NATIONAL WEATHER SUMMARY

 

APRIL 2013

 

1^st-6^th…The Central U.S. began April with chilly temperatures on Monday, while wet weather continued in the East and West. A cold upper trough of low pressure from the North reached southward into the Central and Eastern U.S. and ushered another shot of arctic air into the north-central regions of the nation. This translated into well below average temperatures that seemed more reminiscent of winter than spring. As cold northwesterly flow spread into the Midwest, light to moderate lake effect snow showers developed downwind of portions of the Great Lakes. A Lake Effect Snow Warning and Winter Weather Advisory continued for areas of northern Michigan through the afternoon in anticipation of 2 to 4 inches of snow and strong northwest winds. Meanwhile, rain and snow showers developed from upstate New York through the central Appalachians as a cold front over the Upper Midwest pushed eastward toward the Atlantic Ocean during the afternoon. South of this cold front, a second cold front became nearly stationary from the Lower Mid-Atlantic through the Deep South. Rain showers and isolated thunderstorms continued along and ahead of this cold front through the afternoon. Further south, impulses streaming across the southern Florida Peninsula created a slight risk of severe thunderstorm activity during the late afternoon. While the main concern with these storms were severe hail, tornadoes were not ruled out.

Out West, outside of a residual showers in California, rain and high elevation snow moved into the Great Basin and reached the Central Rockies on Monday as the Pacific storm that impacted the West Coast on Sunday moved inland. Isolated rain showers and thunderstorms began to develop from the northern Texas Panhandle into southern Kansas this afternoon as an associated cold front reached southeastward into northeastern New Mexico and the Texas Panhandle. Areas of the Southern Plains were at slight risk of severe weather development with severe hail and damaging wind gusts through the afternoon and evening.

Showers and thunderstorms diminished in the Southeast on Friday, while areas of wet weather persisted for the West. A strong low pressure system over the Gulf of Mexico moved over Florida and into the Atlantic Ocean early in the day. This allowed for showers and thunderstorms across Georgia and the Carolinas to taper off throughout the day, while a cold front to the south of this system brought more heavy rains and strong thunderstorms to Florida and the Bahamas. Severe storms have not yet been reported in these areas but hail and strong winds remained a threat. Mid-day rainfall totals ranged from 1 to 2 inches across central and southern Florida by Friday afternoon. Out West, a low pressure system moved over the western states continued to push a cold front eastward through the Intermountain West, Great Basin, and into the Northern and Central Rockies. This brought rain and mountain snow showers to these areas, while the leading edge of this system pushed a combination of rain and snow into the Dakotas and Minnesota. Scattered rain showers also continued along the back side of this system in Oregon and Washington. Some areas of Oregon and Washington saw another inch of rain by mid-day Friday.

 

7^th-13^th…A significant snowstorm continued in parts of the West and Plains on Tuesday, while chances of severe weather activity heightened in the Great Plains. A strong storm system over the Intermountain West shifted eastward on Tuesday as a strong cold front reached from the central Plains across the central and southern Rockies and a strong low pressure system moved into Texas. Heavy snow showers fell across areas of Colorado, Wyoming, western Nebraska, and South Dakota, while strong winds gusting in excess of 50 mph picked up across the region through the day. This combination of snow and wind translated into blizzard conditions in parts of eastern Colorado through Tuesday night with lowered visibility, high snow drifts, icy roads, and hazardous travel conditions. Much of this wintry weather region and portions of southwestern Minnesota remained under Winter Storm Warnings and Winter Weather Advisories in anticipation. Blizzard Warnings continued for the mountains of Colorado through Tuesday evening. In addition to snow and wind, areas of morning freezing rain and sleet in Nebraska and parts of South Dakota led to possible ice accumulations of up to an inch. Meanwhile, warm and moist air from the Gulf of Mexico streamed northward and supported more rain and thunderstorms from the central Plains into the Ohio Valley and Great Lakes. This moisture tap continued the threat of severe weather development from the southern Plains through the Mid-Mississippi Valley.

