February 1-5, 2011 Arctic Blast/Winter Storm Discussion

[harpman]

Shoot! I can't get you tube vids through my work puter! Briefly, what does it say?

Srain, check PM.

Harpman, the main thrust of the cold air will be south rather than east. I don't think there's any winter precip risk for New Orleans. Coldest temps this time will be along the TX coast to southwest LA. Just cool/cold rain for southeast LA.

Thanks. I will continue to watch and monitor.

[Mr. T]

In Jan 2010, IAH reached 20 with surrounding obs around 16. I would think we'd be at least few degrees cooler than that if you take the 12z Euro or CMC verbatim... The airmass is shown to be several degrees colder in the upper levels than the 2010 event...

Of course, who knows if these wacky runs verify anyway...

[srainhoutx]

FYI: More Pacific Winter RECON ahead for Sunday...

NOUS42 KNHC 271700
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1200 PM EST THU 27 JANUARY 2011
SUBJECT: WINTER STORM PLAN OF THE DAY (WSPOD)
VALID 28/1100Z TO 29/1100Z JANUARY 2011
WSPOD NUMBER.....10-058

I. ATLANTIC REQUIREMENTS
1. NEGATIVE RECONNASSSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.

II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS
2. SUCCEEDING DAY OUTLOOK:
A. P73/ 43.9N 172.3E(DROP 11)/ 30/1200Z

[Andrew]

Hey Wxman what do you think about the possibility of freezing roads? ECMWF has the precip ending right when the freezing temps settle in but how concerned are you about the re freeze of that moisture that had already fallen?

[wxman57]

Keeping up with the Houston NWS office forecast. They appear to be going straight with the GFS temps, or warmer. I agree it's too early to actually forecast low 20s, but I think that there's a very good chance Wednesday's high will be at least 10 degrees colder, along with a low closer to 29-30 rather than 39.

INCLUDING THE CITIES OF...HOUSTON...HUMBLE...KATY...PASADENA...
TOMBALL
1006 AM CST THU JAN 27 2011

MONDAY NIGHT AND TUESDAY...MOSTLY CLOUDY WITH A 40 PERCENT
CHANCE OF SHOWERS. LOWS IN THE LOWER 50S. HIGHS IN THE UPPER 60S.

TUESDAY NIGHT AND WEDNESDAY...MOSTLY CLOUDY WITH A 20 PERCENT
CHANCE OF SHOWERS. COOLER. LOWS IN THE UPPER 30S. HIGHS AROUND
50.

[wxman57]

Hey Wxman what do you think about the possibility of freezing roads? ECMWF has the precip ending right when the freezing temps settle in but how concerned are you about the re freeze of that moisture that had already fallen?

I'm not thinking that will be an issue anywhere around here. Once the precip stops the area should dry out fairly quickly as high pressure builds in.

[srainhoutx]

There is still a lot of spread in the Euro Ensemble mean, folks. The free Euro site has the images, but I will wait on Allan's graphics. They suggest some energy still to our SW after the front (hours 144/168), for what it's worth.

[biggerbyte]

Just to recap. Folks, we still need to give this until Saturday, or even early Sunday. Things look cold, but it remains to be seen if we will get temps we have not already had. One thing that looks a tad more promising is available moisture, along with a the trigger that we've been talking about for a few days. One thing, newbies. I've mentioned before... that it only needs to be cold enough to get some wintry fun. More in a day or two. I really hope we can get verification. I want some bone popping cold, and just enough winter precip. to do something with, and be pretty.

[Andrew]

All we need is to have the Euro's cold and speed matched up with the GFS's moisture and we will have a winter miracle.

[wxman57]

All we need is to have the Euro's cold and speed matched up with the GFS's moisture and we will have a winter miracle.

One big problem I see is that the really cold air doesn't come down until later on Wednesday and on Thursday, long after the precip has ended Tuesday afternoon/evening. Current air temps in BC and Alberta are in the 40s and 50s. You have to look well north in the central to northern Northwest Territory to find below zero temps. Temps in BC and Alberta were -20 to -40F just about a week ago, but that air has modified significantly. Combine that with the fact that the snow line is now way up into northern KS and Nebraska, meaning a greater modification of the initial surge. So the initial surge on Tuesday will probably not be cold enough to give us any real shot at winter precip.

