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1996-04-19


SUCCESS 48 hour Meteorological Forecast


12z 19 April 1996

Forecast based on

  • on satellite
  • current surface observations
  • 00 UTC ETA
  • 00 UTC NGM

Synopsis


A strong zonal jet extending eastward from the Pacific coast into the
Mississippi valley continues to be the dominant feature influencing the weather
over the central plains. A series of fast moving and rather vigorous shortwave
impulses are moving through the flow with the eastern-most of these causing
cyclogenesis over Nebraska and Kansas this morning. Upstream, a shortwave
impulse is approaching the northern California coast. Satellite imagery
shows that the zonal flow is rather dry with primarily mid and low level
cloudiness in the vicinity of the strongest dynamical forcing. A vigorous
westerly wind is setting up over the central plains as the surface low deepens
in Nebraska and Kansas.

Prog Discussion



Cyclogenesis will continue over the Plains as the low in Nebraska and
Kansas moves eastward today. Central Kansas and Northern Oklahoma will
experience strong southwesterly winds in an extremely tight pressure gradient
in the lower levels. The shortwave entering western North America will
cause height falls throughout the southwestern United States and spawn
surface low pressure near the four corners region during the next 24 hours.
Numerical guidance suggests that the upper tropospere will remain dry
during the period. Areas of cirrus cloudiness are expected to generate
in response to the deepening system in the Southwest, although the extent
of this development is uncertain at this time. The mid and lower troposphere
will remian dry through the period.

48 hour Forecast:

12z 19 Apr - 00Z 20 Apr: The sky will remain clear and the westerly winds strong
throughout the day. Wind speeds will be sustained near 20-25 knots with
gusts to 30 knots. High temperatures in the 70's.

00Z 20 Apr - 12Z 20 Apr: Continued clear with diminishing winds. Temperatures
are expected fall into the 50's.

12z 20 Apr - 12Z 21 Apr: High clouds are expected in the region during this
period as the low in the southwest deepens. Winds will become southerly
during the day with speeds less than 20 knots. Temperatures in the low
80's.

Extended Range Discussion:


12z 21 Apr - 12Z 22 Apr: The low in the Southwest will likely generate
mid level cloudiness and a chance of precipitation over the region Sunday
and Monday as it moves into the southern Plains.

Mace and Walker

1996-04-18


SUCCESS 48 hour Meteorological Forecast


12z 18 April 1996

Forecast based on

  • on satellite
  • current surface observations
  • 00 UTC ETA
  • 00 UTC NGM
  • 09 UTC MAPS/RUC
  • MRF
  • 12z ECWMF

Synopsis


The nose of the jet is entering the TX/OK panhandle. Over KS and OK the upper
level winds are 70 kts and should increase to 100 kts by 00 Fri 19. A shortwave
is centered over KS/OK and will track to the northeast as the day progresses.
The winds have shifted from southerly to northerly in lieu of the early morning
frontal passage.

Prog Discussion



All the models agree reasonably well with the placement and strength of the upper
level jet. At mid-levels, the ETA and AVN form a shortwave ridge over KS/OK after
the shortwave moves to the northeast. The NGM does not resolve this shortwave
ridge whose axis is centered over WY/NE border. At the surface, a low will form
in western KS in response to a strong upstream shortwave.

48 hour Forecast:

12z 18 - 00Z 19 Apr: A shortwave is over KS/OK and the jet nose is entering the
TX/OK panhandle. The shortwave will move to the northeast and a shortwave ridge
will form over WY/NE. The day should be sunny and warm. Highs upper 70s. The
wind will be northwesterly in the morning changing to westerly by the afternoon,
20 kt or greater with gusts to 30 kts.

00Z 19 Apr - 12Z 19 Apr: A low will form in western KS. The upper level jet will
be directly over KS/OK with a jet max of 110. Clear skies with temperatures in
the upper 40s can be expected. The winds will decrease and shift becoming more
southerly.

12z 19 Apr - 12Z 20 Apr: The surface low will move to N. MO/IL. Highs in the upper
70's and mostly sunny. Some low level moisture is associated with the next shortwave
from the west. Mid-level clouds may be contained to the far north/northwest of KS.
Westerly winds at 10-15kts.

Extended Range Discussion:


12z 21 Apr - 12Z 22 Apr: Dry and cooler most areas. Highs upper 60s,low 70s.
The ECMWF has the zonal upper level wind pattern changing by 12Z Sat. 20 with
a ridge building in the west.

