December: New Years Eve Outlook

[tireman4]

Late Afternoon/Evening HGX AFD:

FXUS64 KHGX 042351
AFDHGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
551 PM CST WED DEC 4 2013

.DISCUSSION...
SEE THE 00Z AVIATION DISCUSSION BELOW.

40

&&

.AVIATION...
THE COLD FRONT WAS PUSHING SOUTH OF THE RED RIVER VALLEY LATE THIS
AFTERNOON. EXPECT SURFACE MOISTURE POOLING AHEAD OF THE FRONT AS
IT SLOWLY MOVES SOUTHWARD. MODEL FORECAST SOUNDINGS SHOW THAT IFR
TO MVFR CEILINGS WILL DEVELOP OVER MOST OF THE INLAND SITES BY
LATE THIS EVENING. SEA FOG WAS ALREADY OCCURRING OVER THE
NEARSHORE GULF WATERS AND BAYS. EXPECT THE SEA FOG TO LOWER
CONDITIONS AT KGLS TO VLIFR BY AROUND 02Z. THE FOG WILL LIKELY
PUSH INLAND OVER KLBX SHORTLY AFTER 06Z. WILL UPDATE IF THE FOG
PUSHES INLAND FASTER. THE FOG MAY ALSO AFFECT KHOU...AND THE BEST
GUIDANCE SUGGESTS BETWEEN 05Z AND 08Z. DO NOT EXPECT THE FOG TO
PUSH INLAND TO KIAH. HOWEVER...THAT SAID...CONFIDENCE IN THE FOG
FORECAST IS LOW AND WILL SEE HOW THE TRENDS GO OVER THE NEXT FEW
HOURS AND UPDATE IF NEEDED. EXPECT IFR CEILINGS AHEAD OF THE FRONT
AND THESE MAY LOWER TO LIFR IF THE GUIDANCE PANS OUT. MODEL
SOUNDINGS INDICATE MVFR CONDITIONS BEHIND THE FRONT.

40
http://forecast.weather.gov/product.php ... glossary=1

[cperk]

Just looked at the forecast for my area.We will be in the 40's for highs the entire 7 day forecast.

[Katdaddy]

Strong cold to push into SE TX tomorrow morning and across Houston Metro around noon time with temps in the 40s by the evening. Rain will accompany the front with a few thunderstorms. Winter precip is still possible along and N of a Brenham to Conroe to Livingston line per Houston-Galveston NWS. Houston Metro and points S look to have only a nasty cold rain. Be ready for a dramatic weather change tomorrow. Glad I got the Christmas lights up this evening.

[srainhoutx]

Evening Update from Jeff:

Arctic boundary moving southward this evening. Currently Amarillo is at 23 with Austin at 62. Boundary not surprisingly running a bit quicker than expected as is so common with these shallow dense cold air masses.

Will already have the boundary into our NW counties by sunrise and metro Houston by midday and to the coast by mid afternoon or about 3-5 hours faster than expected this morning. This will result in colder conditions on Thursday afternoon with widespread 40’s overtaking the area by sunset.

Other issue continues to be dense sea fog over the coastal areas and Gulf waters/bays as warm moist air flows over the cool shelf waters. Galveston has been bouncing around 1 mile visibility most of the afternoon and evening and expect some of this fog to spread inland over the next few hours possibly reaching US 59 SW of Houston and I-10 east of Houston.

Last issue is freezing rain and ice potential for parts of the area starting Friday evening and continuing into Sunday. Models have come in colder today with low temperatures now expected to fall into the upper 20’s over our northern counties Saturday morning and just barely get above freezing on Saturday in those areas. This supports freezing rain potential into our area starting Friday evening from College Station to Huntsville and possibly as far south as Brenham to Conroe by Saturday morning. Model QPF amounts look to be on the light side in the range of .01 to .05 of an inch and this would mainly be on elevated surfaces, but it does not cause much to result in slick bridges…in fact freezing drizzle is usually the worse type of freezing precipitation as is produces a very thin layer of ice which almost appears dry.  

