January 2017 -Warming Trend To End The Month

[Katdaddy]

Areas of rain currently moving across SE TX should decrease and move E by NYE however dense fog will become an issue tonight. A severe weather threat comes into the picture for Sunday night and Monday morning with a Slight Risk area across a large portion of TX as Srain posted.

[Portastorm]

Concern increasing here in south central Texas as well about a possible severe weather event late Sunday into early Monday.

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[snowman65]

I think its safe to say the winter has been a major flop. Lets just put it behind us, move on to spring and start fishing.

[srainhoutx]

I think its safe to say the winter has been a major flop. Lets just put it behind us, move on to spring and start fishing.

I believe it is way too soon to call flop on Winter or even the cold expected this week as of New Years Eve. The overnight Teleconnection Indices suggest major changes are brewing in our Hemispheric Pattern and it is not unusual to see extreme run to run volatility in the Computer schemes. Those computer models just cannot handle the extremes that other data provides to our weather tool box of forecasting. The various features that we will need to watch are across the Pacific Ocean and some of the embedded disturbances cannot be determined beyond a day or two. I offer what happened yesterday with sleet falling as a prime example. Even with the best data and upper air sampling available, the models totally missed the very shallow warm layer at the surface and the very dry and cold air aloft that allowed the sleet pellets to form. One of the many things that make weather so fascinating and peak the interest of both the Professional Forecaster and the weather enthusiast are those unknown surprises that we so often see watching the weather patterns. That's what brings all of us to this Weather Community and others...this wacky unpredictable thing that effects us all...the weather!

[cperk]

I think its safe to say the winter has been a major flop. Lets just put it behind us, move on to spring and start fishing.

It's not even January yet.

[srainhoutx]

The morning Updated Weather Prediction Center clearly explains the volatility in their Extended Range Outlook and that the various models schemes are flip flopping leading to a very low confidence forecast beyond Tuesday...

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1059 AM EST SAT DEC 31 2016

VALID 12Z TUE JAN 03 2017 - 12Z SAT JAN 07 2017

...OVERVIEW...

GUIDANCE IS STILL SHOWING SIMILAR IDEAS FOR THE LARGE SCALE
EVOLUTION BUT OFFERS SIGNIFICANT SPREAD AND RUN-TO-RUN CHANGES FOR
VERY IMPORTANT EMBEDDED DETAILS THAT WILL AFFECT SENSIBLE WEATHER
OVER PARTS OF THE WEST AND LOCATIONS DOWNSTREAM. THE MOST
CONFIDENT ASPECT OF THE FCST IS FOR WELL BELOW NORMAL TEMPS
EXTENDING FROM THE NRN-CNTRL WEST INTO THE PLAINS WITH LESSER COLD
ANOMALIES EXTENDING INTO THE EAST. MOST MODEL/ENSEMBLE SOLNS
AGREE IN PRINCIPLE THAT A VERY STRONG UPR HIGH OVER THE NERN PAC
AS OF TUE WILL RETROGRADE/MERGE WITH A BUILDING BERING SEA RIDGE
BY AROUND THU TO YIELD A MEAN RIDGE NEAR 160-170W LONGITUDE INTO
SAT. IN RESPONSE A DEEPENING TROUGH SHOULD DEVELOP OFF THE PAC
NW/BC COAST FRI-SAT. THIS EVOLUTION SHOULD KICK OUT INITIAL WEST
COAST UPR LOW TROUGH/ENERGY BUT WITH VERY UNCERTAIN TIMING/SHAPE.
OVER THE ERN HALF OF THE CONUS VARYING DEGREES OF CYCLONIC FLOW
SHOULD PREVAIL... REPRESENTING SOME DISTANT INFLUENCE FROM
POSITIVE HGT ANOMALIES OVER THE NRN ATLC.


...GUIDANCE/PREDICTABILITY ASSESSMENT...

