Tuesday, December 25, 2012

fog below... (pm.25.dec.12)>

Christmas Day stats:

Early morning low temp: 46.6F (8.1C)
Afternoon high temp: 55.9F (13.3C)
Rainfall: none

We have clear skies in McLeod shortly after sunset this Christmas evening, but it looks like a classic temperature inversion is in progress just downhill from us, with haze and light fog below about the 1500m/4900ft level.  There has been widespread fog across the plains of north India again today, thanks to a shallow layer of colder air trapped below warmer air aloft.  We've had none of that up here, with lots of sunshine, along with temps running a bit above normal once again.

It's fairly normal for the winter fog plague to begin during the last 10 days or so of December, and this year is proving thus far to comply.  The pattern in the upper atmosphere remains very quiet, with a weak ridge of high pressure in control.  However, there have been periodic surges of slightly colder air spilling in from the northwest, which quickly funnel through the valleys and down into the plains, creating the fog scenario down there.

There should be no major changes during the next 36-48 hours or so, but starting late on Thursday, a large low pressure system will begin to ease its way into northwest India from the west.  Although this system will have a large counter-clockwise circulation center associated with it -- although there will be a good amount of dynamic energy -- and although there will be a pool of very cold air in the upper-atmosphere at its center -- it remains to be seen whether there will be any appreciable moisture drawn into it, to serve as fuel for significant rain and snowfall.  Computer models remain consistent in forecasting only light amounts of precipitation from late Thursday into Sunday, but things could change, so stay tuned for updates.

TUESDAY NIGHT:
some patchy fog possible, otherwise mostly clear.
low: 8C (46F)

WEDNESDAY:
sunny to partly cloudy.
high: 13C (56F)

WEDNESDAY NIGHT:
fair to partly cloudy.
low: 9C (48F)

THURSDAY:
clouds thickening up, but some sun as well.  chance of a couple of rain showers by late afternoon.
high: 14C (57F)

FRIDAY:
partly to mostly cloudy and a bit cooler.  a couple of rain showers possible.
morning low: 8C (46F)
daytime high: 12C (54F)

SATURDAY:
mostly cloudy and cooler.  good chance of a shower or two in the area.
morning low: 6C (43F)
daytime high: 11C (52F)

SUNDAY:
seasonably cool, with a mix of clouds and some peeks of sun.  good chance of a shower or thundershower.
morning low: 4C (40F)
daytime high: 10C (50F)