Good morning. The night crew remained active last night, I see. Busy day and not much time, but a highlight I would like to point out this early AM. While we may not see historic, News Headline cold
this coming week, it's looks to be very chilly and even cold for my standards. This weekend is a major concern regarding some very heavy rainfall and some possible severe weather. I'll let our severe weather folks provide the details regarding that. What catches my eye is the extreme cold building across Canada in the Medium range. I see some have already seen what the 06Z GFS offered. Looking at the 10 day+ ensemble means, an agreement is building for that extremely cold Arctic air mass to head S and spill into all the CONUS
next weekend +/- a day or two(Friday/14th-Saturday/15th). I found Forecaster Johnson of San Angelo NWS had the best explanation of the pattern ahead and all the players...the stepping down process is beginning, IMO...
LONG TERM...
AS THE UPPER LOW OFF THE CA COAST MOVES EAST OVER THE NEXT FEW
DAYS...SHORTWAVE RIDGE WILL PREVAIL OVER WEST TX. FRIDAY LOOKS TO BE
THE LAST PLEASANT DAY THAT WE WILL SEE FOR A WHILE BEFORE
PRECIP/COLD WEATHER COME INTO PLAY. HIGHS WILL BE IN THE 60S FOR THE
MOST PART WITH A FEW READINGS NEAR 70 DEGREES POSSIBLE IN THE
SOUTHERN HALF OF THE CWA. AS THE AFOREMENTIONED WAVE APPROACHES ON
SATURDAY...SURFACE CYCLOGENESIS WILL AID IN A RAPID NORTHWARD
MOISTURE TRANSPORT. DEWPOINTS ARE EXPECTED TO INCREASE INTO THE
MID/UPPER 40S ACROSS THE SOUTHERN ZONES BY SATURDAY AFTERNOON WITH
MID/UPPER 30S IN THE NORTH. MODELS ARE BEGINNING TO COME INTO
AGREEMENT WITH THE TRACK OF THIS UPPER LOW AS IT MOVES ACROSS THE
LONE STAR STATE. THE ECMWF IS MORE DYNAMIC THAT THE GFS WHICH
DEPICTS MORE OF AN OPEN WAVE BUT BOTH CLOSE OFF A MID LEVEL
CIRCULATION AS THE COASTAL TROF BEGINS TO DEVELOP. AHEAD OF THE
LOW...STRONG QG FORCING WILL PRIME THE ATMOSPHERE FOR MESOSCALE
ASCENT VIA WARM ADVECTION IN THE VICINITY OF THE WARM FRONT AND
STRONG MID LEVEL FRONTOGENETIC FORCING. QPF AMOUNTS SHOULD BE FAIRLY
SUBSTANTIAL FOR THIS TIME OF YEAR...ESPECIALLY ACROSS THE EAST BUT I
TEMPERED THE GUIDANCE OFFERED BY HPC AS IT WAS SUGGESTING WIDESPREAD
AMOUNTS OF WELL OVER 1 INCH. THUNDER HAS BEEN ADDED TO THE FORECAST
FOR THE SOUTHERN HALF OF THE AREA FROM 21Z SATURDAY THROUGH 12Z
SUNDAY. THE STRONG DYNAMICS SHOULD HELP OVERCOME THE LACK OF STRONG
INSTABILITY RESULTING IN THE LIKELIHOOD OF ELEVATED CONVECTION.
THE FORMATION OF A TROWAL ON THE BACKSIDE OF THE DEPARTING UPPER LOW
WILL KEEP THE MENTION OF LIGHT RAIN IN THE FORECAST THROUGH 18Z
SUNDAY. BUFR SOUNDINGS DEPICT THE COLUMN TO BE UNFAVORABLE FOR
WINTER PRECIP WITH THIS FEATURE AS TEMPS REMAIN ABOVE 0C THROUGH
AROUND 800MB AND NEAR SATURATION SO WET BULBING WOULD NOT DO THE
TRICK EITHER. HOWEVER THIS NEEDS TO BE WATCHED. NORTH WINDS EARLY
SUNDAY WILL BECOME EASTERLY DURING THE AFTERNOON WHICH SHOULD HELP
KEEP THE CLOUD COVER IN PLACE AND TEMPS IN THE 40S AND LOWER 50S.
THE THE ATTENTION TURNS TO THE BLAST OF ARCTIC AIR THAT HAS BEEN
DISCUSSED AD NAUSEUM FOR SEVERAL DAYS. I GUESS I SHOULD CONTINUE
THAT TREND.
THE SURFACE PRESSURES ACROSS NORTHWEST CANADA HAVE ONLY RISEN A FEW
MB SINCE THIS TIME YESTERDAY BUT THE BLOCKING RIDGE THAT IS EXPECTED
TO PRODUCE THE CROSS POLAR FLOW AND TAP INTO THE FRIGID SIBERIAN AIR
WILL CONTINUE TO BUILD ACROSS AK THROUGH THE WEEKEND. THIS SHOULD
RESULT IN A RAPID INTENSIFICATION OF THE ARCTIC HIGH BY SATURDAY.
