January Weather Discussion: Slight Chance Severe Storms

[biggerbyte]

I REALLY have to take the dreaded whatever attitude today with this. I allowed myself to get all worked up over long range models, which I don't ever, ever do. It sounded nice and exciting, and God knows we all need a little winter fun around here.
Oh well!!! It is back to ignoring the models and getting down to what is really going on. The weekend will be the right time to look at this event.

[biggerbyte]

Oh, and newbies, don't give up just yet. This is just another one of those situations where it is too early to give a real forecast, and the models are clueless. If we get this massive pool of very cold air, it will dive south. We have to get to the weekend before we can answer the if, when, how long, etc. It's not over yet. I would, however, advise against believing anything, one way or the other, until then. We may just be seeing model flip flopping this morning, with nothing in reality actually changing from last night.
We'll look at it later today.

[biggerbyte]

Lol

This is a good one.

The NWS forecast last night for early next week in my area was 30s for highs, and 20s for lows. This morning it is:

Monday Night and Tuesday
Partly cloudy. Lows in the lower 30s. Highs in the lower 50s.

If this is accurate, folks, then we have a case of same old, same old. I'll look at it later, as they may have simply slowed the push of cold air down a bit.

[wxman57]

So is this backing off just the models flip flopping again, or is this a definite trend now?

I'll let you know if it's a trend in 2-3 days. For now, it's just a model run.

Just looking at obs in NW Canada/NE Alaska, still no cold air there and pressures are below 1000mb in many areas. No massive high pressure area yet. We just have to wait 2-3 days to see what DOES build in NW Canada.

[perk]

So is this backing off just the models flip flopping again, or is this a definite trend now?

I'll let you know if it's a trend in 2-3 days. For now, it's just a model run.

Just looking at obs in NW Canada/NE Alaska, still no cold air there and pressures are below 1000mb in many areas. No massive high pressure area yet. We just have to wait 2-3 days to see what DOES build in NW Canada.

I'm gonna take Wxman57's advice and avoid further disappointment.

[srainhoutx]

HPC seems to think it's just a blip with their Morning Update Headline...

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
756 AM EST WED JAN 05 2011

VALID 12Z SUN JAN 09 2011 - 12Z WED JAN 12 2011

...A COLD PATTERN FOR THE NATION WITH STORM POTENITAL OVER THE US
SRN TIER AND UP THE EAST COAST...

STILL EXPECT MOST OF THE CONUS TO REMAIN UNDER BELOW NORMAL
HEIGHTS ALOFT FOR MOST OF THE MEDIUM RANGE PERIOD...CORRESPONDING
TO RIDGING/ABOVE NORMAL HEIGHTS AT HIGHER LATITUDE. GUIDANCE IS
SHOWING SOME SHIFTING IN EMPHASIS WITH THE HIGH LATITUDE
RIDGING...WITH A WEAKENING TREND OVER CANADA AND A STRENGTHENING
TREND OVER/NEAR ALASKA. THIS TRANSITION SHOULD EVENTUALLY LEAD TO
SOMEWHAT MORE PACIFIC FLOW REACHING THE WRN CONUS. LATEST AND
RECENT MODEL/ENSEMBLE GUIDANCE SHOWS GOOD AGREEMENT WITH THE LARGE
SCALE SCENARIO THRU THE PERIOD. HOWEVER THERE ARE PERSISTENT
DETAIL DIFFERENCES AND RUN TO RUN CONTINUITY CHANGES WITH THE
AMPLITUDE/TIMING OF DAY 3 SAT NWRN CONUS/SWRN CANADA ENERGY
AMPLIFYING INTO THE WEST/PLAINS SUN/MON...WHICH IN TURN AFFECT A
TROF/CLOSED LOW ENTERING THE SWRN CONUS/NWRN MEXICO UNDERNEATH
FRI/SAT LEADING INTO THE MEDIUM RANGE.

