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Texas/MX Obs And Discussion Thread.


Srain

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What you are describing seems to be a bit like what the 18z GFS shows in the long run, I think...

The past few runs of the GFS and Euro have had some major blocking and large high pressures building across Northern Canada. If we could just get the Pacific to relax, as you say...

Oh, so you're awake now?:pepsi:

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Up and ready, sir

The 0z GFS likes wxmx's idea of a pattern change in the Pacific just before Chrimbus...

18 and 0z runs liked it...but 06z didn't... all models show the very negative AO/NAO, and the migration of the high heights towards Nern Canada, but the Pacific pattern isn't going anywhere unless there's a change in the tropical forcing areas near Indonesia, which are feeding with constant lows the GOA. MJO is transiting thru phase 5 towards phase 6, and will probably get close to phase 7, but models show it entering the circle of death thereafter :(.

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Some may disagree, but there are signals or 'hints' to a colder pattern setting up in our area near Christmas, +/- several days. We have seen the GFS occasionally spit out some solutions in the longer range suggesting this. What is catching my eye is the tanking AO, NAO and some hints of the PNA cooperating in the Pacific. The fly in the ointment is the Gulf of Alaska Low that has been present all season. If that feature can shift W, the door could open for some mighty cold air to spill S along the front range of the Rockies and not pass us in a glancing fashion as we have seen of late. Just something to watch and see if it pans out.

AO near record negative levels (Blocking pattern)...

ao.sprd2.gif

NAO remaining negative to near neutral...

nao.sprd2.gif

PNA rising from negative to slightly positive (suggests ridging building in the NE Pacific)...

pna.sprd2.gif

00ZGFS 12/11/2010 Long Range...(Pacific View(500mb) CONUS View (850mb))

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Fingers crossed as the the GFS, Canadian and Euro suggest a short wave embedded in the Polar Jet with some Pacific moisture will move across the area this weekend and perhaps bring a chance of light rain for our area. Further N, perhaps even some wintry precip. This feature may be on the way to being a big East Coast snow event as it wraps up along the EC. We shall see...

HPC:

PRELIMINARY EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

829 AM EST MON DEC 13 2010

VALID 12Z FRI DEC 17 2010 - 12Z MON DEC 20 2010

...PRELIMINARY UPDATE...

USED THE 00Z ECMWF TO UPDATE THE FRONTS AND PRESSURES FOR DAYS 3

AND 4...WITH A GRADUAL TRANSITION TO THE 06Z GEFS MEAN BY DAY 6.

THE BLOCKY REGIME IS INDICATED TO HOLD THROUGH THE PERIOD BY ALL

THE MODELS...WITH A SUPPRESSED POLAR JET ACROSS THE ENTIRE NATION.

HEIGHTS WILL BE THE GREATEST OVER THE SOUTHERN HIGH PLAINS WHERE

THE SUBTROPICAL RIDGE WILL BE ABLE TO HERNIATE NORTHWARD. THE

DETAILS OF THE ENERGY COMING INTO THE WEST COAST ARE WILDLY

UNCERTAIN...BUT THERE IS ENOUGH AGREEMENT BETWEEN THE ENSEMBLE

MEANS FROM THE VARIOUS MODELING CENTERS TO SUPPORT THE BLEND USED

FOR THIS FORECAST PACKAGE. THE SITUATION ALONG THE EAST COAST IS

FAR MORE CONTENTIOUS...WITH THE 00Z AND 06Z GFS RUNS BOTH BRINGING

A MAJOR SNOWSTORM TO THE MID ATLANTIC AND NORTHEAST DAYS 6 AND 7.

THE 00Z ECMWF KEEPS THE NORTHERN STREAM DOMINANT OVER THIS

REGION...AS DOES THE GEM GLOBAL. HOWEVER...THE 12Z/12 AND 12Z/11

RUNS OF THE ECMWF BOTH SHOWED THE SNOWSTORM. OPTED TO GO WITH THE

06Z GEFS MEAN FOR THIS POTENTIAL EVENT...WHICH AT LEAST BRINGS A

CYCLONE NORTHWARD OVER THE WESTERN ATLANTIC...JUST FARTHER

OFFSHORE AND WITH LESS ISOBARIC COMMITMENT...IF YOU WILL. THIS

CHOICE LEAVES ROOM FOR TRENDING EITHER WAY.