Things could get a little more interesting Saturday night with the freezing line further south in the area and slightly better rainfall production suggesting more potential for accumulation especially across our northern counties.

Note:

Winter Storm and Ice Storm Warnings have been issued for N and NE TX starting late Thursday for significant accumulations of ice (.25-.50 of an inch). This will have major impacts on surface travel N or our region starting early Friday and potential for significant disruption of power and heavy vegetation damage. SE TX will be on the southern edge of the more significant ice accumulation.

[cristina6871]

I but a novice that likes to read this blog....especially this time of year. I was just looking at some childhood pics of the winter of 73 - I was but a toddler then, but there's a picture in my mom's arms and the snow is like an inch or two deep! I would love to have that again. Bring on the cold! Could it get colder than they are predicting?

[skidog40]

With this cold front there is no middle ground like the 40's. its all or nothing if we get 40's it touches Galveston and doesn't move. If this front moves through how doesn't it reach the 20's at night. This front has a lot of cold air behind it and to say it doesn't freeze, it obviously stalls out.

[TxJohn]

With this cold front there is no middle ground like the 40's. its all or nothing if we get 40's it touches Galveston and doesn't move. If this front moves through how doesn't it reach the 20's at night. This front has a lot of cold air behind it and to say it doesn't freeze, it obviously stalls out.

Yeah I was wondering the same thing.....it's packing a punch. It seems like it should be in the 20s here. Abc does have a low of 28 on Tuesday and 29 on Wednesday for Houston next week though. But they're the only ones with 20s so far.

[Andrew]

With this cold front there is no middle ground like the 40's. its all or nothing if we get 40's it touches Galveston and doesn't move. If this front moves through how doesn't it reach the 20's at night. This front has a lot of cold air behind it and to say it doesn't freeze, it obviously stalls out.

Yeah I was wondering the same thing.....it's packing a punch. It seems like it should be in the 20s here. Abc does have a low of 28 on Tuesday and 29 on Wednesday for Houston next week though. But they're the only ones with 20s so far.

We have to remember there are multiple factors effecting temperatures in this situation. The first and most influential factors is the gradient that is associated with this front. The gradient is pretty steep for an event like this meaning places to the north are going to be much colder than places to the south. For example College Station could get down to the mid to upper 20's Saturday morning (depending on QPF and P-type) while Houston only gets to the mid 30's. Then you look at Dallas and they could get down to the mid teens which shows there is a pretty nice pressure gradient associated with this front. Next cloud cover and precipitation quantity/ type will also help to determine temperatures. More cloud cover will result in lower high temps but higher low temps. The closer you get to the coast the more abundant this cloud cover will become especially if a coastal low develops. Finally if you get wintry precipitation this type of precipitation can be "heat absorbing". If you get melting or evaporation that will take heat out of the atmosphere and as a result cool temperatures. Evaporation is much more effective but melting of ice can also help. With this situation there will be different p-types and where ice sets-up could impact the temperatures for that region. All these factors combined help create these weird differences in temperatures you are speaking of. Plus on top of everything else this isn't even the main event yet ( I believe). The cold spell this week is more of a result of the Pacific heights pushing colder air south this way. Early next week we could see a McFarland signature appear where the 500mb synoptic allow for some very cold air to advect straight from the polar region .With these type of events the Jet becomes crucial in bringing that air SW straight towards the Texas area. Some of the stronger and more memorable cold snaps have been as a result of these type of events. That is why I feel like next week (Tuesday or so) we could see much colder temps across the whole area. As of now i feel like the models are having a tough time picking up on how cold things could actually get.

[Belmer]

Local meteorologist up here in OKC said this is the coldest stretch of arctic weather since December of 1983. I know that year has been mentioned a few times. The lowest temperature I have ever experienced was 18 degrees when Houston had that arctic outbreak back a couple years ago (2011 I want to say). The high forecasted here in Norman on Saturday is 18 with a low in the negatives by Tuesday morning. So I'll be looking forward to that... ha

Anyway, hope something magical happens down in Houston area this week. Many got caught off guard, even local mets during Thanksgiving week when many saw snow flurries, even though nothing accumulated. Wouldn't rule anything like that out again for this week. Mother Nature, especially Arctic outbreaks have a mind of their own!

