030
FXUS10 KWNH 130424
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1223 AM EDT SAT JUN 13 2020
VALID JUN 13/0000 UTC THRU JUN 16/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..EXITING TROUGH ACROSS MID-ATLANTIC TO NORTHEAST
..CLOSED LOW DEVELOPING IN SOUTHERN APPALACHIANS MON/TUES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-GFS BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
LINGERING SHORTWAVE ENERGY OVER THE LOWER GREAT LAKES WILL
CONSOLIDATE IN THE MID-LEVELS LATER TODAY INTO EARLY SUNDAY AND
START TO SLIDE NORTHEAST INTO SE CANADA BY MONDAY, WITH LITTLE
FANFARE OR MODEL DIFFERENCES.
THE TRAILING EDGE OF THE LONGER WAVE PATTERN UPSTREAM ACROSS THE
UPPER GREAT LAKES WITH A SMALL 90KT NW-SE ORIENTED JET WILL
AMPLIFY INTO A SMALL BUT COMPACT WAVE THROUGH THE MIDWEST LATER
TODAY AND DROP INTO THE CENTRAL OHIO VALLEY. GUIDANCE HAS
FINALLY COME INTO STRONG AGREEMENT WITH THE PLACEMENT/MAGNITUDE OF
THE WAVE THROUGH 48HRS AS IT PIVOTS/STALLS IN S OH/E KY/W WV,
ENOUGH TO HAVE ABOVE AVERAGE CONFIDENCE IN A GENERAL MODEL BLEND
THROUGH THIS PERIOD. AFTERWARDS, THE MODELS SPREAD AS THE WAVE
EXITS THE TIGHT LOOP EXPANDING INTO A BROADER CLOSED LOW ACROSS
THE SOUTHERN APPALACHIANS INTO THE COASTAL PLAIN OF GA/SC. THE
00Z GFS IS SLOWEST TO WOBBLE OUT AND DRAWS STRONGER ENERGY FROM
THE NORTHERN STREAM TO DELAY THIS FURTHER, LEADING TO AN OVERALL
NORTHWARD ORIENTATION TO THE REST OF THE GLOBAL/ENSEMBLE SUITE.
THE 18Z GEFS SHOWS SOME CLOSENESS INITIALLY BUT BY 84HRS IS
FURTHER SOUTH AND CLOSER TO THE ECMWF/NAM. THE 12Z UKMET/CMC ARE
A BIT EAST OF THE ECMWF/NAM BUT THE EVOLUTION/PLACEMENT AND SHAPE
ALL SUGGEST A NON-GFS BLEND IS PREFERABLE AT SLIGHTLY ABOVE
AVERAGE CONFIDENCE.
IT SHOULD BE NOTED THAT THE 00Z NAM IS A BIT STRONG WITH
RETROGRADING A LOW LEVEL WAVE THROUGH THE CAROLINAS AND TIGHTENING
THE OVERALL LOW LEVEL FLOW FOR A STRONG QPF SIGNAL...THIS IS
LIKELY OVER-INFLATED BUT GIVEN THE MODEL RESOLUTION AND CAPABILITY
FOR RESOLVING SOME MESOSCALE MOISTURE/INSTABILITY BETTER THAN THE
GLOBAL GUIDANCE...IT SHOULD BE INCORPORATED BUT WITH SOME CAUTION
GIVEN THE BIAS TO OVER-STRENGTHEN SYSTEMS ESPECIALLY IN THE LATE
DAY 2 TO DAY 3 PERIOD.