A powerful storm continued to move through the Plains toward the Mississippi Valley Wednesday. The associated cold front moved eastward, instigating a mixture of rain and snow in the Plains. As the cold front approached the Mississippi Valley, it gathered considerable moisture from the Gulf of Mexico that produced severe thunderstorms. Tornado Watches were posted through Arkansas, southeast Missouri, and southern Illinois due to the possibility of developing tornadoes. Residents should monitor the progress of these thunderstorms into the evening and be prepared to protect life and property from these dangerous storms. Farther to the north, strong thunderstorms also swept through the Ohio Valley and produced another area of dangerous weather. Even without severe weather, several inches of rain fell from Oklahoma and Kansas through Arkansas and Missouri as the main cold front swept through the region. Snow finally subsided in the Rockies and Northern Plains, allowing residents to begin the process of digging out from this strong Spring storm. Some areas of South Dakota received over two feet of snow from this storm. Very warm temperatures in the 80s and 90s were experienced ahead of the main storm from the Southeast through the Mid Atlantic. Several records were broken, with numerous more anticipated to be broken by the end of the day. The Northeast saw a range of temperatures from the 40s to the 80s, while the Northern Plains rose into the 30s and 40s. The Northwest rose into the 50s and 60s, while the Southwest saw temperatures in the 70s and 80s.

Rain moved through the Northeast, while rain and snow persisted for the Upper Midwest, and showers and thunderstorms diminished across the Southeast. A strong low pressure system that created a strong winter storm for the Plains and Upper Midwest continued to move northeastward and over the Great Lakes. This brought snow showers to the Great Lakes and Upper Midwest, which turned to rain showers as temperatures warmed throughout the day. The leading edge of this system pushed a warm front northward through the Northeast, creating heavy rain and periods of freezing rain from New Jersey and New York through Maine. At the same time, a strong cold front extended southward from this system and advanced eastward across the Eastern Valleys. This system has brought severe thunderstorms to the South the past three days, and finally started to push offshore and into the Atlantic Ocean. A few widespread scattered showers and thunderstorms developed from Maryland, through the Carolinas, and into Georgia. Some of these storms turned severe with strong winds and large hail. Behind this system in the West, a low pressure system moved over the Rockies and kicked up scattered showers that moved into the High Plains. Significant rainfall has not been reported, but strong and gusty winds developed across Idaho, Nevada, and into Utah. Some areas saw gusts up to 55 mph.

 

14^th-20^th...A dangerous day was set up for the middle portion of the country Wednesday as a powerful storm brought a variety of significant weather events to the region. The associated cold front produced heavy rain for Iowa and Illinois. Some areas in Iowa had reported up to 3 inches of rain by the early afternoon, prompting flooding concerns due to surging rivers and streams. The second effect of the storm was the winter conditions it provided from the Northern Rockies through the Northern Plains. While significant snow was expected to continue to produce significant snow into the evening and Thursday, several inches of snow had already fall from eastern Colorado through South Dakota. Meanwhile, an area of showers and thunderstorms developed over the Appalachians. The rest of the eastern third of the county remained dry. The Southeast rose into the 70s and 80s, while the Northeast saw temperatures in the 50s and 60s. The Northern Plains rose into the 30s and 40s, while the Northwest saw temperatures in the 40s and 50s.

A strong winter storm lingered over the Great Lakes on Friday, while the associated cold front brought severe thunderstorms to the Eastern states. A low pressure system continued moving northeastward, over the Great Lakes and toward eastern Canada. The back side of this system allowed for cool air from Canada to pour across the Upper Midwest, allowing for a few more snow showers to persist for northern and eastern Minnesota, as well as most of Wisconsin and the Upper Peninsula of Michigan. Most of the heaviest snowfall came to an end early Friday morning with record breaking snowfall totals for many areas of northern Minnesota and Wisconsin. Storm totals since Wednesday reached up to 20 inches for some areas, with 17.70 inches of snow reported at Duluth, Minnesota. This past snowstorm created the snowiest April on record for Duluth at 41.7 inches.