[srainhoutx]

Winter Weather Advisory issued for Metro Austin. It appears a Winter Weather Advisory may be hoisted for portions of SE Texas mainly N of I-10 later today. NWS Houston/Galveston mentioning that light freezing drizzle/light freezing rain may slip further S into Metro Houston before all the moisture moves out late on Sunday. The front has passed College Station with gusty NW winds of 30 MPH and temp fell from 70 F to 53 F.

[srainhoutx]

Morning Update from Jeff:

Powerful arctic cold front entering SE TX this morning.

Increasing potential for significant ice storm across N and NE TX Friday-Sunday with SE TX on the southern edge of the event

Arctic boundary has entered the area this morning with College Station now at 53 degrees and Houston at 72. Upstream observations are 37 at Dallas, 15 at Amarillo, and -10 at Denver. Front is making good southward progress and will be through the metro area before noon and offshore by mid afternoon. Temperatures will fall 20-25 degrees with the frontal passage and continue to cool quickly into the 40’s by afternoon possibly upper 30’s NW. Do not expect much rainfall with the front, but chances for rain will increase overnight into Friday.

Main portion of this forecast will be on the potential for freezing rain and freezing drizzle across the area Friday-Sunday and low temperatures next week.


1. Temperatures: Models continue to show slightly colder conditions as is usually the case with such shallow arctic air masses. This places near/sub-freezing surface temperatures across our NW counties as early as 300-400am Friday morning (College Station to Huntsville). Expect very little is any warming on Friday as cold air advection process continues to bring frigid air southward off the central plains and across extensive ice formation over N TX. May see temperatures hold steady in the 32-35 range all day Friday over our NW and N counties and in the upper 30’s to lower 40’s across the rest of the area. By Friday evening the freezing line will progress southward likely reaching a Hempstead to Conroe line overnight into Saturday morning. Highs on Saturday may stay very near freezing from Hempstead to Conroe northward. Saturday night into Sunday the freezing line moves southward again possibly reaching a line from Columbus to Tomball to The Woodlands. Many areas will fall into the 30’s tonight and not rise above 40 until maybe Sunday. Good news is that cloud cover will keep overnight lows in the upper 20’s NW to mid-upper 30’s coast.

2. Precipitation and Type: Forecast soundings show a classic overrunning situation with shallow cold air ranging anywhere from 900ft to nearly 2000ft deep across the region with a significant warm layer above that due to south winds riding up and over the surface cold dome. This supports a freezing rain profile with liquid rain falling out of the warm layer aloft and then freezing on contact forming a layer of ice. This will only work if the surface temperature is at or below freezing….otherwise it is all rain. The profiles do not support sleet or snow with such warm air aloft. In fact one item to keep in mind is that the rain drop will actually likely be slightly warmer than the surface air temperature due to its descent through such a warm layer aloft so even if the surface temperature is 32 it may be hard to get ice to form. Disturbances moving NE across the area will determine the best time periods for rainfall across the region…but expect amounts to be generally light.

Think there is at least a decent chance of freezing rain/drizzle over our NW counties as early as Friday and continuing into Sunday…this is mainly NW of a line from Brenham to Huntsville. Each night with the southward advance of the freezing line, the potential shifts SE for both Saturday and Sunday mornings and possibly includes the N and NW portions of Harris county, much of Montgomery County, Waller County, and portions of Austin County.

3. Ice Accumulations: Ice will only form if the air temperature is 32 or lower at the surface. Think the best rain chances will be from midnight tonight until about noon on Friday when most of the area should be above freezing. As temperatures fall to the freezing point, rainfall should be on the decrease in intensity mainly just light rain and drizzle. Accumulations of ice from Friday evening –Sunday morning of .01 to .05 of an inch will be possible NW of a line from Brenham to Conroe to Livingston and this will mainly be on elevated surfaces such as trees and power lines. Could see a few icy bridges in this area also especially by Sunday morning as the pavement cools over time. Further southward the threat is much more conditional as the rain must fall in the short window when the temperature may be near freezing which reduces accumulation. Any light ice accumulation north of a line from Columbus to Tomball to The Woodlands would be in the trace to .05 of an inch and mainly on Saturday morning for a few hours and again on Sunday morning.

