As previously mentioned, an active weather week is indeed taking shape, some of the forecast details have changed (as is common) but the overall pattern still looks to be on track.
First up is the nor’easter set to impact areas hard hit by recent Superstorm Sandy. Overall this forecast remains the same. Surface low pressure, now beginning to take shape over the south, will rapidly deepen and ride up the eastern seaboard. Luckily this system won’t make “landfall” as Sandy did, which is common in these more classic nor’easter type setups. Despite a storm that won’t be as intense, the storm is still a formidable ones. Surface winds should easily increase to 30mph with higher gusts (some approaching 50mph or more) along the coast. The high winds and surf will certainly hinder ongoing recovery efforts. Snowfall is still a possibility, but this looks like it will best hit locations further from the coast. Snowfall amounts do not look to be too significant, but the snow that does fall will be the heavy wet type and could stress powerlines and other structures weakened by the recent storm.
Below is a GFS plot for Wednesday night showing a tightly wrapped surface low just off the coast with winds in excess of 50kts in some spots.
Various watches and advisories have already been posted along the coast, and residents need to take note.
Latest advisories can be found here: http://www.nws.noaa.gov/largemap.php
As this system departs, attention then turns to the potential severe weather maker that could affect the plains, midwest and ohio valley. There have been some changes in recent runs, but these were changes that models were trending towards. It appears a blocking pattern will stall the progression of the trough and prevent it from sweeping across the nation in a couple days. Instead, the trough will lag a bit, with multiple waves of energy riding along it, spinning up multiple storms instead of just one.
The timing is overall the same, and the southern plains could see their chance at severe weather Saturday. All modes would be possible but would still favor a quickly moving squall line. This storm makes a dip south before rocketing towards the Hudson Bay, aided by a very strong fall jet stream. The plot below is for Friday and shows the storms initial formation.
Right in the wake of this system, another low may quickly form, prolonging the period of unsettled weather for parts of the midwest. This is one of the bigger changes to the forecast, but again it was one that models were trending towards. Much like the first system, rain and storms will be the norm along the cold front with potential wintery weather on the back-side. Instability appears to be largely lacking, but with strong shear and forcing in place, it may be enough to force up some low topped storms capable of wind damage in the form of a narrow squall line that sweeps across the midwest though the ohio valley.
Of note is this system could bring the first light dusting of snow for parts of the corn belt. One ecstatic run of the EURO even has an all-out snowstorm for parts of Kansas up through Iowa/Illinois/Wisconsin for next week, but that would appear to be an extreme case. Still an interesting forecast development that will need to be monitored. More details will be posted as the forecast becomes clearer.
The storm parade doesn’t stop here though, with models showing more storms developing in the longer rage. It is a bit silly to try and make a specific forecast once we get into this time frame, rather it is only worth noting the pattern appears to be an active one, and folks should be ready for repeated rounds of unsettled weather.