Upcoming cold for the South (Models, Maps, Discussions)

[Tyler]

Aren't "light" or "hard" freezes determined by the number of hours an area remains below 32, and not based solely on the actual air temp?

Yes, I would think if SE TX hit the mid 20's, we'd be below freezing for maybe 5 or 6 hours. Thats a pretty good freeze.

[jasons2k]

Here's the first cut from this PM:

From Midland/Odessa:
A COLD FRONT SHOULD BRIDGE INTO THE AREA WEDNESDAY WITH SURFACE WIND BECOMING EASTERLY AS CENTER OF RIDGE SLIDES SOUTH OF THE RED RIVER. SOUTH WIND WILL RETURN LATE THURSDAY HELPING KEEP LOWS UP THURSDAY NIGHT. A WEEK FRONT ON FRIDAY WILL SHIFT THE WIND BACK AROUND TO THE NORTH WITH LITTLE COOLING EXPECTED. OVERALL TEMPERATURES LOOK MILD AND NEAR NORMAL THROUGH THE WEEKEND. A STRONGER FRONT IS EXPECTED MONDAY THAT WILL KNOCK HIGHS POSSIBLY DOWN INTO THE 40S BY NEXT TUESDAY.

From Brownsville:
THE MAIN THRUST OF UPPER LEVEL ENERGY WILL COME THROUGH FRIDAY NIGHT ALONG WITH A COLD FRONT. SHOWER ACTIVITY WILL INCREASE AT THAT TIME. MIDLEVEL ENERGY AND SOUTHWEST WINDS ALOFT WILL REMAIN IN THE REGION OVER THE WEEKEND...SETTING UP WEAK OVERRUNNING CONDITIONS WITH NORTHWEST SURFACE WINDS AT THE SFC BEHIND THE FRONT. ISENTROPIC LIFT MAY INCREASE FURTHER EARLY NEXT WEEK WITH EAST FLOW AT THE SFC AND WEST WINDS ALOFT.

Corpus:
THE TIMING OF THE MODIFIED ARCTIC COLD
FNT IS EXPECTED TO BE FRI NIGHT. THE MAIN DIFFERENCES NOTED IN THE MEDIUM RANGE GUIDANCE ARE THE STRENGTH OF THE ANTICYCLONE BEHIND THE FNT AND HOW FAR TO PUSH THE COLD AIR. THE GFS MAINTAINS THE WEAKEST ANTICYCLONE AND SUBSEQUENTLY KEEPS THE BRUNT OF THE REALLY COLD AIR TO OUR NORTH. THE ECMWF/CANADIAN AND NOGAPS SOLNS ALL POINT TO A MUCH STRONGER ARCTIC HIGH PRESSURE AREA (1040+ MB) BEHIND THIS FNT AND A SUBSEQUENT DEEPER PENETRATION OF COLDER AIR ACROSS SOUTH TX. GIVEN THAT THE GFS IS THE OUTLIER AND ITS POOR PERFORMANCE WITH SHALLOW COLD AIRMASSES THIS SEASON...I AM LEANING TWDS THE MUCH COLDER SOLNS OF THE ECMWF/CANADIAN/NOGAPS. THIS WL BE MOST NOTICEABLE FOR OVERNIGHT LOWS ON SAT WHERE WIDESPREAD FREEZING TEMPS ARE EXPECTED. A GRADUAL MODIFICATION OF THE AIRMASS IS EXPECTED EARLY NEXT WEEK AS WINDS ONCE AGAIN VEER IN RESPONSE TO ANOTHER S/WV DIVING SEWD.