4. Impacts: Do not see much if any issues with trees and power lines across the area…although those NW continues will have to be watched closely as accumulations of up to .10 of an inch could begin to cause some widely scattered outages and downed tree limbs. Ground temperatures are warm so it will take time for the air mass to cool the pavement to the freezing point allowing ice formation on elevated surfaces (bridges and overpasses). Do not think there will be any problems on Friday. By Saturday morning a few bridges could have some ice in the College Station to Huntsville area and then by Sunday morning north of a Brenham to Conroe line. Again we are talking very light amounts, but freezing drizzle is one of the worst types of winter weather as it produces a very thin layer of ice on the pavement that almost appears dry. Right now think Harris County will not have ice formation on bridges and overpasses, but it could be close on Sunday morning N and W.

Uncertainty: As with all winter weather events in this area, there is always a degree of uncertainty as the difference of 1 degree can make the difference between rain and ice. Determining the exact freezing line location at any given time is fairly difficult, yet that determines where the rain/ice line will be. This is a moving target at this point and even during the event.

Winter Storm Warning/Ice Storm Warning area (N and NE TX):

Across N into NE TX conditions will be much worse with a significant ice storm expected from late tonight-Sunday. Surface temperatures in the mid to upper 20’s with liquid rain falling and freezing on contact is about as bad as an ice setup you can get. Rainfall amounts in this region may reach 1.0-1.25 inches with ice accumulation of .25 to .50 of an inch resulting in widespread heavy ice formation on trees and power lines. Ice accumulation will be more than enough to down large tree limbs and power lines resulting in potential widespread and prolonged power outages. Travel even on surface streets will be difficult if not impossible. This will be a prolonged event with temperatures falling below freezing tonight and likely not rising above freezing until sometime toward the middle of next week.

Next Week Cold:

Secondary arctic surge will arrive into the region Monday. Models continue to advertise extremely cold air moving southward with the 32F line pushing toward the coast and the 0F line reaching toward the Red River. With skies likely clearing, the setup will be for bitter cold conditions by Tuesday morning. Could see hard freeze criteria (25 or lower for 3 hours) north of I-10 by Tuesday morning. This is still a ways out and there could be some changes to the amount of cold that moves southward, but with a good snow cover over the central plains and N TX covered in ice, this air mass will not moderate much. Something to keep an eye on as this would require pipes to be protected across our region.      

[MontgomeryCoWx]

WxBell is fantastic.

Looks like Montgomery, Waller, Walker, Grimes and Brazos could potentially see close to .1 inches of ice.

[unome]

http://www.wrh.noaa.gov/mesowest/gmap.php

it's here, grab your jacket on your way out the door...

[MontgomeryCoWx]

I just felt it drop 10 degrees at work here on the North Beltway. My house is 15 degrees colder than here.

[cristina6871]

question - the graphic chart Ed Mahmoud posted recently from weatherbell - the last picture shows the state all in white and snow in the bottom corner. What does that mean? Are we in for some snow? I am trying to learn how to read the charts.

[srainhoutx]

question - the graphic chart Ed Mahmoud posted recently from weatherbell - the last picture shows the state all in white and snow in the bottom corner. What does that mean? Are we in for some snow? I am trying to learn how to read the charts.

The bottom right snow map has the green shade where those graphics are 'predicting' snow. I will offer a word of caution when using these various graphics. They tend to be a generalization and may have large errors in the parameterization scheme, so 'buyer beware'. What I would offer everyone as we look at things the over next several days ids to expected changes. As we know from past experience, it does take much of a change...one way or the other to have dramatic effects on the sensible weather we can actually see at any given location. If temperatures end up being a bit colder than expected, icing becomes a problem on overpasses and elevated surfaces. If they end up warmer, just a cold and nasty rain. The front is passing through, so now we will just have to see what develops over the next 3-5 days as it does appear we will stay very chilly until sometime next week.

