Severe weather possible March 7 to 10?

[RL3AO]

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0357 AM CST TUE MAR 03 2009

VALID 061200Z - 111200Z

THE MEDIUM RANGE MODELS BEGIN THE DAY 4 TO 8 PERIOD WITH A WEST TO
SOUTHWEST FLOW PATTERN ACROSS THE CONUS. THE MODELS ARE IN AGREEMENT
DEVELOPING AN UPPER-LEVEL TROUGH OVER THE WRN STATES FRIDAY AND
MOVING THIS FEATURE ACROSS THE FOUR CORNERS AND ROCKIES REGION
SATURDAY. THE SYSTEM IS PROJECTED INTO THE PLAINS BY SUNDAY AS A
STRONG MID-LEVEL JET EJECTS NEWD INTO THE UPPER MS VALLEY. THIS
PATTERN WOULD RESULT IN LOW-LEVEL MOISTURE RETURN INTO THE SRN
PLAINS AND OZARKS WITH THUNDERSTORMS DEVELOPING ALONG THE MOIST AXIS
SUNDAY AFTERNOON. ATTM...VERTICAL SHEAR PROFILES AND INSTABILITY ON
FORECAST SOUNDINGS APPEAR GREAT ENOUGH FOR AN ORGANIZED SEVERE
THREAT FROM THE SRN PLAINS NNEWD INTO THE MID MS VALLEY SUNDAY AND
SUNDAY NIGHT. HOWEVER...UNCERTAINTIES STILL REMAIN HIGH CONCERNING
THE TIMING OF THE TROUGH AND THE AMOUNT OF INSTABILITY THAT WILL
DEVELOP IN THE WARM SECTOR. WILL NOT OUTLOOK AN AREA ATTM.
HOWEVER...AS CERTAINTY INCREASES...AN OUTLOOK AREA MAY BE NEED TO BE
CONSIDERED IN LATER OUTLOOKS.

BEYOND SUNDAY/DAY 6...MEDIUM RANGE MODEL SOLUTIONS CONTINUE IN
AGREEMENT DEVELOPING A BROAD UPPER-LEVEL TROUGH IN THE SRN STATES
WITH A SOUTHWEST FLOW PATTERN IN PLACE IN THE CNTRL AND ERN U.S.
THIS WOULD PROMOTE CONTINUED MOISTURE RETURN ACROSS THE SRN PLAINS
AND MS VALLEY. CONSIDERING THE AMOUNT OF MID-LEVEL FLOW
FORECAST...SEVERE THUNDERSTORM CLUSTERS WILL BE POSSIBLE ON DAY
7/MONDAY AND DAY 8/TUESDAY. HOWEVER...WILL WAIT TO ESTABLISH RUN TO
RUN CONSISTENCY BEFORE CONSIDERING AN OUTLOOK IN THE SCNTRL U.S.
LATE IN THE DAY 4 TO 8 PERIOD.

..BROYLES.. 03/03/2009

Sunday afternoon

500mb vorticity


850mb winds


Surface dewpoints/MSLP




New 500mb trough moves into SW by Monday evening.

[Ed Mahmoud]

I thought last nights 0Z GFS at tau 144 looked promising.


Well, today is a new day.


Sunday through Tuesday all look potentially interesting, although the GFS is depicting a positively tilted trough, which usually leads to Southwest to West winds up somewhere between 700 and 850 mb, which often caps SE Texas, and we need the rain.



40 minutes to the new Euro.

[RL3AO]

Euro now showing a negative tilt 500mb trough on Sunday.

12z Sunday



0z Monday

[srainhoutx]

Very progressive pattern setting up. I believe we'll see several "episodes". Mid March could offer a significant threat.

[RL3AO]

0z GFS is a lot faster. By Sunday evening, it has the surface low into Southern Ontario.

[Ed Mahmoud]

0z GFS is a lot faster. By Sunday evening, it has the surface low into Southern Ontario.

But another nice chunk of vorticity drops out of Canada on the backside of the mean trough, per the GFS, and again, Tuesday afternoon looks interesting in the Arklatex.