[Tyler]

Corpus Christi NWS AFD:

000
FXUS64 KCRP 072043
AFDCRP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CORPUS CHRISTI TX
243 PM CST TUE FEB 7 2006


.LONG-TERM (THURSDAY THROUGH TUESDAY)...THE MAIN ISSUES FOR THIS
FCST PD WL BE WITH RAIN CHANCES ON FRI AND WITH TEMPS BEHIND THE
MODIFIED ARCTIC FNT EXPECTED FRI NIGHT. RIDGING AT ALL LVLS WL
INITIALLY MAINTAIN THE DRY AIRMASS ACROSS SOUTH TX ON THU. THE UPR
LVL RDG AXIS IS EXPECTED TO FLATTEN OUT THU NIGHT AND FRI DUE TO AN
APPROACHING SRN STREAM S/WV OVER THE DESERT SOUTHWEST/NRN MEXICO RGN
AND ALSO DUE TO AN INCREASING INFLUENCE FROM A POWERFUL NRN STREAM
JET. THE NET RESULT WL BE TO INCREASE LIFT ISENTROPICALLY THROUGH
FRI NIGHT. SOM WK DYNAMICS IS ALSO EXPECTED FROM THE SHEARING S/WV
TO OUR WEST. THE GFS IS ONCE AGAIN OVERDONE WITH ITS MOISTURE FIELDS
WHILE THE ETA IS A BIT TOO DRY. WL TAKE A COMPROMISE WITH THESE TWO
SOLNS AND GO WITH SLIGHT CHC TO CHC POPS BEGINNING EARLY FRI MORNING
THROUGH EARLY SAT MORNING. THE TIMING OF THE MODIFIED ARCTIC COLD
FNT IS EXPECTED TO BE FRI NIGHT. THE MAIN DIFFERENCES NOTED IN THE
MEDIUM RANGE GUIDANCE ARE THE STRENGTH OF THE ANTICYCLONE BEHIND THE
FNT AND HOW FAR TO PUSH THE COLD AIR. THE GFS MAINTAINS THE WEAKEST
ANTICYCLONE AND SUBSEQUENTLY KEEPS THE BRUNT OF THE REALLY COLD AIR
TO OUR NORTH. THE ECMWF/CANADIAN AND NOGAPS SOLNS ALL POINT TO A
MUCH STRONGER ARCTIC HIGH PRESSURE AREA (1040+ MB) BEHIND THIS FNT
AND A SUBSEQUENT DEEPER PENETRATION OF COLDER AIR ACROSS SOUTH TX.
GIVEN THAT THE GFS IS THE OUTLIER AND ITS POOR PERFORMANCE WITH
SHALLOW COLD AIRMASSES THIS SEASON...I AM LEANING TWDS THE MUCH
COLDER SOLNS OF THE ECMWF/CANADIAN/NOGAPS. THIS WL BE MOST
NOTICEABLE FOR OVERNIGHT LOWS ON SAT WHERE WIDESPREAD FREEZING TEMPS
ARE EXPECTED. A GRADUAL MODIFICATION OF THE AIRMASS IS EXPECTED
EARLY NEXT WEEK AS WINDS ONCE AGAIN VEER IN RESPONSE TO ANOTHER
S/WV DIVING SEWD. WL GO WITH RAIN CHCS WITH THIS SECOND SYSTEM BY
TUE.

[Tyler]

Corpus Christi going against the GFS, as its the ONLY model so weak. As they stated, Euro, NOGAPS and the Canadian are all in agreement with each other.

[gboudx]

From Dodge City on the extended:

BEYOND THIS TIME, THE MODELS ARE STILL THROWING OUT SOME HINTS AT A
RETROGRESSION OF THE UPPER LEVEL RIDGE OFF THE WEST COAST WHICH
WOULD HELP LOWER HEIGHTS OVER THE WESTERN CONUS INTO WESTERN CANADA.
THE GFS ENSEMBLES ARE HEADING IN THIS DIRECTION AS WELL. WHAT IS
CURIOUS IS THAT THE ECMWF AND CANADIAN ARE KEEPING THE TROUGH
FARTHER NORTH WITH FAIRLY ZONAL FLOW ACROSS THE NORTHERN CONUS WHICH
WOULD NOT BODE WELL FOR SOUTHWARD TRANSPORT OF COLDER AIR. THIS
WILL HAVE TO BE WATCHED TO SEE IF ANY CONSOLIDATION IN THE MODEL
SOLUTIONS OCCUR BUT FOR NOW WILL KEEP THE 8 TO 10 DAY PERIOD NEAR
NORMAL AND BELOW NORMAL FOR TEMPERATURES AND PRECIPITATION,
RESPECTIVELY.

