236
FXUS10 KWNH 221655
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1255 PM EDT TUE OCT 22 2019
VALID OCT 22/1200 UTC THRU OCT 26/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z PRELIM MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CENTRAL U.S. CYCLONE; SECONDARY LOW FROM CAROLINAS TO NEW ENGLAND
TODAY-WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
A SURFACE LOW WILL CONTINUE TO LIFT INTO ONTARIO THROUGH THE NEXT
COUPLE OF DAYS WITH AN ASSOCIATED COLD FRONT TRAVERSING THE EAST
COAST. THE TROUGH AXIS WILL PIVOT THROUGH NEW ENGLAND WEDNESDAY
INTO EARLY THURSDAY. AS MUCH OF THE CONUS WILL BE UNDER THIS
TROUGH PATTERN, NORTHWEST FLOW ACROSS THE NORTHERN ROCKIES WILL
ALLOW IMPULSES TO QUICKLY MOVE SOUTH AND EAST INTO THE NORTHERN
PLAINS. HIGH PRESSURE WILL QUICKLY BUILD BEHIND THE APPARENT COLD
FRONT THAT IS OFFSHORE BY WEDNESDAY AFTERNOON/EVENING.
THE NCEP/NON-NCEP MODELS INCLUDING ENSEMBLE MEANS ARE IN GOOD
AGREEMENT WITH THE TIMING AND INTENSITY DURING THIS TIME.
STRONGER SHORTWAVE DROPPING THROUGH ROCKIES INTO THE SOUTHERN
PLAINS WEDNESDAY PM-SATURDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z ECMWF/ECMWF MEAN/CMC/UKMET
CONFIDENCE: BELOW AVERAGE
MODELS CONTINUE TO BE IN DISAGREEMENT WITH REGARDS TO THE PATTERN
CHANGES SET FOR LATE WEDNESDAY INTO THE WEEKEND. THERE IS A CLEAR
DICHOTOMY BETWEEN THE NCEP AND NON-NCEP MODELS THAT HAS LED TO
VASTLY DIFFERENT SYNOPTIC FEATURES AND THUS QPF PLACEMENT AND
INTENSITY.
NCEP MODEL (GFS/NAM) OUTPUT CONTINUES TO PROGRESS A TROUGH EAST
WITH MID-LEVEL VORTICITY CLEANLY ROUNDING THE TROUGH AXIS.
MEANWHILE, THE NON-NCEP MODELS (EC/UKMET/CMC) CALVES OFF A
SHORTWAVE FROM THE MAIN TROUGH AXIS WHICH IS GENERATING A
MID-LEVEL LOW INTO THE DESERT SOUTHWEST. AS A RESULT, THE NCEP
MODELS ARE PRODUCING A MORE AMPLIFIED TROUGH PATTERN THAT WILL
GENERATE A MORE PROGRESSIVE COLD FRONT THROUGH THE CENTRAL US AND
SURFACE LOW OFF THE GULF COAST REGION BY EARLY FRIDAY. CONVERSELY,
THE NON-NCEP MEMBERS ARE DEVELOPING A STRONG AND DEEP SURFACE LOW
ACROSS NM/TX WHICH IS SLOW TO PROGRESS EASTWARD THROUGH THE
PERIOD. THIS PIECE OF ENERGY BREAKING OFF THE MAIN TROUGH WILL
LEAD TO A QUICKER NORTHERLY STREAM AND SURFACE FRONT THROUGH THE
GREAT LAKES AND NORTHEAST DURING THE DAY FRIDAY.
IN OBSERVING THE RUN-TO-RUN CONTINUITY AMONG THE MODELS, IT
APPEARS THEY ARE ALL FAIRLY CONSISTENT. THIS IS MAKING IT A
CHALLENGE IN DETERMINING WHICH MODEL MAY BE THE BEST CHOICE
THROUGH DAY 3. HOWEVER, WHEN DIVING INTO THE ENSEMBLE MEANS, IT
APPEARS THE GEFS ILLUSTRATES A TREND TOWARD THE NON-NCEP
SOLUTIONS, SLOWING THE PROGRESSION OF THE TROUGH WITH A BIT MORE
INTERACTION WITH THE MID-LEVEL IMPULSES. ALSO, THE 12Z GFS
COMPARED TO THE 06Z SHOW SOME SIGNS OF SLOWING AS WELL, WHICH HAS
BEEN QUITE SUBTLE OVER THE PAST COUPLE OF RUNS. THE 12Z NAM ALSO
SLOWED. BASED ON THIS AND THE FACT THE THE 00Z ECMWF HAS DEEPENED
THE SURFACE/MID-LEVEL LOW OVER THE PAST COUPLE OF CYCLES, WITH THE
EC MEAN STAYING VERY CONSISTENT, FEEL THERE IS NO EVIDENCE TO
CHANGE THE BLEND AT THIS POINT.
THE WPC PREFERENCE REMAINS FOR A HEAVY WEIGHT TOWARD THE NON-NCEP
GUIDANCE, WITH MOST OF THE WEIGHT TOWARD THE ECENS MEAN WHICH IS A
GOOD COMPROMISE UNTIL FORECAST CONFIDENCE INCREASES AND MODEL
SPREAD LOWERS.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
PAGANO
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