WEDNESDAY: 11-NOV-15 / 3:00 PM CDT
NEXT FULL WX UPDATE FRIDAYPOSTING SCHEDULE: ‘FULL’ UPDATES ON MONDAYS / FRIDAYS … TEMP FORECAST CHARTS ON WEDNESDAYS AND WHEN WARRANTED
MILD WEATHER WITH 3 MAJOR STORM EVENTS
Little change to the overall pattern of a mean upper level TROF over the western half North America and ridging to the east for the next 10-12 days. A powerful storm in the Mississippi Valley with high winds & locally severe T-Storms will move into Great Lakes with the southern trailing cold front sweeping off the east coast by Friday AM. At the same time, a new storm moving into the PAC NW will bring very heavy Precip to the coastal PAC NW and snow to the Cascades. The associated upper level TROF will move quickly across the Rockies on into the lower Plains with a strong storm formation and somewhat stronger cold front triggering another round of heavy Precip (including isolated T-Storms) by Tuesday which will pass off the east coast later next week. This stormy pattern will likely repeat 6 days later going into the Holiday weekend.
Caveats: The global models are once again flip-flopping between model runs in their longer range solutions, with forecast anomaly swings of over 30 degrees(!) for the Week 2 period between model cycles. However, the GFS ensembles have trended towards a more zonal-like flow across the nation by he last week of NOV - and while this typically results in above normal Temps in the winter over the eastern US - the very strong storm systems will likely manage to get Temps down to near or below normal levels going into Thanksgiving before moderating again by the start of DEC.
Fig 1: Temperature ANOMALY forecast for Week 1 is based STRICTLY on the MOS data forecasts from the todays 12Z operational GFS model run with only minor adjustments towards the raw model data points for Days 6 and 8. Well above normal Temps are expected east of the Rockies and below normal in the west during Week 1 – with colder Temps in the Midwest and east during the weekend before warming up early next week ahead of the next storm system. Overall Confidence in the forecast anomaly Pattern and Magnitude is above average for this time of year, with a reading of ‘4’ for the pattern and a ‘5’ for the anomaly magnitudes - on a Scale from 1 to 5.
Fig 2: The Week 2 Temperature ANOMALY forecast is based on the 12Z run of the GFS (70%) integrated with the 12Z GFS Ensemble (30%) (ECMWF N/A) using the projected pattern along with explicit surface and 850mb (~5,000 FT) Temp forecasts. Some Temps are adjusted for known or expected anomalous thermal patterns & projected storm system passages.The latest GFS forecast calls for a stronger cold air surge into the US behind next week’s strong storm – and with lowering heights shown across the entire nation by the end of Week 2, Temps will average below normal across much of the central and southeastern US. In deference to warmer solutions in earlier model runs, and the milder GFS Ensembles, I’ve added 1 to 3 degrees to the GFS forecast anomaly values. Confidence is solidly below average for this time of year due to the large run-to-run differences, with readings of ‘2’ for both the pattern and magnitude on a scale of 1 to 5.
Fig 3: GFS 15-Day Precipitation Pattern Loop (for mounts greater than 0.10” only) A major storm in the central US with locally severe T-storms will weaken as it passes off the east coast by FRI AM, with another major storm formation in the central US around TUE – and a third storm forecast at the start of Thanksgiving weekend.
Fig 4: Temperature Anomaly Forecast for Alaska during Week 1 The first truly cold arctic air outbreak since last winter is developing over Alaska, but the latest GFS model shows a rapid and strong warm-up statewide during Week 2.
Posting Schedule: ‘FULL’ UPDATES ON MONDAYS & FRIDAYS … TEMP FORECAST CHARTS ON WEDNESDAYS AND WHEN WARRANTED
✭ The Next FULL WEATHER Update will be on FRIDAY✭
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Steve
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