MAY 2012


1st-5thA arm front lifted through the Upper Great Lakes and the Upper Mid-Atlantic during the afternoon, while a second associated front remained nearly stationary from the Upper Mississippi Valley through the Central Plains. Showers and thunderstorms were anticipated between these frontal boundaries and ahead of the warm front, from the Midwest eastward through the Great Lakes, Ohio Valley, Mid-Atlantic and parts of Lower New England. Elsewhere, showers, bands of heavy rain, and thunderstorms developed over southeastern Louisiana and extreme southwestern Alabama.

In the West, a few areas of light rain formed in the Northwest, while a stationary front extending through the Central Great Basin aided in producing scattered rain showers and possible thunderstorms in the high country of Colorado during the afternoon. Further south, Red Flag Warnings persisted across much of New Mexico into western Texas. Poor, single digit humidity levels, well above normal daytime highs, strong instability, and slightly higher wind speeds than yesterday created critical fire weather conditions across the region through the afternoon.


6th-12thA complex storm system moved through the middle portion of the country on Monday, instigating another round of scattered showers and thunderstorms. A cold front moved through the Plains, ushering moist Gulf of Mexico air northward into the Mississippi Valley. This moisture produced severe thunderstorms that rolled through Missouri and Arkansas. There were no reports of tornadoes halfway through the afternoon, but tornadoes will be possible into the evening. Residents in the Mississippi Valley and Ohio Valley should monitor the progress of any thunderstorm in their area and be prepared to take any precautions necessary to protect life and property. Elsewhere, strong thunderstorms moved through the Ohio Valley and southern Michigan in the morning, but greatly diminished by the afternoon. Elsewhere, a weak storm moved through the Great Basin and into the Rockies by the afternoon. This storm lacked significant moisture, but did produce some showers in Colorado in the afternoon.

Along the West Coast, a high pressure system provided dry conditions while also warming temperatures. Areas in the Southwest and Southern California could expect to experience triple digit temperatures in the afternoon. The Southeast rose into the 70s and 80s, while the Northeast saw temperatures in the 60s and 70s. The Southern Plains rose into the 80s and 90s, while the Northwest saw temperatures in the 60s and 70s.

Heavy rains developed along the East Coast on Wednesday, as a cold front extended from Maine through the Gulf of Mexico. A low pressure system that moved over the Great Lakes and into the Northeast pushed a cold front eastward from the Eastern Valleys. Moisture poured in ahead of this front from both the Gulf of Mexico and Atlantic Ocean, which kicked up heavy rainfall and strong thunderstorms. Mid-day rainfall totals have surpassed 2 inches in parts of Connecticut and Rhode Island. Strong winds blew large trees down and a tin roof was torn off a building in Aiken, South Carolina. Behind this system, in the Plains a ridge of high pressure built over the Central US and created another warm and dry day. However to the south, a trough of low pressure developed over New Mexico and western Texas. This system pulled moisture in from the Gulf of Mexico and produced periods of heavy rain throughout the day. In the West, high pressure covered most of the West Coast and allowed for warm and dry conditions to continue. In the Pacific Northwest, a cold front dipped in from British Columbia and brought windy conditions and a few scattered showers to the region.

Shower and thunderstorm activity persisted for the Plains, while the East and West Coasts remained dry on Friday. A strong low pressure system lingered over Texas and pulled more moisture and energy in from the Gulf of Mexico. This produced more heavy rains and strong thunderstorms across Texas and Oklahoma. Some of these storms turned severe with strong winds, large hail, even a few tornadoes. Mid-day rainfall totals reached over 2 inches across the region, with the heaviest rainfall reported in Houston, Texas with a mid-day total of 2.56 inches. A tornado was reported on South Padre Island, Texas. Elsewhere, a low pressure system over central Canada pushed a cold front through the central US. This frontal boundary stretched southwestward from the Great Lakes, over the Plains, and into the Four Corners. This kicked up lighter and more widespread showers and thunderstorms than the storms over the Southern Plains. These storms have not turned severe and significant rainfall was not reported with this system. Meanwhile, high pressure dominated the East and West Coasts on Friday. This allowed for a warming trend to persist for both the Eastern and Western US. Highs ranged in the 90s over the deserts of the Southwest, while highs ranged in the 80s and 90s across the Southeast.


13th-19thA relatively mild and inactive day greeted the country today as only a few areas of rain developed. The strongest storm in the country moved through the Southeast and streamed some moisture into the Southeast and Mid-Atlantic. This moisture produced rain from the Carolinas through parts of the Northeast, but was not widespread in nature. Thunderstorms in the Carolinas were strong enough to produce strong, damaging winds along with at least one report of a tornado along the border of North Carolina and South Carolina. Meanwhile, more scattered thunderstorms pressed through western Texas. Even though these thunderstorms had not produced large hail or tornadoes by the afternoon, their associated rain prompted Flash Flood Watches in the state. This means these thunderstorms were capable of producing minor flooding in streams and streets. Also, a weak low pressure system along the West Coast provided a brief cooling trend in California along with a few areas of drizzle. This cooling trend did not reach the Southwest the temperatures once again rose into the 90s and 100s. The Northeast rose into the 70s, while the Southeast saw temperatures in the 70s and 80s. The Northern Plains rose into the 70s and 80s, while the Northwest saw temperatures in the 70s and 80s.

