603
FXUS10 KWNH 241832
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
132 PM EST TUE DEC 24 2019
VALID DEC 24/1200 UTC THRU DEC 28/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PREFERENCE AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..OVERALL PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/NAM/CMC AND **00Z** ECMWF
EXCEPTION: REMOVE 12Z NAM IN RED RIVER VALLEY OF NORTH ON
WED/THURS...
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
19Z UPDATE: THE 12Z CMC/UKMET BOTH TRENDED SLOWER AND THEREFORE A
BIT SHARPER OVERALL WITH THE NORTHERN STREAM JET ENERGY ENTERING
THE PACIFIC NORTHWEST LATE THURSDAY INTO FRIDAY...THOUGH THE UKMET
IS MUCH SHARPER AND EVEN SLOWER THAN THE INITIAL PREFERENCE
(GFS/NAM/00Z ECMWF), SO MAY BE LESS FAVORABLE BY THE 28.00Z.
SIMILARLY THE ECMWF TRENDED A BIT SLOWER AND THEREFORE SHARPER
WITH THIS TROF AS WELL; HOWEVER, THE CLOSED LOW WAS MUCH WEAKER
AND THEREFORE FASTER DRAWING NORTH OUT OF THE FOUR CORNERS A BIT
TOO FAST. THIS APPEARS TO BE A ONE OFF RUN FOR THE ECMWF,
ESPECIALLY WITH THE UKMET/CMC TRENDING A BIT MORE LIKE THE GFS/NAM
OR BETTER YET THE 00Z ECMWF. AS SUCH, WILL CONTINUE TO REMOVE
THE 12Z NAM ACROSS THE RED RIVER VALLEY THURSDAY...BUT WILL FAVOR
A 12Z GFS/CMC/NAM AND 00Z ECMWF BLEND FOR THE REMAINDER OF THE
CONUS AT SLIGHTLY ABOVE AVERAGE CONFIDENCE.
---PRIOR DISCUSSION---
A DEEP LATITUDE, BUT NARROW TROF ACROSS THE INTERMOUNTAIN WEST IS
EXPECTED TO EXPAND/BROADEN TO A GLOBAL SCALE TROF WITH THE
APPROACH OF SHORTWAVE ENERGY OUT OF THE GULF OF ALASKA LATE
TUESDAY INTO WED. THE LEAD SHORTWAVE ENERGY CURRENTLY ACROSS THE
DESERT SOUTHWEST WILL LIFT NORTHEASTWARD GENERALLY WEAKENING
THROUGH THE EXPANDING LARGER SCALE TROF BUT A WEAKER KICKER WAVE
IN THE SOUTHERN STREAM WILL LIFT QUICKLY BEHIND AND UNDER
INFLUENCE OF THE BROAD DIFFLUENT PATTERN ALOFT AMPLIFIES TO A
RELATIVELY DRY CYCLONE ACROSS THE NORTHERN RED RIVER. MODELS
CONTINUE TO CONSOLIDATE IN PLACEMENT AND STRENGTH, THOUGH THE 12Z
NAM CONTINUES TO BE STRONGEST/COMPACT BY LATE THURS...AND SHOULD
BE TEMPERED OR REMOVED IN THE LOCAL AREA BLEND.
AFTER ITS PASSAGE, THE ACTIVE GULF OF ALASKA STREAM, DRIVES
SHORTWAVE ENERGY ACROSS SOUTHERN CANADA. THE 00Z CMC IS
PARTICULAR (AND UNCHARACTERISTICALLY FAST) LEADING TO LESS
SOUTHWARD DIGGING WHICH IS NOT SUPPORTED THROUGH THE ENSEMBLE
SUITE. THE 00Z UKMET, WHILE A BIT LESS FLAT, IS ALSO PROGRESSIVE
AND SHOULD BE REMOVED FROM THE SUITE. THE 12Z NAM, ALONG WITH THE
12Z GFS/00Z ECMWF ARE MORE IN LINE WITH THE OVERALL TREND WITHIN
THE ENSEMBLE SUITE DEPICTING A SHARPENING ACROSS THE NORTHERN HIGH
PLAINS TOWARD 28.00Z. SO WOULD FAVOR THOSE WITHIN A BLEND AFTER
THE INITIAL SHORTWAVE ON WED.
ALONG THE WESTERN SIDE OF THE BROADENING WESTERN LARGE SCALE TROF,
A STRONG MERIDIONAL JET STREAK AND ASSOCIATED SHORTWAVE DIG
PARALLEL TO THE WEST COAST EVENTUALLY CLOSING INTO A COMPACT
CLOSED LOW ALONG THE CENTRAL CA COAT BY 26.12Z. THERE IS SOLID
MODEL AGREEMENT IN THIS EVOLUTION THROUGH THIS TIME PERIOD, BUT
THE 00Z CMC EVENTUALLY DIGS TOO FAR SOUTH RELATIVE TO THE SUITE
AND BECOMES LESS FAVORABLE AFTER 26.12Z. THEREAFTER, AS THE
CLOSED LOW WEAKENS AND ROLLS THROUGH THE SOUTHWEST, THERE IS A
TYPICAL TIMING DIFFERENCE THAT EMERGES WITH THE 12Z GFS/00Z UKMET
AND LESSER SO THE 12Z NAM (TRENDED A BIT SLOWER WITH THIS
ITERATION) FASTER INTO THE SOUTHERN PLAINS BY 00Z SAT,
INTERSECTING WITH RETURN MOISTURE FURTHER EAST THAN THE
ECMWF/ECENS SOLUTIONS. THIS LOOKS LIKE A MORE TYPICAL
ORIENTATION/PREDICTABLE VARIATION TO SUPPORT THE SLIGHTLY SLOWER
SOLUTION (MORE OF A 2/3RD EC CAMP & 1/3 GFS CAMP BLEND) THAT
VERIFIES WELL AND SUBSEQUENT RUNS TREND TOWARD. AS SUCH
CONFIDENCE IS SLIGHTLY ABOVE AVERAGE OVERALL.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
GALLINA
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