118
FXUS10 KWNH 201840
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
238 PM EDT MON JUL 20 2020
VALID JUL 20/1200 UTC THRU JUL 24/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..NORTHERN TIER OF THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND...THROUGH 48 HOURS
12Z ECMWF/GEFS AND 00Z ECENS BLEND...AFTER 48 HOURS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
FAST FLOW ATOP AN EXPANSIVE RIDGE WILL PERSIST ACROSS THE NORTHERN
TIER OF THE CONUS GOING THROUGH THE MIDDLE OF THE WEEK. EMBEDDED
WITHIN THIS FLOW, A SERIES OF WEAK TO MODERATE SHORTWAVES WILL
TRAVERSE WEST TO EAST, CAUSING AT LEAST SUBTLE AMPLIFICATION OF
TROUGHS INTO THE RIDGE TO THE SOUTH. THE MODELS ARE IN GOOD
AGREEMENT FOR MOST OF THE PERIOD, BUT BY THURSDAY THE 12Z GFS IS A
TAD STRONGER AND FASTER WITH ITS SHORTWAVE EVOLUTION ACROSS THE
PACIFIC NORTHWEST AND THE ENERGY EXITING THE GREAT LAKES AND
MOVING INTO THE NORTHEAST. ALSO THE 12Z UKMET APPEARS TO BE A TAD
TOO STRONG AND TOO FAR SOUTH WITH ITS SURFACE LOW CROSSING AREAS
OF THE LOWER GREAT LAKES AND NORTHEAST WEDNESDAY AND THURSDAY. A
GENERAL MODEL BLEND SHOULD SUFFICE THROUGH ABOUT 48 HOURS, BUT
THEREAFTER, A SOLUTION WEIGHTED TOWARD THE 12Z ECMWF/GEFS MEAN AND
00Z ECENS MEAN WILL BE PREFERRED GIVEN BETTER MODEL CLUSTERING.
THE 12Z NAM AND 12Z CMC ARE ALSO AT LEAST CLOSE TO THIS CONSENSUS.
..CALIFORNIA/SOUTHWEST U.S
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-GFS BLEND
CONFIDENCE: AVERAGE
A MID-LEVEL TROUGH AND EMBEDDED CLOSED LOW IS EXPECTED TO ADVANCE
TOWARD THE CENTRAL CA COAST BY TUESDAY AND THEN MOVE INLAND BY
LATE WEDNESDAY. MEANWHILE, AHEAD OF THIS ENERGY, THERE WILL BE A
SEPARATE MID-LEVEL TROUGH AXIS AND A MORE COMPACT CLOSED LOW
CIRCULATION THAT EVOLVES BY TUESDAY OVER THE LOWER CO RIVER
VALLEY. THIS WILL THEN LIFT NORTH AND NORTHEAST WITH TIME THROUGH
THE EASTERN GREAT BASIN AND THEN THE CENTRAL ROCKIES GOING THROUGH
WEDNESDAY AND THURSDAY. THE MODELS ARE IN GOOD AGREEMENT WITH THE
BROADER MASS FIELD EVOLUTION OF BOTH FEATURES OF INTEREST, HOWEVER
THE 12Z GFS DOES APPEAR TO BE A TAD TOO PROGRESSIVE. THE 00Z ECENS
MEAN DID FAVOR THE SLIGHTLY SLOWER CONSENSUS, ALTHOUGH THE NEW 12Z
GEFS MEAN IS A BIT MORE PROGRESSIVE LIKE THE GFS. FOR NOW, A
NON-GFS BLEND WILL BE PREFERRED WITH BOTH SYSTEMS.
IT IS WORTH NOTING THAT THIS ENERGY OVER THE SOUTHWEST COUPLED
WITH AN INFLUX OF DEEPENING MONSOONAL MOISTURE FROM NORTHERN
MEXICO AND RIO GRANDE VALLEY IS EXPECTED TO HELP DRIVE AN UPTICK
IN THE COVERAGE AND INTENSITY OF MONSOONAL CONVECTION ACROSS THE
FOUR CORNERS REGION THROUGH THE MIDDLE OF THE WEEK.
..MID-LEVEL EASTERLY WAVES IMPACTING THE SOUTHERN CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
A SERIES OF MID-LEVEL TROUGHS/EASTERLY WAVES WITH AT LEAST A
MODEST SURFACE REFLECTION WILL MOVE ACROSS THE GULF COAST REGION
THROUGH MIDWEEK. OUTSIDE OF THE WEAKER 12Z UKMET WITH THIS WAVE
ACTIVITY, THE REMAINING GUIDANCE IS IN REASONABLY GOOD AGREEMENT
IN TRACKING THIS ENERGY ACROSS THE GULF OF MEXICO AND INTO TEXAS.
IT SHOULD BE NOTED THAT BY THURSDAY THE GUIDANCE HAS BEEN TRENDING
TOWARD AND COMING INTO AGREEMENT ON THERE BEING AT LEAST A WEAK
AREA OF LOW PRESSURE OVER THE WESTERN GULF OF MEXICO. BASED ON THE
LATEST MODEL CLUSTERING AND SPREAD, A NON-UKMET BLEND WILL BE
PREFERRED.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
THIS PRODUCT WILL TERMINATE AUGUST 15, 2020:
WWW.WEATHER.GOV/MEDIA/NOTIFICATION/PDF2/SCN20-58PMDHMD_TERMINATION.
ORRISON
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