AFTER GUIDANCE GENERALLY TRENDED FASTER/MORE AMPLIFIED WITH
W-CENTRAL CONUS FLOW IN THE PRIOR 24 HOURS...SOLUTIONS NOW REFLECT
SOME MODERATION AWAY FROM THAT IDEA AND AS A RESULT THE LEADING
SRN STREAM SHORTWAVE IS MORE SUPPRESSED AS REFLECTED IN MOST
GUIDANCE FROM BEFORE YESTERDAY. THE 00Z GFS/CMC ARE THE LEAST
AMPLIFIED BY EARLY NEXT WEEK...BUT THE CMC HAS AN OUTLIER
EVOLUTION OVER THE ERN PAC WHICH ARGUES FOR DISCOUNTING ITS
SOLUTION. GIVEN THE DEVELOPMENT OF DAILY OSCILLATION IN
GUIDANCE...AN INTERMEDIATE SOLUTION COMPOSED OF THE 00Z ECMWF AND
12Z ECMWF ENSEMBLE MEAN APPEARS TO BE THE BEST OPTION THRU AT
LEAST THE WEEKEND. LATER IN THE PERIOD THE 00Z GEFS MEAN JOINED
THE ECMWF MEAN ALOFT AND IN SHOWING ORGANIZED WRN ATLANTIC SURFACE
CYCLOGENSIS CLOSER TO THE COAST THAN THE 00Z GFS/ECMWF. TYPICAL
DIFFICULTY THAT GUIDANCE HAS WITH IMPORTANT DETAILS BEYOND 2-3
DAYS WOULD RECOMMEND A COMPROMISE BETWEEN THESE TWO CLUSTERS AS A
STARTING POINT...BUT THE UPDATED HPC PROGS DID ADJUST THE LOW
SLIGHTLY BACK TOWARD THE COAST CONSIDERING TRENDS FROM THE 06Z
GFS/DGEX AND THE 06Z GEFS MEAN AS PER POTENTIAL MID-UPPER LEVEL
DYNAMIC SUPPORT ALOFT. HOWEVER...THE 06Z GEFS/YESTERDAYS 12Z
ECMWF ENSEMBLE MEANS THAT WERE USED WITH THE 00Z ECMWF TO DERIVE
THE HPC BLENDED SOLUTION FOLLOW THIS TREND BETTER THAN THE 00Z
GEFS/ECMWF ENSEMBLE MEANS...LEAVING LINGERING UNCERTAINTY FOR WHAT
COULD BE A ANOTHER SIGNIFICANT WINTER COASTAL STORM.

AS FOR OTHER FEATURES...THERE IS GRADUAL IMPROVEMENT IN AGREEMENT
WITH EVOLUTION OVER THE NE CONUS INTO THE ATLANTIC DURING THE
WEEKEND. THE 00Z GFS IS A LITTLE STRONGER/SHARPER THAN CONSENSUS
WITH ITS SURFACE TROF OVER THE NORTHEAST AS OF EARLY DAY 3 SAT.
THE INITIAL 00Z ECMWF/12Z ECMWF MEAN BLEND ACCOUNTS WELL FOR THE
NON-00Z GFS PREFERENCE HERE. MEANWHILE ALONG THE WEST COAST THE
CANADIAN IS AN OUTLIER WITH ITS DEEP SYSTEM NEARING THE PAC NW
COAST BY EARLY DAY 7 WED. ASIDE FROM TYPICAL TIMING DIFFERENCES
THERE IS DECENT AGREEMENT IN PRINCIPLE ON A MERE WARM FRONT
NEARING THE WEST COAST LATE IN THE FCST. A COMPROMISE AMONG THE
ENSEMBLE MEANS AND SLOWER ECMWF PROVIDES TIMING NEAR THE MIDDLE OF
THE FULL ENVELOPE OF MODEL AND ENSEMBLE SOLUTIONS.

RAUSCH/SCHICHTEL

[ticka1]

Don't the models always have a tendancy to at one point lose the systems. I have seen this happen so many times. I think its time right now to focus on seeing where the actual weather is and how its progressing in real life instead of on the models. Like I have been saying all week - this weekend we will get a more accurate forecast for next week. Long range models in my opinion are just teasers to give you possible scenarios of upcoming weather.

Let's see what today's model runs spit out. LOL

[wxman57]

Don't the models always have a tendancy to at one point lose the systems. I have seen this happen so many times. I think its time right now to focus on seeing where the actual weather is and how its progressing in real life instead of on the models. Like I have been saying all week - this weekend we will get a more accurate forecast for next week. Long range models in my opinion are just teasers to give you possible scenarios of upcoming weather.

