Prognostic Meteorological Discussion
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000
FXUS10 KWNH 011840
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
239 PM EDT WED JUL 01 2015

VALID JUL 01/1200 UTC THRU JUL 05/0000 UTC

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

12Z NAM/GFS EVALUATION WITH FINAL PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
NAM/GFS INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE THEIR SHORT
RANGE FORECASTS.


UPPER TROUGH MOVING THROUGH WESTERN CANADA FRI/SAT
FRONT DROPPING INTO MONTANA SAT MORNING
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON 12Z CMC COMPROMISE
CONFIDENCE: ABOVE AVERAGE

THE 12Z CMC IS FLATTER THAN THE REMAINING DETERMINISTIC/ENSEMBLE
CONSENSUS BY 00Z/05 WITH THE UPPER WAVE AND IS THEREFORE SLOWER TO
BRING A COLD FRONT INTO MONTANA. THE REMAINING GUIDANCE SHOWS GOOD
AGREEMENT WITH THIS SYSTEM.


SURFACE WAVE MOVING EWD FROM KS TO THE MID-ATLANTIC THROUGH SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS / 12Z ECMWF BLEND
CONFIDENCE: SLIGHTLY BELOW AVERAGE

A LOW-MID LEVEL SHORTWAVE CURRENTLY OVER THE CNTRL PLAINS IS
EXPECTED TO REACH THE LOWER OHIO VALLEY THU NIGHT AND CNTRL
APPALACHIANS FRI NIGHT. ON FRI...THE 12Z NAM IS TOWARD THE
STRONGER/SOUTHERN SIDE OF THE GUIDANCE WITH THE LOW LEVEL WAVE
APPROACHING THE SRN-CNTRL APPALACHIANS WHILE THE 12Z GFS IS
FARTHER NORTH AND A BIT WEAKER. THE 12Z ECMWF/UKMET TRENDED IN THE
DIRECTION OF THE NAM/GFS...BUT ARE FARTHER EAST WITH THE LOW LEVEL
WAVE BY FRI MORNING ACROSS THE TENNESSEE VALLEY TO MID-ATLANTIC
REGION. THE 12Z CMC REPRESENTS AN EXTREME VERSION OF THE 12Z
ECMWF. STILL FEEL THE GFS AND ECMWF REPRESENT THE BEST COMPROMISE
HERE WITH THE BLEND SHOWN SUPPORT BY THE LATEST ENSEMBLE SCATTER
LOW PLOTS.

CONFIDENCE IS REDUCED GIVEN TRENDS DO NOT SUPPORT ONE DIRECTION OR
ANOTHER IN ANY OF THE GUIDANCE.


SHORTWAVE CLIPPING THE NRN GREAT LAKES FRI/SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/ECMWF/UKMET COMPROMISE
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

THE 12Z NAM AND CMC ARE THE SLOWEST/STRONGEST WITH THIS
FEATURE...WITH THE REMAINING AVAILABLE MODELS SHOWING AN AGREEABLE
CONSENSUS AWAY FROM THE NAM/CMC.


...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...

...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

OTTO

$$




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