Yesterday’s Weather
As advertised, the warm air aloft has kept surface temperatures hot and limited convection to a few isolated storms in northeast New Mexico. The backdoor cold front went through Tucumcari around 18Z. Smoke from the fire southeast of Silver City has spread east in a v-shape and is as far east as Roswell and Carlsbad. The smoke is mostly elevated but as the winds have dropped overnight, surface visibilities are now higher. Another fire in southern Utah is spreading some smoke into northeast Arizona. The visible satellite imagery from yesterday shows the smoke area from both fires.
The smoke plume from the Silver City fire has been mixed out and if more smoke is generated by that fire, the upper flow will force it more to the south rather than east. Aerosol optical depth forecasts show the smoke event active again today and tomorrow.
Analysis
Upper-level flow at 250 mb has turned northwesterly across the region with wind speeds decreasing. In the Pacific northwest, a strong storm system is approaching the Oregon/Washington area, and this will affect us over the weekend with a 10 degree F drop in high temperatures.
At 500 mb, the high pressure has shifted a little to the west with a large area of warm –5 C air from northwest Mexico into southern California.
The ridge at 700 MB is vertically stacked with the 500 mb ridge. Dewpoint temperatures are around –15 to –20C.
Today
The 12Z (5am) upper air sounding from Phoenix doen’t show much wind flow below 500 mb and obviously no CAPE and the mixed layer height is close to 500 mb.
Arizona and New Mexico will be precipitation free as the dry air aloft suppresses any development. In New Mexico, the cold front has already moved south into west Texas. Surface dew points are in the 60s over there, but as the 5am Midland, TX sounding shows the cap will be too strong today (see strong inversion or “cap” where temperature, shown by the red line, increases with height just above the surface).
Tomorrow
As the low pressure trough in the Pacific northwest moves by to the north of the area the ridge will be depressed south. Monsoon flow will set up across New Mexico with mainly mountain storms developing with very little rain reaching the ground. The potential to start more fires will be high in New Mexico!
Arizona will remain dry and this should be the hottest day of the year. Temperatures upto 114 F in Phoenix, 115 F in Gila Bend, and 111 F in Tucson.
Outlook
The monsoon circulation shifts westward so that central New Mexico and far southeast Arizona has storms by Friday and Saturday. Once again not much precipitation will be reaching the ground for these events either and the main threat will be dry lightning. As the low pressure trough passes by to the north, the monsoon flow shifts its orientation from south to north flow to southwest to northeast flow. More to discuss on this tomorrow and Friday.
Discussion written by Pat Holbrook