Walker and Mace

1996-04-17


SUCCESS 48 hour Meteorological Forecast


12z 17 April 1996

Forecast based on

  • on satellite
  • current surface observations
  • 00 UTC ETA
  • 00 UTC NGM
  • 09 UTC MAPS/RUC
  • MRF
  • 12z ECWMF

Synopsis


The upper level ridge axis is centered over the Dakotas and eastern Nebraska.
By tonight, it should be centered over Ontario, Wisconsin, and Illinois.
The upper level flow is zonal from the east Pacific to the Rockies. A 100 kt
jet max is on the central coast of California. The jet is forecast to increase
by 30 kts by the end of the day. A weak surface trough extends from Nebraska
to the panhandle of Texas. No weather and few low level and mid-level clouds
are associated with this system. A shortwave exiting the Rockies is present
on the IR satellite. Thin cirrus are present over Salina. The winds have been
15-20kts since yesterday afternoon and will increase to 30 kts by this afternoon.

Prog Discussion



The NGM and ETA agree reasonably well with the placement of 500 mb ridge and
shortwaves. They do differ in the placement of the northern Plains surface low
and its intensity. The 300 mb jet has a little more eastward and northward
extent in the NGM run as compared to the ETA run.

48 hour Forecast:

12z 17 - 00Z 18 Apr: A shortwave is exiting the Rockies and will travel eastward
into the Plains. At 300 mb, difluent flow exists over northern KN, NE, and IA.
These two features should produce patchy cirrus over these state. Today should
reach 85 with the winds out of the south changing to the southwest at 30 kts.

00Z 18 Apr - 12Z 18 Apr: Another shortwave is entering the Rockies. The surface
trough will be east of Salina. The winds will become more westerly and decrease
by 10 kts. The night will have temperatures in the lower 50s and low level clouds.

12z 18 Apr - 12Z 19 Apr: The previously mentioned upstream shortwave will be ready
to exit the Rockies at 00Z Fri. A 300 mb jet nose will be over OK. Cirrus are
expected to form over the CART site in lieu of the jet nose. By 00Z Fri, the jet
be will over OK with a 140 kt jet max
entering the TX/OK panhandle. A complex surface pattern will form over KN in response
to the SW exiting the Rockies. The temperature will drop 5-10 degrees and the winds
will be out of the west at 10-15 kts.

Extended Range Discussion:


12z 19 Apr - 12Z 20 Apr: EMRF run was old. The zonal trend previously advertised
could change by Sat. 20 as both the ETA and NGM or digging a trough at 140W and
building a ridge at 120W at 500mb. A cold front should pass Fri. bringing cooler
temperatures Sat. (60's). The winds will be strong on Sat. behind the front.

Walker and Mace

1996-04-16


SUCCESS 48 hour Meteorological Forecast


12z 16 April 1996

Forecast based on

  • on satellite
  • current surface observations
  • 00 UTC ETA
  • 00 UTC NGM
  • 09 UTC MAPS/RUC
  • MRF
  • 12z ECWMF

Synopsis


Thin cirrus and persistent contrails are already presentnt over
Salina. The upper level ridge axis at 500 and 300 mb is just west of Kansas
and Oklahoma. The surface high which built in the midwest yesterday will
move to the southeast as a strong surface low moves from the Pacific north-
west into the northern Plains and Alberta/Saskatchewan. The surface pressure
gradient will gradually increase throughout the day resulting in southerly
to southwesterly winds of 15-20 kts by the late afternoon. The day should
be sunny with thickening cirrus as the day progresses. The IR satellite
imagery shows cirrus spilling over the ridge axis into Kansas and Oklahoma.

Prog Discussion



The NGM, ETA, and AVN handle the speed of the Pacific
northwest shortwave and placement of the northern Plains surface low differ-
ently. We have gone with the slower ETA solution which keeps the surface
trough west of the forecast area and schedules the frontal passages to
occur after 00z Thu 18. All models show the upper level pattern to become
zonal by 00z Thu 18. The MRF shows the zonal pattern to persist, and it
does not change until 00z Mon 22.

48 hour Forecast:

12z 16 - 00Z 17 Apr: An upper level ridge is centered over the eastern
Rockies. The ridge will flatten as a strong Pacific northwest shortwave moves
through it. The winds will gradually increase throughout the day as the
surface gradient increases in the northern and central Plains in response
to a surface low progressing out of the Pacific northwest into Alberta/Sas-
ketchewan. The day should be clear with increasing cirrus clouds. The temp-
erature will rise into the upper 70's.

00Z 17 Apr - 12Z 17 Apr: A Pacific shortwave moves on shore. The 500 mb ridge
axis is now centered over MN, IO, and MO. At the surface, a front is analyzed
over TX/OK pandhandle and western Kansas. The warm southerly flow will keep
the temperatures in the 50's.

