Radtechwxman Posted November 17, 2011 Share Posted November 17, 2011 ZCZC SPCSWOD48 ALL ACUS48 KWNS 170956 SPC AC 170956 DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0356 AM CST THU NOV 17 2011 VALID 201200Z - 251200Z ...DISCUSSION... MEDIUM RANGE MODELS IN GENERAL AGREEMENT THROUGH DAYS 4-5 /SUN. AND MON. NOV. 20 AND 21/...AS AMPLIFICATION OF THE SRN STREAM FLOW FIELD -- OVER ROUGHLY THE SRN HALF OF THE U.S. -- OCCURS. A SHORT-WAVE TROUGH/LOW OFF THE CA COAST AT THE START OF THE PERIOD /EARLY DAY 4/ IS FORECAST TO CONTINUE SEWD ALONG THE COAST AND THEN BEGIN AN EWD TURN INTO THE SWRN U.S./NWRN MEXICO LATE. AS THIS OCCURS...SHORT-WAVE RIDGING DOWNSTREAM INTO THE S CENTRAL U.S. SHOULD LIMIT CONVECTIVE POTENTIAL ALONG A REMNANT COLD FRONT LINGERING ACROSS THE SRN PLAINS AND VICINITY. HOWEVER...AS THE SYSTEM MOVES ENEWD ACROSS THE SRN ROCKIES TOWARD THE SRN AND CENTRAL PLAINS DAY 5...HEIGHT FALLS WILL SPREAD ACROSS TX/ATOP THE FRONTAL ZONE. WITH STEEPENING LAPSE RATES ALOFT AND FAVORABLY MOIST LOW-LEVEL AIRMASS S OF THE FRONT...HEATING/DESTABILIZATION WILL LIKELY LEAD TO STORM DEVELOPMENT. WHILE CAPPING SHOULD HINDER DEVELOPMENT WITH SEWD EXTENT -- INTO SRN AND ERN TX...STORM INITIATION SEEMS LIKELY FARTHER W/NW. WITH VERY STRONG SWLY FLOW ALOFT -- SPREADING EWD IN CONJUNCTION WITH THE ADVANCING SHORT-WAVE TROUGH -- ATOP VEERING LOW-LEVEL WINDS...SHEAR IS PROGGED TO BECOME FAVORABLE FOR SUPERCELLS. PRESUMING MODEL FORECASTS REMAIN CONSISTENT WITH RESPECT TO EVOLUTION OF THIS WEATHER SYSTEM...THE THREAT FOR A MORE SUBSTANTIAL SEVERE EVENT SHOULD EVOLVE -- THUS WARRANTING THE INTRODUCTION OF A THREAT AREA FOR DAY 5 /MON. NOV. 21/ ACROSS PARTS OF NRN/NWRN AND INTO CENTRAL TX. BEYOND DAY 5...MODEL DIVERGENCE INCREASES RAPIDLY -- WITH DIFFERING DEPICTIONS OF THE ADVANCE OF THE SRN STREAM SHORT-WAVE TROUGH. THUS...LOW CONFIDENCE PRECLUDES INCLUSION OF ANY THREAT AREAS LATER IN THE PERIOD. ..GOSS.. 11/17/2011 CLICK TO GET WUUS48 PTSD48 PRODUCT Link to comment Share on other sites More sharing options...
Radtechwxman Posted November 17, 2011 Author Share Posted November 17, 2011 i havent had a lot of time to look into the models but GFS is showing a potent low amplitude shortwave trough. looks to be taking on a negative tilt as it ejects from the SW. 120knt speed max at 250mb and a 80knt speed max at 500mb rounding the base of the trough by 18z as seen as on the 12z run of GFS today. GFS is showing good moisture return and some good CAPE values for this time of year. models really arent showing any well developed sfc low pressure areas atm though. def will have my eye on it Link to comment Share on other sites More sharing options...
brettjrob Posted November 17, 2011 Share Posted November 17, 2011 Fairly surprised to see this outlook drawn so early. There doesn't appear to be much model consensus supporting a substantial event at the moment. I'd like to see the trough a bit more amplified, especially for a cold-season event. Link to comment Share on other sites More sharing options...
