Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/14/12
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
332 PM MST WED DEC 12 2012
.SHORT TERM...WEST SOUTHWEST FLOW ALOFT CURRENTLY ACROSS REGION
WITH UPPER LEVEL RIDGE OVER COLORADO. MOUNTAIN WAVE PRODUCING
GUSTY WINDS ACROSS MOUNTAINS AND ALONG FOOTHILLS...WITH GUSTS
AROUND 50 MPH OVER THE HIGHER RIDGES. ACROSS PLAINS...WAVE CLOUD
HAD DISSIPATED WHICH ALLOWED FOR DECENT MIXING. THIS ALLOWED
SOUTHWESTERLIES TO MIX TO THE SURFACE WITH SOME GUSTS TO 20 KTS.
LATEST RUC CROSS SECTION SHOWING CROSS MOUNTAIN FLOW OF 40 KTS AT
MOUNTAIN TOP INCREASING TO 45 KTS BY 00Z. SHOULD SEE GUSTY WINDS
CONTINUE ACROSS MOUNTAINS AND FOOTHILLS INTO THE EVENING WITH SOME
GUSTS TO 60 MPH POSSIBLE ACROSS THE HIGHER RIDGES. WESTERLIES
SHOULD ALSO MOVE ONTO THE ADJACENT PLAINS. UPPER LEVEL RIDGE TO
MOVE ONTO THE CENTRAL PLAINS BY MIDNIGHT WITH THE FLOW ALOFT
BECOMING MORE SOUTHWEST. MODELS SHOW THE WINDS ALOFT WEAKENING
THOUGH CROSS MOUNTAIN FLOW REMAINS AT 40 KTS AT MOUNTAIN TOP.
COULD STILL SEE SOME GUSTS ACROSS THE HIGHER RIDGES. WRF SYNTHETIC
SATELLITE IMAGERY SHOW SOME DEVELOPMENT OF A WAVE CLOUD ACROSS THE
SOUTHERN FOOTHILLS DURING THE EVENING SPREADING NORTHEAST ACROSS
THE PLAINS OVERNIGHT. ENOUGH TO MAINTAIN PARTLY CLOUDY CONDITIONS.
ON THURSDAY...SOUTHWEST FLOW ALOFT TO PREVAIL AS UPPER TROUGH
MOVES ONSHORE OVER THE WEST COAST. 600 MB WINDS 30-35 KTS WITH
MOUNTAIN TOP WINDS 20-25 KTS. NOT MUCH OF A MOUNTAIN WAVE EXPECTED
BUT APPEARS THERE WILL BE ENOUGH MIXING BY THE AFTERNOON FOR GUSTY
SOUTHWEST WINDS ACROSS THE MOUNTAINS AND FOOTHILLS. SHOULD ALSO
SEE SOUTHWESTERLIES ACROSS THE PLAINS DURING THE AFTERNOON. SHOULD
AGAIN SEE TEMPERATURES REACH THE 50S ACROSS THE PLAINS...PERHAPS
NOT AS WARM AS TODAY`S READINGS.
.LONG TERM...AN UPPER LEVEL LOW OVER SOUTHERN CALIFORNIA THURSDAY
EVENING WILL OPEN UP AND MOVE NORTHEAST OVER THE STATE BY FRIDAY
AFTERNOON. AREAS OF PRECIPITATION WILL BEGIN TO INCREASE FRIDAY
MORNING WITH SNOW IN THE MOUNTAINS AND A MIX OF RAIN AND SNOW OVER
THE PLAINS. THE 700 MB FLOW IS NOT PARTICULARLY FAVORED FOR
SIGNIFICANT ACCUMULATIONS WITH HELP FROM OROGRAPHICS...HOWEVER
GOOD QG VERTICAL VELOCITIES WILL LIKELY HAVE SOME CONVECTIVE
CHARACTERISTIC TO ADD TO ISOLATED AREAS. THE 700 MB FLOW WILL ALSO
TEND TO KEEP MOST OF THE WESTERN PLAINS...THE URBAN CORRIDOR
MOSTLY DRY WILL ALLOWING SOME SHOWERS TO OCCUR FURTHER EAST.
COOLER AIR MOVING IN WITH THE SYSTEM ALONG WITH CLOUD COVER WILL
PRODUCE MAX TEMPERATURES ABOUT 5-10 DEGREES COOLER THAN THURSDAY.
FRIDAY NIGHT INTO SATURDAY...THE SNOW WILL LIKELY CONTINUE IN THE
MOUNTAINS...ALBEIT LIGHT...WITH CLEARING CONDITIONS OVER THE
PLAINS. TOTAL SNOW ACCUMULATIONS FROM FRIDAY MORNING INTO SATURDAY
MORNING FOR THE MOUNTAINS COULD BE IN THE 3-8 INCHES...SO NO NEED
FOR ANY HIGHLIGHT RIGHT NOW. WILL CONTINUE TO MONITOR THE TRACK OF
THIS STORM.
SATURDAY NIGHT THROUGH SUNDAY WILL FEATURE TWO MORE SHORTWAVE
SYSTEMS TO KEEP A GOOD CHANCE OF SNOW FOR THE MOUNTAINS...BUT
LIKELY KEEPING THE PLAINS DRY.
STARTING SUNDAY...MODEL SOLUTIONS START TO SPREAD QUITE FAR APART
FROM EACH OTHER EVEN THOUGH THEY ARE MORE CONSISTENT IN
THEMSELVES. WILL HAVE A SLIGHT CHANCE FOR SNOW CONTINUE IN THE
MOUNTAINS THROUGH MONDAY WITH SLIGHT DRYING AFTERWARD. CONFIDENCE
IS QUITE LOW FOR THIS PERIOD HOWEVER.
&&
.AVIATION...SOUTHWESTERLIES HAVE MIXED TO THE SURFACE ACROSS THE
DENVER AIRPORTS...THOUGH THE WESTERLIES HAVEN`T MOVED INTO BJC.
LATEST RAP AND RUC STILL INDICATING A WESTERLY PUSH ACROSS AREA
00Z-02Z. WILL CONTINUE TO SHOW SOME SORT OF A WESTERLY COMPONENT
THROUGH 02Z BEFORE SOUTHWEST DRAINAGE PATTERN DEVELOPS. GUSTY
DOWNSLOPE WINDS SHOULD PREVAIL AT BJC OVERNIGHT. WAVE CLOUD COULD
REDEVELOP SOUTH AND EAST OF THE AREA OVERNIGHT...THOUGH CEILINGS
WILL REMAIN ABOVE 14000 FEET AGL. ON THURSDAY...SOUTHERLY
WINDS TO PREVAIL WITH MORE OF A WEST SOUTHWEST COMPONENT AT BJC.
WINDS COULD BECOME MORE SOUTHEAST AT DEN AND APA.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....KRIEDERMAN
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
939 AM MST WED DEC 12 2012
.UPDATE...
&&
.SHORT TERM...MODERATE WEST SOUTHWEST FLOW ALOFT CURRENTLY ACROSS
REGION WITH INVERSION AT MOUNTAIN TOP. MODEL CROSS SECTIONS SHOW WEAK
MOUNTAIN WAVE TO PERSIST THROUGH THE DAY BEFORE WEAKENING DURING
THE EVENING. RUC SHOWS CROSS MOUNTAIN FLOW OF 40-45 KTS AT
MOUNTAIN TOP THROUGH 00Z. THIS COMBINED WITH LEE TROUGH ALONG
FOOTHILLS WILL KEEP GUSTY WINDS GOING OVER THE MOUNTAINS AND
ALONG AND NEAR FOOTHILLS FOR MUCH OF THE DAY WITH SOME GUSTS
AROUND 50-55 MPH POSSIBLE...MAINLY HIGHER RIDGES. LATEST RUC AND
HRRR SHOW WESTERLY WINDS PUSHING ACROSS THE URBAN CORRIDOR AFTER
21Z. FAIRLY EXTENSIVE WAVE CLOUD CURRENTLY ALONG THE FRONT
RANGE...SHOWING SIGNS OF MOVING EAST. LATEST WRF SYNTHETIC
SATELLITE IMAGERY SHOWS THIS TREND WITH DECREASING CLOUDS ALONG
URBAN CORRIDOR. THE CLEARING SKIES AND DOWNSLOPE WINDS SHOULD
ALLOW TEMPERATURES ACROSS PLAINS TO WARM INTO THE 50S...WITH MID
TO UPPER 40S IN THE LOW LYING AREAS ALONG THE SOUTH PLATTE RIVER.
OVERALL...CURRENT FORECASTS SEEM IN ORDER...ONLY MINOR CHANGES AT
THIS TIME.
.AVIATION...IN GENERAL...CURRENT TAF TRENDS LOOK REASONABLE. MAY
NEED MORE OF A WESTERLY COMPONENT AT DIA AROUND 22Z AS LATEST RAP
AND HRRR SHOW A WESTERLY PUSH ACROSS THE DENVER AREA. APA MAY
REMAIN MORE SOUTHWEST. SHOULD SEE MORE OF A WESTERLY COMPONENT AT
BJC BY THE AFTERNOON AS DOWNSLOPE WINDS PUSH OFF THE FOOTHILLS.
&&
.PREV DISCUSSION... /ISSUED 223 AM MST WED DEC 12 2012/
SHORT TERM...A MODERATE WEST TO SOUTHWESTERLY FLOW ALOFT WILL BE
OVER THE CWFA UNDER A RIDGE OF HIGH PRESSURE ALOFT. A LEE TROUGH
ALONG THE FRONT RANGE COUPLED WITH A WEAK MOUNTAIN WAVE DEPICTED
IN THE SPATIAL CROSS-SECTIONS WILL ALLOW FOR PERSISTENT DOWNSLOPE
WINDS ALONG THE FRONT RANGE. STRONGEST WINDS WILL BE CONFINED TO
THE MOUNTAINS EAST OF THE CONTINENTAL DIVIDE AND HIGHER FOOTHILLS.
STRONGER GUSTS IN THE 45 TO 55 MPH RANGE SO NO HIGHLIGHTS NEEDED.
TEMPERATURES THIS AFTERNOON WILL WARM 10-15 DEGREES OVER MONDAY SO
WELL ABOVE SEASONAL NORMALS. SYNTHETIC SATELLITE DEPICTS ENOUGH
UPPER LEVEL MOISTURE TO CONTINUE WITH PARTLY CLOUDY FOR BOTH
PERIODS.
LONG TERM...MODELS HAVE SOUTHWESTERLY FLOW ALOFT FOR THE FORECAST
AREA THURSDAY THROUGH MIDDAY FRIDAY. AN UPPER TROUGH MOVES INTO
COLORADO BY FRIDAY AFTERNOON AND ACROSS THE FORECAST AREA BY LATE
FRIDAY NIGHT. THE GFS IS A HALF A PERIOD SLOWER WITH THIS FEATURE
COMPARED TO THE NAM. THERE IS WEAK UPWARD Q-G VERTICAL VELOCITY
PROGGED FOR THE CWA THURSDAY AND THURSDAY NIGHT. IT GETS STRONGER
ON FRIDAY. DOWNWARD MOTION IS PROGGED MUCH OF FRIDAY NIGHT. THE
BOUNDARY LAYER FLOW IS MAINLY DOWNSLOPING SOUTHWESTERLY THURSDAY
AND THURSDAY NIGHT. BY FRIDAY...THE LOW LEVEL FLOW IS EASTERLY
..THEN NORTHEASTERLY FRIDAY AFTERNOON INTO THE EVENING. LATER
FRIDAY NIGHT THE LOW LEVEL WINDS ARE NORTH-NORTHWESTERLY. FOR
MOISTURE...THURSDAY IS PRETTY DRY...SO IS MUCH OF THURSDAY NIGHT.
MOISTURE INCREASES BY EARLY FRIDAY MORNING. MOISTURE GETS PRETTY
DEEP FRIDAY...THE BEST OVER THE MOUNTAINS. ALTHOUGH THE NAM SHOWS
PRETTY DEEP MOISTURE OVER THE PLAINS...THE GFS AND ECMWF LESS.
MOISTURE STAYS PRETTY DEEP OVER THE MOUNTAINS FRIDAY EVENING...
THEN DECREASES. THERE IS NO MEASURABLE PRECIPITATION PROGGED ON
THE QPF FIELDS THURSDAY OR THURSDAY NIGHT. ALL THE MODELS HAVE
MEASURABLE PRECIPITATION FRIDAY AND FRIDAY EVENING...BUT AMOUNTS
ARE QUITE LIGHT...EVEN IN THE MOUNTAINS. THE NAM SHOWS THE WIDEST
COVERAGE OVER THE PLAINS...BUT AGAIN...AMOUNTS ARE MEAGER. FOR
POPS...DRY THURSDAY AND THURSDAY NIGHT FOR ALL AREAS. WILL GO WITH
30-50%S IN THE MOUNTAINS FRIDAY AND FRIDAY NIGHT. THE HELP FROM
OROGRAPHICS WILL BE POOR FRIDAY...BUT WILL GET A BIT BETTER FRIDAY
NIGHT. FOR THE PLAINS WILL GO WITH 10-20%S FRIDAY. FOR TEMPERATURES
..THURSDAY`S HIGHS LOOK SIMILAR TO WEDNESDAY`S. FRIDAY`S HIGHS
COOL OFF 2-5 C. FOR THE LATER DAYS...SATURDAY THROUGH TUESDAY...
MODELS HAVE A BRIEF WEAK UPPER RIDGE ON SATURDAY...THEN THE NEXT
TROUGH MOVES ACROSS LATE SATURDAY INTO SUNDAY MORNING. THEN
ANOTHER RIDGE SUNDAY...WITH ANOTHER WEAK TROUGH LATE SUNDAY NIGHT
INTO MONDAY MORNING. BY MID DAY MONDAY...CONTINUING THROUGH
TUESDAY...STRONG NORTHWESTERLY FLOW ALOFT IS PROGGED. WILL NEED
MOUNTAIN POPS SATURDAY THROUGH MONDAY...THEN DRY.
AVIATION...VFR CONDITIONS OVER THE NEXT 24 HRS. WINDS WILL
GENERALLY CONTINUE WITH SSWLY COMPONENT THROUGH THE PERIOD WITH A
PERSISTENT LEE TROUGH ALONG THE FRONT RANGE. WL CONTINUE TO
MENTION STRONGER WLY WINDS AT KBJC AS SOME DOWNSLOPE COMPONENT
PRESENT NEAR THE FOOTHILLS.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....RJK
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
930 PM EST THU DEC 13 2012
.SYNOPSIS...
HIGH PRESSURE WILL PREVAIL ACROSS THE REGION THROUGH SATURDAY
BEFORE MOVING OFFSHORE SUNDAY IN ADVANCE OF A COLD FRONT. THE
FRONT WILL MOVE THROUGH THE AREA EARLY NEXT WEEK WITH HIGH
PRESSURE REBUILDING BEHIND IT.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
THE CLEARING LINE IS APPROACHING THE I-16 CORRIDOR AND WILL PASS
SOUTH TO THE ALTAMAHA RIVER BY MIDNIGHT. CLOUDS CONTINUE TO HUG
THE COAST...BUT EXPECT THESE WILL BEGIN TO PUSH OFFSHORE AFTER
MIDNIGHT AS THE FLOW AT 925MB BACKS MORE NORTHERLY. SHOULD SEE A
MOSTLY CLEAR SKY DOMINATE FOR MUCH OF THE NIGHT...ALTHOUGH THE
LAST FEW RUNS OF THE RAP SO SHOW A SLUG OF MOISTURE BENDING BACK
INLAND ACROSS NORTH COASTAL GEORGIA AFTER 4-5 AM. WILL SHOW PARTLY
CLOUDY SKIES RETURNING ACROSS THE GEORGIA COASTAL COUNTIES PRIOR
TO SUNRISE AS A RESULT.
THE BOUNDARY LAYER HAS DECOUPLED INLAND WITH CALM WIND BEING
REPORTED A NUMBER OF LOCATIONS...BUT WINDS REMAIN SOMEWHAT
ELEVATED AT THE COAST. THIS COUPLED WITH LINGERING CLOUD
INFLUENCES IS YIELDING A SOMEWHAT UNEVEN THERMAL DECLINE THIS
EVENING. INCOMING GUIDANCE IS TRENDING A BIT COOLER WELL INLAND
WHERE SOLID RADIATIONAL CONDITIONS ARE EXPECTED...SO WILL NUDGE
LOWS DOWN 1-2 DEGREES. WARMER CONDITIONS WILL OCCUR OVER THE
COASTAL COUNTIES WHERE FULL BOUNDARY LAYER DECOUPLING APPEARS
UNLIKELY. LOWS WILL RANGE FROM THE LOWER-MID 30S INLAND TO THE
UPPER 30S-LOWER 40S AT THE COAST.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/...
BROAD UPPER RIDGING FRIDAY INTO SATURDAY WILL ALLOW FOR A PRONOUNCED
WARMING TREND WITH DRY WEATHER. SOME LINGERING CLOUDINESS ACROSS
SOUTHEAST GEORGIA FRIDAY MORNING SHOULD QUICKLY ERODE ALLOWING FOR A
MOSTLY SUNNY DAY WITH HIGHS IN THE MIDDLE 60S. JET CIRRUS AS WELL AS
SOME LOW-LEVEL STRATOCU WILL OVERSPREAD THE REGION FRIDAY NIGHT INTO
SATURDAY AS THE SURFACE HIGH SHIFTS OFFSHORE BUT THICKNESSES SHOULD
STILL ALLOW FOR HIGHS TO REACH THE UPPER 60S.
THE PATTERN SHIFTS ON SUNDAY AS A COMPLEX UPPER JET MOVES INTO THE
EASTERN UNITED STATES AND A SERIES OF SHORTWAVE DISTURBANCES IN THE
MID-LEVELS LIFT OUT OF THE GULF COAST REGION. ALTHOUGH THE PRIMARY
COLD FRONT SHOULD STAY TO THE WEST...LOW-LEVEL MOISTURE AND
ISENTROPIC ASCENT WILL BRING A CHANCE FOR RAIN TO THE AREA. WE STUCK
WITH JUST 20-30 POPS AT THIS POINT GIVEN CONSIDERABLE MODEL
DIFFERENCES. STRONG WARM ADVECTION WILL PUSH TEMPS INTO THE LOWER
70S DESPITE MOSTLY CLOUDY SKIES.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THE EXTENDED PORTION OF THE FORECAST LOOKS TO BE AN ACTIVE PERIOD
STARTING WITH A WELL DEFINED COLD FRONT MOVING INTO THE AREA ON
MONDAY. THE GFS FEATURES A MUCH STRONGER SHORTWAVE THAN THE
ECMWF...AND THUS HAS A MUCH STRONGER AND CLEANER FRONTAL PASSAGE
LATE MONDAY INTO TUESDAY. IN FACT...GIVEN THE POTENT WIND
FIELD...500 MB WINDS ON THE ORDER 75 KTS...IF ANY SURFACE
DESTABILIZATION TAKES PLACE WE COULD SEE A THUNDERSTORM THREAT. THIS
WILL LARGELY BE DEPENDENT ON THE AMOUNT OF CLOUD COVER MONDAY
AFTERNOON AND CONFIDENCE IS STILL LOW AT THIS POINT AS TO THE
DETAILS. THE MODELS HAVE COME INTO BETTER AGREEMENT AFTER
MONDAY...WITH THE ECMWF NOW FEATURING A FURTHER NORTH TRACK OF THE
VIGOROUS TROUGH THROUGH MID WEEK. THE EC NOW KICKS OFF CYCLOGENESIS
OFF THE NC OUTER BANKS TUESDAY NIGHT INSTEAD OF ALONG THE GULF COAST
AS BEFORE. THIS WOULD RESULT IN A DRIER FORECAST BEYOND MONDAY...AND
POPS HAVE BEEN TRENDED DOWNWARD IN THIS TIME PERIOD. HIGH PRESSURE
THEN BUILDS INTO THE REGION WEDNESDAY INTO THURSDAY. THE HIGHEST
POPS FOR THE EXTENDED HAVE BEEN PLACED WITH THE COLD FRONT ON MONDAY
WITH A DECREASING TREND THEREAFTER.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
KCHS...CLEARING LINE WILL CLEAR THE TERMINAL BETWEEN 00-01Z. EXPECT
VFR CONDITIONS TO PREVAIL FOR THE REMAINDER OF THE TAF PERIOD.
KSAV...LOW-END MVFR CIGS WILL PERSIST FOR A FEW MORE HOURS WITH
THE CLEARING LINE EXPECTED TO CROSS THE TERMINAL AROUND 04Z.
SHOULD SEE VFR CONDITIONS DOMINATE THEREAFTER.
EXTENDED AVIATION OUTLOOK...FLIGHT RESTRICTIONS WILL BECOME
INCREASINGLY LIKELY SUNDAY THROUGH TUESDAY AS A COLD FRONT
APPROACHES WITH LOWER CLOUDS AND RAIN.
&&
.MARINE...
TONIGHT...BUOY AND PILOT BOAT REPORTS INDICATE BOTH WINDS AND SEAS
HAVE DROPPED BELOW SMALL CRAFT ADVISORY THRESHOLDS ACROSS ALL
NEARSHORE ZONES. WILL CANCEL THE SMALL CRAFT ADVISORY THERE...BUT
MAINTAIN IT FOR THE GEORGIA OFFSHORE ZONES OVERNIGHT WHERE MORE
ELEVATED WINDS AND SEAS WILL BE FOUND.
FRIDAY THROUGH MONDAY...NORTHEAST WINDS WILL CONTINUE FRIDAY INTO
SATURDAY BUT THE GRADIENT SHOULD BE RELAXING SO SEAS WILL BE
COMING DOWN. THE SMALL CRAFT FOR THE OFFSHORE GA WATERS SHOULD BE
ABLE TO DROP OFF EARLY SATURDAY MORNING. A WELL DEFINED COLD FRONT
IS EXPECTED TO AFFECT THE AREA ON MONDAY WITH STRENGTHENING LOW
LEVEL WIND FIELDS. SMALL CRAFT ADVISORIES MAY EVENTUALLY BE NEEDED
FOR PORTIONS OF THE LOCAL WATERS DURING THIS TIME.
&&
.TIDES/COASTAL FLOODING...
COASTAL FLOODING IS ANOTHER SURE BET ON FRIDAY MORNING GIVEN THE NNE
WIND FLOW AND ABOVE-NORMAL TIDE LEVELS. WE ISSUED A COASTAL FLOOD
ADVISORY FOR ALL COASTAL AREAS. DO NOT THINK A COASTAL FLOOD WATCH
IS IN ORDER BECAUSE THE WIND SPEEDS ARE SHOWING A STEADY DECLINE SO
THE SURGE SHOULD NOT BE ANY HIGHER THAN THIS MORNING. MAINTAINED
MENTION IN THE HAZARDOUS WEATHER OUTLOOK FOR SATURDAY MORNING AS
WELL.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...COASTAL FLOOD ADVISORY FROM 5 AM TO 11 AM EST FRIDAY FOR
GAZ117-119-139-141.
SC...COASTAL FLOOD ADVISORY FROM 5 AM TO 11 AM EST FRIDAY FOR
SCZ048>052.
MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EST SATURDAY FOR AMZ374.
&&
$$
ST
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
307 AM EST WED DEC 12 2012
.Short Term (Today through Thursday)...
Issued at 245 AM EST Wed Dec 12 2012
Clear skies were noted across the forecast area. This combined with
light winds has allowed good radiational cooling to commence.
Temperatures across the region are currently in the lower to middle
20s and temps should continue to drop through the remainder of the
overnight hours. Have utilized the LMK temperature low temp study
data for lows this morning. Feel that lower 20s will be the rule,
but our typical colder locations will likely drop into the upper
teens.
High pressure at the surface will remain in control of the weather
pattern for today with mostly sunny skies expected. Upper level
currently across Texas will head eastward and pass to our south
today. Mid level heights will rise behind the front which should
allow for temperatures to be a bit warmer than what we saw
yesterday. Generally went close to the weighted model average which
yields afternoon highs in the lower 40s across the northeast
sections and middle 40s across the central and southwest sections.
Overall, this is a little on the cool side of the guidance envelope
for today.
Another clear night is expected tonight with light winds. This
should result in another night of good radiational cooling with
overnight lows dropping back into the lower-middle 20s. Again, our
typical cold spots and valley locations probably will drop back into
the upper teens.
As the next mid level wave drops into the western CONUS on Thursday,
we`ll see another modest rise in mid level heights across the
region. This combined with surface high pressure will result in
another mostly sunny day and milder temperatures. Highs should
range from the mid-upper 40s in the northeast/Bluegrass to the lower
50s in the central and southwest sections.
.Long Term (Thursday Night through Tuesday)...
Issued at 305 AM EST Wed Dec 12 2012
The long term will start out with an elongated area of surface high
pressure stretched along the east coast and southerly winds. Aloft
we will have weak ridging. With this pattern the dry weather will
continue Thursday night and Friday before becoming unsettled once
again.
