Forecasters struggle again with Tues/Weds storm
Here we go again. The weather story all winter, it seems, has been one of forecasters and their computer models struggling to get a grip on a repeated pattern of complex storm systems.
This weekend seems to be no exception. Once again, the supercomputers are wrestling with a combination of a clipper-like storm moving out of the Northwest, expected to cross the country's mid-section, converge on a southern low that will cross the South and emerge off the mid-Atlantic coast early next week.
Where will these disturbances go, exactly? When will they get there? Will the systems merge in just the right spot to dump snow? Will one pass to our north or west and bring rain and sleet? Or, will they both veer away and leave us in the bubble again?
AccuWeather.com is already sounding pretty aggressive on this one, although they don't seem to have figured out the storm tracks, either. The NOAA Climate Prediction Center has us in the "Heavy Snow" zone on their forecast map. But the "Heavy Rain" zone is nearby. Foot's Forecast lays out two scenarios. Here's the official forecast from Sterling.
Today's NWS forecast discussion from Sterling contains an unusual admission of the difficulties the folks at Sterling have been having this winter. I present it below, edited only to expand abbreviations:
"MOST OF THE LONG TERM FORECAST WAS SPENT LOOKING AT THE POTENTIAL
COASTAL STORM TUES INTO WED. THIS WINTER HAS FEATURED MANY COMPLEX
STORM SYSTEMS IN THE MEDIUM RANGE THAT HAD A POTENTIAL TO IMPACT
THE AREA. OPERATIONAL MODEL GUIDANCE HAS HANDLED THESE PHASING
SYSTEMS POORLY SO FAR THIS WINTER...RESULTING IN LOWER THAN NORMAL
MODEL SKILL AND FORECAST CONFIDENCE MORE THAN A COUPLE DAYS OUT.
"THE UPCOMING TUE-WED SYSTEM WILL BE NO EXCEPTION. WHILE CONFIDENCE
IS HIGH THAT A COASTAL LOW WILL DEVELOP NEAR THE SOUTHEASTERN
COAST...THE EXACT TRACK OF THE LOW IS HIGHLY UNCERTAIN. THE TRACK
OF THE LOW /WHICH DEPENDS ON THE TIMING AND OCCURRENCE OF PHASING
BETWEEN SOUTHERN AND NORTHERN STREAM DISTURBANCES/ AND THE EASTWARD PROGRESSION OF THE SURFACE HIGH MOVING NORTHEAST OF NEW ENGLAND WILL BE CRITICAL
IN DETERMINING THE PRECIP AMOUNTS AND THE PRECIP TYPE.
"IT IS TOO EARLY AT THE MOMENT TO NAIL DOWN THE SPECIFICS AS THE PRIMARY NORTHERN STREAM ENERGY ASSOCIATED WITH THE UPCOMING STORM IS STILL NEAR THE GULF OF
ALASKA. THE MODELS HOPEFULLY WILL CAPTURE THIS ENERGY BETTER ONCE
IT MOVES INTO WESTERN CANADA TONIGHT INTO SUNDAY.
"AS STATED ABOVE...THE WIDE RANGE OF MODEL SOLUTIONS PROVIDES A WIDE
RANGE OF POSSIBLE IMPACTS FROM THIS SYSTEM. THE WESTERN-TRACK SOLUTIONS
SUCH AS THE 12Z NAM [MODEL] /TOWARD THE END OF ITS RUN/ AND GEM [MODEL] HAVE A
TRACK OF THE LOW CLOSER TO THE APPALACHIAN SPINE THAT WOULD RESULT
IN A MOSTLY RAIN EVENT.
"THE EASTERN-MOST SOLUTION THAT THE 12Z GFS [MODEL RUN] PORTRAYS HAS A TRACK WELL OFF THE COAST...SAVING THE AREA FROM A DIRECT IMPACT. THE MEAN OF THE 12Z GFS ENSEMBLE MEMBERS AND 12Z ECMWF SHOWS A SOLUTION SLIGHTLY WEST OF THE 12Z OPERATIONAL GFS RUN...WHICH WOULD LEAD TO THE BIGGEST IMPACT WITH MORE SNOW THAN
RAIN. COMPARED TO YESTERDAY...
"THERE IS A EASTWARD TREND IN THE TRACK OF THE LOW. GIVEN LATEST TRENDS AND SPREAD IN GUIDANCE...DO NOT FEEL THAT INCREASING [PRECIPITATION PROBABILITIES] IS WARRANTED. HAVE ALSO TRIED TO DETERMINE MOST LIKELY TIME PERIOD FOR PRECIP WITH THIS SYSTEM...WHICH NOW APPEARS TO BE LATE TUES INTO WED.
"WHAT HAPPENS AFTER THIS STORM PULLS AWAY FROM THE AREA WILL DEPEND
ON PRIOR EVENTS WITH THE MIDWEEK SYSTEM. IT DOES APPEAR THAT THE PACIFIC
NORTHWEST JET STREAM REMAINS ACTIVE EVEN INTO THE END OF NEXT WEEK...WITH
RIDGING OVER THE WEST COAST AND TROUGHING OVER THE EASTERN CONTINENTAL US HOLDING
FIRM. THIS PATTERN WILL FAVOR NEAR- TO BELOW-NORMAL TEMPERATURES
CONTINUING INTO THE WEEKEND."
