RED HOT IN FLORIDA -- The fire danger continues to become more serious across Florida and adjacent portions of Georgia and Alabama as many areas have experienced insufficient rain. Some locations have not had measurable rain during the month of April. Wildfires burned several thousand acres on Tuesday. While slightly cooler conditions did prevailed across the Florida Peninsula on Tuesday following the passage of the cold front, the high of 91 degrees at Fort Myers tied a daily record high temperature. Little relief is in the immediate future.
COOL ACROSS THE EAST -- An elongated ridge of high pressure centered over Lake Michigan and extending southward to the Gulf Coast as of Tuesday night help bring cool and dry weather across the Northeast. The clockwise circulation around the high produced northerly winds across New England and the Middle Atlantic States. A strong pressure gradient between the high and a low pressure system east of the Maritimes produced strong northerly winds that reduced wind-chill equivalent temperatures.
Light snow was reported over northern Maine from Atlantic moisture being brought around the north side of the low pressure system on northerly winds.
SEVERE WEATHER MOVES ACROSS THE SOUTHERN PLAINS -- A line of severe thunderstorms moved across Texas, in the vicinity of Midland and Abilene on Tuesday night. According to indications from Doppler radar, some of these thunderstorms may have spawned tornadoes across this region. An unconfirmed tornado caused damage in a town near Midland. Earlier in the afternoon, thunderstorms produced hail in a relatively small band from the Texas and Oklahoma Panhandles into Kansas.
The strongest of the severe thunderstorms formed into an organized line called a squall line. This squall line was found in the warm sector region to the east of a surface low pressure system that was located in the Texas Panhandle near Amarillo. A warm front extended eastward along the Red River Valley, while a cold front trailed southward over the Big Bend into Mexico. A southeasterly wind brought warm moist Gulf air across Texas to help fuel the thunderstorms. Dewpoints across the warm sector were in the 60s and 70s. To the west of the cold front, dewpoints were in the teens and 20s. Such humidity contrasts can, like differences in temperature along a cold front, provide sufficient density differences to serve as a trigger for thunderstorms.
To the north of the warm front, a wide area of rain stretched from Colorado eastward to the Mississippi. The heaviest rains were across Kansas.
The storm system is forecast to move eastward, reaching the Red River between Texas and Oklahoma by Wednesday morning. The cold front should be approaching the Dallas-Fort Worth and San Antonio metropolitan areas. As the cold front moves east, the region with a slight risk of severe thunderstorms shifts eastward across central and north Texas and essentially all Oklahoma by morning. This risk area should move east into the lower Mississippi Valley later in the day.
THUNDERSTORMS RUMBLE ACROSS THE NORTHERN PLAINS -- Thunderstorms also were found over the Dakotas ahead of a cold front that moved across the northern Plains. This cold front was associated with a low pressure system that was moving eastward across the Prairie Provinces. By Wednesday morning, the cold front and the accompanying precipitation is expected to be found across the upper Misssippi Valley. The precipitation along the southern extremeity of the cold front is forecast to interact with the precipitation shield associated with the storm system in the southern Plains.
CLEAR SAILING AHEAD? After many weeks of cold, stormy weather that affected the West Coast, residents along the West Coast have several days of tranquil and warmer weather. Essentially cloud-free skies were reported over much of the West, courtesy of a large ridge of high pressure, the center of which was situated near Vancouver Island. The clockwise circulation around the high produced downslope and offshore winds from the northeast that help suppress clouds and warm the air through compressional heating.
UPPER AIR -- The 00Z Tuesday upper air charts continue to indicate a cold pool of air that extends from the surface up to the upper troposphere, to the vicinity of the 300 mb surface. This cold air, associated with a trough of lower heights on the respective charts, has moved eastward to over New Mexico from a position over the Pacific coast 24 hours previously. The trough on both the 300 and 500 mb charts corresponds to the surface low pressure center over the Texas Panhandle. A ridge of higher heights on these pressure surfaces has begun to appear along the West Coast as warm air returns to that region. A trough over New England continues and indicates cold air through the troposphere, associated with the surface low over the Maritimes.
TEMPERATURE EXTREMES ACROSS THE LOWER 48 -- On Tuesday, the lowest temperature reported in the continental U.S. was 18 degrees at Jackson, WY. Tuesday's high was 97 degrees at Laredo, TX.
ALASKAN WEATHER -- Many areas of Alaska experienced clouds on Tuesday as several low pressure systems affected the state. One low was located over southwest Alaska north of King Salmon, with a cold front trailing across the Alaska Peninsula. Another weak low was found over the Seward Peninsula. Snow fell in the northerly winds across the western half of Alaska. Between 3 and 5 inches of snow were reported in the Anchorage Bowl. In southeast Alaska, rain fell, with Yakutat recording a third of an inch. A stationary front oriented in an east-west direction remained across northern Alaska. Weak high pressure was located over the southeast, an extension of a ridge of high pressure that was located off the coast of Vancouver Island. As a result, partly cloudy skies were found over south central and interior sections of southeast Alaska.
Because of the pressure gradient between the high over British Columbia and the low over southwest Alaska, strong winds with gusts to 30 mph were found across portions of southeast Alaska, stretching from the Copper River Basin to Denali Park
The lowest statewide overnight temperature on Tuesday was 27 degrees below zero at Nuiqsut. The highest temperature in the state as of midafternoon was 48 degrees at Eagle.
HAWAIIAN WEATHER -- Easterly trade winds slackened over Hawaii on Tuesday as a high pressure cell to the northeast of the islands continued to weaken. As a result, the small craft advisories for state waters were canceled at noon. Showers and isolated thunderstorms continued over the slopes of the Big Island and Maui into Tuesday afternoon, but should diminish as a more stable air mass approaches. An increase in the trade winds is expected late Wednesday as another high pressure system approaches north of the islands.
TRACKING THE STORMS: HANDS-ON EXERCISE -- Learn how to track storm systems as well as high pressure systems in Wednesday's optional 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.