WET WEATHER MOVES TOWARD THE NORTHEAST -- The low pressure system that was located over the mid-Mississippi Valley on Monday night moved eastward along the Ohio River on Tuesday. By Tuesday night the low pressure center was located near Cincinnati, OH. A stationary front stretched eastward circuitously around the Appalachians, while a cold front trailed southwestward to the lower Mississippi Valley before curving westward to become a stationary front in west Texas. A broad area of precipitation associated with this system extended from the Ohio Valley near the low pressure center northeastward across Pennsylvania and New York State into southern New England. Most of this precipitation was in the form of steady rain. To the south of the low pressure system, rain and some embedded thunderstorms were found along the cold front, stretching southward to central Alabama.
By Wednesday morning the low pressure system is expected to have continued eastward, reaching the Upper Potomac River Valley of northern Virginia and western Maryland. The associated precipitation shield is anticipated to reach from the Chesapeake Basin northward to Upstate New York and northern New England. Rainfall on the order of 0.25 inches could fall over this region in the 24 hours ending on Thursday morning, with as much as 2 inches of rain across coastal Maine as the low reaches the East Coast.
ACTIVE WEATHER CONTINUES IN TEXAS -- Thunderstorm activity continued across west Texas and southeastern New Mexico in association with the western terminus of the nearly stationary cold front. Some of the thunderstorms became severe on Tuesday afternoon and evening. Hail with diameters reaching 1.75 inches fell at Marfa in west Texas, with smaller diameter hail reported at Roswell, NM. Winds reached 60 mph at Carlsbad, NM. Because of the heavy rains from the thunderstorms, a flash flood watch was in effect on Tuesday night for the Permian Basin of west Texas and some of the adjoining counties of New Mexico.
Farther south along the Gulf Coast and the lower Rio Grande Valley, rain and thunderstorms continued along the front that marked the boundary between the warm, humid air over the Gulf and cooler and drier air over northern Texas. Rainfall amounts across south Texas have been impressive, ranging between 3 and 4 inches. Near San Antonio, nearly 6 inches had fallen by midday. The cold front is expected to continue its movement southward out over the Gulf on Wednesday. Between 0.25 and 0.50 inches of rain could fall along the Rio Grande Valley of south Texas on Wednesday.
PLEASANT WEATHER ACROSS THE PLAINS -- High pressure dominated the weather across the nation's midsection, resulting in tranquil weather from the Great Lakes westward to the Intermountain West and southward to the Lower Mississippi Valley. The warm front moving eastward across the Upper Mississippi Valley in association with a low pressure center over northwestern Ontario produced some clouds and light precipitation over the Arrowhead of Minnesota. Because of the lack of moisture, the cold front moving into the Dakotas and adjoining sections of Minnesota and Montana represented more of a wind-shift line.
The low pressure system over Ontario is expected to move eastward, reaching southern James Bay by Wednesday morning. The trailing cold front should have reached Michigan's Upper Peninsula and northern Wisconsin.
STORMY WEATHER ACROSS THE PACIFIC NORTHWEST -- A deep low pressure system passing northeastward near northern Vancouver Island produced strong winds and precipitation across western Washington and Oregon on Tuesday evening. Warm air was being carried northward as southerly and southwesterly winds to the east of the low pushed the warm front into British Columbia and Alberta. Sustained southerly winds of 35 mph with gusts to 50 mph were reported in the San Juan Islands of Washington's Puget Sound.
The cold front trailing from the low pressure system is expected to pass across the Olympic Peninsula and Puget Sound during the early hours of Wednesday. By later in the morning, the cold front should be in eastern Washington and Oregon, as the low pressure system continues to move toward northeastern British Columbia. Gale warnings for winds between 39 to 54 mph were posted for the Oregon and Washington coasts northward from Cape Blanco, OR, through the Strait of Juan de Fuca to Cape Roberts, WA. As the colder air moves onshore, the precipitation should diminish, but snow levels are expected to fall to elevations of 5500 feet by Wednesday.
YESTERDAY'S TEMPERATURE EXTREMES ACROSS THE CONTINENTAL US --Tuesday morning's lowest temperature was 13 degrees at Fraser, CO, while the highest temperature on Tuesday was 95 degrees at Death Valley and El Centro, CA.
ALASKAN WEATHER -- A broad area of low pressure dominated the weather across much of Alaska on Tuesday afternoon. The only exception was the weak region of high pressure across the east central Aleutians. The main low pressure center was located across southwestern Alaska near Bethel. An associated trough line extended northeastward to Fairbanks and then to the Yukon Territory, while a westward extension continued into the Bering Sea, passing near Nunivak Island. A weakening low pressure center was located over the Gulf of Alaska south of the Kenai Peninsula. Another low pressure located to the west of Prince Rupert, BC was moving to the northeast, close to southern tip of the Panhandle. Snow and fog were found across the North Slope, to include Barrow. Snow also was reported at Kotzebue. Rain fell at Cold Bay, Cordova and Yakutat.
The state's lowest overnight temperature on Tuesday morning was 8 degrees at Nenana, Northway and Tanana. The highest temperature by mid afternoon of Tuesday was 54 degrees at Hydaburg.
HAWAIIAN WEATHER -- Pleasant trade weather with relatively cloud-free skies and isolated showers was found across the islands on Tuesday afternoon as an east-west oriented ridge of high pressure remained approximately 500 miles north of Oahu. This weather regime should continue through early Wednesday. However, a tropical disturbance in the trade wind flow with an associated band of showers was moving to the west toward the Big Island. The showers associated with this disturbance should reach the Big Island by Wednesday afternoon and the other islands on Thursday. These showers are expected to be heavy on the windward slopes of the Big Island and Maui. As the disturbance in the trades moves westward, the speed of the trades should increase, then decrease following its passage.
EYE ON THE TROPICS -- The tropical disturbance that formed Monday between the Bahamas and Bermuda intensified into Tropical Storm Michael, the thirteenth named tropical cyclone (tropical storms and hurricanes) on Tuesday morning. By early evening, Michael had intensified sufficiently to be classified as the eighth hurricane of the season. As of late Tuesday night, Michael was a minimal hurricane with sustained near-surface wind speeds of 75 mph and it was 385 miles west-southwest of Bermuda, moving slowly to the north-northeast at 3 mph. Michael produced east to northeast swells ranging from 4 to 6 feet along the East Coast of the US from Florida north to include the Carolinas. A buoy moored 275 miles east-southeast of Mrytle Beach, SC reported 7 foot swell. This swell is expected to continue through at least Wednesday. Dangerous rip currents and undertows were also produced, with the rip currents being the most prevalent a few hours either side of low astronomical tide.
From the files of the Aviation Weather Center, Kansas City, MO and Intellicast