Re: H85
Posted by AlligatorPointer on 1/5/2014, 3:01 pm
Clarification regarding the H85 temp. ... These H85 discussions are from posts by meteorologists found online by searching for "H85 weather"... such as this one: "H85 is in reference to the 850 mb level. The 850 mb chart (like the 700mb[H7], the 500 mb chart [H5]. etc is a chart that gives the wind, temperature, and dewpoint as well as the height of the surface where the air pressure is 850 mb. All temperature values on the upper air charts are in Degrees C and all heights are in geopotential meters. The 850 mb chart is used for many purposes including noting the advection of moisture, warm and cold air and noting whether or not the precipitation is likely to fall as snow, rain, or freezing rain."

"There are old rules of thumb about the thermal structure around an H85 low, such as snowfall is not possible until H85 temps are at or below -3 C to the nw of the low center, etc. This is a poor man's way of determining if a warm nose around or above H85 may persist or perhaps if the sfc-based layer is cold enough to support snow. H85 flow is also a good proxy in determining the degree of llvl moisture flux into the storm system. The best llvl forcing in terms of frontogenesis shows up more clearly in geostrophic flow (regions off the ground mostly unaffected by friction)...generally in the H85-H7 layer. The configuration and modification of frontogenetical areas through time can give a good indication of where the heavier snowfall rates may occur.
If the 850 low goes to your west, you're in the warm sector and getting rain most likely (unless there is a very cold antecedent air mass). If it goes east, then you have a shot at seeing snow."
185
In this thread:
BLIZZARD WARNING - Fred, 1/1/2014, 4:14 pm
< Return to the front page of the: message board | monthly archive this page is in
Post A Reply
This thread has been archived and can no longer receive replies.