Comments
I have no idea what this means. I need the simple version...lol
FR: That's the weather geek version. Bottom line is they're looking at the same complex, hard-to-predict set of weather systems for the coming week that they have had to contend with for most of this winter's storms. They have had little success in predicting it accurately days in advance before, and see no good prospects for improving their performance this time.
Posted by: Michelle Brown | January 22, 2011 9:27 PM
Why is it this winter no one can seem to read the radar? I am afraid what is going to happen is poor reading of the radar is going to get us all caught in a blizzard. Children will be in school and people will be at work What a mess that will be. Then you will really have some pissed off people on your hands.
Posted by: Annie Hunt | January 23, 2011 12:52 AM
They ought to be commended for their honesty. It is much better to admit the complexity of the task than to guess one way or another on something that affects so many.
Posted by: Chad Cos | January 23, 2011 2:03 AM
Frank,
Thanks for the explanation. That's what I thought it said, but wasn't sure. I'm sure there were many others who also were 'not in the dark', but in the (what shall we call it) - 'semi-shade'?
Posted by: Mike | January 23, 2011 2:39 AM
So they really have no idea and are admitting that. But, since we've basically gotten no snow so far, this will probably be the same. I realize this season has been frustrating for forecasters. It is also frustrating for us - when threat of snow is what the news stations use for ratings, so they constantly pump up the expectations... While you have been cooling that down on your blog recently, it has been the case for you to stoke the fires as well- mostly by using the blokes from accuweather, who are just as bad as the local news, not to mention "Eric the Red" who also seems to favor the more dramatic forecasts.
Posted by: Dave | January 23, 2011 8:10 AM
Annie,
Any weather forecast (prediction) greater than 24 hours in advance is, at best, an educated guess. Weather and climate contain so many unpredictable variables that it is impossible to give a precise forecast days in advance. It's not that these people can't read the radar. It's Sunday morning and we can safely say that some precipitation event will be here by Wednesday. Monday night/Tuesday morning we'll have a great idea of exactly what type and how much precipitation. No kids will get stuck at schools. They close at the first mention of snow...and people will overreact and go buy all the bread, toilet paper, and milk in the stores as if they won't be able to leave there homes for a month.
Posted by: Shane | January 23, 2011 8:50 AM
Frank,
All winter long the northern stream has dominated in these phasing scenarios either delaying the storms development (Northeast from NJ on gets pounded) or pushing it off the coast (what were those clowns talking about). The models are backing in that direction over night. They will flip-flop right up until you're just as well off looking at radar, local wind direction and cloud types. Old school:)
My GUESS is another grazing coastal slider on Wednesday gives us a dusting or flurries.
Posted by: Cumulus Maximus | January 23, 2011 10:38 AM
It used to be that NC/southern VA had most of this kind of weather--especially big ice storms as opposed to rain- or snow-only. We up here used to get mostly snow. Now it seems like wherever that "line" was between ice and snow is moving north toward us. Maybe this is a factor in this series of "iffy" storms we've been having.
Posted by: Larry Esser | January 23, 2011 10:39 AM
Weather.com has the Wednesday map with Maryland right in the middle of the snow. And according to their site, it could be a biggie.
Posted by: G | January 23, 2011 11:03 AM
Annie,
"Reading the radar" only works DURING the event when precipitation is occuring. This is called 'nowcasting' and yes, forecasters use the radar when precipitation is actually falling. There is nothing on the radar right now from this system. This storm doesn't even exist yet. It is an upper-level disturbance over British Columbia (Canada) that will propagate south and form a surface low along the Gulf Coast. The rain "on the radar" in Texas and Arkansas has nothing to do with the anticipated storm system for Tuesday/Wednesday.
The atmosphere is a fluid described by complex mathematical equations. There are a variety of computer models that use different parameterizations and resolutions, resulting in varying solutions. Sometimes the models "agree" on a solution, and sometimes they "disagree." Some models handle certain phenomenon better than others (e.g., tropical models handle tropical cyclone intensification and motion better than other global models).
To suggest that forecasters go out and make note of the cloud type (even if the sky is clear), read the radar (even when there is no precipitation showing up on it), and use their knee pain an an indication of approaching rain is simply ludicrous. It's unfortunate that so many people fail to see the complexity of the very atmosphere that they live within.
So, I challenge you to look at the radar, look out your window, measure the wind, then formulate a forecast (without cheating by reading someone else's forecast) to tell me when/where the surface low will form, how it will deepen/propagate, where the rain/snow line will be in 72 hours, and exactly how much snow you will see at your house, if any. If not snow, then will it be rain? If so, how much? Could you see high wind? What about flash flooding? Again, look only at your radar. :)
Posted by: chris | January 23, 2011 5:47 PM