6 replies to this topic

[bugalou]

I was curious about this and wanted to hear it from the pros.  What is the hardest weather to predict in a typical short range (≤ 120 hrs) forecast.  I am sure opinions will vary from region to region.  Please tell us what gives you trouble and why.
As an amateur in the mid-south area, winter weather (especially ice) tends to frustrate me the most and seems almost impossible to predict until it is occurring.  Most of the models are useless for this too.

[NWIASpotter]

Well the easy answer is that all weather is hard to predict, hence the reason why the public will generalize in that meteorologists can't really predict the weather...  

In reality, I find that winter weather is by far harder to predict than convective weather during the summer months...  As you mentioned above, the hardest times seem to come when the event is going to be a mixture of precipitation types (rain/sleet/ice/snow) and trying to accurately forecast what type is going to fall and more importantly how much is going to fall over a specific area.  Events such as those always seem to include something that is very hard for forecast models to catch, such as evaporative cooling, etc...

So my vote goes to winter weather, specifically those border precip type events.

[bigme100]

Well the easy answer is that all weather is hard to predict, hence the reason why the public will generalize in that meteorologists can't really predict the weather...  

In reality, I find that winter weather is by far harder to predict than convective weather during the summer months...  As you mentioned above, the hardest times seem to come when the event is going to be a mixture of precipitation types (rain/sleet/ice/snow) and trying to accurately forecast what type is going to fall and more importantly how much is going to fall over a specific area.  Events such as those always seem to include something that is very hard for forecast models to catch, such as evaporative cooling, etc...

So my vote goes to winter weather, specifically those border precip type events.

Agreed that winter typically is the toughest.  One of the things I've found frustrating are multiple-wave events, both in winter and in summer.  Get an initial weaker shortwave touching off convection/precipitation then a big digging trough in behind it that spins up a big cyclone 12 hours later or however.  It's especially tough with convection where you might have a big event if not for cloud cover/overturning caused by the leading wave.  In the winter it can goof up your available moisture and temperature fields, and if it doesnt change that, it makes the timing tough to nail down in the mid-range, and sometimes short-range.

[kg4gke]

I was curious about this and wanted to hear it from the pros.  What is the hardest weather to predict in a typical short range (≤ 120 hrs) forecast.  I am sure opinions will vary from region to region.  Please tell us what gives you trouble and why.
As an amateur in the mid-south area, winter weather (especially ice) tends to frustrate me the most and seems almost impossible to predict until it is occurring.  Most of the models are useless for this too.

Also agreed about winter weather. So many minor changes can take place from hour to hour and from region to region, especially within a broadcast coverage area.

Topography plays a great part in how much or what kind of precip will be expected and/or received. When I worked at the Fort Smith offices of KFSM-TV 5 about 10 years ago, the Boston Mountains between Fort Smith / I-40 and Fayetteville were notorious for receiving freezing mist/freezing drizzle anywhere from late autumn to early spring when the conditions were correct. The models never took into account the height differences or the temperature difference between the higher mountain passes and the lower Arkansas River valley, which accounted for some missed (not just on my part) forecasts of freezing precip.

The minor minor perturbations of the atmosphere - the kind that will never be demonstrated on any modern model - whether temperature, moisture or energy - are the problems that help to really send a forecast off the deep end from snow to rain or vice versa. One of my senior class projects @ KU was an in-depth post mortem of a winter weather forecast and the models used to predict them, and the changes in the forecasts made from the previous decades. Very eye opening in its own way about both how far model prediction has come, and how much public perception about forecasting still remains close to the "aw, it's all guesswork anyway" attitude.

[stormvideoman]

Without question for me it is also winter weather for all the great reasons already mentioned.

[Delta Golf Sierra]

I agree with the above posters - winter weather, and especially precipitation type, is the most challenging forecast. It is difficult because it only takes very slight temperature changes at various levels in the atmosphere to change rain into freezing rain into sleet into snow.

I'd say that fog forecasting can also be very difficult. Often conditions look ideal for fog, but you get nothing. It is so highly dependent on the local topography and extremely sensitive to the slightest changes in wind, cloud cover, humidity, and temperature. Model guidance is often no help at all with fog because it can't resolve such fine details.

[bigme100]

I'd say that fog forecasting can also be very difficult. Often conditions look ideal for fog, but you get nothing. It is so highly dependent on the local topography and extremely sensitive to the slightest changes in wind, cloud cover, humidity, and temperature. Model guidance is often no help at all with fog because it can't resolve such fine details.

Agreed!  It can be pretty hard to differentiate between the marginal 1-3 SM visibliity fog events and the more widespread M1/4SM events too, both with advection and radiation fog.  You really have to be on point and pick all the details out, and even then sometimes its hard to hit it.