[Andrew]

All we need is to have the Euro's cold and speed matched up with the GFS's moisture and we will have a winter miracle.

One big problem I see is that the really cold air doesn't come down until later on Wednesday and on Thursday, long after the precip has ended Tuesday afternoon/evening. Current air temps in BC and Alberta are in the 40s and 50s. You have to look well north in the central to northern Northwest Territory to find below zero temps. Temps in BC and Alberta were -20 to -40F just about a week ago, but that air has modified significantly. Combine that with the fact that the snow line is now way up into northern KS and Nebraska, meaning a greater modification of the initial surge. So the initial surge on Tuesday will probably not be cold enough to give us any real shot at winter precip.

Still though GFS and Euro seem to have some type of precip into the morning Wednesday. Even the slightest adjustment in speed from the cold air coming down to the low could create the biggest impacts. I don't think we have a chance at snow as all levels won't be freezing at the time but I do think we have somewhat of a shot at sleet/ freezing rain. I am just hoping the euro and cmc are still to slow with the progression of the front.

[srainhoutx]

Afternoon Update time from the NWS TX Offices...

Dallas/Ft Worth:

BY SUNDAY...A STRONG RIDGE OF HIGH PRESSURE WILL DEVELOP OVER
WESTERN CANADA...ONCE AGAIN OPENING UP THE DOOR FOR ANOTHER ARCTIC
AIRMASS. A PIECE OF COLD AIR ASSOCIATED WITH THE MAIN POLAR VORTEX
IN NE CANADA WILL BREAK OFF AND ENTER THE NORTHERN US BY
MONDAY...SENDING A SHALLOW ARCTIC AIRMASS SOUTHWARD INTO THE
SOUTHERN PLAINS. THIS SYNOPTIC SETUP IS FAVORABLE FOR A VERY COLD
AIRMASS TO BE IN PLACE ACROSS NORTH TEXAS BY TUESDAY MORNING. THE
GFS IS CURRENTLY THE WARMEST OF THE MEDIUM RANGE GUIDANCE...BUT DO
NOT PUT MUCH WEIGHT INTO ITS SURFACE TEMPERATURE FORECAST. THIS
FAR OUT...MODELS TEND TO HAVE PROBLEMS HANDLING THE SHALLOW DEPTH
OF ARCTIC AIRMASSES AND ONE NEEDS TO PAY CLOSER ATTENTION TO THE
OVERALL SYNOPTIC PATTERNS AND BASE A TEMPERATURE FORECAST FROM
PAST EXPERIENCES. CURRENT 850 TEMPS IN THE SOURCE REGION ARE IN
THE NEGATIVE 24C RANGE AND ALL MEDIUM RANGE MODELS HAVE 850 TEMPS
IN SOUTHERN CANADA NEAR -20C BY SUNDAY AFTERNOON. THESE
TEMPERATURES COMPARED TO THE TEMPERATURES FROM THE LAST ARCTIC
AIRMASS ARE ACTUALLY COLDER WHEN WE SAW PROLONGED SURFACE
TEMPERATURES BELOW FREEZING IN NORTH TEXAS. AGAIN...THE GFS SEEMS
TO BE TOO SLOW AND TOO WARM WITH THE AIRMASS AND WILL STICK CLOSER
TO THE COLDER CANADIAN AND ECMWF SOLUTIONS.