Radtechwxman Posted November 17, 2011 Author Share Posted November 17, 2011 Fairly surprised to see this outlook drawn so early. There doesn't appear to be much model consensus supporting a substantial event at the moment. I'd like to see the trough a bit more amplified, especially for a cold-season event. yea i agree man. even though it isnt amplified much, the speed shear is pretty impressive. with stronger jet stream dynamics this time of year, it doesnt take much to set off a sig severe weather episode. what i would really like to see is a well developed sfc low ahead of the trough axis. if i recall right, GFS was looking quite disorganized for quite some time last week for that big event on monday with the EF4 in SW Oklahoma. we will just have to wait and see if models agree better down the road. i want to see what NAM shows once it is in its range. wish i had access to ECM Link to comment Share on other sites More sharing options...
Jim Martin Posted November 18, 2011 Share Posted November 18, 2011 Good looking cape values here. Between 1,500 & 2,000 units in the heart of Texas for Monday. Link to comment Share on other sites More sharing options...
Radtechwxman Posted November 18, 2011 Author Share Posted November 18, 2011 i am liking those cape values. if that was realized, that would def be sufficient enough for severe weather given the favorable wind profiles being forecasted Link to comment Share on other sites More sharing options...
Jim Martin Posted November 18, 2011 Share Posted November 18, 2011 Thought I throw this out while were talking here. Fort Worth sounding here for 6pm cst Monday. Helicity is there. Chances of supercells fairly high also. Link to comment Share on other sites More sharing options...
andyhb Posted November 18, 2011 Share Posted November 18, 2011 00z GFS has a rather broad warm sector with >1000 J/kg SBCAPE and mid 60's sfc dews across a large portion of Texas. Also to be noted that the NAM already has a substantially stronger LLJ than the GFS even only by 12z Monday... I'm thinking a Day 4 area may be strongly considered. Link to comment Share on other sites More sharing options...
Radtechwxman Posted November 18, 2011 Author Share Posted November 18, 2011 00z GFS has a rather broad warm sector with >1000 J/kg SBCAPE and mid 60's sfc dews across a large portion of Texas. Also to be noted that the NAM already has a substantially stronger LLJ than the GFS even only by 12z Monday... I'm thinking a Day 4 area may be strongly considered. I totally agree. this system has a lot of potential. reminds me a lot of how the models behaved before the big severe event last monday. there was only a 1008mb low associated with the nov 7th outbreak. timing of the speed max's will be crucial. 0z GFS had the speed max at 250mb and 500mb rounding the base of the trough at 18z. once those features are able to round the base, they usually speed up quite quickly. Link to comment Share on other sites More sharing options...
Srain Posted November 18, 2011 Share Posted November 18, 2011 DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0355 AM CST FRI NOV 18 2011 VALID 211200Z - 261200Z ...DISCUSSION... SHORTWAVE TROUGH NOW OVER ALEUTIANS...DISCUSSED IN DAY-3 OUTLOOK...IS EXPECTED TO MOVE ACROSS PORTIONS AZ/NWRN MEX EARLY DAY-4...ROUGHLY 21/12Z-21/18Z TIME FRAME. DESPITE SOME STRENGTH/TIMING UNCERTAINTIES...PROGS ARE FAIRLY SIMILAR THROUGH MID-LATE DAY-4. TROUGH SHOULD MOVE ACROSS NM AND CHIHUAHUA AROUND 22/00Z THEN EXTEND FROM OK TO FAR W TX BY 22/12Z. RESULTANT SFC LOW DEVELOPMENT IS FCST ALONG STALLED FRONT...MOVING NEWD OVER CENTRAL/N-CENTRAL TX AND PERHAPS SERN OK. RETURN OF MID-60S SFC DEW POINTS BENEATH STRENGTHENING VERTICAL SHEAR SHOULD SUPPORT POTENTIAL FOR CONCENTRATION OF SVR NEAR THAT FRONT AND CYCLONE TRACK. SVR AREA IS KEPT...BUT SHIFTED EWD IN DEFERENCE TO FASTER CONSENSUS TIMING OF FEATURES COMPARED TO PRIOR GUIDANCE. BY DAY-5/22ND-23RD...DIFFERENCES BECOME PRONOUNCED WITH THIS SYSTEM BETWEEN SPECTRAL/ECMWF...AND AMONGST MREF MEMBERS. CONSIDERABLE UNCERTAINTY EXISTS ATTM REGARDING BOTH PHASE SPEED AND AMPLITUDE OF MID-UPPER WAVE...AND RESULTANT POSITIONING/STRENGTH OF FAVORABLE LOW-LEVEL MASS FIELDS. THEREFORE...ALTHOUGH SOME PORTION OF MID-SOUTH/DELTA/TN VALLEY REGIONS PROBABLY WILL NEED AT LEAST 15%/SLGT-RISK AREA EVENTUALLY...IT IS TOO SOON TO ASSIGN UNCONDITIONAL 30% D5 LINE ATTM. ..EDWARDS.. 11/18/2011 Link to comment Share on other sites More sharing options...
