FORECAST/NOWCAST: USA 2009

[Severestorms]

Nachdem sich der bereits eröffnete Thread FORECASTING: Tornado-Hochsaison im Mai 2009 in den USA hauptsächlich um die "Vorhersage" der tornadischen Aktivität in den USA zur Tornado-Hochsaison (also im Mai 2009) drehen soll, möchte ich diesen Thread hier eröffnen, um allgemein interessantes Wetter in den USA währen des gesamten Jahres 2009 zu diskutieren (analog dem letztjährigen USA Forecasting/Nowcasting 2008).

Die Eröffnung geschieht nicht zufällig, sondern aus gegebenem Anlass..

Denn momentan betrachtet, könnte der kommende Sonntag/Montag für einige Gebiete des Mittleren Westens in Sachen Schwergewitter äusserst spannend werden. Ein kräftiger Kurzwellentrog, verbunden mit viel Hebung und starker Scherung soll über das besagte Gebiet ziehen. Das SPC hat in ihrem 4-8 Day Convective Outlook denn auch bereits eine entsprechende Vorwarnung drin. Immerhin bedeutet das gemäss Definition: "A severe weather area depicted in the Day 4-8 period indicates a 30% or higher probability for severe thunderstorms within 25 miles of any point."



DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0313 AM CST WED FEB 04 2009

VALID 071200Z - 121200Z

...ACTIVE SEVERE WEATHER PATTERN FORECAST OVER AREAS OF THE
SOUTHERN/CENTRAL U.S. NEXT WEEK...

...DAY5/SUNDAY TO MONDAY MORNING...
MREF AND RECENT GFS RUNS CONTINUE TO EXHIBIT GOOD RUN-TO-RUN
CONSISTENCY IN THE DEVELOPMENT OF A VIGOROUS SHORT WAVE TROUGH
EJECTING NEWD FROM AZ TO THE SRN/CNTRL PLAINS SUNDAY INTO MONDAY.
ECMWF CONTINUES TO BE TYPICALLY SLOWER THAN THE GFS WITH THE TROUGH
POSITION THROUGH 120 HOURS/SUNDAY EVENING. BUT...RECENT ECMWF RUNS
HAVE BEEN TRENDING TOWARD A MORE PROGRESSIVE/EWD H5 TROUGH POSITION
NOW IN CLOSE AGREEMENT WITH THE MREF H5 MEAN. THIS LENDS CONFIDENCE
IN THE SYNOPTIC PATTERN BEING FORECAST ACROSS THE SRN PLAINS BY
SUNDAY EVENING.

GIVEN PRONOUNCED LARGE SCALE JET COUPLING AND STRENGTHENING ASCENT
DEVELOPING ACROSS TX/OK/KS THROUGH SUNDAY...DYNAMIC AND KINEMATIC
ENVIRONMENT SHOULD INCREASINGLY SUPPORT THE DEVELOPMENT OF SEVERE
STORMS WITH HAIL AND HIGH WINDS. AIR MASS QUALITY WILL OBVIOUSLY
PLAY A ROLE IN OVERALL SEVERE STORM COVERAGE AND MODE. NUMEROUS
RECENT INTRUSIONS OF COLD/DRY AIR INTO THE NW GULF SUGGEST THAT
MOISTURE RETURN AND RESULTANT CAPE WITH THIS UPCOMING SYSTEM WILL
LIKELY BE LIMITED. HOWEVER...THIS LIMITING FACTOR SHOULD BE SOMEWHAT
OFFSET BY THE MAGNITUDE OF FORCING AND SHEAR FORECAST TO ACCOMPANY
THE UPPER TROUGH...SURFACE LOW...AND FRONT MOVING OVER THE REGION
THROUGH SUNDAY NIGHT/MONDAY MORNING.

...DAY6/MONDAY TO TUESDAY MORNING...
PRIMARY MID/UPPER LEVEL DISTURBANCE/VORT MAX AND SURFACE LOW ARE
FORECAST TO LIFT NWD/NEWD TO THE UPPER MS VALLEY THROUGH EARLY
TUESDAY. IT APPEARS POSSIBLE THAT SEVERE STORMS...POSSIBLY TAKING
THE FORM OF A SQUALL LINE...MAY SPILL OVER FROM SUNDAY INTO MONDAY
FROM THE OZARKS TO ARKLATEX. OR...STORMS MAY REDEVELOP ALONG THIS
AXIS DURING THE DAY. THIS ACTIVITY MAY STRENGTHEN DURING THE DAY
WITHIN CONFLUENT WARM CONVEYOR BELT WHERE DEEP-LAYER SHEAR SHOULD BE
MORE THAN ADEQUATE FOR ORGANIZED/PERSISTENT UPDRAFTS/SUPERCELLS.

