207
FXUS10 KWNH 030417
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1217 AM EDT WED JUN 3 2020
VALID JUN 3/0000 UTC THRU JUN 6/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING INITIAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
UPPER LEVEL LOW SLOWLY LIFTING INTO OKLAHOMA THAT DRIFTS EAST INTO
WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: MODERATE-HIGH
A BROAD UPPER LOW CURRENTLY CENTERED OVER EASTERN OKLAHOMA WILL
TRACK EASTWARD ACROSS ARKANSAS, AND THEN EVOLVE INTO A BROAD UPPER
LEVEL TROUGH. THE 250-500 MB TROUGH AXIS WILL EXTEND SOUTHWARD
OVER THE NORTHERN GULF OF MEXICO, AND THIS WILL BE IMPORTANT SINCE
UPPER LEVEL FLOW AHEAD OF IT WILL PLAY A ROLE IN THE FUTURE TRACK
OF TROPICAL STORM CHRISTOBAL. ALL GLOBAL GUIDANCE ARE IN CLOSE
ENOUGH AGREEMENT ON THE MAIN FEATURES TO MERIT THE USE OF A
MULTI-DETERMINISTIC MODEL BLEND.
CUT-OFF LOW LINGERING SOUTHWEST OF CALIFORNIA THROUGH THURSDAY
BEFORE EJECTING EAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 00Z FRIDAY, THEN NON-GFS
DAY 3.
CONFIDENCE: MODERATE-HIGH
A CUT OFF UPPER LOW WILL REMAIN NEARLY ANCHORED IN PLACE THROUGH
THURSDAY WEST OF THE RIDGE AXIS OVER THE SOUTHERN ROCKIES BEFORE
BEGINNING TO EJECT EAST TOWARD SOUTHERN CALIFORNIA BY THURSDAY
NIGHT AND INTO FRIDAY. SIMILAR TO YESTERDAY, THE GFS REMAINS
SLIGHTLY FASTER IN BRINGING THE CLOSED LOW EASTWARD ON FRIDAY
COMPARED TO THE OTHER GUIDANCE, AND THEREFORE THE PREFERENCE FOR
DAY 3 IS NON-GFS AT THIS TIME.
ACTIVE FLOW PATTERN ACROSS NORTHERN TIER OF U.S.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC BLEND THROUGH THURSDAY, THEN 12Z
ECMWF/UKMET/EC MEAN
CONFIDENCE: MODERATE
THE WESTERLIES ON THE NORTHERN PERIPHERY OF THE CENTRAL U.S. RIDGE
WILL REMAIN ACTIVE WITH TWO WELL-DEFINED SHORTWAVE DISTURBANCES
TRACKING EASTWARD NEAR THE U.S./CANADA BORDER THROUGH THE END OF
THE WEEK. THE FIRST DISTURBANCE IS A SHORTWAVE OVER NORTHERN
MANITOBA WHICH WILL TRACK SOUTH OF THE HUDSON BAY BY WEDNESDAY AND
BE DIRECTED ACROSS NORTHERN MAINE BY A DEEP LOW OVER LABRADOR, AND
RESULT IN A COLD FRONT STALLING OVER THE EAST-CENTRAL U.S. AND
PROVIDE A FOCUS FOR RAINFALL. THE SECOND SYSTEM, CURRENTLY OVER
ALBERTA, WILL TRACK JUST NORTH OF THE BORDER AND EVOLVE INTO AN
UPPER LOW OVER MANITOBA BY WEDNESDAY NIGHT. THIS WILL SEND A COLD
FRONT ACROSS THE NORTHERN GREAT PLAINS WEDNESDAY NIGHT AND ACROSS
THE MIDWEST BY THURSDAY.
DESPITE THE QUASI-ZONAL AND PROGRESSIVE FLOW PATTERN IN PLACE
ACROSS THE REGION, MODELS ARE IN GOOD AGREEMENT THROUGH THURSDAY,
EXCEPT FOR THE 12Z CMC WHICH SLOWED FROM THE 00Z RUN, BUT MORE
IMPORTANTLY FLATTER THAN THE REST OF THE GUIDANCE WITH EASTWARD
PROGRESSION OF THE SECOND WAVE OVER THE CANADIAN PRAIRIES STARTING
LATE WEDNESDAY. THE 00Z GFS BECOMES SLIGHTLY MORE AMPLIFIED WITH
THE SECOND WAVE BY THURSDAY EVENING ACROSS THE NORTHERN PLAINS,
AND THE NAM IS SLOWER WITH IT BY FRIDAY AS IT CROSSES THE NORTHERN
GREAT LAKES REGION.
CLOSED LOW DRIFTING SOUTH FROM GULF OF ALASKA BY FRIDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 12Z FRIDAY, THEN NON-CMC
BLEND
CONFIDENCE: MODERATE-HIGH
AN UPPER LEVEL LOW ORIGINATING OVER THE GULF OF ALASKA IS EXPECTED
TO DROP SOUTHEASTWARD, WEST OF THE BRITISH COLUMBIA COAST, AND BE
SITUATED SEVERAL HUNDRED MILES WEST OF THE WASHINGTON COAST BY
SATURDAY MORNING. EXCEPT FOR A SLIGHTLY SLOWER 12Z CMC BEYOND
FRIDAY MORNING, THERE IS ENOUGH DETERMINISTIC MODEL AGREEMENT TO
MERIT THE USE OF A GENERAL MODEL BLEND FOR THIS REGION.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
HAMRICK
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