724
FXUS10 KWNH 041833
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
233 PM EDT SAT JUL 04 2020
VALID JUL 04/1200 UTC THRU JUL 08/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
19Z UPDATE: THE 12Z CMC TRENDED OUT OF FAVOR FOR DAY 2/3 WITH THE
TROUGHING EXPECTED MONDAY/MONDAY NIGHT - IT'S TOO FAST AS ITS
DOWNSTREAM RIDGING IS MUCH WEAKER OVER THE NORTHERN PLAINS AND
NORTHERN PLAINS. ELSEWHERE ACROSS THE CONUS, THE REST OF THE 12Z
GUIDANCE DID NOT STRAY FROM THE OTHER DETERMINISTIC GUIDANCE
ENOUGH TO WARRANT A CHANGE TO THE MODEL BLEND PREFERENCES.
TROUGH BUILDING OVER THE NORTHEAST U.S. THIS WEEKEND
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
SHORTWAVE TROUGH ENERGY WILL SKIRT THE NORTHEAST AND NEW ENGLAND
LATE IN THE WEEKEND INTO EARLY MONDAY. MODEL AGREEMENT IS AVERAGE
TO ABOVE AVERAGE WITH THE ONLY NOTABLE DIFFERENCE SEEN COMING FROM
THE 12Z NAM WHICH IS FLATTER AND FASTER WITH THE TROUGH PASSAGE ON
MONDAY. IT'S QUICK TO PUSH THROUGH WHILE THE OTHER MODELS,
DOMINATED BY THE CMC AND GFS, OFFER A SLOWER AND CLOSED LOW
SOLUTION OFF THE GULF OF MAINE. THE UKMET AND ECMWF ARE SIMILAR
BUT A BIT MORE OPEN, BUT SHOW SIMILAR TIMING TO THE GFS/CMC. GIVEN
THESE DIFFERENCES AND HOW MUCH THE NAM IS AN OUTLIER, A NON-NAM
BLEND IS PREFERRED.
TROUGH OVER THE GULF COAST REGION
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS, 00Z ECMWF BLEND
CONFIDENCE: AVERAGE
AFTER DAYS OF WEAKNESS IN THE UPPER LEVEL RIDGE OVER THE LOWER MS
VALLEY AND SOUTHEAST, SOME GRADUAL BUILDING OF HEIGHTS IS FORECAST
OVER THE NEXT 3 DAYS, THOUGH BIG SIGNIFICANT CHANGES IN THE FLOW
ARE NOT EXPECTED. REMNANT MCVS AND CONVECTIVELY ENHANCED
SHORTWAVES WILL BE COMMON, TIED TO RESIDUAL SURFACE BOUNDARIES
FROM EARLIER CONVECTION AND MUCH OF THE QPF AND SENSIBLE WEATHER
DIFFERENCES ARE ON THE MESOSCALE LEVEL. GUIDANCE RANGES FROM THE
CORE OF THE UPPER LEVEL WEAKNESS TO BE AS FAR EAST AS GA (UKMET)
OR WEST OVER THE LOWER MS VALLEY (CMC/NAM). THE GFS/ECWMF OFFER A
COMPROMISE APPROACH AND WOULD BE A GOOD BLEND TO GO WITH GIVEN
THESE DIFFERENCES.
TROUGHING CONTINUES ACROSS THE PACIFIC NW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC BLEND
CONFIDENCE: ABOVE AVERAGE
GENERAL TROUGHING IS EXPECTED TO CONTINUE ACROSS THE PACIFIC
NORTHWEST AND NORTHERN ROCKIES THROUGH THE FORECAST PERIOD WITH A
COUPLE DIFFERENT SHORTWAVE TROUGHS MOVING THROUGH THE FLOW. ONE
CURRENTLY IS LIFTING ACROSS MONTANA WHICH IS EXPECTED TO PUSH
THROUGH INTO SOUTHERN CANADA. FOLLOWED BY BRIEF RIDGING, ANOTHER
SHORTWAVE TROUGH MOVES ONSHORE OREGON/WASHINGTON MONDAY AND MONDAY
NIGHT. OVERALL, MODEL AGREEMENT IS FAIRLY GOOD, THE NAM A BIT
DEEPER THAN THE OTHER DETERMINISTIC GUIDANCE. BUT FROM A MASS
FIELD PERSPECTIVE, A GENERAL MODEL BLEND SHOULD BE SUFFICIENT.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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