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

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srainhoutx
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As redneckweather photos show, it has been very cold. How cold was it and what was the historical record of the event? HGX answers the question...

CLIMATE...
THE FIRST 4 DAYS OF FEBRUARY HAVE BEEN BRUTALLY COLD. THE AVERAGE
TEMPERATURE HAS BEEN ABOUT 20 DEGREES COLDER THAN NORMAL. THE LAST
TIME HOUSTON RECEIVED 5 CONSECUTIVE DAYS WITH MIN TEMPS EQUAL TO
OR BELOW 28 DEGREES WAS FEB 1989.
THIS IS THE 4TH COLDEST START TO
FEB FOR THE CITY OF HOUSTON.
ONLY FEB 1-4 IN 1985...1951 AND 1996
WERE COLDER
.
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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unome
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HGX issued a Public Information Statement with stats: http://www.srh.noaa.gov/productview.php?pil=HGXPNSHGX

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
648 AM CST SAT FEB 5 2011

...FEBRUARY BEGINS ON A FRIGID NOTE...

UNLESS YOU LIVE IN A CAVE OR AN IGLOO...YOU ARE PROBABLY AWARE
THAT THE FIRST FOUR DAYS OF FEBRUARY HAVE BEEN VERY COLD. THE
AVERAGE TEMPERATURE FOR THE PRIMARY CLIMATE SITES OF HOUSTON...
HOUSTON HOBBY AIRPORT...COLLEGE STATION AND GALVESTON HAVE ALL
AVERAGED ALMOST 20 DEGREES COLDER THAN THE 30 YEAR CLIMATE
NORMALS. HOUSTON AND COLLEGE STATION HAVE RECORDED FIVE
CONSECUTIVE MORNINGS WITH LOW TEMPERATURES IN THE 20S. THIS HAS
NOT HAPPENED IN FEBRUARY SINCE 1989. WIND CHILL VALUES HAVE ALSO
BEEN BRUTALLY COLD WITH VALUES DIPPING INTO THE SINGLE DIGITS A
FEW DAYS AGO.

BELOW IS A TABLE WITH THE COLDEST AVERAGE HIGH...LOW AND AVERAGE DAILY
TEMPERATURES FOR FEBRUARY (THROUGH THE 4TH) FOR THE FOUR PRIMARY
CLIMATE SITES:

HOUSTON

AVG HIGH AVG LOW AVG DAILY

36.2 1985 22.2 1951 30.8 1985
38.5 1996 24.0 2011 32.1 1951
42.0 1951 25.2 1985 33.0 1996
42.8 1905 27.5 1996 33.8 2011
43.5 2011 29.5 1917 39.2 1916


HOUSTON HOBBY

AVG HIGH AVG LOW AVG DAILY

36.0 1996 20.2 1951 30.9 1951
39.0 1985 27.0 2011 33.1 1996
41.5 1951 28.2 1996 34.2 1985
44.2 2011 29.5 1985 35.6 2011
47.0 1978 32.0 1966 42.0 1980

COLLEGE STATION

AVG HIGH AVG LOW AVG DAILY

32.5 1985 15.8 1951 27.0 1985
35.0 1996 21.2 2011 29.4 1996
42.0 2011 21.8 1985 29.5 1951
42.8 1951 23.8 1996 31.6 2011
42.8 1905 26.0 1918 37.3 1916

GALVESTON

AVG HIGH AVG LOW AVG DAILY

38.0 1985 26.8 1951 34.0 1985
39.2 1996 28.5 2011 34.2 1951
41.8 1951 30.0 1985 35.0 1996
42.0 2011 30.8 1996 35.2 2011
45.8 1978 34.2 1917 42.2 1905

EACH OF THE PRIMARY CLIMATE SITES HAD THEIR 2ND COLDEST AVERAGE
LOW TEMPERATURES FOR THE FIRST FOUR DAYS OF THE MONTH. ALTHOUGH
TEMPERATURES REBOUND A BIT DURING THE FIRST HALF OF NEXT WEEK...
IT TURNS COLDER FOR THE SECOND HALF WITH LOW TEMPERATURES BACK IN
THE 20S. DON`T LET THE COLD START TO THE MONTH FOOL YOU. BACK IN
1996...THE FIRST FOUR DAYS OF FEBRUARY WERE COLD BUT AN EXPANSIVE
UPPER RIDGE BUILT OVER TEXAS ON THE 21ST...22ND AND 23RD WITH
COLLEGE STATION RECORDING A RECORD HIGH TEMPERATURE OF 99 DEGREES
ON THE 21ST AND HOUSTON RECORDING A RECORD HIGH OF 90 ON THE 22ND.
AHHHH WEATHER...YOU JUST NEVER KNOW.

$$
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22ND AND 23RD WITH
COLLEGE STATION RECORDING A RECORD HIGH TEMPERATURE OF 99 DEGREES
ON THE 21ST AND HOUSTON RECORDING A RECORD HIGH OF 90 ON THE 22ND.
AHHHH WEATHER...YOU JUST NEVER KNOW.


