General Weather Discussion - April 2014

[Dessert Fox]

Dessert Fox, this is in no way directed at you, more aimed the mainstream weather. When we have a chance of rain, its 40% and 20%. But, when we have a chance of tornadoes, its 4/10 and 2/10???? Most of us can do some basic math.

I agree, I'm glad it's not my system.

[zookeeper]

I agree, I'm glad it's not my system.

Just FYI.....you have an avatar of Erwin Rommel, the "Desert Fox", but your username is "Dessert Fox" like one of these -


Maybe Pete or Martin could change it for you. (If it's not already taken). Easy mistake though.

[venture]

Mmmm cheese cake.

[Dessert Fox]

Just FYI.....you have an avatar of Erwin Rommel, the "Desert Fox", but your username is "Dessert Fox" like one of these -


Maybe Pete or Martin could change it for you. (If it's not already taken). Easy mistake though.

It wasn't a mistake, just a little play on words

[zookeeper]

I figured with Rommel's pic it was a mistake. Sorry! Still, the cheese cake looks good anyway.

[Dessert Fox]

No problem, the mistake was worth looking at the pic haha

[SoonerDave]

Just FYI.....you have an avatar of Erwin Rommel, the "Desert Fox", but your username is "Dessert Fox" like one of these -


Maybe Pete or Martin could change it for you. (If it's not already taken). Easy mistake though.

Now that's a picture worth warning the neighbors about. As in yum. Maybe we could come up with a cool, mathematical-sounding factor for cheesecake pictures, like Caloric Available Potential Eatage...make up maps and outlooks and everything

[bchris02]

Reed Timmer should apologize for saying this is going to be the biggest outbreak since 2011. 2011 was one of the most violent years in recorded history and its looking more and more like this event is going to be much less high-end than originally thought.

[SoonerDave]

Verrry interesting tweet from Gary England:

All Okla Folks: Don't buy the hype about tornadoes, they may or may not happen. By Fri eve we will have a better idea about Sat. Jump Back!

I think there's lots of hedging going into Saturday about what's been predicted about Saturday.

[silvergrove]

I think there's lots of hedging going into Saturday about what's been predicted about Saturday.

¯\_(ツ)_/¯

[SoonerDave]

Venture: Definition clarification time. I keep seeing the phrase "Mid-level speed max is moving...." I'm trying like crazy to figure out what, exactly, the term "speed max" means. Is it an area of temperature or pressure differential that could but hasn't yet formed into a surface low, or just a wind boundary, or ???????

Guess the one I'm trying to interpret is from this paragraph:

STRONG MID-LEVEL SPEED MAX IS FORECAST TO ROUND THE BASE OF A
PROGRESSIVE TROUGH ALONG THE SWRN U.S./MEXICAN BORDER EARLY SATURDAY
BEFORE SHIFTING INTO NM BY 27/00Z.

[PennyQuilts]

Reed Timmer should apologize for saying this is going to be the biggest outbreak since 2011. 2011 was one of the most violent years in recorded history and its looking more and more like this event is going to be much less high-end than originally thought.

He really jumped the gun - only goes to show that most of the time, you need to wait until much closer to go time to do more than offer possibilities filled with caveats.

[PennyQuilts]

Even Mike Morgan is downplaying it, now.

[soonerguru]

He really jumped the gun - only goes to show that most of the time, you need to wait until much closer to go time to do more than offer possibilities filled with caveats.

He seems like a douche. I was appalled when otherwise smart friends of mine were sharing his histrionic garbage post on Facebook. From this point forward, when I hear his name, I will tune him out.

[venture]

NAM and GFS are in pretty decent agreement tonight on coverage. Essentially very limited coverage until evening. Then a few isolated storms before a line storms form up - kinda similar to yesterday in my opinion. The difference here are the mechanics will be in place for some stronger storms than what we had last night.

One thing I always try to drive home. Risk level does not equal severity level all the time. I fully expect everything to stay a Slight Risk for Saturday but that doesn't mean there won't be a few tornadoes or some extremely large hail. It just means there won't be several reports of either. This is why I can't stand local media doing their own outlooks and changing definitions. Even just one tornado can make it a bad day for someone, so while outbreaks are more "sexy" for people to drum up...some tend to lose focus on the importance of following even the slightest chance.

[ou48A]

Venture: Definition clarification time. I keep seeing the phrase "Mid-level speed max is moving...." I'm trying like crazy to figure out what, exactly, the term "speed max" means. Is it an area of temperature or pressure differential that could but hasn't yet formed into a surface low, or just a wind boundary, or ???????

