Friday Daily Weather Summary

ONLINE DAILY WEATHER SUMMARY

Friday, 9 April 1999

SEVERE WEATHER DEVELOPS ACROSS THE CENTRAL STATES
THUNDERSTORMS IN THE SOUTHEAST
A SECOND SYSTEM FOLLOWS
UPPER AIR
YESTERDAY'S TEMPERATURE EXTREMES IN THE LOWER 48
ALASKAN WEATHER
HAWAIIAN WEATHER
HISTORICAL WEATHER EVENTS

SEVERE WEATHER DEVELOPS ACROSS THE CENTRAL STATES -- A potent storm system that was accompanied by tornado-producing thunderstorms developed on the eastern slopes of the Rockies early Thursday and moved eastward across the Plains. As of late Thursday night, the low pressure center was located in the Missouri Valley near Omaha, NE. The system was just beginning to occlude as an occluded front extended eastward for approximately 100 miles from the low pressure center before splitting into a warm front that continued to the east-southeast toward the Ohio Valley and a cold front that initially traveled southward to northwest Arkansas before curving southwestward into north Texas.

Severe thunderstorms with high winds and large hail developed moved across an area that extended from eastern Nebraska to western Illinois and from southern Missouri to northern Iowa. Several thunderstorms spawned tornadoes. More than a dozen confirmed tornadoes were reported across Iowa and Missouri as of late Thursday night. Additional tornadoes remained a possibility from Illinois and Indiana southward into Arkansas into early Friday morning.

These thunderstorms developed as southerly winds in the warm sector to the southeast of the surface low pressure system drew warm moist air in to the storm. Cold dry air aloft also contributed to the destabilization of the atmosphere.

To the north of the system, an extensive precipitation shield stretched from the southern Great Lakes westward into the Missouri Valley. Some areas across Wisconsin, northern Iowa and southern Minnesota received more than an inch of rain from the system. Several rivers, to include the Iowa River at Marshalltown, IA, were rising toward flood stage as a result of nearly 3 inches of rain.

Strong non-thunderstorm winds were also associated with this storm system. Several locations along the Colorado Front Range had non-thunderstorm wind gusts greater than 70 mph on Thursday morning. Niwot Ridge reported a wind gust to 112 mph, while the Jefferson County Airport near Boulder had a 92 mph gust. The strong pressure gradient revealed by the tight packing of the isobars on the west side of the storm would suggest strong winds have continued across the Plains into late Thursday night.

This system is expected to continue toward the east, undergoing an occlusion process as it moves. The primary low pressure center should be located over northwest Illinois, with the cold front extending southward through Indiana and into the lower Mississippi Valley. The threat of severe weather is forecast to move eastward into the Indiana and the Ohio Valley.

THUNDERSTORMS IN THE SOUTHEAST -- Thunderstorms with large hail and high winds also developed in eastern Kentucky and West Virginia in the Ohio Valley and across the Carolinas, where wind damage was reported. The opening round of the PGA Master's golf tournament in Augusta, GA was delayed by thunderstorms.

Unseasonably warm conditions were found along the Eastern Seaboard. Afternoon high temperatures in the Middle Atlantic States were as much as 20 degrees above the climatological average high temperatures for the date. Farther south, record high temperatures were set on Friday in South Carolina at Florence (90 degrees), Charleston/Airport (90 degrees) and Beaufort (89 degrees); in North Carolina at Wilmington (89 degrees) and Raleigh-Durham (88 degrees) and at Savannah, GA (89 degrees). Along the Gulf Coast a warm, humid air mass kept overnight low temperatures from falling too far. At Houston (Intercontinental), TX the minimum temperature as of Thursday morning was only 74 degrees, a record high low temperature for the date.

A SECOND SYSTEM FOLLOWS --- The next storm that may produce severe weather later in the weekend was located over the Intermountain West. This system had moved inland from the West Coast late Wednesday night. On Thursday night this storm system was located in the Snake Valley of Idaho, with a cold front that extended southward across Nevada into southern California. Widely scattered precipitation was associated with this system, with valley rain and high elevation snow across the West. Several inches of snow were anticipated in the Blue Mountains of northeast Oregon.

