NATIONAL WEATHER SUMMARY
SEPTEMBER 2010
1st-4th…Hurricane
Earl continued to reduce in strength on Friday as it tracked northeastward up
the East Coast. The system moved about 175 miles northeast of Cape Hatteras
North Carolina and currently located about 350 miles south-southwest of
Nantucket, Massachusetts. The system reduced to a category 1 storm with maximum
winds at 85 mph as it moved north-northeastward at 21 mph. The system brought
heavy rains, strong winds, and dangerous surf to the East Coast from the
Carolinas to Maine. Manteo, North Carolina reported 3.92 inches of rain with
wind gusts up to 70 mph. Rainfall totals along the coasts of the Mid-Atlantic
states ranged from 1-3 inches, while the coasts of New England saw increasingly
windy conditions and cloudy skies. Behind this system, Tropical Storm Fiona,
located about 245 miles south-southwest of Bermuda, continued to track
north-northeastward at 13 mph. The system remained at tropical storm strength
with maximum winds at 35 mph as it moved further away from the East Coast.
Elsewhere in the US, a low pressure system in Canada pushed a cold front from
the Midwest and into the East Coast. This kicked up more scattered showers and
thunderstorms. High pressure quickly built in behind it and brought sunny skies
and mild weather to the Plains. The West Coast also saw mild weather due to a
dominating ridge of high pressure. A trough of low pressure approached British
Colombia and the Pacific Northwest, but only bought a few clouds.
5th-11th…Tropical
Storm Hermine was located about 85 miles east-northeast of La Pesca, Mexico and
about 140 miles south-southeast of Brownsville, Texas on Labor Day. It
continued decreasing in strength with maximum sustained winds at 60 mph and
moved north-northwest at 14 mph. This system has already kicked up scattered
showers and thunderstorms over eastern Texas and northeastern Mexico. Rainfall
totals reached 0.80 inches in Port Isabel, Texas, while 44 mph wind gusts were
reported in Lufkin, Texas. Also in the South, a stationary front lingered over
Florida and kicked up scattered showers and thunderstorms. Storms associated
with this front have not yet turned severe but 0.61 inches of rain fell over
Okeechobee, Florida. Elsewhere, a low pressure system in the North developed as
it moved off the Northern Rockies and into the Northern Plains. This system
pushed a frontal boundary through Upper Midwest, which triggered scattered
showers and thunderstorms throughout the day. Some of these storms turned severe
with large hail stones up to 1 inch in diameter in Milwaukee, Wisconsin.
Rainfall totals ranged from a half of an inch to an inch, with 1.17 inches
reported in Mobridge, South Dakota. This slow-moving storm caused minor flooding
problems across the Dakotas and Minnesota. To the East, a ridge of high pressure
dominated the weather over the Northeast, New England, and Mid-Atlantic states.
This allowed for sunny skies, warm temperatures, and highs in the 70s and 80s.
The West Coast remained under pleasant weather conditions with sunny skies.
however, a trough of low pressure dipped into the PAcific Northwest, and kicked
up scattered clouds but precipitation has not yet been triggered.
Tropical Storm Hermine made landfall on the coast of northeast Mexico late
Monday night with heavy rainfall and sustained tropical storm force to near
hurricane force winds and gusts. The highest wind reported in the United States
was 55 mph with a gust to 65 to 70 mph at Valley International Airport in
Harlingen, Texas early Tuesday morning. Since landfall, Hermine had begun
weakening and moved northward through the Rio Grande Valley Tuesday morning.
Moderate to heavy rainfall fell across exas. Rainfall accumulations had reached
4 to 8 inches. Farther north, a large low pressure system over the Upper Midwest
moved eastward into the Great Lakes region Tuesday, with its cold front extended
across the Ohio Valley and Mississippi Valley. The main threat for this system
was the heavy rain band along the southern portion of the cold front that cut
across southern Missouri, northern Arkansas and eastern Oklahoma. Otherwise,
mainly scattered showers and isolated thunderstorms developed near the center of
the low pressure from Minnesota to the Upper Peninsula of Michigan and along the
northern portion of the front. Elsewhere, a weak front that moved ashore late
Monday night and early Tuesday, produced light to moderate rain over parts of
the Northwest. In addition, a weak stationary front in the Southwest supported
scattered showers and isolated thunderstorms in southern Nevada, northern
Arizona and southern Utah. In the Southeast, numerous moderate to heavy showers
and thunderstorms continued to affect most of the Florida Peninsula Tuesday,
especially across the interior and western part of the peninsula.
The
remnants of Tropical Depression Hermine continued to bring flooding rains from
central Texas to northern Oklahoma on Wednesday. The storm dumped an estimated
10 to 15 inches of rain over the past 24 hours and led to serious, life
threatening flash flooding concerns across the central and northern portions of
eastern Texas. In the storm total rainfall report through 10 a.m. CDT,
Georgetown Texas reported 13.20 inches, while Austin, Texas reported 11.48
inches. Along with heavy downpours, strong to damaging wind gusts were reported
through the afternoon. Elsewhere, in the East, a broad low pressure system over
Quebec, Canada brought increased cloud coverage and windy conditions to portions
of the Great Lakes and the Northeast. A warm front associated with the low
lifted across Maine with scattered rain showers through the afternoon.
