06-22-2008, 05:39 AM
WEATHER HAZARDS (During The Next 24 Hours)
SEVERE WEATHER OUTLOOK
(potential for tornadoes, damaging winds, and large hail within the next 24 hours)
SCATTERED Severe Thunderstorms
(Large Hail, Microbursts)
BC....AB
Some Thunderstorms May APPROACH Severe Limits
MT....ID....UT....N AZ....NM....CO....WY
Some Thunderstorms May APPROACH Severe Limits
OK....TX....LA....MS....AL....FL....GA....SC....NC....VA....WV....OH....KY....IN....IL
WI....MI....ON....QC
ISOLATED Severe Thunderstorms
(Microbursts, Large Hail)
DC....MD....DE....PA....NJ....NY....CT....RI....MA....VT....NH....ME
HEAVY RAINFALL OUTLOOK
(potential for an inch or more total rainfall within the next 24 hours)
Isolated Locations In
DC....MD....DE....PA....NJ....NY....CT....RI....MA....VT....NH....ME
(QPF 1 - 3")
Isolated Locations In
OK....TX....LA....MS....AL....FL....GA....SC....NC....VA....WV....OH....KY....IN....IL
WI....MI....ON....QC
(QPF 1 - 2")
Scattered Locations In
BC....AB
(QPF 1 - 3")
Isolated Locations In
MT....ID....UT....N AZ....NM....CO....WY
(QPF 1 - 2")
EXCESSIVE HEAT OUTLOOK
(potential for maximum temperature to exceed 95 deg F within the next 24 hours)
NUMEROUS Locations In
CA....AZ....NV....S UT....S MT....WY....CO....NM....TX....OK.....W, C KS....W NE
W SD
TROPICAL WEATHER SUMMARY
(review of disturbances over the Atlantic Basin and Eastern Equatorial Pacific Ocean)
The character of ENSO in the equatorial Pacific Ocean has shifted to a neutral (3,4) and El Nino (1,2) signature in the oceanic sectors responsible for designating events. Current rate of warming of SSTs points toward a weak El Nino in place by August 1. Such a signal would indicate reduction of the window for hurricane formation from ITCZ waves originating in western Africa.
Other hydrothermal anomalies worth noting:
Warming of waters off of the West Coast. This signifies increased potential for strong ridging along and west of the Continental Divide. By later summer, this may result in a more westward orientation of hot temperatures.
Water temperatures across the entire western Atlantic Basin are normal or above average, which are favorable for tropical cyclone development and intensification.
Eastern Equatorial Pacific Ocean: Three ITCZ impulses from below Panama to well south of Baja California. Some organization is possible for the disturbance closest to Central America.
Atlantic Basin: Well-developed tropical wave about 800 miles east-southeast of Windward Islands. Strengthening is unlikely due to infiltration of dust and hot, dry air in its northern quadrants and the presence of shearing southwest flow aloft to the northwest of this system.
African ITCZ: Saharan heat ridge is limiting thunderstorm formation over the Sahel. Four strong convective circulations moving westward pose no immediate risk of tropical cyclone formation.
The Orient: Weakening Typhoon Fengshen is now passing through Luzon island. Fengshen may become a tropical storm or depression before re-intensification begins over the South China Sea. Later, this feature may strike or pass very close to Taiwan as a Category 1 typhoon. Also watch for a disturbance to the right of Fengshen, which may track northward toward Japan in an environment favorable to strengthening.
SHORT RANGE OUTLOOK
(Through The Next 72 Hours)
"High Humidity And Scattered Thunderstorms"
As can be seen in the attached QPH chart for Sunday, June 22, scattered showers and thunderstorms will be the dominant condition over much of the U.S. A weak 500MB trough over the Great Lakes and Ohio Valley will stimulate convection in Appalachia and the Eastern Seaboard, with some of the storms nearing or surpassing severe limits. Across the otherwise hot West, diurnal and orographic cumulonimbi will bring pockets of heavy rainfall, microbursts, and hail through the next few days.
