November 2014: Nice Seanonal Thanksgiving Ahead

[Katdaddy]

Well stated by Jeff……"For what it is worth this is a historical flood setup in the state of TX and in the past similar setups with a stalling frontal boundary, deep upper trough SW of TX, and the remains of an eastern Pacific hurricane have produced devastating flooding in October 1994, October 1998, October 2002, and October 2006."

Interesting weather ahead next week so enjoy this beautiful weather and stay tuned.

[srainhoutx]

The 12Z GFS suggests a Coastal Low will develop next Wednesday along the Lower Texas Coast and move NE along Coastal Texas in SW Louisiana by Thursday afternoon. The GFS is also suggesting some rainfall amounts may approach the 5-8 inch range as the cut off upper low moves off the Upper Texas Coast later next week.

[tireman4]

I have a feeling this will be an interesting November for many folks. Stay tuned.

[srainhoutx]

The 7 Day Quantitative Precipitation Forecast increased rather dramatically this afternoon.

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1159 AM EDT FRI OCT 31 2014

VALID 12Z MON NOV 03 2014 - 12Z FRI NOV 07 2014

...VERY HEAVY PCPN PATTERN ON TAP FOR THE S-CENTRAL AND NWRN US
NEXT WEEK...

...PATTERN OVERVIEW AND GUIDANCE/UNCERTAINTY ASSESSMENTS...

WPC SURFACE FRONTS/PRESSURE AND 500 MB PROGS ALONG WITH ASSOCIATED
HPCGUIDE HIGH RESOLUTION SENSIBLE WEATHER GRIDS HAVE BEEN
PRIMARILY DERIVED FROM A BLEND OF THE 06 UTC GFS ENSEMBLE MEAN AND
THE REASONABLY COMPATABLE 00 UTC ECMWF/NAEFS ENSEMBLE MEANS. AN
ENSEMBLE MEAN FORECAST APPROACH WAS USED IN PART DUE TO LESS THAN
STELLAR DETERMINISTIC MODEL RUN TO RUN VARIANCE. GUIDANCE THOUGH
DOES SEEM TO BE CONVERGING UPON A MORE COMMON MID-LARGER SCALE
SOLUTION...BOLSTERING FORECAST CONFIDENCE... ESPECIALLY WITH HEAVY
PCPN THREATS FOR THE S-CENTRAL AND NWRN US NEXT WEEK.

THE WPC SOLUTION LEANS ON THE MORE AMPLIFIED SIDE OF THE FULL
ENVELOPE OF SOLUTIONS FOR BOTH THE NRN AND SRN STREAMS...FOLLOWING
FROM LEAD-IN WATER VAPOR IMAGERY LOOP ANALYSIS...OVERALL GUIDANCE
TRENDS/BIASES...AND RECENT FLOW HISTORY.


...SENSIBLE WEATHER HIGHLIGHTS...

AMPLIFIED YET STEADILY PROGRESSIVE MID-UPPER LATITUDE FLOW
SUPPORTS SEVERAL FRONTAL SYSTEM PUSHES FROM THE CENTRAL TO ERN US
NEXT WEEK WITH MODEST PCPN. ENSEMBLE MEANS ARE MODESTLY MORE
AMPLIFIED THAN THE DETERMINISTIC GFS/ECMWF OVER TIME IN THIS
PATTERN. HOWEVER...A BIGGER THREAT TRAILS BACK AND LINGERS OVER
THE S-CENTRAL US WHERE SLOWER MOVING BOUNDARIES AND POTENTIAL SRN
STREAM MID-UPPER LEVEL TROUGH SUPPORT WORKING SLOWLY FROM THE SWRN
US/MEXICO MAY COMBINE WITH DEEPER GULF OF MEXICO MOISTURE INFLOW
THAT MAY BE FURTHER ENHANCED TO SOME FACTOR BY MID-UPPER LEVEL
MOISTURE FED UP FROM ERN PAC TS VANCE. FYI...THE EXPERIMENTAL
PARELLEL 06 UTC GFS HAS TRENDED MORE IN LINE WITH THE 00 UTC ECMWF
IN THE SRN STREAM NEXT WEEK.

MEANWHILE...ENERGETIC MID-UPPER LATITUDE FLOW ALSO FAVORS A
PROLONGED HEAVY PCPN PATTERN FOR THE NWRN US WHERE A MOIST FETCH
WITH EACH SYSTEM APPROACH/PASSAGE IS SIGNIFICANTLY ENHANCED BY
TOPOGRAPHY.

