November 2015: Ending Cold & Rainy

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Andrew
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GFS is suggesting one hell of a system coming through the southern plains. A strong trough with multiple shortwaves rotating through looks to present a very wet beginning to next week. The GFS is even showing a possible severe event with EHI's in the 4-5 range. Of course this is all 5-6 days away, but we could see our first cold event of the year.
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Very thin but organized squall line headed towards metro in the next hour or two.
Surprising how well its held together for it being so thin. 10 degree drop with fropa.
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Ptarmigan
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Andrew wrote:GFS is suggesting one hell of a system coming through the southern plains. A strong trough with multiple shortwaves rotating through looks to present a very wet beginning to next week. The GFS is even showing a possible severe event with EHI's in the 4-5 range. Of course this is all 5-6 days away, but we could see our first cold event of the year.
Another flood event possible? November has had nasty weather, especially with El Nino.
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Ptarmigan
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snowman65 wrote:DARK BLUE = I like! :D :D
Lower pressure means stormy weather.
Andrew
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Ptarmigan wrote:
Andrew wrote:GFS is suggesting one hell of a system coming through the southern plains. A strong trough with multiple shortwaves rotating through looks to present a very wet beginning to next week. The GFS is even showing a possible severe event with EHI's in the 4-5 range. Of course this is all 5-6 days away, but we could see our first cold event of the year.
Another flood event possible? November has had nasty weather, especially with El Nino.

The possibility exists but there still remains a lot of questions as to how progressive the system will be and where everything sets up.
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Katdaddy
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Temps are cooling and light rains moving offshore as the front moves across the Upper TX Coast. Partly cloudy skies through Saturday afternoon before rain chances begin to increase Saturday night. Models continue to show a powerful upper level low moving across TX Monday and Tuesday with the potential of a severe weather event as well as a heavy rain event. The SPC has SE TX in the 15% hatch area for severe weather Monday and Tuesday. A strong cold front will follow the storm system next week.
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srainhoutx
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The overnight guidance continues to advertise a powerful negative tilted trough moving out of the Southern Rockies Sunday into Monday and marching across Texas and Louisiana into Tuesday. If these trends continue, except to see all modes of severe weather possible including a threat for super cells and a possible tornado risk across portions of Central, East, SE Texas extending into Louisiana next Monday into Tuesday.

In the wake of this powerful late Fall/early Winter storm, expect the coldest air of the Season to spread South all the way to the Gulf Coast mid to late next week. Stay tuned folks. This storm system has the potential to be a Major Weather event across the Region.

00Z Euro:
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00Z GFS
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srainhoutx wrote:The overnight guidance continues to advertise a powerful negative tilted trough moving out of the Southern Rockies Sunday into Monday and marching across Texas and Louisiana into Tuesday. If these trends continue, except to see all modes of severe weather possible including a threat for super cells and a possible tornado risk across portions of Central, East, SE Texas extending into Louisiana next Monday into Tuesday.

In the wake of this powerful late Fall/early Winter storm, expect the coldest air of the Season to spread South all the way to the Gulf Coast mid to late next week. Stay tuned folks. This storm system has the potential to be a Major Weather event across the Region.
Sounds like some exciting days ahead.This may be a precursor of what's ahead for our winter weather. :)
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EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
152 AM EST THU NOV 12 2015

VALID 12Z SUN NOV 15 2015 - 12Z THU NOV 19 2015

...HEAVY RAIN POSSIBLE IN THE MID AND LOWER MISSISSIPPI VALLEY
NEXT TUE-WED...

...OVERVIEW...
HIGH PRESSURE WILL ANCHOR OFF THE EAST COAST FOR THE BETTER PART
OF THIS MEDIUM RANGE PERIOD --- PRODUCING A WEAK ONSHORE FLOW THAT
WILL GENERATE LOCALLY CLOUDY CONDITIONS...BUT OVERALL A DRY AND
RATHER MILD PATTERN BY MID-NOVEMBER STANDARDS. THE WEATHER IN THE
WEST WILL HAVE AN UNUSUAL 'ALASKA' FEEL TO IT ... AND THE CENTRAL
PORTION OF THE CONTINENT ... MORE LIKE 'SPRING' WITH COOL
NIGHTS...MILD DAYS AND THREAT OF SHOWERS ALONG AND AHEAD OF THE
'PACIFIC' FRONTS MIGRATING DOWNWIND OF THE ROCKIES.