Extreme Heat Rules Most Of Western Half Of The U.S.
Those who are lucky enough to be near a thunderstorm in the western states (or along the coastline of Oregon and Washington) may at least dodge two or three hours of intense heat. The powerful Sonoran heat ridge is beginning to flex toward the north and east, which in turn should bring some of the torrid values into the Great Plains. The Midwest and Northeast, meanwhile, with "leftover" or "stale" cooler air from Canada, may dodge the heat bullet until next Wednesday or Thursday.
MEDIUM RANGE OUTLOOK
(Four To Ten Days From Now)
Two Heat Ridges For The Price Of One
It is bad enough when one heat ridge affects the U.S. But an ongoing theme through the 6-10 and 11-15 day time frames is the presence of TWO subtropical highs, one of the Sonoran type and another in the Southeast (Great Smokies variety). Essentially, this creates a hot West and South, cooler Great Lakes and Northeast temperature pattern. But with every shortwave passing along the Canadian border, some of the high heat will find its way into major cities such as Minneapolis MN, Chicago IL, Cleveland OH, and New York NY.
Weakness Adds High Humidity Over Eastern Half Of Nation
The position of a weakness between the two heat ridge complexes (Sonoran and Great Smokies) will allow a stream of high dewpoints from the Gulf of Mexico to reach across most of the eastern half of the U.S. during the medium range and extended outlook. With available moisture and plentiful upper level dynamics in play, numerous diurnal thunderstorms can be expected to the right of the Mississippi River. The biggest issue, however, will be the unrelenting high humidity affecting energy consumers.
Severe Thunderstorms Shift Toward The Canadian Border
The numerical models and the respective ensemble forecasts have shown an impressive ridge building pattern, with much of the lower 48 states involved with heat ridge development through the next two weeks. By Day 10, the mean jet stream position should be parallel to and slightly above the Canadian border. That configuration almost always favors the best chance for thunderstorms, and with severe weather, running through the northern tier states.
EXTENDED PERIOD FORECAST
(Between Day 11 And Day 15)
Are We Locked Into A Pattern That Will Last For Much Of The Summer?
Since the same signals and signatures keep appearing on the various model forecasts (no, not the infamous "indices" which show no strong pattern identification of any kind....), it would appear that the weather evolving in the past two weeks will be a "keeper" for much of the summer. There has been a distinct shift in computer outlooks toward a massive western (+PNA) ridge complex, with a smaller Great Smokies heat ridge. If so, this will likely be a brutal summer in the West and in the Old South, with the Great Lake and Northeast in the normal to below average temperature realm. The threat for severe thunderstorms that has dominated the Midwest in the spring will very likely shift above Interstate 80 and to the right of Interstate 35 during the following 2 to 3 months.
Tropical Cyclone Chances May Be Increasing By Mid-July
There is a very subtle shift to lesser upper level shear in computer forecasts for the 11-5 day time period. Up until this time, we have seen two limiting factors for tropical cyclone development: a high volume of hot, dry, dusty air advected from the Saharan heat ridge and strong, shearing southwest flow aloft across much of the Atlantic Basin. The ITCZ has been quite active with multiple, intense impulses. With water temperature rises noted between western Africa and the Americas, I suspect that there will be a two month window (say July 15 to September 15) for important warm-core cyclogenesis. After that point, the budding El Nino episode will very likely exert a hostile vertical environment for tropical convection.
Prepared by Meteorologist LARRY COSGROVE on
Saturday, June 21, 2008 at 6:45 P.M. CT
Disclaimer:
The previous statements are my opinions only, and should not be construed as definitive fact. Links provided on this newsletter are not affiliated with WEATHERAmerica and the publisher is not responsible for content posted or associated with those sites.
Copyright 2008 by Larry Cosgrove
All rights reserved.
