839
FXUS10 KWNH 140625
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
224 AM EDT SUN JUN 14 2020
VALID JUN 14/0000 UTC THRU JUN 17/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..CLOSED LOW DEVELOPING IN SOUTHERN APPALACHIANS MON/TUES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
07Z UPDATE: LITTLE ADJUSTMENTS, SUCH A NORTHWARD SHIFT,EVER SO
SLIGHTLY BY DAY 3 IN THE ECMWF AND CMC, SUGGEST STRONGER OVERALL
AGREEMENT AND SUPPORT OF CONTINUED GENERAL MODEL BLEND PREFERENCE
AT ABOVE AVERAGE CONFIDENCE.
---PRIOR DISCUSSION---
GOES-E WV DEPICTS THE A SMALL COMPACT SHORTWAVE OVER LOWER LAKE
MICHIGAN AND THIS IS THE FEATURE THAT WILL DESCEND THROUGH THE
OHIO VALLEY SLOWLY AND EXPAND INTO THE FAIRLY STATIC CLOSED LOW
ACROSS THE SOUTHEAST THROUGH THE EARLY PORTION OF NEXT WEEK.
OVERALL, DIFFERENCES APPEAR TO BE GETTING SMALLER, THOUGH THE
ECMWF/CMC ARE BOTH A BIT SOUTH AND EAST OF THE NAM/GFS WITH THE
UKMET SPLIT BETWEEN. OVERALL, THE DIFFERENCES WILL BE DRIVEN BY
MESOSCALE AND CONVECTIVE PROCESSES THAT CAN BE HANDLED WITHIN A
GENERAL MODEL BLEND. CONFIDENCE IS ABOVE AVERAGE
...INTERACTION OF SHORTWAVE LIFTING THROUGH SW CANADA WITH A
CLOSED LOW ADVECTING ONSHORE WASHINGTON SUNDAY...
..SECONDARY CLOSED LOW MOVING INTO THE NORTHWEST TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 16.00Z
00Z ECMWF/CMC/NAM THEREAFTER
CONFIDENCE: ABOVE AVERAGE TRANSITIONING TO AVERAGE AFTER 48HRS
07Z UPDATE: THERE WAS A SLIGHT TRENDING TOWARD A DEEPER SOLUTION
BY THE 00Z ECWMF AND CMC, NEARING THE NAM TO PERHAPS SUGGEST SOME
MINOR INCLUSION AT THE END OF DAY 2 INTO AND THROUGH DAY 3.
HOWEVER, THIS ONLY MAKES THE DIFFERENCE OF THE FASTER GFS EVEN
MORE STARK. THE 00Z UKMET REMAINS AMPLIFIED BUT HAS SLID EAST A
BIT AWAY FROM THE NAM AND NOW ECMWF/CMC. AS SUCH WILL ADD THE NAM
AT LOWER WEIGHT TO THE PREFERENCE AFTER 16.00Z WITH CONFIDENCE
REMAINING AVERAGE AFTER 48HRS.
---PRIOR DISCUSSION---
THREE MAIN SHORTWAVE FEATURES WILL HELP DEFINE A LARGER SCALE GYRE
SET-UP THAT DEVELOPS ACROSS SW CANADA INTO THE PACIFIC NORTHWEST
AND NORTHERN US ROCKIES ACROSS THE NEXT FEW DAYS. THE INITIAL
SHORTWAVE THAT EMERGED FROM CA IS ADVANCING THROUGH THE GREAT
BASIN AND ELONGATING THE CLOSED LOW ALONG WA COAST/VANCOUVER
ISLAND AT THIS TIME. THE BINARY INTERACTION HAS STARTED TO BECOME
MUCH MORE FOCUSED AND AGREED UPON THOUGH THERE REMAINS SOME MINOR
MODEL SPREAD AS THE LEAD SHORTWAVE AMPLIFIES ACROSS SW CANADA AND
PRESSES THE FRONTAL ZONE OUT OF THE HIGH PLAINS INTO THE NORTHERN
PLAINS THROUGH MONDAY. THE 00Z GFS IS STILL A TAD FASTER, AND
THEREFORE TIGHTER/WEST WITH THE AMPLIFYING SHORTWAVE BUT OVERALL
THE PLACEMENT/TIMING OF THE SYNOPTIC FEATURES HAVE RESOLVED TO
SUPPORT A GENERAL MODEL BLEND THROUGH 48HRS, INCLUDING THE
ACCELERATION OF THE OLDER CLOSED LOW MOVING THROUGH THE NW INTO
THE HIGH PLAINS MONDAY.
THEREAFTER, THE MODEL SPREAD BEGINS TO INCREASE WITH THE APPROACH
OF THE NEXT SHORTWAVE OUT OF THE NORTH PACIFIC. THIS IS A
COMPACT SHORTWAVE/CLOSED LOW, THAT IS ACTUALLY QUITE PROGRESSIVE
THROUGH THE GULF OF AK. A SMALL TIMING WOBBLE WITHIN THE BROADER
CYCLONIC FLOW ON MONDAY, WILL HELP TO KICK THE NOSE OF THE JET
THROUGH THE PACIFIC NW AND HELP TO EXPAND THE LARGER
GYRE/INTERACTION WITH THE SW CANADA SYSTEMS' ENERGY. THIS WILL
ALSO SUPPORT A STRONG SURFACE WAVE RESPONSE TUESDAY ACROSS WY INTO
THE NORTHERN PLAINS, WITH THE BULK/CORE OF THE CLOSE LOW STILL
REMAINING UPSTREAM MAINTAINING/DIGGING THE WESTERN TROF BY 00Z
WED. THE 00Z GFS SHOWS SOME BIAS OF PRESSING THE INITIAL
HEIGHT-FALLS OUT FAST, LEADING TO A EASTWARD SHIFT OF THE FRONTAL
ZONE ACROSS THE PLAINS AS WELL AS AN ACCELERATION OF THE SURFACE
WAVE NORTH INTO CANADA LATER IN THE DAY. THIS SEEMS TOO
AGGRESSIVE AND IN LINE WITH TYPICAL NEGATIVE BIAS. THE 00Z NAM
AND 12Z UKMET ARE A BIT SLOWER BUT ALSO MUCH MORE AMPLIFIED
DIGGING THE TROF THROUGH THE SNAKE RIVER PLAINS INTO THE NORTHERN
ROCKIES AT THE SAME TIME, WHILE THE ECMWF/CMC ARE MORE MIDDLE
GROUND WITHIN THE ENSEMBLE SUITE AND MORE IN-LINE WITH THE FLOW
PATTERN/TIMING IN INTERACTION WITH THE PRECURSORY WAVE. AS SUCH
WILL FAVOR THE 00Z ECMWF/CMC OVER THE GFS/NAM/UKMET AFTER 16.00Z
(48HRS). CONFIDENCE IS ABOVE AVERAGE PRIOR TO 16.00Z BUT BECOMING
AVERAGE THEREAFTER GIVEN UNCERTAINTY IN MAGNITUDE OF SHORTWAVE
INTERACTION PLACEMENT THROUGH COMPLEX TERRAIN IN A VERY
PROGRESSIVE FLOW REGIME.
GALLINA
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