January: Calmer Pattern To End The Month

[Heat Miser]

Appreciate that very informative post, Candy.

[tireman4]

Thank you so much Candy Cane. That was an amazing analysis.

[weatherag]

Blue star for Candy Cane.

[srainhoutx]

[Rip76]

"I think there *could* be a single troll who alternates between all caps weirdness and Chita Johnson stalking persona, and 'we're all going to die' from an hour 264 18Z GFS hurricane in the Gulf persona.

I could be wrong."

Brilliant



Great explanation CC.

[srainhoutx]

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
257 PM CST SUN JAN 26 2014

...WINTER STORM WATCH FOR TUESDAY...

.AN ARCTIC AIRMASS WILL SETTLE OVER THE AREA LATE MONDAY DROPPING
TEMPERATURES TO AROUND FREEZING TO WELL BELOW FREEZING TUESDAY
MORNING. AN UPPER LEVEL DISTURBANCE WILL MOVE TOWARD THE REGION
FROM THE SOUTHWEST HELPING TO INITIATE THE DEVELOPMENT OF
SNOW...FREEZING RAIN...AND SLEET. THIS WINTER PRECIPITATION SHOULD
CONTINUE THROUGHOUT THE DAY AND TAPER OFF FROM NORTHWEST TO
SOUTHEAST BY EVENING ALONG THE COAST. SIGNIFICANT ICING IS LIKELY
ACROSS THE REGION. SNOW FALL ACCUMULATIONS OF 1 TO 2 INCHES SHOULD
BE COMMON OVER THE NORTHERN HALF OF SOUTHEAST TEXAS WITH ISOLATED
HEAVIER AMOUNTS. TEMPERATURES SHOULD BOTTOM OUT WEDNESDAY MORNING
IN THE 20-25 DEGREE RANGE FROM INTERSTATE 10 NORTHWARD.
TEMPERATURES SHOULD RISE BACK ABOVE FREEZING AFTER NOON ON
WEDNESDAY.

TXZ163-164-176>179-195>200-210>214-226-227-235>238-270500-
/O.NEW.KHGX.WS.A.0002.140128T0900Z-140129T0600Z/
AUSTIN-BRAZORIA-BRAZOS-BURLESON-CHAMBERS-COLORADO-FORT BEND-
GALVESTON-GRIMES-HARRIS-HOUSTON-JACKSON-LIBERTY-MADISON-MATAGORDA-
MONTGOMERY-POLK-SAN JACINTO-TRINITY-WALKER-WALLER-WASHINGTON-
WHARTON-
INCLUDING THE CITIES OF...ALVIN...ANAHUAC...ANGLETON...BAY CITY...
BELLVILLE...BRENHAM...BROOKSHIRE...BRYAN...CALDWELL...CLEVELAND...
COLDSPRING...COLLEGE STATION...COLUMBUS...CONROE...CORRIGAN...
CROCKETT...DAYTON...EAGLE LAKE...EDNA...EL CAMPO...FREEPORT...
FRIENDSWOOD...GALVESTON...GROVETON...HEMPSTEAD...HOUSTON...
HUMBLE...HUNTSVILLE...KATY...LAKE JACKSON...LAKE SOMERVILLE...
LEAGUE CITY...LIBERTY...LIVINGSTON...MADISONVILLE...
MISSOURI CITY...MONT BELVIEU...NAVASOTA...ONALASKA...PALACIOS...
PASADENA...PEARLAND...PIERCE...PRAIRIE VIEW...RICHMOND...
ROSENBERG...SEALY...SHEPHERD...SUGAR LAND...TEXAS CITY...
THE WOODLANDS...TOMBALL...TRINITY...WEIMAR...WHARTON...WILLIS...
WINNIE
257 PM CST SUN JAN 26 2014

...WINTER STORM WATCH IN EFFECT FROM LATE MONDAY NIGHT THROUGH
TUESDAY EVENING...

