area forecast discussion  fxus66 khnx 120940  afdhnx  area forecast discussion  national weather service san joaquin valley - hanford ca  240 am pdt thu jul 12 2007  .discussion...  high temperatures wednesday in the southern san joaquin valley were  2-3 degrees warmer than tuesday...while the central valley remained  near persistence due to a lingering marine air push into the northern  half of the san joaquin valley. all areas will warm today as the  upper-level ridge over arizona rebuilds into california...pushing  500-mb heights over the hanford warning/forecast area above 5880  meters. 1000-500-mb thicknesses over the region are forecast to rise  30-40 meters as the ridge moves over the region...and 850-mb  temperatures are forecast to rise 2 c...to 20-22 c. this typically  yields high temperatures for the central and southern san joaquin  valley in the lower to mid 90s...and that is in good agreement with  the forecast for today.  the main forecast concern for thew next few days is the potential  for mountain convection. short-waves rotating around the upper-level  low off the central california coast not only are drawing relatively  drier air over california but also setting up a southwest flow aloft  over the region. despite unstable conditions over the southern  sierra nevada wednesday afternoon...convection did not develop.  conditions today are forecast to be a bit more stable...so per  collaboration with neighboring wfo/s...have lowered pops for this  afternoon/evening to 10 percent over the high country near yosemite.  will keep the southern sierra nevada zones split to allow for any  updates if this assessment is wrong.  conditions are more stable friday..so have confined any token pops  to near the crest at yosemite. for saturday...the upper-level ridge  center moves into southwestern utah...turning the flow aloft over  california more southerly. have lowered pops to 10 percent over the  mountains to match neighboring offices...but have gone with 15  percent pops along the southern sierra nevada crest saturday  afternoon/evening to put thunderstorm wording in the forecast.  the upper-level trough is forecast to remain off the california  coast through monday...then move onshore monday night/tuesday  morning. temperatures will warm through monday ahead of the  trough...then cool tuesday and wednesday as the trough moves into  california. the medium-range models differ on the timing of the  trough...but the flow aloft over the central california interior is  forecast to be southwest through at least tuesday for cool and dry  conditions.  &&  .aviation...an upper trough offshore will provide a dry southwest  flow aloft providing mainly clear skies. vfr conditions will prevail  through 12z friday. for specific details...please refer to the  tafs for kmce...kfat and kbfl...and tweb routes 421 and 423.  &&  .air quality issues...  none.  &&  .hnx watches/warnings/advisories...  none.  &&   __________________________________________________________________________  sanger/mv  weather.gov/hanford Boycott Internet Spam:  See <URL:http://spam.abuse.net/spam/ The National Weather Service data is made available courtesy of the National Science Foundation-funded UNIDATA Project and the University of Michigan.

area forecast discussion  fxus66 khnx 121603  afdhnx  area forecast discussion  national weather service san joaquin valley - hanford ca  903 am pdt thu jul 12 2007  .discussion...  not really planning any changes this morning. an upper low  continues to spin around near 134w/40n. weak ripples of vorticity  were rotating around this feature and wv showed a batch of higher  upper level moisture working northeast across the central and  southern cwfa that was associated with a batch of high clouds. gfs  cross sections show the upper levels drying out by this afternoon,  and the latest water vapor confirms that drier air aloft will work  into the area so plan to keep the forecast sunny over the  valley/foothills for this afternoon. as for temps...the low level  sounding out of fresno this morning would indicate highs today in  the mid to upper 90s which the current valley zones currently  have.  concerning the threat of convection over the sierra today...plan  to keep the 10 pop we have in the grids near yosemite. just for  starters the flow aloft is southwest, which would push any convection  that tries to develop east of the crest, but there isn`t a lot of  good moisture available either. i even looked at the nam li/s and  they barely go negative this afternoon and the h7 omega values are  barely negative as well. they`ll be just enough moisture for some  cumulus to build up but the tops of any will be sheared off to the  east of the cumulus field.  &&  .aviation...an upper trough offshore will provide a dry southwest  flow aloft providing mainly clear skies. vfr conditions will prevail  through 18z friday. for specific details...please refer to the  tafs for kmce...kfat and kbfl...and tweb routes 421 and 423.  &&  .air quality issues...  none  &&  .hnx watches/warnings/advisories...  none.  &&   __________________________________________________________________________  public...stachelski  aviation/fire wx...mv/bean  weather.gov/hanford Boycott Internet Spam:  See <URL:http://spam.abuse.net/spam/ The National Weather Service data is made available courtesy of the National Science Foundation-funded UNIDATA Project and the University of Michigan.

