STORMY WEATHER OVER THE NATION'S CENTER --Snow, heavy rains, large hail, high winds, and tornadoes were found across the central portions of the country on Wednesday as part of two separate storm systems.
One of the systems consisted of a set of lows, with the dominant low pressure system located in southern Arkansas late Wednesday night. This low had formed as the primary low, located to the northwest in eastern Oklahoma had undergone the occlusion process. A warm front extended east from the low in Arkansas toward central Alabama, and a cold front traveled southward through the Lower Mississippi Valley, before curving westward along the Gulf Coast. This system moved out of the southern Rockies late Tuesday and crossed the southern Plains following the Red River Valley. Late Tuesday night severe thunderstorms near Midland in west Texas produced hail, wind gusts exceeding 70 mph and at least one tornado. On Wednesday morning a tornado struck and caused damage to a shopping center in Conroe, TX north of Houston. High winds caused damage in the Dallas-Fort Worth area from thunderstorms ahead of the cold front. Tornadoes were also reported from Arkansas and Mississippi, where large hail fell.
On the south side of the low, warm moist Gulf air was carried northward into the storm system on southerly winds. Record high temperatures were set Wednesday in Texas at Corpus Christi (92 degrees) and Galveston (82 degrees). As of late Wednesday night, numerous thunderstorms, some with unconfirmed tornadoes, remained across Mississippi and Alabama. Several tornado watches were in effect across Mississippi, Arkansas and Louisiana, to extend into early Thursday morning.
To the north of the low, heavy rains fell over a wide area of stretching from Kansas to Tennessee. By late afternoon, daily precipitation records had been exceeded at Springfield, MO with 2.49 inches, at in Nebraska, at Grand Island with 1.78 inches and at Hastings (1.56 inches). Flood watches remain in effect for parts of southeastern Kansas, eastern Oklahoma, Missouri, Arkansas and southern Illinois.
A second storm system affecting the Central Plains was located in northern Manitoba, with a trailing cold front that crossed western Lake Superior and continued in a south-southwest direction to west Texas. In the cold air to the west of this storm, rain changed to snow over the high Plains of eastern Colorado and western Nebraska. An inch of snow fell in Denver, CO. Much of the snow could be attributed to the upslope travel of the air as it moved toward the west. Winds gusting to more than 50 mph were also reported in Nebraska. Afternoon high temperatures on Wednesday across the central Rockies were nearly 20 degrees below the average high temperature for this time of year.
By Thursday morning the dominant low pressure system from Arkansas is forecast to move northeastward to just south of Saint Louis, MO. A warm front should extend to the southeast toward central Georgia and the cold front should run southward to just east of the Mississippi Delta. The cold front trailing the Canadian low is expect to stall over the upper Mississippi Valley and eventually weaken. A broad area of precipitation is anticipated to stretch from the Appalachians west to the Plains and from the Tennessee Valley north to the Great Lakes. Most of the precipitation should be in the form of rain, while in the colder air, snow could fall over eastern Kansas and western potions of Iowa and Minnesota. A slight risk of severe thunderstorms remains across the lower Mississippi Valley until Thursday morning, with the area shifting toward the northeast into the Ohio Valley and Carolinas later in the day.
QUIET IN THE WEST -- A large ridge of high pressure remained over central British Columbia and kept the weather over a large section of the nation to the west of the Rockies relatively tranquil. The dry air mass, light winds and cloud-free skies allowed for strong overnight radiative cooling. Record low temperatures were either tied or set on Wednesday morning in Oregon at Meacham (18 degrees), Pendleton (27 degrees) and The Dalles (30 degrees), and in Washington State at Yakima (24 degrees) and Walla Walla (31 degrees). However, daytime temperatures have warmed toward seasonal averages. A slight intensification and a southeastward shift in the high is anticipated on Thursday.
