302
FXUS10 KWNH 260433
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1231 AM EDT TUE MAY 26 2020
VALID MAY 26/0000 UTC THRU MAY 29/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SHORTWAVE CURRENTLY OVER THE NORTHERN PLAINS
RELOADING NORTHERN STREAM TROUGH OVER NORTHERN PLAINS BY WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
A SHORTWAVE TROUGH CURRENTLY OVER THE NORTHERN PLAINS WILL BE
GETTING ABSORBED INTO THE WESTERLIES ACROSS SOUTHERN CANADA BY
LATER TUESDAY. HOWEVER, BY LATER TUESDAY AND WEDNESDAY, THE MODELS
SUPPORT AMPLIFICATION OF A NEW NORTHERN STREAM TROUGH OVER
SOUTHERN CANADA AND THE NORTHERN PLAINS. THIS ENERGY SHOULD THEN
MOVE ACROSS THE UPPER MIDWEST BY THURSDAY. THIS WILL DRIVE SURFACE
LOW PRESSURE ACROSS SOUTHERN CANADA WITH A TRAILING COLD FRONT
THAT WILL BE CROSSING THE NORTHERN PLAINS AND UPPER MIDWEST. THE
MODEL SPREAD THROUGH THE PERIOD IS RATHER MODEST, AND SO A GENERAL
MODEL BLEND WILL BE PREFERRED FOR THE TIME BEING.
DEEP CLOSED LOW OVER THE SOUTHERN PLAINS AND LOWER MS VALLEY
WEAKENING TOWARD THE OH/TN VALLEYS BY FRIDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND...THROUGH 60 HOURS
NON-CMC BLEND...AFTER 60 HOURS
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE MODELS ALL AGREE IN DEVELOPING A CUT-OFF UPPER LOW OVER
NORTHERN TX BY LATE TUESDAY. THIS UPPER LOW SHOULD THEN DRIFT VERY
SLOWLY EASTWARD THROUGH NORTHEAST TEXAS BY EARLY WEDNESDAY. ON
THURSDAY, IT SHOULD CROSS THE LOWER MS VALLEY, BUT THE GUIDANCE
SUPPORTS IT BEGINNING TO SLOWLY WEAKEN AND ELONGATE
EAST-NORTHEASTWARD TOWARD THE LOWER OH/TN VALLEYS BY FRIDAY AS IT
COMES UNDER INFLUENCE OF THE NORTHERN STREAM TROUGH CROSSING THE
UPPER MIDWEST. MODEL MASS FIELD SPREAD IS MINIMAL THROUGH ABOUT 60
HOURS. AFTER 60 HOURS, THE 12Z CMC WAS SEEN AS KEEPING THE UPPER
LOW SOUTH OF THE MODEL CONSENSUS, BUT THERE IS GOOD CLUSTERING
SEEN OTHERWISE IN THE GUIDANCE TO SUPPORT THE ENERGY ADVANCING
INTO THE OH/TN VALLEY REGION BY EARLY FRIDAY. WILL PREFER A
GENERAL MODEL BLEND THROUGH 60 HOURS, AND THEN A NON-CMC BLEND
THEREAFTER.
MID-LEVEL TROUGH AND WEAK SURFACE LOWS IMPACTING FLORIDA
ENERGY LIFTING UP ACROSS THE SOUTHEAST U.S. BY WEDNESDAY/THURSDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z GFS, 12Z ECENS MEAN AND 18Z GEFS MEAN
CONFIDENCE: AVERAGE
AN UPPER-LEVEL RIDGE OVER THE SOUTHEAST U.S. WILL GRADUALLY BUILD
OUT ACROSS THE WESTERN ATLANTIC BY MIDWEEK. SOUTH AND WEST OF THE
EVOLVING RIDGE WILL BE A LOW TO MID-LEVEL TROUGH AXIS WHICH IS
EXPECTED TO LIFT NORTHWARD THROUGH THE EASTERN GULF OF MEXICO AND
THE FL PENINSULA GOING THROUGH TUESDAY. BY WEDNESDAY AND THURSDAY,
THIS ENERGY WILL BE ADVANCING NORTH THROUGH THE SOUTHEAST AND THE
SOUTHERN APPALACHIANS WITHIN DEEP LAYER SOUTHERLY FLOW SITUATED
BETWEEN THE DEEP UPPER LOW APPROACHING THE LOWER MS VALLEY AND THE
BUILDING RIDGE OVER THE WESTERN ATLANTIC. MULTIPLE WAVES OF LOW
PRESSURE ARE EXPECTED TO EVOLVE WITH THIS SYSTEM WITH ONE LOW
LIFTING NORTH ACROSS THE EASTERN GULF OF MEXICO, AND ANOTHER
FORMING NEAR THE EAST COAST OF FL. THE ONE ALONG THE EAST COAST OF
FL IS EXPECTED TO DEVELOP NEAR THE MELBOURNE AREA EARLY TUESDAY
AND LIFT NORTH TO COASTAL AREAS OF GA AND SC GOING THROUGH
WEDNESDAY BEFORE THEN ADVANCING INLAND. THE 00Z NAM AND 00Z GFS
ARE A LITTLE FASTER THAN THE NON-NCEP MODELS IN TAKING THE LOW
NORTHWARD. OVERALL THE 12Z UKMET WAS SEEN AS BEING THE SLOWEST,
BUT IT ALSO IS STILL PERHAPS A LITTLE TOO SLOW TO ADVANCE ITS
MID-LEVEL TROUGH NORTH AS WELL INTO THE SOUTHEAST. IN TIME, THE
00Z NAM BECOMES SOMEWHAT OF A STRONGER OUTLIER WITH THE MID-LEVEL
TROUGH AS IT LIFTS NORTH THROUGH THE SOUTHEAST AND INTO THE
SOUTHERN APPALACHIANS. THE 18Z GEFS MEAN AND 12Z ECENS MEAN BOTH
WOULD SUGGEST THE ENTIRE NON-NCEP MODEL SUITE IS A TOUCH TOO SLOW
TO ADVANCE THE MID-LEVEL TROUGH AND FL EAST COAST SURFACE LOW OFF
TO THE NORTH. SO, THE PREFERENCE WILL BE TOWARD A BLEND OF THE 00Z
GFS, 12Z ECENS MEAN AND 18Z GEFS MEAN FOR THE TIME BEING.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page