Ed Lizard Posted November 18, 2011 Share Posted November 18, 2011 New GFS soundings for Dallas area look more like heavy rain than tornadoes... Link to comment Share on other sites More sharing options...
Jim Martin Posted November 18, 2011 Share Posted November 18, 2011 Not the greatest Significant Tornado Parameter numbers, but they are there. Link to comment Share on other sites More sharing options...
Radtechwxman Posted November 18, 2011 Author Share Posted November 18, 2011 we are in the time frame where models really do a lot of bouncing around. does anyone know when the system comes on shore? i would like to see models after it has been sampled. also during changing seasons when the jet stream goes through dramatic changes, esp with La Nina in place, the models seem to take time to line up on a solution. Link to comment Share on other sites More sharing options...
andyhb Posted November 18, 2011 Share Posted November 18, 2011 The weakness of the LLJ may prevent this from becoming something more significant, although the CAPE levels/H5 profiles look nice. Although, of note, Dr. Forbes already has N. Texas at a 5 on the TOR:CON for Monday. Link to comment Share on other sites More sharing options...
brettjrob Posted November 19, 2011 Share Posted November 19, 2011 Although, of note, Dr. Forbes already has N. Texas at a 5 on the TOR:CON for Monday. That surprises me as much as the SPC outlook. I can't recall many (if any) tornado events in this region with such a "saggy" boundary and significantly colder air to the N. Furthermore, low-level wind profiles look flat-out unimpressive at this time. Both of these issues are related (to an extent) to the fact that this trough simply isn't very amplified and is weakening as it progresses through the Desert SW, in stark contrast to the 11/07 event. IMHO, it will take some significant last-minute changes in order to see a threat that's in the same league as that of two weeks ago. Link to comment Share on other sites More sharing options...
David Reimer Posted November 19, 2011 Share Posted November 19, 2011 That surprises me as much as the SPC outlook. I can't recall many (if any) tornado events in this region with such a "saggy" boundary and significantly colder air to the N. Furthermore, low-level wind profiles look flat-out unimpressive at this time. Both of these issues are related (to an extent) to the fact that this trough simply isn't very amplified and is weakening as it progresses through the Desert SW, in stark contrast to the 11/07 event. IMHO, it will take some significant last-minute changes in order to see a threat that's in the same league as that of two weeks ago. I agree with you on the tornado threat. Low level instability is fairly low and while there is turning with height, the low level jet looks fairly weak for both Sunday and Monday. Honestly, right now I would think the highest tornado threat relative to both days would be on Sunday, but then again we would need organized convection to form. Monday could be a busy day in terms of hail and wind reports across North Texas, but I'm not seeing the tornado threat. If there was going to be any sustained tornado threat, I would expect it to be closest to the warm front and any boundaries that may be in place. As of now, I'm not impressed and neither is the SREF. Link to comment Share on other sites More sharing options...