[Extremeweatherguy]

I have a few things to remind people of. First off...those records that some keep referring to, are the records of the more modern era. The NWS does not show the records for before 1927. What does that do? LEAVE OUT MOST OF FEBRUARY'S GREATEST COLD SNAPS! For example, during the 1899 cold snap...Houston hit 6 degrees on Feb. 12th and 13th...so if you look at it in those perspectives, then no; this cold snap should not see overall record breaking lows, but it may get cold enough to break records since 1927. Also, another point I want to make is that...DO NOT TRUST THE NWS YET!!! Yes, I realize they are warm...but remember the early December cold snap? 4 days out they were forecasting lower 50s for highs and middle 30s for lows...and we ended up seeing middle 30s for highs and upper 20s for lows....BIG FORECAST BUST! Also...the GFS (as Tyler has said) is not the all knowing model. We need to base our predictions on ALL the models...not just one.

[Extremeweatherguy]

Here's the first cut from this PM:

From Midland/Odessa:
A COLD FRONT SHOULD BRIDGE INTO THE AREA WEDNESDAY WITH SURFACE WIND BECOMING EASTERLY AS CENTER OF RIDGE SLIDES SOUTH OF THE RED RIVER. SOUTH WIND WILL RETURN LATE THURSDAY HELPING KEEP LOWS UP THURSDAY NIGHT. A WEEK FRONT ON FRIDAY WILL SHIFT THE WIND BACK AROUND TO THE NORTH WITH LITTLE COOLING EXPECTED. OVERALL TEMPERATURES LOOK MILD AND NEAR NORMAL THROUGH THE WEEKEND. A STRONGER FRONT IS EXPECTED MONDAY THAT WILL KNOCK HIGHS POSSIBLY DOWN INTO THE 40S BY NEXT TUESDAY.

From Brownsville:
THE MAIN THRUST OF UPPER LEVEL ENERGY WILL COME THROUGH FRIDAY NIGHT ALONG WITH A COLD FRONT. SHOWER ACTIVITY WILL INCREASE AT THAT TIME. MIDLEVEL ENERGY AND SOUTHWEST WINDS ALOFT WILL REMAIN IN THE REGION OVER THE WEEKEND...SETTING UP WEAK OVERRUNNING CONDITIONS WITH NORTHWEST SURFACE WINDS AT THE SFC BEHIND THE FRONT. ISENTROPIC LIFT MAY INCREASE FURTHER EARLY NEXT WEEK WITH EAST FLOW AT THE SFC AND WEST WINDS ALOFT.

Corpus:
THE TIMING OF THE MODIFIED ARCTIC COLD
FNT IS EXPECTED TO BE FRI NIGHT. THE MAIN DIFFERENCES NOTED IN THE MEDIUM RANGE GUIDANCE ARE THE STRENGTH OF THE ANTICYCLONE BEHIND THE FNT AND HOW FAR TO PUSH THE COLD AIR. THE GFS MAINTAINS THE WEAKEST ANTICYCLONE AND SUBSEQUENTLY KEEPS THE BRUNT OF THE REALLY COLD AIR TO OUR NORTH. THE ECMWF/CANADIAN AND NOGAPS SOLNS ALL POINT TO A MUCH STRONGER ARCTIC HIGH PRESSURE AREA (1040+ MB) BEHIND THIS FNT AND A SUBSEQUENT DEEPER PENETRATION OF COLDER AIR ACROSS SOUTH TX. GIVEN THAT THE GFS IS THE OUTLIER AND ITS POOR PERFORMANCE WITH SHALLOW COLD AIRMASSES THIS SEASON...I AM LEANING TWDS THE MUCH COLDER SOLNS OF THE ECMWF/CANADIAN/NOGAPS. THIS WL BE MOST NOTICEABLE FOR OVERNIGHT LOWS ON SAT WHERE WIDESPREAD FREEZING TEMPS ARE EXPECTED. A GRADUAL MODIFICATION OF THE AIRMASS IS EXPECTED EARLY NEXT WEEK AS WINDS ONCE AGAIN VEER IN RESPONSE TO ANOTHER S/WV DIVING SEWD.

