LATEST GUIDANCE HAS TRENDED A LITTLE DRIER ON PRECIP AMOUNTS AND HAVE LOWERED QPF AMOUNTS TO REFLECT THIS.
CURRENTLY A BAND OF PRECIPITABLE SEEN IN AMSU SATELLITE SOUNDER IMAGERY STRETCHES INTO THE ERN PAC TO NEAR THE OREGON OF UP TO 1.25 INCHES. BUT THIS BAND IS MOVING SOUTH AND WILL NOT LIKELY INTERACT WITH THE THE UPPER TROUGH AND COLD FRONT. IN FACT MODEL PWATS FOR LATE TONIGHT AND
EARLY FRIDAY ARE ONLY ABOUT 0.45 INCHES OR LESS OVER THE REGION.
MOST RECENT STORM SYSTEM WAS OVER FORECAST IN TERMS OF PRECIP AMOUNTS SO THINK THIS ONE MIGHT BE AS WELL.
That's from the Reno NWS 4:21AM PST Thu Nov 17, 2011 Area Forecast Discussion (Italics C/P)...right from "the horse's mouth"
I'm upgrading "MOST RECENT STORM SYSTEM WAS OVER FORECAST IN TERMS OF PRECIP AMOUNTS SO THINK THIS ONE MIGHT BE AS WELL." from chatty 4:21AM remark to the "Season Trend" so far.
So, I made a point of watching the local 10 O'clock News...sure enough Bill Martin, KTVU2's WeatherDude talked about the system (which did produce sprinkles here at the Ancestral Digs around sunset) He ran the models on the screen, and said: "I don't believe it! The models say this system will approach our coast, then just dry up and move southward along the coast. Tune in tomorrow night and I'll have the whole story for you"
Curious, I clicked on the NWS Monterey/San Francisco AFD to see if any forecast trepidation was in evidence. There it was!
"FROM PREVIOUS DISCUSSION...THE NAM AND GFS MODELS TRENDED MUCH DRIER THE LAST 24 HOURS AND KEPT THE MAIN LOW AND ASSOCIATED RAINFALL OFFSHORE. THE ECMWF HAS DEVIATED LITTLE AND BRINGS THE CORE OF THE LOW AND RAINFALL OVER THE DISTRICT...FOCUSED MOST HEAVILY FROM SANTA CRUZ MOUNTAINS SOUTHWARD THROUGH COASTAL MONTEREY COUNTY OVERNIGHT SATURDAY INTO SUNDAY MORNING. THE CANADIAN MODEL (GEM) IS CLOSER TO THE ECMWF THAN THE GFS AND FORECAST WILL TREND WITH THE WETTER MODEL SOLUTIONS AND THE CNRFC QPF. THIS EVENT IS VERY SIMILAR TO THE VETERANS DAY RAIN AROUND HERE WHEN THE NAM/GFS MODELS DEPICTED A DRY SCENARIO WHILE THE ECMWF BROUGHT THE MAIN FRONTAL BOUNDARY ONSHORE. WILL HOLD ONTO THE WET FORECAST THAT WE`VE HAD OUT BUT WILL BE INTERESTING TO
WATCH THE VERIFICATION OF THE EVENT."
This really got me thinking...so far this season the storms model wet, then slow down, dry out, and "under-perform"...the steering seems at odds with the model runs when all is said and done as well. This is the second storm in the last month that caused the forecasters to make note of model "disagreements".
I'd love to talk to one of these Lead Forecasters! I'd like to know how their models are refined over the years. Now that we're well into the Negative Phase of the PDO, does this become a background assumption factored into the works of the model itself? Maybe it's just another set of data points that weigh on the model's prediction.
Who writes the models? Do frontline forecasters give feedback to the model gurus? How do the models evolve with the long period variability of our climate? What happens when meteorology discovers new climate mechanisms or confirms previously discounted contributing factors?
Models don't agree? The more I ponder this, the more questions I have. Throw in the alphabet soup of oceanic oscillations and I get a headache!