brettjrob Posted November 19, 2011 Share Posted November 19, 2011 I agree with you on the tornado threat. Low level instability is fairly low and while there is turning with height, the low level jet looks fairly weak for both Sunday and Monday. Honestly, right now I would think the highest tornado threat relative to both days would be on Sunday, but then again we would need organized convection to form. Monday could be a busy day in terms of hail and wind reports across North Texas, but I'm not seeing the tornado threat. If there was going to be any sustained tornado threat, I would expect it to be closest to the warm front and any boundaries that may be in place. As of now, I'm not impressed and neither is the SREF. Strongly agree with that -- I was eyeing Sunday, too, looking at the NAM earlier. Unfortunately, the lack of upper-level support and relatively warm mid-level temperatures well ahead of the incoming trough are mitigating factors, despite excellent moisture in place. Will keep an eye on both days. Link to comment Share on other sites More sharing options...
andyhb Posted November 19, 2011 Share Posted November 19, 2011 Considerably stronger LLJ by 00z Monday on the 00z GFS. Link to comment Share on other sites More sharing options...
Radtechwxman Posted November 19, 2011 Author Share Posted November 19, 2011 Considerably stronger LLJ by 00z Monday on the 00z GFS. i def agree. looks better than eariler. still room for much improvement though. gotta watch for trends. i wanna see what models do once the system is sampled by the upper air networks Link to comment Share on other sites More sharing options...
andyhb Posted November 19, 2011 Share Posted November 19, 2011 i def agree. well of course you agree it's right there on the models... Slight risk for Sunday. DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1154 PM CST FRI NOV 18 2011 VALID 201200Z - 211200Z ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS N-CENTRAL TX TO SWRN AR... ...SYNOPSIS... IN MID-UPPER LEVELS...STG SHORTWAVE TROUGH NOW OVER PAC NW IS FCST TO DEAMPLIFY AND EJECT ACROSS UPPER GREAT LAKES BY START OF PERIOD. AS THIS OCCURS...SFC FRONTAL ZONE -- NOW ANALYZED FROM WI TO S-CENTRAL NEB AND NERN CO -- WILL SURGE SEWD ACROSS UPPER MIDWEST AND CENTRAL PLAINS DAY-1...REACHING FROM SRN ONT SWWD ACROSS SRN IL...OZARKS AND CENTRAL/SRN OK BY 20/12Z. FRONT SHOULD DECELERATE W OF MS RIVER UNDER ESSENTIALLY PARALLEL/SWLY FLOW ALOFT...SAGGING SWD TO VICINITY EVV-FSM-MWL LINE AND WWD OVER TX SOUTH-PLAINS REGION BY 21/00Z. WITHIN 12 HOURS...FRONT SHOULD BECOME QUASISTATIONARY FROM OH VALLEY SWWD OVER N-CENTRAL AND W-CENTRAL TX. MEANWHILE...ANOTHER MID-UPPER LEVEL SHORTWAVE TROUGH -- NOW EVIDENT IN MOISTURE CHANNEL IMAGERY OVER NERN PAC NEAR 48N140W -- SHOULD DIG SEWD ACROSS PAC OFFSHORE WATERS. TROUGH SHOULD MOVE ASHORE NRN/CENTRAL BAJA BY END OF PERIOD. ...N-CENTRAL TX TO SWRN AR... BROAD REGIME OF LOW-LEVEL WAA AND MOISTURE TRANSPORT IS FCST TO DEVELOP OVER SRN PLAINS NEWD ACROSS OH VALLEY REGION ON BOTH SIDES OF SFC FRONT. ELEVATED BUOYANCY...AND ISENTROPIC/FRONTOGENETIC ASCENT TO LEFT WILL SUPPORT EPISODES OF WIDELY SCATTERED TSTMS N OF FRONT THROUGHOUT PERIOD. GREATEST SVR POTENTIAL WILL ACCOMPANY WIDELY SCATTERED SFC-BASED TSTMS INVOF FRONT DURING AFTERNOON/EARLY EVENING...FROM N-CENTRAL TX TO SWRN AR. MOISTURE RETURN...WITH SFC DEW POINTS REACHING MID-60S F IN WARM SECTOR...SHOULD COMBINE WITH SFC DIABATIC HEATING TO WEAKEN MLCINH AND OFFSET MODEST MID-UPPER LEVEL LAPSE RATES. RESULT BY LATE AFTERNOON SHOULD BE 1500-2000 J/KG MLCAPE OVER CENTRAL/N-CENTRAL TX...GRADING TO 500-1000 J/KG OVER WRN AR...BASED ON MODIFIED NAM/ETA-KF FCST SOUNDINGS. NEAR-SFC WINDS WILL BE LIGHT...LIMITING HODOGRAPH SIZE...HOWEVER DEEP-LAYER BULK SHEAR SHOULD BE SUFFICIENT TO SUPPORT SOME ORGANIZED SVR POTENTIAL...WITH PROGGED EFFECTIVE SHEAR MAGNITUDES 45-55 KT. MAIN CONCERN FOR SVR POTENTIAL HAS BEEN CONVECTIVE COVERAGE/DURATION...ESPECIALLY GIVEN LACK OF APPRECIABLE MID-UPPER PERTURBATIONS. ALL MEMBERS OF LATEST SREF PACKAGE EXCEPT FOR ETA-BMJ RESPOND TO WEAK CINH AND NEAR-FRONTAL LIFT VIA SUSTAINED CONVECTIVE PRECIP DURING 20/21Z-21/03Z TIME FRAME...OVER SOME PORTION N-CENTRAL TX NEWD TO SERN OK...MOVING NEWD DURING EVENING. ..EDWARDS.. 11/19/2011 Link to comment Share on other sites More sharing options...