I wouldn't call Brownsville or Midland good sources for what Houston should expect. First off...I think that this cold snap will probably not focus it's coldest air south to Brownsville...and second Midland is very far west and will be much less impacted by this front.

[Tyler]

I have a few things to remind people of. First off...those records that some keep referring to, are the records of the more modern era. The NWS does not show the records for before 1927. What does that do? LEAVE OUT MOST OF FEBRUARY'S GREATEST COLD SNAPS! For example, during the 1899 cold snap...Houston hit 6 degrees on Feb. 12th and 13th...so if you look at it in those perspectives, then no; this cold snap should not see overall record breaking lows, but it may get cold enough to break records since 1927. Also, another point I want to make is that...DO NOT TRUST THE NWS YET!!! Yes, I realize they are warm...but remember the early December cold snap? 4 days out they were forecasting lower 50s for highs and middle 30s for lows...and we ended up seeing middle 30s for highs and upper 20s for lows....BIG FORECAST BUST! Also...the GFS (as Tyler has said) is not the all knowing model. We need to base our predictions on ALL the models...not just one.

Alright, Extreme is back! Finally someone is backing me up here.

[Tyler]

I wouldn't call Brownsville or Midland good sources for what Houston should expect. First off...I think that this cold snap will probably not focus it's coldest air south to Brownsville...and second Midland is very far west and will be much less impacted by this front.

Corpus AFD is excellent. They realize how much the GFS is BS this weekend. When you have all global models against the GFS, its pretty easy to see which one is right.

[Extremeweatherguy]

Here are the latest model ideas on the strength of the high...the stronger the high; the colder we get:

NAM = at least 1044mb
GFS = around 1031mb (HA! WRONG!)
EURO = 1048mb
UKMET = at least 1044mb
ETA = at least 1044mb

**I mean come on! It is obvious who the outlier is...**

[gboudx]

Alright, Extreme is back! Finally someone is backing me up here.

I appreciate you posting all the info you do. I just don't have the meteorological experience to refute or validate your points. Just keep doing what you're doing. We'll see how credible your points are after this weekend.

Just joking with you on that last part.

[Extremeweatherguy]

I have a few things to remind people of. First off...those records that some keep referring to, are the records of the more modern era. The NWS does not show the records for before 1927. What does that do? LEAVE OUT MOST OF FEBRUARY'S GREATEST COLD SNAPS! For example, during the 1899 cold snap...Houston hit 6 degrees on Feb. 12th and 13th...so if you look at it in those perspectives, then no; this cold snap should not see overall record breaking lows, but it may get cold enough to break records since 1927. Also, another point I want to make is that...DO NOT TRUST THE NWS YET!!! Yes, I realize they are warm...but remember the early December cold snap? 4 days out they were forecasting lower 50s for highs and middle 30s for lows...and we ended up seeing middle 30s for highs and upper 20s for lows....BIG FORECAST BUST! Also...the GFS (as Tyler has said) is not the all knowing model. We need to base our predictions on ALL the models...not just one.

Alright, Extreme is back! Finally someone is backing me up here.

lol. looked like you needed some help.

[Tyler]

Right Extreme! Actually the GFS has the high at only 1033 at one point, while at the SAME time, the Euro has it as a 1047 over Montana (after it was a 1048 in Canada).

Its just crazy what the GFS is spitting at us for this weekend. I'm confused as to what the heck the GFS is thinking...

Needless to say, tonight's 0z runs are CRITICAL.

[Tyler]

Alright, Extreme is back! Finally someone is backing me up here.

I appreciate you posting all the info you do. I just don't have the meteorological experience to refute or validate your points. Just keep doing what you're doing. We'll see how credible your points are after this weekend.

Just joking with you on that last part.

LOL I'd really love it if we did have some Pro input here. I think AFM and jeff are really busy at the moment, though.