Friday night into Saturday a low pressure system will move out of
the Plains and into the upper Midwest. Precipitation will begin to
move into the area after midnight Friday. Rain chances will increase
through the day as the system tracks northeast. Rains look to taper
off ahead of the cold frontal passage, which will not be until
Sunday. Will hang on to slight chance to chance pops through Sunday.
Temperatures will start out cold on Friday in the mid 20s to lower
30s. However, with southerly winds and sunny skies, they will
rebound into the lower to mid 50s. For Saturday temps will be
similar, despite more cloud cover and rain as strong warm air
advection will continue. Saturday night through Sunday temperatures
will be a bit trickier and will depend on how fast the cooler air
moves in behind the cold front.
Beyond Sunday the models diverge in their solutions. A couple of
shortwaves and surface lows will cross the area. However, there s
quite a bit of spread in the track and timing of these systems. For
now have leaned toward the ECMWF and toward the previous forecast
for consistency`s sake. This will keep Monday and Monday night dry
before precip moves back in on Tuesday, courtesy of a low passing
south of the forecast area.
Temperatures to start the work week will be cooler than over the
weekend. Highs will be in the 40s with lows in the 30s.
&&
.Aviation (06Z TAF Issuance)...
Issued at 1213 AM EST Wed Dec 12 2012
VFR conditions are expected at all the terminals as surface high
pressure continues to build into the region. Light and variable
winds are expected through the overnight hours. As temperatures
fall overnight, we should see some close T/Td spreads. While the
guidance is still a no go on fog, latest WRF ABI simulated satellite
shows a bit of valley fog developing in the preferred locales.
Latest RUC 13 progs also show some light haze with visibilities
dropping to around 6-7 miles overnight mainly across southern KY.
For now, still plan on keeping things VFR in the upcoming forecast
but will continue to monitor things overnight.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Short Term.......MJ
Long Term........EER
Aviation.........MJ
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1213 AM EST WED DEC 12 2012
...Updated Aviation Discussion...
.Forecast Update...
Issued at 950 PM EST Tue Dec 11 2012
Main update for tonight was low temperatures. Many area
observations were already into the mid 20s to lower 30s as of 230Z
which wasn`t too far off from previously forecast min temps.
Therefore, took most locations down a few degrees for tonight, and
took our valley/rural locations down 3-5 degrees as these areas will
really cool off with a good long rad cooling night ahead. Thus,
this puts most locations in the low to mid 20s for lows with our
coldest locations dipping into the upper teens.
Did investigate the possibility for some very light fog overnight
due to the excellent rad cooling, but believe the sfc is a bit too
dry and dewpts will probably start to fall slightly with
temperatures toward sunrise.
&&
.Short Term (Tonight through Wednesday night)...
Issued at 150 PM EST Tue Dec 11 2012
Lingering cloud shield over the Ohio Valley is finally eroding from
west to east, with mostly clear skies west of I-65, and partly to
mostly cloudy farther east. Expect these clouds to be out of the
Bluegrass region around sunset.
The next couple days will be dominated by high pressure, currently
centered Arkansas with the ridge axis extending up through Kentucky
into West Virginia. Pressures will rise in response to a building
upper ridge, but the surface ridge will mainly become more elongated
and not move much at all. As a result, expect favorable radiational
cooling conditions the next 2 nights, with lows in the 20s in most
locations both nights. Progged low-level thicknesses and 850mb temps
support Wednesday max temps at least 6 degrees warmer than today.
Will go out on a limb that we will reach 40 this afternoon, which
puts highs in the mid to upper 40s, which is actually just on the
low end of MOS guidance.
.Long Term (Thursday through Tuesday)...
Issued at 145 PM EST Tue Dec 11 2012
At the start of this period, a strong trough will start to control
west coast, which will promote ridging across the south and
southeast CONUS into Saturday. While our area will be under the
influence of broad and dry southwest flow aloft into late Friday,
the pattern will change and become more active. Guidance continues
to indicate a couple systems ejecting out of the west coast and
moving east through the Ohio Valley Saturday through Tuesday. These
systems are of Pacific origin and never really tap into the colder
air across Canada due to a progged blocking pattern. Forecast
confidence is fairly high through Saturday as models are handling
the first system fairly well.
Surface high pressure will shift east across the Ohio Valley and
settle in the southeastern CONUS by Saturday morning. Surface winds
will transition to southerly and become breezy by Saturday as a
surface low pressure system moves through Kansas, Missouri, and into
northern Illinois. Dry conditions, mostly clear skies, and warming
temperatures are expected through Friday. High temperatures will
warm into the low and mid 50s by Friday.
Clouds and precip chances will increase heading into the weekend as
a low pressure system passes by to the north. Since yesterday, the
GFS solution has trended much closer to the ECMWF and NAEFS mean,
which is why forecast confidence is fairly high through Saturday.
The trailing cold front is projected to sweep through the forecast
area Saturday night into Sunday, with another shot at area-wide rain
showers, perhaps a rumble of thunder with marginal instability.
Temperatures will continue to warm Saturday ahead of the cold front,
which is currently forecast to be our warmest day. Highs in the mid
50s in the north to around 60 degrees in the south appear reasonable
on breezy southerly flow, even with increasing clouds and precip
chances. Temperatures will cool slightly Sunday through Tuesday,
becoming closer to mid-December normals. A brief dry period is
expected late Sunday night through Monday night, as high pressure
and ridging aloft pass through the Ohio Valley. Cloud cover should
start to break up some late Sunday night, but a thin layer of low
stratus could linger just below the inversion.
Models diverge with the second system to cross our area Tuesday,
mainly because there are differences with the progged blocking
pattern across Canada. Spread is noticeable within the ensembles.
Either way, guidance agrees rain chances will increase for Tuesday,
but the devil is in the details. As mentioned in the previous
forecast discussion, this forecast will lean toward the ECMWF
solution. So, it appears a deep and slow moving low pressure system
will track across the central CONUS, with a surface low projected to
slide through the Ohio and Tennessee Valleys late Tuesday.
&&
.Aviation (06Z TAF Issuance)...
Issued at 1213 AM EST Wed Dec 12 2012
VFR conditions are expected at all the terminals as surface high
pressure continues to build into the region. Light and variable
winds are expected through the overnight hours. As temperatures
fall overnight, we should see some close T/Td spreads. While the
guidance is still a no go on fog, latest WRF ABI simulated satellite
shows a bit of valley fog developing in the preferred locales.
Latest RUC 13 progs also show some light haze with visibilities
dropping to around 6-7 miles overnight mainly across southern KY.
For now, still plan on keeping things VFR in the upcoming forecast
but will continue to monitor things overnight.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........AMS
Short Term.......RAS
Long Term........MJP
Aviation.........MJ
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1219 AM EST WED DEC 12 2012
.SYNOPSIS...
A FRONTAL BOUNDARY STALLS OVER THE EASTERN CAROLINAS TONIGHT AS
HIGH PRESSURE SLOWLY BUILDS IN FROM THE NORTHWEST. A WAVE OF LOW
PRESSURE WILL DEVELOP ALONG THE FRONT WEDNESDAY...PUSHING FARTHER
OFFSHORE WEDNESDAY NIGHT INTO THURSDAY. HIGH PRESSURE REMAINS IN
PLACE OVER THE MID ATLANTIC THROUGH THE END OF THIS WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
A COLD FRNT INTO ERN NC WHILE HI PRES SLOWLY BLDS IN FROM THE NW.
STRONG LO-LVL INVERSION AND ASSOCIATED MOISTURE WILL KEEP SKIES
MSTLY CLDY THIS EVENG AND OVRNGT...WITH THE LO STRATUS AND HI
TEMP-DEWPT SPREADS PREVENTING FOG FORMATION. STRONG SW FLOW ABOVE
THE INVERSION MAY PROVIDE JUST ENUF (ISENTROPIC) LIFT TO LEAD TO
-RA OVER EXTREME SE VA/NE NC AS MOST MODELS INDICATE...POPS 30% AT
ORF...50% OVER NE NC. LOOKING AT RAP MODEL AND OBSERVATIONS WILL
DELAY THE HIGHER POPS UNTIL AFTER MIDNIGHT AS RAIN ONLY SLOWLY
WORKING NORTHEAST. RAIN CHCS INCREASE TO LIKELY OVER THESE AREAS
INTO WED AS THREAT FOR OVERRUNING PRECIP CONTINUES AND A WAVE OF
LO PRES DEVELOPS ALONG THE STALLED FRNT. TOTAL AMOUNTS SHUD STAY
BLO ONE- QUARTER OF AN INCH DUE TO WEAK LIFT. ONLY A 20% CHC OF
RAIN MAKING IN UP TO RIC/SBY. OTHERWISE...MSTLY CLDY TO CLDY SKIES
FOR THE DAY. LO TEMPS TNGT RANGE FROM THE LWR 30S NW TO LWR 40S
SE...WITH HI TEMPS WED IN THE UPR 40S TO LWR 50S.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY/...
SOME -RA MAY LINGER INTO WED NGT AS LO PRES AND ASSOCIATED FRNTAL
BNDRY PUSH FARTHER OFFSHORE. CONFINED POPS TO SE VA/NE NC AFTER
MIDNGT. DECREASING CLDS AS WELL (TO MSTLY CLR) AS LO TEMPS RANGE
FROM NEAR 30 OVER THE PIEDMONT TO NEAR 40 ALONG THE COAST. ~1030
MB SFC HI PRES BLDS DIRECTLY OVER THE MID-ATLANTIC THU...AND
STAYING PUT INTO FRI. THIS WILL LEAD TO A SNY SKY AND SEASONABLE
TEMPS WITH HIGHS IN THE LWR TO MID 50S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
SFC HI PRES INVOF MDATLC STATES FRI NGT IS SLO TO WEAKEN...DRIFT
OFF THE CST SAT. MDT SFC LO PRES TRACKS INTO/THROUGH THE LAKES RGN
SUN INTO MON...PUSHING ASSOCD CDFNT ACRS THE MDATLC RGN. PCPN
PTNTL LOOKS LESS THAN THAT FM PAST CPL DAYS...HAVE CAPPED POPS ABT
30%). DRYING OUT/SEASONABLE WX FM MON AFTN THROUGH TUE. ANOTHER
STORM SYS MAY APPROACH FM THE WSW BY MID NEXT WK.
MILDER SAT...BFR COOLING DOWN (TO AT OR SLGTLY BLO NRML) SUN
THROUGH TUE.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
LOW PRESSURE MOVING NE ALONG THE COAST WILL KEEP THE NE WIND FLOW...
BKN-OVC MVFR CIGS ACROSS SERN TAF SITES THRU MOST OF THIS FCST PRD.
LATEST SUITE OF MODELS INDCT LGHT RAIN OVRSPRDG NE NC CNTYS TOWARD
12Z AND LIFTG NE TOWARD ORF BY 15Z. AIRMASS TO DRY TO THE N TO SPRT
ANY PCPN REACHING THE GRND...ALTHOUGH THERE MAY BE SOME SPRNKLS AT
PHF. ADDED SOME GUSTS UP TO 20 KTS AT ECG/ORF AFTER 12Z DUE TO
TIGHTENING PRES GRDNT.
IMPROVING CNDTNS EXPECTED AFTR 00Z AS LOW PRS PULLS FRTHR OFFSHORE
AND HIGH PRS BUILDS IN BEHIND IT. VFR / DRY WX XPCTD THURS THRU SUN.
&&
.MARINE...
FNTL BNDRY HAS STALLED JUST OFF CSTL CAROLINAS...AND WILL RMN NRLY
STNRY INTO THU. WK SFC LO PRES DVLPS...AND EVENTUALLY TRACKS ENE
ALG THE BNDRY...WHILE MDT SFC HI PRES SETTLES INVOF NE CONUS. THE
RESULT WILL BE A PD OF MDT NNE WNDS (GUSTS TO 25-30 KT
PSBL...HIGHEST ON THE OCN)...AND ASSOCD BUILDING WAVES/SEAS (ESP NR
THE MOUTH OF THE BAY...AND CAPE CHARLES LGT ON S). SCAS WILL RMN
UP ON THE SRN OCN WTRS THROUGH THU...AND WILL RAISE SCAS ON THE
SRN BAY AND SND FOR WED MRNG THROUGH THU. HI PRES EVENTUALLY
BUILDS OVR THE WTRS LT WK...AND WEAKENS ERY IN THE WKND...BRINGING
LWRG WNDS AND WAVES/SEAS.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 6 PM EST
THURSDAY FOR ANZ632>634-654.
SMALL CRAFT ADVISORY UNTIL 6 PM EST THURSDAY FOR ANZ656-658.
&&
$$
SYNOPSIS...MAS
NEAR TERM...MAS/JAB
SHORT TERM...MAS
LONG TERM...ALB
AVIATION...MPR
MARINE...ALB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
428 PM EST WED DEC 12 2012
.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 427 PM EST WED DEC 12 2012
WATER VAPOR LOOP AND RUC ANALYSIS SHOWS AN AMPLIFIED TROF OFF THE
WEST COAST WITH BROAD TROUGH CENTERED OVER HUDSON BAY DOMINATING
MUCH OF CANADA. AT THE SFC...A STATIONARY FRONT IS DRAPED OVER NORTH
DAKOTA...NRN MN INTO WRN UPR MI. A SHORTWAVE MOVING ACROSS SOUTHERN
CANADA ALONG WITH ITS ASSOC MID-LVL Q-VECT CONV AND 800 MB FGEN HAS
SUPPORTED AN AREA OF LIGHT SNOW THIS AFTERNOON OVER SRN MANITOBA AND
WRN ONTARIO.
TONIGHT...BEST FGEN FORCING AND Q-VECT CONV WITH SRN CANADA
SHORTWAVE IS FCST BY MODELS TO STAY MAINLY NORTH OF THE CWA TONIGHT.
THUS...IT ALSO MAKES SENSE THAT MODEL QPF ALSO STAYS MAINLY NORTH OF
THE AREA. MAINTAINED SLGT CHC POPS OVER THE TIP OF THE KEWEENAW AND
NRN LAKE SUPERIOR AS WEAK FORCING COULD BRUSH THESE AREAS WITH LIGHT
SNOW AND POSSIBLY DZ/FZDZ AS THERE IS A DRY LAYER ALOFT WHICH COULD
TEMPORARILY DISRUPT ICE CRYSTAL NUCLEATION. TEMPS SHOULDN`T DROP
MUCH TONIGHT UNDER CLOUDS AND INCREASING BLYR WINDS. EXPECT LOWS
FROM THE MID 20S INTERIOR WEST TO THE UPPER 20S/LOWER 30S
ELSEWHERE.
THURSDAY...A 120 KT 3H JET STREAK STREAMING EAST FROM THE CENTRAL
ROCKIES COMBINED WITH INCREASING 850-800 MB FGEN IN LEFT EXIT REGION
OF JET HAVE MOST MODELS SUPPORTING A NARROW BAND OF PCPN OVER THE
KEWEENAW PENINSULA LATE THU MORNING INTO EARLY AFTERNOON. CONTINUED
DRY LAYER AT MID-LVLS MAY DISRUPT ICE CRYSTAL NUCLEATION TO SUPPORT
SOME DZ/FZDZ MIXING IN WITH LIGHT SNOW. EXPECT ONLY A DUSTING OF
SNOW (HALF INCH OF LESS) OVER THE KEWEENAW AND MAINTAINED JUST HIGH
CHC POPS FOR NOW.
.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 427 PM EST WED DEC 12 2012
A MORE ACTIVE PATTERN LOOKS TO BE DEVELOPING BY THE END OF THE
WEEK...WITH THE MAIN FOCUS ON A POTENTIAL FOR MODERATE SNOWFALL
ACROSS MUCH OF THE AREA ON SATURDAY...AND THEN LIGHTER SNOW LASTING
INTO NEXT WEEK.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...THE LARGE SCALE FLOW WILL BE
GENERALLY ZONAL OVER THE GREAT LAKES REGION SOUTH OF A BROAD
MID-LEVEL LOW ACROSS HUDSON BAY AND NORTHERN QUEBEC. MEANWHILE...A
WEAK SHORTWAVE TROUGH WILL BE MOVING ESE ACROSS SOUTHERN MANITOBA
INTO WESTERN ONTARIO...AND A DEEP TROUGH WILL BE MOVING ONSHORE IN
CENTRAL AND SOUTHERN CA. THE DEEP WESTERN TROUGH WILL BE THE FOCUS
FOR SATURDAY ONWARD. BEFORE THEN...THE SHORTWAVE TROUGH IN SOUTHERN
CANADA WILL TRACK ACROSS WESTERN ONTARIO THURSDAY NIGHT...AND INTO
EASTERN ONTARIO BY FRIDAY AFTERNOON. INFLUENCE OF THIS TROUGH IS A
BIT WEAK ACROSS UPPER MI...AND MID-RANGE MODELS HAVE SOME
DISAGREEMENT ON PRECIP CHANCES. MID/UPPER FORCING IS NOT IMPRESSIVE
BY ANY MEANS UNTIL THE RIGHT ENTRANCE OF A 120KT UPPER JET CROSSES
THE CWA FRIDAY MORNING. BY THIS TIME...THE MID-LEVEL TROUGH WILL
ALMOST BE THROUGH THE AREA...WITH MID-LEVEL SUBSIDENCE/DRYING TAKING
HOLD. HOWEVER...LOW-LEVEL MOISTURE LINGERS...ESPECIALLY ACROSS THE
NORTHERN HALF OF THE CWA. WIND IS RATHER LIGHT AND VARIABLE THURSDAY
NIGHT THROUGH FRIDAY MORNING...BUT FAVORABLE DIRECTION IS BETWEEN N
AND E. WILL KEEP GENERAL SLIGHT CHANCE OF FZDZ NORTH...AND HAVE
EXPANDED IT SLIGHTLY TO ACCOUNT FOR TERRAIN EFFECTS.
OVERALL...EXPECT THE BEST CHANCE OF FZDZ TO BE LATE THURSDAY NIGHT
BEFORE DIMINISHING FRIDAY MORNING AS WINDS VEER TO THE SE.
BY FRIDAY EVENING...LOW LEVEL MOISTURE ADVECTING NORTHWARD AHEAD OF
THE NEXT SYSTEM WILL BRING ANOTHER POTENTIAL FOR FREEZING
DRIZZLE...THIS TIME ACROSS THE SOUTH-CENTRAL. SOUTHEAST WINDS OFF OF
LAKE MICHIGAN WILL ASSIST WITH THE MOISTURE SUPPLY...BUT THE
MOISTURE WILL BE SHALLOW (2KFT) AS A RESULT OF DRYING/SUBSIDENCE
UNDER A DEPARTING RIDGE. HAVE MENTIONED A SLIGHT CHANCE OF FREEZING
DRIZZLE IN THE HIGHER TERRAIN ACROSS THE SOUTH-CENTRAL...MAINLY
FOCUSED IN DICKINSON AND SOUTHERN MARQUETTE COUNTIES. INCREASING
CLOUD COVER COMBINED WITH STRENGTHENING WINDS SHOULD RESULT IN A
STEADY TEMP RISE THROUGHOUT THE NIGHT...WITH LOCATIONS ALONG LAKE
MICHIGAN REACHING ABOVE FREEZING BY DAY BREAK.
SATURDAY...RATHER COMPLICATED FORECAST CONCERNING THE POTENTIAL FOR
A STRONG LOW PRESSURE SYSTEM MOVING INTO THE AREA SATURDAY.
CONFIDENCE IS RUNNING LOW WITH THIS SYSTEM ATTM FOR SEVERAL REASONS.
FIRST...THE MID-LEVEL TROUGH IS STILL BARRELING SOUTHWARD ALONG THE
CA COAST THIS AFTERNOON...SO WHERE IT MAKES AN EASTWARD TURN WILL
HAVE SOME IMPLICATION ON OVERALL PLACEMENT AS IT MOVES OUT OF THE
LEE OF THE ROCKIES. ALL LONG TERM MODELS ARE IN GENERAL AGREEMENT OF
THE INITIAL PROGRESSION TAKING THE TROUGH THROUGH NORTHERN AZ. THIS
IS THE POINT WHERE THE MODELS DIVERGE...WITH THE EMERGENCE OF THE
LEE LOW RANGING FROM NEAR DENVER TO THE OK PANHANDLE. DIFFERENCES
CONTINUE TO GROW FROM THERE ON.
THE SECOND ISSUE COMES FROM THE TIMING OF ANOTHER SHORTWAVE TROUGH
MOVING ACROSS SOUTHERN CANADA AS EACH MODEL IS HANDLING THE STRENGTH
AND TIMING DIFFERENTLY. THE NAM IS THE STRONGEST/QUICKEST WITH THE
NORTHERN TROUGH...RESULTING IN AN INTERACTION WITH THE SOUTHERN
TROUGH MUCH FARTHER WEST ACROSS MN. MEANWHILE...THE ECMWF IS MUCH
MORE OPEN WITH THE TROUGH...AND INTERACTS WITH THE SOUTHERN TROUGH
OVER WI.
FINALLY...THE NAM AND GFS ARE BOTH PRODUCING AROUND 1 INCH OF LIQUID
PRECIP ACROSS IL ON SATURDAY...WHICH COULD RESULT IN A LACK OF
MOISTURE AVAILABILITY THIS FAR NORTH.
OVERALL THINKING IS THAT THE WESTWARD TRENDS OF THE MODELS ARE
BELIEVABLE...ESPECIALLY AS THE GFS COMES INTO LINE WITH THE MORE
CONSISTENT ECMWF. THEREFORE...A BLEND OF THOSE TWO MODELS WAS USED
FOR THIS SYSTEM. THE TWO TRACK THE SFC LOW THROUGH SOUTHERN WI LATE
SATURDAY AFTERNOON...AND INTO NORTHERN LOWER MI BY SUNDAY MORNING.
EVEN THOUGH H8 TEMPS CREEP ABOVE FREEZING AHEAD OF THE SYSTEM ON
SATURDAY...DRY AIR UNDER THE DEPARTING RIDGE WILL KEEP WET BULB
TEMPS BELOW FREEZING THROUGHOUT THE COLUMN. THERMAL PROFILES SUGGEST
A VERY WET SNOWFALL FOR THE CWA...WITH RAIN MIXING IN ACROSS THE
SOUTH CENTRAL AND EAST NEAR LAKE MICHIGAN. THOUGH THERE ARE SO MANY
DISCREPANCIES AMONG THE MODELS...THERE IS FAIRLY GOOD AGREEMENT THAT
A SHIELD OF MODERATE SNOW WILL MOVE NORTHEASTWARD THROUGH THE
CWA...BEGINNING SATURDAY MORNING NEAR THE MI/WI BORDER...AND
SATURDAY AFTERNOON ALONG LAKE SUPERIOR. PINPOINTING ANY AREAS FOR
ENHANCED SNOWFALL ATTM IS QUITE DIFFICULT...BUT THERE IS A STRONG
SIGNAL OF A H8-H7 FRONTOGENESIS BAND JUST NORTH OF THE LEFT EXIT OF
THE UPPER JET...WHEREVER THOSE FEATURES END UP.
NOT LOOKING LIKE WE WILL REACH WARNING CRITERIA (6IN/12HR)
SNOWFALL...BUT SNOW COULD ACCUMULATE QUICKLY AT TIMES ON SATURDAY.
GIVEN THE WATER CONTENT OF THE SNOW...THINGS COULD GET SLOPPY ACROSS
THE CWA.
SUNDAY THROUGH WEDNESDAY...THE FORECAST BECOMES MUDDLED BY THE END
OF THE WEEKEND AS THE MID-LEVEL LOW RESPONSIBLE FOR SATURDAYS SYSTEM
BECOMES WRAPPED UP ACROSS ONTARIO. THIS WILL PUT UPPER MI IN WEAK
NORTH TO NORTHWEST FLOW THROUGH MUCH OF THE REMAINDER OF THE PERIOD.
THE MAIN RESERVOIR OF COLD AIR IS CURRENTLY WELL TO THE NORTH ACROSS
THE ARCTIC AND SIBERIA...AND NOT REALLY A MAJOR FACTOR FOR LAKE
ENHANCEMENT/LAKE EFFECT OVER THE NEXT WEEK. THE COLDEST H8 AIR
BEHIND THE SYSTEM WILL MOVE ACROSS LAKE SUPERIOR SUNDAY NIGHT. EVEN
THEN...TEMPS ARE STILL ONLY AS LOW AS -10C. ALSO...INVERSION LEVELS
ARE ONLY ABOUT 4-5KFT FOR MUCH OF THE PERIOD. THE EXPECTATION IS
THAT THERE WILL BE INTERMITTENT SNOW SHOWERS...MAINLY NEAR LAKE
SUPERIOR...INTO THE MIDDLE OF NEXT WEEK. ACCUMULATIONS WILL BE LIGHT.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)
ISSUED AT 427 PM EST WED DEC 12 2012
EXPECT VFR CONDITIONS INITIALLY AT ALL TAF SITES. A GUSTY SOUTH WIND
WILL DEVELOP LATE AFTERNOON AS THE PRES GRAD TIGHTENS AHEAD OF A NRN
PLAINS TROUGH. WILL INCLUDE LLWS AT ALL SITES TONIGHT AS A LOW-LVL
JET MAX MOVES ACROSS THE AREA. A BAND OF SNOW DEVELOPING AHEAD OF AN
APPROACHING UPPER DISTURBANCE IS FCST TO MOVE ACROSS THE KEWEENAW
PENINSULA AFT 14Z AND COULD BRING IFR CONDITIONS TO KCMX.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 427 PM EST WED DEC 12 2012
EXPECT SOUTH WINDS TO INCREASE OVER MOST OF LK SUPERIOR LATE THIS
AFTN AND ESPECIALLY TONIGHT. GUSTS TO GALES POSSIBLE EAST...BUT NOT
FREQUENT/STRONG ENOUGH TO ISSUE GALE WARNING. WINDS DIMINISH
STEADILY BLO 20 KTS LATER THURSDAY INTO THURSDAY NIGHT AS A WEAK
TROUGH CROSSES THE LAKE. WINDS STAY BLO 20 KTS THROUGH FRIDAY NIGHT
AS PRESSURE GRADIENT IS WEAK.
