UA WRF Forecast Discussions

  Overview: Complicated forecast today due to a series of small-scale vortices forecast to propagate west-northwestward between an upper-level low situated over the Gulf of California and a broad high pressure system centered in northeastern Texas. The feature most pertinent to today's forecast is a mesoscale vortex (MCV) located near the border of Chihauhau and Sonora Mexico with the northern extent reaching into extreme southwestern New Mexico. This feature is forecast to approach the greater Tucson area between 3 and 6 PM. Convection is already developing ahead of this feature more aggressively than forecast over Cochise and Santa Cruz counties. Cirrus blowoff is spreading rapidly NW and may act to minimize destabilization over the Tucson metro. Anvil shading not withstanding, the MCV could provide enough ascent and shear in given sufficient destabization for convection to organize in the as we approach late afternoon. Given the potential for organization, the Storms Prediction ...

Synopsis A subtle shortwave embedded within the northeast quadrant of an upper level low over the Central Gulf of California produced overnight /early morning showers and thunderstorms across Southeast Arizona. This feature has moved northwest this morning leaving subsidence in its wake across the region. Convection will be suppressed across the area with only an isolated cell or two possible over the higher terrain and near the International Border this afternoon. As the upper level low moves northward throughout the day today and into tomorrow, models forecast another, more potent shortwave embedded in the northeast quadrant of the low to move through Southern Arizona. CAMs forecast an increase in storm activity tomorrow, but the coverage and intensity of convection will be primarily dependent on the timing of the passage of the shortwave. Current Conditions The 12z GFS 500mb analysis this morning displays the subtropical anticyclone over the Southern Plains, an upper level ...

  Overview: Upper-level troughing over the the Western US has pushed the upper-level anticyclone off to our east, turning the 500 hPa flow to southerly across southeastern Arizona. Further west, southwesterly flow associated with the upper-level trough has allowed dry air to push into western Arizona with a significant dewpoints gradient across western Maricopa and Pima counties. This surface dewpoint gradient should encroach on the Phoenix metro area during the course of the day and may be a focus for some very short lived convection developing off of the North Maricopa mountain range. Closer to Tucson, deep moisture is well established with precipitable water values this morning close to 1.7". Cloud cover this morning has been slow to burn off west and south of Tucson, although convective inhibition is dissipating fairly quickly as indicated by a developing cumulus over Cochise county as of 10:30 AM this morning. Fairly uniform but relatively weak southerly flow above the bounda...

  Synopsis The 500mb anticyclone will be centered over South-Central/Southeastern Arizona today. This synoptic pattern is characteristic of decreased storm activity with coverage remaining confined to mainly the higher terrain of Southeast Arizona. The anticyclone is expected to shift east tomorrow and become anchored in Southern New Mexico with weak southerly/southeasterly flow aloft in Southeast Arizona. In addition, a subtle shortwave is forecast to move northward into Southeast Arizona which could allow an uptick in storm coverage tomorrow afternoon. The majority of activity will remain to the south and east of Tucson, but a few showers and storms are possible in the vicinity this weekend with better chances tomorrow.  Current Conditions   A trough moving into California continues to flatten the mid level subtropical ridge and is displacing the anticyclone to the south and east. 12z 500mb analysis this morning shows th...