NATIONAL WEATHER SUMMARY

 

JULY 2012

 

1^st-7^th…The main weather story in the country continued to be the heat that scorched parts of the East. Afternoon temperatures once again rose into the 90s and 100s for many areas, but the hottest temperatures were noted in southern Illinois and adjacent areas of Missouri and Kentucky. This has been an historic heat wave with a number of all-time maximum temperatures set over the past weekend. Daily records are once again likely to be set today, breaking records that were just set over the past few days. Some early morning showers and thunderstorms moved through the Southeast, but these thunderstorms had diminished by the late morning. Meanwhile, a weak cold front moved through the northern Rockies, but this front was only strong enough to produce a few areas of showers in Montana and North Dakota. The Northeast rose into the 80s and 90s, while the Southeast saw temperatures in the 90s and 100s. The Plains rose into the 90s and 100s, while the Southwest saw similar temperatures. The Northwest rose into the 60s and 70s.

The historic heat wave continued in much of the central and eastern U.S. this Independence Day as hot temperatures persisted from the High Plains through the Southeast and Mid-Atlantic. Daytime temperatures climbed well into the 90s and mid-100s this afternoon, while heat index values ranged from 100 to 115 degrees. A variety of Heat Advisories, Excessive Heat Watches, and Excessive Heat Warnings remained in effect for much of the Midwest through the day. In the East, a low pressure system moved through the Northern Plains this afternoon, while the associated cold front reached southwestward into the Central Great Basin and the associated warm front extended through northern Wisconsin. Areas of showers, heavy rain, and thunderstorms developed to the north of the associated warm front in northwestern Minnesota. Areas from northern Minnesota through lower Michigan remained at slight risk of severe thunderstorm development with large hail and damaging wind gusts through the late evening as storms spread eastward. Meanwhile, a few thunderstorms developed near the central and eastern Gulf Coasts, while strong daytime heating and high instability maintained chances of shower and thunderstorm development across the eastern Valleys, Mid-Atlantic, and Southeast. Areas from the eastern Ohio Valley through western Pennsylvania, West Virginia, northern Virginia remained at slight risk of severe thunderstorm development with damaging wind and hail through this evening. Elsewhere in the East, a warm front lifted through the Northeast and created increased cloud cover with chances of showers in Maine. In the West, deep moisture flowed across the Southwest on Wednesday and supported isolated to scattered showers and chances of thunderstorms in southern Arizona and southeastern California. Rainfall amounts were expected to range between one tenth of an inch to up to one inch with heavier showers. Flood Advisories and Flash Flood Watches remained in effect for much of southeastern Arizona as heavier showers were expected to create ponding of water on roadways and flow in streams and brooks.

 

 

The record-setting heat wave in the Midwest continued Friday with temperatures once again reaching well into the 90s and 100s. The incredibly strong high pressure ridge that has been in place over the eastern half of the country for a week produced well above normal temperatures from the Plains straight through the eastern seaboard. Even the Northeast warmed above normal as New York City saw temperatures in the 90s. Numerous cities in the Ohio Valley set daily record high temperatures early in the afternoon with several more degrees of warming possible. This included cities such as South Bend, Fort Wayne, Cincinnati, and Columbus. While the heat was expected to continue for many areas Saturday, some relief might be on the way Sunday as a low pressure system brings cooler temperatures. Meanwhile, monsoon moisture streams into the Southwest and provided typical summer showers and thunderstorms in the Four Corners region. Farther to the north, a low pressure system pushed out of the Northern Rockies and into the Northern Plains. This feature provided additional rain and a few thunderstorms from eastern Montana and Wyoming through the Dakotas. The Northeast rose into the 80s and 90s, while the Southeast saw temperatures in the 90s and 100s. The Plains also saw temperatures in the 90s and 100s, while the Northwest rose into the 70s and 80s.