...DAY7-8/THROUGH MIDWEEK...
LARGE SCALE PATTERN IS FORECAST TO REMAIN QUITE ACTIVE/DYNAMIC WITH
GFS AND ECMWF BOTH FORECASTING ANOTHER DEEP TROUGH DEVELOPING OVER
THE PLAINS ON WEDNESDAY/DAY8. HOWEVER...IN THE WAKE OF POTENTIALLY
WIDESPREAD CONVECTION ACROSS THIS REGION ON PRIOR DAYS...SEVERE
STORM PREDICTABILITY AT THIS FORECAST RANGE IS LOW.

..CARBIN.. 02/04/2009

Quelle: http://www.spc.noaa.gov/products/exper/day4-8/

Bleibt also zu beobachten..

Gruss Chrigi

[Badnerland]

Sonntag 08.02.2009:

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0148 PM CST SUN FEB 08 2009

VALID 082000Z - 091200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN HIGH
PLAINS...

...SRN HIGH PLAINS...
WATER VAPOR IMAGERY CURRENTLY SHOWS A LARGE NEGATIVELY-TILTED
UPPER-LEVEL TROUGH FROM THE DESERT SOUTHWEST ORIENTED SSEWD ALONG
THE GULF OF CALIFORNIA. THIS SYSTEM IS FORECAST TO MOVE QUICKLY
ENEWD ACROSS THE FOUR CORNERS REGION AND NRN MEXICO TODAY. AHEAD OF
THE TROUGH...RUC ANALYSIS SHOWS THE LEADING EDGE OF STRONG
LARGE-SCALE ASCENT LOCATED JUST WEST OF EL PASO ON THE NRN END OF A
WELL-DEVELOPED DRY SLOT. THIS ZONE OF STRONG ASCENT ASSOCIATED WITH
A NARROW BAND OF MID-LEVEL MOISTURE WILL MOVE ENEWD INTO ERN NM BY
LATE THIS AFTERNOON WHERE RUC ANALYSIS SUGGESTS LOW-LEVEL
CONVERGENCE IS INCREASING. CONVECTION APPEARS LIKELY TO FIRST
INITIATE ALONG THIS BAND OF ASCENT IN NERN NM WITH CONVECTION
QUICKLY EXPANDING SWD ACROSS FAR ERN NM INTO THE PECOS RIVER VALLEY
BY EARLY TO MID EVENING. THE LINE OF CONVECTION WILL LIKELY
INTENSIFY...MOVING EWD ACROSS WEST TX DURING THE LATE EVENING AND
OVERNIGHT PERIOD.

CONCERNING THE SEVERE POTENTIAL...SEVERAL FACTORS ARE COMING
TOGETHER ACROSS ERN NM AND WEST TX FOR THE POTENTIAL FOR SEVERE
STORMS. 1) THE RUC IS CURRENTLY ANALYZING A POCKET OF INSTABILITY
OVER SE NM WHERE SBCAPE VALUES RANGE FROM 250 TO 500 J/KG. THIS
INSTABILITY SHOULD GRADUALLY INCREASE AND MAY EXPAND EWD INTO PARTS
OF WEST TX THROUGH THE LATE AFTERNOON. 2) THE RUC SHOWS STRONG
VERTICAL SHEAR /0-6 KM SHEAR OF 50 TO 70 KT/ OVER THE WRN HALF OF
THE SLIGHT RISK AREA. 3) A 40 TO 50 KT LOW-LEVEL JET IS ANALYZED
OVER WCNTRL TX. THIS FEATURE WILL EXPAND NNWWD STRENGTHENING TO
ABOUT 60 KT THIS EVENING. AS THE STRONG ASCENT COMES OUT INTO THE
HIGH PLAINS...THE INSTABILITY...VERTICAL SHEAR AND STRONG LOW-LEVEL
FLOW SHOULD SUPPORT A POTENTIAL FOR SEVERE THUNDERSTORMS. ALTHOUGH
THE CONVECTION SHOULD BE ORIENTED IN A GENERAL LINE FROM NORTH TO
SOUTH ACROSS WEST TX...SMALLER SCALE LINE-SEGMENTS SHOULD BE CAPABLE
OF PRODUCING ISOLATED DAMAGING WIND GUSTS. THE HAIL THREAT SHOULD BE
MORE CONFINED TO A NARROW CORRIDOR ALONG THE NM-TX STATE-LINE WHERE
MID-LEVEL LAPSE RATES ARE FORECAST TO BE STEEPER AND TEMPS WILL BE
COLD ALOFT NEAR THE APPROACHING UPPER-LEVEL TROUGH. IF A VIGOROUS
SQUALL-LINE CAN CONTINUE OVERNIGHT IN SPITE OF WEAK
INSTABILITY...THEN THE WIND DAMAGE THREAT COULD EXTEND AS FAR EAST
AS WRN OK LATE IN THE PERIOD.