A LOW PRESSURE SYSTEM DEVELOPING IN THE PLAINS STILL ON TRACK TO
PUSH INTO WESTERN GREAT LAKES LATE SATURDAY INTO SUNDAY WHILE HIGH
PRESSURE MOVES ACROSS NEW ENGLAND. WINDS SHOULD INCREASE FROM THE
EAST TO 30 KTS LATE SATURDAY OVER LAKE SUPERIOR. EXACT TRACK AND
DEPTH OF SFC LOW REMAINS UNCERTAIN THOUGH SO KEPT WINDS BELOW GALE
IN THIS FORECAST.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
GALE WARNING UNTIL 7 AM EST THURSDAY FOR LMZ248-250.
&&
$$
SHORT TERM...VOSS
LONG TERM...TK
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1243 AM EST WED DEC 12 2012
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 424 PM EST TUE DEC 11 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
FROM NRN HUDSON BAY INTO THE CNTRL CONUS. WEAK SHORTWAVES MOVING
THROUGH THIS TROUGH HAVE SUPPORTED AREAS OF VERY LIGHT SNOW AND
FLURRIES TODAY. SOUTHERLY CONVERGENT FLOW OFF LAKE MICHIGAN
SUPPORTED A DOMINANT LAKE EFFECT BAND INTO LUCE COUNTY THIS MORNING
AND EARLY AFTERNOON WHICH DROPPED AT LEAST 7 INCHES OF SNOW NEAR
MCMILLAN. THIS BAND HAS SINCE WEAKENED AND MOVED EAST.
MAIN FCST CONCERN TONIGHT IS POSSIBILITY OF MODERATE LAKE EFFECT
SNOW SHOWERS OVER THE NW CWA.
TONIGHT...THE NW ONTARIO TROUGH WILL MOVE EAST AND DRAG A COLD
FRONT INTO WRN LAKE SUPERIOR. THE COLDER AIR ALONG WITH WINDS
VEERING WRLY WILL PROVIDE FAVORABLE CONDITIONS FOR LES INTO THE
KEWEENAW. WITH 850 MB TEMPS DROPPING TO AROUND -15C...INVERSION
HEIGHTS AOA 7K FT...AND LOW LEVEL CONVERGENCE STRENGTHENING DOWNWIND
FROM THE APOSTLE ISLANDS...A MODERATE TO POSSIBLE HEAVY LES BAND IS
EXPECTED TO DEVELOP. SNOWFALL AMOUNTS OF AT LEAST 2 TO 5 INCHES ARE
POSSIBLE...ESPECIALLY IN THE HIGHER TERRAIN FROM TWIN LAKES TO
CALUMET. SINCE MODELS ARE IN FAIRLY GOOD AGREEMENT THAT A HEAVIER
BAND WILL SET UP OVER THIS AREA...HAVE ELECTED TO GO WITH AN
ADVISORY FOR NORTHERN HOUGHTON COUNTY. THERE IS STILL TOO MUCH
UNCERTAINTY TO INCLUDE KEWEENAW OR ONTONAGON IN AN ADVISORY AT THIS
TIME AS IT LOOKS LIKE THEY MAY BE ON THE FRINGE OF WHERE THE HEAVIER
SNOW BAND WILL SET UP. MODEL SNDGS INDICATE SUBSIDENCE WITH QUICKLY
LOWERING INVERSION HEIGHTS AFTER MIDNIGHT SO EXPECT DIMINISHING LES
INTENSITY BY THAT TIME. COLDEST TEMPS TONIGHT SHOULD BE ALONG THE
WISCONSIN BORDER WHERE SINGLE DIGITS COULD BE REACHED UNDER LIGHT
WINDS AND CLEARING SKIES OF SFC RDG. ELSEWHERE EXPECT LOWS TO BE
GENERALLY IN THE TEENS.
WEDNESDAY...THERE COULD BE SOME LINGERING LES OVER THE KEWEENAW
EARLY IN THE DAY BUT OTHERWISE SUBSIDENCE/DRYING AND LOWERING
INVERSION ALONG WITH QUICKLY BACKING FLOW SHOULD QUICKLY END LES.
SHORTWAVE QUICKLY MOVING ACROSS THE US/CANADIAN BORDER LATE IN THE
DAY MAY BRUSH THE NW PART OF LAKE SUPERIOR WITH LIGHT SNOW/FLURRIES
BUT OTHERWISE FORCING INDICATES BETTER CHC OF SNOW WILL STAY NORTH
AND WEST OF THE CWA. INCREASING H925 WINDS TO 35-45 KTS LATE IN
THE DAY ALONG WITH NEUTRAL TO SLIGHLY UNSTABLE TEMPERATURE PROFILE
FM SFC-H9 AND INCREASING PRESSURE FALLS OVR LK SUPERIOR AND INTO
ONTARIO MAY RESULT IN AREAS NEAR LK SUPERIOR OVR NCNTRL AREAS TO
GUST AOA 30 MPH TOWARD EVENING. EXPECT HIGHS IN THE UPR 20S AND
LOWER 30S.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 424 PM EST TUE DEC 11 2012
JET STREAK WILL BE PUSHING THROUGH THE NEARLY ZONAL NORTHERN FLOW AT
THE START OF THE PERIOD. THE LEFT FRONT OF THIS 110KT STREAK WILL BE
OVER UPPER MICHIGAN AND AIDING A WEAK 1012MB SFC LOW TRACKING ALONG
THE WARM FRONT ON WEDNESDAY NIGHT. FAIRLY DRY SURFACE TO H850 LAYER
OVER MUCH OF THE LAND CWA...SO DON/T THINK THERE WOULD BE MUCH SNOW
HITTING THE SURFACE EVEN WITH THE STRONG WAA ALOFT. THUS...WILL
LIMIT THE EVENING SLIGHT CHANCES TO THE TIP OF THE KEWEENAW
PENINSULA WITH THE CHANCES OVER NORTHERN LAKE SUPERIOR. THIS FORCING
WILL SHIFT EAST DURING THE OVERNIGHT HOURS AND FOLLOW THE LOW INTO
ONTARIO.
BEFORE THE LOW DEPARTS THERE WILL BE STRONG WINDS ALOFT...ESPECIALLY
ABOVE THE INVERSION WHERE H900 WINDS APPROACH 45-50KTS ON WEDNESDAY
EVENING. BUT BELOW THE INVERSION WINDS ARE LIGHTER AND ONLY APPROACH
30-35KTS. AREA OF HIGHER PRESSURE FALLS OVER THE NORTHERN LAKE
INDICATES THE POTENTIAL FOR GUSTY WINDS ON WEDNESDAY EVENING. WITH
IT OCCURRING AT NIGHT...EXPECT THE SUSTAINED WINDS TO BE
HIGHER...BUT THE GUSTS MORE OCCASIONAL AND THE STRONGEST OVER THE
DOWNSLOPE AREAS OF THE NORTH CENTRAL. LOW LEVEL JET DIMINISHES
THROUGH THE NIGHT WITH THE LOW SHIFTING TO THE NORTHEAST AND EXPECT
THE SURFACE WINDS TO FOLLOW SUIT. THESE NIGHT TIME STRONG LOW LEVEL
JET ABOVE AN INVERSION ARE ALWAYS DIFFICULT TO DETERMINE THE AMOUNT
OF WIND THAT WILL MAKE IT TO THE SURFACE. BUFKIT MOMENTUM TRANSFER
IS USUALLY DECENT AT APPROXIMATE SUSTAINED WINDS/GUSTS...AND BOTH
NAM/GFS SOUNDINGS FOR STDM4 AND EAST BUOY ONLY SHOW A 6HR PERIOD
WEDNESDAY EVENING OF 30-35KTS. WILL LEAVE THE GALE WATCH AS
IS...SINCE HIGHER PLATFORMS WILL LIKELY SEE SOME OF THESE WINDS.
AREA WILL BE SOUTH OF THE TRAILING SURFACE TROUGH ON THURSDAY AND
EXPECT AN ABOVE NORMAL DAY OVER UPPER MICHIGAN. REMAINING
SOUTHERLY FLOW AND A FEW BREAKS IN THE MID CLOUDS SHOULD LEAD
TO ALL OF THE AREAS RISING ABOVE FREEZING DURING THE DAY.
MODELS HAVE THE IDEA OF THE TROUGH SAGGING SOUTH OVER SOUTHERN LAKE
SUPERIOR THURSDAY AFTERNOON AND REMAINING IN PLACE INTO FRIDAY
EVENING. THIS IS IN RESPONSE TO A SHORTWAVE THAT STREAKS THROUGH
THE ZONAL FLOW ON THURSDAY. AS THE TROUGH TRIES TO SAG SOUTH...LOW
LEVEL MOISTURE WILL INCREASE ON THE NORTH SIDE OF IT...BUT THERE IS
LITTLE TO NO CONVERGENCE ALONG THE TROUGH TO SUPPORT PRECIPITATION.
THUS...THE MAIN FORCING MECHANISM COMES FROM UPSLOPE FLOW. WITH THIS
SURFACE TROUGH STALLING OVER THE AREA...THE LOW LEVEL FLOW IS VERY
COMPLICATED AND UNCERTAIN AND MAKES PINPOINTING THE LIGHT
PRECIPITATION VERY DIFFICULT. SINCE THE TOP OF THE CLOUDS ARE
AROUND -8C AT 4KFT...DON/T EXPECT THERE TO BE MANY ICE CRYSTALS
IN THE CLOUDS AND REMOVE THE SNOW MENTION AND JUST GO WITH
DRIZZLE OR FREEZING DRIZZLE. LIGHT WESTERLY FLOW WOULD
FAVOR IT TO BE MAINLY OVER THE KEWEENAW ON THURSDAY AFTERNOON.
AFTER THAT...THERE ARE NO STRONG INDICATIONS ON WIND DIRECTIONS AND
WILL KEEP IT HIGHLIGHTED TO THE KEWEENAW FOR MUCH OF THE PERIOD
SINCE THEY WOULD HAVE MORE OPPORTUNITIES WITH THE VARIED WIND
DIRECTIONS. IN ADDITION...PICKED OUT A FEW LOCALIZED AREAS IN THE
NORTH CENTRAL TO HIGHLIGHT A SLIGHT CHANCE OF FREEZING
DRIZZLE BASED ON CONSENSUS WIND DIRECTIONS.
MODELS IN MUCH BETTER AGREEMENT THAN YESTERDAY HEADING INTO THE
WEEKEND...WITH THE GFS SHIFTING TOWARDS THE ECMWF/UKMET/GEM
SOLUTION. BUT...WITH THE INTERACTION OF SEVERAL DIFFERENT WAVES BY
THE TIME IT GETS HERE LEADS TO SOME UNCERTAINTY. THAT BEING
SAID...WITH THE CONSISTENCY OF THE ECMWF OVER THE LAST COUPLE DAYS
AND IT/S SUPERIOR SATELLITE BASED INITIALIZATION...WOULD WANT TO
LEAN TOWARDS THAT IDEA. WITH THE CURRENT TRACK...MUCH OF THE CWA
WILL SEE MEASURABLE...BUT LIGHT SNOW DUE TO THE BROAD AREA OF
CIRCULATION. BEST CHANCES WILL BE OVER THE SOUTHEAST HALF OF THE
CWA AND CLOSER TO THE LOW TRACK AND ALSO OVER NORTH CENTRAL UPPER
MICHIGAN WHERE UPSLOPE FLOW MAY INCREASE AMOUNTS. WITH THE ZONAL
FLOW IN PLACE AHEAD OF THIS WAVE...THERE WON/T BE MUCH COLD AIR TO
WORK WITH AND THAT LIMITS ANY LAKE ENHANCED POTENTIAL DURING THE
SYSTEM AND ALSO ON THE BACKSIDE. 12Z ECMWF HAS COME IN WITH A SLIGHT
SHIFT TO THE NORTH WITH THE LOW...SO FUTURE SHIFTS WILL HAVE TO
MONITOR IF THIS TREND CONTINUES.
FORECAST BECOMES MORE UNCERTAIN FOR MONDAY/TUESDAY OF NEXT
WEEK...WITH THE 00Z ECMWF HOLDING THE UPPER TROUGH OVER THE UPPER
GREAT LAKES REGION AND THE GFS AND IT/S ENSEMBLE PUSHING THE WAVE
OFF TO THE NEW ENGLAND STATES. 12Z ECMWF HAS TRENDED MORE
PROGRESSIVE...SO THERE COULD BE LIGHT LES OFF LAKE SUPERIOR MONDAY
AND TUESDAY AND SLIGHT CHANCE POPS REPRESENTS THAT WELL AT THIS
POINT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1236 AM EST WED DEC 12 2012
CMX...EXPECT LINGERING LES TO SHIFT TO THE N OF CMX AND DIMINISH
THRU THIS MRNG AS LARGER SCALE SUBSIDENCE DEVELOPS OVER THE AREA AND
THE FLOW BEGINS TO BACK MORE TO THE SW...WITH PREDOMINANT MVFR
CONDITIONS BY 09Z. AS THE WIND BACKS FURTHER TO THE S ON WED...VFR
WX WL BE THE RULE WITH ARRIVAL OF DRIER AIR.
IWD/SAW...PREDOMINANT MVFR CIGS AT TAF TIME WL GIVE WAY TO VFR WX BY
09Z UNDER LARGER SCALE SUBSIDENCE AND AS BACKING FLOW TO A MORE
DOWNSLOPE SW DIRECTION ADVECTS DRIER AIR INTO THE AREA. EXPECT VFR
CONDITIONS AND GUSTY S WINDS ON WED AS THE PRES GRADIENT TIGHTENS
OVER THE UPR LKS.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 424 PM EST TUE DEC 11 2012
SOUTHWEST WINDS TO 25 KTS WILL SHIFT WESTERLY THIS EVENING AS A
TROUGH MOVES THROUGH THE AREA AND THEN DIMINISH BRIEFLY BLO 20 KNOTS
LATE TONIGHT INTO WED MORNING. EXPECT INCREASING SOUTH TO SOUTHWEST
WINDS LATE WEDNESDAY INTO WEDNESDAY NIGHT. MARGINAL GALES TO 35
KNOTS ARE POSSIBLE OVER EASTERN PORTIONS OF LAKE SUPERIOR SO WILL
KEEP GALE WATCH IN EFFECT. A WEAK TROUGH DROPS ACROSS THE LAKE BY
THURSDAY EVENING. WINDS WILL DIMINISH SIGNIFICANTLY THURSDAY NIGHT
INTO FRIDAY IN THE WAKE OF THIS TROUGH. A LOW PRESSURE SYSTEM
DEVELOPING IN THE PLAINS PUSHES INTO WESTERN GREAT LAKES LATE
SATURDAY INTO SUNDAY WHILE HIGH PRESSURE MOVES ACROSS NEW ENGLAND.
WINDS SHOULD INCREASE FROM THE EAST ON SATURDAY OVER LAKE SUPERIOR.
SINCE EXACT TRACK AND DEPTH OF SFC LOW REMAINS UNCERTAIN AT THIS
TIME...WILL KEEP WINDS SUB-GALE FOR NOW.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST THIS MORNING FOR MIZ003.
LAKE SUPERIOR...
GALE WATCH FROM THIS EVENING THROUGH LATE TONIGHT FOR LSZ265>267.
LAKE MICHIGAN...
GALE WATCH FROM THIS EVENING THROUGH THURSDAY MORNING FOR LMZ248-
250.
&&
$$
SHORT TERM...VOSS
LONG TERM...SRF
AVIATION...KC
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
614 PM CST THU DEC 13 2012
.UPDATE...FOR 00Z AVIATION DISCUSSION BELOW
&&
.DISCUSSION.../ISSUED 359 PM CST THU DEC 13 2012/
MAIN WEATHER ISSUE IS OBVIOUSLY THE CHANCE FOR MIXED PCPN TOMORROW
NIGHT INTO SATURDAY NIGHT AS THE UPPER LOW CURRENTLY MOVING INTO
THE SOUTHWEST CONUS MAKES ITS WAY NORTH AND EAST INTO OUR AREA.
MODEL GUIDANCE HAS NOT CHANGED TOO DRAMATICALLY SINCE LAST
NIGHT... KEEPING THE GENERAL THEME OF DEVELOPING A SURFACE LOW IN
EASTERN COLORADO TOMORROW EVENING... THEN TAKING IT NORTHEAST
ACROSS IOWA SATURDAY MORNING... AND INTO SOUTHERN WISCONSIN BY
SATURDAY NIGHT. ALL OF THE SOLUTIONS STILL SUGGEST GOOD WARMING IN
THE BOTTOM 5K FT OR SO OF THE PROFILE AHEAD OF THE SYSTEM...
MAKING PCPN-TYPE ISSUES THE MAIN FORECAST CHALLENGE. THERE ARE
DIFFERENCES IN THE DEGREE TO WHICH THE MODELS WARM THINGS ALOFT...
AND EQUALLY IF NOT MORE IMPORTANT DIFFERENCES IN HOW THEY HANDLE
NEAR SURFACE TEMPERATURES. ALSO OF CONCERN IS EXACTLY HOW MUCH
PCPN WILL OCCUR... WITH THAT VARYING QUITE A BIT OVER THE WESTERN
PORTION OF THE CWFA... WHERE THE NAM AND ECMWF BOTH DEVELOP MORE
IN THE WAY OF MID-LEVEL DEFORMATION AND FRONTOGENESIS IN
COMPARISON TO THE GFS AND MANY OF THE SREF MEMBERS. WITH THE UPPER
WAVE JUST NOW COMING ONSHORE WE SHOULD SEE A BIT BETTER SAMPLING
OF ITS DETAILS WITH THE UPPER AIR NETWORK THIS EVENING... WHICH
MAY HAVE MORE OF AN IMPACT THAN IN SOME SITUATIONS GIVEN LIMITED
SATELLITE SAMPLING WHILE IT/S BEEN OFFSHORE DUE TO THE DRY
ATMOSPHERIC PROFILE WHICH HAS LIMITED GETTING MUCH VERTICAL
RESOLUTION SAMPLING OF THE TROUGH OVER THE PAST FEW DAYS. FOR
NOW... WILL NOT LATCH ONTO THE SPECIFICS OF ANY PARTICULAR
SOLUTION... AND INSTEAD GO IN LINE WITH MORE OF GFS/NAM/ECMWF
BLEND... LEANING SLIGHTLY MORE TOWARD THE GFS AT THIS POINT SINCE
ITS QPF SEEMS TO BETTER MATCH THE ANTICIPATED LARGE SCALE FORCING.
THE 12Z FIM IS ALSO FAIRLY SIMILAR TO THE GFS IN ITS HANDLING OF
THINGS.
FOR TONIGHT... WE WILL SEE THE WEAK SURFACE RIDGE TO OUR NORTHWEST
BUILD IN ACROSS THE AREA IN THE WAKE OF TODAY/S COLD FRONTAL
PASSAGE. THE WIDESPREAD STRATUS UPSTREAM HAS MADE LITTLE PROGRESS
SOUTHEAST TODAY... SO THE NIGHT AT LEAST LOOKS TO START OUT CLEAR
TO PARTLY CLOUDY. HOWEVER... WITH DEWPOINTS STILL IN THE 20S
ACROSS MUCH OF THE AREA... AND WITH SOME ADDITIONAL MELTING HAVING
OCCURRED AT LEAST OVER THE SOUTH AND EAST... WOULD EXPECT TO SEE
AREAS OF FOG AND SOME STRATUS TO DEVELOP IN SITU TONIGHT. WHATEVER
DEVELOPS SHOULD BE MOVED OUT RATHER QUICKLY TOMORROW AS FAIRLY
ROBUST WARM ADVECTION GETS GOING DURING THE MORNING AND EARLY
AFTERNOON AHEAD OF THE NEXT SYSTEM. THE 300K ISENTROPIC SURFACES
FROM THE NAM AND GFS HAVE DECENT WARM ADVECTION THROUGH THE
EVENING... BUT DON/T APPEAR TO LOWER CONDENSATION PRESSURE
DEFICITS ENOUGH FOR PCPN UNTIL AFTER 06Z FOR MOST OF THE AREA...
AND PARTICULARLY BY 12Z SATURDAY. AT THAT POINT... 925MB
TEMPERATURES LOOK TO BE ABOVE FREEZING OVER MOST OF THE AREA...
WITH 850MB TEMPERATURE ABOVE FREEZING OVER THE ENTIRE AREA. WE
WILL BE MOISTENING THROUGH THE DEPTH OF THE COLUMN RATHER QUICKLY
SATURDAY MORNING... SO WOULD EXPECT WHAT IS INITIALLY TO BE LIGHT
PRECIPITATION TO BECOME SOMEWHAT HEAVIER AROUND AND AFTER 12Z.
WITH TEMPERATURES ALOFT EXPECTED TO BE ABOVE FREEZING OVER THE
ENTIRE AREA... WE WILL BE LOOKING AT THE POTENTIAL FOR WIDESPREAD
SLEET AND/OR FREEZING RAIN. 2M TEMPERATURES OVER THE SOUTHERN CWFA
LOOK TO BE ABOVE ZERO AT THAT POINT... WHICH MAY ALSO BE IN THE
CASE IN THE TWIN CITIES METRO... BUT MOST OTHER LOCATIONS SHOULD
STILL BE BELOW FREEZING... WHICH COULD MAKE FOR SEVERAL HOURS OF
MESSY CONDITIONS BEFORE LOW LEVEL TEMPERATURES CLIMB ABOVE
FREEZING DUE TO CONTINUED WARM ADVECTION FROM EAST AND SOUTHEAST
FLOW. THE FAR WEST AND NORTHWEST CWFA ALSO LOOKS LIKE IT WILL HAVE
ABOVE FREEZING TEMPERATURES ALOFT SATURDAY MORNING... BUT PERHAPS
NOT QUITE AS WARM... SO THEY COULD SEE A BIT MORE IN THE WAY OF
SLEET VS FREEZING RAIN. HOWEVER... PCPN AMOUNTS IN THAT AREA MAY
BE LIMITED DEPENDING UPON WHETHER THINGS WINDS UP MORE LIKE THE
GFS/FIM OR LIKE THE NAM/ECMWF.
LARGE SCALE FORCING FOR THE SATURDAY SYSTEM LOOKS A BIT TRICKY...
SINCE IT IS NOT GOING TO BE A PHASED NORTHERN/SOUTHERN STREAM
SHORTWAVE TROUGH... BUT A SOUTHERN STREAM WAVE LIFTING NORTHEAST
INTO THE PREVAILING UPPER RIDGE. THIS WILL MAKE IT DIFFICULT FOR
IT TO ESTABLISH ANY PERSISTENT AREA OF MID-LEVEL DEFORMATION
NORTHWEST OF THE SURFACE LOW... AND MOST OF THE UPPER DIVERGENCE
ASSOCIATED WITH ITS UPPER JET WILL PUSH EAST OF OUR AREA VERY
QUICKLY ON SATURDAY. THE 850-500MB Q-VECTOR CONVERGENCE FROM THE
NAM SUGGESTS THIS AS WELL... PUSHING MOST OF THE FORCING ACROSS
OUR AREA EARLY SATURDAY MORNING... THEN SUGGESTING WEAK FORCING
AND EVEN SOME SUBSIDENCE BY LATER IN THE DAY. IT DOES HANG ONTO
SOME FORCING ACROSS THE WEST... WHERE IT ALSO INDICATES AND AREA
OF 850-700MB FRONTOGENESIS ASSOCIATED WITH THE SECONDARY PCPN AREA
IT DEPICTS. HOWEVER... FEEL IT IS TOO EARLY TO BUY INTO THAT
MESOSCALE FEATURE... PARTICULARLY WITH THE GFS... FIM... AND MANY
OF THE SREF MEMBERS NOT DOING SO. THE THALER-QG DIAGNOSTICS FOR
THE NAM... WHICH MAINLY CONSIDER THE OVERALL LARGE SCALE
FORCING... SHOW A MUCH SIMILAR PATTERN OF VERTICAL MOTION AS THE
GFS DOES... AND HAVE SIMILAR QG-INDUCED NORTHWEST-SOUTHEAST PCPN
GRADIENT AS THE FULL SOLUTION OF THE GFS. WITH WARM TEMPERATURES
ALOFT LOOKING TO LIMIT SNOWFALL POTENTIAL FOR FRIDAY NIGHT AND
MUCH OF SATURDAY... THE MAIN CONCERN BECOMES FREEZING
PRECIPITATION AS WELL AS SOME POTENTIAL FOR SLEET. IT IS LIKELY
THAT A WINTER WEATHER ADVISORY WILL BE ISSUED AT SOME POINT LATER
TONIGHT OR FRIDAY MORNING TO ACCOUNT FOR THE MIXED PCPN
POTENTIAL... BUT AT THIS POINT THE LOCATION... TIMING... AND
AMOUNTS ARE TOO UNCERTAIN TO ISSUE ANYTHING. AND... THE MAGNITUDE
IS ALSO IN QUESTION... WITH THE LOCATIONS MOST LIKELY TO SEE A
LONGER DURATION OF FZRA/IP ALSO LOOKING LIKE THEY WILL RECEIVE
LOWER AMOUNTS OF PCPN. THE PRIMARY THREAT WILL LIKELY BE WITH THE
INITIAL SURGE OF PCPN THAT LIFTS NORTHEAST THROUGH THE AREA
SATURDAY MORNING AHEAD OF THE UPPER WAVE IN THE INITIAL AREA OF
UPPER DIVERGENCE AND DPVA... MAKING THE THERMAL PROFILE AND AMOUNT
OF PCPN THAT OCCURS AT THAT TIME THE KEY ISSUES. THOSE FACTORS
SHOULD BECOME BETTER DEFINED WITH TONIGHT/S NUMERICAL GUIDANCE. AT
THIS POINT... ALL BUT THE SOUTHERN PORTION OF THE AREA SHOULD AT
LEAST PREPARE FOR A PERIOD OF SOME FREEZING RAIN AND/OR SLEET WITH
SOME ACCUMULATION OF ICE POSSIBLE FROM LATE TONIGHT INTO SATURDAY
MORNING.
