MontgomeryCoWx wrote:If IAH will be hovering around Freezing, you can bet my area of Montgomery County will be 4-7 degrees colder. I may not be driving into the city on Friday.
I'm S Montgomery County but it would probably be colder than Bush - oh, please let there be a "snow day!" I could use a day off from work - being the newbie I don't have time off till March!
Granted this is a long way out in time for the 15Z SREF ensemble individual members, but you can see that even the shorter range meso guidance is suggesting wintry weather may well be a possibility across our Region.
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HGX has updated their afternoon AFD. I suspect further changes will be forthcoming as we get closer to the Thursday time frame.
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
311 PM CST MON JAN 20 2014
.DISCUSSION...
WITH A AMPLIFIED FLOW PATTERN DUE TO A RIDGE UP THE PACIFIC COAST
AND THE DEEP LOW OVER AND NORTH OF THE GREAT LAKES...A COLD
AIRMASS WILL SINK INTO TEXAS LATER THIS WEEK. THINGS MAY GET
INTERESTING THURSDAY NIGHT INTO FRIDAY AS MOISTURE ASSOCIATED WITH
A COASTAL SURFACE TROUGH AND SHORTWAVE TROUGH ALOFT INTERACT WITH
THE COLD AIRMASS SINKING INTO THE AREA.
FOR THE SHORT TERM...A COLD FRONT WILL MOVE THROUGH SE TX TONIGHT.
MOISTURE POOLING AHEAD OF THE FRONT WILL LEAD TO AT LEAST PATCHY
FOG FORMATION WITH AREAS OF FOG MOST LIKELY FROM ABOUT THE
INTERSTATE 10 CORRIDOR SOUTHWARD TO THE COAST. THE 12Z MODELS KEEP
ANY RAIN DEVELOPMENT OFF TO THE EAST AND SOUTH...MAINLY OVER THE
COASTAL WATERS. BREEZY CONDITIONS ARE EXPECTED TO DEVELOP BEHIND
THE FRONT AND A WIND ADVISORY MAY BE NEEDED TUESDAY MORNING NEAR
THE COAST. THE WINDS SHOULD DIMINISH TUESDAY AFTERNOON. WIND
DIRECTION WILL THEN BECOME ONSHORE LATE TUESDAY NIGHT INTO
WEDNESDAY.
FOR THE LATTER HALF OF THE WEEK...A COLDER AIRMASS WILL THEN SINK
SOUTHWARD THROUGH THE PLAINS TOWARD TEXAS WEDNESDAY NIGHT INTO
THURSDAY NIGHT. AS IT DOES SO... THE GFS AND ECMWF HAVE BEEN
CONSISTENT WITH DEVELOPING AN AREA OF RAIN DUE TO ISENTROPIC LIFT
AND SHORTWAVE TROUGHS MOVING EASTWARD ACROSS THE STATE. BOTH THE
GFS AND ECMWF MOVE THE BEST RAIN CHANCES INLAND THURSDAY MORNING
AND AFTERNOON. BOTH MODELS THEN BEGIN TO DIFFER ON THE ENDING OF
THE PRECIPITATION THURSDAY NIGHT. AS THE PRECIPITATION
ENDS...TEMPERATURES WILL FALL TO BELOW FREEZING. FELT THAT BEFORE
IT ENDS...A WINTRY MIX IS POSSIBLE BETWEEN MIDNIGHT THURSDAY
NIGHT THROUGH LATE MORNING FRIDAY. OVERNIGHT LOW TEMPERATURES BY
EARLY FRIDAY MORNING ARE NOW LOOKING TO FALL INTO THE MID AND
UPPER 20S OVER MOST OF THE INLAND AREAS AND NEAR FREEZING ALONG
THE IMMEDIATE COAST. A SECOND NIGHT OF FREEZING TEMPERATURES IS
POSSIBLE FRIDAY NIGHT...ALTHOUGH BOTH MODELS DIFFER ON HOW LONG
THE AIRMASS WILL LINGER OVER THE AREA. IN ANY EVENT...THE GFS AND
ECMWF BRING A 1040 MB SURFACE LOW INTO THE AREA ON FRIDAY AND
TEMPERATURES THAT DAY MAY STRUGGLE TO REACH TO AROUND 40.
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What the forecaster meant to type was a 1040mb Arctic High Pressure Cell, not a surface low. Remember a High is like a mountain and a low is like a valley. High pressure has winds in a clockwise fashion that funnels air into the counter clockwise flow of a surface low. That said even upper lows which are about 20 to 30K feet up in the atmosphere do have a counter clockwise flow in the upper levels which in this case is why winds above the surface will be from the SW to W with that upper air disturbance and other embedded waves of upper low pressure riding across Texas creating lift, or over running precip and warmer air aloft or a warm nose. That is why freezing rain or sleet is the likely outcome for this potential event -vs- snow where the entire column is well below freezing. Surface winds will be brisk out of the N to NE depending on where and if a Coastal low/trough forms down near Brownsville.
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Ed Mahmoud wrote:I was looking for my blizzard of 1978. BTW, storms have much stronger pressure gradient and winds, than high pressure centers do.