andyhb Posted November 19, 2011 Share Posted November 19, 2011 DAY 3 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0222 AM CST SAT NOV 19 2011 VALID 211200Z - 221200Z ...THERE IS A SLGT RISK OF SVR TSTMS PORTIONS W-CENTRAL/SW TX TO SWRN AR... ...SYNOPSIS... NERN PAC TROUGH...DISCUSSED IN DAY-2 OUTLOOK...IS EXPECTED OVER CENTRAL/NRN BAJA AND LOWER CO RIVER VALLEY REGION AT BEGINNING OF PERIOD. TROUGH SHOULD MOVE ENEWD TO WRN NM AND NRN CHIHUAHUA BY 22/00Z...WEAKENING SOMEWHAT BUT STILL A HIGH-AMPLITUDE PERTURBATION AT THAT TIME. DURING LATTER HALF OF PERIOD...TROUGH SHOULD ACCELERATE ENEWD ACROSS SRN HIGH PLAINS AND ASSUME PRONOUNCED POSITIVE TILT. BY 22/12Z...OPERATIONAL NAM AND SREF CONSENSUS INDICATE TROUGH FROM WRN OK SWWD ACROSS TRANS-PECOS REGION OF W TX. SPECTRAL IS SLIGHTLY FASTER IN AGREEMENT WITH OLDER ECMWF RUN...BUT WITH ONLY MESOSCALE DIFFERENCES IN BOTH MID-UPPER POSITIONING AND LOW-LEVEL FEATURES. AT SFC...MID-LATE AFTERNOON DRYLINE SHOULD INTERSECT INITIALLY QUASISTATIONARY FRONTAL ZONE OVER W TX...PERHAPS NEAR MAF...EXTENDING SWD ACROSS RIO GRANDE INTO SERRANIAS DEL BURRO REGION OF NRN MEX. FRONTAL-WAVE LOW IS EXPECTED TO DEVELOP DURING 22/00Z-22/06Z ACROSS W-CENTRAL/N-CENTRAL TX...PERHAPS INITIALLY AT DRYLINE/FRONT TRIPLE POINT. LOW SHOULD MOVE NEWD ACROSS SERN OK TO NWRN/N-CENTRAL AR OVERNIGHT. IN ITS WAKE...BAROCLINIC ZONE SHOULD MOVE SEWD ACROSS SW TX AND HILL COUNTRY...WHILE BOUNDARY NE OF LOW REMAINS QUASISTATIONARY EXCEPT FOR SLGT NWD MOTION IMMEDIATELY AHEAD OF CYCLONE. ...SRN PLAINS TO AR... ANOTHER ROUND OF STG-SVR TSTMS IS LIKELY INVOF SFC FRONTAL ZONE...BUT WITH GREATER COVERAGE LIKELY IN FACE OF STRENGTHENING OF BOTH LARGE-SCALE ASCENT AND DEEP-LAYER SHEAR AHEAD OF APCHG MID-UPPER TROUGH. CONVECTION SHOULD FORM ON BOTH SIDES OF FRONT DURING AFTERNOON/EVENING...AS WELL AS NEAR DRYLINE...INCREASING IN COVERAGE WITH TIME. GIVEN LIKELY STRENGTH OF BAROCLINIC ZONE...LARGE HAIL IS GREATEST THREAT OVER POSTFRONTAL STABLE LAYER...WHILE FULL RANGE OF SVR MAY OCCUR ALONG AND S OF FRONT. FCST SOUNDINGS SUGGEST COMBINATION OF FRONTAL LIFT AND SFC DIABATIC HEATING...WITH MOIST-SECTOR DEW POINTS 60S F...WILL OVERCOME CINH AND SUPPORT TSTM DEVELOPMENT. SFC WINDS SHOULD BACK AND INCREASE SOMEWHAT RELATIVE TO PRIOR DAY...WITH LARGER LOW-LEVEL HODOGRAPHS AND COMPARABLE DEEP-LAYER SHEAR MAGNITUDES. THEREFORE...SUPERCELLS AND BOWS WILL BE POSSIBLE. GREATEST CONCENTRATION OF CONVECTIVE/SVR THREAT SHOULD BE VERY NEAR FRONT. PEAK-PROBABILITY CORRIDOR REFLECTING THAT SCENARIO IS BASED ON CONSENSUS OF SREF/OPERATIONAL FRONTAL POSITIONS DURING 21/21Z-22/03Z TIME FRAME...AND MAY NEED TO BE ADJUSTED SOMEWHAT N OR S BASED ON ANY SUBSTANTIAL SHIFTS IN EXPECTED LOCATION OF BOUNDARY BETWEEN NOW AND THEN. AT LEAST MRGL SVR POTENTIAL MAY EXTEND ENEWD ACROSS PORTIONS MID-SOUTH REGION IN LOW-LEVEL WAA/MOISTURE-TRANSPORT PLUME...ALONG/AHEAD OF SFC FRONT. HOWEVER...NEITHER LAPSE RATES NOR LOW-LEVEL SHEAR WILL BE AS STG AS CLOSER TO MID-UPPER WAVE...OVER CATEGORICAL RISK AREA. ..EDWARDS.. 11/19/2011 Link to comment Share on other sites More sharing options...