area forecast discussion  fxus66 khnx 122123  afdhnx  area forecast discussion  national weather service san joaquin valley - hanford ca  223 pm pdt thu jul 12 2007  .discussion...  upper low near 130w continues to move northward along the western  edge of an upper level ridge axis over the western conus. drier  air aloft has cut back on cumulus development across the sierra  this afternoon so far and whatever cumulus manages to puff up  in the remainder of this afternoon will be pinned towards the  crest. have left in the grids the inherited 10 pops around  yosemite but expect it to be a quiet evening.  the upper ridge over the western conus will strengthen as we head  into the weekend. 500 mb heights/850 mb temps will rise slowly as  we move towards saturday to around 592 dm/+25 c. this will push  valley and some foothill temps back into the triple digits with  the warmest spots around 105 by saturday. the fly in the ointment  with respect to temps will be the approach of an upper level low  moving northwestward from mexico. this feature will move across  the northern baja friday night/saturday morning. models differ  with how much moisture actually gets into the area with the gfs  showing 700 mb rh values as high as 65 percent across the southern  parts of the cwfa by 18z sat while the ecmwf and nam are much  drier and have 700 mb rh values only as high as 30-40 percent in  our southern cwfa. have generally leaned towards the gfs allowing  for an increase in cumulus build up by saturday afternoon over the  sierra nevada and the tehachapis and have added in a small area of  low end pops in the tehachapis given the upslope flow. my concern  is just how much cloud cover sneaks into the valley as if we get  enough cloudiness around we will fall short on high temps  saturday. i don`t have us much above the gfs mos which seems to be  the only guidance taking any cloud cover into account over the  valley saturday. whatever convection does fire over the sierra  will ride northward towards the crest given the southerly flow.  those heading to the higher terrain for outdoor activities  saturday should be alert for the threat of convection.  the upper low that heads northwest from mexico will be off the  coast of socal on sunday. drier air aloft works in and the 700mb  flow starts to go southwesterly so have sunday played drier with  the only clouds confined to the sierra in the afternoon and  evening. left the 10 pops inherited here in continuity as  something could still fire up in the afternoon but anything looks  to be too small of a chance to put in the zones. sunday should be  the hottest/warmest day as the ridge peaks in strength this day.  by monday the approach of a deep upper level trough from the  pacific will begin to break the ridge down. still with little  change in 500 mb heights or 850 mb temps expect monday to be  nearly identical to sunday in terms of temps. the upper low off  the coast of socal sunday will cross the area monday as an  elongated piece of energy that could translate into a few high  clouds.  as we move into tuesday and wednesday the ridge will weaken  further as the deep (for this time of year) upper level trough  heads eastward from the pacific towards the pac nw. expect highs  to take a dive on tuesday due to the synoptic cooling alone. the  500 mb 588 height contour line is forecast to drop as far south by  wednesday as tijuana per the gfs and los angeles per the ecmwf.  the 12z gem shows this trough to be as deep as the gfs and ecmwf  but keeps it more offshore and still holds onto the ridging  pattern a little more. still though all models show a lowering in  heights...so expect highs to trend down overall which should bring  the valley generally below 100 degrees. if the gfs is right...we  may have some high clouds brush us in the tuesday-wednesday time  _frame_. have painted in some in the grids for now. over the sierra  looks to dry for convection...though i could see if we get just  enough moisture when the _base_ of the trough swings by if it`s at  the right time of the day a rogue shower could pop near yosemite.  &&  .aviation...an upper trough offshore will provide a dry southwest  flow aloft providing mainly clear skies. vfr conditions will prevail  through 0z saturday. for specific details...please refer to the tafs  for kmce...kfat and kbfl...and tweb routes 421 and 423.  &&  .air quality issues...  none  &&  .hnx watches/warnings/advisories...  none.  &&   __________________________________________________________________________  public...stachelski  aviation/fire wx...bean  weather.gov/hanford Boycott Internet Spam:  See <URL:http://spam.abuse.net/spam/ The National Weather Service data is made available courtesy of the National Science Foundation-funded UNIDATA Project and the University of Michigan.

area forecast discussion  fxus66 khnx 130331  afdhnx  area forecast discussion  national weather service san joaquin valley - hanford ca  831 pm pdt thu jul 12 2007  .update...am lowering temps across the entire area tonight and  friday...most noticeably across the lower elevations...as strong  onshore gradients continue to exceed model expectations. updated  forecast package coming by 900 pm pdt.  &&  .discussion...southerly flow aloft prevailing over central ca as  a result of interaction between an upper high over northern az and  an offshore upper low near 130w. typically we would expect a  warm up in this pattern. however...there is a very strong onshore  gradient with ksfo-klas currently running near 12mb as well as a  3000 ft deep marine _layer_ noted by the 00z coastal raobs and fort  ord profiler. the strong onshore gradient is re-enforcing the cooler  marine influenced airmass currently situated over the san joaquin  valley and southern sierra foothills. although the marine air is  drying out near the surface along the coast...it will remain  pooled inland for at least another day so have decided to lower  temps for the lower elevations by several deg f tonight and  friday and will be updating the entire afternoon package to  account for this.  the upper ridge is expected to strengthen over the weekend.  however... moisture undercutting the ridge may spread into our  area from the south on saturday...providing our area with some  mid/high clouds and keep temps well below guidance for another day.  the increased moisture may also set the stage for some high _base_d  convection saturday afternoon and evening. the strengthening ridge  will bring a warming trend to the area sunday and monday before  the offshore trough pushes inland over the pac nw by tuesday and  breaks down the upper ridge...resulting a some cooling over our  area toward the middle of next week as heights and thicknesses  plunge.  &&  .aviation...vfr conditions will prevail through 12z saturday. for  specific details...please refer to the tafs for kmce...kfat and  kbfl...and tweb routes 421 and 423.  &&  .air quality issues...none.  &&  .hnx watches/warnings/advisories...none.  &&   __________________________________________________________________________  public: ds  aviation/fire wx: jdb  weather.gov/hanford Boycott Internet Spam:  See <URL:http://spam.abuse.net/spam/ The National Weather Service data is made available courtesy of the National Science Foundation-funded UNIDATA Project and the University of Michigan.

