THURSDAY FIRST CHASE?

Tim Marshall

ATTENTION CHASERS: An active weather pattern lies ahead. A powerful storm system is progged to romp through the plains Thursday evening and may present the first chase opportunity of the new year. As typical with early spring situations, low level moisture and cloud cover will be factors to watch. The latest run of the GFS has a jet max going through Oklahoma, so I would look at the area from OKC north to ICT for Thursday evening. Then, we get FROPAD and what moisture there is -gets pushed back into the Gulf until perhaps Sunday night or Monday night. It is time to buy film and get those batteries charged! TM
 
Thursday

The upper air dinamics look good. Even the GFS forecasted Hodograph looks good. The only prob I see is the lack of low-level moisture. GFS and ETA only forecasting ranges Td’s in the mid 40’s in OKC. The Gulf is being stingy with the moisture.

Time will tell though. I would settle for a clash of thunder. It’s been several months sense I’ve even heard that.

Mickey Ptak
 
Gosh I cannot believe the prospect of chasing has already begun!!! Does this give you experts any clues as to the up and coming season??
 
Looks like California may see the action first!!

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0257 AM CST MON FEB 16 2004

VALID 181200Z - 191200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
SRN STREAM UPPER TROUGH EXPECTED TO EVOLVE OVER THE E PACIFIC DURING
THE NEXT 48 HOURS SHOULD REACH THE CNTRL CA CST BY 12Z WEDNESDAY.
THE SYSTEM SHOULD CONTINUE E/SE ACROSS SRN CA/NV...AND REACH THE
FOUR CORNERS REGION BY 12Z THURSDAY. IN THE PROCESS...PACIFIC
SURFACE LOW ASSOCIATED WITH THE TROUGH SHOULD WEAKEN OFF THE NRN CA
CST DURING THE DAY ON WEDNESDAY...AND REFORM OVER THE SRN GRT BASIN
LATER WEDNESDAY/EARLY THURSDAY.

...CNTRL/SRN CA...
FRONTAL BAND ASSOCIATED WITH PACIFIC TROUGH SHOULD MOVE E/SE ACROSS
CNTRL AND SRN CA DURING THE FIRST HALF OF THE PERIOD...ACCOMPANIED
BY SHOWERS AND POSSIBLY EMBEDDED THUNDER. WHILE 40+ KT DEEP SHEAR
WILL BE SUFFICIENT FOR SUPERCELLS...THE SHEAR SHOULD WEAKEN AND BACK
IN DIRECTION WITH TIME AS UPPER LOW MOVES ESEWD. THIS WILL LIKELY
FAVOR A LINEAR MODE WITH ANY SUSTAINED CONVECTION IN THE FRONTAL
BAND...AND SHOULD ALSO LIMIT THE SEVERE THREAT GIVEN WEAK
SURFACE-BASED INSTABILITY /SBCAPE AOB 100 J/KG/.

IN WAKE OF FRONTAL BAND...SCATTERED LINES OF LOW-TOPPED CONVECTION/
THUNDER EXPECTED TO PRECEDE/ACCOMPANY MAIN UPPER VORT IN AREA OF
LINGERING LOW LEVEL CONVERGENCE OVER CNTRL CA. COMBINATION OF
CYCLONIC ONSHORE FLOW AND MODEST SURFACE HEATING/LOW LEVEL SPEED AND
DIRECTIONAL SHEAR MAY PROVE SUFFICIENT FOR A FEW SUSTAINED
STORMS/WEAK SUPERCELLS. THESE MAY YIELD MARGINALLY SEVERE HAIL AND
PERHAPS A BRIEF TORNADO DURING THE AFTERNOON AND EARLY EVENING.


Always like to see that!
 
I've definitely got my eye on Thu/Fri, depending on the timing of the system. As usual, I'm holding off on my serious analysis until the thing is on the doorstep, but I will be glancing at the upper air maps frequently this week in anticipation of what day to tell my boss I ain't gonna be at work :D

The thing I'm watching with the most curiosity are the surface temps. I have a sneaking feeling those 70s will crep surther north than currently progged. But either way, right now I'm assuming the southern end of the action area, simply because I'm following the trail down to the best Tds/DDs.
 