This system helped bring more cold air into the Southwest. With a fresh snow cover, Thursday morning's low temperature at Flagstaff, AZ was a record-tying 14 degrees. Afternoon high temperatures along the West Coast and into the Southwest were between 10 and 15 degrees below the long-term average low for this time of year. The high temperature at Downtown San Francisco was only 50 degrees, a record low maximum for the date.

By Friday morning the storm system is forecast to be located across the Uintas of northeast Utah. A wide spread area of snow should be found over the Great Basin and along the Rockies. A winter storm warning was posted for the as much as a foot of snow in the Wasatch Front in Utah. High wind watches were in effect for New Mexico.

UPPER AIR -- The upper air charts for 00Z on Friday reveal the vertical structure of an occluding storm system in the nation's midsection. When a storm occludes, the system becomes "vertically stacked" in that at essentially any level in the troposphere, the counterclockwise circulation is around a central point that is essentially above the low pressure center at sea-level. In the current case, a height low identified by the closed height contours on both the 500 mb and 300 mb charts was found over Omaha, NE. A distinct counterclockwise circulation in the winds can be visualized on the 500 mb chart, with strong westerly winds to the south of the low across Kansas, while easterly winds were observed on the north side, over the Dakotas. A closed circulation regime is not as apparent at 300 mb. However, at this upper-tropospheric level, the spreading of height contours on the downwind or east side of this height trough over Iowa provides a hint as to the divergence of the upper level winds which help maintain not only the surface low pressure regime, but also help create an environment needed for the development of severe thunderstorms. A jet streak with winds in excess of 110 knots is apparent from the Texas Panhandle to southwest Missouri.

Farther west, a pool of cold air over the Eastern Pacific is apparent as a deep trough on both the 500 and 300 mb charts. The orientation of the isotherms, the height contours and the southwesterly winds suggest that this feature must be off the West Coast.

YESTERDAY'S TEMPERATURE EXTREMES IN THE LOWER 48 -- The lowest temperature on Thursday was 14 degrees at Flagstaff, Springerville and Williams, AZ, while the day's high was 99 degrees at Laredo, TX.

ALASKAN WEATHER -- A large storm system with an elongated center dominated the weather across southwest Alaska on Thursday afternoon. The low pressure center was located over the Bristol Bay, but stretched southeastward across the Alaska Peninsula. A front extended from this low pressure center to the southeast across the North Pacific. A winter storm advisory was in effect for Bristol Bay and the Kuskokwim Delta. As a result of the strong pressure gradient surrounding this storm system, strong winds were found across much of southwest Alaska. St. Marys had gusts to 60 mph, with wind-chill equivalent temperatures falling to 27 degrees below zero, where Cold Bay and Dutch Harbor had winds exceeding 50 mph. A wind advisory was in effect for the Pribilofs, the Alaska Peninsula from Dutch Harbor to King Salmon and portions of the Kuskokwim Delta.

While most of the precipitation across the state was very light, with amounts less that one tenth of an inch, Cold Bay reported 0.24 inches in 18 hours on Monday.

The lowest overnight temperature in the state on Thursday was 17 degrees below zero at Cantwell, Denali Park and Wainwright. The highest statewide temperature in midafternoon was 48 degrees at Klawok.

HAWAIIAN WEATHER -- An intense high pressure center was moving to a position to the northeast of the islands. As a result, the northeast trade winds had strengthened in intensity. Showers upwind of the islands were expected to arrive at the islands early on Friday morning. With the anticipated increased trade winds, gale warnings in the channels may be issued late Friday. As of Thursday afternoon, small craft advisories continued for state waters.