..BROYLES.. 02/08/2009

Interessante Übersicht dazu in der WZ:
http://www.wzforum.de/forum2/read.php?2,1538108

Reports dazu:


Und auch die kommenden Tage sehen interessant aus...
http://www.spc.noaa.gov/products/

Gruss Benni

[Badnerland]

10.02.2009:
Großräumiges Moderate Risk für heute:

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1208 AM CST TUE FEB 10 2009

VALID 101200Z - 111200Z

...THERE IS A MDT RISK OF SVR TSTMS ACROSS ERN OK...NORTH CENTRAL
AND NERN TX...NWRN LA...AND MUCH OF AR FOR LATE THIS AFTERNOON INTO
TUESDAY NIGHT...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MODERATE RISK
FROM EAST TX/LA NWD TO LOWER MO/MID MS VALLEYS...

...SIGNIFICANT SEVERE WEATHER OUTBREAK INCLUDING TORNADOES AND
DAMAGING WINDS IS EXPECTED TO DEVELOP LATE THIS AFTERNOON AND
PERSIST INTO TUESDAY NIGHT ACROSS THE ERN HALF OF OK...NORTH
CENTRAL-NERN TX INTO NWRN LA AND MUCH OF AR...

...SYNOPSIS...
STRONG UPPER TROUGH...CURRENTLY MOVING THROUGH THE LOWER CO RIVER
VALLEY WITH AN ACCOMPANYING 95 KT MID LEVEL JET MAX...WILL TRANSLATE
EWD REACHING THE SRN HIGH PLAINS BY 00Z. THIS TROUGH WILL THEN
BECOME NEGATIVELY TILTED AND DEEPEN TUESDAY NIGHT AS IT TRACKS ENEWD
TOWARD ERN KS/ERN OK. MODELS SUGGEST A SMALL CLOSED LOW SHOULD
DEVELOP OVER SERN KS/ERN OK BY 12Z WEDNESDAY. A 90+ KT MID LEVEL
JET WILL SPREAD EWD ACROSS NRN TX AND OK TUESDAY NIGHT...WITH THE
STRONGEST CORE OF MID LEVEL WINDS /110 KT/ EXPECTED TO SPREAD ACROSS
NRN TX TO THE ARKLATEX BY 12Z WEDNESDAY.

WHILE MODELS TEND TO AGREE WITH THE TRACK OF THE UPPER TROUGH...THEY
DIFFER WITH THE TRACK OF THE PRIMARY SURFACE LOW. THE NAM IS THE
FARTHEST NORTH TAKING THE LOW ACROSS KS INTO CENTRAL MO THIS
FORECAST PERIOD...WHILE THE GFS SUGGESTS THE SURFACE LOW WILL TRACK
ENEWD ACROSS CENTRAL/NRN OK INTO SRN MO BY 12Z WEDNESDAY. A FAIRLY
LARGE WARM SECTOR SHOULD DEVELOP TODAY... EXTENDING NWD THROUGH ERN
KS AND MUCH OF MO AS SLY LOW LEVEL WINDS TRANSPORT MOISTURE NWD...
WITH A WARM FRONT POSSIBLY REACHING NRN MO INTO CENTRAL IL. A
PACIFIC COLD FRONT ACCOMPANYING THE UPPER TROUGH WILL MOVE INTO
CENTRAL PARTS OF OK/TX BY MID-LATE AFTERNOON WHERE IT WILL MERGE
WITH A DRY LINE. THIS FRONT IS PROGGED TO SURGE EWD REACHING ERN
MO...ERN AR...AND EXTEND SWWD INTO THE NWRN GULF BY 12Z WEDNESDAY.