[srainhoutx]

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0359 AM CST WED MAR 04 2009

VALID 071200Z - 121200Z

THE MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT EARLY IN THE DAY 4 TO
8 PERIOD...MOVING AN UPPER-LEVEL TROUGH IN THE ROCKIES ON
SATURDAY/DAY 4 QUICKLY NEWD ACROSS THE GREAT LAKES REGION ON
SUNDAY/DAY 5. SOUTHWEST FLOW DEVELOPS BEHIND THIS SYSTEM ACROSS THE
SRN STATES AS A COLD FRONT DROPS SWD ACROSS THE MID-MS VALLEY AND
SRN PLAINS SUNDAY. SUBSTANTIAL MOISTURE RETURN AHEAD OF THE FRONT
SHOULD BE SUFFICIENT FOR THUNDERSTORM ACTIVITY SUNDAY AND SUNDAY
NIGHT FROM THE SRN PLAINS INTO THE SRN OZARKS. EVEN IF INSTABILITY
REMAINS RELATIVELY WEAK...FORECAST SOUNDINGS SUNDAY SHOW STRONG
ENOUGH VERTICAL SHEAR ASSOCIATED WITH THE ENTRANCE REGION OF A
MID-LEVEL JET FOR AN ORGANIZED SEVERE THREAT. DUE TO MODEL
CONSENSUS...WILL ADD A SEVERE THREAT AREA FROM CNTRL TX NEWD INTO
CNTRL AR FOR SUNDAY AND SUNDAY NIGHT.

THE MEDIUM RANGE MODELS CONTINUE IN AGREEMENT DEVELOPING AN
UPPER-LEVEL TROUGH IN THE WEST MONDAY/DAY 6 WITH SOUTHWEST FLOW IN
PLACE ACROSS THE SCNTRL STATES. THIS WOULD ENCOURAGE MOISTURE RETURN
INTO THE SRN PLAINS WITH INSTABILITY DEVELOPING ALONG THE MOIST AXIS
MONDAY AFTERNOON. SCATTERED THUNDERSTORMS APPEAR POSSIBLE ALONG THIS
AXIS FROM SOUTH TX NWD INTO OK DURING THE DAY AND THROUGH THE
OVERNIGHT PERIOD. IF THIS OCCURS...AN ORGANIZED SEVERE THREAT WOULD
BE POSSIBLE DUE TO THE AMOUNT OF VERTICAL SHEAR FORECAST BY THE
MODELS. HOWEVER...THE VARIANCE OF THE GFS AND ECMWF SOLUTIONS ARE
STILL GREAT ENOUGH TO CAST UNCERTAINTY OVER MONDAYS POTENTIAL.
BEYOND MONDAY...SOUTHWEST FLOW SHOULD CONTINUE ACROSS MUCH OF THE
CNTRL U.S. WITH CONVECTION POSSIBLE FROM THE SRN PLAINS NEWD INTO
THE MID-MS VALLEY. AT THIS RANGE...UNCERTAINTY REMAINS HIGH
CONCERNING THE WEATHER PATTERN AND AMOUNT OF INSTABILITY THAT WILL
BE IN PLACE.

..BROYLES.. 03/04/2009

CLICK TO GET WUUS48 PTSD48 PRODUCT

[Ed Mahmoud]

I am more interested in Tuesday, especially since it is closer to home. A suggestion of some capping in East Texas from thr 700 mb RH and wind direction, but it may be breakable, and the atmosphere looks plenty moist and warm at the 850 mb level.



Low level jet in East Texas of about 30 knots isn't super-duper impressive, but would be sufficient if the instability is there, for some shear.






BTW, the Day 8 (Wednesday) surface map suggests the front hangs up over SE Texas, and although the display resolution (not the model resolution, the Euro is the best, IIRC) is somewhat coarse, it would appear little perturbations in the 500 mb flow would be heading into Texas from Mexico.

[Ed Mahmoud]

12Z GFS shows much needed rain in HOU area Tuesday afternoon, but it looks to be along and behind the front, limiting severe weather potential.