FIRES CONTINUE ACROSS THE SOUTHEAST -- The lack of rain, coupled with the warm weather and the dry gusty winds has increased the fire danger over Florida, southern Georgia and southeast Alabama. Other states, to include Tennessee and North Carolina also experienced wildfires. More than 200 forest fires were reported in Georgia on the first two days of the week. More than 600 acres of Okefenokee National Wildlife Refuge had burned. In Florida, the governor declared a state of emergency, as at least two homes were destroyed. The anticipated precipitation is welcome, but it will not be sufficient to end the drought and lightning strikes could ignite additional fires.
UPPER AIR -- The major features in the mid- and upper-tropospheric wind flow as depicted on the 00Z Thursday 500 and 300 mb charts indicate more north-south excursions to form a more meridional pattern than earlier. Winds enter the country on the north side of a ridge along the West Coast where northwesterly winds then travel toward the southeast to curve around the south side of a trough over the Rockies. To the east of the trough, the winds travel toward the northeast passing around a ridge over the Great Lakes and then finally turn toward the southeast as a trough is located along the East Coast.
YESTERDAY'S TEMPERATURE EXTREMES ACROSS THE LOWER 48 -- The lowest temperature on Wednesday was 16 degrees at McCall, ID. Wednesday's high was 100 degrees at Laredo, TX.
ALASKAN WEATHER -- Much of Alaska was cloudy on Wednesday, courtesy of several low pressure systems. One storm system was situated in the northern Gulf Coast to the south of the Kenai Peninsula. An occluded front spiraled outward from the low before splitting into a warm front that extended eastward to the southern portions of the Panhandle and a cold front that extended southward over the North Pacific Ocean. A weak low pressure system was located along the Seward Peninsula, accompanied by clouds that extended across the northwestern portion of the state. Another storm system located in the western Bering Sea was responsible for wide spread clouds across the Aleutians and the Pribilofs. Much of the precipitation that fell across Alaska on Wednesday was found along the Gulf coast from Kodiak Island to Yakutat. The greatest amount was 0.85 inches at Valdez. Snow fell overnight but changed to rain during daylight hours. Winds gusted to 36 mph to near Delta Junction and to 32 mph at Healy, near Denali National Park during Wednesday. As a result, wind advisories were in effect through Wednesday night for the Tanana Valley near Delta Junction and for the passes in the Alaska Range. Breaks in the overcast were reported over portions of interior and northeast Alaska as a ridge of high pressure centered over British Columbia.
The lowest overnight temperature in the state as of Wednesday was 28 degrees below zero at Wainwright. The midafternoon state highest temperature was 48 degrees at Eagle, Eielson AFB, Nenana and Talkeetna.
HAWAIIAN WEATHER -- Some isolated showers lingered over the islands on Wednesday afternoon as a drier air mass was beginning to reach Hawaii. On Tuesday, 2.56 inches of rain fell at Hilo, a 24 hour record for the date. An urban and small stream flood advisory for the Hilo area was posted through late Tuesday evening, when it was allowed to expire. After weakening during the first half of the week, trade winds should begin to increase in speed on Thursday as a ridge of high pressure moves north of the islands.
A TITANIC EVENT -- Thursday marks the 87th anniversary of the sinking of the British steamer Titanic following the collision with an iceberg in the North Atlantic on its maiden voyage in 1912. The collision occurred at about 11:45 PM on 14 April and the ship sunk during the early morning hours of the 15th. Reports showed 1500 people lost their lives in this accident. As result of this disaster, an International Ice Patrol was established to monitor the iceberg hazards in the North Atlantic. Much of the effort is conducted by the U.S. Coast Guard.
A POINT TO PONDER -- Today federal income taxes are due. Did you know that the current base operational budget for the National Weather Service is approximately $663 million, which translates to a service that provides local warnings and forecasts, as well atmospheric and hydrological research, but costs each U.S. citizen approximately $2.40 per year? Good luck finishing that Form 1040.
INTERPRETING FORECAST CHARTS -- For a description of how to read and interpret the Forecast charts on the Online Weather Homepage, you can read the optional Thursday Supplemental Information.
From the files of the Aviation Weather Center, Kansas City, MO and Intellicast
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Prepared by Edward J. Hopkins, Ph.D., email hopkins@meteor.wisc.edu
© Copyright, 1999, The American Meteorological Society.