...LONGWAVE TROUGH OFF THE WEST COAST AND SHORTWAVE LIFTING
ONSHORE CALIFORNIA BY THE WEEKEND, INTERACTING THROUGH NORTHERN
ROCKIES/SW-CENTRAL CANADA SUNDAY-TUES...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-GFS BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
A TIGHT SHORTWAVE IS LIFTING NORTH THROUGH CA AT THIS TIME, ALONG
THE EASTERN SIDE OF A CLOSED LOW NEAR VANCOUVER ISLAND. THE 00Z
GFS CONTINUES TO BE SLIGHTLY FASTER LIFTING INTO SW CANADA
RELATIVE TO THE OTHER GUIDANCE AND IN DOING SO FINDS A MORE
FAVORABLE ENVIRONMENT/POSITION RELATIVE TO THE UPSTREAM CLOSED LOW
TO RAPIDLY DEEPEN AND BECOME THE DOMINANT CIRCULATION IN THE
BINARY INTERACTION RELATIVE TO THE REST OF THE GLOBAL GUIDANCE
SUITE. T THIS DOESN'T SEEM TO NEGATIVELY AFFECT THE
TIMING/STRENGTH OF THE REMAINDER OF THE CLOSED LOW AS IT SWING
AROUND THE BASE OF THE LARGER SCALE CLOSED LOW, AS WELL AS, THE
EASTWARD PROGRESSION OF THE FRONTAL ZONE INTO THE NORTHERN PLAINS
WHERE SPREAD IS SMALL. STILL THE GFS IS NOT GENERALLY FAVORED
OUTSIDE OF THE CONUS, WHERE A MORE ELONGATED WEST TO E SHEARED
TROF IS PREFERRED FROM THE UKMET/ECMWF/NAM THAN THE MORE COMPACT
CMC, BUT ONLY IN WEIGHTING WITHIN A NON-GFS BLEND. CONFIDENCE IS
SLIGHTLY ABOVE AVERAGE.
...NEXT CLOSED LOW/EMBEDDED SHORTWAVES ENTERING PACIFIC NW
MON-TUES...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND; WEIGHT HEAVIER TO 12Z ECMWF/CMC
CONFIDENCE: AVERAGE
UPSTREAM, A CLOSED LOW IS DEVELOPING IN THE WESTERN GULF OF AK
LATER TODAY INTO SUNDAY, THOUGH REMAINS FAIRLY PROGRESSIVE IN
NATURE. THERE IS A FORECAST SLOW DOWN AS THE DEEPER CYCLONE
OCCLUDES/WOBBLES WEST OF HAIDA GWAII/CHARLOTTE ISLAND. THIS WILL
ALSO ALLOW FOR RETURN SUBTROPICAL SHORTWAVE ENERGY TO PRESS
EASTWARD AND BRING SOLID DPVA INTO THE PACIFIC NW BY MIDDAY
HELPING TO BROADEN THE LARGER SCALE PATTERN INTO A DUAL LOBE
GLOBAL SCALE GYRE FROM THE EASTERN GULF OF AK THROUGH MUCH OF
WESTERN CANADA (SEE SYSTEM IN ABOVE SECTION). THE TYPICALLY
FASTER SOLUTIONS OF THE GFS/UKMET AND NAM CONTINUE TO TREND FASTER
BUT NOW SUGGEST THE MAIN BODY OF THE WAVE WILL DROP THROUGH THE
MOUTH OF THE COLUMBIA RIVER AT 84HRS. THIS IS OPPOSED BY THE
ECMWF/CMC WHICH CONTINUE TO LAG AND FAVOR MORE OF AN AMPLIFICATION
OF THE SUBTROPICAL SHORTWAVE RELATIVELY SPEAKING TO THE
GFS/UKMET/NAM. THE EFFECTS ON QPF ARE ACTUALLY MINIMAL, THOUGH
THE MASS FIELDS ARE SHOWING INCREASED SPREAD LEADING TO INCREASED
CONFIDENCE THERE, BUT LESSER SO ON THE MASS FIELD SIDE. THE
FASTER TREND HAS BEEN NOTED THROUGH MULTIPLE CYCLES OF THE
ENSEMBLES, YET THIS FASTER SOLUTION IS ALSO ALIGNED WITH THE
GENERAL NEGATIVE BIAS OF THESE MODELS RELATIVE TO THE ECMWF/CMC.
SO AT THIS TIME WILL KEEP WITH MORE CONTINUITY OVER THE TREND, AND
PREFER A HIGHER WEIGHTING TO THE ECMWF/CMC; HOWEVER, LEAVING THE
DOOR OPEN TOWARDS A POTENTIAL SHIFT WITH THE NEW 00Z ECMWF/CMC
SOLUTIONS. AS SUCH A GENERAL MODEL BLEND IS PREFERRED BUT
WEIGHTED MORE HEAVILY TOWARD CONTINUITY/ECMWF/CMC.
GALLINA
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