A DEEP CYCLONE MIGRATING ACROSS THE GULF OF ALASKA (IN THE SHORT
TERM) WILL BE A MAJOR SENSIBLE WEATHER FEATURE OF THE LOWER 48'S
WEATHER PATTERN DURING THE MEDIUM RANGE PERIOD. THE DEPTH OF THIS
SYSTEM AND ITS DEEP SURGE OF MODIFIED ARCTIC AIR --- WITH ORIGINS
IN NORTHEAST SIBERIA --- WILL BE TEMPORARILY LINKED WITH THE GULF
OF ALASKA AND NORTH AMERICA'S WEST CENTRAL COAST ---VIA A RATHER
PERSISTENT AND ACTIVE WEST-NORTHWESTERLY 250MB JET AXIS. THIS
POLAR JET BEGINS TO CARVE OUT A DEEP 250MB TROUGH ON DAY 3 ALONG
THE WEST COAST --- AND MIGRATES THIS SYNOPTIC-SCALE FEATURE
EASTWARD ACROSS THE CENTRAL PORTION OF THE CONTINENT THROUGH DAY 5
AND 6. IT'S EVENTUAL INTERACTION WITH A SOUTHERN JET AXIS WITH
ORIGINS NEAR HAWAI'I --- SHOULD SET THE STAGE FOR LARGE SENSIBLE
WEATHER CHANGES IN THE SOUTHERN ROCKIES AND PLAINS (DAYS 3-4) AND
MUCH OF THE MISSISSIPPI VALLEY (DAY 5).

...MODEL PREFERENCES...
HAVING THE LUXURY OF WATCHING THE EVOLUTION OF THIS PARTICULAR
SUB-968MB ALASKA CYCLONE LAST WEEK --- AND SEEING ITS RATHER DEEP
CENTER MIGRATING THIS MORNING --- TO A LOCATION VERY NEAR WHERE
THE ECMWF/GFS HAD IT 5-6 DAYS AGO... IT GIVES ME SOME CONFIDENCE
TO CONCLUDE WHERE IT WILL BE IN THE NEXT 4-5 DAYS. IN A WEAKENED
STATE --- OVER NORTH CENTRAL CANADA. BUT MORE IMPORTANTLY... IT'S
WHAT TRANSPIRES BEHIND IT AND WHERE THE TRAJECTORIES OF THE ARCTIC
AIR ASSOCIATED WITH THE MID-AUTUMN SYSTEM ARE HEADING ... THAT
POINTS TO USING A BLEND OF THE DETERMINISTIC 11/12Z-12/00Z
GFS/ECMWF THROUGH DAY 5. IN ADDITION... THESE PIECES OF GUIDANCE
CONTINUE TO PROVIDE GOOD BALANCE ---AND A SPLIT-FLOW OFF THE
CENTRAL CALIFORNIA COAST --- WITH A 100+ KT SUBTROPICAL SOUTHERN
JET AXIS EMERGING NORTH AND NORTHEAST OF HAWAI'I--- WITH AN ENTRY
POINT NEAR 30N 115W.

THIS 'SPLIT-FLOW' WILL NOT LAST LONG --- AND BY DAY 3 --- THE
NORTHERN STREAM BEGINS TO WORK ITS WAY SOUTH ALONG THE WASHINGTON
AND OREGON COAST... AND WILL BLEND BOTH THE 12/00Z DETERMINISTIC
ECMWF/GFS SOLUTIONS AND THEIR MEANS FOR THE DAY 4-5 QPFS. BEYOND
18/00Z ... THE DIFFERENCES BETWEEN THE GFS/ECMWF BECOME VERY
APPARENT --- AND VERY QUICKLY DO THE TWO JET STREAM DEVELOP A VERY
COMPLEX UPPER-LEVEL FLOW PATTERN NEAR THE OZARKS (AROUND 18/06Z).
AND THIS IS THE BEST DETAIL I CAN GIVE AT THIS POINT. USED A
11/12Z 70/30 ECENS/NAEFS BLEND FOR DAYS 6-7 TO ACCOUNT FOR THE
RATHER SHARP AMPLITUDE AND CHANGING CHARACTER OF THIS PARTICULAR
MIGRATORY 250MB PACIFIC TROUGH SEQUENCE.

