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Latest ZFP from WFO RIW
	
National Weather Service Local Forecast for Star Valley Ranch
Updated: 25 Apr 01:55 am MDT

Overnight... Clear, with a low around 29. East southeast wind
around 6 mph. 

Wednesday... Sunny, with a high near 61. Light and variable
wind becoming west southwest 5 to 8 mph in the afternoon. 

Wednesday Night... Mostly clear, with a low around 33. West
wind 5 to 8 mph becoming light and variable. 

Thursday... Sunny, with a high near 64. East northeast wind
around 6 mph becoming calm  in the afternoon. 

Thursday Night... Clear, with a low around 33. Light and
variable wind becoming east southeast around 5 mph after midnight. 

Friday... Sunny, with a high near 71. East southeast wind
around 6 mph becoming southwest in the afternoon. 

Friday Night... Partly cloudy, with a low around 38. Southwest
wind around 5 mph becoming southeast in the evening. 

Saturday... A 20 percent chance of showers after noon.  Partly
sunny, with a high near 67.

Saturday Night... A chance of showers and thunderstorms. 
Mostly cloudy, with a low around 36. Chance of precipitation is 30%.

Sunday... A chance of showers, with thunderstorms also possible
after noon.  Partly sunny, with a high near 55. Chance of
precipitation is 30%.

Sunday Night... A slight chance of rain and snow showers. 
Mostly cloudy, with a low around 33.

Monday... A chance of rain and snow showers. Some thunder is
also possible.  Mostly cloudy, with a high near 51.

Monday Night... A chance of rain and snow showers.  Mostly
cloudy, with a low around 31.

Tuesday... A slight chance of rain and snow showers. Some
thunder is also possible.  Mostly cloudy, with a high near 51.

	

Latest AFD from WFO RIW
	National Weather Service Riverton WY
156 AM MDT Wed Apr 25 2018

.SHORT TERM...Today through Friday night

A shortwave ridge will move across the region today, in the wake of
Tuesday's disturbance, bringing dry conditions and clear skies to
the forecast area. Southwest winds will increase across the Wind
Corridor after sunrise this morning, in advance of a a quick and
relatively strong cold front. Red Flag conditions will be in effect
for portions of southern Natrona and much of Natrona counties by
this afternoon, as RH values drop into the lower to middle teens.
The cold front will enter northern portions late Wednesday
afternoon/evening and sweep through east of the Divide through the
overnight hours. Isolated to scattered rain and snow showers will be
possible across the Bighorn Basin and Johnson and Natrona counties
Wednesday night, with snow staying in the higher elevations. After a
chilly start Thursday morning (especially for portions of Johnson
County), a massive ridge will build over much of the Intermountain
West. This ridge will slowly progress eastward Thursday and Friday,
as a cut off low moves onshore by Friday. Moisture from this system
could begin to impact western portions Friday night.

.LONG TERM...Saturday through Wednesday

Overview...A Pacific cold front will push across the area on
Sunday. Breezy, warm and dry conditions will elevate fire weather
conditions across central Wyoming, high temperatures expected in
the 70s to near 80. Showers and a few thunderstorms will begin to
push into the west through the afternoon and evening. Breezy to
windy conditions with slightly cooler temperatures will accompany
the front on Sunday with chances of valley rain and mountain snow
showers continuing across the west. A cooler and unsettled pattern
takes shape over the western U.S. Monday through Wednesday A
cooling trend follows Monday through Wednesday with isolated to
scattered showers along with slight chances of afternoon/evening
thunderstorms. Issued AT 1217 AM MDT Wed Apr 25 2018

Discussion...Cutoff upper low off the west coast is expected to get
kicked onshore Saturday morning and shear/fragment into strong
downstream ridge over the Rockies and High Plains.  ECMWF and
Canadian are slower and further west than GFS lifting upper low NNE
across eastern Idaho on Sunday, and the slower guidance is
preferred.  For forecast purposes, chances of precipitation are
confined mostly to the west with slower scenario on Saturday with
cold frontal passage not expected until Sunday.   ECMWF shows
surface low just north of Sheridan Sunday afternoon, wrapping higher
SCAPE >= 1000j/kg into NE Wyoming. Forecast confidence is too low
for mention of possible strong/severe potential with this setup on
day 5, but will monitor at this stage for trends and consistency.
Both GFS and ECMWF show a split flow setting up by midweek with
ridge just off the west coast, and upper low digging south across
California into the SW U.S.  ECMWF has the low near Las Vegas by 00z
Tuesday, GFS races it into the Four Corners region.  The slower
solution will most likely win out again, especially with no kickers
within range upstream.  Most precipitation with this system should
remain to our south with this system through Wednesday.


&&

.AVIATION...For the 12Z TAFS through 12Z Thursday

East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Routes

VFR with increasing high cloudiness through 00Z Thursday. A lee
trough developing will result in windy southwest to west wind
developing from South Pass to Casper, and lee side of mountain
ranges. A cold front is expected to push into northern Wyoming
between 21Z Wednesday and 00Z Thursday. This cold front will sweep
to the Continental Divide by 03Z Thursday with breezy to windy
northerly winds developing in wake of the cold front. MVFR ceilings
are expected to develop in some areas a few hours after frontal
passage, with a window of 3 to 6 hours where some valley
rain/mountain snow showers could occur. The best shot for low
ceilings at area terminals will be KCOD and KCPR. Improving
conditions are expected from north to south after 09Z Thursday.