[Tyler]

18z NAM. Sticks with 1044MB high! GFS, when will you surrender!?

http://www.nco.ncep.noaa.gov/pmb/nwprod ... /fpc.shtml

[Extremeweatherguy]

18z NAM. Sticks with 1044MB high! GFS, when will you surrender!?

http://www.nco.ncep.noaa.gov/pmb/nwprod ... /fpc.shtml

exactly! When will it pick up on the idea that it WILL NOT be a 1033mb high...but rather a 1040-1050mb high? The GFS seemed like it was doing the best too just a few days ago. What happened? Where is that -9C 850mb temp. the GFS had predicted just a few days ago?

[Extremeweatherguy]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
306 PM CST TUE FEB 7 2006

.DISCUSSION...
THE 500 MB PATTERN WITH A RIDGE OVER THE PACIFIC COAST AND LOW
OVER EASTERN CANADA WILL KEEP SE TX UNDER A NORTHWESTERLY FLOW
THROUGH THE WEEKEND AND HELP TO PUSH A COUPLE OF FRONTS THROUGH
THE AREA. THE GFS SHOWS A PATTERN CHANGE EARLY NEXT WEEK AS THE
MODEL DEVELOPS A TROUGH OUT WEST.

THE TEMPERATURES ARE THE MAIN CHALLENGE FOR THE NEXT FEW DAYS...
THEN POPS BECOME A CONCERN OVER THE WEEKEND. THE MODELS DIFFER A
BIT ON THE TIMING AND STRENGTH OF THE SYSTEM ON FRIDAY WITH THE
GFS MORE AGGRESSIVE. GIVEN THAT UNCERTAINTY...WILL STAY WITH THE
CURRENT POPS.

THE SURFACE HIGH WILL BRING CLEAR SKIES AND LIGHT WINDS TONIGHT
WHICH WILL ALLOW THE TEMPERATURES TO FALL INTO THE 30S OVER THE
INLAND AREAS NORTH OF I-10. SOME LOCATIONS NORTHEAST OF METRO
HOUSTON MAY DROP TO NEAR FREEZING. WEDNESDAY WILL BE A BIT WARMER
AHEAD OF THE NEXT FRONT. GIVEN THE UNCERTAINTY OF THE MODEL DATA
AFTER FRIDAY...DID NOT MAKE ANY LARGE CHANGES TO THE CURRENT
TEMPERATURE FORECAST.

The Houston NWS looks very confused about the weekend and they seemed to have stayed away from the topic about how cold it will be. Seems to me that they are waiting on further model runs...but at least they have not warmed the forecast any.

[Tyler]

Yes, the Houston forecast was not changed at all.

Is it me, or did the 18Z GFS initialize the high pressure areas around the US too weak. Call me crazy, but maybe this has been the problem all along. The NAM looked okay, but the GFS initialization looked off to me, as far as surface pressures go.

[Tyler]

Well anyway, 18z GFS already stronger with the high pressure centers at 48 hours than the 12z GFS

[gboudx]

Pertinent part of the DFW AFD.

MEDIUM RANGE MODEL GUIDANCE FROM THE ECMWF/CMC/UKMET SUITES...AS
WELL AS FROM THE GFSLR...CONTINUE TO SUGGEST AN AMPLIFICATION OF
MID/UPPER LEVEL RIDGING ALONG THE WESTERN COAST OF CANADA BY LATE
WEEK...WITH VERY COLD AIR PROGGED TO SLIDE SOUTHWARD DOWN THE LEE OF
THE ROCKIES AS A RESULT. SOME DIFFERENCES EXIST REGARDING THE
STRENGTH OF THE COLD AIRMASS...WITH THE CMC GUIDANCE THE COLDEST
AND THE GFSLR GUIDANCE THE WARMEST. THE TRUE STRENGTH OF THE
AIRMASS WILL LIKELY BE SOMEWHERE BETWEEN THE TWO EXTREMES...WITH A
NOTICEABLE COOLING TREND EXPECTED BY LATE FRIDAY. HOWEVER...
TEMPERATURES WILL NOT BE NEARLY AS COLD AS THOSE EXPERIENCED WITH
THE OUTBREAK OF ARCTIC AIR LAST DECEMBER.