Guess the one I'm trying to interpret is from this paragraph:







Quote Originally Posted by The NWS Weather Epistle

STRONG MID-LEVEL SPEED MAX IS FORECAST TO ROUND THE BASE OF A
PROGRESSIVE TROUGH ALONG THE SWRN U.S./MEXICAN BORDER EARLY SATURDAY
BEFORE SHIFTING INTO NM BY 27/00Z.

Let me take a stab at this and if I'm wrong I hope somebody corrects me....Please.

A speed max would be the jet stream winds that occur when they rotate around an upper level low... (jet maximum)
It's strength is important to know because it helps evacuate air from the top of thunder storms and has a a siphoning effect. This acts as a lifting mechanism for air at lower levels that's often warm and moist.
It aids the formation of tornadoes hail and high winds.

[LocoAko]

He seems like a douche. I was appalled when otherwise smart friends of mine were sharing his histrionic garbage post on Facebook. From this point forward, when I hear his name, I will tune him out.

That, and that MSNBC article were absolutely atrocious. It's like they purposely removed the word "possible" in all of the forecasts and ran with it. Completely and utterly irresponsible. And you know who gets the blame when the "forecast" "busts"? Us, the meteorologists. It's crap.

Also, while I am not condoning Reed's claim about the outbreak, it is entirely possible that Monday and Tuesday could be largescale outbreaks in the Southeast. So while he did include is in that comment erroneously, IMO), it could still be quite bad elsewhere potentially.

[venture]

A lot of graphics ahead! You are warned.

While we wait for the Euro to come out here in the next hour or two...he is a look at the various models for 7PM Saturday.

00Z GFS

7PM Saturday	10PM Saturday	1AM Sunday	4AM Sunday

00Z NAM

7PM Saturday	10PM Saturday	1AM Sunday	4AM Sunday

00Z UKMET

7PM Saturday	7AM Sunday

00Z Regional GEM - Canadian Model

[venture]

Okay so the take away to the models in the images above. We have 3 out of those 4 presented that are breaking out precip along the dryline in the early evening hours and continuing it over night - even increasing coverage overnight. Now in this post I wanted to review the SREF run from SPC which is an ensemble forecast. OU48 referred to this earlier.

First tomorrow. Something I found interesting was that the SREF members have storms developing along the dryline tomorrow out west. I still don't think this is likely, but the risk is there.



Supercell Parameters for Friday - not really high, but conditions are there.



Saturday Max Total Precip by 7PM - 3 Hr Total



Supercell Parameter



Sig Tornado Parameter

[venture]

The new Day 2 for Saturday...


DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1233 AM CDT FRI APR 25 2014

VALID 261200Z - 271200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MID-MO VALLEY TO THE
SRN PLAINS...

...SUMMARY...
ISOLATED TO PERHAPS SCATTERED SEVERE THUNDERSTORMS ARE ANTICIPATED
FROM THE MID-MISSOURI VALLEY TO THE SOUTHERN GREAT PLAINS ON
SATURDAY EVENING INTO EARLY SUNDAY. LARGE HAIL IS EXPECTED TO BE THE
PRIMARY HAZARD.

...SYNOPSIS...
A BROAD UPPER-LEVEL TROUGH OFF THE PACIFIC COAST WILL SHIFT INLAND
BY EARLY SAT. A VIGOROUS SHORTWAVE IMPULSE WILL PROGRESS FROM SRN CA
TO THE LEE OF THE SRN ROCKIES WITH A COMPACT SPEED MAX ACROSS THE
DESERT SW EJECTING ONTO THE CNTRL/SRN HIGH PLAINS EARLY SUN. THESE
FEATURES WILL INDUCE LEE CYCLOGENESIS OVER ERN CO WITH A WARM FRONT
ARCING EWD NEAR THE MO VALLEY. THE DRYLINE SHOULD MIX EWD INTO CNTRL
KS AND ACROSS W TX...BEFORE RETREATING WWD DURING THE EVENING. A
PACIFIC COLD FRONT WILL SWEEP EWD AND EVENTUALLY OVERTAKE THE
DRYLINE IN THE SRN HIGH PLAINS EARLY SUN.

...CNTRL/SRN PLAINS...
IN THE WAKE OF A RECENT COLD FRONT INTRUSION TO NEAR THE TX GULF
COASTAL PLAIN...MODIFIED GULF MOISTURE SHOULD BE CONFINED TO TX AT
12Z/SAT. ROBUST LOW-LEVEL MOISTURE ADVECTION IS EXPECTED THROUGH THE
DAY AS FLOW STRENGTHENS BENEATH A STOUT EML. THIS SHOULD YIELD A
BROADENING PLUME OF MIDDLE 50S TO MIDDLE 60S SURFACE DEW POINTS FROM
PARTS OF THE MID/LOWER MO VALLEY SWD TO THE WRN GULF COAST BY SAT
EVENING.