AT THE VERY START OF THE PERIOD THE PRIMARY UNCERTAINTY IS WITH
THE COMPLEX SYSTEM AFFECTING THE ERN U.S. TUE-WED. GFS/GEFS MEAN
RUNS CONTINUE TO BE ON THEIR OWN WITH A MORE WRAPPED UP SYSTEM
SFC/ALOFT AS OF EARLY TUE. ON THE OTHER HAND OTHER 00Z MODELS
HAVE DELAYED CONSOLIDATION BY ABOUT 12-24 HRS VS PRIOR 12Z-00Z
RUNS. OVERALL PREFERENCE WAS TO MAINTAIN AN INTERMEDIATE SOLN
CLOSEST TO CONTINUITY... NOT AS WRAPPED UP AS THE GFS BUT
CONSOLIDATING EARLIER THAN THE 00Z ECMWF/UKMET/CMC. CONSULT THE
MODEL DIAGNOSTIC DISCUSSION PMDHMD FOR UPDATED PREFS BASED ON NEW
12Z GUIDANCE THROUGH 00Z WED.

AS CAN FREQUENTLY BE THE CASE WITH ENERGY TO THE S/SE OF UPR
HIGHS... GUIDANCE IS HAVING CONSIDERABLE DIFFICULTY IN RESOLVING
WHAT HAPPENS TO ELONGATED ENERGY INITIALLY ALONG/OFFSHORE THE PAC
NW COAST. 00Z ECMWF/ECMWF MEAN RUNS MADE A DRASTIC CHANGE FROM
PREVIOUS RUNS... NOW PULLING THE ENERGY FARTHER WWD AND EVEN
INCORPORATING SOME SEPARATE UPSTREAM MID-LATITUDE ENERGY TO YIELD
A LENGTHY PERIOD OF VERY MOIST FLOW IMPACTING THE NRN HALF OF CA
BEFORE THE OFFSHORE UPR LOW EVENTUALLY TRACKS INLAND. OTHER SOLNS
DO NOT LOOK LIKE THE ECMWF/ECMWF MEAN BUT STILL VARY GREATLY IN
THE TIMING AND SHAPE/AMPLITUDE OF THE WEST COAST ENERGY AS IT
PROGRESSES ACROSS THE LOWER 48. THE ONE SIGNAL THAT APPEARS TO BE
EVIDENT FROM MORE THAN HALF OF GUIDANCE AS A WHOLE IS POTENTIAL
FOR SLOWER EJECTION OF THE INITIAL WEST COAST ENERGY. THIS WOULD
LEAD TO LESS PHASING WITH NRN STREAM FLOW AND DELAYED EXPANSION OF
THE LEADING MSTR SHIELD WHICH COULD CONTAIN SOME WINTRY PCPN TYPES
OVER THE CNTRL-ERN STATES.

ASIDE FROM THE 06Z GFS PERHAPS DRIFTING A LITTLE TOO CLOSE TO THE
PAC NW COAST WITH ITS AMPLIFYING OFFSHORE TROUGH FRI-SAT AND THE
00Z GFS BEING A TAD STRONG WITH ITS EJECTING SHRTWV REACHING THE
PLAINS SAT... THERE IS BETTER THAN AVG AGREEMENT IN THE GUIDANCE
ALOFT BY THE END OF THE PERIOD. SFC DETAILS ARE MUCH LESS
CERTAIN. DIFFS IN HOW THE AMPLIFYING NERN PAC TROUGH INTERACTS
WITH THE TROUGH/UPR LOW FARTHER TO THE SW AFFECT THE ERN PAC/WEST
COAST SFC PATTERN. ENSEMBLE MEANS ARE QUITE SIMILAR THOUGH. OVER
THE ERN STATES THE EFFECTS OF A WAVY FRONT FROM THE GULF INTO THE
WRN ATLC WILL BE SENSITIVE TO SHRTWV DETAILS ALOFT.

LACK OF CONFIDENCE IN ANY SPECIFIC SCENARIO IN THE 00Z/06Z CYCLES
FAVORS ONLY MODEST ADJUSTMENT FOR NEW GUIDANCE. THUS THE LATEST
UPDATE INCORPORATES HALF WPC CONTINUITY AND THE REST FROM THE 06Z
GEFS/00Z NAEFS/00Z ECMWF MEANS.


...WEATHER HIGHLIGHTS/THREATS...