[srainhoutx]

Here is a snippet from NWS Brownsville from their morning Area Forecast Discussion. It shows very well just how widespread the Arctic air mass will reach S into the Rio Grande Valley.

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...EVOLUTION OF UPPER
AIR PATTERN REMAINS ON TRACK TO LOCK IN A COUPLE OF SURGES OF
ARCTIC AIR TO THE RIO GRANDE VALLEY. THE FIRST WILL ALREADY
THROUGH THE REGION FRIDAY NIGHT WITH THE NEXT SURGE ON MONDAY.
WINTER WEATHER HIGHLIGHT DURING THIS PERIOD WILL BE VERY LOW WIND
CHILLS...LIGHT FREEZE OVER THE RANCH LANDS AND A SMALL CHANCE OF
SOME SLEET MIXING IN WITH LIGHT RAIN SATURDAY ALSO ACROSS THE
RANCH LANDS.

COLD AIR ADVECTION TO PEAK SATURDAY WITH A STRENGTHENING LOW LEVEL
INVERSION. SOUTHERLY FLOW ABOVE THE INVERSION STRENGTHENS AS A
THE POSITIVELY TILTED UPPER TROUGH OVER THE ROCKIES DEEPENS. ISENTROPIC
LIFT MAXIMIZES SATURDAY WITH A CHANCE OF RAIN AND PREDOMINATE
DRIZZLE. POINT SOUNDINGS CONTINUE TO SHOW A SATURATED LAYER OF
AROUND 1500 FEET DEEP DIPPING BELOW FREEZING ACROSS THE NORTHERN
RANCHLANDS. THIS SUGGEST THAT A MIX OF SLEET WITH THE RAIN IS
POSSIBLE LATE FRIDAY NIGHT INTO SATURDAY MORNING. HAVE NOT
INDICATED THIS IN THE GRIDS JUST YET AND WILL WAIT ANOTHER PERIOD
OR TWO TO SEE HOW MUCH COLD DOES MAKE IT THIS FAR SOUTH. IN ANY
CASE SURFACE TEMPERATURES TO REMAIN ABOVE FREEZING WHICH WILL
ALLOW FOR ANY SLEET TO MELT RATHER QUICKLY ON CONTACT. OTHER WISE
WITH NO SUN AND THE LOW OVERCAST AND PRECIP TEMPERATURES WILL
STRUGGLE TO BREAK 40 DEGREES IN THE NORTH AND 45 AT THE COAST.
FINALLY WITH THE STRONG NORTH WINDS WIND CHILL ADVISORIES ARE
LOOKING MORE PROBABLE FOR FRIDAY NIGHT INTO SATURDAY MORNING.

A BRIEF REPRIEVE STILL IN ORDER SUNDAY AS THE NEXT SURGE TAKES
SHAPE OVER THE ROCKIES. SLOW IMPROVEMENT IN TEMPERATURES WITH MOST
OF DRIZZLE ENDING WITH EXCEPTION TO THE COASTAL AREAS. SECOND
FRONT TO MOVE THROUGH MONDAY LATE MORNING EARLY AFTERNOON.
PRESSURE GRADIENT TO STRENGTHEN AS 1039MB HIGH INTERACTS WITH
LOWER PRESSURE OFFSHORE. TEMPERATURES TO FALL DURING THE AFTERNOON
AS WINDS PICK UP BECOMING BLUSTERY. BOTH GFS/ECMWF INCREASE POPS
MONDAY WITH A STRONGER COASTAL LOW DEVELOPING. FORECAST HAS BEEN
ADJUSTED TO SHOW STRATIFORM RAIN DEVELOPING ALONG WITH DRIZZLE
ONCE AGAIN.

[Portastorm]

Temperatures dropped 30 degrees in just four hours here in the land of Bevo!

[srainhoutx]

Numerous reports coming in now from the Lubbock area of heavy icing on surface road ways making travel extremely dangerous. NWS Lubbock states that the models have under estimated the strength of the various disturbances heading toward Texas and they are re evaluating the situation at this time.

[srainhoutx]

Winter Storm Warning coming shortly for the Lubbock area.