From the Tulsa WFO:
STILL SOMEWHAT OF A QUESTION MARK CONCERNING POPS/TSTM POTENTIAL
ON FRIDAY. GFS STILL FORECASTING RATHER LIMITED LOW LEVEL
MOISTURE AHEAD OF COLD FRONT. IMPRESSIVE DYNAMICS/LIFT HOWEVER
EXPECTED WITH UPPER SYSTEM...AS LEFT FRONT QUAD OF 110 KT UPPER JET
SHIFTS EAST INTO EASTERN OKLAHOMA BY 12Z FRIDAY. DEPENDING ON
MOISTURE AVAILABILITY...THERE IS THE POTENTIAL FOR ELEVATED STORMS
EARLY FRIDAY MORNING AS STRONG LOW LEVEL JET DEVELOPS. THEN
REDEVELOPMENT ALONG THE DRY LINE AND/OR COLD FRONT FRIDAY
AFTERNOON...WITH THE BEST PRECP CHANCES ACROSS NW ARK. VERY STEEP
LAPSE RATES COUPLED WITH STRONG DEEP LAYER SHEAR SUGGEST ANY
CONVECTION THAT DEVELOPS WOULD LIKELY POSE A SEVERE THREAT WITH
DAMAGING WINDS/VERY LARGE HAIL. STAY TUNED.


After looking at some model data, I think that, while this is perhaps the first of this type of spring-like system to come through this year, I think we may still need another few weeks for the gulf to start to juice up there air down there. In this particular case, the upper dynamics look quite interesting, but the gulf just doesn't look like it's going to cooperate. I mean, while there is fetch from the gulf, there is a continental trajectory to the air over the eastern gulf. In fact, there are northeasterly winds all the way well east of Cuba, which means that this "Gulf" air is just modified continental air from the SE US (courtesy of the High off the FL panhandle).
At any rate, the sfc system looks quite nice. However, with ETA progged Tds only in the 40's, I think this may not be the first system we are all looking for. Definately something to keep our eyes on, however! With the increasing sun angle and related increase in Gulf water temps / evaporation, spring is right around the corner! :)

Jeff Snyder
KC0HJX
Http://www.TornadoCentral.com
 
Looks like California may see the action first!!
Click to expand...

If I was on the West Coast and couldn't make it out to the Plains for Thurs/Fri, I'd definitely have my eyes on the San Joaquin Valley for Wed afternoon. Right now the GFS and ETA both suggest the upper level low won't close off, will move onshore btwn Monterey and San Luis Obispo during the time of peak heating, and the SJV will be under the left front quad of a jet max. If this happens, then anywhere along the Hwy 99 corridor between about Merced and Tulare could be a good place to be on Wed afternoon. But if the low ends up closing off and digging further south (which often happens) then the southern CA coast might see some interesting wx come Wed. Either way I wouldn't be surprised to hear at least one hail and/or funnel cloud report that way a couple days from now.
 
While the shortwave that will move into the southern plains on Thursday does show great shear, it is very unlikely that the low level moisture will be in place. The Gulf doesn't have time to recover from the current pounding it's taking. I'm actually looking forward to a warm, windy, sunny day!

The ETA is forecasting very warm 850 mb temps (~17C). Mix that down dry adiabatically...low 80's aren't out of the question in southwest OK Thursday. And if the dryline mixes east quickly enough causing excellent downsloping, extreme western OK could reach the upper 80's. This is all assuming no cirrus deck. Based on all of this, I think on Thursday several high temperature records could be broken *IF* the current ETA forecast verifes.

Looking at what the GFS is showing, the southern Texas could start seeing severe weather over the next couple weeks. It shows the southern branch of the jet digging into the southwest U.S. and northern Mexico.

Spring really is just around the corner...

Jim Bishop
 
Personally I'm not impressed, and I haven't even looked at any data (fantasy-progs) recently. From what I hear through the grapevine, it will be your traditonal, moisture-deprived late winter event (note I said late winter - not early sping! :lol: )

It does give those of us with rife SDS some hope, though.......hope that the Gulf and Spring have not abandoned us for 2004......surprise, surprise.

I'll sit here in OUN and keep my butt workin'.....conserve my reserves for sometime like May/June.

K.
 
Personally, I just look at this as a sign of things to come :) Being February, and we are just even *considering* the possibility of chasing is a good sign. Last year we had a great day in March 17.... hopefully we can get a good setup like that this year early on. I wouldn't mind chasing during spring break.

Aaron
 
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DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0231 AM CST TUE FEB 17 2004

VALID 181200Z - 191200Z

THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM 15 SSE
MRY 25 SW SCK 50 ENE SCK 10 NNE NID PMD 10 SE VBG.

GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 30 SSW EKA 40 SSE MHS
35 W LOL 25 E EKO 25 ESE MLD 25 SSW RKS 35 W ASE 35 NNW 4SL 50 ENE
SOW 50 WNW PHX 15 SSW YUM.

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF CNTRL AND SRN
CA...

...SYNOPSIS...
ENERGETIC SRN STREAM JET WILL BE MAIN FEATURE AFFECTING SENSIBLE
WEATHER ACROSS THE LOWER 48 THIS PERIOD. TROUGH ALREADY DEVELOPED
WITHIN THIS BAND OF FLOW...WITH MAIN AXIS ATTM AROUND 135W... SHOULD
FURTHER AMPLIFY AS UPSTREAM RIDGE BUILDS ALONG 150W DURING THE NEXT
24-36 HRS. THE TROUGH WILL LIKELY TRACK E/SE ACROSS CNTRL/SRN CA ON
WEDNESDAY...AND SHOULD REACH CNTRL AZ BY 12Z THURSDAY.