INTENSE SURFACE HEATING WILL OCCUR ALONG/W OF THE DRYLINE WITH UPPER
80S TO MIDDLE 90S TEMPERATURES FROM CNTRL KS TO W TX. AS WEAK
MID-LEVEL HEIGHT FALLS OVERSPREAD THE DRYLINE NEAR 00Z...LOW-LEVEL
CONVERGENCE WILL STRENGTHEN AND SHOULD RESULT IN A FEW DISCRETE
STORMS. THIS ACTIVITY SHOULD INITIALLY BE HIGH-BASED WITH SURFACE
DEW POINT DEPRESSIONS AOA 30 DEG F. VERY STEEP TROPOSPHERIC LAPSE
RATES ALONG WITH A MODERATE COMBINATION OF BUOYANCY/DEEP-LAYER SHEAR
SHOULD SUPPORT SUPERCELLS PRIMARILY PRODUCING LARGE HAIL /SOME
SIGNIFICANT/ AND LOCALLY SEVERE WINDS.

STRONG WARM SECTOR INHIBITION DOES RENDER SUBSTANTIAL UNCERTAINTY IN
OVERALL STORM COVERAGE/SUSTAINABILITY AND TORNADO POTENTIAL DURING
THE EVENING. GUIDANCE VARIES SUBSTANTIALLY WITH THE DEGREE OF
CONVECTIVE SIGNAL FROM THE MINIMALIST NAM/UKMET TO WIDESPREAD GFS.
GIVEN A RETREATING DRYLINE SCENARIO AND LARGER MID-LEVEL HEIGHT
FALLS HOLDING OFF UNTIL OVERNIGHT...CONFIDENCE IS LOW IN HOW
CONVECTION MAY ULTIMATELY EVOLVE. BUT WITH A LLJ STRENGTHENING TO
AOA 50 KT ALONG WITH AN INFLUX OF RICHER MOISTURE...ANY SUSTAINED
DIURNALLY-DRIVEN STORMS MAY PRODUCE A TORNADO BEFORE THE BOUNDARY
LAYER DECOUPLES.

AS LARGE-SCALE ASCENT STRENGTHENS SUBSTANTIALLY EARLY SUN...ELEVATED
TSTMS WILL INCREASE IN COVERAGE FROM THE MID-MO VALLEY TO THE SUN
PLAINS WITH STEEP LAPSE RATES SUPPORTING A LARGE HAIL THREAT. SOME
OF THIS ACTIVITY MAY BECOME SURFACE-BASED ACROSS THE SRN
PLAINS...WHERE SURFACE DEW POINTS INCREASE INTO THE MIDDLE
60S...SUPPORTING POTENTIAL FOR ALL SEVERE HAZARDS.

..GRAMS.. 04/25/2014

[venture]

I added some emphasis and it appears SPC is starting to hint at what some of us starting to pick up on. It doesn't happen often, but we might be looking at a nighttime event. Not locked in at all. A lot of things still have to come together. Moisture needs to be rich and get in place. Initiation has to be well underway before the dryline retreats and storms established. Among other things. Depending on which model solution works out, storm coverage - as mentioned earlier - could increase as the night goes on which means the risk will remain. This possibly won't be a situation where the threat ends shortly after the sun goes down. Get the coffee ready...

[venture]

00Z Euro keep things pretty much the same. It lights up the dryline by 7PM throughout western OK. Through 1AM it has two areas of precip - one north and one south...not that this should be taken literally right now. Then by 7AM reignites precip over a large area of OK west of I-35. It is also SLIGHTLY slower with dryline progression keep it to right on I-35 by 1PM. This matches what it did on the 00Z run last night.

[venture]

Sunday Day 3 has a slight risk just east of I-35 and a Moderate Risk for extreme SE OK. This could be the first shot a High Risk for this year...especially with a Day 3 Moderate.



DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0229 AM CDT FRI APR 25 2014

VALID 271200Z - 281200Z

...THERE IS A MDT RISK OF SVR TSTMS FOR THE ARKLATEX AREA...

...THERE IS A SLGT RISK OF SVR TSTMS FROM THE MO VALLEY TO THE WRN
GULF COAST...

