964
FXUS10 KWNH 240445
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1240 AM EDT SUN MAY 24 2020
VALID MAY 24/0000 UTC THRU MAY 27/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SHORTWAVE TROUGH CROSSING THE GREAT LAKES THROUGH SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
A RATHER COMPACT MID TO UPPER-LEVEL LOW CENTER CROSSING THE
MIDWEST THIS EVENING WILL BE ADVANCING ACROSS THE GREAT LAKES
REGION ON SUNDAY AND WEAKENING WITH TIME AS IT TRACKS OVER THE
TOP OF A STRENGTHENING DEEP LAYER RIDGE OVER THE SOUTHEAST U.S. ON
MONDAY, A WEAK REMNANT OF THIS ENERGY WILL CROSS THROUGH NORTHERN
NEW ENGLAND. THE MODELS ARE IN GOOD AGREEMENT WITH THIS SYSTEM,
AND SO A GENERAL MODEL BLEND WILL BE PREFERRED.
DEEP UPPER TROUGH CROSSING THE INTERMOUNTAIN WEST TO THE PLAINS
LEAD SHORTWAVES CROSSING THE SOUTHERN PLAINS SUNDAY/MONDAY
CLOSED LOW FORMATION OVER THE SOUTHERN PLAINS BY TUESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z ECMWF/ECENS MEAN AND 18Z GEFS MEAN
CONFIDENCE: AVERAGE
THE LATEST GUIDANCE SHOWS VERY GOOD AGREEMENT IN BRINGING A NEW
LARGE SCALE UPPER TROUGH AND ASSOCIATED CLOSED LOW IN ACROSS THE
INTERMOUNTAIN WEST THROUGH THE WEEKEND. BY MONDAY, THE MODELS
SUPPORT THIS DEEP TROUGH EDGING TOWARD THE PLAINS WITH ONE CLOSED
LOW CENTER EXITING THE NORTHERN ROCKIES AND CROSSING THE NORTHERN
HIGH PLAINS. MEANWHILE, A SECOND CLOSED LOW WILL BE ATTEMPTING TO
FOCUS OVER THE CENTRAL ROCKIES, AND BY TUESDAY THE GUIDANCE IS IN
REASONABLY GOOD AGREEMENT ON THE IDEA OF A NEW CLOSED LOW BECOMING
WELL-DEFINED OVER THE SOUTHERN PLAINS.
LEADING UP TO THIS CLOSED LOW EVOLUTION OVER THE SOUTHERN PLAINS,
THERE WILL BE A PAIR OF SHORTWAVE TROUGHS, ONE ON SUNDAY AND ONE
ON MONDAY, THAT WILL ROUND THE BASE OF THE LARGER SCALE TROUGH AND
LIFT NORTHEAST ACROSS THE SOUTHERN PLAINS. THE FIRST SHORTWAVE IS
EXPECTED TO EVOLVE OUT OF THE MCS ACTIVITY CURRENTLY IMPACTING
AREAS SOUTH-CENTRAL TX AND THE MIDDLE RIO GRANDE VALLEY. THE
SECOND AND MORE DOMINANT SHORTWAVE IS CURRENTLY SHOWING UP VERY
DISTINCTLY ACROSS THE SOUTHWEST U.S. AND NORTHWEST MEXICO IN
GOES-WV SATELLITE IMAGERY, AND IS MOVING STEADILY OFF TO THE EAST.
THE 00Z NAM AND 00Z GFS ARE A TAD STRONGER THAN THE 12Z NON-NCEP
MODELS WITH THE FIRST SHORTWAVE, WHICH IS LIKELY A REFLECTION OF
THEIR 00Z SAMPLING/CYCLING OF THE ONGOING CONVECTION. THIS ENERGY
WILL LIFT NORTHEAST THROUGH SUNDAY NIGHT TOWARD THE LOWER MS
VALLEY AS THE SECOND UPSTREAM SHORTWAVE TROUGH ARRIVES AND
ULTIMATELY FOSTERS THE UPPER LOW DEVELOPMENT OVER THE SOUTHERN
PLAINS BY TUESDAY.