SCHICHTEL

[Ptarmigan]

The 7 Day Quantitative Precipitation Forecast increased rather dramatically this afternoon.

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1159 AM EDT FRI OCT 31 2014

VALID 12Z MON NOV 03 2014 - 12Z FRI NOV 07 2014

...VERY HEAVY PCPN PATTERN ON TAP FOR THE S-CENTRAL AND NWRN US
NEXT WEEK...

...PATTERN OVERVIEW AND GUIDANCE/UNCERTAINTY ASSESSMENTS...

WPC SURFACE FRONTS/PRESSURE AND 500 MB PROGS ALONG WITH ASSOCIATED
HPCGUIDE HIGH RESOLUTION SENSIBLE WEATHER GRIDS HAVE BEEN
PRIMARILY DERIVED FROM A BLEND OF THE 06 UTC GFS ENSEMBLE MEAN AND
THE REASONABLY COMPATABLE 00 UTC ECMWF/NAEFS ENSEMBLE MEANS. AN
ENSEMBLE MEAN FORECAST APPROACH WAS USED IN PART DUE TO LESS THAN
STELLAR DETERMINISTIC MODEL RUN TO RUN VARIANCE. GUIDANCE THOUGH
DOES SEEM TO BE CONVERGING UPON A MORE COMMON MID-LARGER SCALE
SOLUTION...BOLSTERING FORECAST CONFIDENCE... ESPECIALLY WITH HEAVY
PCPN THREATS FOR THE S-CENTRAL AND NWRN US NEXT WEEK.

THE WPC SOLUTION LEANS ON THE MORE AMPLIFIED SIDE OF THE FULL
ENVELOPE OF SOLUTIONS FOR BOTH THE NRN AND SRN STREAMS...FOLLOWING
FROM LEAD-IN WATER VAPOR IMAGERY LOOP ANALYSIS...OVERALL GUIDANCE
TRENDS/BIASES...AND RECENT FLOW HISTORY.


...SENSIBLE WEATHER HIGHLIGHTS...

AMPLIFIED YET STEADILY PROGRESSIVE MID-UPPER LATITUDE FLOW
SUPPORTS SEVERAL FRONTAL SYSTEM PUSHES FROM THE CENTRAL TO ERN US
NEXT WEEK WITH MODEST PCPN. ENSEMBLE MEANS ARE MODESTLY MORE
AMPLIFIED THAN THE DETERMINISTIC GFS/ECMWF OVER TIME IN THIS
PATTERN. HOWEVER...A BIGGER THREAT TRAILS BACK AND LINGERS OVER
THE S-CENTRAL US WHERE SLOWER MOVING BOUNDARIES AND POTENTIAL SRN
STREAM MID-UPPER LEVEL TROUGH SUPPORT WORKING SLOWLY FROM THE SWRN
US/MEXICO MAY COMBINE WITH DEEPER GULF OF MEXICO MOISTURE INFLOW
THAT MAY BE FURTHER ENHANCED TO SOME FACTOR BY MID-UPPER LEVEL
MOISTURE FED UP FROM ERN PAC TS VANCE. FYI...THE EXPERIMENTAL
PARELLEL 06 UTC GFS HAS TRENDED MORE IN LINE WITH THE 00 UTC ECMWF
IN THE SRN STREAM NEXT WEEK.

MEANWHILE...ENERGETIC MID-UPPER LATITUDE FLOW ALSO FAVORS A
PROLONGED HEAVY PCPN PATTERN FOR THE NWRN US WHERE A MOIST FETCH
WITH EACH SYSTEM APPROACH/PASSAGE IS SIGNIFICANTLY ENHANCED BY
TOPOGRAPHY.

SCHICHTEL

Possible flooding event? QPF tend to underestimate rainfall amount.

[srainhoutx]

Just a little bit chilly out there this morning. Dropped to 48F in NW Harris County and I see the usually cold spot in Conroe hit 39F. Enjoy the day...the weather will be changing next week. It still looks wet and potentially wet most of next week depending on the eventual evolution of the meandering cut off low/trough.

[Texaspirate11]

Our first freeze warnings - say it isn't so

...THE FIRST FREEZE OF THE SEASON IS EXPECTED INTERIOR SOUTHEAST
TEXAS AND CENTRAL LOUISIANA TONIGHT...