Monday is potentially interesting, especially in North Texas. Although Utah U GFS Most Unstable CAPE looks unimpressive, under 500 J/Kg.

[Ed Mahmoud]

I was fixated on Tuesday from a couple of days ago, but the SPC idea about Sunday being an interesting day in Texas, well, maybe that is why they are the paid professionals and I am a complete amateur.

Looks like the tail end of a stalled front gets active as the next low forms in the Rockies.




The above forecast doesn't look super-favorable for severe weather. But it looked better than Monday.

[RL3AO]

Neither day really hints at large number of tornadic supercells (amateur opinion), but there could be some strong squall lines.

[srainhoutx]

Snipet from HPC today...

EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
144 PM EST WED MAR 04 2009

VALID 12Z SAT MAR 07 2009 - 12Z WED MAR 11 2009



SYSTEM PROGRESSING THROUGH THE WEST AND INTO THE NORTHERN
PLAINS...
IN GENERAL...THE ECMWF SHOWS A SLOWER PROGRESSION WITH THE SYSTEM
EMERGING INTO THE PLAINS LATE IN THE PERIOD /THOUGH IT LIES WITHIN
THE SIGNIFICANT FASTER CLUSTER OF 00Z ECMWF ENSEMBLE SOLUTIONS
USING THE 5400 METER HEIGHT LINE AS A GUIDE AT 500 HPA/ WHILE THE
06Z/12Z GFS CONTINUES TO NOSE AHEAD. THE ECMWF HAS SIGNIFICANTLY
SPED THIS SYSTEM UP DURING ITS PAST 2.5 DAYS OF RUNS...WHICH
CONTINUES THROUGH ITS 12Z RUN...AND ARGUES FOR A QUICKER SOLUTION
THAN THE ECMWF. DURING THE FORECAST PERIOD...THE HEAVIEST
PRECIPITATION APPEARS TO BE FOCUSED FROM THE SOUTHERN PLAINS/TEXAS
INTO THE MID-MISSISSIPPI VALLEY AND OHIO VALLEY. THUNDERSTORMS
ACROSS THE ARKLATEX COULD BE SEVERE ON SUNDAY/MONDAY PER THE MOST
EARLY MORNING OUTLOOK FROM THE STORM PREDICTION CENTER.
ROTH

[RL3AO]

Could be some storms over central/eastern Oklahoma on Saturday. Nothing super impressive.

[srainhoutx]

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0400 AM CST THU MAR 05 2009

VALID 081200Z - 131200Z

THE MEDIUM RANGE MODELS BEGIN THE DAY 4 TO 8 PERIOD WITH A
PROGRESSIVE UPPER-LEVEL TROUGH OVER THE GREAT PLAINS. THIS FEATURE
MOVES EWD INTO THE GREAT LAKES REGION AS ANOTHER UPPER-LEVEL TROUGH
DEVELOPS IN THE WRN STATES SUNDAY. ON SUNDAY/DAY 4...THE MODELS
FORECAST A LARGE AREA OF CONVECTION FROM THE UPPER-LEVEL TROUGH IN
THE MID TO UPPER MS VALLEY SSWWD INTO THE SRN PLAINS AND OZARKS. TWO
AREAS LOOK TO HAVE POTENTIAL FOR SEVERE THUNDERSTORMS. THE FIRST
EXISTS NEAR THE UPPER-LEVEL TROUGH OVER THE LOWER OH VALLEY EARLY IN
THE DAY. IN SPITE OF STRONG VERTICAL SHEAR AND STRONG LARGE-SCALE
ASCENT...INSTABILITY IN THIS AREA SHOULD BE QUITE WEAK. THE SECOND
AREA OVER THE SRN PLAINS AND OZARKS WILL BE IN AN AREA OF WEAKENING
LOW-LEVEL FLOW. HOWEVER...FORECAST SOUNDINGS SHOW ENOUGH INSTABILITY
WITH MODERATE VERTICAL SHEAR AND 60+ SFC DEWPOINTS. THIS SHOULD BE
SUFFICIENT FOR A SEVERE THREAT ALONG THE FRONT FROM ERN TX NEWD INTO
CNTRL AR ON SUNDAY AFTERNOON.