SATURATION AND SOME DYNAMIC COOLING ASSOCIATED WITH THE PV ANOMALY
MOVING NEARBY SHOULD ALLOW FOR THE PROFILE TO COOL DURING THE
AFTERNOON AND INTO THE EVENING HOURS... ALLOWING PCPN TO
TRANSITION BACK TO SNOW. HOWEVER... BEFORE THAT OCCURS... THERE
CERTAINLY COULD BE A PERIOD OF LIGHT RAIN ACROSS A GOOD PART OF
THE SOUTHERN AND EASTERN PORTION OF THE AREA FROM LATE SATURDAY
MORNING INTO THE AFTERNOON. ONCE THINGS TRANSITION TO SNOW WE WILL
ALREADY BE ON THE BACKSIDE OF THE UPPER WAVE AND WITH IT QUICKLY
EJECTING NORTHEAST IT DOESN/T APPEAR WE WILL KEEP MUCH OF A
COMBINATION OF MOISTURE AND FORCING AROUND FOR LONG. SO... ANY
SNOW ACCUMULATIONS LOOK TO BE FAIRLY LIMITED AT THIS POINT...
TYPICALLY UNDER THREE INCHES. HOWEVER... SHOULD WE NOT WARM AS
MUCH AS ANTICIPATED INITIALLY... THEN SOME OF THE EARLY PCPN COULD
FALL AS SNOW AND THE TRANSITION BACK TO SNOW WOULD OCCUR SOONER...
WHICH COULD BOOST THOSE TOTAL SOME. BUT... WITH OVERALL LIQUID PCPN
EXPECTED TO RANGE FROM 0.10-0.50... IT WILL BE TOUGH FOR ANYONE TO
SEE MUCH MORE THAN 4 OR 5 INCHES EVEN IF THEY WERE SOMEHOW ABLE TO
STAY ALL SNOW. CURIOUSLY... NORTHERN PORTION OF THE WEST CENTRAL
WISCONSIN COUNTIES AND THE NORTH CENTRAL PORTION OF THE CWFA LOOK
LIKE THEY MAY SEE THE COOLEST PROFILE FOR MUCH OF THE EVENT...
MAKING THOSE AREAS THE MOST LIKELY TO SEE THE GREATER SNOW IF IT
IS A BIT COOLER THAN EXPECTED AND/OR MORE SUBSTANTIAL FZRA/IP
SHOULD WE BE ON THE WARMER END OF THINGS.
A WEAK RIDGE OF HIGH PRESSURE WILL BUILD INTO THE AREA ON
SUNDAY... WITH COOLER BUT CERTAINLY NOT COLD TEMPERATURES. NEAR TO
ABOVE NORMAL TEMPERATURES THEN LOOK TO REIGN THROUGH THE WEEK...
WITH THE NEXT CHANCE FOR MORE WIDESPREAD PCPN HOLDING OFF UNTIL
THE MIDDLE TO LATTER HALF OF THE WEEK AS ANOTHER SYSTEM DEVELOPS
IN THE LEE OF THE ROCKIES AND LIFTS NORTHEAST TOWARD THE GREAT
LAKES. THE GFS AND ECMWF ARE ACTUALLY IN DECENT AGREEMENT AT THIS
POINT... AND BOTH HAVE A TRACK WHICH WARRANTS KEEPING AN EYE ON
THINGS... SINCE WE WOULD BE UNDER OR NEAR THE PCPN SWATH
ASSOCIATED WITH IT. AT THIS POINT... THIS SYSTEM ALSO APPEARS TO
BE BETTER PHASED WITH THE NORTHERN STREAM AND RESERVOIR OF COLD
AIR TO OUR NORTH... PERHAPS MAKING PCPN-TYPE LESS OF AN ISSUE IF
AT ALL.
&&
.AVIATION.../00Z TAF ISSUANCE/
MAIN CONCERNS THIS TAF ISSUANCE ARE WHETHER STRATUS AND FOG WILL
DEVELOP AND WHAT CIGS/VSBYS WILL BE OVERNIGHT. VSBYS HAVE ALREADY
BEGUN INCHING DOWN IN CENTRAL MN THIS EVENING TO BETWEEN 5 AND
7SM. FAIRLY DENSE DECK OF CIRRUS CLOUDS WILL CONTINUE EXPANDING
FROM SOUTHERN MN ACROSS THE FORECAST AREA THIS EVENING...WHICH MAY
HELP ABATE A SHARP DROP IN VSBY TRENDS. HAVE THEREFORE INCLUDED
MODEST VSBY REDUCTIONS TO BETWEEN 3 AND 5SM. HAVE ALSO INCLUDED
SCT-BKN MVFR LEVEL CLOUDS IN ANTICIPATION OF SOME STRATUS
DEVELOPMENT...ALTHOUGH CONFIDENCE IS NOT HIGH. POTENTIAL FOR IFR
DEVELOPMENT IS ALSO STILL POSSIBLE AT KAXN AND KSTC...WHICH IS
SUPPORTED BY THE HRRR CLOUD BASE PROGS. WINDS WILL BE LIGHT AND
VARIABLE THIS EVE...AND THEN INCREASE TO AROUND 10 KTS FROM THE
SOUTHEAST ON FRIDAY MORNING. CONDITIONS WILL DETERIORATE SHORTLY
AFTER THE END OF THIS TAF PERIOD /AFTER 06Z SATURDAY/ WHEN THE
NEXT SYSTEM BRINGS A WINTRY MIX OF PRECIPITATION TO THE AREA AND
NOTABLE CIG/VSBY REDUCTIONS.
KMSP...
LOW CONFIDENCE IN WHETHER THE SITE WILL ACTUALLY SEE MVFR
CONDITIONS OVERNIGHT...BUT CURRENT THINKING IS THAT REDUCTIONS
WOULD ONLY BE TO AROUND 6SM AND THE CLOUD DECK OF A SCT NATURE
/AROUND 1500 FT/. OTHERWISE...A BKN CIRRUS DECK WILL OVERSPREAD
THE AREA DURING THE PERIOD...WITH BKN-OVC MVFR CIGS AND
POTENTIALLY FREEZING PRECIP ARRIVING AROUND/AFTER 05Z SATURDAY.
WINDS WILL BE LIGHT AND VARIABLE THROUGH THE NIGHT...AND THEN
SOUTHEASTERLY FROM 6 TO 12 KTS ON FRIDAY.
/OUTLOOK FOR KMSP/
FRI NIGHT...MVFR CONDS DEVELOPING LATE. SE WIND 5-10 KT.
SAT...IFR/MVFR CONDS LIKELY IN RA/SN/ZR...E TO NE WIND 5-10 KT.
SUN...IFR/MVFR CONDS EARLY...SLOW IMPROVEMENT DURING THE DAY. NW
WIND 5-10 KT.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
TRH/LS
AREA FORECAST DISCUSSION
NWS DULUTH MN
310 PM CST WED DEC 12 2012
.SHORT TERM.../NOW - THURSDAY NIGHT/
THE FOCUSES FOR THIS FORECAST INCLUDE CHANCES OF LIGHT SNOW
THROUGH THIS EVENING...AND AGAIN FOR LATE TONIGHT INTO THURSDAY
AFTERNOON...BOTH OF WHICH MAINLY AFFECT THE NORTHERN TIER OF NE
MINNESOTA COUNTIES.
LIGHT SNOW WILL CONTINUE TO BE POSSIBLE ACROSS PARTS OF THE FAR
NORTHERN FA...MAINLY FAR NE MINNESOTA...THROUGH THIS EVENING DUE
TO THE WARM SOUTHERLY FLOW OVER A PASSING INVERTED TROUGH.
HOWEVER...MOST OF THE SNOW WILL FALL IN ONTARIO. ADDED PATCHY FOG
TO THE FAR NORTH SHORE OF THE ARROWHEAD THROUGH EARLY THIS EVENING
DUE TO THE ONSHORE WINDS WITH LONG FETCH...BUT THE FOG SHOULD
BEGIN TO DISSIPATE LATER THIS EVENING WHEN THE WIND DIRECTION
CHANGES. AS THE INVERTED TROUGH MOVES THROUGH THE FA TONIGHT...THE
SOUTHERLY WINDS WILL SUBSIDE AND BEGIN TO BECOME NORTHERLY. CLOUD
COVER WILL HELP PROP UP OVERNIGHT TEMPERATURES WITH LOWS MAINLY IN
THE TEENS AND TWENTIES...EXCEPT FOR SINGLE DIGITS IN THE FAR NW
FA.
THE MODELS ARE IN FAIRLY GOOD AGREEMENT ABOUT A FRONTOGENETICAL
BAND OF LIGHT SNOW MOVING IN FROM NW MINNESOTA INTO NE MINNESOTA
LATE TONIGHT AND TOMORROW MORNING. THIS BAND OF LIGHT SNOW NORTH
OF THE STATIONARY FRONT COULD LINGER INTO THURSDAY AFTERNOON. MOST
AFFECTED AREAS ACROSS NE MINNESOTA WILL PROBABLY GET AT LEAST A
COUPLE TENTHS OF AN INCH...BUT WOULD NOT BE SURPRISED BY IF SOME
AREAS GET AROUND AN INCH. EXPECT A CLOUDY DAY...EXCEPT IN PARTS OF
THE FAR SE FA WHERE THERE SHOULD BE SOME PEAKS OF SUNSHINE. HIGH
TEMPERATURES SHOULD RANGE FROM THE LOW 30S ACROSS THE SE FA TO THE
TEENS IN THE NW FA.
HIGH PRESSURE WILL MOVE INTO THE NORTHLAND THURSDAY NIGHT...SO
BESIDES SOME POSSIBLE LINGERING LIGHT SNOW OVER THE
ARROWHEAD...THE REST OF THE FA SHOULD BE DRY. THE PARTLY TO MOSTLY
CLOUDY SKIES WILL HELP PROP UP TEMPERATURES. OVERNIGHT LOWS WILL
RANGE FROM THE UPPER TEENS IN THE SE FA TO THE LOWER SINGLE DIGITS
IN THE NW FA.
.LONG TERM.../FRIDAY - WEDNESDAY/
FOCUS DURING THIS PERIOD WILL BE ON A SYSTEM BRINGING
PRECIPITATION TO THE NORTHLAND THIS WEEKEND...POSSIBLY A MIX
FRIDAY NIGHT INTO SATURDAY MORNING. THE MODELS ARE IN PRETTY GOOD
AGREEMENT WITH THE SYSTEM THIS WEEKEND...AND A BLEND OF THE GFS
AND ECMWF WAS USED FOR MOST OF THE FORECAST DETAILS. THE NAM IS
FURTHER NORTH WITH THE TRACK...AND IS WARMER IN THE LOW LEVELS AS
A RESULT.
THE UPPER LEVEL SYSTEM OF CONCERN THIS WEEKEND WILL START OVER THE
CA/AZ/MEXICO AREA FRIDAY MORNING...THEN MOVE NORTHEAST TOWARD
THE NORTHLAND. FRIDAY WILL BE DRY OVER THE REGION. WARM AIR
ADVECTION AND THE APPROACHING UPPER TROUGH MAY BE ENOUGH TO CAUSE
SOME LIGHT PRECIPITATION LATE FRIDAY NIGHT...MAINLY OVER THE
SOUTHERN HALF OF THE CWA. PRECIPITATION TYPE IS IN QUESTION...AS
THE MODELS DO SHOW A WARM NOSE WHICH COULD CAUSE A WINTRY MIX OF
SNOW/FREEZING RAIN OR SLEET FRIDAY NIGHT/SATURDAY MORNING OVER
SOUTHERN AREAS. SEVERAL OF THE MODELS HAVE TRENDED A BIT FURTHER
NORTH WITH THIS SYSTEM WHICH DOES TWO THINGS 1) BRINGS A BETTER
CHANCE FOR PRECIPITATION INTO THE NORTHLAND AND 2) BRINGS IN
WARMER LOW LEVEL TEMPERATURES COMPLICATING THE PRECIPITATION TYPE
FORECAST. AS THE UPPER TROUGH AND SURFACE LOW MOVE OVER WISCONSIN
SATURDAY...PRECIPITATION SHOULD BECOME MORE WIDESPREAD AND BOTH
THE GFS AND ECMWF SUGGEST MAINLY SNOW WILL FALL DURING THE DAY
SATURDAY. AT THIS POINT...IT APPEARS SEVERAL INCHES OF SNOW WILL
BE POSSIBLE BY LATE SATURDAY EVENING...WITH THE BEST CHANCE
OCCURRING OVER NORTHWEST WISCONSIN. THE STRONGEST FORCING LOOKS TO
REMAIN SOUTH OF THE NORTHLAND...AND AT THIS POINT THERE DOES NOT
LOOK TO BE A SIGNIFICANT CONTRIBUTION OF LIFT FROM FGEN. WARMER
TEMPERATURES AT 850MB ALSO MEANS ANY LAKE CONTRIBUTION WILL BE
QUITE LIMITED. IT`S JUST TOO EARLY TO FORECAST SPECIFIC SNOW
AMOUNTS...AND DETAILS WILL BE ADDED LATER. THOSE WITH TRAVEL PLANS
OVER THE WEEKEND SHOULD MONITOR LATER FORECASTS AND STATEMENTS. WE
EXPECT HIGHS SATURDAY NEAR 30 OVER THE FAR NORTH...AND THE LOWER
THIRTIES OVER NORTHWEST WISCONSIN.
THE REST OF THE EXTENDED PERIOD LOOKS RELATIVELY QUIET AND WE HAVE
PERIODIC CHANCES FOR LIGHT SNOW. TEMPERATURES SHOULD BE SEVERAL
DEGREES ABOVE NORMAL THIS WEEKEND...THEN COOL TO NORMAL BY TUESDAY
INTO WEDNESDAY.
&&
.AVIATION.../18Z TAF ISSUANCE/
MAINLY VFR CONDITIONS COVERED THE NORTHLAND AS OF LATE
MORNING...WITH SOME LOWER CEILINGS AND SOME LIGHT SNOW ALONG THE
NORTH SHORE DUE TO ONSHORE WINDS THERE. WAA CONTINUED OVER THE
NORTHLAND...AND STILL MAY LEAD TO SOME LIGHT SNOW AND LOWERING
CEILINGS OVER THE FAR NORTH THIS AFTERNOON. WE DID DELAY THE LOWER
CEILINGS...AND REMOVED THE MENTION FROM KDLH. KDLH WAS
EXPERIENCING A SCATTERED DECK AS LOW AS 400FT THIS MORNING...BUT
AS TEMPS WARM THIS AFTERNOON...LAKE GENERATED CLOUDS SHOULD BECOME
MORE SCARCE. THE RAP AND NAM BOTH SUGGEST LOWER CEILINGS WILL
DEVELOP OVER THE NORTH...MAINLY AFFECTING KINL.
TONIGHT...WE COULD SEE SOME FOG IN SPOTS. A WEAK WAVE WILL MOVE
THROUGH THE AREA AS WELL...AND WITH THIS THERMAL GRADIENT IN
PLACE...SOME LIGHT SNOW WILL BE POSSIBLE. WE ADDED THE MENTION TO
ALL TAFS EXCEPT KHYR. SOME LOWER CEILINGS...WILL ALSO BECOME MORE
LIKELY AS THE NIGHT PROGRESSES. WINDS WILL TURN TO THE NORTH TO
NORTHEAST LATE TONIGHT INTO THURSDAY MORNING.
&&
.POINT TEMPS/POPS...
DLH 20 30 15 28 / 20 20 10 10
INL 7 17 4 21 / 10 10 10 10
BRD 17 27 11 28 / 20 10 10 10
HYR 22 34 16 33 / 0 0 0 10
ASX 25 34 21 32 / 0 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 4 AM CST THURSDAY
FOR LSZ140-141.
&&
$$
SHORT TERM...GROCHOCINSKI
LONG TERM....MELDE
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS DULUTH MN
1143 AM CST WED DEC 12 2012
.AVIATION...18Z TAFS
MAINLY VFR CONDITIONS COVERED THE NORTHLAND AS OF LATE
MORNING...WITH SOME LOWER CEILINGS AND SOME LIGHT SNOW ALONG THE
NORTH SHORE DUE TO ONSHORE WINDS THERE. WAA CONTINUED OVER THE
NORTHLAND...AND STILL MAY LEAD TO SOME LIGHT SNOW AND LOWERING
CEILINGS OVER THE FAR NORTH THIS AFTERNOON. WE DID DELAY THE LOWER
CEILINGS...AND REMOVED THE MENTION FROM KDLH. KDLH WAS
EXPERIENCING A SCATTERED DECK AS LOW AS 400FT THIS MORNING...BUT AS
TEMPS WARM THIS AFTERNOON...LAKE GENERATED CLOUDS SHOULD BECOME
MORE SCARCE. THE RAP AND NAM BOTH SUGGEST LOWER CEILINGS WILL
DEVELOP OVER THE NORTH...MAINLY AFFECTING KINL.
TONIGHT...WE COULD SEE SOME FOG IN SPOTS. A WEAK WAVE WILL MOVE
THROUGH THE AREA AS WELL...AND WITH THIS THERMAL GRADIENT IN
PLACE...SOME LIGHT SNOW WILL BE POSSIBLE. WE ADDED THE MENTION TO
ALL TAFS EXCEPT KHYR. SOME LOWER CEILINGS...WILL ALSO BECOME MORE
LIKELY AS THE NIGHT PROGRESSES. WINDS WILL TURN TO THE NORTH TO
NORTHEAST LATE TONIGHT INTO THURSDAY MORNING.
&&
.PREV DISCUSSION... /ISSUED 937 AM CST WED DEC 12 2012/
UPDATE...
MADE SOME UPDATES TO POPS AND WEATHER THROUGH TONIGHT TO BETTER
REFLECT THE BAND OF LIGHT SNOW IN NORTHWESTERN MINNESOTA AND NORTH
OF THE CANADIAN BORDER THAT WILL SLIDE EAST TODAY AND TONIGHT.
STILL THINK THIS WILL MAINLY AFFECT THE FAR NORTHERN FA WHERE SOME
AREAS MAY GET SEVERAL TENTHS OF AN INCH OF SNOW. OTHERWISE...THE
FORECAST LOOKS ON TRACK.
PREV DISCUSSION... /ISSUED 622 AM CST WED DEC 12 2012/
AVIATION.../12Z TAF ISSUANCE/
WIDESPREAD VFR CONDITIONS WILL BE FOUND ACROSS THE AREA THROUGHOUT
THE TAF PERIOD...BUT THERE SHOULD ALSO BE SOME BATCHES OF LOWER
CLOUDS DEVELOPING THROUGHOUT THE PERIOD AS WELL. SOME MVFR CIGS
AND EVEN SOME MVFR VSBYS...ESPECIALLY IN THE NORTH...WILL BE
POSSIBLE.
PREV DISCUSSION... /ISSUED 352 AM CST WED DEC 12 2012/
SHORT TERM...
TODAY THROUGH THURSDAY AFTERNOON...
MAIN SHORT TERM CONCERNS REMAIN FOCUSED AROUND THE POTENTIAL FOR
SNOW SHOWERS THIS AFTERNOON...AND AGAIN LATE TONIGHT/EARLY
THURSDAY...BOTH TIMES ACROSS THE NRN TIER COUNTIES OF NE MN. ONLY
LIGHT ACCUMULATIONS ARE EXPECTED.
BROAD CYCLONIC FLOW CONTINUES ACROSS MUCH OF THE CONUS WITH A
SHARP 500MB TROUGH DROPPING SWD THROUGH THE PAC NW AND INTO THE
NRN ROCKIES...ALONG WITH A WEAK EMBEDDED S/W AND DEVELOPING SFC
INVERTED TROUGH MOVING INTO THE WRN DAKOTAS EARLY THIS MORNING.
THIS SURFACE TROUGH WILL CONTINUE TO MOVE EWD INTO WRN MN THIS
MORNING AND AT THE SAME TIME DRAW UP SLIGHTLY WARMER AIR FROM THE
SOUTH AS SFC WINDS SHIFT TO THE S/SW. THIS SYSTEM WILL HAVE WEAK-
MDT UPPER LEVEL SUPPORT AS A 90KT JET TRANSLATES EWD THROUGH THE
NRN PLAINS/UPPER MIDWEST...AND AREAS OF NE MN REMAIN IN THE LEFT
EXIT REGION OF THE JET. IT APPEARS THERE WILL ALSO BE A FAVORABLE
AREA OF 925-850MB F-GEN ALONG THE LEADING EDGE OF THIS SFC TROUGH.
THIS WILL BE A FAIRLY QUICK MOVING SYSTEM...AND ONLY DROP AN INCH
OR SO OF SNOW FROM INL TO ELO TO GNA...WITH LIGHTER AMTS FURTHER
SOUTH.
A SECONDARY JET MAX WILL EJECT NEWD OUT OF THE SWRN U.S. TONIGHT
ALONG WITH ANOTHER S/W FROM THE NRN PLAINS. THESE TWO FEATURES
WILL COMBINE WITH THE SLOW-MOVING STATIONARY SFC TROUGH LINGERING
OVER THE NORTHLAND AND PRODUCE ANOTHER ROUND OF SNOW SHOWERS. THIS
SYSTEM IS EXPECTED TO BE FAST-MOVING AS WELL...AND DROP ANOTHER
INCH OR SO OF SNOW SLIGHTLY FURTHER SOUTH. COULD SEE THE MOST
SNOW...AROUND 1-2 INCHES...WITHIN AN AREA FROM PARK FALLS TO HIBBING
TO LUTSEN. MOST OF THE SNOW SHOWERS SHOULD END BY LATE THUR
AFTERNOON.
TEMPERATURE THROUGH THE SHORT TERM WILL BE SLIGHTLY MORE MILD THAN
THE PAST COUPLE DAYS WITH HIGHS IN THE 20S AND LOWER 30S AND
OVERNIGHT LOWS IN THE TEENS.
LONG TERM...
THURSDAY NIGHT THROUGH WEDNESDAY...
THIS TIME PERIOD IS SHAPING UP TO BE A POTENTIALLY ACTIVE PERIOD
ONCE AGAIN...AS WE FOCUS ON THE POTENTIAL SNOWFALL FOR THE
WEEKEND. THE GFS AND GEM PARTICULARLY ARE NOTING SOME
PRECIPITATION LINGERING IN THE MN ARROWHEAD FOR THURSDAY
EVENING...ESPECIALLY FOR COASTAL AREAS BEHIND A DEPARTING FRONTAL
BOUNDARY AND UPPER LEVEL SHORTWAVE. FRIDAY WILL GENERALLY BE
QUIET...WITH WAA INITIATING AHEAD OF A DEEP SW TROUGH. THE GEM IS
HINTING AT SOME LIGHT PRECIPITATION ACROSS THE CWA ON FRIDAY...AND
CANNOT RULE IT OUT BUT WILL LEAVE IT DRY AT THIS TIME.