...SUMMARY...
OUTBREAK OF SEVERE STORMS POSSIBLE ON SUNDAY ACROSS PARTS OF THE
CENTRAL STATES WITH LARGE HAIL...DAMAGING WINDS...AND TORNADOES.

...SYNOPSIS...
A VIGOROUS SHORTWAVE TROUGH EXPECTED TO BE CENTERED IN THE LEE OF
THE SRN ROCKIES AT 12Z/SUN WILL SUBSTANTIALLY SLOW AS IT PROGRESSES
TOWARDS NEB. AN ATTENDANT MID-LEVEL JET /AOA 50 KT AT 500 MB/ WILL
PERSIST FROM THE DESERT SW...CURLING NWD FROM THE RED RIVER TO THE
MO VALLEY. AT THE SURFACE...A CYCLONE SHOULD DRIFT EWD OVER THE
CNTRL PLAINS WITH A WARM FRONT ARCING EWD ACROSS THE CORN BELT TO
THE LOWER OH VALLEY. A DRYLINE/WEAKENING PACIFIC COLD FRONT SHOULD
REACH ERN KS/OK INTO DEEP S TX IN THE LATE AFTERNOON.

...MO VALLEY TO THE WRN GULF COAST...
THE WARM SECTOR WILL BECOME INCREASINGLY BROAD/MOIST BENEATH AN EML
WITH LOWER 60S SURFACE DEW POINTS BECOMING ESTABLISHED NEAR THE WARM
FRONT AND MIDDLE TO UPPER 60S INTO THE LOWER/MID-MS VALLEYS AND
ARKLATEX BY SUN AFTERNOON. INITIALLY STEEP MID-LEVEL LAPSE RATES
ALONG WITH MODERATE TO STRONG DEEP-LAYER SHEAR WILL SUPPORT AN
EXPANSIVE AREA OF ORGANIZED SEVERE POTENTIAL.

AREAS OF CONVECTION SHOULD BE ONGOING AT 12Z/SUN ACROSS PARTS OF THE
SRN PLAINS TO MID-MO VALLEY. SOME OF THIS ACTIVITY MAY ALREADY BE
SURFACE-BASED OR WILL TRANSITION TO BECOMING SO AS DIURNAL HEATING
ENSUES. CLUSTERS OF ISOLATED TO SCATTERED SEVERE STORMS WILL BE
POSSIBLE AS CONVECTION LIKELY DEVELOPS N/E.

THE MOST PROBABLE SEVERE RISK SHOULD DEVELOP ALONG AND AHEAD OF THE
DRYLINE TOWARDS PEAK HEATING...WITH CONFIDENCE GREATEST IN THIS
OCCURRING NEAR THE SRN PERIPHERY OF EARLY DAY STORMS /CENTERED OVER
THE ARKLATEX/. WITH ROBUST HEATING OCCURRING ACROSS TX...MLCAPE
SHOULD PUSH 2500 J/KG AHEAD OF THE DRYLINE. HODOGRAPHS APPEAR QUITE
CONDUCIVE TO SUPERCELLS...CAPABLE OF PRODUCING VERY LARGE HAIL AND
STRONG TORNADOES. WITH THE DRYLINE STALLING ACROSS NERN TX SUN
EVENING...TRAINING SUPERCELL CLUSTERS MAY CONTINUE INTO THE NIGHT.

ALONG THE DRYLINE FARTHER N INTO THE MO VALLEY...EARLY DAY
CONVECTION MAY TEND TO LIMIT A GREATER SEVERE RISK. BUT WITH STRONG
INSOLATION...MODERATE BUOYANCY MAY DEVELOP WITHIN A STEEP LAPSE RATE
ENVIRONMENT. ALTHOUGH DEEP-LAYER WIND PROFILES SHOULD BE LARGELY
MERIDIONAL...SUFFICIENT CURVATURE TO THE LOW-LEVEL HODOGRAPH WOULD
SUPPORT UPDRAFT ROTATION...WITH ALL SEVERE HAZARDS POSSIBLE.

..GRAMS.. 04/25/2014

[OkieHornet]

looks like a rain slicker is in order for the norman music festival tomorrow night! and maybe a hard hat, too...

[ou48A]

looks like a rain slicker is in order for the norman music festival tomorrow night! and maybe a hard hat, too...

And a maybe know where a nocturnal tornado shelter is in down town Norman.

If you are in Norman do not depend on the city of Norman warnings.
Their track record of timely warnings is not great.
I have seen far better set ups and far more timely city tornado warnings issued in small towns who do not have nearly as many resources as the city of Norman.