee, WI (13.5 inches), Des Moines, IA (7.3 inches) and in Illinois, at Chicago-O'Hare (9.50 inches) and Peoria (6.6 inches). The Milwaukee and Grand Rapids records were also records for the month of December. Freezing rain fell for a while in the Detroit, MI metropolitan area as warm air was brought into the nearby storm system. A band of snow continued to fall as of late Monday night from southeastern Wisconsin across Lower Michigan, southern Ontario into western New York State. A variety of winter storm warnings and winter weather advisories continued along the storm track, extending from eastern Nebraska, across Iowa, northern Illinois, southeastern Wisconsin, northern Indiana, and much of Lower Michigan.
Strong winds also accompanied the storm system, which had intensified to a central pressure of approximately 992 mb during Monday evening. The tight pressure gradient to the west and northwest of the storm produced blizzard or near blizzard conditions in some areas near Chicago, as high winds reduced the visibility as the result of blowing snow. As of late Monday night, blizzard warnings remained in effect in the lakeshore counties of northeast Illinois and northwest Indiana. Winds reached at least 60 mph in northeast Ohio and near Pittsburgh, PA in thunderstorms along and ahead of the advancing cold front. For a while a high wind warning was in effect from northern Ohio eastward into Pennsylvania and New York State, then southward along the Appalachians to western North Carolina.
The storm system is expected to continue moving quickly to the northeast on Tuesday, reaching the St. Lawrence Valley near New York State's Thousand Islands by daybreak and to the Gulf of St. Lawrence by evening. Winter storm warnings and winter weather advisories were posted for the Saint Lawrence and Champlain Valleys of Upstate New York and Vermont, as well as portions of northern Maine. As the storm continues to move toward the East Coast, the winds along the coast are expected to increase in speed. Consequently, storm warnings for winds in excess of 54 mph were posted for the New England coast from Eastport, ME to Montauk Point, while gale warnings for winds between 39 and 54 mph extending southward along the coast from Montauk Point to Ocracoke Inlet, NC. Coastal flood warnings were posted for the Maine coast as high winds coupled with high astronomical tides from the recent full moon could flood low lying coastal areas.
A BLUE NORTHER -- Arctic air continued to expand southward across the Plains. This arctic air mass corresponds to a large high pressure system that stretched southward from southern Saskatchewan to the Red River Valley of north Texas. Afternoon temperatures were well below typical readings across much of the nation's midsection. This unseasonably cold air mass resulted in a record low temperature being set on Monday morning at Glasgow (19 degrees below zero), followed by an afternoon high temperature of 7 degrees below zero, which was a record low maximum temperature. Other record low highs were either tied or set across Nebraska, at Chadron (one degree above zero), Norfolk (2 degrees above), Omaha-Eppley (6 degrees) and Sidney (7 degrees).
Many places across the southern Plains, especially in Texas, experienced large temperature falls as the cold front pushed southward on Monday. Dallas-Ft. Worth had temperatures on Monday that were in the low 30s, well below the upper 60s of Sunday. By Monday night the cold front had moved out over the Gulf of Mexico. In the warm air south of the advancing cold front, Galveston, TX reached a record high temperature of 77 degrees.
By morning an area of rain, freezing rain and snow is expected to develop along the cold front over West Texas. A winter storm watch was in effect covering much of Texas and extending northeastward across portions of Louisiana, most of Arkansas into northern Mississippi and western Tennessee. Some Texas counties from near Del Rio on the Rio Grande to near San Antonio were under a winter storm warning.
UNSETTLED WEATHER ALONG THE WEST COAST -- A storm system was moving onshore along the Oregon and northern California coasts on Monday night. While the low pressure center was located within 300 miles of Cape Blanco, OR, an accompanying occluded front extended eastward into western Oregon and then turned into a cold front that extended southward across California. Snow was falling along the Coast Range of northwest Oregon and along the central Sierras of California. Snow advisories were in effect across central Oregon. Elsewhere, rain fell across central California.
This storm system is expected to spread precipitation across California into Nevada by Tuesday morning.
UPPER AIR -- The dominant feature on both the 500 and 300 mb charts for 00Z Tuesday continued to be the trough of lower heights over the nation's midsection. This trough at each level reflects the cold air found in the tropospheric column between the respective surfaces and the earth's surface. The arctic high pressure at the earth's surface is a relatively shallow surface feature as the ridge of high pressure quickly turns into a trough aloft. In addition, the winds moving around the southern periphery of the upper level trough, especially at 300 mb, are helping maintain the surface storm system over the Midwest. Winds reaching speeds of approximately 130 knots across the mid-Mississippi and Ohio Valleys produce a region of upper level divergence needed for intensification and maintenance of the surface low.
TEMPERATURE EXTREMES IN THE COTERMINOUS U.S. -- The lowest temperature on Monday was 27 degrees below zero at Flag Island, MN while Monday's highest temperature was 84 degrees at Corpus Christi and Kingsville, TX.
ALASKAN WEATHER -- A large and intense arctic high pressure system extended southeastward from the Arctic Ocean north of eastern Siberia to western Canada. Relatively cold air was funneled southward across the Panhandle. Farther to the southwest, a large and relatively intense storm system was moving northeastward across the western Aleutians. As a result of the tight pressure gradient between the high over northeast Alaska and the low to the southwest, a broad flow of southeasterly to southerly winds returned across western Alaska. The arctic stationary front stretched from the Kotzebue Sound southeastward to near Tok and the Alcan border. Significant precipitation was reported at Yakutat, Seward, Kodiak, Cold Bay, Valdez and Homer.
The lowest overnight temperature in the state as of Monday morning was 17 degrees below zero at Anaktuvuk Pass and Umiat. Monday's midafternoon highest temperature was 46 degrees at Homer, Port Heiden, Chignik and Sand Point.
HAWAIIAN WEATHER -- A cold front passed Kauai and had reached Oahu by late Monday afternoon, producing heavy showers and some embedded thunderstorms, especially west of Kauai. Some gusty winds were reported in the Kauai Channel as the front passed. Following frontal passage, winds on Kauai and Oahu shifted to north and by Tuesday the trade winds are expected to return as high pressure moves into the region. Winds on the other islands east of the front were from the south. The front should stall. High surf advisories were continued for the northwest facing shores of all islands.
From the files of the Aviation Weather Center, Kansas City, MO and Intellicast