BEYOND SUNDAY/DAY 4...THE MEDIUM RANGE MODELS ARE IN GENERAL
AGREEMENT...BRINGING AN UPPER-LEVEL TROUGH INTO THE INTERMOUNTAIN
WEST AND FOUR CORNERS REGION. SOUTHWEST FLOW IN PLACE ACROSS THE SRN
PLAINS SHOULD ENCOURAGE MOISTURE RETURN AND AN AXIS OF INSTABILITY
SHOULD BE IN PLACE BY MONDAY AFTERNOON/DAY 5 FROM CNTRL TX INTO OK
AND AR. THE GFS AND ECMWF ARE ALSO IN AGREEMENT DEVELOPING
THUNDERSTORMS ALONG THE WRN EDGE OF THE INSTABILITY AXIS MONDAY
AFTERNOON. THE MODELS ARE IN FAIRLY GOOD AGREEMENT WITH STRONG
VERTICAL SHEAR AND A WELL-FOCUSED LOW-LEVEL JET SUGGESTING A
SUBSTANTIAL SEVERE THREAT COULD EXIST OVER MUCH OF THE SRN PLAINS
MONDAY AND MONDAY NIGHT.

INSTABILITY SHOULD CONTINUE TO BE IN PLACE ACROSS A RELATIVELY LARGE
WARM SECTOR TUESDAY/DAY 5 AND WEDNESDAY/DAY 6. IN ADDITION...THE
MODELS DEVELOP A LARGE AREA OF CONVECTION TUESDAY NIGHT ALONG A COLD
FRONT. HOWEVER...THE TIMING AND LOCATION FROM THE GFS AND ECMWF ARE
OUT OF PHASE WITH THE GFS MUCH FURTHER EAST. FOR THIS REASON WILL
NOT OUTLOOK A SEVERE THREAT AREA BEYOND DAY 5.

..BROYLES.. 03/05/2009

[Ed Mahmoud]

THE MODELS ARE IN FAIRLY GOOD AGREEMENT WITH STRONG VERTICAL SHEAR AND A WELL-FOCUSED LOW-LEVEL JET SUGGESTING A
SUBSTANTIAL SEVERE THREAT COULD EXIST OVER MUCH OF THE SRN PLAINS MONDAY AND MONDAY NIGHT.

Hmmmm, interesting...

[srainhoutx]

THE MODELS ARE IN FAIRLY GOOD AGREEMENT WITH STRONG VERTICAL SHEAR AND A WELL-FOCUSED LOW-LEVEL JET SUGGESTING A
SUBSTANTIAL SEVERE THREAT COULD EXIST OVER MUCH OF THE SRN PLAINS MONDAY AND MONDAY NIGHT.

Hmmmm, interesting...

Look what the HPC Prelim is offering just beyond on Tuesday-Thursday...snipet...

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
900 AM EST THU MAR 05 2009

VALID 12Z MON MAR 09 2009 - 12Z THU MAR 12 2009

...EAST-CENTRAL US...

MODEL AND ENSEMBLES HAVE SHOWN ABOVE NORMAL SOLUTION SPREAD OVER
THE PAST COUPLE OF DAYS WITH THE TIMING/STRENGTH OF SRN STREAM
SHORTWAVE TROUGH ENERGY EJECTING OUT FROM THE EAST-CENTRAL US IN
THE SHORT RANGE TO THE VICINITY OF THE NERN US BY MON.
CONSIDERING TIMING AND STRENGTH UNCERTAINIES AND THE SMALL SCALE
NATURE OF THE FEATURES...IT SEEMS SUCH ROBUST MID-UPPER LEVEL
TROUGH AMPLIFICATION AND LOW GENESIS AS PER NRN STREAM PHASING IN
THE OUTLIER 00 UTC ECMWF WOULD BE UNLIKELY. INSTEAD PREFER A LESS
PHASED SOLUTION CLUSTER CLOSER TO GUIDANCE FROM EITHER THE 00/06
UTC GFS OR 00 UTC UKMET.