AT LOWER LEVELS...MAIN FRONTAL BAND PRECEDING UPPER TROUGH SHOULD
MOVE E ACROSS THE SRN HALF OF CA WEDNESDAY AFTERNOON AND EVENING...
WHILE MAJOR PORTION OF ASSOCIATED SURFACE LOW REDEVELOPS E OF THE
SIERRA. AN AREA OF WEAK LOW PRESSURE WILL PROBABLY LINGER OVER NRN
PORTIONS OF THE CNTRL VLY UNTIL UPPER TROUGH AXIS PASSES E INTO
NV/AZ WEDNESDAY NIGHT.

...CNTRL/SRN CA...
FRONTAL BAND OF SHOWERS AND WIDELY SCATTERED EMBEDDED THUNDERSTORMS
WILL MOVE ACROSS THE SRN HALF OF CA DURING THE FIRST HALF OF THE
FORECAST PERIOD. WHILE AMPLE /40-50 KT/ DEEP SHEAR WILL EXIST TO
SUPPORT SUPERCELLS...SHEAR VECTORS SHOULD BACK AND DIMINISH WITH
TIME. COUPLED WITH FORCED ASCENT ALONG FRONT...MAIN CONVECTIVE MODE
SHOULD BE LINEAR. GIVEN WEAK LAPSE RATES AND WIDESPREAD CLOUDS...
ANY SEVERE THREAT /BRIEF TORNADOES/ SHOULD REMAIN LIMITED.

A SOMEWHAT GREATER THREAT FOR ISOLATED SEVERE MAY DEVELOP WEDNESDAY
AFTERNOON IN POST FRONTAL ENVIRONMENT FARTHER N ACROSS THE CNTRL
VLY. MODEST SURFACE HEATING BENEATH MID LEVEL COLD POCKET
ACCOMPANYING MAIN UPPER VORT /500 MB TEMPS AOB MINUS 25C/ SHOULD
BOOST SBCAPE TO AOA 500 J/KG...GIVEN SURFACE DEWPOINTS IN THE LOW
50S AND TEMPERATURES IN THE LOW 60S. COUPLED WITH WEAK LOW LEVEL
CONVERGENCE AND SLIGHTLY BACKED LOW LEVEL FLOW ASSOCIATED WITH
LINGERING LOW PRESSURE TO THE N...SETUP MAY PROVE SUPPORTIVE OF A
FEW LOW-TOPPED SUPERCELLS/MULTICELL CLUSTERS WITH MARGINALLY SEVERE
HAIL/BRIEF TORNADOES. ANY SUCH THREAT SHOULD DIMINISH AFTER DARK.

..CORFIDI.. 02/17/2004
 
Just looked at the Tuesday morning progs (ETA and GFS) for Thursday. I like this compact progressive low that will be moving due east. Unfortunately, there will be no significant low-level moisture. Both progs are showing low to mid-50's dewpoints for the Dallas area. Lots of high based junkus, I'm afraid. Then what little surface moisture there will be -gets wiped out for a few days. The next chance for severe looks like Tuesday evening in northern Louisiana. Looks like I'll have to wait until March for my first chase. TM
 
yes daft question Karen I know. :D
Click to expand...

Nah, not really - and even if it was I'd understand. Coming from the UK, I've asked my fair share of stupid questions, too! :lol:

(OK OK I didn't mean that to sound the way it did. I meant coming from the UK and not KNOWING anything about storms over here....)

Ask away......."let thought be contact"......

Sorry.....breaking into "YES", there......

Karen

..
 
The thing I HATE about this late-winter / early-spring time is that we often get these continental air intrusions DEEP into the GoM (actually, completely through the GoM sometimes). Looking at tonights GFS, it seems that while the southern-stream jet will remain active (with numerous closed 500mb lows coming through atleast TX in the next 10 days), each system is followed by a high that flushes deep into the Gulf. This means that even 2 or possibly 3 days of return flow does very little to get even modest low-level moisture into the southern plains. Ugh...

Jeff
 
In response to Jeff Snyder's post: Yes, the depth of surface moisture is always a problem in the early spring. Even with south winds off the Gulf for two or three days, we struggle to get into the 50's dewpoints here in TX. Looking ahead, the progs have a closed low stuck off the California coast with wave after wave romping over the state next week. Unfortunately, surface moisture conditions remain dismal. TM
 
Hello

I'm waiting until mid March to start chasing, got some AWSOME footage last March on the 17th!!
 
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