Meanwhile, showers developed along and ahead of an associated cold front that
extended through New England, the Mid-Atlantic, and the Tennessee Valley. Behind
the cold front, cooler air settled over the Great Lakes and the Northeast and
yielded to lower daytime highs. A few showers also developed downwind of the
Lower Great Lakes. In the West, a low pressure trough produced scattered light
to moderate showers from areas of northern California through Washington as the
system lingered over the Pacific Northwest. Elsewhere, disturbances rippling
through the moist southwest flow spreading across the Four Corners produced more
scattered showers and thunderstorms in the Central and Southern Rockies.
A cold
front kicked up scattered showers and thunderstorms through the Central part of
the nation, while the remnants of Tropical Storm Hermine moved through the South
on Friday. A low pressure system skirting across the Canadian and U.S. border
pushed a cold front through the Northern Plains and Upper Midwest, which
extended into the Central Plains. This front kicked up scattered showers with
heaviest rainfall in the North. These storms have not yet turned severe, but
have triggered rainfall amounts between 2-3 inches. Metropolis, Illinois
reported 3.15 inches of rain, while Warroad, Minnesota saw 1.36 inches of rain.
As this front moved through, it dropped temperatures by about ten degrees from
the mid- to upper 70s, to mid- to upper 60s. Meanwhile, in the South, the
remnants of Tropical Storm Hermine continued moving northeastward from the Lower
Mississippi River Valley up the Tennessee River Valley. The system has lost most
of its strength, but continued to kick up periods of isolated heavy rains.
Poplar Bluff, Missouri reported 3.68 inches of rain, while 3.28 inches were
reported in Paducah, Kentucky. As the system was closely followed by the cold
front, floods threatened the Mid- and Lower Mississippi River Valley. In the
West, high pressure dominated the West Coast to the Rockies. Sunny skies and hot
temperatures persisted, but winds significantly reduce over the Rockies. Thus,
the wildfires west of Boulder, Colorado became more manageable and fire
authorities ended the evacuations and road blocks.
19-25th…The
nation saw relatively mild weather on Monday as a ridge of high pressure
dominated much of the nation. A ridge built from the Plains, over the
Mississippi River Valley, and stretched to the East Coast. This allowed for
sunny skies, warm temperatures, and pleasant conditions over the Eastern half of
the country. The Northeast saw highs in the 60s, while New England reached into
the 70s, both with plenty of sunshine. The Southeast and Mid-Atlantic states saw
another hot day with highs in the 90s. Cloudy skies moved into the Northern
Plains and Upper Midwest on Monday. These clouds developed along a warm front
that was produced by a low pressure system moving in from the Northern Rockies.
This system kicked up overcast skies, but light and scattered showers were
contained to the Northern Rockies. Rainfall totals were lass than a half of an
inch in most areas, with up to 0.65 inches reported in Havre, Montana. To the
South, ample moisture pushed into southeastern Texas from the Gulf of Mexico.
Due to warm conditions inland, this produced scattered showers and
thunderstorms. Corpus Christi, Texas reported 1.61 inches of rain and wind gusts
up to 27 mph. Out West, clouds lingered over the Pacific Northwest as a trough
of low pressure slowly moved eastward throughout the day. California and the
Southwest saw mostly sunny skies as higher pressure dominated. The deserts
reached highs above 100 degrees.
Scattered showers and thunderstorms developed over the center of the nation on
Wednesday. A low pressure system slowly moved off the Central Rockies and pushed
a warm front through the Central and Northern Plains, which stretched into the
Upper Midwest. Meanwhile, a cold front from a low pressure system in eastern
Canada hovered over the Northeast and New England. Strong flow from the South
pulled in abundant moisture from the Gulf of Mexico, thus scattered showers and
thunderstorms developed. Rainfall totals ranged between 1-2 inches along the
front, with multiple reports of severe weather development. Quarter to golf ball
size hail covered the ground in Atkinson, Nebraska, while 3.5 inch diameter hail
was reported 1 mile north of Vermillion, South Dakota. Heaviest rains fell over
Kaiser, Missouri with a mid-day total of 2.00 inches. The eastern end of this
system produced hail from nickel to quarter size with damaging winds in Newport,
Virginia. In the West, Tropical Depression Georgette moved into the northern
Gulf of California. Flow around this system pulled moisture over northwestern
Mexico and into the Southwestern US. This brought cloudy skies which triggered
scattered showers and thunderstorms over the region. Flagstaff, Arizona reported
0.44 inches of rain, while Farmington, New Mexico saw 0.37 inches of rain.
Elsewhere, the rest of the West Coast saw warm and dry conditions with sunny
skies as high pressure prevailed.
