November Weather Discussion. Rollercoaster Pattern.

[srainhoutx]

Getting to the range where we can start looking at some shorter range ensemble data. Tonights version of the SREF Ensembles for 18Z Thanksgiving Day 2 meter temps and winds...

[wxman57]

Not much change overnight. 06Z GFS brings the front through right before 3PM Thursday. Note the 12PM temp of 76 and the 3PM temp of 72. That says frontal passage occurs just a few minutes before 3PM Thursday, as the temp has just started to fall at 3PM. It'll fall VERY fast when the front arrives, probably 20 deg the first hour. No freeze indicated by the latest model runs, and up into the low 50s for highs Friday.

[srainhoutx]

So it is the GFS versus the Euro/NAM (6+ hours slower) solution regarding the timing if the Arctic Front. Watch them all be wrong.

HPC:

SHORT RANGE FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
324 AM EST TUE NOV 23 2010

VALID 12Z TUE NOV 23 2010 - 12Z THU NOV 25 2010

QUITE THE EVENT IS UNFOLDING ACROSS THE WESTERN U.S. WITH A
VARIETY OF WINTER PRECIPITATION-RELATED WATCHES AND WARNINGS
CURRENTLY IN EFFECT. THE MOST HAZARDOUS EFFECTS SHOULD REMAIN
CONFINED TO THE MOUNTAINOUS REGIONS ALTHOUGH THE EXTREMELY COLD
AIR IN PLACE HAS BROUGHT SNOWFALL TO COASTAL LOCALES IN THE
PACIFIC NORTHWEST AS WELL. REGARDLESS...WINTER STORM AND BLIZZARD
WARNINGS CURRENTLY BLANKET THE WESTERN U.S. AS A STRONG UPPER
TROUGH ADVANCES THROUGH THE REGION THE NEXT 36 TO 48 HOURS. THE
BIGGEST PLAYER IS A POWERFUL CLOSED LOW PUSHING AWAY FROM
WASHINGTON STATE WHICH WILL DRIVE ANOTHER SURGE OF ARCTIC AIR TO
THE COUNTRY. VERTICAL LIFT ACCOMPANYING THIS VORTEX WILL HELP
PRODUCE MODERATE SNOWFALL TO THE INTERIOR WEST WITH THE
TETONS...WASATCH...SAN JUANS...AMONG OTHERS GETTING IN ON THE
ACTION THROUGH WEDNESDAY NIGHT. ONCE THE FRONTAL BOUNDARY PUSHES
OUT INTO THE GREAT PLAINS BY WEDNESDAY EVENING...FRIGID AIR WILL
FILL THE WESTERN STATES WITH HIGHS ON WEDNESDAY STRUGGLING TO GET
OUT OF THE SINGLE DIGITS ACROSS THE NORTHERN ROCKIES AND UPPER
INTERMOUNTAIN WEST. THE EFFECTS WILL EVEN MORE NOTICEABLE AT NIGHT
AS LOWS PLUMMET DOWN WELL INTO THE NEGATIVE TEENS WITH EVEN SOME
READINGS APPROACHING -20 OVER WESTERN MONTANA. AS THIS FRONTAL
BOUNDARY RACES OFF TO THE EAST...THE COLD AIR WILL EVENTUALLY
REACH THE CENTRAL U.S. AS 20S LURK BEHIND THE FRONT AND 60S AND
70S REMAIN DOWNSTREAM.

AN UPPER DISTURBANCE TREKING ACROSS THE UPPER MIDWEST AND INTO THE
GREAT LAKES REGION IS BRINGING UNSETTLED CONDITIONS ALONG ITS
ASSOCIATED FRONTAL BOUNDARY. HOWEVER...THE COVERAGE AND INTENSITY
OF THE PRECIPITATION WILL DIMINISH IN NATURE AS THE BEST UPPER
FORCING RACES OFF TOWARD CANADA. THERE WILL BE A DEFINITE CHANGE
IN THE WEATHER AS 60S ALONG THE EAST COAST ARE REPLACED WITH 50S
FOR THE MIDDLE OF THE WEEK. HOWEVER...EVEN COLDER AIR LURKS OFF TO
THE WEST AS THE POTENT WESTERN SYSTEM ADVANCES INTO THE GREAT
PLAINS. AHEAD OF THIS SYSTEM...THERE WILL BE AN INCREASE IN THE
MOISTURE DRAWN UP FROM THE GULF OF MEXICO. THIS WILL ASSIST IN THE
DEVELOPMENT OF OVERRUNNING PRECIPITATION NORTH OF THE WARM FRONT
WITH THE INTENSITY PICKING UP WEDNESDAY AFTERNOON/EVENING.