...SRN PLAINS/LOWER MS VALLEY NWD TO NRN MO/MID MS VALLEY...
LOW LEVEL MOISTURE RETURNING NWD ACROSS THE WARM SECTOR TODAY
BENEATH A PLUME OF STEEP MID LEVEL LAPSE RATES EMANATING NEWD FROM
THE MEXICAN PLATEAU WILL AID IN DESTABILIZATION. SURFACE DEWPOINTS
IN THE LOWER 60S ARE EXPECTED TO REACH NERN TX/SERN OK AND INTO
CENTRAL AR. ALTHOUGH CLOUDINESS WILL TEND TO LIMIT SURFACE HEATING
EAST OF THE DRY LINE...A MODERATELY UNSTABLE AIR MASS IS EXPECTED TO
DEVELOP ACROSS CENTRAL/ERN OK INTO CENTRAL/ NERN TX.

MODELS CONTINUE TO SUGGEST TSTM DEVELOPMENT WILL BE POSSIBLE BY
EARLY-MID AFTERNOON ACROSS PARTS OF ERN TX/SERN OK INTO ADJACENT
PARTS OF AR/LA. SOME SURFACE HEATING WITHIN THE MOISTURE RETURN
SHOULD PROVE SUFFICIENT FOR CONVECTION TO DEVELOP WITHIN A WEAKLY
CAPPED AIR MASS. DIFFLUENT FLOW ALOFT ACROSS THE ARKLATEX REGION BY
AFTERNOON SUGGESTS THIS EARLY ACTIVITY SHOULD BE DISCRETE... WHILE
STRENGTHENING SLY WINDS ACROSS THIS AREA INTO THE AFTERNOON WILL
RESULT IN CURVED HODOGRAPHS/TORNADO POTENTIAL.

GREATER SEVERE WEATHER THREAT IS EXPECTED TO DEVELOP ALONG THE DRY
LINE IN CENTRAL OK TO CENTRAL TX BY LATE AFTERNOON /AFTER 21Z/...
GENERALLY ALONG OR JUST EAST OF THE I-35 CORRIDOR. ADDITIONAL
STRENGTHENING OF THE SLY LLJ /50+ KT/ FROM E TX/LA TO ERN KS/MO WILL
RESULT IN LARGE CURVED HODOGRAPHS AND THE LIKELIHOOD FOR
STRONG/SIGNIFICANT TORNADOES AS STRONG UPPER FORCING WITH THE TROUGH
SPREADS INTO THE SRN PLAINS. IF CONFIDENCE BECOMES GREATER IN THE
TRACK OF THE PRIMARY SURFACE LOW...PORTIONS OF THE MODERATE RISK
AREA MAY NEED TO BE UPGRADED TO A HIGH RISK.

A SIGNIFICANT DAMAGING WIND THREAT IS FORECAST TO DEVELOP BY EARLY
TUESDAY EVENING AS THE COLD FRONT OVERTAKES THE DRY LINE...AND
STRONG WLY LOW-MID LEVEL WINDS SPREAD EWD ACROSS SRN OK/NRN TX
REACHING THE ARKLATEX REGION BY 11/09Z AND INTO NRN LA AND CENTRAL
AR LATE IN THE PERIOD.

AS THE WARM SECTOR SPREADS FARTHER N TOWARD THE LOWER MO VALLEY...
TSTM ACTIVITY DEVELOPING THIS EVENING ACROSS OK/AR WILL TRACK NEWD
WITH THERMODYNAMIC/KINEMATICS FAVORABLE FOR HAIL...STRONG WINDS AND
POSSIBLY TORNADOES EXTENDING THROUGH ERN KS AND MUCH OF MO.

..PETERS.. 02/10/2009

http://www.spc.noaa.gov/products/

Gruss Benni

[Bernhard Oker]

Hallo

Ev. könnte es heute sogar das erste High-Risk geben wie im Outlook angedeutet.