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Fingers still crossed that this works out no matter how meager (or what DT says) regarding the amount of moisture for our drought parched area...

HGX:

A NORTHERN TEXAS PASSING SHORTWAVE DISTURBANCE MID TO LATE FRIDAY

APPEARS TO HAVE ENOUGH DOWNSTREAM MOISTURE AND WARM AIR THERMODYNAMICS

TO INTRODUCE A MODEST CHANCE FOR WIDELY SCATTERED SHOWERS. A COLD

FRONTAL PASSAGE EARLY ON FRIDAY WILL PUSH A SHALLOW COOL DOME OF

AIR OVER THE REGION...OVERRUNNING MID-LEVEL SW`ERLIES INITIATING

DECENT ENOUGH ISENTROPIC LIFT TO GENERATE RAIN SHOWERS. MODERATE

CHANCE POPS OVER THE CENTRAL AND SOUTHERN FA AS THE PASSING

SHORTWAVE/EFFICIENT WAA INCREASES THE PROB OF MAINLY LIGHT QPF

SHOWERS. ANY RAIN WILL BE WELCOME IN THE MIDST OF THIS DROUGHT....

UNFORTUNATELY JUST A FEW HUNDREDTHS TO COUPLE OF TENTHS OF AN INCH

TOTALS WILL BE THE MOST MANY RECEIVE THROUGH EARLY SATURDAY

MORNING.

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broke out the shorts again today. gotta get some use out of them before i leave tomorrow.

surprisingly warm 72F at easterwood right now with full sun. would feel perfect if there weren't gusts to 25mph.

Have a safe trip home. Hopefully a pattern change is in the works for the end of December and we will be done with this dry pattern as we head toward the New Year, however brief it may be.:whistle:

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Have a safe trip home. Hopefully a pattern change is in the works for the end of December and we will be done with this dry pattern as we head toward the New Year, however brief it may be.:whistle:

so nice to end it on a gorgeous day. 75F and sunny this afternoon.

only problem is that darn wind. gusting to 30mph here.

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Have a safe trip home. Hopefully a pattern change is in the works for the end of December and we will be done with this dry pattern as we head toward the New Year, however brief it may be.:whistle:

Will the pattern change be no more GOA low, or will it be no more high latitude blocking? That's the 64k question. Very different outcomes for us down south.

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Heads up on a possible event days 10-13. Both 12z GFS and Euro show strong energy ejected from the W coast low (finally). With still some high latitude ridging in N Canada and the possibility of some ridging in the W Coast, some wintry conditions are possible in the S plains.

Euro day 10

12zECMWF500mbHeightAnomalyNA240.gif

GFS day 10.5

12zGFS500mbHeightAnomalyNA252.gif

GFS ensembles day 13

12zGFSEnsembles500mbHeightAnomalyNA300.gif

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Nice to see the guidnace finally 'hinting' at that change we have all been look forward to. When Jorge gets onboard, look out! :pimp:

Thanks Steve.

Other than modeling, there are also some teleconnectors. AO and NAO will remain negative, probably not severely so, but enough to keep cold canadian air sipping south. The equator teleconnections aren't that positive, but they will become less negative. The MJO is entering to the circle of death... by itself isn't a positive signal for cold/wet, but at least is out of the dreaded 4-6 phases.

bmo.mjo.latest.png

Also, -OLR anomalies near Indonesia are forecasted to decrease slightly. This might induce some changes in tropical forcing with subsequent Rossby waves position alteration...specially in W North America.

spatial_olrmap_full.gif

I don't think there will be a real pattern change, since the main teleconnector (ENSO) will remain stable borderline strong, but more of a transitory change.

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