951
FXUS10 KWNH 301832
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
232 PM EDT TUE JUN 30 2020
VALID JUN 30/1200 UTC THRU JUL 04/0000 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
19Z UPDATE: NO SIGNIFICANT CHANGES MADE TO THE BLEND PREFERENCES
WITH THE REST OF THE 12Z GUIDANCE NOW AVAILABLE.
CLOSED LOW ANCHORED OVER NEW ENGLAND...TRANSITIONING OFF
MID-ATLANTIC BY FRIDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND DAY 1/2; NON-UKMET BLEND DAY 3
CONFIDENCE: ABOVE AVERAGE
MODEL GUIDANCE IS IN EXCELLENT AGREEMENT THROUGH DAY 2 WITH THE
EVOLUTION OF THE CLOSED LOW THAT HAS BEEN ANCHORED OVER NEW
ENGLAND. BY 48-60 HOURS, TROUGHING FROM THE NORTH DIPS DOWN WHICH
WEAKENS THE CLOSED LOW AND GRADUALLY PUSHES IT EASTWARD OFF THE
COAST. A PORTION OF THAT DROPS SOUTHEASTWARD WITH A BROAD BUT WEAK
TROUGH BY DAY 3. HERE, THE UKMET IS SLOWER AND DISPLACED WESTWARD
OF THE MODEL CONSENSUS. THEREFORE, A GENERAL MODEL BLEND IS
PREFERRED FOR DAYS 1/2 AND A NON-UKMET BLEND FOR DAY 3.
DEEP UPPER TROUGH/CLOSED LOW ACROSS THE INTERMOUNTAIN WEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-CMC BLEND
CONFIDENCE: AVERAGE
UPPER LEVEL LOW OVER THE INTERMOUNTAIN WEST IS EXPECTED TO LIFT
NORTHEAST/NORTH TOWARD THE NORTHERN ROCKIES WHILE ANOTHER
SHORTWAVE TROUGH DROPS SOUTHWARD OVER THE PACIFIC NW. THE PHASING
OF THIS ENERGY WILL KEEP THE CLOSE LOW IN PLACE THROUGH MUCH OF
THE PERIOD WITH SOME TENDENCY TO LIFT FURTHER NORTH INTO THE
CANADIAN ROCKIES LATE IN THE DAY 2 PERIOD AND INTO DAY 3. ANOTHER
COMPACT SHORTWAVE TROUGH THEN SWINGS ONSHORE THE PACIFIC NW COAST
TO FINISH THE FORECAST PERIOD. IN THE LARGE SCALE SENSE, THERE IS
RELATIVELY GOOD MODEL AGREEMENT BUT WITH INDIVIDUAL LOBES OF
VORTICITY ROTATING THROUGH THE FLOW, SOME TIMING AND STRENGTH
DIFFERENCES CREEP UP. THE CMC REMAINS A BIT OF AN OUTLIER,
ESPECIALLY BY DAY 3, AS IT'S TOO FAST AND TOO DEEP WITH THE
SHORTWAVE MOVING ONSHORE WASHINGTON STATE. OTHERWISE, GUIDANCE IS
IN GOOD SHAPE TO GO WITH A BLEND OF THE OTHER DETERMINISTIC
GUIDANCE.
MCV CROSSING THE MIDDLE AND UPPER MS VALLEY THROUGH WEDNESDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: AVERAGE
A CONVECTIVELY ENHANCED MCV ONGOING ACROSS THE MID-MS RIVER
VALLEY, STUCK BETWEEN THE DOMINANT CLOSED LOW FLOWS ON EITHER
SIDE, WILL GRADUALLY DRIFT EASTWARD/SOUTHEASTWARD OVER THE NEXT
COUPLE OF DAYS. BY DAY 2, WITH BUILDING HEIGHTS THROUGH THE
CENTRAL US, THE BULK OF THIS ENERGY IS PUSHED EASTWARD AND
GRADUALLY DROPS TOWARD THE GULF STATES REGION (SEE SECTION BELOW).
MODEL GUIDANCE HAS IMPROVED SUCH THAT A GENERAL MODEL BLEND CAN BE
USED FOR THIS AREA NOW.
MID-LEVEL CLOSED LOW OVER THE GULF COAST BY FRIDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND-
CONFIDENCE: ABOVE AVERAGE
MID-LEVEL TROUGHING AND A DEVELOPING CLOSED LOW OVER THE GULF
COAST STATES IS EXPECTED BY THE END OF THE WEEK, WITH WEAK
SHORTWAVE ENERGY DROPPING FROM THE MID-SOUTH. THERE IS DECENT
AGREEMENT WITH THE AVAILABLE DETERMINISTIC GUIDANCE, THE ONLY
EXCEPTION BEING THE 12Z NAM IS SPATIALLY DISPLACED FURTHER NORTH
FROM THE OTHER GUIDANCE, BUT IT ISN'T MUCH. SENSIBLE WEATHER
DIFFERENCES ARE LIKELY TO BE DRIVEN FROM MORE MESOSCALE PROCESSES,
SO A GENERAL MODEL BLEND IS PREFERRED FROM A MASS FIELD
PERSPECTIVE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
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