Let's see what today's model runs spit out. LOL

Yep, it's quite common for models to lose the cold air in the 5-8 day out time frame. What does concern me (if I'm looking for cold air here) is that there is still no sign of high pressure or cold air in northern Canada. It's forecast to build there in the next 2-3 days. We just have to wait and see if THAT forecast verifies first before we can make any conclusions about our weather next week.

[srainhoutx]

I just spent some time reading the AFD's from MT, ND and WA. There is little doubt from my readings that those areas are certainly expecting possibly the coldest air of this winter to head in this weekend and build with reinforcing shots throughout next week. I told CC on Monday that I would not be surprised to see the models drop the cold air in a couple of days.

[ticka1]

Don't the models always have a tendancy to at one point lose the systems. I have seen this happen so many times. I think its time right now to focus on seeing where the actual weather is and how its progressing in real life instead of on the models. Like I have been saying all week - this weekend we will get a more accurate forecast for next week. Long range models in my opinion are just teasers to give you possible scenarios of upcoming weather.

Let's see what today's model runs spit out. LOL

Yep, it's quite common for models to lose the cold air in the 5-8 day out time frame. What does concern me (if I'm looking for cold air here) is that there is still no sign of high pressure or cold air in northern Canada. It's forecast to build there in the next 2-3 days. We just have to wait and see if THAT forecast verifies first before we can make any conclusions about our weather next week.

Thanks for the reply wxman57 - your point is well said - we should start being able to see this weather happening now -- where-ever that might be -- if its going to happen. Observations and monitoring of cold air will show us if this weather feature develops and how intense or non-intense it will be for us here in SE Texas. Then once that happens the models will be able to forecast is more accurately.

[tireman4]

Patience, I suppose, is the keyword for the next few days.....

[brazoria121]

its going to be a rough 2-3 days lol everyone is going to be kep checking NW AK and IF that high dosent build in theres going to be alot of dissapointed folks

[srainhoutx]

Folks, keep an eye out W as well. While we wait for the strong High Pressure to develop up in AK, the W Coast Upper Air Disturbance is one of the main mechanisms to drive all the cold air expected, well S. The fact that models struggle with those short waves (as the HPC has been noting) and how fast or how slowly (and how strong, for that matter) that disturbance moves across the CA Coast and on E bound will determine our sensible weather here this weekend and beyond. We’ve been down this road before this La Nina season and I expect we'll do it again before we transition into spring.



Oh, and here is what HPC Forecaster, Paul Kocin had to say yesterday regarding that big old AK High Pressure Cell expected...

ALASKA EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
156 PM EST TUE JAN 04 2011

VALID 12Z SAT JAN 08 2011 - 12Z WED JAN 12 2011

THE MEDIUM RANGE IS DOMINATED BY THE DEVELOPMENT OF A VERY
IMPRESSIVE UPPER RIDGE AND CLOSED HIGH AT 500 MB...AS WELL AS THE
DEVELOPMENT OF AN INTENSE SURFACE HIGH. THIS DEVELOPMENT IS
ESPECIALLY PRONOUNCED ON DAYS 5 AND 6/SUNDAY AND MONDAY AND IT
APPEARS THAT THE MODELS HAVE TRENDED WESTWARD OVER THE PAST 24
HOURS.

THERE ARE AREAS OF SIGNIFICANT DIFFERENCES NOT NECESSARILY WITH
THE EVOLUTION OF THE UPPER RIDGE BUT MORE WITH THE MOVEMENT OF AN
UPPER LOW MOVING SOUTHWARD ALONG THE EASTERN PERIPHERY OF THE
BUILDING RIDGE. MOST OF THE OPERATIONAL RUNS...ESPECIALLY THE
EUROPEAN/UKMET AND CANADIAN KEEP THIS SYSTEM ON THE EAST
SIDE...BUT THE GFS HAS BEEN CONSISTENT WITH HAVING IT DROP SOUTH
AND THEN WESTWARD ACROSS SOUTHERN ALASKA BY DAYS 6 AND 7/MONDAY
AND TUESDAY.