David Reimer Posted November 19, 2011 Share Posted November 19, 2011 My interest for Sunday and Monday ramped up with the 0Z model runs. It looks like the NAM has increased the low level jet on both Sunday and Monday by around 5 knots, resulting in a sustained southeasterly flow of about 25-30 knots, increasing to 30-35 knots on Monday. Fred Gossage pointed out to me that the models did a rather poor job of handling the low level jet speeds during the southeast tornado event a few days ago. I'm going to be keeping a very close eye on this event, as I'm beginning to suspect that the threat could be higher then I originally indicated yesterday. Either way, it looks like a busy severe weather event for Sunday and Monday across my coverage area. I'm planning to chase both Sunday and Monday. Who knows, it may be a good time to test my new Vantage Vue I have mounted on my vehicle. Anyway, I've got my thoughts posted on the Texas Storm Chasers website. If you're interested, you can check it out at http://texasstormchasers.com/?p=4724 Link to comment Share on other sites More sharing options...
andyhb Posted November 19, 2011 Share Posted November 19, 2011 My interest for Sunday and Monday ramped up with the 0Z model runs. It looks like the NAM has increased the low level jet on both Sunday and Monday by around 5 knots, resulting in a sustained southeasterly flow of about 25-30 knots, increasing to 30-35 knots on Monday. Fred Gossage pointed out to me that the models did a rather poor job of handling the low level jet speeds during the southeast tornado event a few days ago. I'm going to be keeping a very close eye on this event, as I'm beginning to suspect that the threat could be higher then I originally indicated yesterday. Either way, it looks like a busy severe weather event for Sunday and Monday across my coverage area. I'm planning to chase both Sunday and Monday. Who knows, it may be a good time to test my new Vantage Vue I have mounted on my vehicle. Anyway, I've got my thoughts posted on the Texas Storm Chasers website. If you're interested, you can check it out at http://texasstormchasers.com/?p=4724 Thought about this as well. Excellent analysis on the website and good luck, you certainly nailed it last event. Link to comment Share on other sites More sharing options...