ACCUMULATING SNOWFALL AND POSSIBLY SOME LIGHT FREEZING RAIN OR
DRIZZLE WILL BE THE MAIN STORY FOR SATURDAY INTO SUNDAY. THE GFS
GENERALLY KEEPS THE PRECIPITATION SOUTH AND EAST OF THE CWA...BUT
THE NAM...GEM AND ECMWF ALL BRING A FAIRLY LARGE AREA OF QPF
ACROSS THE CWA WITH THE POTENTIAL FOR SEVERAL INCHES OF
ACCUMULATION. THE SYSTEM LOOKS TO BE FAIRLY WARM...SO THERE COULD
BE SOME LIGHT FREEZING RAIN OR DRIZZLE AS WELL. WILL NEED TO KEEP
A CLOSE EYE ON THIS SYSTEM AS IT HAS THE POTENTIAL TO COMPLICATE
WEEKEND TRAVEL. AFTER THIS WEEKEND...IT LOOKS FAIRLY QUIET AGAIN
INTO MIDWEEK. HIGH TEMPERATURES WILL GENERALLY BE IN THE 20S AND
30S THROUGHOUT THE EXTENDED TIME PERIOD WITH LOWS RANGING FROM THE
TEENS TO AROUND 30.
&&
.POINT TEMPS/POPS...
DLH 27 20 29 15 / 0 20 10 10
INL 20 8 15 5 / 60 10 20 10
BRD 29 18 26 12 / 0 20 10 0
HYR 33 22 32 17 / 0 0 10 10
ASX 33 25 34 22 / 0 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
SHORT TERM...GROCHOCINSKI
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS DULUTH MN
1148 PM CST TUE DEC 11 2012
.AVIATION.../06Z TAF ISSUANCE/
LOW CLOUDS ACROSS NWRN WI AND THE MN ARROWHEAD WILL CONTINUE TO
MOVE OFF TO THE EAST EARLY THIS MORNING AS A RIDGE OF HIGH
PRESSURE BUILDS OVER THE UPPER MIDWEST. THIS RIDGE WILL QUICKLY
DEPART EWD AND GIVE WAY TO A SHORTWAVE TRACKING ALONG THE INTL
BORDER. A MID-LEVEL CLOUD DECK WILL PRECEDE THE SHORTWAVE...WITH
CIGS GRADUALLY LOWERING THIS MORNING. THE SHORTWAVE WILL ALSO
PRODUCE AREAS OF LIGHT TO MODERATE SNOW WITH MVFR CIGS AND
MVFR/IFR VSBYS MAINLY NORTH OF THE IRON RANGE ON WEDNESDAY.
FARTHER SOUTH...ANY SNOW SHOULD BE IN THE FORM OF FLURRIES DUE TO
A DRY LAYER IN THE LOWER ATMOSPHERE. HAVE MENTIONED A SCT-BKN015
DECK AT MOST OF THE TAF SITE AS THE NAM12 TIME/HEIGHT CROSS
SECTIONS SHOWS A THIN LAYER OF HIGH RH NEAR THE GROUND. THIS MIGHT
BE A PRODUCT OF COLD AIR NEAR THE SURFACE...BUT NOT CONFIDENT
ENOUGH TO LEAVE MENTION OF LOW CLOUD DECK OUT OF TAFS.
&&
.PREV DISCUSSION... /ISSUED 634 PM CST TUE DEC 11 2012/
AVIATION.../00Z TAF ISSUANCE/
AN AREA OF LOW CLOUDS WITH MVFR CLOUDS ASSOC WITH A DEPARTING
SHORTWAVE WILL GRADUALLY DIMINISH OR DISSIPATE OVERNIGHT TONIGHT.
LIGHT SNOW WITH LOCALIZED MVFR CIGS WILL LINGER ACROSS THE CWA THIS
EVENING AS WELL. ANOTHER SHORTWAVE FROM CANADA WILL DIG SEWD
ACROSS THE NORTHLAND LATE TONIGHT THROUGH WEDNESDAY. LIGHT TO
MODERATE SNOW WILL AFFECT AREAS ALONG THE CANADIAN BORDER...BUT
FROM THE IRON RANGE ON SOUTH...CONDITIONS SHOULD BE MAINLY DRY.
PREV DISCUSSION... /ISSUED 314 PM CST TUE DEC 11 2012/
SHORT TERM...THROUGH WEDNESDAY NIGHT.
LAKE EFFECT SNOW ALONG THE NORTH SHORE HAS DIMINISHED THIS
AFTERNOON AS WINDS HAVE TURNED MORE WESTERLY BEHIND THE DEPARTING
LOW. A LAKE BAND OF LIGHT SNOW SHOWERS ALSO EXTENDED FROM JUST OFF
SHORE OF DOUGLAS COUNTY...ALONG THE BAYFIELD PENINSULA TOWARD RED
CLIFF. THIS WILL LIKELY CONTINUE THROUGH MOST OF THE EVENING AS
THE LOW LEVEL FLOW REMAINS WEST-SOUTHWEST. FETCH WILL BE
LIMITED...AND THE NAM AND RUC BOTH SHOW LOWERING RH THROUGH THE
EVENING...SO WE THINK ACCUMULATIONS WILL BE LIMITED. PLENTY OF CLOUDS
REMAIN OVER THE REST OF THE NORTHLAND...WITH FLURRIES/LIGHT SNOW
STILL OCCURRING. A WEAK SHORTWAVE WAS MOVING THROUGH CENTRAL
MINNESOTA THIS AFTERNOON...WITH RADAR HIGHER RETURNS WELL SOUTH OF
THE CWA.
HIGH PRESSURE WILL MOVE QUICKLY THROUGH THE NORTHLAND
TONIGHT...WITH WAA INCREASING OVERNIGHT AHEAD OF AN AREA OF LOW
PRESSURE. WE HAVE A CHANCE FOR LIGHT SNOW LATER TONIGHT OVER
NORTHWEST AREAS...AND INCREASED POPS TO LIKELY BETWEEN 09-12Z OVER
KOOCHICHING COUNTY. THE WAA AND WEAK SHORT WAVE WILL CONTINUE TO
IMPACT FAR NORTHERN AREAS WEDNESDAY...AND WE HAVE INCREASED POPS
TO LIKELY AS ACCUMULATIONS UP TO TWO INCHES WILL BE POSSIBLE IN
SPOTS. THERE MAY ALSO BE A NARROW WINDOW FOR LAKE EFFECT SNOW
WEDNESDAY MORNING BETWEEN LITTLE MARAIS AND GRAND PORTAGE AGAIN.
FETCH BECOMES FAVORABLE WEDNESDAY MORNING...BUT WAA WILL CAUSE
850MB TEMPS TO RISE QUICKLY. WE`LL HAVE TO KEEP A CLOSE EYE ON
THAT AREA AS WE COULD GET A QUICK BURST OF SEVERAL INCHES OF SNOW
IF THE TEMPS ALOFT DON`T WARM AS FAST AS ANTICIPATED.
TEMPERATURES TONIGHT WILL BE A CHALLENGE...AS THEY WILL BE HIGHLY
DEPENDENT ON CLEARING. WE DID DROP THEM MOST AREAS...HAVE SOME
WELL BELOW ZERO OVER NORTHEAST MINNESOTA. EVENING SHIFT WILL HAVE
TO MONITOR CLOUD TRENDS CLOSELY...AS WE MAY NOT BE COLD ENOUGH IF
IT CLEARS LONGER THAN ANTICIPATED. HIGHS WEDNESDAY WILL BE WARMER
THAN TODAY...WITH SOME AREAS REACHING AROUND THIRTY OVER NORTHWEST
WISCONSIN.
CONFIDENCE WEDNESDAY NIGHT IS LOWER THAN AVERAGE REGARDING SNOW
POTENTIAL. NAM WAS SHOWING A WEAK CIRCULATION AT 850MB AND
FORECASTS SOME LIGHT SNOW OVER THE FAR NORTH. THE MODELS ARE NOT
IN VERY GOOD AGREEMENT DURING THIS PERIOD. WE KEPT A MENTION OF
LIGHT SNOW OVER THE NORTH...AND EXPANDED A BIT SOUTH OVER OUR
WESTERN COUNTIES. IF THE MODELS TREND TOWARD THE NAM...WE WILL
NEED HIGHER POPS FOR SOME LIGHT SNOW ACCUMULATIONS OVER THE WEST
AND NORTHERN CWA.
LONG TERM...THURSDAY - MONDAY.
THE NORTHLAND SHOULD FIND ITSELF THURSDAY MORNING WITH A STATIONARY
FRONT NEAR OR SOUTH OF THE FA. THERE MAY BE SOME LIGHT SNOW ACROSS
THE NORTHERN FA THURSDAY ASSOCIATED WITH PLENTIFUL LOW CLOUDS NORTH
OF THE FRONT. HIGH PRESSURE IN CANADA WILL BEGIN TO EXERT GREATER
INFLUENCE ON THE NORTHLAND THURSDAY NIGHT...PROVIDING DRY WEATHER
THROUGH FRIDAY NIGHT. THE MODELS ARE LATCHING ONTO A STRONG LOW
PRESSURE SYSTEM MOVING FROM THE CENTRAL PLAINS TO UPPER MIDWEST ON
SATURDAY. THIS SYSTEM COULD BRING SIGNIFICANT SNOWFALL TO PARTS OF
THE FA...ESPECIALLY THE SOUTHEASTERN FA WHICH WILL BE IN BETTER
PROXIMITY TO THE SYSTEM. TEMPERATURES THROUGH THE PERIOD SHOULD BE
NEAR OR SLIGHTLY ABOVE NORMAL.
AVIATION...18Z TAFS
IFR/MVFR CONDITIONS ACROSS NE MINNESOTA AND NW MINNESOTA ARE
EXPECTED TO CONTINUE THROUGH THIS AFTERNOON AND INTO EARLY THIS
EVENING. CIGS WILL LIKELY RANGE FROM 1500 TO 3000 FT...AND THE
-SN WILL OCCASIONALLY REDUCE VIS TO IFR. THE SNOW SHOULD BEGIN TO
SUBSIDE LATER THIS AFTERNOON. THE CLOUDS WILL BEGIN TO CLEAR AT
KINL BY MID AFTERNOON...AND THEN AT OTHER TERMINALS LATE THIS
AFTERNOON AND EARLY THIS EVENING. EXPECT THE 5 TO 10 KNOT W TO SW
WINDS TO BECOME S TO SE TONIGHT. KINL COULD SEE MVFR CIGS
REDEVELOP LATE TONIGHT AND TOMORROW MORNING...BUT VFR CONDITIONS
ARE LIKELY TO RETURN TO KDLH/KHIB/KBRD/KHYR TONIGHT.
&&
.POINT TEMPS/POPS...
DLH 3 28 20 29 / 10 10 10 20
INL -9 23 8 19 / 60 60 30 20
BRD -5 29 17 28 / 10 10 20 10
HYR 2 32 22 33 / 20 10 10 0
ASX 5 33 25 35 / 20 10 10 10
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...NONE.
&&
$$
AVIATION...BERDES
AREA FORECAST DISCUSSION
NWS BILLINGS MT
319 PM MST WED DEC 12 2012
.SHORT TERM...VALID FOR THU AND FRI...
A CHALLENGING FORECAST DEALING WITH POTENTIAL LINGERING SNOW THIS
EVENING WILL EASE INTO A QUIET AND SEASONABLY COOL PERIOD FOR THE
END OF THE WEEK BENEATH SPLIT FLOW ALOFT.
TONIGHT...EXTRAPOLATING THE DISTINCT DRYING OBSERVED ON AFTERNOON
MOISTURE CHANNEL IMAGES IN ID AND SOUTHWESTERN MT SUGGESTS AN END
TO PRECIPITATION AT LIVINGSTON BY 00 UTC...AND AROUND BILLINGS BY
ABOUT 03 UTC. OF COURSE...THE LEADING EDGE OF THAT DRYING IS TIED
TO A STEEPENING OF MID-LEVEL LAPSE RATES...SO UPSTREAM SNOW RATES
HAVE ACTUALLY INTENSIFIED FOR A SHORT TIME JUST AHEAD OF IT. WITH
THAT IN MIND...WE KEPT LIKELY POPS IN PLACE EVEN AT BILLINGS THIS
EVENING...EVEN THOUGH THE MAIN BAND OF MOISTURE UP THROUGH 22 UTC
HAS BEEN NORTH OF THE CITY. THE SHIELD OF PRECIPITATION WHICH HAS
BEEN GOING ON NORTH AND EVEN NORTHEAST OF BILLINGS TODAY SEEMS TO
BE DRIVEN BY SOME WEAK FRONTOGENESIS...BUT THE BETTER FORCING HAS
BEEN OBSERVED ON ISENTROPIC SURFACES...WITH PRESSURE ADVECTION AT
THE 290 K LEVEL SIGNIFICANT FROM ROUNDUP TO FORSYTH. THIS FORCING
ON ISENTROPIC SURFACES EVEN DIMINISHES TOWARD 00 UTC...BUT WE DID
LEAVE IN LIKELY POPS ROUGHLY ALONG AND NORTH OF INTERSTATE 94 FOR
THE EVENING BASED ON RECENT RADAR TRENDS...THE LAST FEW HRRR RUNS
AND THE 12 UTC GFS...WHICH HAS SIMULATED THIS MOISTURE WELL. SOME
ROADS COULD BE SLICK...MUCH LIKE HAS BEEN SEEN TODAY IN THE SPOTS
THAT HAVE RECEIVED SNOW INSTEAD OF A MIX OF RAIN AND SNOW...WHICH
IS WHY WE WILL CONTINUE MENTIONING SOME TRAVEL IMPACTS OVER PARTS
OF THE AREA INTO THE EVENING. WE DO NOT ANTICIPATE ENOUGH SNOW TO
NECESSITATE A WINTER WEATHER ADVISORY ANYWHERE...BUT WE WILL NEED
TO KEEP A CLOSE EYE ON THAT POTENTIAL THIS EVENING.
BEYOND MIDNIGHT...WE EXPECT MOST AREAS TO BE DRY...MUCH LIKE MOST
12 UTC GUIDANCE SUGGESTS. WE LINGERED SOME 20 AND 30 PERCENT POPS
IN SOUTHEASTERN MT THOUGH. THE 12 UTC MET GUIDANCE SUGGESTS THERE
MAY BE SOME FOG WHERE PRECIPITATION FELL TODAY...AND BUFKIT-BASED
SOUNDING TOOLS ALSO SUPPORT THAT RISK. THUS...PATCHY FOG IS SHOWN
IN THE FORECAST AFTER 06 UTC FOR HARLOWTON...ROUNDUP...MILES CITY
AND EVEN BAKER. IF A TENTH OF AN INCH OF MOISTURE OR MORE HAPPENS
TO FALL IN BILLINGS THIS EVENING...THEN WE WILL NEED TO GIVE SOME
CONSIDERATION TO ADDING FOG TO THE FORECAST THERE TOO.
THU...WEAK LOW- AND MID-LEVEL WARM AIR ADVECTION WILL OCCUR...BUT
FORECAST SOUNDINGS SUGGEST BOUNDARY LAYER MIXING WILL BE SEVERELY
LIMITED BENEATH SPLIT FLOW ALOFT. THIS ENVIRONMENT WILL FAVOR THE
PERSISTENCE OF ANY FOG THAT FORMS TONIGHT INTO THU MORNING...WITH
SOME POTENTIAL FOR STRATUS TO LINGER OVER SOUTHEASTERN MT ALL DAY
LIKE THE 12 UTC MET MOS SUGGESTS AT MILES CITY AND BAKER. WE KEPT
HIGHS IN THOSE SPOTS COOLER THAN THE 12 UTC BIAS-CORRECTED FLAVOR
OF THE MULTI-MODEL CONSENSUS IN RESPECT TO THAT POTENTIAL...WHILE
INCREASING HIGHS SLIGHTLY IN PLACES LIKE BILLINGS IN ORDER TO TAG
ALONG WITH THAT GUIDANCE WHERE SUNSHINE IS EXPECTED. FINALLY...WE
MAINTAINED CONTINUITY IN SHOWING SOME SLIGHT CHANCE POPS UNTIL 18
UTC OVER SOUTHEASTERN MT AHEAD OF THE AXIS OF THE NORTHERN STREAM
500-HPA TROUGH...BUT CONFIDENCE IN PRECIPITATION IS VERY LOW.
FRI...LOW-LEVEL FLOW WILL BECOME MORE SOUTHWESTERLY IN ADVANCE OF
A MODEST SURFACE COLD FRONT THAT THE 12 UTC GFS...NAM...AND ECMWF
ALL SWING THROUGH THE AREA FRI EVENING. THIS SCENARIO SHOULD HELP
ADD A FEW MORE DEGREES F TO HIGHS OVER THOSE EXPECTED THU...WHICH
IS WHAT THE 12 UTC BIAS-CORRECTED MULTI-MODEL CONSENSUS PICKED UP
ON AS WELL. THE FRONTAL PASSAGE TIED TO A WEAK 500-HPA SHORT WAVE
IN THE NORTHERN STREAM OF THE WESTERLIES LOOKS DRY. HOWEVER...ONE
AREA WHERE WE MAY NEED TO CONSIDER SOME LOW POPS DOWN THE ROAD IS
ALONG THE FOOTHILLS BY LATE FRI NIGHT AS WEAK UPSLOPE DEVELOPS AS
A SURFACE HIGH DROPS INTO CENTRAL AND EASTERN MT. THERE WAS A BIT
OF A SIGNAL IN THE 12 UTC GFS FOR THAT...BUT NOT ENOUGH FOR US TO
PUT LOWER-ELEVATION POPS IN THE FORECAST YET. THE 09 UTC SREF WAS
MORE AGGRESSIVE WITH SOME LIGHT PRECIPITATION IN SOUTH CENTRAL MT
LATE FRI NIGHT...BUT IT IS ALSO AN OUTLIER SOLUTION. SCHULTZ
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
DRY CONDITIONS WILL PREVAIL FOR MOST LOCATIONS ON SATURDAY. AN
UPPER-LEVEL TROUGH WILL DIVE SOUTH ACROSS THE REGION DURING THIS
TIME. THE STRONGEST FORCING SHOULD TRACK SOUTH OF THE CWA. THE
FIRST IN A SERIES OF DISTURBANCES WILL MOVE ACROSS THE CWA ON
SUNDAY. BROAD-BRUSHED LOW POPS DURING THIS TIME. A SECOND WAVE
WILL TRACK ACROSS THE CWA ON MONDAY. AGAIN...KEPT POPS LOW AND
BROAD-BRUSHED. TUESDAY WILL GENERALLY BE DRY. A THIRD WAVE WILL
IMPACT THE CWA TUESDAY NIGHT INTO WEDNESDAY. BLENDED MAX/MIN
TEMPERATURES WITH THE BEST-PERFORMING 12Z GUIDANCE...ALLBLEND /
MOSGUIDE. TEMPERATURES WILL GENERALLY BE SEASONAL THROUGHOUT THE
PERIOD. BRS
&&
.AVIATION...
PRECIPITATION WILL CONTINUE OVER THE MOUNTAINS THROUGHOUT THE TAF
PERIOD. PRECIPITATION WILL CONTINUE OVER THE PLAINS THROUGH
TONIGHT. EXPECT BRIEF MVFR/IFR CONDITIONS. PRECIPITATION WILL
DIMINISH OVERNIGHT. PATCHY FOG WILL BE POSSIBLE EARLY THURSDAY
MORNING. VFR CONDITIONS WILL PREVAIL ON THURSDAY. BRS
&&
.PRELIMINARY POINT TEMP/POPS...
THU FRI SAT SUN MON TUE WED
-----------------------------------------------------------
BIL 023/040 021/041 020/037 019/038 021/036 024/040 021/035
61/B 01/U 11/B 02/J 22/J 11/B 22/J
LVM 022/037 019/040 018/033 024/035 019/033 026/036 020/034
41/B 01/B 11/B 12/W 22/J 11/N 22/J
HDN 023/038 017/039 016/035 015/037 019/037 019/040 018/036
51/B 00/B 11/B 01/B 22/J 11/B 22/J
MLS 021/033 016/035 018/032 015/035 018/036 019/036 020/035
72/J 00/B 00/B 01/B 12/J 11/B 22/J
4BQ 019/036 017/037 017/034 015/036 017/036 018/036 018/037
22/J 00/B 00/B 01/U 12/J 11/B 22/J
BHK 019/031 013/036 016/031 015/033 016/033 017/035 018/036
52/J 00/B 00/B 01/B 12/J 11/B 22/J
SHR 019/036 016/037 013/033 015/035 015/034 017/037 016/032
20/B 00/B 11/B 01/B 22/J 11/B 22/J
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
311 AM CST WED DEC 12 2012
.SHORT TERM (TODAY-FRIDAY NIGHT)...MAIN CONCERNS WILL BE SNOW
AMOUNTS THROUGH THIS MORNING...AND THEN AGAIN TONIGHT INTO
THURSDAY MORNING. 00Z MODELS INITIALIZED WITH MINIMAL ERRORS...AND
IN DECENT AGREEMENT. WILL USE A BLEND FOR ANY DETAIL DIFFERENCES.
CURRENT LIGHT SNOW EVENT MAINLY DRIVEN BY 850MB WARM AIR
ADVECTION. MODELS INDICATE LIGHT SNOW ACROSS THE NORTHERN FA THIS
MORNING...WITH THE HIGHEST TOTALS (3-4 INCHES) JUST NORTH OF THE
INTERNATIONAL BORDER. 1-3 INCHES ACROSS THE NORTHERN FA STILL
LOOKS GOOD. WEAK SFC LOW TRACKS THROUGH THE MIDDLE OF THE FA
SETTING UP A DECENT TEMPERATURE GRADIENT FROM NORTH TO SOUTH
TODAY. LOWERED MAX TEMPS ACROSS THE NORTH A FEW DEGREES...AND
RAISED VALUES ACROSS THE SOUTH A FEW DEGREES. THE MAIN CHALLENGE
WILL BE IN BETWEEN WITH EXACTLY HOW FAR NORTH THE WARMER TEMPS
ACTUALLY OCCUR.
TONIGHT...THE POTENTIAL APPEARS TO BE INCREASING FOR SOME TYPE OF
BANDED SNOW EVENT. MODELS ALL INDICATE A BAND OF MID-LEVEL
FRONTOGENESIS COMBINED WITH SYNOPTIC LIFT. MODEL CROSS SECTIONS
INDICATE THE POTENTIAL FOR SYMMETRIC INSTABILITY...WHICH WOULD
INCREASE LIFT. PWATS WILL BE AROUND 0.40 INCHES. GIVEN THESE
FORCING MECHANISMS...MODELS LIKELY UNDER FORECASTING
QPF...ESPECIALLY THE LOWER RESOLUTION MODELS. THE 06Z NAM12 IS
INDICATING 0.30-0.40 INCHES WITHIN THIS BAND (LEADING TO 3-5
INCHES OF SNOWFALL WITH ISOLATED 6 INCH AMOUNTS)...WHICH SEEMS
CLOSEST TO WHAT SHOULD ACTUALLY OCCUR. THIS BAND WOULD BE VERY
NARROW...MAKING EXACT PLACEMENT A PROBLEM. NAM INDICATES THIS BAND
WILL OCCUR ALONG A LINE FROM DVL-GFK-BJI...WHILE THE
GFS/ECMWF/GEM INDICATE THIS BAND WILL OCCUR JUST NORTH OF A
VALLEY CITY TO FARGO TO PARK RAPIDS LINE. GIVEN THE HIGH
UNCERTAINTY IN PLACEMENT AND QPF AMTS...HOW TO FORECAST THIS EVENT
IS TRICKY. THE BEST COURSE OF ACTION IS LIKELY TO PLACE HIGHER
CHANCE POPS WITHIN THE MODEL CONSENSUS LOCATION (WITH LOWER POPS
NORTH AND SOUTH) AND NOT GO CRAZY WITH SNOWFALL AMOUNTS.
HOWEVER...WILL MENTION THE POSSIBILITY FOR HIGHER TOTALS IN THE
HWO AND ALLOW ANOTHER MODEL RUN OR TWO FOR HIGHER CONFIDENCE.
THURSDAY-FRIDAY NIGHT...HIGH PRESSURE MOVES INTO THE REGION ON
THURSDAY...AND LARGE SYSTEM BEGINS TO EJECT INTO THE CENTRAL
PLAINS FRIDAY NIGHT. MOSTLY DRY THIS PERIOD WITH TEMPERATURES
INCREASING A BIT EACH DAY/NIGHT.
.LONG TERM (SATURDAY-TUESDAY)...AN UPPER LEVEL SHORTWAVE TROUGH
WILL LIFT FROM THE CENTRAL PLAINS INTO THE SOUTHERN GREAT LAKES BY
LATE SATURDAY. THE ECMWF HAS BEEN THE MOST CONSISTENT WITH A MORE
NORTHERN TRACK OF THE SFC LOW UP INTO NORTHERN IOWA/SOUTHERN
WISCONSIN BY LATE SATURDAY...WITH THE GEM GENERALLY SHOWING A MORE
NORTHERN SOLUTION AS WELL. THE GFS HAS BEEN FARTHER SOUTH WITH
CONSIDERABLY MORE RUN-TO-RUN VARIABILITY. WITHOUT A LOT OF COLD
AIR AVAILABLE TO THE NORTH OF THE SYSTEM...A TRACK FARTHER NORTH
WOULD MAKE SENSE. A MORE NORTHERN SOLUTION WOULD INCREASE THE
CHANCE FOR ACCUMULATING SNOW ACROSS THE FAR SOUTHEAST PART OF THE
AREA...BUT CONFIDENCE IS STILL FAIRLY LOW REGARDING THE EXACT
TRACK OF THE STORM...AND HOW FAR NORTH AND WEST THE PRECIP WILL
GET. AS A RESULT...KEPT LOW POPS ACROSS THE SOUTHEAST HALF OF THE
AREA SAT/SAT NIGHT. HOWEVER...THIS SYSTEM WILL HAVE TO BE
MONITORED.