area forecast discussion  fxus66 khnx 130840  afdhnx  area forecast discussion  national weather service san joaquin valley - hanford ca  140 am pdt fri jul 13 2007  .discussion...  temperatures thursday were near persistence across the central and  southern san joaquin valley thursday...except for the kern county  portion of the mojave desert where highs were up 5 degrees over  wednesday. the marine _layer_ deepened to around 4000 feet at fort  ord thursday morning...and southwest morning winds at travis afb  gusting to 25 kts brought a re-enforcing push of marine air into the  san joaquin valley. the marine _layer_ at fort ord was holding at 3000  feet early this morning...and winds at travis afb have decreased...  but the pooled marine air in the central and southern san joaquin  valley will keep temperatures below normal for a fourth consecutive  day.  the models continue to forecast another surge of monsoonal moisture  to push into southern california this weekend. the gfs indicates the  best chance for convection will be sunday...with k-indexes of 28+  over the eastern kern county deserts and the highest precipitable  water over the southern sierra nevada crest from kern county north  into madera county. given the lower spatial resolution of the  gfs...have included all of the sierra nevada high country in a  slight chance of thunderstorms...as well as the kern deserts /with  the highest pops over the eastern half/. with a southeast to south  flow aloft...could see some orographic development over the south  slope of the tehachapi mountains as well.  for now...have confined pops for slight chances of thunderstorms to  the southern sierra nevada crest saturday and monday.  the hanford warning/forecast area will see warming sunday and monday  ahead of the approaching east-pacific upper-level trough. this will  bring a brief return of triple-digit heat to much of the central and  southern san joaquin valley sunday and monday.  the trough is forecast to move onshore monday night and linger over  california tuesday through thursday. with the trough will be both  synoptic cooling and a deepened marine _layer_...so temperatures will  fall back to near normal tuesday...and a couple of degrees below  normal wednesday and thursday.  &&  .aviation...vfr conditions will prevail through 12z saturday. for  specific details...please refer to the tafs for kmce...kfat and  kbfl...and tweb routes 421 and 423.  &&  .air quality issues...  none.  &&  .hnx watches/warnings/advisories...  none.  &&   __________________________________________________________________________  sanger/jdb  weather.gov/hanford Boycott Internet Spam:  See <URL:http://spam.abuse.net/spam/ The National Weather Service data is made available courtesy of the National Science Foundation-funded UNIDATA Project and the University of Michigan.

area forecast discussion  fxus66 khnx 131618  afdhnx  area forecast discussion  national weather service san joaquin valley - hanford ca  918 am pdt fri jul 13 2007  .discussion...  twenty four hour temperature trends across the sjv showed between  1 and 2 degrees f of warming. we fell short on high temps  yesterday across the valley as marine air remain entrenched in the  valley. fort ord profiler still showed the marine _layer_ up to  around 3000 feet deep. however, the winds at travis afb were sustained  below 20 kts, the sfo-las gradient showed a weakening trend and  was down to around 7mb and the 12z oak sounding showed around +2c  of warming at 850 mb. this all translates into a warmer day across  the valley this afternoon. swing shift yesterday adjusted highs  down for this afternoon and these look reasonable...will leave  these as is.  have gutted out pops from the sierra this afternoon and evening as  yesterday was a quiet day and we remain in a dry southwest flow  aloft. at best we may get a few cumulus to develop this afternoon  near the crest...if that.  the focus this weekend will be an upper level low coming northwest  from mexico and the threat of any thunderstorms with it. other big  long range concern will be the upper trough due to move towards  the western conus by mid-week next week. we will be evaluating our  grids and the latest models as we may need to make some  adjustments for the afternoon package.  &&  .aviation...vfr conditions will prevail through 18z saturday. for  specific details...please refer to the tafs for kmce...kfat and  kbfl...and tweb routes 421 and 423.  &&  .air quality issues...  none  &&  .hnx watches/warnings/advisories...  none.  &&   __________________________________________________________________________  public...stachelski  aviation/fire wx...bean  weather.gov/hanford Boycott Internet Spam:  See <URL:http://spam.abuse.net/spam/ The National Weather Service data is made available courtesy of the National Science Foundation-funded UNIDATA Project and the University of Michigan.