Scattered showers persisted over the central U.S. on Friday. A low pressure
system continued tracking eastward over the Great Lakes and Midwest. The system
produced a strong frontal boundary. A warm front lead the system into the
Northeast, while a cold front extended southward over the Mississippi River
Valley. The cold front kicked up another 1-2 inches of rain, thus, flooding
remained a concern over the upper and Mid-Mississippi River Valley. The warm
front in the East also brought periods of heavy rainfall with reports of 0.76
inches in Saranac Lake, New York. Severe weather has not yet been reported in
associated with these systems. Behind this cold front, temperatures dropped
significantly. The Upper Midwest and Northern Plains saw highs in the 50s, while
the Mid-Mississippi remained in the 60s and 70s. The tail end of the front
stretched into Texas, where it obtained additional moisture from the Gulf of
Mexico. The region saw scattered showers with 1.21 inches reported in Wichita
Falls, Texas. South of the system, the rest of the East Coast saw mild weather
as high pressure dominated. This brought sunny skies and warm temperatures with
highs in the 90s. Out West, high pressure also dominated the West Coast. This
acted to keep moisture offshore and allowed for plenty of sunshine. A heat wave
hit California as highs reached into the 90s in many regions, with near 100
degrees reported across the deserts of the Southwest.
26th-30th…Much
of the nation experienced little change in weather activity on Monday. In the
East, active weather covered much of the Eastern Seaboard as a low pressure
trough hung over the eastern third of the nation. A steady surge of moisture
associated with the trough combined with frontal boundaries that stretched from
the southern New England through the Florida Panhandle and into the Gulf of
Mexico to produce more scattered showers with embedded thunderstorms, bands of
heavy rainfall, and strong wind gusts. Persistent showers and periodic heavy
rainfall created chances of local flooding throughout the day. Increased
instability over these regions also created chances of severe storms with
possible tornadoes from portions of Georgia and South Carolina into the Delmarva
region. In the Midwest, a cold front moved through the eastern Dakotas and
northwestern Minnesota with showers and thunderstorms. Cool and gusty northwest
winds accompanied the front and lead to cooler daytime highs in the area. In the
West, subtropical moisture triggered more light, scattered showers and patchy
drizzle along the Pacific Northwest Coast. The rest of the West remained
unseasonably hot and dry due to a lingering strong ridge of high pressure. The
combination of very hot temperatures, very low relative humidity levels, gusty
northeast winds and critically dry fuels produced critical fire weather
conditions across the Mountains of Ventura and Los Angeles Counties, the Santa
Clarita Valley, and the Ventura County Valleys. Fire weather conditions also
developed in northeastern Colorado, southeastern Wyoming, and western Nebraska.
Much
of the Eastern Seaboard continued to experience wet and stormy weather on
Wednesday due to Tropical Storm Nicole, located 80 miles northeast of Havana
Cuba, and an elongated trough of low pressure over the region. The circulation
of Tropical Storm Nicole became poorly defined through the afternoon as it
trekked toward the north-northeast near 10 mph with maximum sustained winds near
40 mph. While, heavy thunderstorms over eastern Florida, the western Bahamas,
and the Caribbean remained poorly organized, rain accumulations of 4 to 8 inches
were possible over portions of southern Florida, the Florida Keys, and the
central and northwest Bahamas. These rains created chances life-threatening
flash floods. In addition to strong winds and significant rainfall, isolated
tornadoes were also possible along the immediate coast of southeastern Florida
and the Florida Keys. Meanwhile, a steady stream of tropical moisture surging up
the East Coast combined with a frontal boundary over the Mid-Atlantic and fueled
widely scattered showers, locally heavy rainfall, and thunderstorms from the
nearby coastal areas of the Carolinas to New Jersey during the afternoon. Behind
the active weather of the East, a strong ridge of high pressure continued to
bake the West with above normal temperatures. While areas along the West Coast
experienced the start of a cooling trend today, daytime highs remained
unseasonably warm.
The historic rainfall continued along the eastern
seaboard Thursday as a low pressure system and its associated front moved slowly
northward. Over 8 inches of rain fell just on Thursday for parts of North
Carolina through Maryland, while rainfall estimates of 1 to 2 inches were common
into parts of New England. This tremendous amount of rain prompted Flood Watches
or Warnings from northern South Carolina through Maine as many rivers in the
region were above 90% of their flood stages. To make matters worse, the storm
was strong enough to instigate High Wind Warnings in New England as wind gusts
were expected to increase to 40 to 50 mph later Thursday and into Friday.
Tornado Watches were also posted late in the afternoon for parts of
Pennsylvania, Maryland, and Delaware to wrap up the active weather in the south.
Low relative humidity combined with strong wind in the Southeast to produce
dangerous fire weather and Red Flag Warnings in Mississippi and Alabama. In the
West, dry lightning in Southern California prompted fire weather worries and Red
Flag Warnings as well. Residents in the area should be very careful and clear
brush away from houses that in the hills. The Northeast rose into the 60s and
70s, while the Southeast saw temperatures in the 70s and 80s. The Northwest rose
into the 60s and 70s, while the Southwest saw temperatures in the 80s, 90s, and
100s.
Jim G. Munley, jr.
http://www.jimmunleywx.com