Unsettled weather continued in the Eastern U.S. on Wednesday as a long cold front dropped across the Midwest and reached from the Lower Great Lakes through the Southern Plains during the afternoon. Moist and unstable conditions ahead of the northern edge of this cold front led to scattered showers. Meanwhile, to the south, scattered thunderstorms popped up again along the sea breeze of the Carolinas. Plenty of moisture streaming across the area heightened instability and led to the possibility of few intense storms with hail and gusty to damaging winds.


Further south, weak winds and a lingering moist air mass allowed showers and thunderstorms to persist across parts of the Florida Peninsula through the afternoon. In the West, well above average temperatures continued in the Desert Southwest, while a few isolated showers developed in the Central Great Basin.

Showers and thunderstorms developed over the Northern and Central Rockies on Friday as a low pressure system slowly moved off the Rockies into the Plains. Some of these storms turned severe in parts of Utah and western Colorado with strong winds and large hail. Limited moisture associated with this system allowed for rainfall totals to remain less than an inch for most areas. Winds up to 61 mph were reported at Bluffdale, Utah. A cold front extended south of this system and produced strong winds across the Great Basin and Southwestern US. In combination with hot temperatures and low relative humidity, this kept fire danger high for Arizona, New Mexico, and into the Central Rockies. Meanwhile, a warm front extended eastward from this system, and produced scattered showers over the Dakotas. Heavy rainfall has not been reported and severe thunderstorm development was not anticipated across the Northern Plains. In the East, a ridge of high pressure created a warm, dry, and pleasant day for most of the Eastern US as it covered from the Northeast through the Eastern Valleys. High temperatures ranged in the 70s across the Northeast and Mid-Atlantic states, while parts of the Midwest reached into the 80s. In the Southeast, the tail end of a cold front lingered over the Carolinas and Florida, which triggered more showers and thunderstorms throughout the day.

Unsettled weather formed across the Northwest and upper Midwest on Wednesday as a trough of low pressure settled over the Northwest. Moisture streaming across the region continued to support areas of light to moderate rain showers from the Pacific Northwest through the Northern Rockies with chances of snow in the higher elevations of the Northern Rockies. Meanwhile, a cold front from the West moved across the upper Midwest, Central Plains, and Central High Plains this afternoon and brought rain and thunderstorms to areas of Minnesota and the Dakotas. In the Southwest, fire weather danger remained high across the Southwest as above normal temperatures, single digit relative humidity levels, and windy weather conditions persisted in many areas. In the East, a few showers continued across the Northeast and the Mid-Atlantic during the afternoon as a frontal system lingered across the Eastern Seaboard. Meanwhile, heavy rain and strong thunderstorms with gusty winds persisted across the southern tip of Florida. Saturated grounds from the heavy rainfall that occurred yesterday combined with today's rainfall resulted in Flood Watches in Miami-Dade County. Additional rainfall accumulations were expected to range from 1 to 2 inches through tonight with locally higher amounts possible in more concentrated bands of rain.

Scattered thunderstorms persisted over the central U.S. on Friday, as a frontal boundary draped from the Midwest through the Rockies. This was a result of two areas of low pressure. One system moved over the Upper Midwest and into eastern Canada, while another moved eastward from the Central Rockies. This allowed for a frontal boundary to extend from the Great Lakes, over the mid-Mississippi River Valley, and into the central Plains. Scattered showers and thunderstorms developed along this frontal boundary. Some of these storms turned severe over Iowa and Nebraska with strong winds and large hail. Rainfall totals ranged from 1 to 2 inches across the central U.S., with heaviest rainfall reported in Olathe, Kansas with a mid-day total of 2.13 inches of rain. Behind this system, a low pressure system moved over northern California and into the Great Basin. This brought scattered rain showers to the Pacific Northwest, parts of northern California, and into the Intermountain West and Great Basin. Highest elevations saw overnight and early morning snow showers due to cool temperatures associated with this air mass. The southern side of this system created strong winds for the Southwest and Southern Rockies. Due to prevailing warm and dry conditions, fire danger remained high for these areas.

Tropical Storm Beryl made landfall very early Monday morning near Jacksonville Beach, Florida with sustained winds just below hurricane strength. The storm caused only minor flooding and damage, mostly associated with downed trees and power lines. Beryl knocked out power to nearly 30,000 residents and tore the roof off of at least one house.

The biggest effect from Beryl was the rain it produced. Several inches of rain fell north of Tampa Bay, with the wettest areas receiving over 4 inches of rain. This may be potentially good news for northern Florida and adjacent areas of Georgia as the region has been suffering through an exception drought. Meanwhile, a cold front move through the Plains and Upper Midwest. A heat wave continued in the Southeast and Ohio valley as temperatures once again rose into the 90s. The Southern Plains and Southeast rose into the 80s and 90s, while the Northeast saw temperatures in the 70s and 80s. The coolest area of the country was Montana and North Dakota as afternoon temperatures were only in the 40s. The Northwest into the 60s and 70s.

Jim G. Munley, jr.

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