EXPECT COLDEST TEMPS RELATIVE TO NORMAL FROM THE INTERIOR
NORTHWEST INTO THE NRN PLAINS WHERE THERE COULD BE MULTIPLE DAYS
WITH HIGHS AND/OR LOWS 20-30F BELOW NORMAL WITH LOCALLY COLDER
ANOMALIES. AT LEAST A FEW DAILY RECORDS ARE PSBL. THE CNTRL HIGH
PLAINS MAY SEE HIGHS AT LEAST 20F BELOW NORMAL FOR A TIME AS WELL.
TUE-WED SYSTEM AFFECTING THE EAST WILL BRING WARMTH TO THE EAST
EARLY IN THE PERIOD WITH ANOMALIES OF PLUS 10-20F FOR HIGHS AND AS
MUCH AS PLUS 20-30F FOR MORNING LOWS. THEN COLDER AIR WILL FILTER
IN BUT WITH LESS EXTREME COLD ANOMALIES THAN OVER THE WEST/PLAINS.

THE TUE-WED ERN SYSTEM WILL BE ACCOMPANIED BY AREAS OF ENHANCED
WARM SECTOR RNFL AND SNOW OR RAIN CHANGING TO SNOW IN THE MID-UPR
GRTLKS... ALONG WITH BRISK WINDS OVER SOME AREAS. COLD CYCLONIC
FLOW ALOFT BEHIND THE SYSTEM SHOULD SUPPORT PERIODS OF LAKE EFFECT
SNOW.

OVER THE WEST... IN SPITE OF THE SPREAD IN GUIDANCE FOR DETAILS
ALOFT THERE IS A COMMON THEME TOWARD HIGHEST PCPN TOTALS BEING
OVER NRN-CNTRL CALIFORNIA WITH LESSER AMTS EXTENDING INTO THE
FAVORED TERRAIN OF THE CNTRL/S-CNTRL ROCKIES. HOWEVER TIMING AND
INTENSITY OF PCPN IS QUITE UNCERTAIN. THE MEAN PATTERN DOES FAVOR
THE NRN-CNTRL CA AREA FOR BEST PCPN CHANCES THOUGH. THE PAC NW
SHOULD SEE AN INCREASE IN MSTR DURING THE LATTER HALF OF THE
PERIOD AS UPR TROUGHING AMPLIFIES OFFSHORE.

INITIAL QUESTION MARKS OVER THE WEST LEAD TO VERY LOW CONFIDENCE
IN COVERAGE/INTENSITY OF PCPN OVER THE CNTRL-ERN STATES FROM THE
LATTER HALF OF THE WEEK INTO THE WEEKEND... WITH THE CURRENT RANGE
IN POSSIBILITIES RANGING FROM A FAIRLY DRY PERIOD TO WIDESPREAD
COVERAGE OF PCPN WITH SOME WINTRY WEATHER IN THE NRN PART OF THE
MSTR SHIELD.

RAUSCH

[srainhoutx]

New Years Eve briefing from Jeff:

Severe thunderstorms with damaging winds and large hail will be possible late Sunday and early Monday across much of SE TX.

Lead short wave disturbance now moving E into SW LA with lessening rainfall coverage over SE TX. However upstream short wave digging down the CA coast will turn eastward and move across TX late NYD into early Monday with a round of strong to severe thunderstorms. Large warm sector will develop northward over C and E TX on Sunday ahead of this strong short wave with mid to upper 60 degrees dewpoints overspreading all of SE TX by early evening NYD. Warm sector should remain capped due to moderate intensity elevated mixed layer advecting ENE from NE MX on top of low level stratus cloud deck from the Gulf inflow.

Air mass will be moderately unstable by Sunday night with 1000-1500 J/kg CAPE over the region and strong shearing profiles as lift from approaching potent short wave overspreads the region. Showers and thunderstorms may initiate in low level convergent zone along/SE of US 59 toward midnight if mid level capping can be overcome. These storms would likely be near surface based and feed off the favorable low level Gulf inflow and shear profiles…so there could be an isolated tornado threat. Bigger event will be strong lift spreading into the warm sector across C TX which should result in the development of numerous strong to scattered severe thunderstorms which will grow upscale into a squall line or forward propagating MCS. Main severe threats with this activity appear to be large damaging hail and strong winds. Low level jet of 40-45kts and carving mid level winds support bowing line segments and potential for corridors of wind damage. Best timing will be between midnight and 900am Monday morning for activity to impact SE TX.

