Looks to be another difficult weather day here in the Tucson area. The downslope, easterly winds continue this morning and have been gusting 25-30 mph along the Rillito wash. The CIRA blended PW product for 6 am MST is shown above (light blue - dark green indicates PW values from 25 to a bit over 30 mm) and indicates a dry region over southwest New Mexico and southeast Arizona, generally west of the Continental Divide. Higher PW is currently pinched into a narrow zone from south-central Arizona north-northwestward to the Lake Mead region. The early run of Mike Leuthold's version of the WRF-GFS model forecasts the east winds to continue through most of the day - graphic below shows forecast of 10-m winds valid at 4 pm MST this afternoon. These winds are strongest from along the Continental divide westward across Cochise County. A confluent zone is again forecast across western Pima County. From late evening on the model forecasts increasing PW and conditions becoming more favorable for storms and rain.
The skew-T plot of TUS upper-air data for 12 UTC this morning is shown above and indicates warm temperatures and drier air below 700 mb. The SPC diagnostics indicate a small layer of CAPE that is limited by an ugly inversion centered at 500 mb. The forecast skew-T for TUS at 4 pm this afternoon is shown below - the inversion has vanished in the forecast, which is good if it actually does shift westward. Deep easterly flow is forecast and the atmosphere over Tucson is totally devoid of CAPE. In contrast, east of the Continental Divide, and also east of the long-watched inverted trough, winds are southerly to southeasterly and the troposphere is very moist.
The WRF-GFS forecast of total rainfall through midnight tonight is shown above - forecast rainfall is very sparse except east of the Continental Divide and south in Sonora. A check of the new morning forecasts from Atmo will be very helpful today. The new NAM forecast this morning appears similar to the early WRF-GFS, with most activity suppressed today but chances for storms and rain improving during the night.
No comments:
Post a Comment