November: Warm and Dry To End The Month

[Belmer]

So 9 days out from now is Thanksgiving Day, current forecast is for mid to upper 70s for highs. Lows in the upper 50s to lower 60s. As of now, no rain in the forecast, just mild.
All I can say... YUCK!!!

[mckinne63]

Loving the cooler temps, but we really need some rain. Can't we have the best of both worlds? Cooler temps AND rain?

[srainhoutx]

A zonal flow pattern is in the works for the remainder of the week. Seasonal temps with dry weather should continue into the weekend before a return flow becomes established and moisture slowly builds ahead of another Western trough. The GFS ensembles are in agreement that the best chance for rain will occur next Tuesday into Wednesday as an upper level disturbance traverses across the Lone Star State/Southern Plains. At this time it appears the rain chances will decrease just in time for Thanksgiving as another East Coast storm threatens the Mid Atlantic.

SPC:

DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0348 AM CST WED NOV 14 2012

VALID 171200Z - 221200Z

...DISCUSSION...
DAY 4-5...SEVERE POTENTIAL SHOULD REMAIN LOW THROUGH AT LEAST DAY 5
WITH A CUTOFF UPPER LOW MOVING SLOWLY THROUGH THE SERN U.S. AND
OFFSHORE FLOW OVER MOST OF THE GULF WITH THE EXCEPTION OF THE WRN
GULF DAY 5.

DAY 6-7...THREAT FOR SEVERE STORMS COULD INCREASE DAY 6-7 OVER TX.
MODELS CONTINUE TO ADVERTISE A SRN STREAM SHORTWAVE TROUGH THAT WILL
MOVE THROUGH TX AND THE LOWER MS VALLEY DURING THIS TIME.
HOWEVER...AMPLITUDE AND TIMING DIFFERENCES PERSIST AMONG
DETERMINISTIC RUNS AND ENSEMBLE MEMBERS. PRIMARY CONCERN IS DEGREE
OF MOISTURE RETURN IN ADVANCE OF THIS FEATURE. ECMWF IS SLOWER
MOVING THE ERN U.S. TROUGH OFF THE ATLANTIC SEABOARD...RESULTING IN
LESS TIME FOR GULF MODIFICATION AND A MORE LIMITED RETURN OF LOW
LEVEL MOISTURE THAN THE GFS. GIVEN PERSISTENT MODEL DIFFERENCES AND
POTENTIAL FOR LIMITED MOISTURE RETURN...WILL MAINTAIN LOW
PREDICTABILITY THIS FORECAST.

..DIAL.. 11/14/2012

[srainhoutx]

12Z GFS suggests some impressive totals adding up from late Monday to next Wednesday. We will see...

[djjordan]

Now that rainfall would be most welcome. My lawn is thirsty.

[Andrew]

Looking at the GFS and other models next week could get a little interesting as mid level heights begin to drop out west in the pacific. Indications that a shortwave out west attached with deepening trough to the north should help increase rain chances around here. The latest GFS run tries to cut off a low west of Texas and could be something to watch in the coming days. Upper level winds are supportive of some mixing but looking at the latest soundings any stronger storms look limited especially with the potential of a dry layer in the lower levels. Looking at the longer range a good amount of cold air looks to build in NW Canada. As of now the zonal flow that has dominated much of this season looks to continue and until we can get a blocking agent out east that cold air will more than likely stay up north. Some things to keep an eye on for late November/ December.

[srainhoutx]

HGX issues Freeze Warning for Counties N of Harris, Waller & Liberty for tonight/early tomorrow morning.

[jasons2k]

I just noticed the freeze warning. It's a bit early in the season for this. And they had a significant freeze just N/NW of the DFW area back in early October - could this be a harbinger of things to come this season?

[Ptarmigan]

I just noticed the freeze warning. It's a bit early in the season for this. And they had a significant freeze just N/NW of the DFW area back in early October - could this be a harbinger of things to come this season?

Could be. I know some years when we had early freezes like in 1989 or 1993, there were freezes that winter. I also noticed first freezes often in mid November from 1969 to 1980, with the exception of 1971, in which the first freeze did not come until January 4, 1972 for winter of 1971-1972. Some of those November freezes from 1969 to 1980 gave way to some of the coldest winters on record, like 1972-1973, 1976-1977, and 1977-1978.

First to reach 32 at KIAH (1969 to 2011).

Code: Select all

Year	Month	Date
1969	11	14
1970	11	15
1971	13	4
1972	11	30
1973	12	8
1974	11	30
1975	11	14
1976	11	28
1977	11	10
1978	12	8
1979	11	14
1980	11	19
1981	12	18
1982	12	12
1983	12	7
1984	11	22
1985	12	2
1986	13	5
1987	11	12
1988	12	1
1989	10	20
1990	11	30
1991	11	4
1992	11	27
1993	10	31
1994	13	2
1995	12	10
1996	12	17
1997	11	17
1998	12	25
1999	11	3
2000	12	12
2001	12	26
2002	12	25
2003	12	14
2004	12	15
2005	12	6
2006	11	21
2007	12	17
2008	12	10
2009	12	4
2010	11	27
2011	12	7

13 means January of the following year for the fall and winter season to first reach 32.

[Andrew]

Looks like the number of places reaching freezing are going to be a little less than expected:

[srainhoutx]

A chilly 36 degrees up here in NW Harris County this morning. That temp is the 'coldest' reading so far for me this Fall season.