.COLD POLAR AIR HAS SPREAD SOUTH INTO THE REGION. AFTER NORTHERLY
WINDS ABATE...TEMPERATURES WILL QUICKLY FALL TO THE LOWER 30S AND
POSSIBLY BELOW THE FREEZING MARK AT SOME LOCATIONS ACROSS INTERIOR
SOUTHEAST TEXAS AND CENTRAL LOUISIANA.

LAZ027>029-TXZ259-260-021300-
/O.EXT.KLCH.FZ.W.0002.141102T1000Z-141102T1300Z/
VERNON-RAPIDES-AVOYELLES-NORTHERN JASPER-NORTHERN NEWTON-
INCLUDING THE CITIES OF...LEESVILLE...NEW LLANO...ALEXANDRIA...
PINEVILLE...MARKSVILLE...BUNKIE...COTTONPORT...SIMMESPORT...
MANSURA...JASPER...KIRBYVILLE...NEWTON
547 PM CDT SAT NOV 1 2014

...FREEZE WARNING NOW IN EFFECT FROM 4 AM TO 7 AM CST SUNDAY...

* TEMPERATURE...LOWS DOWN TO 30 DEGREES EXPECTED.

* IMPACTS...TENDER VEGETATION IN DANGER OF FREEZING DURING THE
FREEZE WARNING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FREEZE WARNING MEANS SUB-FREEZING TEMPERATURES ARE IMMINENT OR
HIGHLY LIKELY. PEOPLE SHOULD TAKE MEASURES TO PROTECT PLANTS BY
COVERING THEM OR BRINGING THEM INSIDE. ALSO...PETS SHOULD BE
PROTECTED OR MOVED INDOORS.

BE CAREFUL HEATING YOUR HOME. SPACE HEATERS NEED TO BE KEPT
36 INCHES AWAY FROM ANYTHING THAT CAN BURN. TURN IT OFF WHEN YOU
LEAVE THE ROOM OR GO TO BED.

[Katdaddy]

51F and dropping. Ready to say hello to the 40s even though I love my 90s. Perhaps a snow event for SE TX during the 2014-2015 Winter.

[srainhoutx]

42F the morning in NW Harris County with breezy E winds developing as the ridge of high pressure that brought snow across portions of the Carolinas yesterday morning shifts E. A return flow off the Gulf will increase today and tomorrow as the Western trough begins to cross New Mexico and leeside cyclogenesis begins along the front range of the Colorado Rockies. Tuesday into Wednesday looks very wet and stormy as a cold front marches across Texas and taps both Pacific and Gulf moisture. The front should clear the Coast sometime on Thursday as the Coastal Low heads NE and drier air filters in at the surface. We may hang on to clouds behind the front as soon to be EPAC Hurricane Vance nears the Baja Peninsula and weakens. the long fetch tap of Pacific moisture may keep us cloudy and cool to end the upcoming work week.



Attention then turns to our NW as a Ridge develops off the Coast of California and extends up into Alaska. This is indicative of a +PNA/-AO/-EPO pattern that many of the long range Meteorologists have been indicating as El Nino fully develops. Cold air that has been building in Canada may begin to push S next weekend as a strong front enters the Lower 48. Some of the longer range computer models are suggesting a potential big late Fall/early Winter type storm may develop across the Southern Plain near the November 12th-14th timeframe, but that is too far out to speculate in a casual nature as we look ahead to what may lie ahead as we head toward the end of November into December.

[Portastorm]

Hit bottom at 42 degrees here (SW Austin) this morning at the Portastorm Weather Center.

Noticed that Joe Bastardi tweeted this morning showing the latest long-range CFSv2 forecast map for the period mid November through mid December. It looks rather cold for central and eastern areas of the nation, including our Lone Star State.

[cperk]

Anyone care to on out on a limb about our Thanksgiving weather.

[srainhoutx]

Hit bottom at 42 degrees here (SW Austin) this morning at the Portastorm Weather Center.

Noticed that Joe Bastardi tweeted this morning showing the latest long-range CFSv2 forecast map for the period mid November through mid December. It looks rather cold for central and eastern areas of the nation, including our Lone Star State.