MEANWHILE...A PIECE OF ENERGY FROM THE NORTHERN PACIFIC IS PROGGED
BY ALL MODELS TO ENTER TEXAS SOMETIME EARLY NEXT WEEK. THERE ARE
MANY UNCERTAINTIES REGARDING HOW THIS TROUGH WILL MOVE THROUGH THE
REGION AND WHAT IF ANY WINTER WEATHER IMPACTS IT MAY HAVE. THERE
ARE BASICALLY TWO DIFFERENT CAMPS IN THE GUIDANCE WITH HOW THIS
MAY PLAY OUT. THE GFS/ECMWF ARE MUCH SLOWER WITH THE PROGRESSION
OF THE TROUGH AND PROG A TUESDAY ARRIVAL. THIS ALLOWS AMPLE TIME
FOR THE COLD AIR TO BE IN PLACE BEFORE THE LIFT ARRIVES AND BOTH
SOLUTIONS WOULD FAVOR A SIGNIFICANT WINTER WEATHER EVENT FOR MUCH
OF NORTH TEXAS. THE CANADIAN/NOGAPS/UKMET PROG A MUCH STRONGER
PIECE OF THE POLAR LOW TO SET UP ACROSS THE NORTHERN PLAINS BY
MONDAY NIGHT. IF THIS WERE TO OCCUR...OUR PACIFIC PIECE OF ENERGY
WOULD QUICKLY BE SWEPT UP AROUND THE BIGGER SYSTEM AND ALL THE
LIFT ASSOCIATED WITH THE DISTURBANCE WOULD BE GONE BEFORE THE COLD
AIR ARRIVES. THE PRECIP WOULD REMAIN MOSTLY LIQUID...ENDING BY
TUESDAY MORNING. HOWEVER...AFTER THE PRECIP ENDS...VERY COLD
TEMPERATURES WOULD THEN MOVE INTO THE REGION AND LOWS IN THE
SINGLE DIGITS WOULD BE POSSIBLE ACROSS THE NORTHERN ZONES THURSDAY
MORNING IF THIS WERE TO VERIFY. IT SHOULD BE NOTED THAT THE LATTER
GROUP OF MODELS IS NOT USUALLY THE PREFERRED SET WHEN WE MAKE A
FORECAST...BUT GIVEN THAT THERE ARE SOME SLIGHT DIFFERENCES EVEN
WITH THE GFS/ECMWF AND HOW SIMILAR THIS GROUP IS...SOME WEIGHT
DEFINITELY IS GIVEN TO THIS DATA SET.

FOR NOW...WE WILL CONTINUE TO INDICATE IN OUR OFFICIAL FORECAST
THE POSSIBILITIES OF WINTER WEATHER ON TUESDAY. REGARDLESS...VERY
COLD AIR SEEMS LIKELY NEXT WEEK...BUT THE QUESTION REMAINS...WILL
WE SEE PRECIP AFTER THE COLD AIR ARRIVES. IF FROZEN PRECIPITATION
WERE TO FALL...WE FEEL THE MOST LIKELY PRECIP TYPE WOULD BE
FREEZING RAIN AND SLEET. GIVEN THE SHALLOW DEPTH OF THE COLD AIR
AND THAT THE SOURCE OF LIFT WILL BE AN OPEN ENDED TROUGH...SNOW
WILL NOT BE LIKELY INITIALLY. IF PRECIP WERE TO LINGER LONGER THAN
EXPECTED...WE COULD SEE A FINAL CHANGEOVER TO SNOW BEFORE
EVERYTHING SHUTS OFF.


Corpus Christi:

.LONG TERM (SATURDAY THROUGH WEDNESDAY)...THE UPPER LOW CURRENTLY
WEST OF BAJA WILL BE RE-ABSORBED INTO THE MAIN FLOW OVER THE NEXT
FEW DAYS. THE SYSTEM WILL OPEN UP AND WEAKEN SOME...BUT IS PROGGED
TO REMAIN A VIGOROUS S/WV AS IT MOVES ACROSS CEN TEXAS SATURDAY
NIGHT. A NICE TAP OF HIGHER MOISTURE ACROSS THE WRN GULF WILL ADD
FUEL FOR ANOTHER JANUARY RAIN EVENT ACROSS THE STATE. MODELS HAVE
WAFFLED WRT THE STRENGTH AND TRACK OF THE LOW...AND HAVE DRIFTED A
BIT NORTH IN THE PAST FEW RUNS...BUT STILL SHOW STRONG LIFT AND GOOD
MID LEVEL COOLING SPREADING ACROSS S TX MAINLY LATE SAT AND SAT
NIGHT. SSW H85 WINDS SUGGEST BEST MOISTURE TRANSPORT WILL OCCUR
ACROSS NERN AREAS AND INTO THE ERN HALF OF THE STATE...BUT THE UPR
DYNAMICS ARE STRONG ENOUGH THAT THE TAIL END OF THE ACTIVITY SHOULD
STILL IMPACT EVEN SRN/SWRN AREAS THE REGION. THINK THE GFS IS TOO
FAST WITH THE SYSTEM AND HAVE SIDED W/ THE SLOWER ECMWF/NAM. THIS
MEANS THE HIGHEST POPS WILL BE SAT NIGHT AND AM ONLY SHOWING LOW CHC
FOR SAT...THEN SCT-LIKELY POPS (FAVORING NE ZONES) SUN NIGHT. THE
TAIL END OF THE PRECIP MAY VERY WELL END UP IN OUR SRN CWA. A
POTENTIAL FOR TSTMS REMAINS AS WELL...ESP IN NRN AREAS WHERE
STRONGEST MID LEVEL COOLING ASSOC W/ THE LOW OCCURS.