At the same time, the strong low pressure system continued pushing a cold front through the Eastern states. This system has a history of producing multiple tornadoes with many reports of strong winds and large hail. By mid-day Friday, one tornado was reported in Mansfield, Georgia with many reports of damaging winds across Alabama and Georgia. Severe flooding continued for the Ohio River Valley and Mid-Mississippi River Valley as the cold front created heavy rains for the region yesterday. Two day rainfall totals for much of Illinois ranged from 5 to 7 inches. This created major flooding concerns for the region, with many areas experiencing record flood levels. Meanwhile, out West, another storm system dropped into the Pacific Northwest from the Gulf of Mexico. This brought moisture onshore, which kicked up rain showers through the Intermountain West and Northern Rockies. Snow showers developed at highest elevations in parts of Idaho and western Montana.

 

21-30^th…A strong cold front brought showers and thunderstorms to the eastern Valleys on Wednesday, while scattered snow showers moved across the Northern Plains. A low pressure system that brought a strong winter storm to the Upper Midwest early this week has moved eastward over the Great Lakes. The back side of the system continued pushing a cold front eastward, kicking up showers and thunderstorms from the Great Lakes through the Gulf coast. Some of these storms have turned severe with heavy rainfall and strong winds. A threat for large hail and tornadoes persisted for the Lower Mississippi River Valley as the system pulled moisture and energy in from the Gulf of Mexico. There have been multiple reports of trees and power lines blown down across Louisiana and Tennessee. Rainfall totals reached over an inch in these areas which allowed for flooding to remain a concern for the Ohio River Valley and Mississippi River Valley. Record level flooding was reported at Peoria, Illinois where the Illinois River was up to 29.35 feet on Wednesday morning. Since the rain last week, at least 20 locations in the Midwest have reached record flood levels. Behind this system in the North, a trough of low pressure dipped into the Northern Plains from central Canada. This system brought cool air into the region in addition to some moisture and allowed for widespread scattered snow showers to develop from eastern Montana through North and South Dakota, and into Minnesota. Snowfall totals remained light with 1 to 2 inches reported in most areas, while record low temperatures were observed. Bismarck, North Dakota dropped to 12 degrees early Wednesday morning. The previous record was 16 degrees set in 1988.

Severe showers and thunderstorms developed across the South on Friday. A trough of low pressure moved off the Southern Rockies and into the Southern Plains, which pulled moisture in from the Gulf of Mexico. This system allowed for showers and thunderstorms to develop from Texas through Oklahoma that advanced eastward across the Mid-Mississippi River Valley and into the Tennessee Valley throughout the day. Rainfall totals in these areas ranged around an inch by mid-day on Friday. Some areas saw periods of heavy rainfall and gusty winds. To the north, a few widespread showers persisted across the Great Lakes as a system slowly exited the region. Elsewhere, high pressure over the East Coast maintained dry and pleasant conditions. The Northeast saw highs in the mid-60s, while the Southeast approached the 80s. High pressure also dominated the West Coast and created a mostly sunny and dry day. The Pacific Northwest saw a sunny day with highs in the 70s, while the Southwest reached into the lower 80s.

Wet and unsettled weather developed in the Eastern Seaboard on Monday as low pressure reached the Lower Great Lakes and a wave of upper level energy moved across the southern Mid-Atlantic. This weather setup spread light to moderate scattered showers from the Ohio Valley into the Northeast and the Upper Mid-Atlantic. Heavier precipitation along with isolated thunderstorms picked up across the Mid-Atlantic through the morning and afternoon, from areas of northeastern South Carolina into southeastern Pennsylvania and southern New Jersey. Meanwhile, the southern stream of this system continued to impact areas of the Gulf Coast, from southern Texas through the southeastern coast, with light to moderate showers and isolated thunderstorms. Locally heavy rainfall and thunderstorms with strong winds were possible over the southern tip of Florida. To the north, a cold front dropped into the Upper Midwest with waves of low pressure and sufficient moisture. This translated into scattered showers and chances of isolated thunderstorms with gusty winds ahead of the cold front from the Upper Great Lakes into Iowa and northern Illinois. Areas of far northeastern Kansas across northern Missouri, eastern Iowa and southern Wisconsin were at slight risk of severe thunderstorms that were capable of producing damaging wind gusts and large hail. Elsewhere in the North, snow showers developed in the higher elevations of the Northern Rockies, while a strong cold front moved into the Pacific Northwest with rain and high elevation snow.

Jim G. Munley, jr.
http://www.jimmunleywx.com