After next week's arctic air, I'm betting the blow torch will be turned on. Not to this extreme but I expect a pretty good rebound in temps the following week and thereafter...........I HOPE!!! :D
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srainhoutx
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Finally, I have gone above freezing at my location. Nearly 88 hours of below freezing temps have ended.
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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jeff
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tireman4 wrote:This is from Air Force Met at Storm2k. The rundown on our ice storm/not snow storm science I have heard. Meteorology 101.


I've got lots of lessons learned for this past event. I am putting a bust review together and will be glad to share when its completed.

I already know where the forecast when wrong...and looking via hind site...it was very obvious that SE TX would see a freezing rain event...even with the available guidance.

BASICALLY: I saw the negatives...and dis-regarded them because the models themselves were putting down snow. The GFS/NAM/Euro/GEM were all putting out snow depths of varying degrees. I falsely assumed (and that is because I don't know how the models do the calculating) that the "snow" parameters were built into the models and that THEY would QC themselves...and if certain parameters were not met...then they wouldn't put a 1" snow depth over an area. I assumed the model would know the critical thicknesses. That's why when I noticed that critical temps and critical thicknesses were not being met...I assumed I wasn't reading something right.

Well...I was reading it right and the model was ignoring it. That makes it even more frustrating. It's one thing to blow a forecast because you didn't see something. Its another thing to blow it when you know what the rules of thumb are saying...and you ignore them because the model said something different. THAT'S being a model reader and I've always hated it when forecasters do that (since so many today have lost the true skills of forecasting and instead read the models).

Another critical value that I saw lacking...spoke about it here and talked at length to Jeff about it on Tuesday/Wednesday (and with several other mets as well) was the -8C critical temp rule of thumb. That rule says "If you have a melting layer, then the temp of the cold layer below MUST be -8C somewhere in the column. If not, freezing rain is the result."

None of the models showed that -8C mark at anything below 600MB...and above 500-600mb...it was dry...so no snow being made there. THEN...even when it was moist...the melting layer at 850-700 was thick enough to melt the snow above it...and there was no -8C below it...so it fell as sleet and freezing rain. If the snow melts...you must reach -8C for it to re-freeze into snow. If not...it remains super-cooled and liquid until it reaches the ground...or it turns to sleet.

So yes...a very frustrating forecast...especially given that temps were never below -8C...and the critical thicknesses of 1000-500, 850-500, and 700-500 (the last two are VERY important if you have a warm layer...which we did) were all above the threshold. And in this instance...the last 2 were spot on if you took a blend of them. ALSO...using the partial thickness table...the Rules state...if you have a 1000-850 thickness of 129-131 DM...and a 850-700 thickness of >154 DM, you should expect "Freezing rain, with sleet near 154DM on the 850-700."

At 06z, Houston had thicknesses of 129 and 155. So...freezing rain mixed with sleet...
At 12Z...127 and 154. That rules states: "Freezing rain/freezing drizzle and sleet" with weak upper level forcing and little/no CAA at the surface.

I will have more in my bust review...but the best thickness values for this event (due to the warm layer) was the 850-500 thickness. It was almost spot on...
The interesting thing is that at 18Z on Thursday CLL (TAMU) did launch a sounding and the NWS reported it was a snow profile (but with dry layers) I did not see the sounding so I do not know. The real kicker is that KCLL started as ZR and not IP or SN Thursday evening which is really when I knew we were in trouble for SN.

Also most of the early afternoon stuff on Thursday was IP even along the coast and inland with dbz around 20-25...it was not ZR, There was for sure strong WAA in the 850-700mb layer Thursday afternoon/evening that really modified the thermo profile which was extremely clear on the 00Z KLCH sounding that evening.