UPSTREAM...AMPLE WRN US MID-UPPER LEVEL TROUGH ENERGY EJECTING OUT
INTO THE PLAINS THEN EAST-CENTRAL US IN THE WAKE OF THE LEAD ERN
US SYSTEM SEEMS TO STRONGLY FAVOR DEVELOPMENT OF A ANOTHER POTENT
SURFACE LOW/FRONTAL SYSTEM TUE-THU THAT WILL ACT TO FOCUS
MOISTURE/PCPN... INCLUDING A THREAT FOR LEAD CONVECTION AND HEAVY
SNOW ON THE NW PERIPHERY OF THE SYSTEM AS COLD CANADIAN AIR SLAMS
SOUTHWARD THROUGH THE CENTRAL US.

Probably more for the Winter Topic, but offers the strength of the Surface Low that will no doubt play a role in some severe weather Mid Week.

[Ed Mahmoud]

If- if- the Euro is right, Tuesday will be the biggest severe weather day, Oklahoma, Arkansas and Missouri, then maybe points East, based on 850 mb wind direction and speed compared to 500 mb winds. I can't tell what Euro thinks the instability will be, but 850 mb temps are above 50ºF well into Missouri with high relative humidity.





The GFS Tuesday is a bit further East, eastern Texas to maybe Southern Indiana.

[Ed Mahmoud]

Is the GFS suggesting a dry line/warm front intersection, an area of convergence, Sunday near/just East of the DFW area, as the main surface low develops in the Rockies?



A boundary intersection (a little extra vorticity) with 1000 Joule/Kg MU-Cape along it might provide some interesting weather.



Modifying the above image URL to Hour 132 suggests strong storms along the front from SW Missouri to Texas on Tuesday.

Back to Sunday, looking at NIU Storm Machine Soundings, helicity looks somewhat meager, on the order of 130 J/Kg in the 'warm sector', so any spin ups probably would need the extra vorticity a boundary merger could provide.

If the GFS is in the correct ballpark. Looking at the WRF and Canadian on the PSU e-Wall, there appears to be some spread between the models.

[Ed Mahmoud]

Snip of NWS FWD AFD

THE SURFACE LOW WILL FINALLY MOVE OFF TO THE EAST AS IT GETS
PICKED UP AS AN UPPER TROUGH SWINGS THROUGH THE PLAINS. A WEAK
COLD FRONT ASSOCIATED WITH THE LOW WILL BEGIN TO MOVE THROUGH THE
CWA SUNDAY BUT WILL STALL ACROSS THE REGION AS UPPER DYNAMICS PASS
TOO FAR NORTH. THE EXACT POSITIONING OF THE BOUNDARY WILL BE FINE
TUNED IN THE NEXT COUPLE OF DAYS BUT CURRENT MODELS PLACE THE
BOUNDARY AROUND THE DFW METROPLEX. SHOWERS AND THUNDERSTORMS WILL
DEVELOP ALONG THE BOUNDARY SUNDAY AFTERNOON. SOME STRONG STORMS
WILL BE POSSIBLE AS SBCAPE EXCEEDS 1000 J/KG BUT WITH WEAK TO
MODERATE SHEAR...DO NOT ANTICIPATE ORGANIZED SEVERE CONVECTION.

BY MONDAY...EXTENDED RANGE MODELS BEGIN TO DIVERGE. THE BOUNDARY
WILL LIFT BACK TO THE NORTH AS A WARM FRONT. THE ECMWF HAS THE
BOUNDARY ALONG THE RED RIVER MONDAY MORNING WHILE THE GFS PLACES IT
IN OKLAHOMA. SEVERE WEATHER MONDAY WILL BE DEPENDANT ON THE EXACT
POSITIONING OF THE BOUNDARY. DEEP AND LOW LEVEL SHEAR WILL BE MODERATE TO STRONG MONDAY WITH SBCAPE VALUES AROUND 1000 J/KG
LEADING TO STRONG TO SEVERE STORMS IN THE WARM SECTOR.

[CrazyC83]

Round 1 shouldn't be much, but I agree March 9-11 should be interesting.