Ed Lizard Posted November 19, 2011 Share Posted November 19, 2011 The NAM looks better to me for severe in the general DFW area, a well defined boundary, and good helicity. Might make up for meager low level instability. Whether the NAM is right, I sure don't know. Link to comment Share on other sites More sharing options...
David Reimer Posted November 19, 2011 Share Posted November 19, 2011 As I discussed earlier this morning, the NAM has continued to slowly increase the strength of the Low Level Jet for both Sunday and Monday. Here's two graphics showing 850 millibars at 6 PM on Sunday and Monday. I'm not going to do an in-depth analysis until tonight's 0Z model suites are in, but I am growing more impressed with the potential for Severe Weather tomorrow, especially if the models are underestimating the amount of instability as they tend to do. The SREF is showing a good chance of convection underway by about 4 PM tomorrow with the D/FW Metroplex likely having some issues between 6 and 9 PM. The significant tornado ingredients parameter values have increased for Sunday, but I'm not comfortable discussing the tornado potential until we have higher resolution guidance depicting if we'll have any convection developing south of the warm front. If we do, I wouldn't be surprised to see a brief tornado tomorrow, especially with any warm front interactions. I'm expecting a decent damaging wind threat tomorrow and especially on Monday. I'm planning on doing another discussion tonight, but it does appear the next two days are going to be quite active in terms of severe weather reports. Link to comment Share on other sites More sharing options...
Jim Martin Posted November 19, 2011 Share Posted November 19, 2011 12z GFS Sounding for Fort Worth at 6pm Monday cst. The severe weather parameters have ramped up here. Link to comment Share on other sites More sharing options...
brettjrob Posted November 19, 2011 Share Posted November 19, 2011 Interestingly, the hodo on that GFS sounding looks reminiscent of the 00z OUN sounding on November 7. If instability (especially owing to low-level lapse rates) is greater than indicated on that image, things could get interesting. It's probably worth noting that both instability and low-level shear have been generally underestimated by the short-range models lately. EDIT: Tomorrow is beginning to impress me, as well, conditional upon surface-based initiation south of the boundary. A sampling of 18z NAM forecast soundings in the Metroplex reveals sufficient thermodynamics with impressive vertical shear profiles by 00z Mon for supercells. This is especially true if you back and strengthen near-surface winds a bit, which, again, has been a bias of the NAM this year. Link to comment Share on other sites More sharing options...
chase_stormz Posted November 19, 2011 Share Posted November 19, 2011 it definitely is looking better on the NAM. Monday is starting to impress me more, and I really am impressed by that sounding for the Fort Worth area. Link to comment Share on other sites More sharing options...
David Reimer Posted November 19, 2011 Share Posted November 19, 2011 Interestingly, the hodo on that GFS sounding looks reminiscent of the 00z OUN sounding on November 7. If instability (especially owing to low-level lapse rates) is greater than indicated on that image, things could get interesting. It's probably worth noting that both instability and low-level shear have been generally underestimated by the short-range models lately. EDIT: Tomorrow is beginning to impress me, as well, conditional upon surface-based initiation south of the boundary. A sampling of 18z NAM forecast soundings in the Metroplex reveals sufficient thermodynamics with impressive vertical shear profiles by 00z Mon for supercells. This is especially true if you back and strengthen near-surface winds a bit, which, again, has been a bias of the NAM this year. Completely unrelated to the weather side of the discussion, but if you're chasing in the metroplex either days be sure to avoid I-635 from Interstate 35E over to US-75. There's a major reconstruction going on and it's usually a pretty nightmarish corridor in terms of traffic. The PGBT is a good alternative. Of course, if this all ends up happening on Monday during rush hour, it's going to make navigating the metroplex about ten times harder, although I find it easier to do in Dallas and Collin counties verses Denton and Tarrant. Link to comment Share on other sites More sharing options...
chase_stormz Posted November 19, 2011 Share Posted November 19, 2011 new gfs increases the llj a tad more Link to comment Share on other sites More sharing options...
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