THE NATIONAL WEATHER SERVICE IN HOUSTON/GALVESTON HAS ISSUED A
WINTER STORM WATCH...WHICH IS IN EFFECT FROM LATE MONDAY NIGHT
THROUGH TUESDAY EVENING.

* TIMING...SNOW AND SLEET WITH SOME PATCHY FREEZING RAIN WILL
DEVELOP AROUND COLLEGE STATION EARLY TUESDAY MORNING THEN EXPAND
EAST AND SOUTHEASTWARD ACROSS THE HUNTSVILLE AND CONROE AREAS
EVENTUALLY REACHING THE HOUSTON METROPLEX AROUND NOON. CLOSER TO
THE COAST FREEZING RAIN AND SLEET WILL BE THE MORE COMMON FORM
OF PRECIPITATION AND SHOULD DEVELOP AROUND 3 PM. THE
PRECIPITATION SHOULD TAPER OFF FROM NORTHWEST TO SOUTHEAST
DURING THE LATE AFTERNOON AND AROUND THE COAST BY 9 PM.

* IMPACTS...VERY COLD ROAD SURFACES WILL BE CONDUCIVE TO FREEZING
RAIN AND SNOW ACCUMULATIONS. SURFACE ROADS ARE LIKELY TO BE
IMPACTED IN ADDITION TO ELEVATED ROADWAYS. ELEVATED ROADWAYS MAY
BE ENTIRELY IMPASSABLE. TRAVEL MAY BE SEVERELY LIMITED.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WATCH MEANS THERE IS A POTENTIAL FOR SIGNIFICANT
SNOW...SLEET...OR ICE ACCUMULATIONS THAT MAY IMPACT TRAVEL.
CONTINUE TO MONITOR THE LATEST FORECASTS.

[cperk]

candy cane do you remember feb 2011 and how the models burned us? since you're a pro met i would like your thoughts. i remember you posting on the forum the night of that event. and it became obvious the models had screwed us., remember,no negativity txjohn. lets not even think about dry air

Well it's important to remember that a forecast model is only a tool that is used in weather prediction. However often times we have turned the model into the exact forecast. I think that's the first problem. As we saw last Friday, just because the model indicates something doesn't necessarily means it plays out that way. We saw heavy snow bands set up much further inland than anybody predicted due to the influx of ''dry air.''

It's also important to remember that each winter storm is its own beast and comparing two storms may or may not be a fair comparison. In 2011, our in-house computer model (RPM) at KPRC showed an ice event. Not snow. The microcast models that the other stations were using were indicating snow which clearly wasn't right. Houston in the 2011 event sat in a unique location. The dendritic layer (850 mb--snow making layer) was below 0c at Lake Charles. The sounding at Corpus was above freezing at 850. Intuitively it only made sense that if Lake Charles was below freezing and Corpus was above that the temp at 850 in Houston was probably right at 0c. It wasn't. We had a more pronounced warm nose and therefore we got ice instead of snow.

This event, the air is clearly colder than Friday's event. Therefore almost all precip should fall frozen and not wait on the rain to wet bulb us down to freezing. The second thing is this is a much more pronounced disturbance. When looking at a QPF of .65 inches, that signals to me right away that this could be a pretty significant event. Keep in mind however that a significant event is 2 inches in Houston.

It should be noted though that if IAH were to pick up 4 inches of snow, it would be the heaviest snowfall since the 1950s in Houston and while currently not in the forecast, it wouldn't shock me a bit to see somebody end up with over 4 inches...and that is being conservative.

This is assuming all variables remain as they are now---which clearly they won't. I think it's worth watching and definitely worth issuing a Winter Storm Watch due to the high impacts of winter weather on our area.

Great analysis Candy Cane thanks.

[srainhoutx]

NWS New Orleans issues Winter Storm Watch

[Andrew]

Just a general PSA:

Over the next couple of days, the board will be monitored for extreme posts that include any political posts or extreme exaggeration. Remember everyone this board is here for the discussion of factual information and predictions. Many people come on here looking for support on what their area could receive. Lets keep up the quality of the board and leave the other nonsense out of here.