West of the Divide...KBPI/KJAC/KPNA/KRKS Routes

VFR conditions with some increasing high cloudiness is expected
today. Winds are expected to be mainly light this morning, with a
west to northwest breezy conditions developing late in the day. A
cold front is expected to sweep west/southwest across Sweetwater
County between 03Z and 06Z Thursday, with windy northeast to east
winds in wake of the front. There is a slight chance of some low
ceilings trying to develop at KRKS after 06Z Thursday, but the
overall dryness of the system should limit the chances of low
ceilings. Otherwise, VFR conditions are expected with any
precipitation remaining east of the Divide.

&&

.FIRE WEATHER...

Dry conditions and clear skies will be in place across the area
today. Light winds will also be the norm, except across the Wind
Corridor. Southwest winds will increase later this morning, from
South Pass to southern Johnson County. Expect winds of 15 to 25 mph
with gusts up to 35 mph. Minimum RH values will drop into the lower
to middle teens across southern, central and eastern portions of the
forecast area, however, critical fuels are in effect for zones 280,
283 and 289. Thus, a Red Flag Warning will be in effect for 280 and
289. Although winds will be less of a factor, zones 281, 283, 278
and 279 will have elevated fire concerns due to the low RH. A
cold front will stay east of the Divide tonight, bringing isolated
to scattered showers to northern and eastern portions. Winds will
also switch to the north and remain windy behind the front. A
strong ridge will build over the region Thursday and Friday,
keeping conditions warm and dry. Min RH values will reach critical
values again for many areas Friday, however, winds will be light.


&&

.RIW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon today to 7 PM MDT this evening for
WYZ280-289.

&&
	

Latest GFS MOS for JAC
	KJAC   GFS MOS GUIDANCE    4/25/2018  0000 UTC
DT /APR  25            /APR  26                /APR  27          /
HR   06 09 12 15 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 18 00
X/N                    61          28          64          29    67
TMP  31 27 22 33 49 58 58 48 41 36 29 40 55 63 64 52 40 35 30 58 63
DPT  23 24 21 24 23 22 22 23 26 26 24 27 27 22 22 28 31 30 28 34 31
CLD  CL CL CL CL CL FW FW CL CL CL CL CL CL CL FW CL CL CL CL CL BK
WDR  01 01 36 21 19 22 25 25 36 01 36 18 20 21 24 03 02 01 36 20 20
WSP  03 06 03 03 07 10 10 10 08 08 06 04 05 05 05 05 05 05 05 05 07
P06         0     0     0     1     0     0     1     0     0  0  2
P12                     0           1           1           0     2
Q06         0     0     0     0     0     0     0     0     0  0  0
Q12                     0           0           0           0     0
T06      0/ 0  0/ 0  0/ 0  0/ 0  0/ 0  0/ 0  1/ 0  1/ 0  0/ 0  5/ 0
T12            0/ 0        0/ 0        0/ 0        2/ 0     0/ 0
POZ   0  1  2  2  1  0  0  0  1  0  0  1  0  0  0  0  1  0  0  0  0
POS  82 88 74 61 42 22 16 44 61 69 48 39 29 22 16 23 37 54 32 21 21
TYP   S  S  S  S  R  R  R  R  S  S  R  R  R  R  R  R  R  S  R  R  R
SNW                                 0                       0
CIG   8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8  8
VIS   7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7  7
OBV   N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N  N



922
FOUS25 KWNO 250000

-----------------

KJAC   GFSX MOS GUIDANCE   4/25/2018  0000 UTC
FHR  24| 36  48| 60  72| 84  96|108 120|132 144|156 168|180 192
WED  25| THU 26| FRI 27| SAT 28| SUN 29| MON 30| TUE 01| WED 02 CLIMO
X/N  61| 28  64| 29  67| 38  65| 41  42| 35  46| 27  55| 30  59 28 55
TMP  58| 29  64| 30  63| 39  59| 42  37| 37  44| 28  52| 31  55
DPT  22| 24  22| 28  31| 35  36| 34  33| 30  30| 27  29| 28  27
CLD  CL| CL  CL| CL  CL| PC  OV| OV  OV| OV  OV| OV  OV| OV  PC
WND  10| 10   6|  5   8|  7  11| 15  27| 22  14|  9   8|  8   8
P12   0|  1   1|  0   2| 26  27| 59  58| 48  36| 24  28| 21  22999999
P24    |      1|      2|     39|     75|     57|     39|     33   999
Q12   0|  0   0|  0   0|  0   1|  4   4|  3   2|  1    |
Q24    |      0|      0|      1|      3|      1|       |
T12   1|  0   3|  1   5| 18  19| 27  14| 11  10|  3   9|  5  10
T24    |  1    |  4    | 29    | 44    | 22    | 10    | 15
PZP   4|  3   2|  0   1|  0   1|  0   1|  0   1|  0   1|  0   1
PSN  43| 38  28| 28  28| 23  20| 29  56| 52  47| 38  35| 29  26
PRS  12| 30  22| 15  13|  7   7| 23  16| 16  22| 19  23| 18  15
TYP  RS| RS  RS|  R  RS|  R   R| RS   S|  S  RS| RS  RS| RS   R
SNW    |      0|      0|      0|      0|      0|       |

	
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