Stormtrack Forum Forecast Thread:
http://www.stormtrack.org/forum/showthread.php?t=19368

US TV Stationen falls es einen Live-Stream gibt:
http://www.mondotimes.com/world/usa/tv.html

Gruss
Bernhard

[Bernhard Oker]

Es dürfte bald einmal losgehen in den Plains:

Erste Mesoscale Discussion des SPC:
http://www.spc.noaa.gov/products/md/md0082.html

SUPERCELL STORM DEVELOPMENT IS EXPECTED IN THE NEXT 1-2 HOURS FROM S
CENTRAL OKLAHOMA SWWD INTO PARTS OF CENTRAL TX. RESULTING SEVERE
THREAT -- INCLUDING THE POTENTIAL FOR TORNADOES -- WILL REQUIRE
TORNADO WATCH ISSUANCE.

Gruss
Bernhard

[Badnerland]

Und gleich das erste Tornado-Watch hinterher, scheint wohl zu zünden. Auch im Outlook von heute Nachmittag großes Gebiet mit Moderate Risk und angedeutetes High Risk:

-----
...DRYLINE INITIATION OK/TX...
GIVEN LATEST MODEL GUIDANCE AND OBSERVATIONAL TRENDS...
THUNDERSTORMS ARE EXPECTED TO DEVELOP 20-22Z ALONG DRYLINE OVER
WESTERN OK AND NORTHWEST TX. THESE STORMS WILL LIKELY BE
SUPERCELLULAR WITH A RISK OF VERY LARGE HAIL AND TORNADOES. THE
STORMS WILL BECOME MORE NUMEROUS BY EARLY EVENING /AFTER DARK/ AND
TRACK NORTHEASTWARD INTO NORTHEAST TX AND EASTERN OK. MUCH STRONGER
VERTICAL SHEAR PROFILES IN THIS REGION /EFFECTIVE HELICITY OF 400+
M2/S2/ WILL ALSO INCREASE THE RISK OF STRONG TORNADOES. HAVE CHOSEN
TO MAINTAIN CATEGORICAL MODERATE RISK FOR THIS AFTERNOON DUE TO
CONTINUED CONCERNS OVER THE QUALITY OF LOW LEVEL MOISTURE...BUT AN
UPGRADE TO HIGH RISK WILL REMAIN POSSIBLE AT 20Z.
-----

http://www.spc.noaa.gov/products/

Gruss Benni

[Markus Pfister]

Und los gehts!
http://www.sturmforum.ch/forum_uploads/ ... r_frei.gif

Unglaublich, ein Superzellen-Umzug mit *mindestens* 4 Nummern, und alle quasi vom selben Strassenrand aus zu geniessen: http://www.sturmforum.ch/forum_uploads/ ... r_frei.gif

Und hier etwas Doppler-Training (lol - nicht wirklich): Wo ist der Tornado?
http://www.sturmforum.ch/forum_uploads/ ... r_frei.gif

Hmm, Rotation? (*schmerzverzerrt grins*)
http://www.sturmforum.ch/forum_uploads/ ... r_frei.gif

[Badnerland]

Ja Markus, da waren wieder einige Bilderbuch Hooks dabei. Ich hatte mir gestern Abend noch den Livecast von news9.com (oder so ähnlich) angeschaut. Hammer, was da wieder für "Prachtzellen" unterwegs waren

Glücklicherweise gab es kein Tornado Outbreak im eigentlichen Sinne, auch wenn sich selbst jetzt noch eine beeindruckende Squall mit entsprechenden Windgeschwindigkeiten durch die Staaten frisst. Reports (direkt verlinkt):

http://www.spc.noaa.gov/climo/reports/090210_rpts.html

Für heute dann wieder ein Slight Risk.
11.02.2009

http://www.spc.noaa.gov/products/

Gruss Benni

[Klipsi]

ueber ein Dutzend Todesopfer in Oklahoma

http://www.newsok.com/

http://www.stormtrack.org/forum/showthread.php?t=19444

http://www.stormtrack.org/forum/showthread.php?t=19457

[Bernhard Oker]

Auszug aus einem Livestream zum Tornado von Lone Grove OK mit einem guten Hook Radarbild.
http://www.youtube.com/watch?v=AGtvHrg5-Jg

Gruss
Bernhard