Current SPC Day 2 slight risk outline covers the threat well and unless better instability is found on Sunday with better surface heating or a weaker cap across the warm sector think the isolated tornado threat Sunday evening ahead of the main line of storms is fairly low.

Day 2 (Sunday night/early Monday) Severe Weather Outlook:

Late Next Week:
Global models have generally backed away from a strong arctic front and now suggest a more modified air mass (still cold) into the region Wednesday. For now will keep temperatures in the 50’s for highs and 40’s for lows Thursday and Friday of next week, but much colder temperatures will be possible if models swing back to the colder solutions…guidance has been less than stellar with the amount and intensity of cold air that might be delivered into TX by the end of next week. Models have also backed down on post frontal QPF potential, but maintain fairly extensive cloud cover for much of the late week period. Will need to continue to monitor this period for additional changes in guidance…but at this time any threat for winter precipitation looks less than a few days ago.

[Ptarmigan]

I think its safe to say the winter has been a major flop. Lets just put it behind us, move on to spring and start fishing.

A warm December does not necessarily mean winter will be warm. December 1984 was warm, while January and February 1985 were cold.

[StormOne]

I'll make a severe outlook graphic tomorrow specifically for this forum (I cover and forecast for Lincoln now, so you guys get a treat). Right now, looks like the biggest severe timeframe for the Houston metro will be between 3am-9am Monday morning, although if NAM verifies make that about 11pm-6am. Hail threat is present, but not outstanding. Wind and tornado threat are more prevalent. No strong tornadoes likely, that is near impossible in SE TX anyway, but don't be surprised if you get woken up with a tornado warning on your phone tomorrow night. Looks like an issue will be getting the cap to go away, although both GFS and NAM advertise that with no problem. Happy 2017, and be safe!

[srainhoutx]

The impulse that will bring our Severe Weather threat tonight into the early hours of Monday is round the base of a trough and should near West Texas this evening. The primary concern for severe weather will be damaging straight line winds and hail, particularly across portions of Central and N Texas. The greatest risk for an isolated tornado or two will be across portions of the I-35 Corridor in the Hill Country into the Brazos River Valley on SE into areas mainly N of I-10 and W of I-45. We will monitor the weather to our West later today and Update for the Dallas/Ft Worth, San Antonio/Austin of course SE Texas later tonight.

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[snowman65]

I already have azaleas blooming...lol

[Portastorm]

The severe wx threat late tonight for south central Texas looks decent. Large hail and maybe some isolated higher winds appear to be the most likely threats. Thankfully the storms are forecast to move through rather quickly and that should diminish a flash flood threat. Looks to move through the general Austin metro area between 3-6 am Monday.

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[srainhoutx]

Sunday afternoon briefing from Jeff:

Slight risk of severe thunderstorms tonight into early Monday for all of SE TX.

2017 starting off much like 2016 ended with warm and muggy conditions with sea fog along the coast and passing showers. Weak frontal boundary south of College Station will begin to lift back northward allowing an increasingly warm and moist warm sector to spread northward across much of C and E TX today. A potent short wave trough current over southern AZX will eject across TX tonight with strong lift coming to bear across the increasing warm sector. Expect thunderstorms to develop across the Pecos River valley of W TX this evening and spread ESE overnight into better moisture , instability and shear. Scattered development will grow upscale into a MCS after midnight along and just east of I-35 and push across SE TX between 300am and noon on Monday.

Given CAPE of 1000 J/kg, LI’s of -5 or greater and strong low level wind shear think damaging winds and large hail will be the main threats along any bowing line segments within the main line. Some potential for local surface convergence shown in several meso scale models to overcome warm sector capping and allow development of discrete cells ahead of the main line. While this development is conditional on the cap weakening, any storm that would develop ahead of the main line in any convergent low level flow could have a greater tornado threat. Most favored area continues to be shown along US 59 from roughly Wharton County to Liberty County possibly along some sort of low level convergent boundary where strong SE winds slow inland and veer to the S and SSW.

Storm system will be fast moving and should clear all areas by midday on Monday with clearing skies and increasing westerly winds which will actually help to warm temperatures behind the Pacific front. Could approach record highs on the coast as is common in westerly low level flow regimes in this area.