HISTORICAL WEATHER EVENTS - 9 April

From the files of the Aviation Weather Center, Kansas City, MO and Intellicast

...1947... The Southern Plains Tri-State tornado tracked 170 miles through Texas, Oklahoma, and Kansas. This tornado episode was probably a family of tornadoes, with 181 fatalities, 970 injuries, and $9.7 million in total damage. Nevertheless, damage was at the F5 level (winds 260 mph plus). A tornado struck Woodward, OK during the late evening killing between 95 and 107 persons and causing six million dollars damage. The tornado, one to two miles in width, and traveling at a speed of 68 mph, killed a total of 167 persons along its 221 mile path from Texas into Kansas, injured 980 others, and caused nearly ten million dollars damage. (David Ludlum)
A man looking out his front door was swept by a tornado from his home near Higgins, TX and carried two hundred feet over trees. The bodies of two people, thought to be together at Glazier, TX, were found three miles apart. The entire town of Glazier, TX, where 17 people were killed, was destroyed and never rebuilt as a town.(David Ludlum) (The Weather Channel) (Intellicast)
...1973...A severe late season snowstorm was in progress across Iowa, southeastern Minnesota, northern Illinois, and southern Wisconsin. Wind gusts to 70 mph whipped the snow into 16 foot drifts in Iowa. Ten to 20 inches of snow were common with 20 inches falling at Grand Meadow, MN and 19.4 inches piling up at Dubuque, IA. (Intellicast)
...1977...A storm brought 15.50 inches of rain to Jolo, WV in thirty hours. (The Weather Channel)
...1987...International Falls, MN reported their sixth straight record high for the date, with a reading of 77 degrees. A cold front ushering sharply colder weather into the north central U.S. produced wind gusts to 60 mph at Glasgow, MT. (The National Weather Summary)
...1988...Residents of Sioux City, IA awoke to find two inches of snow on the ground following a record high temperature of 88 degrees the previous afternoon. (The National Weather Summary)
...1989...Eighteen cities in the southwestern U.S. reported new record high temperatures for the date. The afternoon high of 80 degrees at Eureka, CA established a record for the month of April. (The National Weather Summary)
...1990...Thunderstorms developing ahead of a cold front produced severe weather from the Central High Plains to Arkansas and northern Texas. Severe thunderstorms spawned five tornadoes, and there were seventy reports of large hail and damaging winds. A tornado injured four persons at Ardmore, OK, and thunderstorms produced wind gusts to 70 mph at Kellyville, OK, and hail three inches in diameter at Halmstead, KS. (The National Weather Summary) (Storm Data)
...1991...A large portion of the east was battered by severe thunderstorms with 503 severe weather events reported. Thirty eight tornadoes touched down with the most significant one beginning its 18 mile path at Guthrie, KY. This tornado, rated F2, did over $500,000 in damage. Three inch diameter hailstones fell in Switzerland County in Indiana. Two people were killed and 86 were injured from intense straight line thunderstorm winds exceeding 100 mph in West Virginia. Gatesburg, PA reported a wind gust to 90 mph. (Intellicast)
...1995...Glasgow, MT recorded 12.2 inches of snow in 24 hours -- its greatest 24 hour snowfall on record. (Intellicast)