OTHERWISE...THE REST OF THE PERIOD LOOKS TO BE PRETTY QUIET. THE
SOUTHERN STREAM OF THE JET IS EXPECTED TO BE DOMINANT AND SUPPRESSED
ACROSS THE SOUTHERN CONUS...AS UPPER RIDGING DEVELOPS ACROSS EASTERN
CANADA. AS A RESULT...NO MAJOR WEATHER SYSTEMS ARE EXPECTED ACROSS
THE NORTHERN PLAINS. TEMPERATURES WILL REMAIN SEASONABLE...WITH NO
SIGNIFICANT INTRUSIONS OF COLD AIR.
&&
.AVIATION...AREA OF LIGHT SNOW ACROSS NORTHEAST NORTH DAKOTA INTO
NORTHWEST MINNESOTA WILL EXIT DURING THE MORNING HOURS. THERE IS A
BAND OF MVFR CIGS ACROSS EASTERN NORTH DAKOTA THAT WILL MOVE EAST
AND NORTH THROUGH THE DAY...AND THEN BACK SOUTH TONIGHT. WILL USE
THE LATEST RAP GUIDANCE FOR TIMING IN EACH TAF.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
TG/MAKOWSKI
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
729 AM EST WED DEC 12 2012
.SYNOPSIS...
A LARGE AREA OF HIGH PRESSURE WILL SETTLE OVER THE REGION FOR THE
REST OF THE WEEK. EXPECT DRY WEATHER WITH SEASONABLY COOL
TEMPERATURES AT FIRST AND A GRADUAL WARMING LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CLOUDS BEING STUBBORN IN THE UPSLOPE FLOW UNDER THE STILL-PRESENT
AND STILL-ALOFT INVERSION. NAM AND RUC BOTH CREATE CLEARING BUT
NOT FOR ANOTHER 6-9 HRS. SO IT SHOULD BE MORE-SUNNY BY NOON OVER
MOST OF THE AREA THANKS TO THE MEETING OF THE DRY AIR ALOFT AND A
WELL-MIXED BOUNDARY LAYER. WILL USE AN EQUAL MIX OF NAM AND GFS
MOS GUIDANCE FOR MAXES WHICH RETAINS CONTINUITY AND USUALLY
PERFORMS VERY WELL ON HIGH PRESSURE DAYS. THIS RESULTS IN LITTLE
TO NO CHANGE TO THE FORECAST TEMPS TODAY. VALUES WILL BE VERY
CLOSE TO NORMALS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
ALMOST NOTHING TO PICK OUT OF THE FORECAST AS A CHALLENGE/PROBLEM-
OF-THE-DAY FOR THE NEXT COUPLE OF DAYS WHILE THE 1030MB HIGH
PRESSURE RIDGE SITS RIGHT OVERHEAD. SOME EARLY MORNING RIVER
VALLEY FOG MAY FORM EACH MORNING IN THE NRN VALLEYS...BUT THE
AIRMASS IS VERY DRY. THUS...WILL NOT MENTION IT AT THIS POINT WITH
NO CERTAINTY IN THAT MATTER. OTHERWISE...HIGH/GREAT CERTAINTY LIES
IN THE SKY/WX/WIND/PRECIP FORECASTS FOR THE PERIOD. BIGGEST NEWS
WILL BE THE WARM UP FROM WED INTO THURS...AND THEN FOR FRIDAY.
HIGHS WILL RISE 3-5F EACH DAY IN MOST LOCATIONS AS THE BIG HIGH
SINKS TO THE SOUTH.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
LOW PRESSURE WILL EJECT NEWD FROM THE S/CNTRL PLAINS AND REACH
THE UPPER OH VALLEY/GREAT LAKES REGION BY 12Z SUNDAY. THE LATEST
MODEL AND ENSEMBLE GUIDANCE SHOWS SOME WEAK SECONDARY DEVELOPMENT
INTO MONDAY...AS ENERGY IS TRANSFERRED TO THE NRN MID-ATLANTIC/SRN
NEW ENGLAND COAST. THIS MILLER-B TYPE SCENARIO IS USUALLY NOT
FAVORABLE FOR SNOW...AS THE INITIAL WRN LOW TRACK ALLOWS WARM AIR
TO STREAM NEWD INTO THE AREA. 12Z ENSEMBLE 850MB TEMPS ARE ABOVE
0C OVER PA WITH RAIN/SNOW LINE TO THE NORTH. THE MAJORITY OF GEFS
PLUMES ALSO INDICATE A WARM SOLUTION. THEREFORE WILL MENTION RAIN
AS PRIMARY PTYPE FOR THE BULK OF THE UPCOMING WEEKEND PCPN
EVENT...WITH PERHAPS SOME SPOTTY -FZRA AT THE ONSET IF ENOUGH SUB-
FZG AIR CAN REMAIN ENTRENCHED EAST OF THE ALLEGHENIES. ANY CHANGE
IN THE LOW TRACK COULD ALTER THERMAL PROFILES. A WEAK AREA OF HIGH
PRES SHOULD LIMIT PCPN CHANCES EARLY NEXT WEEK WITH HIGHEST POPS
NEAR THE LWR GRT LKS DUE TO BRIEF NW FLOW TRAJECTORY. MEDIUM RANGE
DATA WANTS TO SPIN-UP ANOTHER LOW ALONG THE EAST COAST BY NEXT
WEDNESDAY...BUT THERE IS TOO MUCH SPREAD AND UNCERTAINTY THIS FAR
OUT TO GET EXCITED ABOUT A STORM.
&&
.AVIATION /13Z WEDNESDAY THROUGH SUNDAY/...
AREAS OF MVFR STRATOCU CONTINUE TO LINGER ACROSS HIGHER TERRAIN OF
THE WEST...AND WILL PERSIST FOR AT LEAST A COUPLE MORE HOURS
BEFORE LIFTING TO VFR. EVERYWHERE ELSE IS ALREADY VFR. AS RIDGE
CONTINUES TO BUILDS OVER THE REGION...SHOULD SEE INCREASING
SUNSHINE ALONG WITH LIGHT WINDS TODAY.
HIGH PRESSURE RIDGE SETTLES IN FOR THE NEXT SEVERAL DAYS...
BRINGING EXTENDED PERIOD OF PREVAILING VFR CONDITIONS.
OUTLOOK...
WED-SAT...NO SIG WX EXPECTED.
SAT NIGHT-SUN...FZRA POSS LATE SAT INTO EARLY SUNDAY...OTHERWISE
RAIN LIKELY.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO
SHORT TERM...DANGELO
LONG TERM...STEINBUGL
AVIATION...RXR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
623 AM EST WED DEC 12 2012
.SYNOPSIS...
A LARGE AREA OF HIGH PRESSURE WILL SETTLE OVER THE REGION FOR THE
REST OF THE WEEK. EXPECT DRY WEATHER WITH SEASONABLY COOL
TEMPERATURES AT FIRST AND A GRADUAL WARMING LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CLOUDS BEING STUBBORN IN THE UPSLOPE FLOW UNDER THE STILL-PRESENT
AND STILL-ALOFT INVERSION. NAM AND RUC BOTH CREATE CLEARING BUT
NOT FOR ANOTHER 6-9 HRS. SO IT SHOULD BE MORE-SUNNY BY NOON OVER
MOST OF THE AREA THANKS TO THE MEETING OF THE DRY AIR ALOFT AND A
WELL-MIXED BOUNDARY LAYER. WILL USE AN EQUAL MIX OF NAM AND GFS
MOS GUIDANCE FOR MAXES WHICH RETAINS CONTINUITY AND USUALLY
PERFORMS VERY WELL ON HIGH PRESSURE DAYS. THIS RESULTS IN LITTLE
TO NO CHANGE TO THE FORECAST TEMPS TODAY. VALUES WILL BE VERY
CLOSE TO NORMALS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
ALMOST NOTHING TO PICK OUT OF THE FORECAST AS A CHALLENGE/PROBLEM-
OF-THE-DAY FOR THE NEXT COUPLE OF DAYS WHILE THE 1030MB HIGH
PRESSURE RIDGE SITS RIGHT OVERHEAD. SOME EARLY MORNING RIVER
VALLEY FOG MAY FORM EACH MORNING IN THE NRN VALLEYS...BUT THE
AIRMASS IS VERY DRY. THUS...WILL NOT MENTION IT AT THIS POINT WITH
NO CERTAINTY IN THAT MATTER. OTHERWISE...HIGH/GREAT CERTAINTY LIES
IN THE SKY/WX/WIND/PRECIP FORECASTS FOR THE PERIOD. BIGGEST NEWS
WILL BE THE WARM UP FROM WED INTO THURS...AND THEN FOR FRIDAY.
HIGHS WILL RISE 3-5F EACH DAY IN MOST LOCATIONS AS THE BIG HIGH
SINKS TO THE SOUTH.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
LOW PRESSURE WILL EJECT NEWD FROM THE S/CNTRL PLAINS AND REACH
THE UPPER OH VALLEY/GREAT LAKES REGION BY 12Z SUNDAY. THE LATEST
MODEL AND ENSEMBLE GUIDANCE SHOWS SOME WEAK SECONDARY DEVELOPMENT
INTO MONDAY...AS ENERGY IS TRANSFERRED TO THE NRN MID-ATLANTIC/SRN
NEW ENGLAND COAST. THIS MILLER-B TYPE SCENARIO IS USUALLY NOT
FAVORABLE FOR SNOW...AS THE INITIAL WRN LOW TRACK ALLOWS WARM AIR
TO STREAM NEWD INTO THE AREA. 12Z ENSEMBLE 850MB TEMPS ARE ABOVE
0C OVER PA WITH RAIN/SNOW LINE TO THE NORTH. THE MAJORITY OF GEFS
PLUMES ALSO INDICATE A WARM SOLUTION. THEREFORE WILL MENTION RAIN
AS PRIMARY PTYPE FOR THE BULK OF THE UPCOMING WEEKEND PCPN
EVENT...WITH PERHAPS SOME SPOTTY -FZRA AT THE ONSET IF ENOUGH SUB-
FZG AIR CAN REMAIN ENTRENCHED EAST OF THE ALLEGHENIES. ANY CHANGE
IN THE LOW TRACK COULD ALTER THERMAL PROFILES. A WEAK AREA OF HIGH
PRES SHOULD LIMIT PCPN CHANCES EARLY NEXT WEEK WITH HIGHEST POPS
NEAR THE LWR GRT LKS DUE TO BRIEF NW FLOW TRAJECTORY. MEDIUM RANGE
DATA WANTS TO SPIN-UP ANOTHER LOW ALONG THE EAST COAST BY NEXT
WEDNESDAY...BUT THERE IS TOO MUCH SPREAD AND UNCERTAINTY THIS FAR
OUT TO GET EXCITED ABOUT A STORM.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AREAS OF MVFR STRATOCU LINGER ACROSS HIGHER TERRAIN OF THE
WEST...BUT EVERYWHERE ELSE IS VFR. AS RIDGE BUILDS OVER THE
REGION...EXPECT THESE CIGS TO GRADUALLY DISSIPATE AS OVERNIGHT
PROGRESSES.
HIGH PRESSURE TAKES OVER ON WED AS RIDGE SETTLES IN FOR THE NEXT
SEVERAL DAYS BRINGING PREVAILING VFR CONDITIONS.
OUTLOOK...
WED-FRI...NO SIG WX EXPECTED.
SAT-SUN...RAIN/FZRA POSSIBLE LATE SAT INTO EARLY SUNDAY.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO
SHORT TERM...DANGELO
LONG TERM...STEINBUGL
AVIATION...CERU/RXR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
404 AM EST WED DEC 12 2012
.SYNOPSIS...
A LARGE AREA OF HIGH PRESSURE WILL SETTLE OVER THE REGION FOR THE
REST OF THE WEEK. EXPECT DRY WEATHER WITH SEASONABLY COOL
TEMPERATURES AT FIRST AND A GRADUAL WARMING LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CLOUDS BEING STUBBORN IN THE UPSLOPE FLOW UNDER THE STILL-PRESENT
AND STILL-ALOFT INVERSION. NAM AND RUC BOTH DELAY THE CLEARING FOR
ANOTHER 6-9 HRS...BUT MAKE IT MUCH MORE-SUNNY BY NOON OVER MOST OF
THE AREA THANKS TO THE MEETING OF THE DRY AIR ALOFT AND A WELL-
MIXED BOUNDARY LAYER. WILL USE AN EQUAL MIX OF NAM AND GFS MOS
GUIDANCE FOR MAXES WHICH RETAINS CONTINUITY AND USUALLY PERFORMS
VERY WELL ON HIGH PRESSURE DAYS. THIS RESULTS IN LITTLE TO NO
CHANGE TO THE FORECAST TEMPS TODAY. VALUES WILL BE VERY CLOSE TO
NORMALS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
ALMOST NOTHING TO PICK OUT OF THE FORECAST AS A CHALLENGE/PROBLEM-
OF-THE-DAY FOR THE NEXT COUPLE OF DAYS WHILE THE 1030MB HIGH
PRESSURE RIDGE SITS RIGHT OVERHEAD. SOME EARLY MORNING RIVER
VALLEY FOG MAY FORM EACH MORNING IN THE NRN VALLEYS...BUT THE
AIRMASS IS VERY DRY. THUS...WILL NOT MENTION IT AT THIS POINT WITH
NO CERTAINTY IN THAT MATTER. OTHERWISE...HIGH/GREAT CERTAINTY LIES
IN THE SKY/WX/WIND/PRECIP FORECASTS FOR THE PERIOD. BIGGEST NEWS
WILL BE THE WARM UP FROM WED INTO THURS...AND THEN FOR FRIDAY.
HIGHS WILL RISE 3-5F EACH DAY IN MOST LOCATIONS AS THE BIG HIGH
SINKS TO THE SOUTH.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
LOW PRESSURE WILL EJECT NEWD FROM THE S/CNTRL PLAINS AND REACH
THE UPPER OH VALLEY/GREAT LAKES REGION BY 12Z SUNDAY. THE LATEST
MODEL AND ENSEMBLE GUIDANCE SHOWS SOME WEAK SECONDARY DEVELOPMENT
INTO MONDAY...AS ENERGY IS TRANSFERRED TO THE NRN MID-ATLANTIC/SRN
NEW ENGLAND COAST. THIS MILLER-B TYPE SCENARIO IS USUALLY NOT
FAVORABLE FOR SNOW...AS THE INITIAL WRN LOW TRACK ALLOWS WARM AIR
TO STREAM NEWD INTO THE AREA. 12Z ENSEMBLE 850MB TEMPS ARE ABOVE
0C OVER PA WITH RAIN/SNOW LINE TO THE NORTH. THE MAJORITY OF GEFS
PLUMES ALSO INDICATE A WARM SOLUTION. THEREFORE WILL MENTION RAIN
AS PRIMARY PTYPE FOR THE BULK OF THE UPCOMING WEEKEND PCPN
EVENT...WITH PERHAPS SOME SPOTTY -FZRA AT THE ONSET IF ENOUGH SUB-
FZG AIR CAN REMAIN ENTRENCHED EAST OF THE ALLEGHENIES. ANY CHANGE
IN THE LOW TRACK COULD ALTER THERMAL PROFILES. A WEAK AREA OF HIGH
PRES SHOULD LIMIT PCPN CHANCES EARLY NEXT WEEK WITH HIGHEST POPS
NEAR THE LWR GRT LKS DUE TO BRIEF NW FLOW TRAJECTORY. MEDIUM RANGE
DATA WANTS TO SPIN-UP ANOTHER LOW ALONG THE EAST COAST BY NEXT
WEDNESDAY...BUT THERE IS TOO MUCH SPREAD AND UNCERTAINTY THIS FAR
OUT TO GET EXCITED ABOUT A STORM.
&&
.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
AREAS OF MVFR STRATOCU LINGER ACROSS HIGHER TERRAIN OF THE
WEST...BUT EVERYWHERE ELSE IS VFR. AS RIDGE BUILDS OVER THE
REGION...EXPECT THESE CIGS TO GRADUALLY DISSIPATE AS OVERNIGHT
PROGRESSES.
HIGH PRESSURE TAKES OVER ON WED AS RIDGE SETTLES IN FOR THE NEXT
SEVERAL DAYS BRINGING PREVAILING VFR CONDITIONS.
OUTLOOK...
WED-FRI...NO SIG WX EXPECTED.
SAT-SUN...RAIN/FZRA POSSIBLE LATE SAT INTO EARLY SUNDAY.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO
SHORT TERM...DANGELO
LONG TERM...STEINBUGL
AVIATION...CERU/RXR
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
233 PM EST WED DEC 12 2012
.SYNOPSIS...
HIGH PRESSURE WILL PERSIST OVER THE AREA INTO SATURDAY. A FRONTAL
SYSTEM WILL THEN APPROACH THE NORTH CAROLINA MOUNTAINS EARLY SUNDAY
AND CROSS EAST OF THE FORECAST AREA BY EARLY MONDAY. ANOTHER FRONTAL
SYSTEM WILL APPROACH THE REGION ON TUESDAY.
&&
.NEAR TERM /THROUGH THURSDAY/...
STRONG UPPER DIVERGENCE IN THE ENTRANCE REGION OF A 130 KT POLAR JET
HAS RESULTED IN LIGHT RAIN OVER PARTS OF THE UPSTATE AND THE SRN NC
PIEDMONT. THE LATEST RUC SHOWS THE DIVERGENCE WEAKENING FOR A FEW
HOURS THIS AFTERNOON...THEN INCREASING OVER THE SRN HALF OF THE
FORECAST AREA AGAIN EARLY THIS EVENING AS A SHORT WAVE CURRENTLY
OVER MISSISSIPPI EJECTS QUICKLY TO THE NE. THE GFS ALSO HAS AN
IMPRESSIVE QPF MAX OVER THE SRN PART OF THE UPSTATE AND CHARLOTTE
METRO AREA FROM 00-06 UTC THIS EVENING. WHILE IT/S 0.25-0.50 INCH
RAINFALL AMOUNTS ARE ALMOST CERTAINLY TOO HIGH...LIGHT RAIN
SHOULD FILL BACK IN THIS EVENING ACROSS THE SAME AREAS THAT HAVE
BEEN SEEING IT THIS AFTERNOON. THIS WILL BASICALLY BE AREAS ALONG
AND SOUTH OF I-85. IT STILL APPEARS THAT THE RAIN WILL END BEFORE
TEMPERATURES FALL BELOW FREEZING TONIGHT AND I/M NOT ANTICIPATING
ANY P-TYPE PROBLEMS OVERNIGHT. EVEN DURING THE DAYLIGHT HOURS TODAY
THE PCPN SHOULD BE ALL RAIN. WHILE THE DUAL-POL HYDROMETEOR
CLASSIFICATION ALGORITHM IS SHOWING SOME MIXED PCPN OVER THE
CHARLOTTE METRO AREA...THIS IS UP AT 7KFT AND IS NOT REFLECTIVE OF
WHAT IS FALLING AT THE SFC. LAPS SOUNDINGS OVER THIS AREA SHOW AIR
TEMPS WELL ABOVE FREEZING IN THE LOWEST SEVERAL THOUSAND FEET OF THE
ATMOSPHERE.
CLOUDS WILL CLEAR OUT OF THE EASTERN ZONES EARLY TOMORROW AND WE
SHOULD SEE CLEAR BLUE SKIES AND SLIGHTLY BELOW NORMAL TEMPERATURES
FOR THURSDAY.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
AS OF 2 PM WEDNESDAY...SHORT RANGE MODELS INDICATE THAT THE
FORECAST AREA WILL REMAIN WITHIN THE CENTER OF 1025 MB SFC HIGH AND
UNDER DEEP RIDGING ALOFT. FORECAST SOUNDINGS INDICATE THAT WIDE
DEWPOINT DEPRESSIONS WILL EXIST FROM THE SFC TO THE
TROPOPAUSE...SUPPORTING A 0 PERCENT SKY COVER FORECAST FRIDAY
MORNING. HOWEVER...CIRRUS LEVEL MOISTURE WILL BEGIN TO INCREASE
DURING THE AFTERNOON...LIKELY SUPPORTING A FEW CONTRAILS OR THIN
CIRRUS. CALM WINDS...CLEAR SKY...AND DEEP DRY AIR WILL PROVIDE GOOD
RADIATIONAL COOLING CONDITIONS FRIDAY MORNING. USING A BLEND OF MOS
GUIDANCE...MIN TEMPERATURES SHOULD RANGE FROM THE MID 20S ACROSS THE
MTN VALLEYS TO THE L30S EAST. UNDER SUNNY TO MOSTLY SUNNY
CONDITIONS...HIGH TEMPERATURES ARE FORECAST TO RANGE FROM THE U50S
ACROSS THE MTNS TO THE L60S EAST.
FRIDAY NIGHT...CIRRUS CLOUD COVER WILL INCREASE THROUGH THE
NIGHT...POSSIBLY BECOMING GREATER THAN 5KFT THICK BY 12Z SAT. SFC
CONDITIONS WILL LIKELY REMAIN DRY WITH LIGHT AND VARIABLE TO CALM
WINDS. HOWEVER...THE INCREASING SKY COVER WILL FAVOR MIN
TEMPERATURES AROUND 5 DEGREES WARMER THAN EXPECTED FRIDAY MORNING.
ON SATURDAY...A COLD FRONT WILL APPROACH FROM THE WEST...LIKELY
REMAINING WEST OF THE APPALACHIAN THROUGH 0Z SUNDAY. HOWEVER...LIGHT
RETURN FLOW WILL DEVELOP ACROSS THE FORECAST AREA...RESULTING IN
WEAK WAA. FORECAST SOUNDINGS INDICATE THAT CLOUD BASES WILL LOWER TO
AROUND 10 KFT BY THE LATE AFTERNOON...REMAINING RATHER THICK ALOFT.
CLOUD COVER IS FORECAST TO BECOME MOSTLY CLOUDY BY THE AFTERNOON.
GIVEN THE WAA ON RETURN FLOW...TEMPERATURE GUIDANCE SUPPORTS HIGH
TEMPERATURES WITHIN A DEGREE OR TWO OF FRIDAY/S VALUES. A FEW PRE
FRONTAL RAIN SHOWERS MAY REACH THE EXTREME WESTERN NC MTNS DURING
THE EARLY EVENING HOURS ON SATURDAY...I WILL INDICATE CHC POPS WITH
LOW QPF.
&&
.LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/...
AS OF 230 PM WEDNESDAY...A COMPLEX WX PATTERN IS EXPECTED IN THE
MEDIUM RANGE...AS SPLIT UPPER FLOW IN THE WEST WILL BE QUITE
ACTIVE...AND THE MODELS DISAGREE ON THE DETAILS.
SATURDAY NIGHT AND SUNDAY...ALREADY PLENTY OF DISAGREEMENT WITH A
LEADING LOW PRES SYSTEM LIFTING NE ACRS THE MID MS VLY TO THE GREAT
LAKES...DRAGGING A COLD FRONT ACRS THE TN VLY TO THE SRN
APPALACHIANS. THE 12Z GFS IS SIMILAR TO PREV FEW RUNS IN BEING
MOISTURE-STARVED...WITH MORE VEERED LLVL FLOW AND WEAK ISENT LIFT.
MEANWHILE...THE 00Z ECMWF CONTINUES TO BE MUCH WETTER...WITH DEEP
SWLY FLOW TRANSPORTING GULF MOISTURE AHEAD OF THE FRONT...WITH
PLENTY OF LLVL LIFT. THE HPC GUIDE TAKES A BLEND OF THE GFS AND
ECMWF WITH THIS SYSTEM...WHICH RESULTS IN GENERALLY LOW-END
POPS...EXCEPT IN THE WEST WHERE THE BEST MOISTURE AND FORCING WILL
BE. TEMPS ARE EXPECTED TO BE TOO WARM FOR ANY WINTRY PRECIP WITH
THIS FIRST FRONT.
