Scientific Forecaster Discussion

NWS Discussion
			
				

Area forecast discussion 
National Weather Service Reno Nevada 
310 am PDT Wednesday Jun 19 2013 


Synopsis... 


Breezy conditions will continue today while temperatures fall 
below seasonal averages as cooler air accompanies northwesterly 
flow. Temperatures trend back to seasonal averages by the weekend 
with dry conditions and light winds expected. 


&& 


Short term... 


Low pressure continues to push into the Pacific northwest. Showers 
and isolated thunderstorm activity will diminish over the morning 
hours as low pressure begins to track into Canada. Winds will 
pick back up during the daytime as a decent pressure gradient 
remains over northern California and western Nevada. However, this 
gradient will weaken through the day as the parent low tracks 
northeast. Winds will lighter than Tuesday, but remain a little 
breezy. Gusts will generally be around 25 miles per hour and isolated gusts 
up to 30mph north of Highway 50. The showers that occurred 
overnight ended up being farther south than previously 
anticipated, as far south as Janesville and Honey Lake. Therefore, 
have increased relative humidity for areas that received 
precipitation overnight. 


There are some differences between current and previous model 
runs for Thursday and Friday. The upper low is moving more slowly; 
this will allow for cooler air to continue to funnel into northern 
California and western Nevada. This will effectively slow the 
warming trend. Cooled the daily maximums through Friday as cooler 
air punches farther south and lingers with northwesterly flow. 
Although cooler, we will return to seasonal averages by Friday 
with highs in the low 80s for western Nevada and low to upper 60s 
in the Sierra. Boyd 


Long term...Saturday through Tuesday... 


00z model data continued to trend wetter and a bit cooler for late 
in the weekend into early next week as strong Pacific jet/precipitable water plume 
move from west of the date line into the Oregon and northern California coast 
sun-Mon. The GFS showed 120-150kt jet in the Gulf of Alaska nosing 
into northern California with precipitable water plume two inches just offshore, and upwards to 
one inch over the Sierra and western Nevada. This very moist plume will 
result in extensive cloud cover at the least with model soundings 
saturated above 600mb. Best upper forcing will be north of jet axis 
which models currently show across northeast California into northern Nevada and 
points northward. So increased cloud cover considerably sun-Monday and 
introduced a low chance of showers for the northern Sierra and areas 
north of I-80 Sun night-Monday and far north into Tuesday as upper jet 
stream begins to retreat northward in response to expanding ridge 
near The Four Corners region. Probability of precipitation will likely need to be raised 
further in these areas if models show persistence in this pattern. 
Unless models come further south with upper jet, southern areas will 
miss a chance at some early Summer rain. Cooled highs about five 
degrees through period while warming overnight lows. Winds Saturday 
will be light as weak high pressure persists for one more day over 
the Great Basin. The afternoon and evening westerlies will then kick 
in, strength highly dependent on amount of cloud cover and heating 
over the basin and range. Hohmann 


&& 


Aviation... 


Isolated to scattered showers will affect areas mainly north of a 
Susanville to Winnemucca line today. Otherwise it will be dry with a 
general west to northwest flow aloft. Gusts this afternoon will be 
in the 20-25kt range at area terminals. Hohmann 


&& 








Rev watches/warnings/advisories... 
Nevada...none. 
California...none. 
&& 


$$ 


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