ADDITIONAL STRONG S/WVS WILL MOVE OVER A WEST COAST/PACIFIC RIDGE
DIGGING ACROSS THE WRN US EARLY NEXT WEEK. THIS CARVES A DEEP
POSITIVELY TILTED TROUGH ACROSS THE MID SECTION OF THE COUNTRY BY TUE.
THE HIGHLY AMPLIFIED JET PATTERN WITH STRONG RIDGING UP THE WEST
COAST AND DEEP TROUGH ACROSS THE PLAINS WILL ALLOW AN ARCTIC FRONT
TO SPILL SOUTH NEXT WEEK. THE FRONT WILL AND UPR S/WVS WILL PROVIDE
ADDITIONAL RAIN CHANCES EARLY NEXT WEEK WITH MUCH COLDER
TEMPERATURES SPILLING INTO THE REGION BY TUE...BUT ESP INTO WED WHEN
HIGHS MAY STRUGGLE TO REACH THE 40S. AGAIN MODELS ARE HAVING SERIOUS
ISSUES DEALING W/ DETAILS OF THE STRENGTH OF THE FRONT AND THE
ARCTIC HIGH...AS WELL AS WHETHER IT WILL BE WET BEHIND THE FRONT OR
DRY OUT IMMEDIATELY. THINK AT LEAST WED WILL REMAIN DAMP SIMILAR TO
THE GFS PROGS OVER THE LAST FEW DAYS. TOUGH AT THIS POINT TO SAY
WHETHER WE WILL SEE A FREEZE GIVEN ALL THE UNCERTAINTY...BUT THE
GENERAL COLD PATTERN FOR THE MIDDLE TO END OF THE WEEK SEEMS LIKELY.

[srainhoutx]

12Z Euro Ensemble 500mb/Temps Anomalies...

[weatherguy425]

HGX:

CLEARING ON SUNDAY WITH THE NEXT IN-A-LINE OF WESTERN DISTURBANCES
GETTING WOUND UP OVER THE DESERT SW LATE SUNDAY THROUGH MONDAY.
THIS IS WHERE THE GFS AND ECMWF SIGNIFICANTLY DIFFER. THE CHANCE
OF RAIN REMAINS HIGH ON TUESDAY FROM MAINLY SW`ERLY VORTS KICKING
OUT FROM UNDER THIS DEVELOPING WESTERN TX TROF. THE MORE AGGRESSIVE
EURO DIGS THE 5H TROF OVER EASTERN TEXAS WHILE THE MORE PASSIVE
GFS SHUNTS ENERGY TO THE NORTH AND KEEPS A ZONAL FLOW OVER TEXAS
AT MID-WEEK. THE MOST GLARING DIFFERENCE WILL BE IN TEMPERATURES.
THE EURO HAS A NEAR -10C 85H AIR MASS SPILLING OVER THE REGION
WEDNESDAY...WHILE THE GFS HAS THE 85H 0C LINE ONLY REACHING THE
RED RIVER VALLEY DURING THE SAME PERIOD. A VERY MINOR MENTION OF
OF A WINTRY MIX WAY UP UP NORTH LATE TUE/EARLY WED MORNING AS
THERE MAY BE ENOUGH LINGERING MOISTURE WITHIN A SIGNIFICANTLY
COOLING COLUMN. OBVIOUSLY WAY TOO EARLY AND SIMPLY SPECULATION...
BUT THE SUNDAY THROUGH WEDNESDAY TIME PERIOD APPEARS TO HAVE IT
ALL...FROM THE PROBABILITY OF HEAVY RAIN TO SIGNIFICANT
TEMPERATURES PLUMMETS BY THIS TIME NEXT WEEK. 31