...UNCERTAINTY ASSESSMENT...
BIGGEST UNCERTAINTY AT THIS POINT IN TIME IS --- HOW FAR SOUTH AND
FOR HOW LONG --- THE UNSTABLE PORTION OF THE NORTHERN STREAM
PACIFIC JET ("BACKSIDE") WILL DRIFT ONCE IT ENTERS THE WEST COAST
(ON/AROUND 16/12Z). THIS PORTION OF THE JET WILL CARRY A LARGE
PORTION OF THE ALEUTIAN/GULF OF ALASKA MARITIME POLAR AIRMASS WITH
IT SOUTHEASTWARD TOWARDS THE MAINLAND. THE JET-DRIVEN HEAVY
PRECIPITATION DIRECTED ACROSS THE COASTAL RANGES OF
WASHINGTON...THE WINDWARD OREGON CASCADES AND NORTHERN CALIFORNIA
IS A SCENARIO THAT HAS ABOUT A 48-HOUR LIFE CYCLE BETWEEN DAY 4
AND DAY 6 (PER THE 11/12Z-12/00Z DETERMINISTIC GFS/ECMWF). AND
BEHIND THE EXITING JET --- THE COLDEST AIRMASS OF THE YOUNG 'WET
SEASON' SPREADS INTO THE PACIFIC NORTHWEST.

HEADING INTO THE DAY 4-5 PERIOD...THE DETERMINISTIC GUIDANCE LIKES
THE IDEA OF THE SOUTHERN JET STREAM BEGINNING TO NOSE EASTWARD
INTO THE OZARKS AND LOWER MS VALLEY. BUT HOW MUCH OF THIS
JET-LEVEL ENERGY CAN PHASE WITH THE PREVAILING PACIFIC STREAM
PUNCHING ACROSS THE WEST COAST AND GREAT BASIN WILL BE THE
CHALLENGE.

MOVING FORWARD FROM 17/12Z (TUESDAY MORNING)... THERE ARE THREE
DIFFERENT SOLUTIONS WITH THE EASTWARD PROGRESSION OF THE 'PACIFIC'
FRONT---THE NORTHWARD SPREAD OF THE PRECIPITATION ALONG THIS
SOUTHERN JET AXIS AND HOW THE TWO 250MB JET AXES INTERACT AT/AND
BEYOND 18/06Z. FOR NOW --- THE 11/12Z GFS AND CANADIAN MAINTAIN A
HEAVY RAIN THREAT INTO WEDNESDAY --- THE 11/12Z ECMWF PUSHES THE
HEAVY RAINFALL DOWNWIND INTO THE APPALACHIANS. NO DOUBT --- THE
WESTERN GULF OF MEXICO WILL PARTIALLY-OPEN AND ALLOW A BROAD
LOW-LEVEL MOISTURE STREAM TO WORK NORTHWARD...BUT THE UNCERTAINTY
REMAINS IN THE ABILITY OF THE SOUTHERN JET TO GENERATE THE LIFT
AND PHASE WITH THE UPSTREAM SURFACE FRONT AND 250MB NORTHERN
STREAM JET MOVING THROUGH THE NORTHERN PLAINS. THIS IS THE PRIMARY
REASON BEHIND USING A 11/12Z ECENS/NAEFS BLEND WITH NO
DETERMINISTIC SUPPORT FOR DAY 6-7 SURFACE GRAPHICS AND QPFS.
SHOULD THESE TWO JET STREAMS PHASE --- THERE WILL BE POTENTIAL FOR
EVEN MORE HEAVY RAINFALL TO MIGRATE NORTHWARD INTO THE OHIO VALLEY
AND GREAT LAKES.

...SENSIBLE WEATHER HIGHLIGHTS...
MORE RAIN AND COLD-SECTOR SHOWERS FOR A LARGE PORTION OF THE WEST
AS THE LEADING EDGE OF THE DEEP TROUGH IN THE GULF OF ALASKA
MIGRATES EAST OF THE COASTAL RANGES AND BEGINS TO WORK ITS WAY TO
THE CONTINENTAL DIVIDE.

THE COMBINED EFFECTS OF TWO JET DISTINCTLY DIFFERENT 250MB JET
AXES --- A PACIFIC FRONT MOVING THROUGH THE CENTRAL PLAINS AND A
PARTIALLY-OPEN WESTERN GULF OF MEXICO ALL POINT TO THE POTENTIAL
FOR MORE HEAVY RAIN ACROSS PORTIONS OF TEXAS... OKLAHOMA... THE
OZARKS... AND MUCH OF THE SOUTHERN HALF OF THE MISSISSIPPI RIVER
VALLEY DURING THE EARLY PORTION OF THIS MEDIUM RANGE PERIOD.

VOJTESAK



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srainhoutx
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Worrisome to see very good agreement among the 12Z suite of operational guidance concerning the next in a series of powerful Southern Storms...
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