The CFS is not only chilly...but wet. That would also be indicative of a noisy sub tropical jet with potential for Coastal Lows to develop along the NW Gulf Coast which is a pattern we typically see in a weak developing El Nino Pattern across our Region. Again, this is all speculative that far out, but the teleconnection (-Arctic Oscillation/+Pacific North America/-East Pacific Oscillation as well as a +Pacific Decadal Oscillation) indices we look to in long range forecasting are indications we could be heading into an eventful weather pattern to end November into December. We will see.

[srainhoutx]

The 12Z computer guidance is slowly coming into agreement regarding the heavy rainfall threat this week. The wildcard is what will happen at the base of the incoming Western trough and whether or not a closed cut off low develops over Mexico. That said the models do paint a very wet and stormy Tuesday and Wednesday as the frontal boundary advances across Texas.

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
158 PM EST SUN NOV 02 2014

VALID NOV 02/1200 UTC THRU NOV 06/0000 UTC

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

==============================================
12Z MODEL EVALUATION AND PREFERENCES
==============================================
NAM/GFS INITIALIZATION ERRORS DO NOT APPEAR TO
SIGNIFICANTLY AFFECT THEIR LARGE SCALE OUTPUT.
==============================================

...SOUTHWEST U.S. TROUGH LEADING TO HEAVY RAIN FROM TEXAS
NORTHEASTWARD...

PREFERENCE: BLEND OF 12Z GFS/ECMWF
CONFIDENCE: SLIGHTLY BELOW AVERAGE

A POSITIVELY TILTED TROUGH AND ASSOCIATED FRONTAL ZONE WILL
PROMOTE A WIDESPREAD RAINFALL EVENT FROM TEXAS INTO THE
MISSISSIPPI VALLEY AND NORTHEASTWARD. TODAY HURRICANE VANCE WAS IN
THE EASTERN PACIFIC WELL SOUTHWEST OF MANZANILLO MEXICO PER THE
NHC POSITION. UPPER LEVEL MOISTURE FROM THE TROPICAL CYCLONE IS
LIKELY TO BECOME ENTRAINED IN THE MID LATITUDE TROUGH AFFECTING
THE U.S. BY DAY 2...WITH MID LEVEL MOISTURE POSSIBLY ARRIVING BY
DAY 3. THIS COULD YIELD A MORE FOCUSED HEAVY RAIN THREAT BEGINNING
WITH TEXAS ON DAY 3.

WHILE THESE GENERAL IDEAS ARE WELL RESOLVED IN THE MODELS THERE IS
STILL A GREAT DEAL OF SPREAD AS TO HOW THE BASE OF THE MID LEVEL
TROUGH WILL BEHAVE OVER THE RIO GRANDE VALLEY. INDIVIDUAL MODELS
AND EVEN THE ENSEMBLE MEANS ARE SHOWING SOME MODERATE VARIABILITY
FROM RUN TO RUN. AT 00Z MOST OF THE COMMONLY REFERENCED MODELS AND
ENSEMBLE MEANS TRENDED FASTER AND MORE OPEN...BUT A NUMBER OF
ENSEMBLE MEMBERS STILL RETAINED A SLOWER MOVING CLOSED CIRCULATION
IN THE RIO GRANDE VALLEY. AT 12Z...MOST GUIDANCE TRENDED BACK
TOWARD THE SLOWER...MORE CLOSED LOOK. THESE DETAILS APPEAR TO HAVE
LIMITED INFLUENCE ON THE SURFACE FRONTAL ZONE...HOWEVER...WHICH
CONTINUES TO DRIVE STEADILY SOUTH AND EASTWARD GIVEN LARGE SCALE
HEIGHT FALLS OWING TO THE NORTHWARD EXTENSION OF THE TROUGH...AND
PERHAPS DRIVEN BY WIDESPREAD PRECIPITATION. RUN TO RUN CHANGE IN
THE SURFACE SOLUTION AND QPF IS LESS PRONOUNCED.

GENERALLY THE GFS AND ECMWF HAVE TENDED TO LAND SOMEWHERE NEAR THE
MIDDLE OF THE SPREAD...AND THEIR PRECIPITATION FORECASTS LINE UP
WELL WITH THE ENSEMBLE MEANS. THE NAM WAS THE ONE MODEL THAT
CONTINUED TO FORECAST A PARTICULARLY OPEN AND PROGRESSIVE
WAVE...AN IDEA WHICH HAS LESS SUPPORT.

