127
FXUS10 KWNH 301721
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1220 PM EST THU JAN 30 2020
VALID JAN 30/1200 UTC THRU FEB 03/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PRELIMINARY PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...EVOLUTION OF TROUGH OVER EASTERN HALF OF THE U.S. INTO SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~
PREFERENCE: 12Z GFS/NAM AND 00Z ECMWF/UKMET
CONFIDENCE: AVERAGE
A FULL-LATITUDE TROUGH DOWN THE CENTER OF THE CONUS INTO NORTHERN
MEXICO IS BEING DUG BY A PRIMARY LOW CURRENTLY OVER NORTHWEST
MEXICO WITH A SECONDARY, REINFORCING TROUGH PUSHING DOWN THE
NORTHERN HIGH PLAINS. THE SECONDARY TROUGH SHIFTS SOUTH INTO
NORTHERN MEXICO THROUGH FRIDAY, KEEPING THE SOUTHERN END OF THE
TROUGH POSITIVELY TILTED ACROSS THE GULF COAST THROUGH SATURDAY
BEFORE SHIFTING EAST OF FL SATURDAY NIGHT. EMBEDDED IMPULSES IN
THIS TROUGH VARY AMONG GUIDANCE, BUT THERE IS NOW DECENT AGREEMENT
ON POSITION AND MOVEMENT OF THESE FEATURES OUTSIDE OF THE 00Z CMC.
THE NORTHERN PORTION OF THE TROUGH AXIS IS EXPECTED TO PUSH THOUGH
THE MIDWEST SATURDAY AS THE SOUTHERN TROUGH AXIS MOVES ACROSS THE
SOUTHEAST.
AT THE SURFACE, LOW DEVELOPMENT OCCURS FRIDAY NIGHT ALONG THE NC
COAST IN THE LEFT EXIT OF A STRONG SOUTHWESTERLY JET STREAM.
INTERACTION OF THESE TWO FEATURES IN THE UPPER LEVELS IS DELAYED
UNTIL SATURDAY NIGHT ALONG THE SOUTHERN MID-ATLANTIC COAST WITH
THE SURFACE LOW WELL OFF NEW ENGLAND AT THAT TIME WHEN IT RAPIDLY
DEVELOPS. THERE IS EXCELLENT AGREEMENT IN DAY 2 QPF OVER THE
CAROLINAS, MID-ATLANTIC COAST AND FAR SOUTHEAST NEW ENGLAND AMONG
THE 12Z NAM (MORE SO THE 3KM NAM)/GFS AND 00Z UKMET/ECMWF.
THE TILT OF THE SOUTHERN PORTION IS MORE POSITIVE THAN PREVIOUS
RUNS WHICH SLOWS THE COLD FRONTAL PROGRESSION OVER THE FL
PENINSULA FRIDAY NIGHT AND RESULTS IN A WEST TO EAST QPF SWATH
OVER THE FL PENINSULA ON DAY 2. THE ONLY DIFFERENCES IN THE 12Z
NAM/GFS AND 00Z ECMWF/UKMET ARE LATITUDINAL POSITIONING OF THIS
SWATH SOMEWHERE AROUND LAKE OKEECHOBEE.
THE 00Z CMC IS AN OUTLIER IN THAT IT BRINGS THE NORTHERN AND
SOUTHERN PORTIONS TOGETHER SOONER AND FARTHER SOUTH (LATE SATURDAY
OVER THE SOUTHEAST) AND WEAKER THAN THE CONSENSUS, SO IT IS NOT
PREFERRED.
...PACIFIC NORTHWEST ATMOSPHERIC RIVER LEADING A LONGWAVE TROUGH
PUSHING INTO THE WEST ON SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/NAM AND 00Z UKMET/ECMWF
CONFIDENCE: AVERAGE
AN ATMOSPHERIC RIVER REACHES THE WA COAST LATER TODAY AND WAIVERS
NORTH/SOUTH THROUGH FRIDAY NIGHT BEFORE SHIFTING SOUTH DOWN THE OR
COAST SATURDAY IN ADVANCE OF A LONGWAVE TROUGH THAT REACHES TO
CENTRAL CA AS IT PUSHES INLAND SUNDAY. THE DILEMMA COME WITH THE
EXACT QPF AXIS ON DAY 2 AND THE TIMING OF THE TROUGH THAT MOVES
ASHORE ON DAY 3. THE 00Z ECMWF REMAINS A STEADY 6 TO 12 HOURS
BEHIND THE REST OF THE GUIDANCE WITH THE TROUGH AXIS, SO IT HAS
QPF LESS INLAND ON DAY 3. THE 12Z GFS REMAINS FARTHER NORTH WITH
THE FORCING ON THE NORTH SIDE OF THE MOISTURE PLUME WITH THE DAY 2
QPF FOCUS ON SOUTHERN VANCOUVER ISLAND. BOTH OPERATIONAL MODELS
ARE IN LINE WITH THEIR ENSEMBLE MEANS.
THE DAY 2 QPF AXIS HAS NORTHERN SOLUTIONS WITH THE 12Z NAM/GFS AND
SOUTHERN IN THE 00Z ECMWF/UKMET WHICH ARE FOCUSED ON THE NORTHERN
OLYMPIC PENINSULA WITH THE 00Z CMC IN BETWEEN. DAY 3 QPF IS IN
GOOD AGREEMENT AMONG THE 12Z NAM/GFS AND 00Z UKMET. THE 00Z CMC IS
THE FASTEST SOLUTION THE SLOWEST SOLUTION WITH THE TROUGH AXIS ON
DAY 3 AND IS NOT PREFERRED. THE 00Z ECMWF SHOULD HAVE THE LEAST
WEIGHT ON DAY 3 GIVEN ITS SLOW PROGRESSION.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
JACKSON
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page