 

8^th-14^th…Heavy rains developed in the Deep South on Monday, while scattered showers and thunderstorms stretched along a frontal boundary in the Mid-Atlantic states. Heavy rains and strong thunderstorms developed across the Lower Mississippi River Valley as strong onshore flow persisted from the Gulf of Mexico. Some areas of southern Louisiana saw rainfall totals from 3 to 4 inches. Flooding became of concern in these areas. Heaviest rainfall was reported in Fort Polk, Louisiana with a mid-day total of 4.66 inches of rain. These storms have not yet turned severe, but were likely to produce some strong winds and possibly some large hail. To the north, a frontal boundary lingered over the Mid-Atlantic states and extended over the Mid-Mississippi River Valley. Additional moisture from the Atlantic Ocean fed energy into this system, which allowed for thunderstorms to develop across most of Maryland and parts of the Carolinas and the Virginias. Strong winds were reported up to 56 mph in South Hill, Virginia, and rainfall totals ranged from 1 to 2 inches across the region. Meanwhile in the Plains, a trough of low pressure moved off the Central Rockies and into the Central Plains. The leading edge of this system pulled moisture in from the South, which triggered showers and thunderstorms across the Southern and Central Plains. Heaviest rainfall was reported in Pratt, Kansas with a mid-day total of 1.95 inches of rain. Out West, a ridge of high pressure built over the West Coast. This kept moisture offshore and allowed for temperatures to reach into the lower 100s in the inland deserts. Coastal areas remained in the 60s and 70s.

Eastern Texas and the Southeast saw more heavy rain on Friday, while monsoonal moisture triggered strong storms over the West. A trough of low pressure over the western Gulf of Mexico pushed more moisture onshore. This brought more showers and thunderstorms to eastern Texas and the Lower Mississippi River Valley. Flooding remained of concern since some areas saw another 2 to 4 inches of rain. Heaviest rainfall was reported in Beaumont, Texas with a mid-day total of 3.96 inches of rain. Just north of this activity, a frontal boundary lifted northward through the Eastern Valleys. This pushes warm and humid air northward, which created favorable conditions for thunderstorm development. These storms have not turned severe but areas of heavy rainfall developed. Heaviest rainfall was reported in Clemson, South Carolina with a mid-day total of 2.10 inches of rain. In the Midwest, a cold front produced scattered storms as it advanced eastward from the Upper Midwest and into the Great Lakes. Some storms turned severe along the front with strong winds and hail. Wind gusts up to 60 mph were reported in Marshall, Kansas. Meanwhile, out West, monsoonal moisture brought thunderstorm activity to the Southwest, Great Basin, and Intermountain West. These storms were capable of producing strong winds and periods of heavy rainfall, but severe storms have not yet developed.

 

15^th-21^st…Somewhat limited precipitation fell in the country on Monday as somewhat weak storms moved through the country. The strongest of these storms began the day over the Dakotas before moving into northern Minnesota. This storm did not carry much moisture, thus only a few showers and thunderstorms developed in the region. Meanwhile, a weak storm moved through New England and into the Atlantic Ocean. This storm produced early morning showers from New Jersey through Maine before moving out into open water. A high pressure system stretched across the Southeast and continued to produce mostly dry conditions. One exception to this was in Florida where some thunderstorms moved over the state. Afternoon thunderstorms also developed in the Southern Plains and Lower Mississippi Valley. In the West, monsoon moisture continued to creep into the Southwest, instigating scattered showers and thunderstorms that are fairly normal for this time of year. This monsoon streamed northward into the Great Basin and Intermountain West. The Northeast rose into the 80s and 90s, while the Southeast saw temperatures in the 90s. The Southwest rose into the 90s and 100s, while the Northwest saw temperatures in the 60s and 70s. The Northern Plains were particularly hot with temperatures into the triple digits.

Hot, humid, and unsettled weather continued in the East on Wednesday. Scattered showers and thunderstorms developed along a frontal system extending from the Upper Midwest through the Ohio River Valley and ahead of a cold front extending through New England and the Lower Great Lakes. As of this afternoon, there have been numerous quarter to ping pong ball sized hail (1.00 to 1.50 inches in diameter) and high wind reports with downed trees and wires in these regions. South of this front, hot temperatures persisted for the Midwest into the Eastern Valleys. An Excessive Heat Warning remains in effect for these areas as highs reached into the lower 100s for many areas. Further south, warm and moist air supported thunderstorm development across the Southeast and Gulf States.