What is surprising if that even though the proper "rules" were not met, no one really saw a ZR event instead of SN including all the WFO's. The only one that kept harping on ZR was CRP which thought ZR was the better choice then a change to IP and SN. Everyone had various degrees of accumulations of SN and IP with ZR held right along the coast. I am not sure anyone would have gotten that WAA right even if HOU would have had a sounding...I do not think it was there the day before or Thursday morning and then at 00Z it would have appeared....well you still would have forecasted the same P-type up until the event was starting and then done the 180..again numerous IP was reported Thursday AM/midday on the coast so there was some serious modification above the surface Thursday afternoon and you could almost see that in the echo movement on the radar Thursday evening as the light ZR spread/moved NNW over the area (WAA)

Luckily from an impacts stand point the correct decisions were made..what would have really been bad is if everything shut down and it did not precipitate at all. We really got an un-forecasted worse case event(ZR with glazing), but luckily we were prepared for snow...you really do the same thing for both. A good attempt I suppose!
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jeff wrote:
tireman4 wrote:This is from Air Force Met at Storm2k. The rundown on our ice storm/not snow storm science I have heard. Meteorology 101.


I've got lots of lessons learned for this past event. I am putting a bust review together and will be glad to share when its completed.

I already know where the forecast when wrong...and looking via hind site...it was very obvious that SE TX would see a freezing rain event...even with the available guidance.

BASICALLY: I saw the negatives...and dis-regarded them because the models themselves were putting down snow. The GFS/NAM/Euro/GEM were all putting out snow depths of varying degrees. I falsely assumed (and that is because I don't know how the models do the calculating) that the "snow" parameters were built into the models and that THEY would QC themselves...and if certain parameters were not met...then they wouldn't put a 1" snow depth over an area. I assumed the model would know the critical thicknesses. That's why when I noticed that critical temps and critical thicknesses were not being met...I assumed I wasn't reading something right.

Well...I was reading it right and the model was ignoring it. That makes it even more frustrating. It's one thing to blow a forecast because you didn't see something. Its another thing to blow it when you know what the rules of thumb are saying...and you ignore them because the model said something different. THAT'S being a model reader and I've always hated it when forecasters do that (since so many today have lost the true skills of forecasting and instead read the models).

Another critical value that I saw lacking...spoke about it here and talked at length to Jeff about it on Tuesday/Wednesday (and with several other mets as well) was the -8C critical temp rule of thumb. That rule says "If you have a melting layer, then the temp of the cold layer below MUST be -8C somewhere in the column. If not, freezing rain is the result."

None of the models showed that -8C mark at anything below 600MB...and above 500-600mb...it was dry...so no snow being made there. THEN...even when it was moist...the melting layer at 850-700 was thick enough to melt the snow above it...and there was no -8C below it...so it fell as sleet and freezing rain. If the snow melts...you must reach -8C for it to re-freeze into snow. If not...it remains super-cooled and liquid until it reaches the ground...or it turns to sleet.

So yes...a very frustrating forecast...especially given that temps were never below -8C...and the critical thicknesses of 1000-500, 850-500, and 700-500 (the last two are VERY important if you have a warm layer...which we did) were all above the threshold. And in this instance...the last 2 were spot on if you took a blend of them. ALSO...using the partial thickness table...the Rules state...if you have a 1000-850 thickness of 129-131 DM...and a 850-700 thickness of >154 DM, you should expect "Freezing rain, with sleet near 154DM on the 850-700."

At 06z, Houston had thicknesses of 129 and 155. So...freezing rain mixed with sleet...
At 12Z...127 and 154. That rules states: "Freezing rain/freezing drizzle and sleet" with weak upper level forcing and little/no CAA at the surface.

I will have more in my bust review...but the best thickness values for this event (due to the warm layer) was the 850-500 thickness. It was almost spot on...
The interesting thing is that at 18Z on Thursday CLL (TAMU) did launch a sounding and the NWS reported it was a snow profile (but with dry layers) I did not see the sounding so I do not know. The real kicker is that KCLL started as ZR and not IP or SN Thursday evening which is really when I knew we were in trouble for SN.

Also most of the early afternoon stuff on Thursday was IP even along the coast and inland with dbz around 20-25...it was not ZR, There was for sure strong WAA in the 850-700mb layer Thursday afternoon/evening that really modified the thermo profile which was extremely clear on the 00Z KLCH sounding that evening.

What is surprising if that even though the proper "rules" were not met, no one really saw a ZR event instead of SN including all the WFO's. The only one that kept harping on ZR was CRP which thought ZR was the better choice then a change to IP and SN. Everyone had various degrees of accumulations of SN and IP with ZR held right along the coast. I am not sure anyone would have gotten that WAA right even if HOU would have had a sounding...I do not think it was there the day before or Thursday morning and then at 00Z it would have appeared....well you still would have forecasted the same P-type up until the event was starting and then done the 180..again numerous IP was reported Thursday AM/midday on the coast so there was some serious modification above the surface Thursday afternoon and you could almost see that in the echo movement on the radar Thursday evening as the light ZR spread/moved NNW over the area (WAA)

