786
FXUS10 KWNH 221712
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
111 PM EDT WED APR 22 2020
VALID APR 22/1200 UTC THRU APR 26/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH INITIAL PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...SOUTHERN STREAM TROUGH EXITING THE SOUTHERN PLAINS AND CROSSING
THE OH VALLEY THURSDAY AND MID-ATLANTIC FRIDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z UKMET/ECMWF AND 00Z ECENS WITH SOME 06Z GEFS AND
00Z CMC BLEND
CONFIDENCE: AVERAGE
THE SOUTHERN STREAM MID-LEVEL TROUGH OVER THE SOUTHERN PLAINS
TODAY REACHES THE MIDDLE MS VALLEY TONIGHT. THIS ENERGY ALONG WITH
A DEEPENING SURFACE LOW CENTER WILL THEN ADVANCE NORTHEAST AND
CROSS THE OH VALLEY THURSDAY AND PUSH OFF THE NORTHERN
MID-ATLANTIC COAST FRIDAY AS AN ATTENDANT COLD FRONT SWEEPS ACROSS
THE SOUTH. THE 12Z GFS HAS DRAMATICALLY SLOWED THIS SYSTEM FROM
BEING ONE OF THE FASTEST TO THE SLOWEST AND REMAINS FARTHER NORTH
WITH ITS SURFACE LOW TRACK OVER THE OH VALLEY/MID-ATLANTIC AND IS
THUS NOT PREFERRED. THE 12Z NAM REMAINS THE FASTEST SOLUTION WITH
THE TROUGH AND SURFACE LOW AND IS THUS ALSO NOT PREFERRED. THE 00Z
CMC IS THE WEAKEST WITH ITS SURFACE LOW, BUT IS IN LINE WITH THE
00Z ECMWF AND UKMET FOR LOW TRACK. REGARDING TIMING AND DEPTH OF
THE SYSTEM, THE 00Z UKMET AND 00Z ECMWF HAVE BETTER ENSEMBLE
SUPPORT (06Z GEFS/12Z ECENS MEANS). SO, WILL FAVOR A BLEND OF THE
UKMET/ECMWF SOLUTIONS AND ALONG WITH A PREFERENCE FOR THE 00Z
ECENS ENSEMBLE MEAN ALONG WITH SOME INCLUSION OF THE 06Z GEFS AND
00Z CMC FOR THE TIME BEING.
...NORTHERN STREAM SHORTWAVE/LOW CENTER ACROSS THE NORTHERN PLAINS
TONIGHT/THURSDAY AND MIDWEST FRIDAY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z ECMWF/CMC
CONFIDENCE: AVERAGE
GUIDANCE BRINGS A NORTHERN STREAM SHORTWAVE AND ASSOCIATED LOW
CENTER DOWN FROM CANADA AND ACROSS THE EASTERN DAKOTAS TONIGHT
INTO THURSDAY AND THEN ATTEMPT TO AMPLIFY IT A BIT OVER THE
MIDWEST ON FRIDAY. THE 00Z UKMET IS THE STRONGEST SOLUTIONS WITH
THIS ENERGY. WHILE MOST OF THE MODELS GENERALLY DISSIPATE THE LOW
CENTER, THE UKMET ACTUALLY HOLDS ON TO A RATHER WELL-DEFINED LOW
CENTER OVER THE MIDWEST GOING INTO SATURDAY. THE 12Z NAM/GFS AND
00Z CMC/ECMWF ARE ALL WEAKER AND GENERALLY FAVOR THE SOUTHERN
STREAM LOW OVER THE TN VALLEY BY FRIDAY NIGHT WITH THE NAM OVERALL
THE WEAKEST. A MAINTENANCE OF THE 00Z ECMWF/CMC PREFERENCE REMAINS
FOR NOW.
..SHORTWAVE TROUGH DIGGING ACROSS THE INTERMOUNTAIN WEST
..ENERGY AMPLIFYING INTO THE LOWER MS VALLEY BY SATURDAY
..ASSOCIATED DEEPENING SURFACE LOW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 00Z CMC/ECMWF AND ECENS MEAN
CONFIDENCE: SLIGHTLY BELOW AVERAGE
A SHORTWAVE TROUGH CURRENTLY SHIFTING EAST TO THE PACIFIC
NORTHWEST COAST IS FORECAST TO TAKE A SOUTHEAST TURN AS IT CROSSES
THE NORTHERN ROCKIES THURSDAY NIGHT AND AMPLIFY ACROSS THE
SOUTHERN PLAINS ON FRIDAY BEFORE CROSSING THE LOWER MS VALLEY BY
FRIDAY NIGHT AND PUSHING INTO THE MIDWEST SATURDAY. GUIDANCE IS IN
AGREEMENT ON THE TROUGH BECOMING NEGATIVELY TILTED FRIDAY NIGHT,
DRIVING ANOTHER DEEPENING SURFACE LOW CENTER. THE 12Z NAM AND 00Z
UKMET BECOME WEAKER OUTLIERS BOTH AT THE SURFACE AND ALOFT WITH
THE SYSTEM, WITH THE MAIN DIFFERENCE BEING THAT THE UKMET IS
SUGGESTING TWO LOW CENTERS WITH OVER THE LOWER MS VALLEY AND ONE
EVOLVING OVER THE MIDWEST (MENTIONED IN THE PREVIOUS SECTION) BY
FRIDAY NIGHT GIVEN PROXIMITY OF STRONGER NORTHERN STREAM SHORTWAVE
ENERGY LURKING OVER THE MIDWEST. THE 12Z GFS REMAINS TOO
PROGRESSIVE BY FRIDAY/SATURDAY AND PROBABLY TAKES ITS ENERGY A BIT
TOO FAR NORTH, BUT IT HAS AGREEMENT WITH THE UKMET IN HAVING
STRONGER NORTHERN STREAM ENERGY NEARBY. THE DIFFERENCE BETWEEN THE
UKMET AND GFS REMAINS THAT THE GFS STILL HAS A MORE DOMINANT
SOUTHERN STREAM SHORTWAVE TROUGH AND THUS A DOMINANT SOUTHERN
STREAM SURFACE LOW.
THE 12Z GFS IS STILL SUPPORTED BY THE 00Z CMC AND 00Z ECMWF
SOLUTIONS WITH THE IDEA OF THERE BEING ONE CONSOLIDATED LOW
EVOLVING THROUGH THE LOWER MS VALLEY BY THE END OF THE PERIOD AND
A MORE DOMINANT SOUTHERN STREAM TROUGH, BUT THAT IS WHERE THE
AGREEMENT ENDS AS THE CMC/ECMWF CAMP IS FARTHER SOUTH AND SLOWER
WITH THE SURFACE LOW EVOLUTION. THE CMC/ECMWF CAMP IS SUPPORTED BY
THE 00Z ECENS MEAN AND SOMEWHAT BY THE 06Z GEFS. THE PREFERENCE
WILL REMAIN A BLEND OF THE SLOWER CMC/ECMWF AND ECENS MEAN.
HOWEVER, GIVEN SOME OF THE UNCERTAINTIES OVER HOW STRONG THE
NEARBY NORTHERN STREAM ENERGY AND RELATED INTERACTION WILL BE,
CONFIDENCE IS A BIT LIMITED IN THE FRIDAY/SATURDAY TIME FRAME.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
JACKSON
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