WITH THE SECOND SHORTWAVE, THE 00Z NAM AND 00Z GFS ARE ALSO A TAD
STRONGER THAN THE NON-NCEP MODELS, WITH THE GFS ALSO BEING A TAD
ON THE FASTER SIDE OF THE GUIDANCE. THE 12Z UKMET IS PERHAPS A BIT
TOO WEAK WITH THE SECOND SHORTWAVE TROUGH WHICH RESULTS ULTIMATELY
IN A SOMEWHAT WEAKER UPPER LOW EVOLUTION. THE 12Z CMC BY THE END
OF THE PERIOD IS ALSO SEEN AS BEING A BIT TOO FAR NORTH WITH ITS
UPPER LOW. MEANWHILE, THE 00Z NAM APPEARS TO BE A TAD TOO SLOW IN
EJECTING THE DEEPER LAYER TROUGH AND CLOSED LOW OFF TO THE EAST BY
THE END OF THE PERIOD. THE 12Z ECMWF, 12Z ECENS MEAN, AND 18Z GEFS
MEAN ARE WELL CLUSTERED WITH THE UPPER LOW TUESDAY THROUGH EARLY
WEDNESDAY, AND ALSO WITH THEIR CORRESPONDING SURFACE WAVE
REFLECTIONS FOR WHICH THE NAM/CMC CAMP SUGGESTS STRONGER WAVE
ACTIVITY LIFTING NORTH ACROSS KS, AND THE GFS/UKMET CAMP WITH LOW
PRESSURE MORE CONCENTRATED OVER AREAS OF SOUTHWEST OK AND
NORTHWEST TO NORTH-CENTRAL TX. A MORE ELONGATED AXIS OF LOW
PRESSURE IS LIKELY TO EVOLVE WITH MULTIPLE WAVES THAT LIFT ACROSS
CENTRAL/EASTERN TX AND NORTHWARD UP ACROSS EASTERN OK AND EASTERN
KS LATE TUESDAY THROUGH EARLY WEDNESDAY AS THIS IS LIKELY WHERE A
SLOW-MOVING OR QUASI-STATIONARY FRONT SHOULD BE POSITIONED. WILL
PREFER A BLEND OF THE ECMWF, ECENS MEAN AND GEFS MEAN AT THIS
POINT WITH THE SHORTWAVES AND CLOSED LOW EVOLUTION.
MID-LEVEL TROUGH IMPACTING FLORIDA EARLY IN THE WEEK
WEAK SURFACE LOW OVER EAST-CENTRAL GULF OF MEXICO
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-UKMET BLEND...FOR THE MID-LEVEL TROUGH
00Z NAM/12Z ECMWF BLEND...FOR THE GULF SURFACE LOW
CONFIDENCE: AVERAGE
AS A STRONG SUBTROPICAL RIDGE BUILDS OVER THE SOUTHEAST AND THE
MID-ATLANTIC REGION GOING INTO THE BEGINNING OF THE WEEK, THERE
WILL BE A MID-LEVEL TROUGH AXIS LIFTING NORTH FROM THE YUCATAN
PENINSULA AND WESTERN CARIBBEAN SEA TO THE SOUTHERN GULF OF
MEXICO. THIS ENERGY IS EXPECTED TO ELONGATE AND CROSS AREAS OF
SOUTHERN FLORIDA BY LATE MONDAY AND INTO TUESDAY. THERE IS ALSO
GROWING SUPPORT FOR A WEAK AREA OF LOW PRESSURE TO FORM ALONG AN
INVERTED SURFACE TROUGH AS WELL, WITH THE 00Z NAM, 12Z ECMWF AND A
LARGE NUMBER OF EUROPEAN AND CANADIAN ENSEMBLE MEMBERS SUGGESTING
SURFACE LOW DEVELOPMENT. THE 00Z HREF MODEL SUITE ALSO SUPPORTS
THIS AS WELL. WITH RESPECT TO THE MID-LEVEL TROUGH, THE 12Z UKMET
AGAIN REMAINS MORE SUPPRESSED WITH IT AND THIS IS A RESULT OF THE
UKMET BEING STRONGER WITH ITS SUBTROPICAL RIDGE TO THE NORTH OVER
THE SOUTHEAST U.S. THE MODEL PREFERENCE WILL BE TOWARD A NON-UKMET
BLEND WITH THE DETAILS OF THE MID-LEVEL TROUGH GIVEN DECENT MODEL
CLUSTERING SEEN OTHERWISE WITH THIS, BUT WITH THE WEAK SURFACE LOW
FEATURE OVER THE GULF OF MEXICO, A BLEND OF THE 00Z NAM AND 12Z
ECMWF WILL BE PREFERRED.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
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