This publication may not be reproduced or redistributed in whole or in part without the expressed written consent of the author.
SEVERE WEATHER OUTLOOK
(potential for tornadoes, damaging winds, and large hail within the next 24 hours)
SCATTERED Severe Thunderstorms
(Large Hail, Microbursts)
BC....AB
Some Thunderstorms May APPROACH Severe Limits
MT....ID....UT....N AZ....NM....CO....WY
Some Thunderstorms May APPROACH Severe Limits
OK....TX....LA....MS....AL....FL....GA....SC....NC....VA....WV....OH....KY....IN....IL
WI....MI....ON....QC
ISOLATED Severe Thunderstorms
(Microbursts, Large Hail)
DC....MD....DE....PA....NJ....NY....CT....RI....MA....VT....NH....ME
HEAVY RAINFALL OUTLOOK
(potential for an inch or more total rainfall within the next 24 hours)
Isolated Locations In
DC....MD....DE....PA....NJ....NY....CT....RI....MA....VT....NH....ME
(QPF 1 - 3")
Isolated Locations In
OK....TX....LA....MS....AL....FL....GA....SC....NC....VA....WV....OH....KY....IN....IL
WI....MI....ON....QC
(QPF 1 - 2")
Scattered Locations In
BC....AB
(QPF 1 - 3")
Isolated Locations In
MT....ID....UT....N AZ....NM....CO....WY
(QPF 1 - 2")
EXCESSIVE HEAT OUTLOOK
(potential for maximum temperature to exceed 95 deg F within the next 24 hours)
NUMEROUS Locations In
CA....AZ....NV....S UT....S MT....WY....CO....NM....TX....OK.....W, C KS....W NE
W SD
TROPICAL WEATHER SUMMARY
(review of disturbances over the Atlantic Basin and Eastern Equatorial Pacific Ocean)
The character of ENSO in the equatorial Pacific Ocean has shifted to a neutral (3,4) and El Nino (1,2) signature in the oceanic sectors responsible for designating events. Current rate of warming of SSTs points toward a weak El Nino in place by August 1. Such a signal would indicate reduction of the window for hurricane formation from ITCZ waves originating in western Africa.
Other hydrothermal anomalies worth noting:
Warming of waters off of the West Coast. This signifies increased potential for strong ridging along and west of the Continental Divide. By later summer, this may result in a more westward orientation of hot temperatures.
Water temperatures across the entire western Atlantic Basin are normal or above average, which are favorable for tropical cyclone development and intensification.
Eastern Equatorial Pacific Ocean: Three ITCZ impulses from below Panama to well south of Baja California. Some organization is possible for the disturbance closest to Central America.
Atlantic Basin: Well-developed tropical wave about 800 miles east-southeast of Windward Islands. Strengthening is unlikely due to infiltration of dust and hot, dry air in its northern quadrants and the presence of shearing southwest flow aloft to the northwest of this system.
African ITCZ: Saharan heat ridge is limiting thunderstorm formation over the Sahel. Four strong convective circulations moving westward pose no immediate risk of tropical cyclone formation.
The Orient: Weakening Typhoon Fengshen is now passing through Luzon island. Fengshen may become a tropical storm or depression before re-intensification begins over the South China Sea. Later, this feature may strike or pass very close to Taiwan as a Category 1 typhoon. Also watch for a disturbance to the right of Fengshen, which may track northward toward Japan in an environment favorable to strengthening.
SHORT RANGE OUTLOOK
(Through The Next 72 Hours)
"High Humidity And Scattered Thunderstorms"
As can be seen in the attached QPH chart for Sunday, June 22, scattered showers and thunderstorms will be the dominant condition over much of the U.S. A weak 500MB trough over the Great Lakes and Ohio Valley will stimulate convection in Appalachia and the Eastern Seaboard, with some of the storms nearing or surpassing severe limits. Across the otherwise hot West, diurnal and orographic cumulonimbi will bring pockets of heavy rainfall, microbursts, and hail through the next few days.
