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Area forecast discussion 
National Weather Service Hastings NE 
1150 PM CDT Thursday Jul 3 2008 


Aviation...06z taf. VFR conditions. 


&& 


Previous discussion... /issued 321 PM CDT Thursday Jul 3 2008/ 


Short term...through 12z Saturday. Showers associated with weak mesoscale convective vortex 
sliding across Kansas have lingered across southern Kansas zones through 
much of the day...but are finally pulling east out of the County Warning Area as mesoscale convective vortex 
continues its eastward trek. Clouds are pulling east as well...with 
water vapor imagery showing subsidence across the County Warning Area keeping flat 
cumulus field in check. A look at the bigger picture shows upper ridging 
over the intermountain west...leaving the Central Plains under a 
weak northwest flow aloft. In wake of yesterday/S cold frontal 
passage...surface high pressure has ridged in from the upper Midwest 
through the Central Plains with much cooler temperatures in the 70s in 
place. 


The surface high will gradually shift eastward tonight...allowing 
weak return flow to ensue. A weak low level jet develops across the High 
Plains tonight...with decent Theta-E advection resulting across the 
western County Warning Area on eastern fringe of low level jet axis. This may bring an 
increase in middle-level clouds overnight...but not anticipating any 
precipitation to result given fairly dry low-levels and weak nature 
of low level jet. Low temperatures will be a bit below normal in the upper 50s to 
around 60. 


Looks like a nice day shaping up for the Fourth of July Holiday. The 
upper ridge axis shifts eastward...causing heights to rise across 
the Central Plains. The warming temperatures aloft combined with no real 
triggering mechanism will keep any convection capped off through 
the day. Temperatures will begin to rebound with the upper ridge axis 
nudging eastward and stronger low-level warm air advection developing as 
southerly winds increase between the surface high to the east and 
a deepening Lee trough. Have aimed highs in the middle 80s to around 
90. A stronger low level jet /around 40 kts/ develops Friday night...with 
good Theta-E advection and decent moisture convergence taking 
shape across the County Warning Area along its eastern edge. Looks sufficient to 
trigger some nocturnal convection...but thinking it will hold off 
until at least 11 PM or midnight...so shouldn/T interfere with 
area fireworks displays. Could see some isolated hailers with 
the storms Friday night given MUCAPES of 1500-2000 j/kg and 
effective bulk shear of 40 to 50 kts. Temperatures will be on the mild 
side Friday night in the middle to upper 60s. 


Long term...12z Saturday through Thursday. Forecast concerns lie with 
temperatures during the early portion of the extended period...then 
switching to precipitation chances late in the weekend/early next 
week. 


Expect precipitation to be ongoing at 12z on Saturday...lingering on 
from Friday night with the onset of warm air advection/southerly low level jet. 
Models show the 30-35kt low level jet continuing on into the morning 
hours...with it and the precipitation tapering off and leaving the 
rest of the daytime hours dry. In the upper levels...general 
overall pattern remains with ridging in the west/trough in the 
east. As has been the case over the past few days...models continue 
to show the western ridge being broken down a bit by energy moving 
in from the West Coast. This will also cause an eastward shift of 
the ridge axis...closer to our County Warning Area. At the surface...good southerly 
flow will continue through most of the weekend as high pressure 
lingers to our east and an area of low pressure develops over the 
Dakotas...with a trough draped south through the High Plains. 
Thanks to the shifting ridge and southerly flow...warmer air will 
work its way back into the Central Plains...making for a warm 
weekend. Forecast calls for highs in the 90s across the entire 
County Warning Area...and would not be surprised if southern and western areas hit 
the century mark on Saturday. During the overnight hours 
Saturday/into Sunday...these middle/upper level waves continue breaking 
down the ridge...bringing more zonal flow. Introduced small probability of precipitation 
Saturday night as warm air advection/low level jet increases once again across the 
area. Expect this to be mainly confined to the northern half of the 
County Warning Area...and be an overnight event...with the rest of Sunday remaining 
dry. Highs in the middle/upper 90s once again across the entire County Warning Area 
for Sunday. 


More widespread chance for precipitation arrives late Sunday 
night...and continues through Monday...as a bit stronger of a 
middle/upper shortwave trough crosses the plains. This system also 
pushes a frontal boundary through...which will help provide a focus 
for shower/thunderstorm development. Best chances look to be during 
the afternoon/evening hours on Monday...before tapering off 
overnight. Left Tuesday through Thursday dry...as models differ on 
the overall pattern across the Continental U.S.. the European model (ecmwf) keeps the zonal 
flow across the country with continuous disturbances passing 
through...and the GFS reamplifies the ridge over the west and keeps 
things dry. With the differences between models...did not stray 
much from HPC for temperatures...with highs remaining in the 90s. 


&& 


Gid watches/warnings/advisories... 
NE...none. 
Kansas...none. 


&& 


$$