This is the Midwest blizzard of 1978
The Great Blizzard of 1978, also known as the Cleveland Superbomb,[1] was a historic winter storm that struck the Ohio Valley and Great Lakes from Wednesday, January 25 through Friday, January 27, 1978. The 28.28 inches (958 millibars) barometric pressure measurement recorded in Cleveland, Ohio was the lowest non-tropical atmospheric pressure ever recorded in the mainland United States until the Upper Midwest Storm of October 26, 2010 (28.20" measured at 5:13PM CDT at Bigfork Municipal Airport, Bigfork, MN). The lowest central pressure for the 1978 blizzard was 28.05" (953 mb) measured in southern Ontario a few hours after the aforementioned record in Cleveland.[2] On rare occasions, extra-tropical cyclones with central pressures below 28 inches of mercury or about 95 kPa (950 mb) have been recorded in Wiscasset, Maine (27.9") and Newfoundland (27.76").[3]
32.01, in Siberia, is apparently the record. 1084 mb.
Cat 5 hurricanes can get below 900 mb. 953 mb was ballpark Ike, but a hurricane is a more concentrated low pressure, and will have higher winds over a smaller area.
Ed, I grew up in northeastern Ohio and experienced this blizzard first hand. It is one of those weather events that left an indelible memory. Very rarely have I witnessed the winter fury of Mother Nature like I did during that blizzard. It was absolutely amazing to live through.
Last edited by Portastorm on Mon Jan 20, 2014 4:45 pm, edited 2 times in total.
Powerful arctic cold front will arrive after mid week with some potential for wintery precipitation.
It does not get much better than this in mid-January…current afternoon temperatures at 300pm range from 80 at Victoria to 76 at BUSH IAH and 79 at Brenham. As is usually the case when it gets this warm in January cold air is not far behind and this week will be no different.
Upper air pattern is currently undergoing amplification along the US west coast with large scale ridging building into Alaska and the downstream trough located over the Midwest into NE US. A shot of cold air will pass across the region tonight into Tuesday with highs on Tuesday running 15-20 degrees colder than today (55-60) versus (75-80). Will see gusty NW winds on Tuesday along with lower RH so fire danger will be elevated. Cold Wednesday morning with lows in the upper 20’s and lower 30’s across the region rebounding into the mid 60’s by afternoon with SSW winds.
Thursday-Friday:
Forecast challenges are plenty in this period as a strong arctic air mass plows down the plains into TX and an upper level storm system then moves across the state with the cold arctic dome in place bringing P-type questions into the forecast. Arctic boundary should plow southward on Wednesday and push off the TX coast on Thursday with little appearing to slow the boundary or prevent the cold air from penetrating southward. Latest model guidance appears to be trending colder with the front as is common with shallow and fast moving arctic boundaries. Temperatures will fall rapidly on Thursday with the passage of the boundary and onset of cold air advection off the plains. Highs near 60 prior to the front will fall into the 40’s by late afternoon under gusty NW winds…and then into the 30’s and possibly 20’s by Friday morning.
While the cold air is filtering southward and upper level trough will be approaching the state from the WSW which will help induce a coastal surface trough slinging moisture northward over the cold dome. There will be a battle as to how much moisture can work northward against the southward moving dry air and what will the temperatures profile look like if and when the northward moving moisture wins out and the air mass over the area is able to produce precipitation.
Current thinking is that moisture may be just enough along with favorable lift to produce some amount of precipitation when the air mass at the surface is at or below freezing. Current forecast soundings support a mixture of sleet and freezing rain. Of course the position of the 32F line at the surface becomes very critical is determining what surface impacts of falling sleet or rain would have. Below 32F would possibly result in some accumulation of ice (freezing rain) or sleet and above 32 would result in sleet melting or just plain rain. Current indications suggest most of the area except the immediate coast could be at or below 32F by Friday morning. Good news is that currently the precipitation amounts look fairly light (below .05 of an inch)…but as we saw back in early December even .01 of an inch of freezing drizzle can cause some big problems on bridges. Given thick cloud cover and cold air advection think temperatures will go nowhere on Friday with a very small range between lows and highs and most likely temperatures hovering in the low to mid 30’s all day.
As with all winter weather episodes in this area the uncertainty is large especially at this range and will probably not get much better until about 24-36 hours before the onset of the event (late Wednesday into Thursday AM).
GFS model brings more precipitation into the area on Saturday again with very cold surface temperatures in place especially in the morning however other guidance is not as wet and think the GFS may be overdoing the rainfall. Still looks cold with highs on Saturday possibly only in the 40’s if it stays cloudy….50’s if the sun is able to break through.
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Very interesting days ahead. Still early yet. I know Wxman 57 said he would wait until (Correct me if I am wrong) 12Z Thursday models before having confidence in this event..but it is looking interesting from this novice's eyes...
Thursday A 50 percent chance of rain. Cloudy, with a high near 53. Breezy.
Thursday Night A chance of rain before 1am, then a slight chance of sprinkles, freezing rain, and sleet between 1am and 5am, then a slight chance of freezing rain and sleet after 5am. Cloudy, with a low around 29. Chance of precipitation is 30%.
Friday A chance of rain, freezing rain, and sleet. Cloudy, with a high near 42. Chance of precipitation is 30%.
Friday Night Mostly cloudy, with a low around 28.
Not ready to jump onboard yet however this is the time of year we are most likely to get Winter precip. For now I will model watch and read the AFDs. Perhaps Wednesday evening we will have a better idea of what will unfold Thursday night into Friday morning.
