772
FXUS10 KWNH 061854
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
253 PM EDT SUN OCT 06 2019
VALID OCT 06/1200 UTC THRU OCT 10/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..UPPER TROUGH CROSSING THE GREAT LAKES THROUGH MONDAY
..ATTENDANT COLD FRONT MOVING INTO THE EAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-ECMWF BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS SHOW VERY GOOD AGREEMENT WITH THE DETAILS OF THE UPPER
TROUGH AND ASSOCIATED SHORTWAVE ENERGY THAT WILL BE CROSSING THE
UPPER MIDWEST AND GREAT LAKES REGION THROUGH MONDAY. ALTHOUGH THE
12Z ECMWF IS A BIT SLOWER THAN THE REMAINING MODEL CONSENSUS AS
THE ENERGY CROSSES THE GREAT LAKES AND THEN NORTHERN NEW ENGLAND
MONDAY THROUGH TUESDAY. AN ATTENDANT COLD FRONT WILL CROSS THE OH
VALLEY AND MOVE TOWARD THE EAST COAST BY MONDAY NIGHT AND THEN
OFFSHORE ON TUESDAY. A NON-ECMWF BLEND WILL BE PREFERRED WITH THIS
SYSTEM.
..SHORTWAVE ENERGY AMPLIFYING OVER THE MID-ATLANTIC
..DEEPENING SURFACE LOW PRESSURE OFF THE EAST COAST
..WEAK SURFACE LOW PRESSURE IMPACTING THE FL PENINSULA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: BLEND OF THE 12Z GEFS/00Z ECENS MEAN
CONFIDENCE: BELOW AVERAGE...EXCEPT ABOVE AVERAGE OVER FL
THE GUIDANCE AGAIN SUGGESTS SECONDARY SHORTWAVE ENERGY ADVANCING
ACROSS THE MID-MS AND OH VALLEYS THAT WILL BREAK AWAY FROM THE
WESTERLIES AND AMPLIFY TOWARD THE CENTRAL APPALACHIANS BY LATER
MONDAY AND TUESDAY, AND WITH AT LEAST A WEAK MID-LEVEL CLOSED LOW
EVOLVING NEAR THE NORTHERN MID-ATLANTIC REGION BY WEDNESDAY. THE
12Z NAM/GFS SOLUTIONS ARE NOW OVERALL THE STRONGER CLUSTER WITH
RESPECT TO THE HEIGHT FALL EVOLUTION, AND THE 12Z ECMWF WITH ITS
WEAKER TREND IS NOW THE WEAKEST. THE EVOLUTION OF THIS WEAKNESS
DEVELOPING OVER THE CENTRAL APPALACHIANS WILL BE CRITICAL AS THERE
ARE INDICATIONS THIS ENERGY WILL INTERACT WITH THE NORTHWEST
ADVANCE OF A SURFACE TROUGH/TROPICAL WAVE LIFTING NORTHWEST ACROSS
THE BAHAMAS AND UP OFF THE EAST COAST. IN FACT, ALL OF THE MODELS
ON THE ONE HAND SUGGEST A WEAK LOW CENTER CROSSING THE NORTHWEST
BAHAMAS AND MOVING INTO SOUTH FLORIDA BY LATE MONDAY, WITH THEN AN
AREA OF CYCLOGENESIS OCCURRING EAST OF THE CAROLINAS BY TUESDAY AS
THE UPSTREAM HEIGHT FALLS APPROACH THE EAST COAST. THERE IS A FAIR
AMOUNT OF LATITUDINAL SPREAD IN THE GUIDANCE WITH WHERE THIS
SECONDARY CYCLOGENESIS WILL OCCUR, BUT ALL OF THE MODELS HAVE
COLLECTIVELY TRENDED TOWARD A LOW CENTER TUCKING IN CLOSER TO THE
EASTERN SEABOARD BY WEDNESDAY. ONE EXCEPTION IS THE 12Z ECMWF
WHICH HAS TRENDED FARTHER OFFSHORE. THE 12Z GFS IS NOW OVERALL THE
FARTHEST WEST AND NORTH WITH THE SURFACE LOW CENTER EVOLUTION
THROUGH WEDNESDAY, AND IS ALSO WEST OF THE 12Z GEFS MEAN. THE 12Z
NAM/CMC SOLUTIONS ARE A LITTLE SOUTHEAST OF THE GFS, WITH NOW THE
12Z UKMET/ECMWF SOLUTIONS THE FARTHEST SOUTH, BUT WITH THE ECMWF
THE FARTHEST EAST. THE GFS AND ECMWF ARE NOW BOTH APPEARING TO BE
OUTLIER SOLUTIONS OVERALL RELATIVE TO THE MODEL CONSENSUS,
ALTHOUGH THE ECMWF DOES AT LEAST HAVE SOME SUPPORT FROM THE UKMET
AND 00Z ECENS MEAN. AT THIS POINT, GIVEN THE MULTI-DAY MODEL
SWINGS AND LACK OF STRONG CLUSTERING, THE PREFERENCE WILL BE TO
LEAN TOWARD A COMPROMISE OF THE ENSEMBLE MEANS WITH THE 12Z GEFS
MEAN AND 00Z ECENS MEAN. CONFIDENCE IS LIMITED WITH THE OFFSHORE
LOW CENTER EVOLUTION, BUT IS ABOVE AVERAGE WITH RESPECT TO THE
SEPARATE LOW CENTER IMPACTING THE FL PENINSULA SINCE THE GUIDANCE
SHOWS MUCH BETTER AGREEMENT THAT FEATURE.
..DEEP UPPER TROUGH/CLOSED LOW AMPLIFYING OVER THE WEST
..HIGH PLAINS CYCLOGENESIS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE MODELS ARE IN VERY GOOD AGREEMENT ON AMPLIFYING A NORTHERN
STREAM TROUGH DOWN TOWARD THE PACIFIC NORTHWEST, NORTHERN ROCKIES
AND NORTHERN HIGH PLAINS BY LATER MONDAY AND TUESDAY WHICH WILL
SEND A VERY STRONG COLD FRONT SOUTHEAST FROM CANADA ALONG WITH
MUCH COLDER AIR. AS THE COLD FRONT ADVANCES SOUTHEAST, ONE WAVE OF
LOW PRESSURE WILL DEVELOP ALONG IT OVER SOUTHEAST MT BY LATE
TUESDAY WHICH WILL CROSS THE DAKOTAS THROUGH EARLY WEDNESDAY. THE
MODELS SHOW EXCELLENT AGREEMENT WITH THIS EVOLUTION. THEN AS THE
COLD FRONT ADVANCES DOWN THE FRONT RANGE OF THE ROCKIES BY LATE
WEDNESDAY, A NEW AREA OF STRONG CYCLOGENESIS IS EXPECTED TO TAKE
PLACE OVER EASTERN CO. GIVEN THE LEVEL OF MODEL AGREEMENT WITH THE
DETAILS OF THE FRONTAL TIMING ACROSS THE GREAT BASIN AND THE HIGH
PLAINS, THE PAIR OF LOW CENTERS, AND THE DEEP TROUGH/CLOSED LOW
EVOLUTION EXPECTED OVER THE INTERMOUNTAIN WEST, A GENERAL MODEL
BLEND WILL BE PREFERRED WITH ABOVE AVERAGE CONFIDENCE.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
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