[srainhoutx]

A quick look at the longer range 12Z 11/02/2014 European computer guidance because I know there is a lot of 'chatter' concerning the potential cold and stormy pattern across the various website and social media. The Global models are slowly coming together suggesting a developing pattern conducive for bringing a lot of the cold and snowy Canadian air well south into the Central and Eastern United States. As always, I'll offer a word of caution as we know all too well that computer guidance beyond 5 days is going to change...and sometimes daily. That said and as mentioned earlier today, the teleconnection indices are increasing lending to a bit of confidence that the models are 'sniffing' out a significant pattern change. Add to the mix Super Typhoon Nuri that should pass E of Japan as it transitions to a powerful extra tropical storm in or near the Bering Sea in about a week, the interest increases and raises an eyebrow regarding the potential sensible weather we could see across our Region near the mid November timeframe.

The attachment 11022014 12Z Euro 240 ecmwf_z500a_namer_11.png is no longer available

[srainhoutx]

Evening briefing form Jeff:

Widespread heavy rainfall likely Tuesday-Thursday

Ingredients coming together to produce a heavy rainfall event over a large part of TX this week potentially making a significant dent in the ongoing hydrological drought over central TX.

Deep upper air trough will dig into the SW US and northern MX early this week turning the flow over TX out of the SW aloft. This trough is starting to capture hurricane Vance off the SW MX coast turning the system northward and this trend should continue allowing mid and high level moisture to begin to spill northeastward into TX. Cold surface high pressure is moving eastward allowing Gulf moisture to begin its return at the low levels to the state. This is clearly noted by a dewpoint of 55 at Victoria versus 36 at Lufkin currently.

A cold front in association with the upper level trough will move into TX on Monday and enter SE TX late Tuesday and progress to the coast on Wednesday. By late Tuesday the air mass will saturate as moisture from both Vance and the Gulf combine over the state. The cold front becomes increasingly parallel to the upper level SW flow which will result in a favorable echo training pattern.

While the global models have converged on a more progressive system, moisture levels are forecasted to rise to a staggering 2.20 inches of PW at CRP which is +3 standard deviations above normal for early November. Strong frontal lift and favorable jet dynamics along the boundary working on a highly moist air mass paints a very wet mid week period. The threat for cell training induced flash flooding is high from late Tuesday into most of Wednesday. I am concerned with such moist values the models are and have been showing now for days and the potential for organized heavy training rainfall.

Frontal boundary should reach the coast late Wednesday, but base of the upper trough is slower to move eastward allowing moisture to flow up and over the surface cool pool resulting in continued light to moderate rainfall into Thursday.

Rainfall Amounts:
Still early to attempt to narrow down any one area that may see the greatest amounts. The event looks widespread over a large part of the state with widespread totals on average of 2-4 inches. Isolated amounts upwards of 6 inches are certainly possible and I would venture that a few locations will see a foot of rainfall before this event is done.

Short fused flash flooding will be the main concern under the training excessive rainfall cells in urban areas and across the hill country/flash flood alley area with a large scale hydrological response likely on all river basins due to the large QPF fields being predicted. While it is too early to be certain of the location of the highest rainfall amounts, the potential for rises of watersheds to flood stage is certainly possible by mid to late week.

It should be noted that WPC has outlooked a large part of TX and all of SE TX for excessive rainfall on their Day 3 outlook and an upgrade to a moderate or even high risk is possible as the event onset nears and confidence increases on the location of the greatest rainfall.

Flash Flood Watches will likely be needed for large portions of the state including most if not all of SE TX by Tuesday evening into Wednesday.

[Katdaddy]

Temps will approach 80 with more humidity across SE TX. and few showers along the coast. A heavy rain event looks likely for Central, SE, and E TX Tuesday night through Wednesday night thanks to an approaching trough, moisture from TC Vance, and cool front. Perhaps another perfect weather weekend.

[SLM87TX]

When will storm kick off with this system for our area during the day or more into the night?

[dljones33]

I'm going shopping tomorrow so I hope the rain won't arrive till evening!

[srainhoutx]

When will storm kick off with this system for our area during the day or more into the night?

Tuesday evening into the overnight hours looks like the best chance of the heavier training rainfall along and behind the frontal boundary.

[SLM87TX]

Looking at current WPC, looks like training effect might form over lower hill country or NW Southeast TX or just below the Balconies. Wish it would start up in the Hill Country. Fill up them lakes. It has before.