THE OVERNIGHT AND 12Z GEFS MEAN HAS A STRONGER EASTERLY COMPONENT
THAN THE OTHER MODELS SUGGESTING THAT ANY SHORTWAVE COULD TRAVEL
WEST UNDERNEATH THE CELL. THE 12Z RUNS OF THE UKMET/CANADIAN AND
THE OVERNIGHT CANADIAN/EUROPEAN ENSEMBLE MEANS DO NOT HAVE QUITE
AS MUCH EASTERLY COMPONENT AS THE GFS AND THE MANUAL GRAPHICS WILL
NOT SUPPORT THE WESTWARD MOVEMENT THIS MORNING. THE 12Z EUROPEAN
MODEL HAS NO CUTOFF LOW TO MOVE WEST AS IT KEEPS A SYSTEM MUCH
FARTHER NORTH THAN THE GFS.

THE ENSEMBLE MEANS ARE SHOWING A HIGHLY AMPLIFIED FLOW PATTERN
WITH A DEEP MEAN TROUGH BY DAY 6/MONDAY BECOMING NEGATIVELY TILTED
AND EXTENDING SOUTHEASTWARD FROM EASTERN ASIA TO THE NORTH CENTRAL
PACIFIC BY WEDNESDAY/DAY 8 AS THE UPPER HIGH BECOMES FIRMLY
ESTABLISHED NORTH OF THE BERING STRAIT. THIS CONFIGURATION OF
UPPER LEVEL FEATURES HELPS TO GENERATE A VERY STRONG HIGH PRESSURE
REGION FROM THE ARCTIC NORTH OF ALASKA SOUTHEASTWARD INTO NW
CANADA. COMBINED WITH THE LARGE AREA OF LOW PRESSURE OVER THE
NORTH CENTRAL TO NORTHWESTERN PACIFIC CREATES A LONG AND SUSTAINED
FETCH OF SURFACE EAST TO SOUTHEASTERLY FLOW FROM THE NORTHEAST
PACIFIC ACROSS THE BERING SEA BY LATE IN THE FORECAST.

SINCE THE 00Z EUROPEAN MATCHED WELL WITH THE 00Z UKMET...USED A
COMBINATION OF THOSE MODELS AS WELL AS A SMALL PORTION OF THE 12Z
GFS AND A SMALL CONTRIBUTION OF THE ENSEMBLE MEANS ON DAYS 4 AND
5/SATURDAY AND SUNDAY. WHILE BRIEFLY INCLUDING A SIMILAR BLEND OF
THE 00Z EUROPEAN WITH THE 12Z GFS ON MONDAY/DAY 6...WENT MORE WITH
THE 00Z EUROPEAN AND 00Z EUROPEAN AND NAEFS ENSEMBLE MEANS ON DAYS
7 AND 8/TUESDAY AND WEDNESDAY.

WHILE THE 12Z EUROPEAN JUST MAINTAINS A LARGE CUTOFF HIGH OVER THE
STATE BY THE END OF THE FORECAST WITH NO WESTWARD MOVING
TROUGH...THERE IS A DIFFERENCE WITH THE PREVIOUS RUN IN THAT A
SHORTWAVE MOVES EASTWARD ACROSS THE TOP OF THE RIDGE NORTH OF
ALASKA ON DAY 6/MONDAY. WHILE THIS SYSTEM DISRUPTS THE LARGE
ANTICYCLONE BRIEFLY IN THAT AREA...IT BUILDS DRAMATICALLY BEHIND
IT WITH A 1070 MB HIGH BY DAY 7/THURSDAY.

KOCIN

[srainhoutx]

E-mail from Jeff regarding the week ahead and beyond...

Dense fog blankets much of the area this morning behind the departing short wave from last night. Visibilities are running anywhere from 2 miles to 1/8th of a mile at most locations. Warm front is located along a line from Lake Charles to BUSH IAH to Victoria. Dense fog is widespread north of this boundary and then along the coast where sea fog is forming over the nearshore waters and bays. Surface wave over SE TX should progress eastward this morning allowing NW winds to develop and helping to clear out the drizzle and fog by late morning. A few showers are also noted on radar this morning over the coastal counties and these should be moving offshore and east of the area by mid morning.

Dry and seasonable weather for Thursday and Friday with lows in the 30’s and highs in the upper 60’s to near 70 by Friday.

