Prognostic Meteorological Discussion
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000
FXUS10 KWNH 241837
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
237 PM EDT SAT JUN 24 2017

VALID JUN 24/1200 UTC THRU JUN 28/0000 UTC

...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...

12Z MODEL EVALUATION...INCLUDING PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


...LONGWAVE TROUGH DIGGING ACROSS THE CENTRAL/EASTERN U.S....
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

PREFERENCE: BLEND OF THE 12Z GFS AND 12Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

MULTIPLE SHORTWAVE IMPULSES MOVING ACROSS THE MIDWEST AND DOWN
ACROSS THE GREAT LAKES AND NORTHEAST WILL ALLOW A LONGER WAVE
TROUGH TO EVOLVE OVER THE CENTRAL/EASTERN U.S. THIS WEEKEND AND
THEN GRADUALLY FOCUSING MORE TOWARD THE EAST COAST BY MON/TUES AS
THE LAST IN A SERIES OF SHORTWAVE TROUGHS PIVOTS DOWN ACROSS THE
LOWER GREAT LAKES/OH VALLEY REGION. THE MODELS ARE IN VERY GOOD
MASS FIELD AGREEMENT THROUGH SUN...BUT BY MON AND TUES THE 12Z NAM
AND 12Z GFS BECOME A BIT FASTER THAN THE 12Z UKMET/12Z CMC AND 12Z
ECMWF TO ADVANCE THE LONGWAVE TROUGH TOWARD THE EAST COAST. THE
NAM AND CMC ARE ALSO SEEN AS BEING A LITTLE SHARPER THAN THE
REMAINING GUIDANCE WITH SHORTWAVE ENERGY DIGGING DOWN ACROSS THE
OH VALLEY/CENTRAL APPALACHIANS AND MID-ATLANTIC ON TUES. WILL
COMPROMISE BETWEEN THE GFS AND ECMWF AT THIS POINT.


...UPPER LOW MOVING INTO BRITISH COLUMBIA BY MON...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

PREFERENCE: BLEND OF THE 12Z GFS/12Z UKMET AND 12Z ECMWF
CONFIDENCE: ABOVE AVERAGE

ALL OF THE MODELS INDICATE AN UPPER LOW EXITING THE GULF OF AK AND
MOVING INTO BRITISH COLUMBIA BY MON WITH A SOUTHWARD EXTENSION OF
A TROUGH AXIS IMPACTING THE PACIFIC NORTHWEST. BY TUES...THIS
ENERGY WILL MOVE EAST ACROSS ALBERTA AND OVER THE NORTHERN HIGH
PLAINS. THE 12Z NAM IS A STRONGER OUTLIER SOLUTION WITH THIS
SYSTEM...WITH THE 12Z CMC ACTUALLY NOW THE WEAKEST SOLUTION. THE
12Z GFS/12Z UKMET AND 12Z ECMWF ARE PRETTY WELL CLUSTERED WITH
TIMING/DEPTH AT THIS POINT...SO A GFS/UKMET/ECMWF BLEND WILL BE
PREFERRED.


...DAMPENING UPPER LOW APPROACHING NORTHERN CA/OR BY MON...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

PREFERENCE: GENERAL MODEL COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE GUIDANCE BRINGS AN UPPER LOW NORTH OUT OF THE SUBTROPICS THIS
WEEKEND OFFSHORE THE WEST COAST AND THEN ADVANCES IT NORTHEAST IN
A RAPIDLY WEAKENING FASHION TOWARD NORTHERN CA/OR BY MON. THE
SYSTEM SHOULD ARRIVE AS AN OPEN WAVE AND SHEAR INLAND THROUGH TUES
ACROSS THE GREAT BASIN. THE MODELS ARE IN VERY GOOD AGREEMENT AT
THIS POINT...SO A GENERAL  MODEL COMPROMISE WILL BE PREFERRED.


WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML... /ALL LOWER CASE/
WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML... /ALL LOWER CASE/

ORRISON

$$





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