12z 17 Apr - 12Z 18 Apr: The upper level flow will become zonal and a 120 kt
jet is analyzed on the west coast at 35N. A cold frontal passage is progged
for late Wed. night/early Thur. morning (LST). Ahead of the front, there is a
slight chance of scattered thunderstorms if moisture advects from the south.
The winds will remain strong (20-25 kts, gusts to 30 kts) and southernly. The
temperatures will be in the upper 70's and lower 80's. High level clouds will
persist.

Extended Range Discussion:


12z 18 Apr - 12Z 19 Apr: After the cold frontal passage, the daytime tempera-
tures will drop by 10-15oF, and the winds will become northernly. The upper
level flow pattern will be zonal at 500 and 300 mb, with the polar jet centered
over southern CA and AZ.

Walker and Mace

1996-04-15


SUCCESS 48 hour Meteorological Forecast


12z 15 April 1996

Forecast based on

  • on satellite
  • current surface observations
  • 00 UTC ETA
  • 00 UTC NGM
  • 09 UTC MAPS/RUC
  • MRF
  • 12z ECWMF

Synopsis


Deep low pressure is exiting the area this morning. The low
developed as a series of fastmoving shortwaves passed around the base of
a trough that moved slowly eastward over the Plains yesterday. A cool
northerly flow of air prevails over the plains while high pressure builds
from the west. The high amplitude ridge over the Rocky Mountains is
moving slowly eastward as several significant impulses aproach the west
coast of North America.

Prog Discussion



High pressure will build over the area today causing
the northerly winds to diminish and allow temperatures to moderate. As
the pacific impulses move onshore this afternoon, the Rocky Mountain ridge
will erode and move eastward. With the weakening ridge over the plains
and deepening low pressure in the West, high clouds are expected over the
region tomorrow. A trough in the lee of the Rockies will deepen tomorrow
afternoon resulting in a moderate southerly wind.

48 hour Forecast:

12z 15 Apr - 00Z 16 Apr: Mostly clear today with moderating temperatures
and diminishing northerly winds. Expect winds to decrease from 15 knots
this morning to 8-10 knots by evening and a high temperature in the
mid 50's.

00Z 16 Apr - 12Z 16 Apr: Continued clear with some fog possible by early
morning. Winds will be light and variable becoming light southerly by
sunrise. Temperatures will fall into the upper 30's.

12z 16 Apr - 12Z 17 Apr: The day should begin cloudless with a light
southerly surface wind that will increase in intensity during the day.
Thin cirrus are likely by noon. These clouds are expected to thicken during
the afternoon. Winds will increase from southerly at 10 knots during the
morning to southwesterly 15-20 knots gusting to 25 knots during the afternoon.
Temperatures will rise into the the 70's.

Extended Range Discussion:


12z 17 Apr - 12Z 18 Apr: Strong low pressure will develop in the northern
Rockies and approach the plains. Winds aloft will be southwesterly
and strong and should supply ample moisture for clouds in the middle and
upper troposphere. Surface pressure gradients will increase and winds will
be southerly 20 knots gusting to 30-35 knots by afternoon. Thunderstorms
are a distinct possibility during this period.

Mace and Walker

1996-04-14

SUCCESS 48 hour Meteorological Forecast

 

12z 14 April 1996

Forecast based on

  • on satellite
  • current surface observations
  • 00 UTC ETA
  • 00 UTC NGM
  • 09 UTC MAPS/RUC
  • MRF
  • 12z ECWMF

 

Synopsis

A strong shortwave trough over northeastern Kansas is rotating around the base the longwave system situated over the central plains. An associated surface system is moving into western Missouri. An occluded frontal band with rain and embeeded convection arcs from northwestern Louisana throug Illinois, the Dakotas and northwestern Kansas.

 

Prognosis Discussion

The system in the Plains is expected to lift northeastward while a cold northwesterly flow establishes over Kansas and Oklahoma. Strong high pressure will build into the region as the upper level ridge advances over the Rockies. This ridge will deamplify with time and a much weakened ridge axis is progged over the central plains on tuesday.

 

48 hour Forecast:

12z 14 Apr - 00Z 15 Apr: Cloudy and cold with isolated rain/snow showers. Winds in Salina will be from the northeast becoming northerly 15-20 knots. Near the central facility, winds will become northerly by 20z.

00Z 15 Apr - 12Z 15 Apr: Continued cloudy, cold and windy with snowshowers decreasing.

12z 15 Apr - 12Z 16 Apr: Mostly cloudy boundary layer clouds will decrease during the day. Winds will be northerly 15-20 knots decreasing somewhat during the afternoon and evening. Maximum temperatures will struggle into the low 50's.

 

Extended Range Discussion:

12z 16 Apr - 12Z 17 Apr: There is a reasonable expectation that cirrus will spread over the region from the west during the mid morning and persist into the evening. Winds will be light initially and become southerly during the afternoon and likely increase in speed.

Mace and Walker

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