Also of note is the temp gradiant across TX this morning. This is not due to the Arctic Boundary, but the first shortwave induced Pacific Front that will waffle across the State today/tomorrow before the much stronger Arctic Front heads S...



The Arctic Boundary is currently taking shape up near MT ID and WA behind a potent Upper Air feature that will head S and E into the Intermountain West as the day wears on...

[redneckweather]

A quick side note. Once we drop into the 40's by Thursday evening, I don't see us hitting the 50 degree mark on Friday under cold air advection and solid cloud cover. If we wake up to 42 degrees Friday morning with these conditions, temperatures will not stray much at all from the low temperature we wake up to.

[wxman57]

We may see enough breaks in the clouds Friday afternoon to allow temps at IAH to reach the low 50s. Too cold for biking, though.

[wxman57]

Not much change with the 12Z GFS run. Maybe a frontal passage just a tad later Thursday afternoon. Instead of just before 3pm, now it's between 3pm-6pm. Roller coaster ride temps-wise after Thanksiving.

[weatherguy425]

I notice the Monday's front quite well towards the end of the meteogram, is it possible to run it out further or was that the max lemgth?

[Ptarmigan]

Thanksgiving Weather Statistic at KIAH from 1969 to 2009, It varies by date.

High Temperature
Mean
66.7

Median
67

Standard Deviation
11.2

Lowest High
44 (November 23, 1972)

Highest High
87 (November 22, 1973)



Low Temperature
Mean
47.7

Median
48

Standard Deviation
11.2

Lowest Low
26 (November 27, 1975)

Highest Low
65 (November 26, 1970)


Rainfall
Mean
0.07

Median
0

Standard Deviation
0.17

Lowest
0 (Numerous Times)

Highest
0.74 (November 22, 1990)

A typical day on Thanksgiving has a high of 67 and low of 48 with no rain. This Thanksgiving looks to be warmer and wetter than normal.

[Baseballdude2915]

A typical day on Thanksgiving has a high of 67 and low of 48 with no rain. This Thanksgiving looks to be warmer and wetter than normal.

Well, at least the first half of it will be LOL

[srainhoutx]

HPC:

MODEL DIAGNOSTIC DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
127 PM EST TUE NOV 23 2010

VALID NOV 23/1200 UTC THRU NOV 27/0000 UTC


...SEE NOUS42 KWNO ADMNFD FOR THE STATUS OF THE UPPER AIR
INGEST...

FINAL 12Z MODEL EVALUATION...INCLUDING THE ECMWF...

NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO IMPACT THEIR
FORECASTS.

TROUGH CROSSING THE NORTHEAST DAY 1...
THE LATEST MODELS ARE IN CLOSE AGREEMENT WITH THE TIMING OF THE
TROUGH/FRONT...AND THE TRIPLE POINT LOW FORMING EAST OF MAINE
TONIGHT.

TROUGH OVER THE WRN/CNTRL U.S...
THE GFS HAS TRENDED SLOWER WITH THE UPPER TROUGH/LOW...WHILE THE
NAM HAS TRENDED SOUTH AND FASTER. THE NAM CONTINUES TO BE AMONG
THE SLOWER SOLNS...WHILE THE GFS AND SREF MEAN ARE ON THE FAST
SIDE. PREFER THE 12Z/UKMET AND 12Z/ECMWF...WHICH SUPPORT A
COMPROMISE SPEED WITH THE UPPER LOW CENTER ACROSS THE NRN PLAINS
AND UPPER MS VALLEY....AND THE TRAILING COLD FRONT THROUGH THE TN
VALLEY AND SOUTHEAST ON DAY 3. THE 12Z/CMC INDICATES A SLOW
OUTLIER SOLN...SLOWER THAN THE NAM AND IS NOT FAVORED AT THIS
TIME.


12Z Euro (ECMWF)...

11232010 12Z Euro f72.gif

Ukmet

11232010 12zukmet850mbTSLPp06060.gif

[srainhoutx]

The Arctic Front has finally slipped S of the Canadian border...

