Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
1235 PM EDT Sat Jul 25 2020
Valid Jul 25/1200 UTC thru Jul 29/0000 UTC
...See NOUS42 KWNO (ADMSDM) for the status of the upper air
ingest...
12Z Model Evaluation Including Preferences and Forecast Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...Mid-upper level troughing over the northern CONUS...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend
Confidence: Above average
A mid to upper-level trough over the Northwest and adjacent areas
of southwest Canada will advance east through early next week and
gradually amplify over portions of the Midwest and Great Lakes
region going through Tuesday. In fact, all of the models show a
well-developed upper low just to the north over Ontario by the end
of the period. The model guidance is reasonably well clustered
with the timing and evolution of this energy along with the
attendant cold front crossing portions of the Plains, Midwest and
eventually the eastern U.S. So, a general model blend will again
be preferred.
...Hurricane Hanna...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Official NHC track
Best Model Proxy: 12Z NAM/GFS blend
Confidence: See latest NHC products
Hurricane Hanna will make landfall along the South Texas coast
this afternoon and across Deep South Texas tonight before crossing
into northeast Mexico early on Sunday. The 12Z NAM/GFS solutions
appear generally to be the closest to the 15Z NHC forecast track.
The 00Z UKMET becomes a bit of a faster outlier solution by this
evening and overnight and is also a bit south of the NHC track.
The 00Z CMC/ECMWF solutions are both just a little faster and a
tad north of the NHC track. For the latest information on Hanna,
please consult the latest NHC public advisory.
...Upper trough/low over California/Great Basin...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend
Confidence: Above average
A broad upper trough and embedded closed low over CA will
generally remain in place over the next couple of days, but should
then gradually advance northeast and weaken through the Great
Basin by Tuesday. Overall, the models are in good agreement
through the period with the handling of this energy, so a general
model blend will be preferred.
...New upper trough/low approaching California by Tuesday...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: Non-CMC blend
Confidence: Above average
A new upper trough and embedded closed low will be approaching CA
by late Tuesday. The 00Z CMC is a progressive outlier with this
energy. The remaining guidance is slower and agrees in still
having the bulk of the energy offshore at least through this
period, so a non-CMC blend will be preferred.
Model trends at www.wpc.ncep.noaa.gov/html/model2.shtml
500 mb forecasts at www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml
This product will terminate August 15, 2020:
www.weather.gov/media/notification/pdf2/scn20-58pmdhmd_termination.
pdf
Orrison