10 April

...1877... The first of two great coastal storms struck the Virginia and North Carolina coast. The Oregon Inlet was widened by three quarters of a mile. The "entire topography of country is materially altered", according to a description of the altering of sand dunes at Cape Hatteras. (Intellicast)
...1894...A heavy late season snow blanketed parts of the northeastern U.S. Heavier snowfall totals included 31.5 inches at Salem Corners, PA, 30 inches at LeRoy, NY, 26 inches at York, PA, 14 inches at Waterbury, CT, and 9 inches at Providence, RI. (The Weather Channel)
...1935...Severe dust storms across Iowa and Kansas closed schools and highways. Dodge City, KS experienced its worst dust storm of record, with dense dust reported from the morning of the 9th until after sunset on the 11th. The sky was almost as dark as night at times during the daylight hours. The thick dust suspended traffic on highways and railroads, and also suspended most business in town. (The Weather Channel)
...1979...An outbreak of 23 tornadoes ravaged the Red River areas of Texas and Oklahoma. This day was known as "terrible Tuesday" to the residents of Wichita Falls, TX as a tornado rated F4 on the Fujita scale ripped through the city. Forty two people were killed, 3095 homes were destroyed in Wichita Falls and total damage was set at $400 million, making it the most costly tornado in history. The tornado width reached 1.5 miles as it passed through the residential section of the city. Another tornado struck Vernon, TX killing eleven persons. (David Ludlum) (Storm Data) (Intellicast)
...1985...A late season cold snap in the east set record low April temperatures in the following cities: Asheville, NC, 23 degrees; Beckley, WV, 11 degrees; Elkins, WV, 3 degrees. April record lows were tied in Raleigh-Durham, NC (23 degrees) and Roanoke, VA (20 degrees). (Intellicast)
...1987...Blustery northwest winds prevailed across the Northern Plains Region. Winds in Wyoming gusted to 65 mph. Temperatures in North Dakota were only in the 20s and 30s, following afternoon highs in the 70s the previous day. (The National Weather Summary)
...1988...Unseasonably warm weather prevailed in the western U.S. Eleven cities reported new record high temperatures for the date, including Bakersfield, CA with a reading of 95 degrees, their warmest for so early in the season. Pocatello, ID warmed from a record low of 19 above to an afternoon high of 63 degrees. (The National Weather Summary)
...1989...Strong northerly winds, gusting to 53 mph at Albuquerque, NM, ushered cold arctic air into the south central U.S. The temperature at Albuquerque plunged from 82 degrees to 29 degrees overnight. Thirty-three cities in the central U.S. reported record low temperatures for the date, including Goodland, KS with a reading of 4 degrees above zero. (The National Weather Summary)
...1990...Thunderstorms produced severe weather from the Central Gulf Coast Region to western sections of the Carolinas during the afternoon and evening. Evening thunderstorms over western South Carolina produced wind gusts to 98 mph which injured four persons at Holly Springs, and wind gusts to 100 mph which injured one person and caused half a million dollars damage north of Dacusville. (The National Weather Summary) (Storm Data)
...1996...A strong coastal storm gave New England is second heavy snowfall in only 3 days. North Foster, RI was buried under 21.5 inches of snow, while Jaffery, NH measured 21 inches. Other heavy totals included 27.4 inches on Mount Washington, NH, 20.1 inches at Ashburnham, MA, 17 inches at Windham, CT, and 12.6 inches at Brookhaven, NY. Tree damage was extensive due the heavy, wet nature of the snow. This storm took care of the remaining seasonal snowfall records as records were exceeded at the Blue Hill Observatory in Milton, MA, Worcester, MA, Concord, NH, and Bridgeport, CT. Many locations in the northeast now exceeded 120 inches for the winter season, with a few locations over 150 inches, making the winter of 1995-96 without question the snowiest winter on record for a large part of the Northeast. (Intellicast)

11 April

...1841...A big April snowstorm in the Northeast dropped 12 inches at New York City, 24 inches in New Jersey, and 18 inches in Massachusetts. The "Tippecanoe and Tyler, too" victory parade was impeded and the Marshall died of pneumonia. People went to the New York City polls through snow on the 13th. (Intellicast)
...1965...Severe thunderstorms in the Upper Midwest spawned fifty-one tornadoes killing 256 persons injuring 3331 and causing more than 200 million dollars damage. The "Palm Sunday tornadoes", a particularly vicious outbreak, tore paths of devastation through Iowa, Wisconsin, Illinois, Michigan, Indiana, and Ohio. Thirty seven tornadoes were rated F2 or greater with 18 rated F4 and 2 maximum intensity F5 tornadoes. Indiana, Ohio and Michigan were hardest hit. (David Ludlum) (Intellicast)
...1987...Ten days of flooding in the northeastern U.S. finally came to an end. Damage from flooding due to rain and snow melt ran into the billions of dollars. The collapse of the New York State Thruway Bridge over Schoharie Creek claimed ten lives. (Storm Data)
...1988...Sixteen cities in the western U.S., nine in California, reported new record high temperatures for the date. Afternoon highs of 95 degrees at Sacramento, CA and 96 degrees at Bakersfield, CA were the warmest of record for so early in the season. (The National Weather Summary)
...1989...Forty-four cities in the south central and eastern U.S. reported new record low temperatures for the date. Lows of 25 degrees at Conway, AR, 29 degrees at Dallas/Fort Worth, TX, and 22 degrees at Ozark, AR, were April records. Lows of 26 degrees at Hot Springs, AR and 31 degrees at Shreveport, LA equaled April records. (The National Weather Summary)
...1990...While showers produced heavy rain over much of the northeastern U.S., heavy snow blanketed northern Maine, with 13 inches reported at Telos Lake. Strong southwesterly winds accompanying the rain and snow gusted to 68 mph at the Blue Hill Observatory in Massachusetts. Rainfall totals of 1.04 inch at Pittsburgh, PA and 1.52 inch at Buffalo, NY on the 10th were records for the date. (The National Weather Summary) (Storm Data)