Thanks
-Moderating team

[TexasMetBlake]

I've asked a couple of other meteorologists and nobody can remember the last time we had two winter storm watches out for the Houston area in a 4 day period. Maybe the 70s? Either way, pretty unprecedented.

[SusieinLP]

Ok, now that the Winter Storm Watxh is here.... I'm curious to see how school districts will handle this storm. It appears this will be a daytime event on Tuesday with conditions deteriorating as day goes on. Do they close early or cancel ? And then there is Wednesday to consider. How fast will ice melt, if indeed this all plays out as described in forecasts?

[Rip76]

I've asked a couple of other meteorologists and nobody can remember the last time we had two winter storm watches out for the Houston area in a 4 day period. Maybe the 70s? Either way, pretty unprecedented.

I cannot remember a time like this either.

[srainhoutx]

Update from Jeff:

NWS will be issuing a Winter Storm Watch effective from 300am Tuesday until midnight Wednesday for all SE TX counties.



High impact winter storm appears likely Tuesday and Wednesday.



Discussion:
Forecast models have come into much better agreement today with increasing threat of accumulating ice and snow across all of SE TX starting early Tuesday and lasting into early Wednesday. Nearly all global models agree that moisture and cold air will be in place at the same time to produce a period of mixed precipitation across nearly the entire area. Still some uncertainty in when exact locations fall to and below freezing on Tuesday which will dictate when exactly accumulations begin.

Temperatures:
Arctic front will push off the TX coast Monday afternoon with temperatures falling into the 30’s and 40’s for most areas by sunset. Freezing line will reach the northern counties between 1000pm and midnight and progress to the I-10 corridor by 300-400am and close to the coast by 800-1000am Tuesday. Do not expect much if any temperature recovery on Tuesday as increasing precipitation along with ongoing cold air advection will result in evaporative cooling of the air column and surface temperature. Think any amount of potential warm up will be under-cut by this process. Very cold Tuesday night into Wednesday morning with lows falling into the mid 20’s at many locations. Wednesday warm up will be slow and is highly dependent on the degree of cloud cover and when clouds begin to break. Way too soon to attempt to give any kind of feeling on when certain areas will rise back above freezing on Wednesday, but it will likely be after noon and if clouds do not thin and with ice/snow on the ground it may not happen at all.



P-type:
Going to be a mess trying to time P-types and changes at locations. Air mass is colder than the last event which would support more snow, but pesky warm layer is seen in soundings which has burned us before in this area (Feb 2011) keeping P-type more in the freezing rain category. Models want to produce more snow, but I am just not completely sold on it yet. Best P-type attempt and changeover right now:

North of Brenham to Conroe to Cleveland: sleet and snow starting prior to 600am Tuesday and changing to all snow during the day.

North of I-10: freezing rain and sleet starting around 900-1100am changing to sleet and snow in the late afternoon.

Coast to I-10: freezing rain starting around noon. Freezing rain mixing with sleet by mid afternoon. Possible change to snow after 800pm Tuesday.

There is going to be changes with these P-types over the next 24 hours and this will affect accumulation amounts.



Accumulation:
Since the air mass and surface temperatures look colder with this event than the last…expect much more efficient ice/snow accumulation with much less melting. Appears most of the area will be at or below freezing at the onset of the precipitation which will help increase accumulation over last week. With that said…mixed phase precipitation is extremely hard to get good accumulation amounts on. Will keep things fairly general at this point

Freezing rain and ice accumulations of .10 to .20 across the area….mainly south of I-10

Snow accumulations of 2-4 inches north of Hwy 105…likely little freezing rain in this area

Snow accumulations of 1-2 inches all other areas on top of possible ice accumulation

Another aspect to keep in mind is the potential for meso scale snow banding which has been seen in past events (Dec 2004, Dec 2008, and Dec 2009) in which favorable lift can focus a period of moderate to heavy snow across certain locations. This is very much like trying to forecast training heavy rainfall in the summer months and is nearly impossible to determine until it is underway but can result in very quick and more significant accumulations.