[srainhoutx]

I noted a large and very cold air mass in Canada and heading south. Will this polar air drive into south Texas and when might we expect the arrival.

We'll likely have to wait until after Thanksgiving before we see a big change in the pattern that would bring threats pushing that cold air this far S. Right now the pattern is such that we are stuck with a somewhat split pattern where storms systems enter Canada and drop into the Great Lakes Region and along the East Coast and High Pressure Ridge remains in control across the Great Basin and Intermountain West. There are 'hints' that the continued development of EC Coastal lows or potential Nor'easters are in the cards with a blocking regime over Greenland and the Hudson Bay Region as troughiness drop S to our E. What we'll need to watch for 'locally' is some increasing moisture next week in time for Thanksgiving. There are indications that a series of West Coast Pacific storms systems will increase snow cover across Canada and the Gulf will open up and moisture will increase next week. My hunch is a pattern change that may be conducive to allowing that building cold air to our N may begin to make intrusions into the Lower 48 the last week of November/early December. That said there appears to be little chance of El Nino developing during late Fall/Winter as some had speculated. That would tend to mean 'dryer' conditions across Texas unless we can get some sub tropical jet activity from the Eastern Pacific to cooperate. I also suspect the main storm track will be across Southern Colorado ejecting ENE into the Plains. That doesn't mean that we couldn't see a Coastal low develop from time to time, but those that had been hoping for a wet and cold winter may have to wait a while longer. We will see.

The overnight guidance is beginning to ‘sniff’ out the pattern change I mentioned several days ago. This morning we’ll look at what may happen as we head toward late November/early December and what ‘players’ are driving the changes expected.

The zonal flow of late of late has brought a very active period across the Pacific NW and Canada which has allowed a ‘fire hose’ of moisture with some rather chilly air to bring bouts of snow and even blizzard conditions along the northern tier of the CONUS and into Canada. Canada is well above where they were last year in snow cover due to this active pattern and a very cold air mass continues to build as the active pattern continues next week.

The changes that may well bring some of that building cold air S into the Lower 48 begin to show up in the long range guidance. There has been some warming in the stratosphere in the northern latitudes that we mention almost yearly as a potential indicator of building an Arctic Air Mass over the Polar Regions. Eurasia and Alaska as well as our source regions of Western Canada are cooling daily with temps now dropping to the -20’s in some locations and even lower in Siberia.

We look for several mechanisms or features that allow that cold air to spill S. One is a Polar Vortex that appears every winter. The other is MJO influences that we speak of during tropical season, but during winter often lead to a NE Pacific ridge of high pressure along the California Coast or +PNA.

11162012 00Z GFS gfs_namer_324_500_vort_ht.gif

Another indicator we look for is a West based –NAO (North Atlantic Oscillation) and a blocking Ridge pattern near Greenland which causes the jet stream to buckle over the North America. Last year we saw a very persistent Vortex or large low pressure complex over Alaska that would not allow any cold air to spill S and never ending SW winds in NW Canada keeping temps much above normal in our source regions with very little moisture or snow cover. This year that has not been the case. The $64,000 question is will the sub tropical jet become involved bring moisture over the cold air at the surface from the Eastern Pacific? That remains to be seen. That said as we have seen this week and will see again next week, disturbances are riding along that sub tropical jet and it appears it may stay a bit noisy for the next several weeks. We look ahead to what next we may bring a bit later, but I thought those looking for some cold weather may be interested to see that we may not have to wait that much longer. We will see…

11162012 00Z GFS 00zgfs850mbTAnomalyNA360.gif

11162012 00Z GFS 00zgfs850mbTSLPp12360.gif

[srainhoutx]

The pattern heading into Thanksgiving week suggests some embedded upper air disturbances will sweep across Texas via the noisy sub tropical jet. A return flow from the Gulf should allow for modest moisture to flow inland ahead of these disturbances as a zonal flow continues throughout the week. Light precip is possible Tuesday and again on Thursday/Friday, but rainfall amounts will be light at best. I hope everyone has a great Thanksgiving Holiday!

[jasons2k]

Dang - I'm late to the party...appears the Mon-Wed storm I was looking forward to has vaporized. Time to break out the sprinklers. Getting more and more concerned for next year's drought outlook.

[txflagwaver]

HIGH 70'S ON THANKSGIVING IS NOT RIGHT!! WE NEED COLD AIR NOW!
IT SHOULD BE FREEZING COLD/SNOWING ON THANKSGIVING. WHAT IS GOING ON???

[Rip76]

Dull weather, but two Texas NFL teams on TV for Thanksgiving.

And one Texas college team.

[srainhoutx]

The 18Z GFS joins the 12Z Euro that I mentioned in the December thread suggesting a fairly big shift in the pattern as we end November and head towards December. Brrr....

[srainhoutx]

The 00Z Euro and 12Z GFS continue to advertise some mighty big changes ahead in the pattern for late November/early December...stepping down...

00Z Euro:

11182012 00Z Euro 00zeuro500mbHeightAnomalyNA240.gif

11182012 00Z Euro 00zeurohourly850mbTempAnomalyNA240.gif

12Z GFS:

11182012 12Z GFS 12zgfs500mbHeightAnomalyNA240.gif

11182012 12Z GFS 12zgfs850mbTAnomalyNA240.gif

[tireman4]

Stepping down...woo hoo... great words to hear!!!

[srainhoutx]

It's not just the GFS that is cold. The Euro and GFS continue to advertise the first true Arctic front of the season arriving just as we end November...