Browse Month

February 2012

Winter Storm Threat: Feb 4-5 (final call)

Much better agreement on the models today. The main issues are still how warm the boundary layer is and how light the precipitation rates will be. I think plenty of areas SEE snow, but accumulations could be hard to come by outside of the higher elevations, so I cut back on my totals a bit:

 
I also adjusted the start/end times to account for the snow currently falling in OH/PA.

Summer 2012 (JJA) temperature forecast – First look

There may be wintry weather in the forecast, but it’s about that time of the year to take a look at what summer may bring us.

Here’s the summer composite:

Temperatures are close to -1F along the West Coast.

The monthly breakdown:

Forecasts are based on the 1981-2010 normals.

METHODOLOGY:

I grabbed some rough ENSO analogs this year that featured a La Niña winter with warm temperature anomalies in the U.S. and southern Canada. These analogs show a weakening Niña going into the summer months, which is the general consensus between the long-range models. I made adjustments to the temperature forecast based on current the soil moisture and forecast precipitation (summer precip. map getting released tomorrow), and that’s pretty much it. Keeping it simple this summer.

ANALOGS:
in [year (weight)] format

2000 (more)
1999 (more)
2008 (less)

RISKS:

The south-central and eastern U.S. could be warmer given the ongoing drought conditions from the southern Plains across the Southeast. The western Southwest could be cooler if the -PDO/-PNA combo. becomes a bigger player.

Winter Storm Threat: Feb 5-6 (first call)

THIS IS A LOW CONFIDENCE FORECAST. Keep that in mind.

 
There is a large amount of uncertainty given the different model runs both against each other and against themselves run-to-run. Surface temperatures will be a problem with this system, only compounding the forecast headaches heading into tomorrow night. I favored some phasing of the disturbance, but did not dig the system as far south and develop as much back-end precipitation as the 12z NAM. This forecast is a blend of the 12z NAM and 12z GFS.

The system will start as rain tomorrow afternoon/evening and will eventually change over to snow on the back end.