[wxman57]

I notice the Monday's front quite well towards the end of the meteogram, is it possible to run it out further or was that the max lemgth?

I believe that you're asking if the GFS model can be plotted out beyond 192 hrs? Yes, it goes to 384 hrs. I stickied instructions as to how to create these meteograms atop the forum. One caution though is that plots beyond 192 hours are ONLY every 12 hours - at 6am and 6pm CST. The 6am plots will be somewhat close to the morning low, but the 6pm temps will be 5-7 degrees cooler than the afternoon high. Here's the plot continuing on from 12Z Dec 1 to the 384 hr point:

[srainhoutx]

Looks like HGX has decided that freezing temps may well be a bit south of where they were thinking. Also of note via Dodge City, KS is the fast nature that the front will dive S...

HGX...

CONDITIONS WILL NOT CHANGE MUCH THROUGH EARLY THANKSGIVING DAY AS
ONSHORE FLOW CONTINUES AHEAD OF THE MUCH ANTICIPATED COLD FRONTAL
PASSAGE. THE MODELS CONTINUE TO DISAGREE SLIGHTLY ON THE TIMING OF
THE FRONT...WITH THE GFS THE FASTEST AND THE NAM THE SLOWEST. WILL
KEEP CLOSE TO CURRENT FORECAST TIMING WHICH IS IN BETWEEN. THE
FRONT IS EXPECTED TO MOVE THROUGH COLLEGE STATION AND OUR NORTHERN
COUNTIES SOMETIME THURSDAY AFTERNOON AND SHOULD BE JUST TO THE
NORTH OF THE HOUSTON METRO AREA BY SUNSET...THEN OFF THE COAST
BEFORE SUNRISE ON FRIDAY. TEMPERATURES BEHIND THE FRONT WILL FALL
INTO THE UPPER 30S AND LOWER 40S...WITH SOME LIGHT SHOWERS
POSSIBLE THROUGH FRIDAY MORNING. SKIES WILL BEGIN TO CLEAR FRIDAY
AFTERNOON ALLOWING FOR GOOD COOLING OVERNIGHT. SATURDAY MORNING
WILL BE THE COLDEST MORNING WE HAVE SEEN IN QUITE A WHILE...WITH
MOST INLAND AREAS IN THE 30S. AREAS ALONG AND NORTH OF A LINE FROM
COLUMBUS TO CONROE TO LIVINGSTON WILL SEE TEMPERATURES FALL BELOW
FREEZING AT LEAST BRIEFLY.


Dodge City...

WHEN COMPARING THE NAM, RUC, GFS, GEM AND ECMWF MODELS, IT APPEARS
THE FRONT WOULD ENTER OUT CWA ABOUT 15Z WEDNESDAY IN THE
NORTHWEST, ABOUT 18Z IN GCK, 19Z IN THE DDC AND BY 22Z OR SO IN
OUR SOUTHEASTERN CWA. BUT, KNOWING THE SPEED OF COLD AIR CAN OFTEN
MOVE SOUTH THROUGH THE CWA MUCH FASTER THAN DEPICTED IN THE
MODELS, HAVE OPTED TO BRING THE FRONT THROUGH 2-4 HOURS FASTER,
AND STILL FASTER IN OUR FAR WESTERN ZONES. COLD AIR CAN PLUNGE
SOUTH THROUGH THE PLAINS WITH LITTLE OR NO RESISTANCE. SO ALSO
LOWER MAX TEMPS IN MY WESTERN ZONES WEDNESDAY, DUE TO THE EXPECTED
SOUTHERN PLUNGE OF THE COLD FRONT. WILL ALSO HAVE FALLING DAY TIME
TEMPS AFTER THE FROPA WEDNESDAY AFTERNOON. SINCE OUR WESTERN 1/3RD
OF THE CWA HAS BEEN WITHOUT PRECIP IN SO LONG, THEY ARE PRIME FOR
ANY WILDFIRES THAT MAY GENERATE. SO, WILL BE ISSUEING A FIRE
WEATHER WATCH FROM 10AM - 3PM WED, UNTIL THE FRONT PASSES THROUGH
THERE. FURTHERMORE, I CONSIDERED MENTION FLURRIES WITH THIS FAST
CHARGING COLD FRONT. BUT SINCE NO MODEL GENERATURES PRECIP AS THE
FRONT CROSSES OUR CWA, HAVE OPTED TO LEAVE ANY POPS OUT AT THIS TIME.