In the West, moist flow from Post-Tropical Cyclone Fabio, located at about 425 miles southwest of Punta Baja Mexico, produced scattered showers off the coast of southern California. Meanwhile, a trough of low pressure in the Pacific Northwest maintained chances of showers for the Pacific Northwest and northern California.

The central U.S. saw another hot day on Friday, while showers and thunderstorms continued in the East. A ridge of high pressure stretched from the Plains through the mid-Mississippi River Valle and created another hot and dry day. Excessive heat warnings remained in effect in these areas as high temperatures reached into the lower 100s again. These conditions are about 10 degrees above seasonable. In the East, a cold front lingered over the Eastern Valleys, and slowly moved southward throughout the day. Moisture from the Gulf of Mexico fed energy into this system, which kicked up showers and thunderstorms from the Gulf coast through the Northeast. There was a slight chance of severe weather development, but severe storms have not yet been reported. Heaviest rainfall developed across the Lower Mississippi River Valley with a mid-day total of 2.08 inches reported in New Orleans, Louisiana. To the west, a cold front moved through the Northern Plains and into the Upper Midwest. This produced showers and thunderstorms throughout the day, but significant storms and heavy rainfall has not developed. Behind this system, a trough of low pressure over the Pacific Northwest pulled moisture onshore, and brought moderate to heavy showers and thunderstorms to the Pacific Northwest through Montana.

Two cold fronts brought more thunderstorm activity to the eastern U.S. on Friday. One front extended from the Northeast and into the Gulf of Mexico, which created widespread showers and thunderstorms. Some of these storms turned severe with heavy rainfall and strong winds. Heaviest rainfall was reported in Alpine, Texas with a mid-day total of 2.61 inches of rain. Behind this system, another front moved over the Upper Midwest and Great Lakes, into the Midwest. This system also created showers and thunderstorms throughout the day, some of which also turned severe. There have been multiple reports of large hail from Michigan, while wind gusts up to 60 mph were reported in Fishers, Indiana. Behind this activity in the Plains, a ridge of high pressure covered the Central and Northern Plains. This pushed moisture away to the south, and allowed for sunny skies and warm temperatures to continue. Heat advisories have been issued across the region as highs approached 100 degrees in some places. Out West, monsoonal moisture over the Four Corners advanced northward over the Rocky Mountains. This system produced showers and thunderstorms that extended from Arizona and New Mexico, into Idaho and Montana. Severe thunderstorms and heavy rainfall did not develop in these areas. Meanwhile, a trough of low pressure moved over the Pacific Northwest and pushed cloudy skies and cooler temperatures inland.

 

29^th-31^st…An active weather pattern developed across the nation on Monday as monsoonal activity continued in the West, a frontal system dropped into the Upper Midwest, and a trough of low pressure lingered over the eastern third of the nation. In the West, a plume of subtropical moisture from the Pacific Ocean streamed inland from the southwest across southeastern California and the Four Corners through the day. Ample moisture over these areas combined with waves of energy pushing through the region translated into heightened monsoonal activity during the afternoon with areas of rain and thunderstorms. Flash Flood Watches remained in effect for areas from southeastern California and northwestern Arizona through southern Utah, while a Flash Flooding became possible for parts of the south-central Mohave County in northwestern Arizona. To the east of this activity, high pressure ridging continued over the south-central U.S. with scorching hot temperatures. Areas from the Southern Plains and the Lower Mississippi Valley northward into the Central Plains and the Mississippi Valley experienced daytime highs ranging from 100 to 110 degrees. A few showers and thunderstorms formed in the Mid-Mississippi Valley as disturbances from the West were guided through the Central Plains, but provided little relief from the heat. A variety of Heat Advisories and Excessive Heat Warnings remained in effect for the region.

To the north, a frontal system continued to drop into the Upper Midwest with chances of showers, thunderstorm, and a slight risk of severe wind and hail. In the East, a trough of low pressure lingered over the eastern third of the nation and supported more showers and thunderstorms from portions of the Mid-Atlantic through Southeast. Much of this weather activity was focused near a frontal boundary that stalled from the North Carolina coast through the Southeast and across northern Florida. Parts of the Mid-South through and areas from the northern Gulf Coast to southern Georgia and South Carolina remained at slight risk of severe thunderstorms with severe wind and hail.

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