Tuesday, January 09, 2018

Quick Update AM 9 January

At 13 UTC (6:00 am MST) the upper-tropospheric, closed low is still over the ocean, west of Santa Barbara - above is water vapor image for that time. The cyclone is about where the 00 UTC operational GFS forecast it to be. The  MIMIC TPW analysis from CIMMS at Univ. of Wisconsin (below for same time) indicates a weak atmospheric river south of the cyclone. The broader band of higher PW from the tropics is being pushed southward by the digging cyclone, so that feature is apparently not a player for here late afternoon and tonight. Forecasts from the 06 UTC WRF-GFS at Atmo keep the PW at TUS below an inch through this entire event - so it is coming across Arizona as the atmospheric river weakens rapidly.

The regional radar (base scan - which suffers from terrain blockage in the West) is shown second below at 1335 UTC - from NCAR. Some precipitation has just made it into northwest Arizona at this time. The 06 UTC GEFS QPF plumes for TUS continue clustered around 0.20 inches.

The model does forecast strong southwest to west winds for southeast Arizona during the middle of the night, ahead of and with the cold front - forecast of 10-m winds above is valid at midnight tonight.

The forecast skew-T for TUS (below valid at 10:00 pm) does generate some CAPE, and there is a chance of embedded thunderstorms tonight (as per Mike Leuthold's comment yesterday), especially to our north.

It's now a wait and watch game.

1 comment:

  1. BUFR soundings all show increasing deep-layer shear this afternoon along with moderate low-level helicity...thus there appears to be a chance for some low-topped supercells across the western part of the state during the afternoon and evening.