237
FXUS10 KWNH 230858
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
357 AM EST SAT NOV 23 2019
VALID NOV 23/0000 UTC THRU NOV 26/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...CYCLING CLOSED LOW EMERGING OHIO VALLEY, POTENTIALLY PHASES
WITH NORTHERN STREAM SHORTWAVE ACROSS GREAT LAKES SAT INTO SUN
SUPPORTING ASSOCIATED SURFACE LOW MOVING FROM THE LOWER OUT OF
TENNESSEE VALLEY INTO THE CENTRAL APPALACHIANS FRIDAY NIGHT INTO
SATURDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS/UKMET/ECMWF BLEND
CONFIDENCE: AVERAGE
09Z UPDATE: NO SIGNIFICANT CHANGES WITH THE 00Z UKMET AND ECMWF
NOW AVAILABLE. THE PREVIOUS PREFERENCE FOR A GFS/UKMET/ECMWF BLEND
LOOKS SUFFICIENT.
CLOSED UPPER LEVEL LOW CURRENTLY SEEN IN GOES WV IMAGERY OVER THE
CENTRAL PLAINS WILL MOVE EASTWARD TOWARD THE OH VALLEY IN THE NEXT
12-24 HOURS. MEANWHILE, SHORTWAVE ENERGY IS QUICKLY DROPPING
THROUGH THE NORTHERN PLAINS. THESE PIECES OF ENERGY ARE FORECAST
TO PHASE INTO DAY 2 AND PRODUCE A NEGATIVELY TILTED TROUGH OVER
THE NORTHEAST U.S. WITH AN ASSOCIATED AREA OF LOW PRESSURE OFF THE
MID-ATLANTIC COAST. A LOOK AT THE MOST RECENT GUIDANCE SHOWS THE
00Z NAM A BIT TOO AGGRESSIVE WITH THE 500 MB TROUGH AND AT THE
SURFACE, THE LOW TOO FAR WEST / CLOSE TO THE COAST. MEANWHILE, THE
12Z CMC LOOKS A BIT OUT OF PLACE AND IS TOO FAST TO LIFT THE
SHORTWAVE THROUGH NEW ENGLAND ON DAY 2. THE GFS, ECMWF, AND UKMET
ALL APPEAR FAIRLY REASONABLE SOLUTIONS AND HAVE SHOWN FAIRLY GOOD
RUN TO RUN CONSISTENCY WITHIN THE ENSEMBLE SPREAD, SO FOR THIS
CYCLE THE PREFERRED BLEND WILL BE THE 00Z GFS, 12Z UKMET, AND 12Z
ECMWF.
...EMBEDDED SHORTWAVES WITHIN STRONG ZONAL NORTHERN PACIFIC JET
INTO THE NORTHWEST...
..ASSOCIATED SURFACE WAVE ACROSS THE NORTHERN TIER BY 00Z MON
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 25.00Z; GEFS/ECENS BLEND
THEREAFTER
CONFIDENCE: AVERAGE
FAIRLY ACTIVE NORTHERN STREAM ENERGY WILL BRING A PARADE OF
SHORTWAVES ACROSS THE NORTHERN TIER OF THE U.S. DURING THE SHORT
TERM PERIOD WHILE A LARGE CLOSED LOW DRIFTS WELL OFFSHORE THE
SOUTHERN CALIFORNIA COAST. THE LARGE SCALE SYNOPTIC SETUP AND
EVOLUTION IS FAIRLY REPRESENTED BY THE VARIOUS DETERMINISTIC
MODELS THROUGH ABOUT 48 HOURS, HOWEVER, AS THE WAVES CREST THE
CANADIAN ROCKIES THERE IS FAIRLY SIZABLE SPREAD. THE 00Z GFS IS
TOO AMPLIFIED AS THE TROUGH DIGS ACROSS THE ROCKIES ON DAY 3, WELL
OUTSIDE THE ENSEMBLE SPREAD AND ALSO IS A BIT FAST COMPARED TO THE
REST OF THE DETERMINISTIC TIMING ON DAY 3. OTHERWISE, THERE IS
SOME TIMING DIFFERENCES WITH THE UKMET, PARTICULARLY WITH THE
UPSTREAM SHORTWAVE COMING INTO THE PAC NW TOWARD THE END OF DAY 3.
GIVEN THE LARGER THAN USUAL SPREAD IN THE MODELS, THE DAY 3
PREFERENCE IS FOR MORE USE OF THE GEFS/ECENS MEANS, WITH A GENERAL
MODEL BLEND FOR THE FIRST 48 HOURS OF THE FORECAST.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
TAYLOR
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