THERE IS A DECENT AMOUNT OF SNOW COVER IN PLACE ACROSS ALL OF CANADA
AS WELL AS MUCH OF THE CENTRAL/NORTHERN PLAINS. THIS SHOULD PREVENT
THE AIRMASS FROM MODIFYING TOO QUICKLY AS IT HEADS SOUTH.
THE ACTUAL ARCTIC FRONT IS EXPECTED TO ARRIVE IN WEST CENTRAL TX
DURING THE DAY ON MONDAY. THIS IS JUST SLIGHTLY SLOWER THAN
PREVIOUSLY FORECAST BUT IS REALLY JUST SEMANTIC SINCE WE WILL HAVE
ALREADY EXPERIENCED THE INITIAL FROPA /ON SUNDAY/ AND WILL ALREADY
BE BELOW RATHER COOL. HOWEVER...AS THIS FRONT ARRIVES TEMPS WILL
DROP ANOTHER 15-20 DEGREES. THE GFS IS FASTER THAN THE 00Z RUN
YESTERDAY AND IS FAIRLY SIMILAR TO THE ECMWF. THE GEM STANDS OUT AT
AS THE FASTEST WITH THE COLD AIR PAST INTERSTATE 10 BY 12Z. I AM
SLIGHTLY FASTER THAN THE GFS BUT NOT AS FAST THE GEM. TEMPS SHOULD
TOP OUT NEAR 40 IN THE NORTH TO THE LOWER 50S ALONG I-10 BUT WILL
QUICKLY FALL ONCE THIS FRONT ARRIVES. I CONTEMPLATED PUTTING THE
LIGHT SNOW BACK IN THE FORECAST FOR THE BIG COUNTRY BUT OPTED NOT TO
FOR NOW SINCE I THINK THAT IT WILL MAINLY BE IN THE FORM OF FLURRIES
WITH NO ACCUMULATIONS EXPECTED. OTHERWISE...COLD AND BLUSTERY
CONDITIONS ARE EXPECTED MONDAY AND MONDAY NIGHT.
THE GFS IS MORE PROGRESSIVE WITH THE MID WEEK WAVE AND ERODES THE
COLD AIR MORE QUICKLY THAN I WOULD LIKE. FOLLOWING THE ECMWF PATTERN
MORE CLOSELY...THE NEAR 1050 MB SURFACE HIGH SHOULD BUILD DOWN THE
PLAINS HUGGING THE FRONT RANGE AS A BARRIER JET DEVELOPS IN THE LEE
OF THE ROCKIES. THE SURFACE-H7 FLOW REMAINS PREDOMINANTLY FROM THE
NORTH THROUGH EARLY WEDNESDAY WHICH WOULD KEEP THE COLD AIR FLOWING
SOUTH. THIS REINFORCEMENT OF THE COLD AIRMASS WILL PREVENT LEE
CYCLOGENESIS FROM SCOURING IT OUT TOO QUICKLY. HIGHS ARE EXPECTED TO
BE MAINLY IN THE 30S TUESDAY/WEDNESDAY ALTHOUGH WE COULD START TO
SEE SOME MODIFICATION INTO THE 40S BY WEDNESDAY. A MODEST WARM UP IS
EXPECTED TOWARD THE END OF THE WEEK BUT WE CONTINUE TO SEE A
EAST/WEST ORIENTED TROF EXTENDING ACROSS THE NORTHERN LATITUDES FROM
THE HUDSON BAY VORTEX WITH ADDITIONAL ARCTIC AIR BOTTLED UP OVER
NORTHWEST CANADA READY TO HEAD SOUTH. THIS POINTS TO ANOTHER BLAST
EITHER NEXT WEEKEND OR EARLY THE FOLLOWING WEEK.
JOHNSON
GFS Ensemble Plot 276 Hours
01062011 00Z GFS Ensemble Spagetti.gif
Euro Day 10 Ensemble/500mb
01062011 00Z Euro Ensemble Day Ten 500mb Geopotential32at32500hPa_North32America_240.gif
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I have four alarms set so if I fall asleep I will roll out of bed, grumble and head to the coffee house and catch up on the weather. 
You know, I was just trying to think of that today myself. I don't recall that happening either. I do however remember some extensively destructive fall/winter severe wx outbreaks in H-Town. First one I ever experienced was on November 17th of 2003. SPC received 32 preliminary tornado reports all within the Houston metro area and surrounding suburbs. Supercells started at about 9 that morning and kept dropping twisters until about 6 that evening, along with very heavy rain, causing flooding and requiring high water rescues. Between my memories of Dallas and Houston...that Houston outbreak was the worst I had been through...and now that I know the statistics of how many tornadoes we have had on record here in Harris co., vs. Dallas co., I understand why. Harris county has a lot more tornadoes on record than Dallas county...nearly 3x the number of Dallas. Both Houston's and Dallas' strongest twisters were F4's. Harris co. total count = 213 Dallas co. count = 86, on record from 1950 - 2009. The F4 occured in Channelview in November 1992...probably the worst tornado outbreak we've had. In December of 2002, SPC put Houston in the rare High risk category for extreme damaging winds. Wacky stuff!