Next big change arrives this weekend as the current cut-off low off of southern CA gets picked up by a trough moving into the Pacific NW and is then drug eastward across TX. Still dealing with model timing differences with this system, but looks like Saturday night into Sunday morning the area will be under the gun for widespread rainfall and possibly severe weather. Strong upper forcing from the upper level trough will develop surface low pressure late Saturday near Big Bend which will move ENE across TX Saturday night. A strong 35-40kt low level jet develops over the coastal bend Saturday afternoon transporting deep moisture northward into the region. Warm front will back northward toward the coast and likely move inland over SE TX allowing an unstable Gulf air mass to arrive just prior to the strong dynamics aloft. Numerous showers/thunderstorms are expected from Saturday afternoon/evening into Sunday morning. There is a threat for severe weather along and south of the warm front…so its position will be important come Saturday evening. With a strong low level jet below a 120kt mid level jet streak…there will be lots of wind energy that could be transported to the surface in downdrafts so severe winds look most likely, but would not rule out a few tornadoes if enough instability is available. Favorable backed wind profiles in the lower levels may help enhance this risk near/along the warm frontal boundary.

Next Week:

Models have backed off on the strong arctic air event for next week in their 00Z and 06Z runs, but will not fully bite on this downplaying of the event. Models typically have a very hard time resolving these outbreaks due to their shallow nature east of the Rocky mountains and it is more surprising how much agreement they have had over the past 2-3 days on this event. With that said, all models do continue to show a favorable delivery pattern for arctic air to enter the US Saturday and reach the southern plains by Sunday. 1048mb high is progged just north of the Montana border early next week with 1040mb pressures building into WC TX by Tuesday. Note that these pressures are about 10mb lower than what we were looking at 2 days ago suggesting the intensity of the arctic high may not be as strong. Passing weekend southern plains/TX storm system should help grab the shallow arctic air mass over the central plains and sling it rapidly southward on Sunday. Will toss out the model guidance for Monday in favor of the arctic air mass pushing southward under its own density and arriving to the TX coast by Monday afternoon/evening. Typically once these air masses get moving there is little to stop them. Will need to undercut the GFS guidance from Tuesday onward by at least 10 degrees on the afternoon highs as the model is just not grasping this air mass today as in previous runs. Will go with highs in the 40’s on Tuesday under strong cold air advection and then highs in the 30’s on Wednesday as the arctic dome becomes fully entrenched. Not sure how much clearing will take place behind the front as there does look to be a period of post frontal low stratus and this will help temper the overnight lows…so low 30’s on Tuesday morning to upper 20’s on Wednesday morning. Should clouds clear out…overnight lows will be about 5-8 degrees colder.

GFS attempts to completely erode the arctic dome by Thursday and Friday of next week as it spins up low pressure in the lee of the Rockies inducing southerly flow over TX. Once in place arctic cold domes are hard to dislodge, and suspect the model is moving the cold air too quickly eastward. GFS then crashes a secondary surge down the plains next weekend arriving around the 16/17 of the month.

As mentioned before we are not looking at anything historic or record breaking from this pending event, but a prolonged period of well below normal cold with potential for hard freezes over multiple days still looks likely. It remains questionable on how intense this outbreak may be and how long it will last. Stay tuned.

[ronyan]

I'm disappointed in the 0z models! Why does 12z always seem to be colder?
Meanwhile in Oymyakon, Russia it's -75F! http://www.wunderground.com/global/stations/24688.html
Canada, you need to tap into some of that cold air!

[brazoria121]

im guessing we will get some cold air but not anything record breaking and maybe a freeze or two in our northern counties probally..same ole same ole

[srainhoutx]

12Z GFS is rolling. I want to remind folks that we have a potential severe weather event unfolding over the weekend and I do not want folks to be caught off guard with that potential. AT hour 42, the GFS suggests that heights are rising across W AK(high pressure developing). We'll see what the run brings along with all the other guidance.

[Andrew]

Why is everyone going from one extreme to another? It was one model run. Things are still on track for some very cold, freezing weather. Let's see what the 12z has to offer.

[brazoria121]

andrew was it you that was saying the cold air was going to the east?

[Andrew]

andrew was it you that was saying the cold air was going to the east?

On that one run yes. Do I think the actual cold weather will go east? No. 12z is coming in stronger so far.