Modified arctic air mass will arrive in waves toward the end of the week with the first front on Wednesday followed by another surge of even colder air Thursday. Models are not and have not been in good agreement at all with the surface temperatures and QPF late this week…so will continue to monitor, but a period of fairly cold conditions looks likely from Thursday-Sunday.

Day 1 (Today) Severe Weather Outlook:

[StormOne]

TTU WRF advertises the peak storm threat being here mid-morning in the form of a disorganized multicellular line, basically still being multicell clusters when it passes thru SE TX. An isolated supercell wouldn't shock me (unless I get struck by lightning in said supercell ), but I do not think that will be the predominant storm mode. Would not be surprised to be kicked out of the slight risk area for Day 1, but have the entire metro placed in a slight risk area for Day 2 by the SPC. Good move putting in the 5% tornado risk area.

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[Andrew]

HRRR is coming into range also. HRRR suggests that a split line may develop with some more discrete cells further south over south central SE Texas. Looking at the GFS sounding for the region shows a decent looking hodograph with nice veering aloft. Biggest question will be instability. Only marginal instability will exist this far south but with such a strong shortwave i suggest we will see a line still develop.

[StormOne]

Going ahead and doing the severe outlook. My main concern is that I put each category (except flooding) too high, and this may need to be changed as everything evolves. Putting wind as the highest threat is a no-brainer, as in addition to preceding storms, the parent complex will obviously have wind as the main threat as it will likely be linear in nature. Hail and tornado threats were tougher. I originally contemplated putting tornado threat between low and moderate, and hail at low. However, I figured that putting hail lower than tornado threat would let the tornado threat shine way too much. Plus, a high-precipitation supercell would not surprise me. Therefore I put both between low and moderate. Flooding is not the biggest threat with this system, as training storms will not happen, but briefly heavy rain will likely make for brief street flooding, therefore I put that between none and low. The linear system should come by us regardless of any capping inversion in place. However, the main inhibitor for severe storms before the parent system would be a weak cap in place, although I do think that can be overcome. One thing I can tell you, looks like New Year's fireworks in the form of lightning will come one night too late. This system will be nothing out of the ordinary, no mass hysteria is necessary.

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[StormOne]

SPC's Day 1 outlook text for today and tomorrow up to 6am.

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER A PORTION OF
CENTRAL AND EASTERN TEXAS...

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM A PORTION
OF TEXAS INTO THE GULF COAST REGION...

...SUMMARY...
A marginal risk for isolated strong to severe thunderstorms
continues for this evening across a part of the central and eastern
Gulf Coast region. Meanwhile, a greater severe-weather threat is
expected to develop across portions of Texas later tonight.

...Far West TX and Pecos Valley to central and east TX...
Trends in the environment across central and east TX are gradually
destabilizing. Further moistening, given strengthening southerly
low-level winds, combined with a plume of steep midlevel lapse rates
(per 00z soundings across south through northwest TX) spreading east
will result in greater instability later tonight. Mosaic radar
imagery and lightning data showed an ongoing band of thunderstorms
extending from southeast NM into Far West TX, with this activity
located along the leading edge of strong ascent attendant to a
progressive, compact shortwave trough expected to reach central TX
by 12Z. Inverted-V thermal profiles per 00Z MAF sounding suggests
the greatest threat with these storms should be locally strong wind
gusts.

No changes have been made to the Slight risk area forecast for
central and east TX later this evening through early Monday morning.
As the strong forcing for ascent impinges on the moistening,
destabilizing air mass across central and east TX, thunderstorm
coverage is expected to increase in coverage with extension to the
north and south along a Pacific cold front. Large hail and damaging
wind will be the primary threat with the initial increase in storm
intensity and coverage, while a tornado threat will become an added
threat later tonight as activity encounters a strengthening
southerly low-level jet.

[DoctorMu]

GFS, GEM, TWC had winter precip next Saturday stretching across the South. From Alabama through North Carolina with the greatest chance. GFS runs it a bit north with TN and NC bullseye. GEM gives parts of Texas a taste on wintry stuff, and colder in SE Texas.

[DoctorMu]

GEFS Ensemble still running cold.

[srainhoutx]

First Severe Thunderstorm Watch of the New Year issued for portions of North, Central and SE Texas until 10:00AM