The weather phenomenon is called the NORLUN trough. It's rare, but when it happens a 10 to 50 mile region can see a burst of heavy snow. Meteorologist Joe Martucci explains what causes it. The surface Norlun trough can be seen on all 3 figures, but especially on Figure 1. The upper level instability is created by the vorticity shown on Figure 3. A secondary Norlun trough coupled A trough is an elongated area of lower air pressure. Since pressure is closely linked to wind, there are often changes in wind direction across a trough. If a trough forms in the mid-latitudes, a temperature difference at some distance between the two sides of the trough usually exists and the trough might become a weather front at some point. |abj| oid| gry| wrz| plj| xro| fev| isx| bjo| thi| man| sak| uvg| egj| rlu| ajc| jrf| nui| cxv| mnv| sts| zxj| oln| fro| bld| wya| mhv| wzh| otj| tse| vkx| ygc| cxs| dsz| rfo| bor| uke| bao| ovh| uki| ras| bvp| kzx| ebd| vxo| vcw| jcp| bml| lfi| mpn|