Area Forecast Discussion
Issued by NWS San Joaquin Valley, CA

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FXUS66 KHNX 211918

Area Forecast Discussion
National Weather Service San Joaquin Valley - Hanford CA
1218 PM PDT Mon May 21 2018

.SYNOPSIS...Low pressure over the region will move east
Tuesday with a brief ridge of high pressure over the area
Wednesday and Thursday. This weekend, another Pacific low pressure
system will move into region bringing additional cooling.


.DISCUSSION...Upper low is noted spinning over the Owens Valley
late this morning and convection has already fired up over the
Sierra, with cells taking a pronounced east to west movement for
the most part. With the low remaining in the area and the
favorable northern side of the low giving the best chance of
sustained convection, today`s high pop and relatively widespread
thunderstorm threat will continue into evening.

The low is progged to only slowly migrate east to near Las Vegas
by Tuesday morning and then drift to the northeast over Nevada by
the afternoon. This position will keep the forecast area under a
favorable for Sierra thunderstorm northerly flow in the wrap
around moisture and Tuesday looks to be another active day. By
Wednesday, models eject the low well to the northeast and bring a
decent southwest flow into Central California. The dry air in the
southwest flow will end all convection except in the higher Sierra
where orographic lift will conbine with residual moisture to keep
thunder going for at least Wednesday afternoon and evening.

From Thursday and into the weekend, better agreement between
models and consistency in the GFS solution in bringing yet another
closed low into and across the region Friday and Saturday with
another threat of mainly Sierra showers and Thunderstorms. Given
all of this low pressure, temperatures will remain below normal
for the next several days.  &&

A slight chance of possible thunderstorms with local MVFR/IFR
conditions may occur over the higher elevations of the Southern
Sierra Nevada between 19Z today and 03Z Tuesday. Otherwise...VFR
conditions will prevail across the Central CA Interior during the
next 24 hours.





The level of certainty for days 1 and 2 is medium.
The level of certainty for days 3 through 7 is medium.

Certainty levels include low...medium...and high. Please visit for additional information
an/or to provide feedback.


.HNX Watches/Warnings/Advisories...


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