BOTH THE GFS AND ECMWF TAKE SOUTHERN STREAM SHORTWAVE ENERGY ACRS
THE SOUTHERN PLAINS...INDUCING WEAK CYCLOGENESIS ALONG A STALLED
FRONTAL BNDRY INVOF THE MID SOUTH. BUT THEY DIFFER ON THE
TIMING...WITH THE ECMWF ABOUT 12 HOURS FASTER. AN HPC BLEND WITH
PREVIOUS FCST WAS USED...RESULTING IN A SHOTGUN 30-40 POP FOR THREE
PERIODS FROM MONDAY THRU TUESDAY. THEN THINGS DRY OUT QUICKLY
TUESDAY NIGHT THRU WEDNESDAY. THIS ALSO RESULTS IN NO WINTRY PRECIP
IN THE FCST...AS CENTER OF LOW PRES LIFTS NE...KEEPING THE FA IN THE
WARM SECTOR. THERE MAY BE INSTBY AND SHEAR FOR SEVERE WX ACRS
PORTIONS OF THE PIEDMONT IF THE LOW IS STRONG ENUF AND TAKES THIS
KIND OF TRACK. AS I TYPED THIS...THE 12Z ECMWF CAME IN. IT HAS
ANOTHER SOUTHERN STREAM SYSTEM QUICKLY DEVELOP TUESDAY AND CROSS TO
OUR SOUTH...TURNING INTO A NOREASTER THAT RIDES UP THE EAST COAST
TUESDAY NIGHT THRU THURSDAY. THIS IS A NEW DEVELOPMENT...SO IS NOT
IN THIS FCST PACKAGE.
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
AT KCLT...LIGHT RAIN WILL OVERSPREAD THE AIRFIELD BETWEEN 17 AND 18
UTC THIS AFTERNOON. CIGS SHOULD HOLD AT OR A LITTLE ABOVE 2000 FEET
AS THE PRECIPITATION STARTS. IN FACT PERIODS OF LIGHT RAIN AND MVFR
CIGS WILL CONTINUE UNTIL AFTER MIDNIGHT. LATE TONIGHT CIGS WILL
CLEAR. WINDS WILL REMAIN OUT OF THE NE THROUGH THE VALID PERIOD OF
THE TAF. SPEEDS WILL AVERAGE AROUND 10 KTS...WITH OCCASIONAL GUSTS
UP TO 18 KTS.
ELSEWHERE...MVFR CIGS CONTINUE FROM KCLT TO JUST SOUTH OF KGMU AND
KGSP AND ACROSS KAND. THERE IS A NARROW BAND OF 4KFT VFR CIGS NORTH
OF THAT LINE...AND THEN JUST HIGH CIGS NORTH OF THAT. KHKY AND KAVL
SHOULD GENERALLY ONLY SEE HIGH CLOUDS INTO TONIGHT. OVER THE
UPSTATE...KGSP AND KGMU SHOULD HOLD NEAR 4KFT...BUT A LOWER CIG IS
POSSIBLE AT TIMES. THERE WILL ALSO BE PERIODS OF LIGHT RAIN...THOUGH
THE BULK OF THE RAIN WILL FALL SOUTH OF THE AIRFIELDS. WINDS WILL BE
OUT OF THE NE THROUGH THE TAF PERIOD AT SPEEDS OF 8 TO 10 KTS.
OUTLOOK...VFR CONDITIONS ARE EXPECTED THURSDAY AND FRIDAY THANKS TO
HIGH PRESSURE BUILDING IN FROM THE WEST. MOISTURE AND THE CHANCES OF
RESTRICTIONS WILL INCREASE OVER THE WEEKEND.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...JPT
NEAR TERM...MCAVOY
SHORT TERM...NED
LONG TERM...ARK
AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
531 PM CST THU DEC 13 2012
.SHORT TERM...TONIGHT THROUGH SUNDAY
323 PM CST THU DEC 13 2012
MAIN FORECAST CONCERNS ARE PRECIPITATION TYPES FRIDAY NIGHT INTO
SATURDAY.
LATEST WATER VAPOR SATELLITE IMAGERY SHOWING UPPER LEVEL TROUGH/LOW
OVER SOUTHWESTERN UNITED STATES AND WEST TO EAST ZONAL FLOW OVER
UPPER MIDWEST AND GREAT LAKES REGION. LATEST 20Z SURFACE ANALYSIS
INDICATES COLD FRONT EXTENDING OVER LAKE SUPERIOR TO WESTERN IOWA.
LATEST METARS OUT AHEAD OF THE FRONT SHOW TEMPERATURES IN THE LOWER
40S TO LOWER 50S AND BEHIND THE FRONT TEMPERATURES IN THE TEENS TO
MIDDLE 20S.
THE LATEST 13.12Z NAM IS SLIGHTLY MORE PROGRESSIVE WITH
SURFACE/UPPER LEVEL LOW EJECTING OUT INTO THE UPPER MIDWEST AND
GREAT LAKES REGION FRIDAY NIGHT INTO SATURDAY...THAN THE 13.12Z GFS.
HOWEVER...THE 13.12Z NAM DPROG/DT SHOWS SLIGHTLY SLOWER MOVEMENT AND
THE 13.12Z GFS DPROG/DT INDICATES BETTER RUN TO RUN CONSISTENCY THE
PAST FEW RUNS. THE DETERMINISTIC 13.12Z GFS/NAM ARE IN AGREEMENT
WARMER AIR ALOFT WILL ADVECT INTO THE AREA OUT AHEAD OF UPPER
LEVEL/SURFACE LOW AND PROVIDE POTENTIAL PROBLEMS FOR PRECIPITATION
TYPES ESPECIALLY OVER PORTIONS OF THE NORTHERN HALF OF THE FORECAST
AREA. CONFIDENCE IS LOW ON EXACT TIMING AND PLACEMENT OF
PRECIPITATION TYPES AND FRIDAY NIGHT INTO SATURDAY...OVERALL
CONFIDENCE IS INCREASING PARTS OF THE REGION WILL SEE SOME WINTRY
MIX OF PRECIPITATION LATE FRIDAY NIGHT INTO SATURDAY.
TONIGHT...WEAK COLD FRONT PUSHES SLOWLY INTO EASTERN WISCONSIN AND
EASTERN IOWA. A RELAXED PRESSURE GRADIENT WILL PRODUCE LIGHT WINDS
ACROSS FORECAST AREA...AS 13.12Z NAM/GFS BUFKIT SOUNDINGS SHOW LESS
THAN 10 KNOTS UP TO 3000 FEET ACROSS MUCH OF THE FORECAST AREA.
THE COMBINATION OF MELTING SNOW AND LIGHT WINDS WILL SATURATE THE
NEAR SURFACE BOUNDARY LAYER AND CAUSE LOW STRATUS DECK OR AREAS OF
FOG TO DEVELOP AFTER SUNSET. BIG QUESTION WILL BE HOW WIDESPREAD
AND DENSE FOG WILL BE. FOR NOW...HAVE CONTINUED PREVIOUS FORECAST OF
AREAS OF FOG AND INCREASED SKY COVER...ESPECIALLY OVER THE NORTHERN
HALF OF THE FORECAST AREA.
NEXT CONCERN IS POTENTIAL FOR PRECIPITATION TYPE FRIDAY NIGHT INTO
SATURDAY. THE DETERMINISTIC 13.12Z GFS/NAM ARE BOTH INDICATING WARMER
AIR ADVECTING NORTHWARD AHEAD OF THE SURFACE/UPPER LEVEL LOW INTO
THE REGION AND ARE IN OKAY AGREEMENT WITH THE PLACEMENT OF THE
SURFACE LOW...HOWEVER TIMING OF SURFACE LOW IS IN QUESTION. THE
DETERMINISTIC MODELS ARE INDICATING STRONG VERTICAL MOTION AND
ISENTROPIC LIFT IN ASSOCIATION WITH THE SURFACE/UPPER LEVEL LOW PER
CROSS SECTIONS. BUFKIT SOUNDINGS FROM BOTH THE NAM AND GFS SHOW MAX
TEMPERATURE ALOFT TO BE PLUS 4 TO 7 DEGREES CELSIUS BY 06Z SATURDAY
ACROSS MUCH OF THE FORECAST AREA. THE BUFKIT SOUNDINGS INDICATE
DIABATIC COOLING THROUGH THE ATMOSPHERE COLUMN FROM 06Z TO 12Z
SATURDAY...AS BETTER LIFT AND VERTICAL MOTION PUSHES ACROSS THE
NORTHERN HALF OF THE FORECAST AREA...ESPECIALLY OVER SOUTHEAST
MINNESOTA. THIS ALLOWS TEMPERATURES ALOFT TO COOL DOWN TO NEAR
FREEZING AND CAUSE THE POTENTIAL FOR THE PRECIPITATION TO MIX IN WITH
SNOW OR BE ALL SNOW OVER HIGHER TERRAIN AREAS OF SOUTHERN MINNESOTA
AND WESTERN WISCONSIN BY 12Z SATURDAY. HAVE INTRODUCED A RAIN SNOW
MIX OVER PARTS OF SOUTHEAST MINNESOTA SATURDAY MORNING...BASED ON
THIS. NORTH CENTRAL WISCONSIN WILL CONTINUE TO HAVE THE POTENTIAL TO
SEE A WINTRY MIX OF SNOW...SLEET...RAIN...AND POSSIBLY FREEZING RAIN
LATE FRIDAY NIGHT INTO SATURDAY. BUFKIT SOUNDINGS IN THIS AREA
SHOW COLDER TEMPERATURES ALOFT AND THE POTENTIAL FOR ALL SNOW WITH
SNOW ACCUMULATION OF 2 TO 4 INCHES AND LESS THAN A TENTH OF AN INCH
OF ICE ACCUMULATION. ALL RAIN SHOULD BE DOMINATE ACROSS PORTIONS OF
NORTHEAST IOWA AND EXTREME SOUTHERN WISCONSIN.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY
323 PM CST THU DEC 13 2012
MAIN FORECAST CONCERNS IS PRECIPITATION CHANCES SUNDAY NIGHT...THEN
AGAIN WEDNESDAY INTO THURSDAY. THE 13.00Z GFS/ECMWF/GEM ARE
IN AGREEMENT WITH THE REGION REMAINING UNDER THE INFLUENCE OF THE
UPPER LEVEL/SURFACE LOW OVER THE GREAT LAKES REGION SUNDAY NIGHT INTO
MONDAY. THIS WILL CONTINUE TO WRAP THE POSSIBILITY OF LIGHT SNOW OR
FLURRIES INTO THE EASTERN PARTS OF THE FORECAST AREA SUNDAY NIGHT
INTO MONDAY. THE DETERMINISTIC MODELS THEN BEGIN TO DIVERGE ON
TUESDAY WITH THE 13.00Z GEM MORE PROGRESSIVE IN DIGGING UPPER LEVEL
TROUGH AND DEVELOPING SURFACE LOW OVER CENTRAL PLAINS THAN THE 13.00Z
ECMWF/GFS. AT THIS TIME...WILL KEEP FORECAST AREA MAINLY DRY...AS THE
13.00Z GEFS SHOW UPPER LEVEL TROUGH FARTHER NORTH AND A SLOWER
SOLUTION. NEXT CONCERN IS THE 13.00Z GFS/ECMWF DIG UPPER LEVEL TROUGH
OVER THE UPPER MIDWEST AND GREAT LAKES REGION WEDNESDAY INTO
THURSDAY...HOWEVER BOTH THE MODELS DIFFER ON PLACEMENT AND TIMING OF
SURFACE LOW. THE DETERMINISTIC 13.00Z GFS/ECMWF INDICATE ENOUGH LIFT
AND SATURATION ASSOCIATED WITH UPPER LEVEL TROUGH/SURFACE LOW AND
WILL INTRODUCE SMALL PRECIPITATION CHANCES ACROSS FORECAST AREA.
&&
.AVIATION...TONIGHT AND FRIDAY
531 PM CST THU DEC 13 2012
MAIN CONCERN IS ON FOG AND STRATUS POTENTIAL TONIGHT WITH
MOISTENING BOUNDARY LAYER. MIXED SIGNALS IN MODELS REGARDING
FOG/LOW CLOUDS TONIGHT AS ONLY THE NAM BUFKIT SOUNDINGS SHOWING
LOW LEVEL SATURATION DUE TO THE MELTING SNOW-PACK. 14.21Z RAP AND
14.18Z GFS BOTH SHOW SOME SPREAD IN THE TEMPERATURES DEW POINTS
THROUGH THE OVERNIGHT HOURS. CONDITIONS LOOKS FAVORABLE WITH LIGHT
WINDS AND ONLY SOME HIGHER CLOUDS FROM TIME TO TIME. WITH
TEMPERATURES IN THE 30S AND 40S DID SEE SOME ADDITIONAL MELTING
TODAY WHICH SHOULD HELP TO SATURATE LOWEST LAYERS AS COLUMN COOLS.
VARIOUS WRF MODELS ALSO HINTING AT FOG/STRATUS...BUT GENERALLY
KEEP THIS AREA NORTH OF THE TAF SITES. DID KEEP IT IN THE 00Z
FORECASTS WITH IFR CONDITIONS...BUT DID DELAY THE ONSET A FEW HOURS. WILL
HAVE TO MONITOR THROUGH THE EVENING HOURS. OTHERWISE...PRESSURE
GRADIENT TIGHTENS FRIDAY AFTERNOON WITH SOUTHEAST WINDS PICKING UP
AND THIS SHOULD SCOUR OUT THE FOG AND LOW CLOUDS AFTER 18Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
323 PM CST THU DEC 13 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DTJ
LONG TERM....DTJ
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1037 PM MST THU DEC 13 2012
.AVIATION...
CLOUDS WILL BE INCREASING AND LOWERING ACRS THE AREA LATER TONIGHT
AND INTO FRI MORNING. RAP13 AND HRRR INDICATING SNOW MOVING INTO
THE KALS AREA AROUND 14Z...WITH THE POTENTIAL FOR SNOW THRU THE
DAY...BUT CHANCES DECREASING AND THEN ENDING IN THE EVENING. WITH
THE SNOW THERE SHOULD BE PERIODS OF IFR CONDITIONS. AT KPUB AND
KCOS THE FORECAST MODELS ARE MOVING PCPN INTO THE AREA AROUND 17Z-
18Z FRI AND THEN PCPN BEING POSSIBLE THRU THE DAY AND INTO THE
EVENING HOURS. CHANCES ARE THAT KPUB WILL SEE OCNL MVFR
CONDITIONS...WHILE KCOS HAS A BETTER CHANCE OF SEEING OCNL IFR
CONDITIONS IN PCPN.
&&
.PREV DISCUSSION... /ISSUED 615 PM MST THU DEC 13 2012/
SHORT TERM...
(TONIGHT AND FRIDAY)
..HEAVY SNOW FOR THE SAN JUANS TOMORROW...
CURRENTLY...AS IN PREVIOUS DAYS THIS WEEK...TEMPS SLOW TO REBOUND
FOR PUEBLO COUNTY AND THE ARKANSAS RIVER VALLEY. STILL SEEING LOWER
TO MID 40S AS OF MID DAY...WHILE FAR SERN PLAINS ARE ALREADY IN THE
60S. BKN HIGH CLOUDS CONTINUE TO MOVE OVER THE AREA IN ADVANCE OF
THE STORM SYSTEM OVER THE SRN CA COAST.
THIS STORM SYSTEM IS BOLSTERED BY A DEVELOPING SUBTROPICAL JET WHICH
WILL BE QUITE STRONG BY FRI...NR 160 KTS! EXTREME SRN PORTION OF CO
WILL BE IN FAVORABLE LEFT QUAD WITH STRONG QG LIFT AND FAVORABLE
DYNAMICS AS W-SW WINDS OF AROUND 50 KTS CRUISE JUST S OF THE 4
CORNERS. EXPECT A PERIOD OF INTENSE SNOWFALL OVER THE SAN JUANS IN
PARTICULAR...WITH SNOWFALL RATES OF UP TO 2 PER HOUR EXPECTED.
ALONG WITH STRONG WINDS...WINTER STORM WARNING FOR THE SW MTS
LOOKS ON TRACK. SNOWFALL FOR THE LOWER ELEVATIONS OF THE RIO GRANDE
DO NOT LOOK AS SPECTACULAR...BUT GIVEN THE DYNAMICS OF THE STORM
WILL MAINTAIN THE WARNING THERE AS WELL. ADVISORIES FOR THE BALANCE
OF THE MT AREAS LOOK ON TRACK...WITH 4-8 INCHES EXPECTED THERE.
MAIN QUESTION CONTINUES TO BE THE CHANCE OF SN FOR THE SAN LUIS
VALLEY AND ERN PLAINS. SRN PORTIONS OF THE VALLEY LOOK VERY FAVORABLE
FOR SOME MDT SNOW TOMORROW GIVEN THE UPPER DYNAMICS AND FAVORABLE
JET...SO HAVE BUMPED UP POPS A BIT THERE. KALS WILL BE ON THE NRN
EDGE OF EXPECTED HEAVIER SNOW...SO COULD SEE ANYTHING FROM LIGHT
ACCUMS TO POSSIBLY MODERATE ACCUMS IF STRONGER LIFT SHIFTS JUST A
BIT TO THE N. OVR THE PLAINS...NOT EXPECTING MUCH DUE TO THE
LACK OF UPSLOPE IN THE LOWER LEVELS. HOWEVER...MODELS...IN PARTICULAR
THE NAM...HAVE BEEN TRENDING TOWARDS A BIT MORE QPF OVER PORTIONS OF
THE PLAINS...AND THIS HAS BEEN PRETTY CONSISTENT FOR SEVERAL RUNS
NOW. SYSTEM LOOKS PRETTY IMPRESSIVE ON WV/IR IMAGES RIGHT NOW...AND
WOULD NOT BE SURPRISED IF DYNAMICS USURP OROGRAPHICS HERE AND GIVE
THE PLAINS A BRIEF SHOT OF SOME MDT SN TOMORROW. WILL STICK WITH
CONSERVATIVE POPS IN THE 30 PERCENT RANGE FOR NOW...BUT MAY
HAVE TO BUMP THINGS UP IF THE 00Z RUNS STILL SHOW THIS POTENTIAL.
TEMPS TOMORROW HIGHLY DEPENDENT ON PRECIP. CLOUD COVER WILL BE
PRETTY SOLID...AND WITH H7 TEMPS FALLING INTO THE MINUS 4 OR 5
RANGE...FEEL THAT MOS IS TOO HIGH...AND HAVE DROPPED HIGH TEMPS A
BIT INTO THE 40S FOR THE I-25 CORRIDOR. SHOULD BE A BIT WARMER FOR
THE ERN COUNTIES WITH A PRETTY GOOD TEMP/HUMIDITY GRADIENT SETTING
UP NR THE KS BORDER. FINALLY...LAPSE RATES LOOKING FAIRLY STEEP FRI
AFTERNOON OVER THE PLAINS...AND SPC HAS US IN THE GENERAL CONVECTIVE
OUTLOOK FOR TOMORROW. BEST CHANCE FOR TS WILL BE OVER LAS
ANIMAS...BACA...AND SRN PORTIONS OF PROWERS AND BENT COUNTIES AFTER
ABOUT 21Z. 44
LONG TERM...
(FRIDAY NIGHT THROUGH THURSDAY)
FRIDAY NIGHT THRU SATURDAY NIGHT...THE FIRST OF TWO WAVES WILL BE
EXITING THE FORECAST AREA BY 00Z SATURDAY. THE 12Z NAM/GFS/EC
BRING A CLOSED 500MB LOW THROUGH THE FAR SOUTHEAST CORNER OF
COLORADO BY 06Z...TAKING THE BULK OF THE DYNAMICS WITH IT
(INCLUDING A 120KT 300MB JET JUST TO OUR SOUTH AT THAT TIME). I
KEPT THUNDER IN THE FORECAST OVER PARTS OF KIOWA AND PROWERS
COUNTIES GIVEN THE DECENT 700-500MB LAPSE RATES (8-9C/KM). MODELS
BEGIN TO WIND DOWN QPF OVER THE CENTRAL MOUNTAINS...SAN
JUANS...AND LA GARITAS AFTER 06Z SATURDAY AND WILL LET WINTER
STORM WARNINGS AND WINTER WEATHER ADVISORIES IN THOSE AREAS EXPIRE
AT 09Z SATURDAY. MODELS SHOW A MUCH WEAKER...SECONDARY WAVE
MOVING EAST ACROSS NORTHERN NEW MEXICO LATE SATURDAY. THIS WILL
LIKELY CAUSE SOME BRIEF SNOW SHOWERS ACROSS THE SAN JUANS AND
CENTRAL MOUNTAINS...WITH ONLY ANOTHER 1 TO 3 INCHES POSSIBLE LATE
SATURDAY AFTERNOON AND EVENING.
SUNDAY...THE 12Z NAM AND GFS SHOW NORTHWEST FLOW OVER THE REGION
SUNDAY WITH SOME WEAK SHORTWAVES IN THE FLOW PASSING OVER THE
REGION. THIS WILL FAVOR SOME SNOW SHOWERS ACROSS THE CENTRAL
MOUNTAINS SUNDAY AFTERNOON AND EVENING WITH MINIMAL ACCUMULATIONS
EXPECTED.
MONDAY THROUGH TUESDAY NIGHT...THE FORECAST AREA WILL BE BETWEEN
SYSTEMS DURING THIS TIME. THE REGION WILL BE UNDER NORTHWEST FLOW
THROUGH EARLY TUESDAY...AND BEGIN TO TURN MORE WEST AND
SOUTHWESTERLY AS WEAK RIDGING SLOWLY BUILDS OVER THE REGION
TUESDAY AHEAD OF AN APPROACHING SYSTEM. 700MB TEMPERATURES WILL
WARM TO +3 TO +6 ACROSS THE I-25 CORRIDOR AND EASTERN PLAINS
TUESDAY AFTERNOON WHICH WILL LEAD TO HIGH TEMPERATURES IN THE
LOWER 50S IN THOSE AREAS. THE GFS AND EC MOVE THE RIDGE AXIS
ACROSS EASTERN COLORADO BY 00Z TUESDAY.
WEDNESDAY AND THURSDAY...THE GFS AND EC ARE IN DECENT AGREEMENT
ON A SHORTWAVE PASSING TO THE NORTH OF THE FORECAST AREA WEDNESDAY
AFTERNOON WITH A COLD FRONTAL PASSAGE ACROSS THE PLAINS BY 00Z
THURSDAY. THIS LOOKS TO BE A FAIRLY FAST MOVING SYSTEM WITH THE
BULK OF THE MOISTURE BEING CONFINED TO THE SAN JUANS AND CENTRAL
MOUNTAINS. 30 TO 40 POPS IN THOSE REGIONS SEEMED REASONABLE GIVEN
MODEL AGREEMENT AT THIS TIME. RIDGING WILL QUICKLY BUILD IN BEHIND
THIS SYSTEM BRINGING WEST AND SOUTHWESTERLY FLOW WITH DRY
CONDITIONS TO ALL OF THE FORECAST AREA. -PJC
AVIATION...
MAIN CONCERN CONTINUES TO BE ANTICIPATED IFR CONDITIONS AT KALS
FRI MORNING...GENERALLY FROM 12-18Z PERIOD...AS WELL AS LESSER
POTENTIAL FOR MVFR-IFR AT KCOS FOR THE SAME TIME PERIOD. CHANCES
FOR PRECIP REMAIN IN THE 50-60 PERCENT RANGE FOR KALS...AND 20-30
PERCENT FOR KPUB AND KCOS. RESTRICTIONS TO VIS/LOW CIGS MORE LIKELY
AT KCOS SO WILL CONTINUE EXPLICIT MENTION IN TAFS THERE...WITH VCSH
AT KPUB. HEAVY SNOW EXPECTED FOR THE SW MTS TOMORROW...AND LIGHT
TO MDT ACCUMS FOR THE OTHER MT RANGES. COULD ALSO SEE SOME ISOLD
TS FOR THE FAR SERN PLAINS...NR OK/CO AND CO/KS BORDERS AFTER
NOON TOMORROW. 44
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 2 AM FRIDAY TO 2 AM MST SATURDAY
FOR COZ060-064-073-075.
WINTER STORM WARNING FROM 2 AM FRIDAY TO 2 AM MST SATURDAY FOR
COZ066>068.
&&
$$
AREA FORECAST DISCUSSION
NWS CARIBOU ME
405 AM EST FRI DEC 14 2012
.SYNOPSIS...
WEAK LOW PRESSURE WILL PASS NORTH OF THE AREA THIS MORNING WITH A
COLD FRONTAL PASSAGE LATER TODAY AND TONIGHT. HIGH PRESSURE BUILDS
NORTH OF THE REGION SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
LOW PRESSURE IS CURRENTLY PASSING TO THE NORTH OF THE STATE. A
STRONG COLD FRONT TRAILING THE LOW WILL APPROACH FROM THE WEST
THIS MORNING THE MOVE ACROSS THE STATE DURING THE AFTERNOON.
STRONG COLD ADVECTION BEHIND THE FRONT ALONG WITH AN UPPER TROUGH
WILL RESULT IN UNSTABLE CONDITIONS RESULTING IN SNOW SQUALLS
...ESPECIALLY IN THE NORTH DURING THE AFTERNOON INTO THE EVENING.
WILL USE THE RUC13 TO INITIALIZE THE POP GRIDS THROUGH THE MORNING
THEN TRANSITION TO A BLEND OF THE NAM12 ...GFS40 ...SREF AND
ECMWF. FOR QPF WILL ALSO USE SAME MODEL BLEND AND EXCHANGE THE
NAM12 FOR NAM80. FOR SNOW AMOUNTS WILL RUN SNOW FROM THICKNESS
TOOL ON NAM/QPF GRIDS. THE GMOS WAS USED TO INITIALIZE THE
TEMPERATURE AND DEW POINT GRIDS. HAVE MANUALLY ADJUSTED MAXIMUM
AND MINIMUM TEMPERATURES. USED A NAM12/GMOS BLEND FOR WIND SPEED.
