Weather analysis for 11 Aug 2007 with 12Z maps
For a real forecast, go to www.nws.noaa.gov.
Meanwhile, Hurricane Flossie ~snicker~ is out in the Pacific.
Northern hemisphere:
What looked like an omega block over Scandinavia isn't really a block after all-- the high slid down from the polar region and is making its way south and east. A broad area of high pressure dominates the eastern Pacific while a surface low has formed over Saskatchewan and Manitoba.
Southern hemisphere:
2 intense stacked polar low pressure systems (one has a 938mb surface low) with strong surface pressure gradients stand out immediately. There is an interesting feature south of Australia where the upper level contours have the opposite curvature of the surface contours. Not sure what to make of that.
North America:
3-hour pressure tendency map from the RUC suggests that the surface low in central Canada is moving northeast into Ontario and Hudson Bay. It also shows something moving off the coast of NC and SC into the Atlantic.
Theta-e contours show a baroclinic zone through Alberta, Saskatchewan, ND, and southeast MT associated with the low pressure system in Canada. Surface observations show a wind shift line from northwest MN through SD and into NE with cooler temperatures and lower dewpoints. A loop shows that the winds in that area uniformly changed direction with time, so this is definitely a cold front rather than a stationary front.
There is a jet stream from the Pacific into the US from CA through NV, UT, WY, SD, ND, and into MN. It appears to be curving around the ridge and/or joining with the more northerly jet stream. That is significant because an anticyclonically curved jet streak has a different pattern of upper level convergence/divergence than a straight jet streak.
There is Q-vector convergence at 850mb over eastern MN, western WI, and Lake Superior, consistent with a short wave trough seen on the RUC but not on satellite.
Streamlines at 850mb show a high centered over the TX/AR/LA/OK region and a col over the Great Lakes. St 700mb, the center of the high is slightly north of its 850mb position, but at 500mb the high center is over southeast NM. That rapid spatial shift from 700mb to 500mb is unusual and I'm not sure what to make of it. At 250mb, the center is back over TX/AR/LA/OK.
From forecast discussions:
La Crosse, WI: DATA ANALYSIS EARLY THIS MORNING HAD HIGH PRESSURE CENTERED OVER THE GREAT LAKE REGION AS LOW PRESSURE AND A COLD FRONT WERE PUSHING EAST ACROSS THE DAKOTAS
Wilmington, NC: NORTHWEST FLOW WILL CONTINUE AT THE MID-LEVELS AS RIDGE RETROGRADES TO THE WEST. AT THE SURFACE...FRONTAL BOUNDARY CURRENTLY SITUATED JUST TO THE NORTHWEST OF THE AREA WILL CONTINUE TO PUSH EVER SO SLOWLY TO THE SOUTHEAST.
I saw the baroclinic zone they're talking about but didn't believe it was real since it stretched out into the ocean where there is generally a lack of data.
Albuquerque, NM: TONIGHT/S WATER VAPOR IMAGERY ALSO DEPICTS AN EASTERLY WAVE MOVING
ONTO MEXICO/S EAST COAST FROM THE GULF. THIS WAVE WILL CROSS CENTRAL AND NORTHERN PORTIONS OF MEXICO THIS WEEKEND...AND INDUCE
AN INVERTED TROUGH THAT WILL TRAVEL NORTHWESTWARD THROUGH ARIZONA AND
WESTERN NEW MEXICO ON MONDAY.
D'oh! I forgot to check water vapor. Sure enough, there it is. There's also another wave that's just about to cross FL.
Meanwhile, Hurricane Flossie ~snicker~ is out in the Pacific.
Northern hemisphere:
What looked like an omega block over Scandinavia isn't really a block after all-- the high slid down from the polar region and is making its way south and east. A broad area of high pressure dominates the eastern Pacific while a surface low has formed over Saskatchewan and Manitoba.
Southern hemisphere:
2 intense stacked polar low pressure systems (one has a 938mb surface low) with strong surface pressure gradients stand out immediately. There is an interesting feature south of Australia where the upper level contours have the opposite curvature of the surface contours. Not sure what to make of that.
North America:
3-hour pressure tendency map from the RUC suggests that the surface low in central Canada is moving northeast into Ontario and Hudson Bay. It also shows something moving off the coast of NC and SC into the Atlantic.
Theta-e contours show a baroclinic zone through Alberta, Saskatchewan, ND, and southeast MT associated with the low pressure system in Canada. Surface observations show a wind shift line from northwest MN through SD and into NE with cooler temperatures and lower dewpoints. A loop shows that the winds in that area uniformly changed direction with time, so this is definitely a cold front rather than a stationary front.
There is a jet stream from the Pacific into the US from CA through NV, UT, WY, SD, ND, and into MN. It appears to be curving around the ridge and/or joining with the more northerly jet stream. That is significant because an anticyclonically curved jet streak has a different pattern of upper level convergence/divergence than a straight jet streak.
There is Q-vector convergence at 850mb over eastern MN, western WI, and Lake Superior, consistent with a short wave trough seen on the RUC but not on satellite.
Streamlines at 850mb show a high centered over the TX/AR/LA/OK region and a col over the Great Lakes. St 700mb, the center of the high is slightly north of its 850mb position, but at 500mb the high center is over southeast NM. That rapid spatial shift from 700mb to 500mb is unusual and I'm not sure what to make of it. At 250mb, the center is back over TX/AR/LA/OK.
From forecast discussions:
La Crosse, WI: DATA ANALYSIS EARLY THIS MORNING HAD HIGH PRESSURE CENTERED OVER THE GREAT LAKE REGION AS LOW PRESSURE AND A COLD FRONT WERE PUSHING EAST ACROSS THE DAKOTAS
Wilmington, NC: NORTHWEST FLOW WILL CONTINUE AT THE MID-LEVELS AS RIDGE RETROGRADES TO THE WEST. AT THE SURFACE...FRONTAL BOUNDARY CURRENTLY SITUATED JUST TO THE NORTHWEST OF THE AREA WILL CONTINUE TO PUSH EVER SO SLOWLY TO THE SOUTHEAST.
I saw the baroclinic zone they're talking about but didn't believe it was real since it stretched out into the ocean where there is generally a lack of data.
Albuquerque, NM: TONIGHT/S WATER VAPOR IMAGERY ALSO DEPICTS AN EASTERLY WAVE MOVING
ONTO MEXICO/S EAST COAST FROM THE GULF. THIS WAVE WILL CROSS CENTRAL AND NORTHERN PORTIONS OF MEXICO THIS WEEKEND...AND INDUCE
AN INVERTED TROUGH THAT WILL TRAVEL NORTHWESTWARD THROUGH ARIZONA AND
WESTERN NEW MEXICO ON MONDAY.
D'oh! I forgot to check water vapor. Sure enough, there it is. There's also another wave that's just about to cross FL.