ALL MODELS BRING THE COLD AIR THROUGH AND PUSH IT FAR SOUTHWARD INTO
OKLAHOMA AND TEXAS WEDNESDAY NIGHT.

[Mr. T]

GFS continues to trend colder for lows saturday morning. MOS now indicates 32 degrees which would be a little bit early for our first freeze

[Mr. T]

Looks like HGX has decided that freezing temps may well be a bit south of where they were thinking. Also of note via Dodge City, KS is the fast nature that the front will dive S...

They are still going warmer than guidance for lows, though

I find it funny that HGX loves to copy and paste whatever the MOS says, unless it actually shows 32 degrees. Like if they forecasted 32 degrees for the Houston area alarms will go off or something...

[srainhoutx]

What is interesting is to see other WFO's 'bite the bullet' and go below MOS guidance, particularly in the Western areas. We'll see what the midnight crew does. Edit to add the 18Z GFS that suggests that ideal radiational cooling will be right over SE TX...

[srainhoutx]

I see some high temp records were broken or tied today...

Code: Select all

CLIMATE REPORT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
439 PM CST TUE NOV 23 2010


...................................

...THE HOUSTON INTERCONTINENTAL CLIMATE SUMMARY FOR NOVEMBER 23 2010...
VALID TODAY AS OF 0400 PM LOCAL TIME.

CLIMATE NORMAL PERIOD 1971 TO 2000
CLIMATE RECORD PERIOD 1892 TO 2010


WEATHER ITEM   OBSERVED TIME   RECORD YEAR NORMAL DEPARTURE LAST
                VALUE   (LST)  VALUE       VALUE  FROM      YEAR
                                                  NORMAL
..................................................................
TEMPERATURE (F)
 TODAY
  MAXIMUM         85R  1243 PM  85    1973  70     15       74
  MINIMUM         69    301 AM  24    1975  48     21       46
  AVERAGE         77                        59     18       60

PRECIPITATION (IN)
  TODAY            0.06          3.81 1986   0.14  -0.08     0.00
  MONTH TO DATE    2.43                      3.27  -0.84     1.17
  SINCE SEP 1      7.26                     12.10  -4.84    19.01
  SINCE JAN 1     39.40                     43.23  -3.83    41.08

Code: Select all

NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
421 PM CST TUE NOV 23 2010


...................................

...THE COLLEGE STATION CLIMATE SUMMARY FOR NOVEMBER 23 2010...
VALID TODAY AS OF 0400 PM LOCAL TIME.

CLIMATE NORMAL PERIOD 1971 TO 2000
CLIMATE RECORD PERIOD 1902 TO 2010


WEATHER ITEM   OBSERVED TIME   RECORD YEAR NORMAL DEPARTURE LAST
                VALUE   (LST)  VALUE       VALUE  FROM      YEAR
                                                  NORMAL
..................................................................
TEMPERATURE (F)
 TODAY
  MAXIMUM         86R   225 PM  84    2005  68     18       73
                                      1921
  MINIMUM         69    745 AM  23    1975  47     22       50
  AVERAGE         78                        58     20       62

PRECIPITATION (IN)
  TODAY            0.00          2.69 1940   0.10  -0.10     0.00
  MONTH TO DATE    0.73                      2.48  -1.75     2.85
  SINCE SEP 1      6.49                     10.61  -4.12    18.52
  SINCE JAN 1     26.80                     35.74  -8.94    35.60

[DPD]

When do you think the rain is going to get here?
Have some turkeys to fry and can’t do it in the rain. I am probably not the only one wondering if we can get them done early before the rain starts

Dan

[wxman57]

When do you think the rain is going to get here?
Have some turkeys to fry and can’t do it in the rain. I am probably not the only one wondering if we can get them done early before the rain starts

Dan

Get them done by noon to avoid the heavier rain. Timing isn't a certainty yet, but it looks like we may see a line of storms move through ahead of the front between 1pm-4pm. Prior to noon, maybe just a few scattered showers.

[srainhoutx]

Almost time to watch the NAM for trends...

11242010 00Z nam_500_024l.gif

11242010 00Z nam_500_048l.gif

11242010 00Z Radar Sim nam_ref_048l.gif