Impacts:

Big impact is going to be onset of precipitation during the daytime hours versus overnight/morning. For the most part Tuesday morning 400-800am looks dry, with precipitation breaking out during the day. This will likely result in a fairly uneventful morning rush hour with conditions going quickly downhill in the afternoon hours and a potentially very difficult evening rush hour.

A note to be said about snow…most people think it is easier to drive on snow…and this is usually true, but only if the ground below the snow is at or below 32…which here is not the case compared to up north. Ground and roadway surface temperatures will be hovering in the 31-35 range which will melt falling snow into a layer of ice over top the pavement which then becomes snow covered. This produces extremely hazardous driving conditions and is very common in the southern states during snow events.

Given the colder surface air temperatures, may be looking at icing and accumulation on surface streets and just not bridges/overpasses. A layer of ice can form on surface streets even if the ground is above freezing due to surface cold air. Typically this will happen when temperatures are in the mid to upper 20’s for a period of time. This happened in Dallas in early December with air temperatures in the mid 20’s yet ground temperatures were in the mid 30’s.

Freezing rain looks likely especially south of I-10 to start the event and then it becomes important how quickly precipitation changes over to sleet or snow or some combination. Do not think accumulations will be enough to cause widespread disruption of power, but if the change was slower or does not happen amounts could be very near the .25 of an inch threshold to start to cause power problems. Other comment is that it is going to be colder, so almost all the freezing rain is going to glaze into ice very effectively with little moisture lost….this is a big difference from last week when the first .10-.20 of liquid was lost due to surface temperatures being above freezing..

[Heat Miser]

I've asked a couple of other meteorologists and nobody can remember the last time we had two winter storm watches out for the Houston area in a 4 day period. Maybe the 70s? Either way, pretty unprecedented.

Sad thing is that I remember playing in that snow in the 70's. One thing I can say about our events down here.......they just never lasted as long as I wanted. Always left me wanting more only to have to wait years for the possibility to arise again.
This is unique time.

[Baseballdude2915]

Stepping on Ptarmigan's toes here but I was looking for snowfall info for Pensacola, since they are record setting territory if models verify and found this nice little article on historical snow systems in the S/SE US. Crazy that this system might join the list of all time greats, especially for AL/MS/FL.

http://www.wunderground.com/blog/weathe ... erspective

[srainhoutx]

NWS Lake Charles to issue Winter Storm Watch shortly

[srainhoutx]

NWS San Antonio/Austin will monitor as they are expecting a lower impact event. They will issue Advisories/Watch or Warning if conditions become necessary.

[seanatsk]

Great I leave Houston for 2 weeks and we get two winter weather events...I saw a little bit of snow here in Atlanta the other day but it didn't even stick

[Ptarmigan]

I've asked a couple of other meteorologists and nobody can remember the last time we had two winter storm watches out for the Houston area in a 4 day period. Maybe the 70s? Either way, pretty unprecedented.

The closest I am thinking are 1973 and 1985. January 1985 had three ice storms, while February 1973 had two snow events a week apart. Prior to it, there was an ice storm. I can imagine that happening in the 1880s and 1890s.

Winter of 1972-73 was El Nino while 1984-85 was La Nina.

http://www.wxresearch.com/snowhou.htm
http://www.wxresearch.com/almanac/houice.htm

[Ptarmigan]

Stepping on Ptarmigan's toes here but I was looking for snowfall info for Pensacola, since they are record setting territory if models verify and found this nice little article on historical snow systems in the S/SE US. Crazy that this system might join the list of all time greats, especially for AL/MS/FL.

http://www.wunderground.com/blog/weathe ... erspective

The same system in 1973 gave Houston snow on February 9-10, 1973.