Extreme Heat Rules Most Of Western Half Of The U.S.
Those who are lucky enough to be near a thunderstorm in the western states (or along the coastline of Oregon and Washington) may at least dodge two or three hours of intense heat. The powerful Sonoran heat ridge is beginning to flex toward the north and east, which in turn should bring some of the torrid values into the Great Plains. The Midwest and Northeast, meanwhile, with "leftover" or "stale" cooler air from Canada, may dodge the heat bullet until next Wednesday or Thursday.
MEDIUM RANGE OUTLOOK
(Four To Ten Days From Now)
Two Heat Ridges For The Price Of One
It is bad enough when one heat ridge affects the U.S. But an ongoing theme through the 6-10 and 11-15 day time frames is the presence of TWO subtropical highs, one of the Sonoran type and another in the Southeast (Great Smokies variety). Essentially, this creates a hot West and South, cooler Great Lakes and Northeast temperature pattern. But with every shortwave passing along the Canadian border, some of the high heat will find its way into major cities such as Minneapolis MN, Chicago IL, Cleveland OH, and New York NY.
Weakness Adds High Humidity Over Eastern Half Of Nation
The position of a weakness between the two heat ridge complexes (Sonoran and Great Smokies) will allow a stream of high dewpoints from the Gulf of Mexico to reach across most of the eastern half of the U.S. during the medium range and extended outlook. With available moisture and plentiful upper level dynamics in play, numerous diurnal thunderstorms can be expected to the right of the Mississippi River. The biggest issue, however, will be the unrelenting high humidity affecting energy consumers.
Severe Thunderstorms Shift Toward The Canadian Border
The numerical models and the respective ensemble forecasts have shown an impressive ridge building pattern, with much of the lower 48 states involved with heat ridge development through the next two weeks. By Day 10, the mean jet stream position should be parallel to and slightly above the Canadian border. That configuration almost always favors the best chance for thunderstorms, and with severe weather, running through the northern tier states.
EXTENDED PERIOD FORECAST
(Between Day 11 And Day 15)
Are We Locked Into A Pattern That Will Last For Much Of The Summer?
Since the same signals and signatures keep appearing on the various model forecasts (no, not the infamous "indices" which show no strong pattern identification of any kind....), it would appear that the weather evolving in the past two weeks will be a "keeper" for much of the summer. There has been a distinct shift in computer outlooks toward a massive western (+PNA) ridge complex, with a smaller Great Smokies heat ridge. If so, this will likely be a brutal summer in the West and in the Old South, with the Great Lake and Northeast in the normal to below average temperature realm. The threat for severe thunderstorms that has dominated the Midwest in the spring will very likely shift above Interstate 80 and to the right of Interstate 35 during the following 2 to 3 months.
Tropical Cyclone Chances May Be Increasing By Mid-July
There is a very subtle shift to lesser upper level shear in computer forecasts for the 11-5 day time period. Up until this time, we have seen two limiting factors for tropical cyclone development: a high volume of hot, dry, dusty air advected from the Saharan heat ridge and strong, shearing southwest flow aloft across much of the Atlantic Basin. The ITCZ has been quite active with multiple, intense impulses. With water temperature rises noted between western Africa and the Americas, I suspect that there will be a two month window (say July 15 to September 15) for important warm-core cyclogenesis. After that point, the budding El Nino episode will very likely exert a hostile vertical environment for tropical convection.
Prepared by Meteorologist LARRY COSGROVE on
Saturday, June 21, 2008 at 6:45 P.M. CT
Disclaimer:
The previous statements are my opinions only, and should not be construed as definitive fact. Links provided on this newsletter are not affiliated with WEATHERAmerica and the publisher is not responsible for content posted or associated with those sites.
Copyright 2008 by Larry Cosgrove
All rights reserved.
This publication may not be reproduced or redistributed in whole or in part without the expressed written consent of the author.