987
FXUS10 KWNH 060629
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
227 AM EDT MON APR 06 2020
VALID APR 06/1200 UTC THRU APR 09/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH INITIAL PREFERENCES AND CONFIDENCE
A WELL DEFINED SPLIT FLOW PATTERN WILL CONTINUE TO DOMINATE NORTH
AMERICA OVER THE NEXT SEVERAL DAYS. THE SOUTHERN STREAM COMPONENT
TO THE SPLIT WILL CONTINUE TO BE ANCHORED BY THE ANOMALOUSLY
STRONG CLOSED LOW MOVING VERY SLOWLY SOUTHEAST DAY 1 ALONG THE
CENTRAL CALIFORNIA COAST, SWINGING MORE EAST SOUTHEASTWARD DAY 2
TOWARD THE NORTHERN BAJA PENINSULA AND THEN EAST NORTHEASTWARD
INTO THE SOUTHWEST DURING DAY 3.
THE NORTHERN STREAM FLOW WILL BE COMPRISED OF AN OMEGA BLOCK WITH
AN AMPLIFYING UPPER TROF ACROSS CENTRAL CANADA DAYS 1-2 AND MOVING
INTO THE UPPER GREAT LAKES DAY 3, AN AMPLIFYING CLOSED LOW OVER
NORTHEAST CANADA AND A CLOSED UPPER HIGH IN BETWEEN OVER FAR NORTH
CENTRAL CANADA. IN BETWEEN THE TWO CLOSED LOW COMPONENTS OF THE
OMEGA BLOCK, SHORTWAVE ENERGY PUSHING EAST FROM THE UPPER
MISSISSIPPI VALLEY INTO THE LOWER LAKES AND THE MID-ATLANTIC DAYS
1 AND 2 WILL ENHANCE LIFT OVER A NORTHWEST TO SOUTHEAST ORIENTED
WARM FRONT LYING FROM THE LOWER GREAT LAKES INTO THE UPPER OHIO
VALLEY AND MID-ATLANTIC.
WITH RESPECT TO THE ABOVE MENTIONED FEATURES IN BOTH THE NORTHERN
AND SOUTHERN STREAMS, THE NAM, GFS AND ECMWF ARE SHOWING GOOD
CONTINUITY OVER THEIR RESPECTIVE PAST THREE RUNS.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SLOW MOVING SOUTHERN STREAM CLOSED LOW.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 12Z WEDNESDAY. SLOWER
ECMWF FOR DAY 3.
CONFIDENCE: MODERATE-HIGH
THROUGH THE FIRST TWO DAYS, THERE IS LITTLE IN THE WAY OF
DIFFERENCES AT MID LEVELS. DURING DAY 3...TIMING DIFFERENCES
BEGIN WITH THE GFS ON THE MORE PROGRESSIVE SIDE INTO THE
SOUTHWEST, WHILE THE 1200 UTC SUN AND 0000 UTC EC AND EC MEAN ARE
THE SLOWEST AND THE NAM IN BETWEEN. THE OLDER (1200 UTC SUN 4/5)
OF THE CMC AND UKMET WERE CLOSER TO THE EC AND THE NEWER 0000 UTC
VERSION FOLLOW SUITE. THE GFS TENDS TO BE TOO PROGRESSIVE AND
GIVEN THE SPLIT IN THE FLOW AND THE STRONG NATURE OF THIS CLOSED
LOW, FAVOR THE SLOWER SOLUTIONS BY DAY 3.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SURFACE LOW MOVING FROM THE UPPER MISSISSIPPI VALLEY, ACROSS THE
LOWER LAKES INTO THE MID-ATLANTIC DAYS 2-3.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: MODEL BLEND WITH SPEED OF SURFACE LOW
CONFIDENCE: LOW TO MODERATE. HIGHER FOR MODERATE TO HEAVY PRECIP
THERE ARE TIMING DIFFERENCES WITH AREAS OF LOW PRESSURE MOVING
EAST ALONG THE WARM FRONTAL BOUNDARY DRAPED FROM THE LOWER LAKES
INTO THE MID-ATLANTIC. THIS PART OF THE OVERALL FLOW ACROSS THE
U.S. IS COMPRISED OF FAST MOVING SHORTWAVES. LOW CONFIDENCE IN
WHICH SPEED IS CORRECT. HOWEVER...THERE IS BETTER OVERALL
AGREEMENT FOR MODERATE TO HEAVY PRECIP IN THE VICINITY OF THIS
BOUNDARY LATE DAY 1 INTO DAY 2 FROM THE LOWER LAKES, UPPER OHIO
VALLEY INTO THE CENTRAL APPALACHIANS AND MID-ATLANTIC.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~
UPPER TROF AMPLIFYING ACROSS THE NORTH CENTRAL TIER LATE DAY 2
INTO DAY 3
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~
PREFERENCE: TOWARD THE MORE PROGRESSIVE NON-GFS SOLUTIONS.
CONFIDENCE: MODERATE
THERE ARE TIMING DIFFERENCES THAT DEVELOP LATE DAY 2 INTO DAY 3
WITH THE AMPLIFYING NORTHERN STREAM TROF ACROSS SOUTH CENTRAL
CANADA AND THE NORTH CENTRAL U.S. THE GFS IS THE SLOWEST HERE,
WHILE THE NON GFS GUIDANCE, INCLUDING THE 0000 UTC EC, CMC AND
UKMET ARE CLUSTERING FASTER. AT THE MOMENT, WE WILL FAVOR THE
MAJORITY FASTER SOLUTION WITH THIS AMPLIFYING UPPER TROF AND THE
ASSOCIATED EAST SOUTHEAST OF THE COLD FRONT FROM THE PLAINS
THROUGH THE MISSISSIPPI VALLEY AND INTO THE OHIO VALLEY AND
CENTRAL APPALACHIANS.
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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