[Big O]

12Z Euro Ensemble 500mb/Temps Anomalies...

Steve, what are those Lows in NE Mexico to the west and northwest of the lower RGV, as depicted in the European ensemble mean? Are they signaling that some of the ensemble members actually have a low pressure area over NE Mexico progged to move eastward into Texas by Wednesday?

[tireman4]

HGX:

CLEARING ON SUNDAY WITH THE NEXT IN-A-LINE OF WESTERN DISTURBANCES
GETTING WOUND UP OVER THE DESERT SW LATE SUNDAY THROUGH MONDAY.
THIS IS WHERE THE GFS AND ECMWF SIGNIFICANTLY DIFFER. THE CHANCE
OF RAIN REMAINS HIGH ON TUESDAY FROM MAINLY SW`ERLY VORTS KICKING
OUT FROM UNDER THIS DEVELOPING WESTERN TX TROF. THE MORE AGGRESSIVE
EURO DIGS THE 5H TROF OVER EASTERN TEXAS WHILE THE MORE PASSIVE
GFS SHUNTS ENERGY TO THE NORTH AND KEEPS A ZONAL FLOW OVER TEXAS
AT MID-WEEK. THE MOST GLARING DIFFERENCE WILL BE IN TEMPERATURES.
THE EURO HAS A NEAR -10C 85H AIR MASS SPILLING OVER THE REGION
WEDNESDAY...WHILE THE GFS HAS THE 85H 0C LINE ONLY REACHING THE
RED RIVER VALLEY DURING THE SAME PERIOD. A VERY MINOR MENTION OF
OF A WINTRY MIX WAY UP UP NORTH LATE TUE/EARLY WED MORNING AS
THERE MAY BE ENOUGH LINGERING MOISTURE WITHIN A SIGNIFICANTLY
COOLING COLUMN. OBVIOUSLY WAY TOO EARLY AND SIMPLY SPECULATION...
BUT THE SUNDAY THROUGH WEDNESDAY TIME PERIOD APPEARS TO HAVE IT
ALL...FROM THE PROBABILITY OF HEAVY RAIN TO SIGNIFICANT
TEMPERATURES PLUMMETS BY THIS TIME NEXT WEEK. 31

Thus proving Wxman57 right again. He stated they would go conservative until they really got a handle on this. I am thinking Saturday or Sunday before they commit.

[Mr. T]

Hgx going with lows in the upper 20s next week. They are going several degrees below gfs guidance

[Mr. T]

One big problem I see is that the really cold air doesn't come down until later on Wednesday and on Thursday, long after the precip has ended Tuesday afternoon/evening. Current air temps in BC and Alberta are in the 40s and 50s. You have to look well north in the central to northern Northwest Territory to find below zero temps. Temps in BC and Alberta were -20 to -40F just about a week ago, but that air has modified significantly. Combine that with the fact that the snow line is now way up into northern KS and Nebraska, meaning a greater modification of the initial surge. So the initial surge on Tuesday will probably not be cold enough to give us any real shot at winter precip.

Looks to me like the source of this potential arctic outbreak will be over Central and Eastern Canada. Similar to the Jan 85 events but a bit warmer...

[tireman4]

Hgx going with lows in the upper 20s next week. They are going several degrees below gfs guidance

I was thinking more in terms of P-Type...but I could be wrong...LOL

[cristina99]

i am not on the board for a few hours and look what happens. Has the cold air gone away? I wish SUnday would get here so we would know what's going to happen. How could the cold air be there one minute, then go away the next?