Luckily from an impacts stand point the correct decisions were made..what would have really been bad is if everything shut down and it did not precipitate at all. We really got an un-forecasted worse case event(ZR with glazing), but luckily we were prepared for snow...you really do the same thing for both. A good attempt I suppose!
Great discussion!!! I, to say the least, am a rank amateur, reading this and some discussions I have had with other mets makes me realize what I did when looking at(relying on)the models. Hopefully I will learn from that. It is too bad that the funding is not present for having the proper amount of soundings available, especially along the Gulf Coast and for that matter, all over Texas. Perhaps we need to be pressuring our congresspersons to properly fund and staff our NWS offices so there are enough soundings available to properly forecast these events.
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The other thing is that no one got the correct location of the snow (along I-35) and a good blow for Dallas. Everyone was on board with not enough moisture that far inland. The whole deal was a forecasting disaster from P-type to accumulations to locations. It was almost all wrong....even though the WSW verified for the wrong reasons!

I have learned one thing...because forecasting is as much a social science also, is a blown forecast is much easier for the public to take if it is bodes well for them. For example if we would have forecasted 1/4 an inch of freezing rain and ice and got 4 inches of snow instead...we would really not be having this discussion right now. Down here everyone wants snow...so if you forecast it you better be darn sure it is going to happen. Did you hear anyone complain that the forecasters did not predict a foot of snow in Dec 04, no instead it was termed a Christmas miracle...never mind the forecasts were for 1-2 inches and a Winter Storm Warning was not issued under the event was underway.

Be ready for the backlash when we do not deliver want the public wants...regardless of the science...I will always remember that from this point forward. Since when do meteorologist take orders for the weather and then produce it...but that is almost what it is becoming...they do not want freezing rain they want snow and only snow! Folks seem to be OK getting surprised extreme events with little forecasting for them, while they are much the opposite in getting strong forecast for extreme events and nothing happening...it holds for anything in weather.
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jeff wrote:The other thing is that no one got the correct location of the snow (along I-35) and a good blow for Dallas. Everyone was on board with not enough moisture that far inland. The whole deal was a forecasting disaster from P-type to accumulations to locations. It was almost all wrong....even though the WSW verified for the wrong reasons!

I have learned one thing...because forecasting is as much a social science also, is a blown forecast is much easier for the public to take if it is bodes well for them. For example if we would have forecasted 1/4 an inch of freezing rain and ice and got 4 inches of snow instead...we would really not be having this discussion right now. Down here everyone wants snow...so if you forecast it you better be darn sure it is going to happen. Did you hear anyone complain that the forecasters did not predict a foot of snow in Dec 04, no instead it was termed a Christmas miracle...never mind the forecasts were for 1-2 inches and a Winter Storm Warning was not issued under the event was underway.

Be ready for the backlash when we do not deliver want the public wants...regardless of the science...I will always remember that from this point forward. Since when do meteorologist take orders for the weather and then produce it...but that is almost what it is becoming...they do not want freezing rain they want snow and only snow! Folks seem to be OK getting surprised extreme events with little forecasting for them, while they are much the opposite in getting strong forecast for extreme events and nothing happening...it holds for anything in weather.
Exactly! You nailed it right on. Weather is like history, politics, and economics.
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Ptarmigan wrote:
jeff wrote:The other thing is that no one got the correct location of the snow (along I-35) and a good blow for Dallas. Everyone was on board with not enough moisture that far inland. The whole deal was a forecasting disaster from P-type to accumulations to locations. It was almost all wrong....even though the WSW verified for the wrong reasons!

I have learned one thing...because forecasting is as much a social science also, is a blown forecast is much easier for the public to take if it is bodes well for them. For example if we would have forecasted 1/4 an inch of freezing rain and ice and got 4 inches of snow instead...we would really not be having this discussion right now. Down here everyone wants snow...so if you forecast it you better be darn sure it is going to happen. Did you hear anyone complain that the forecasters did not predict a foot of snow in Dec 04, no instead it was termed a Christmas miracle...never mind the forecasts were for 1-2 inches and a Winter Storm Warning was not issued under the event was underway.

Be ready for the backlash when we do not deliver want the public wants...regardless of the science...I will always remember that from this point forward. Since when do meteorologist take orders for the weather and then produce it...but that is almost what it is becoming...they do not want freezing rain they want snow and only snow! Folks seem to be OK getting surprised extreme events with little forecasting for them, while they are much the opposite in getting strong forecast for extreme events and nothing happening...it holds for anything in weather.
Exactly! You nailed it right on. Weather is like history, politics, and economics.

Wow this should be quoted and made into a new topic then pinned so everyone could read it.
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