FOR WIND GUSTS WILL USE 200 PERCENT OF SUSTAINED SPEED WITH GOOD
MIXING EXPECTED.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
COLDER WEATHER IN STORE FOR THE WEEKEND.
ARCTIC AIR WILL CONTINUE TO PUSH INTO THE CWA ON SATURDAY W/NNW
WINDS ADDING A CHILL TO THE AIR. THIS WILL MEAN SATURDAY`S HIGHS
WILL BE BELOW NORMAL FOR THE IDES OF DECEMBER. A COLD NNW FLOW OFF
THE OPEN ST. LAWRENCE WILL LEAD TO CLOUDS ACROSS NORTHERN 1/2 OF
THE CWA W/SOME FLURRIES OR BANDS OF LIGHT SNOW THROUGH SATURDAY
AFTERNOON. THE NAM AND GFS TEND TO STRUGGLE W/THSI TYPE OF SETUP.
THE CANADIAN GEM LOOKS LIKE IT PICKS UP ON THIS WELL AND DECIDED
TO USE IT TO SET UP THE FORECAST FOR SATURDAY INTO SATURDAY NIGHT.
SKIES WILL GRADUALLY CLEAR ACROSS THE NORTHERN AREAS SATURDAY
NIGHT AS THE FLOW WEAKENS WHILE THE CENTRAL AND DOWNEAST REGION
REMAIN CLEAR. ALL THIS ALLOWING FOR SOME COLD TEMPERATURES BY
EARLY SUNDAY MORNING. STAYED CLOSE TO THE DAYCREW`S ASSESSMENT OF
READINGS AOB 0F ACROSS THE NORTH AND WEST AND IN THE SINGLE
NUMBERS FOR THE CENTRAL AND DOWNEAST REGIONS.
HIGH PRES WILL MOVE ACROSS NORTHERN QUEBEC AND RIDGE DOWN ACROSS
THE REGION ON SUNDAY. AT THE SAME TIME, LOW PRES MOVING ACROSS THE
GREAT LAKES REGION IS FCST TO RE-DEVELOP OFF THE NJ COAST BY
SUNDAY NIGHT. ATTM, DECIDED TO KEEP THE CWA DRY BANKING ON THE
STRONG HIGH TO THE NORTH HOLDING ON LONGER. THIS MATCHES UP WELL
THE LATEST RUNS OF THE NAM/GFS AND ECMWF. WE WILL SEE INCREASING
CLOUDS FROM THE SW DURING THE DAY W/A GRADUAL MODERATION IN
TEMPERATURES BUT STILL BELOW NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THINGS BEGIN TO GET COMPLICATED ESPECIALLY WEDNESDAY INTO
THURSDAY. DETAILS ARE BELOW.
THE 00Z RUNS OF THE ECMWF/OPERATIONAL GFS AND ITS MEAN ENSEMBLE
SUPPORT LOW PRES REDEVELOPING NEAR NJ SUNDAY NIGHT AND THEN SLOWLY
MOVING ENE OFF THE LONG ISLAND COAST. THE GFS IS MOST PROMINENT
W/THIS FEATURE WHILE THE ECWMF AND THE CANADIAN GLOBAL KEEP THE
SYSTEM LESS AMPLIFIED AND SHOW THE HIGH PRES RIDGE HOLDING ON
LONGER KEEPING THE BULK OF THE PRECIP FURTHER S. DECIDED TO BLEND
THE ECMWF AND GFS FOR THIS SYSTEM SUNDAY NIGHT INTO MONDAY. THIS MEANS
CHC POPS SUNDAY NIGHT FOR THE INTERIOR DOWNEAST AND COAST WHICH
MATCHES UP WELL W/GYX AND STAYED DRY FURTHER NORTH GIVEN THE
RIDGE HOLDING IN LONGER.
THE CHALLENGE NOW COMES FOR MONDAY RIGHT INTO LATE WEEK. THE
ECMWF DOES SHOW A MORE SIGNIFICANT LOW MOVING ACROSS THE DELMARVA
ON MONDAY AND LIFTING THROUGH THE GULF OF MAINE LATER TUESDAY INTO
WEDNESDAY AND THEN WEAKENS THIS LOW W/YET ANOTHER LOW FURTHER TO
THE E TAKING OVER BY THURSDAY AND ENDING THE PRECIP SOONER. THIS
WOULD MEAN SIGNIFICANT A SNOWFALL FOR THE CWA TUESDAY INTO WEDNESDAY
W/DRIER CONDITIONS ON THURSDAY. THE OPERATIONAL GFS HAS THIS LOW
DEVELOPING OFF THE MID ATLC COAST AND LIFTING NORTHWARD AND
INTENSIFYING W/POSSIBLE BLIZZARD CONDITIONS WEDNESDAY INTO
THURSDAY. TO ADD TO THE CONFUSION, 7 OUT OF THE 12 GFS ENSEMBLE
MEMBERS KEEP THIS LOW FURTHER S AND E BY THE SAME TIMEFRAME.
DECIDED TO GO W/LIKELY POPS(60-70%) FOR THE INTERIOR DOWNEAST AND
THE COAST FOR MONDAY INTO TUESDAY AND CHC POPS FURTHER NORTH.
TEMPERATURES LOOK COLD ENOUGH FOR SNOW ALL THE WAY TO THE COAST.
CONFIDENCE DROPS OFF WEDNESDAY INTO THURSDAY GIVEN THE
DISCREPANCIES IN THE LONG RANGE GUIDANCE. CONCERN IS THERE THAT
THE BLOCKING PATTERN SETTING UP OVER NORTHERN CANADA COULD LEAD TO
LOW PRES SYSTEMS BEING SHUNTED FURTHER S AND E. THEREFORE, KEPT
CHC POPS FOR THIS TIMEFRAME. THE DAYCREW CAN ASSESS THIS FURTHER
W/LATER MODEL RUNS. ADJUSTED THE GMOS MAXES DOWN WEDNESDAY INTO
THURSDAY BLENDING IN THE ECMWF TEMPERATURES. ALSO CUT BACK ON
WINDS SPEEDS FROM 40-50 MPH GUSTS DOWN TO 35 MPH. WOULD LIKE TO
SEE A BETTER CONSENSUS OF THE GUIDANCE BEFORE SHOOTING THAT HIGH.
&&
.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: BRIEF PERIOD OF MVFR/IFR CONDITIONS POSSIBLE DUE TO
SNOW SHOWERS AND CEILINGS ...OTHERWISE VFR CONDITIONS.
SHORT TERM: COULD BE SEEING SOME MVFR CONDITIONS FOR THE NORTHERN
TERMINALS SATURDAY AND THEN CONDITIONS LOOK LIKE THEY WILL GO VFR
THROUGH SUNDAY. THE CHALLENGE COMES MONDAY INTO TUESDAY W/A POSSIBLE
STORM SYSTEM BRINGING SNOW AND POSSIBLE ICING W/MVFR TO IFR.
&&
.MARINE...
NEAR TERM: HAVE USED A BLEND OF THE NAM12 AND GFS40 TO INITIALIZE
THE WINDS. HAVE INCREASED THE WIND SPEED SEVERAL KNOTS LATER
TONIGHT AS COLDER AIR MOVES ACROSS THE WATERS. FOR WAVES: EXPECT
SOUTHWEST FETCH TO DEVELOP ACROSS THE GULF OF MAINE THIS AFTERNOON
IN TIGHT GRADIENT AHEAD OF APPROACHING FRONT. PRIMARY WAVE GROUP
BUILDING TO 5-6 FEET/6 SECONDS. SECONDARY LONG PERIOD WAVE GROUP
FROM SOUTHEAST. WILL MOVE STARTING TIME FOR SCA TO 2100Z.
SHORT TERM: SCA CONDITIONS MAY NEED TO BE EXTENDED THROUGH
SATURDAY AFTERNOON AS NW WINDS COULD GUST TO 25 KTS W/CAA OVER THE
WATERS ESPECIALLY THE OUTER ZONES. USE A NAM12/GFS BLEND FOR THE
SUSTAINED WINDS SHOWING 15-20 KTS W/GUSTS HITTING 25 KTS ON
SATURDAY. WINDS DROP OFF SATURDAY NIGHT RIGHT THROUGH SUNDAY TO
10-15 KTS. SEAS WILL REMAIN 3-5 FT AT BEST FOR THIS TIME PERIOD.
WINDS/SEAS COULD INCREASE SIGNIFICANTLY MONDAY NIGHT INTO TUESDAY
AS A LOW PRES SYSTEM APCHS FORM THE S. ENE WINDS COULD HIT SCA OR
EVEN GALES. DECIDED TO BACK AWAY FROM THE GMOS ATTM AND CUT BACK
THOSE SPEEDS BY 10 KTS. THIS MEANS SUSTAINED WINDS OF 20-25 KTS
AND GUSTS UP TO 35 KTS. INCREASED THE SEAS UP TO 8-10 FT BY TUESDAY.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST
SATURDAY FOR ANZ050>052.
&&
$$
NEAR TERM...MIGNONE
SHORT TERM...HEWITT
LONG TERM...HEWITT
AVIATION...MIGNONE
MARINE...MIGNONE/HEWITT
AREA FORECAST DISCUSSION
NWS BILLINGS MT
910 PM MST THU DEC 13 2012
.SHORT TERM...VALID FOR FRI AND SAT...
ONLY MINOR CHANGES WERE MADE TO THE FORECAST FOR TONIGHT...MAINLY
TO ADJUST LOWS TOWARD OBSERVED DEWPOINTS AS OF MID EVENING BECAUSE
WEAK LOW-LEVEL FLOW AND LACK OF ANY REAL AIR MASS CHANGE WILL MAKE
THOSE NUMBERS A GOOD GUIDE. WE THUS LOWERED TEMPERATURES FOR PARTS
OF SOUTH CENTRAL MT...ESPECIALLY IN PLACES LIKE WILSALL AND JUDITH
GAP WHERE A COUPLE INCHES OF FRESH SNOW SHOULD LET THEM RADIATE TO
AROUND 10 F OVERNIGHT. IN CONTRAST...WE ACTUALLY RAISED LOWS A BIT
WHERE FOG AND STRATUS ARE IN PLACE...MAINLY EAST OF BILLINGS. THAT
FOG WILL BE THE MAIN WEATHER IMPACT TONIGHT AND FRI MORNING. DENSE
FOG WITH VISIBILITY OF ONE QUARTER MILE OR LESS IS LOCKED INTO THE
YELLOWSTONE RIVER VALLEY AND INTERSTATE 94 CORRIDOR...SO OUR DENSE
FOG ADVISORY IS ON TRACK IN THOSE AREAS. FORECAST SOUNDING DATA IS
SUPPORTIVE OF FOG AT MILES CITY THROUGH MOST OF THE NIGHT...THOUGH
WE STILL HAVE SOME CONCERN THAT LOWER SURFACE DEWPOINTS LOCATED TO
THE SOUTH COULD MOVE IN ON LIGHT SOUTHERLY WINDS AND ACTUALLY HELP
THE FOG LIFT OVERNIGHT. THE OTHER QUESTION ON OUR MINDS IS WHETHER
OR NOT THE DENSE FOG WILL EXPAND...ESPECIALLY AROUND BAKER...WHICH
SITS BETWEEN TWO AREAS OF LOW VISIBILITY AS OF 04 UTC. WE CHOSE TO
LEAVE FALLON COUNTY OUT OF THE DENSE FOG ADVISORY AT THIS POINT AS
RECENT TRENDS AT BAKER SUGGEST VISIBILITY MAY LARGELY STAY ABOVE A
MILE THERE...AN IDEA THAT IS SUPPORTED BY RECENT HRRR RUNS AND THE
18 UTC MAV AND 00 UTC MET MOS. SCHULTZ
.LONG TERM...VALID FOR SUN...MON...TUE...WED...THU...
THE BIG MESSAGE FOR THE EXTENDED IS PERSISTENT SNOW FOR AREA
MOUNTAINS...PARTICULARLY FOR WEST FACING SLOPES OF THE
BEARTOOTH/ABSAROKA MOUNTAINS. PACIFIC MOISTURE WILL FLOW PRETTY
MUCH CONSTANTLY OVER THESE AREAS FOR THE NEXT WEEK. INCREASED
POPS FOR THESE AREAS TO HIGH SCATTERED OR LIKELY THROUGH THE
PERIOD EXCEPT FOR WEDNESDAY NIGHT INTO THURSDAY. EXPECT AN INCH OR
TWO EACH DAY WITH 3 TO 6 INCHES WITH STRONGER WAVES EMBEDDED IN
THE PACIFIC MOISTURE FETCH. THIS COULD ADD UP TO WELL OVER A FOOT
OF NEW SNOW BY WEDNESDAY IN THE COOKE CITY AREA.
SUNDAY INTO MONDAY A NORTHERN STREAM WAVE PUSHES EASTWARD ALONG
THE CANADIAN BORDER. LOOKS LIKE ENOUGH CYCLONIC FLOW OVER THE AREA
TO BRING ISOLATED TO SCATTERED SNOW SHOWERS TO THE LOWER
ELEVATIONS. RIDGE BUILDS MONDAY AFTERNOON DRYING OUT LOWER
ELEVATIONS. ANOTHER ELONGATED PACIFIC TROF MOVES INTO THE ARE LATE
TUESDAY INTO WEDNESDAY FOR ANOTHER SHOT AT LOWER ELEVATION SNOW
SHOWERS. CYCLONIC FLOW OVER THE HUDSON BAY AREA ROTATES SOME
COLDER AIR INTO THE AREA FOR THURSDAY ALONG WITH INCREASED SNOW
CHANCES GOING INTO FRIDAY. ALTHOUGH SYSTEMS ALOFT ARE MOVING
THROUGH THE AREA PRETTY QUICKLY THE SURFACE PATTERN IS RATHER
STAGNANT WITH NOT MUCH WIND TO MOVE AIRMASSES IN OR OUT. AS A
RESULT LOOKING AT TEMPERATURES STAYING MAINLY IN THE 30S THROUGH
THE EXTENDED FOR HIGHS...WITH TEENS AND 20S FOR LOWS. COLDER AIR
LATE IN THE PERIOD COULD PUSH HIGHS INTO THE 20S. CHAMBERS
&&
.AVIATION...
AREAS OF FOG WILL CONTINUE TO IMPACT KMLS AND KBHK THROUGH FRIDAY
MORNING. EXPECT LIFR/VLIFR CONDITIONS. VFR CONDITIONS WILL PREVAIL
ELSEWHERE. ISOLATED SHOWERS WILL DEVELOP IN THE KLVM VICINITY BY
FRIDAY AFTERNOON. BRS
&&
.PRELIMINARY POINT TEMP/POPS...
FRI SAT SUN MON TUE WED THU
-----------------------------------------------------------
BIL 024/041 020/035 020/035 021/033 025/037 021/028 013/029
01/B 12/W 01/B 21/B 11/B 32/J 00/B
LVM 017/040 018/033 024/030 015/029 024/032 017/023 010/027
01/B 22/J 12/J 22/J 22/J 33/J 00/B
HDN 018/039 016/035 015/035 019/034 022/038 020/030 012/030
00/F 11/B 01/B 21/B 11/B 32/J 00/B
MLS 022/035 018/028 013/034 018/032 021/037 021/031 011/028
00/F 01/B 01/B 21/B 11/B 22/J 02/J
4BQ 020/037 017/034 015/035 019/034 021/037 021/032 013/031
00/F 11/B 00/U 21/B 00/B 21/B 02/J
BHK 017/038 014/027 011/031 018/031 019/036 021/030 012/026
00/F 01/B 00/B 21/B 11/B 21/B 02/J
SHR 017/040 017/033 015/034 019/034 021/036 019/028 012/029
00/B 12/J 11/B 21/B 01/B 22/J 00/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...DENSE FOG ADVISORY IN EFFECT UNTIL 11 AM MST FRIDAY FOR ZONES
30>32.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
350 AM CST FRI DEC 14 2012
.SHORT TERM (TODAY-SUNDAY NIGHT)...CLOUD TRENDS AND PRECIP
CHANCES/TYPE WILL BE THE CHALLENGE. 00Z MODELS INITIALIZED WITH
MINIMAL ERRORS...BUT CONTINUE TO SHOW DIFFERENCES THROUGH THE
PERIOD. THE ECMWF HAS BEEN MOST CONSISTENT RUN TO RUN AND WILL
FOLLOW FOR DETAILS.
UPPER TROUGH IS CRASHING THE SOUTHWEST CONUS AND WILL EJECT INTO
THE CENTRAL PLAINS TONIGHT.
FOR TODAY...SOUTHERLY LOW LEVEL FLOW WILL CONTINUE ALONG WITH WARM
AIR ADVECTION. 06Z RAP INDICATES 925MB WAA STRONGEST ACROSS THE
EASTERN FA...WITH 925MB DEWPOINTS NOT INCREASING MUCH. THIS WOULD
KEEP SKY MOSTLY CLOUDY WEST AND MOSTLY CLEAR EAST. IF THIS SKY
PREDICTION COMES TRUE...TEMPS WOULD LIKELY ONLY RISE A FEW
DEGREES ACROSS THE WEST...AND WOULD APPROACH THE FREEZING MARK
ACROSS THE EAST.
TONIGHT-SATURDAY...MODELS STILL HAVE DIFFERENCES WITH THE SPEED
AND TRACK OF THE MID-LEVEL TROUGH LEADING TO FAIRLY LOW
CONFIDENCE. THIS SYSTEM IS NOT THE STRONGEST...BUT THE GULF
APPEARS OPEN AND PWATS SHOULD BE OVER 0.5 INCH. THE MAIN FORCING
MECHANISM TO AFFECT THIS FA WILL BE DEFORMATION AS A 700MB LOW
TRACKS INTO NORTHERN MINNESOTA. A FEW QUESTIONS STILL
UNCERTAIN...1) HOW QUICKLY WILL HIGHER 925MB MOISTURE SURGE
NORTHWARD...2) P-TYPE AND FZRA POTENTIAL...3) HOW MUCH SNOW. THE
GFS IS THE QUICKEST BRINGING ABOVE 0C DEWPOINTS INTO THE EASTERN
FA TONIGHT. THIS WOULD LEAD TO A PROLONGED DZ/FZDZ SCENARIO BEFORE
DEFORMATION ZONE ARRIVES. ALL OTHER MODELS ARE NOT AS QUICK WITH
THIS MOISTURE SURGE...AND THE PROBABILITY FOR A PROLONGED PERIOD
OF FZDZ APPEARS LOW AT THIS POINT. AS THE MAIN PRECIP SHIED
ARRIVES INTO THE FA...THE 925-850MB LAYER WILL BE ABOVE FREEZING.
HOWEVER...EVAPORATIVE COOLING SHOULD QUICKLY CHANGE LIQUID PRECIP
TO SNOW...AND LIMIT FZRA. DID INSERT A SLIGHT CHANCE FOR FZRA INTO
THE WX GRIDS FOR 09Z-15Z SATURDAY. MODEL QPF SUGGESTS 1-3 INCHES
OF SNOW POSSIBLE ACROSS THE EASTERN FA. THE ABOVE SCENARIO IS WITH
FOLLOWING THE ECMWF...WHICH IS ONE SOLUTION OF MANY...HOPEFULLY
ANOTHER MODEL RUN CAN INCREASE CONFIDENCE WITH THE ABOVE
QUESTIONS.
MODELS APPEAR TO WANT TO KEEP MID-LEVEL CIRCULATION NEAR THE FA ON
SUNDAY...WHICH WOULD LEAD TO MORE CLOUDS AND POSSIBLE FLURRIES.
WILL NEED TO MONITOR THIS TREND IN THE MODELS.
.LONG TERM (MONDAY-THURSDAY)...
OVERALL...THERE IS PRETTY GOOD AGREEMENT AMONG THE MODELS WITH
OVERALL SYNOPTIC EVOLUTION OF THE PATTERN DURING THIS PERIOD...WITH
MORE UNCERTAINTY REGARDING THE FORECAST DETAILS. THE PERIOD WILL
BEGIN WITH WEAK SFC HIGH PRESSURE UNDER FAIRLY ZONAL FLOW ALOFT.
TEMPERATURES ON MONDAY AND TUESDAY ARE EXPECTED TO BE WITHIN A FEW
DEGREES OF SEASONAL NORMS. HAVE KEPT THESE DAYS MAINLY
DRY...ALTHOUGH WITH GUIDANCE SHOWING WEAK UPPER WAVES CASCADING
THROUGH THE FLOW...A BIT OF LIGHT SNOW COULD NOT BE RULED OUT.
IT APPEARS THAT A RELATIVELY PROGRESSIVE LONGWAVE TROUGH WILL SHIFT
FROM THE ROCKIES INTO THE PLAINS DURING THE MIDDLE OF NEXT WEEK.
THIS WOULD SUPPORT THE DEVELOPMENT OF A LEE CYCLONE ACROSS COLORADO
LIFTING INTO THE PLAINS. THE 00Z GFS IS MORE PROGRESSIVE AND LESS
AMPLIFIED THAN THE 00Z ECMWF/GEM WITH THIS FEATURE. A MORE AMPLIFIED
SOLUTION SUCH AS THE ECMWF/GEM WOULD SUPPORT STRONGER SFC
CYCLOGENESIS SOMEWHERE ACROSS THE PLAINS. HOWEVER...MODEL SPREAD IS
LARGE AT THIS RANGE...SO CONFIDENCE IN THE EVOLUTION OF THE SYSTEM
IS LOW. TEMPS LOOK TO REMAIN SEASONABLE AHEAD OF THE SYSTEM...WITH
COOLING EXPECTED IN ITS WAKE BACK BELOW NORMAL.
&&
.AVIATION...THE GENERAL TREND WILL BE CLEARING FROM SOUTH TO NORTH
ACROSS MINNESOTA...WITH LOW CLOUDS REMAINING ACROSS NORTH DAKOTA.
KGFK WILL BE THE TRICKIEST AS THEY WILL BE ON THE EDGE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
TG/MAKOWSKI
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
317 AM CST FRI DEC 14 2012
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
317 AM CST FRI DEC 14 2012
THE MAIN FOCUS THROUGH THE WEEKEND IS WITH THE SYSTEM MOVING IN
TONIGHT THAT WILL LINGER THROUGH MUCH OF THE WEEKEND WITH THE
QUESTION BEING WHAT TYPE OF PRECIPITATION WILL FALL AS IT MOVES
THROUGH.
MAINLY ZONAL FLOW ALOFT IS IN PLACE THROUGH THE EASTERN HALF OF
THE US WHILE A CLOSED LOW MOVES INTO THE FOUR CORNERS REGION. AT
THE SURFACE...A RIDGE OF HIGH PRESSURE EXTENDS SOUTH FROM HUDSON
BAY THROUGH LAKE SUPERIOR AND THE UPPER MISSISSIPPI RIVER VALLEY.
A BAND OF CIRRUS HAS MOVED THROUGH ALONG THE RIGHT ENTRANCE REGION
OF THE UPPER LEVEL JET WHILE A BAND OF STRATUS/FOG HAS DROPPED
SOUTH OUT OF LAKE SUPERIOR AHEAD OF THE SURFACE RIDGE AXIS.
VISIBILITY HAS MAINLY BEEN ABOVE 2SM WITH THIS FOG...THOUGH ON THE
LEADING EDGE THERE HAS BEEN SOME PATCHY DENSE FOG THAT HAS FORMED.
TEMPERATURES ARE IN THE 20-28F RANGE IN THIS AREA...SO SOME SLICK
SPOTS WILL BE POSSIBLE THIS MORNING UNDER THIS FOG...THOUGH TAYLOR
COUNTY SHERIFF HAD REPORTED THAT THEY HAVE NOT HEARD OF ANY ISSUES
AS OF 2AM. WITH THE PRESSURE GRADIENT TIGHTENING TODAY AND THE
TROUGH EJECTING INTO THE CENTRAL PLAINS...SHOULD HAVE JUST HIGH
LEVEL CLOUD COVER TO CONTEND WITH AND TEMPERATURES CLIMBING INTO
THE 40S.
THE CLOSED MID LEVEL AND SURFACE LOW WILL MAKE THEIR WAY THROUGH
THE CENTRAL PLAINS TODAY INTO TONIGHT WITH PRECIPITATION MOVING
NORTH AND REACHING NORTHEAST IOWA AROUND OR JUST AFTER MIDNIGHT.
THE 14.00Z NAM/HI-RES ARW/NMM ARE A TAD SLOWER WITH THE
PROPAGATION NORTHEASTWARD OF THE PRECIPITATION BAND OVERNIGHT
COMPARED TO THE 14.00Z GFS/ECMWF/GEM...SO HAVE TRENDED A LITTLE
SLOWER WITH THE PRECIPITATION MOVING IN. THE INITIAL QUESTION IS
WITH SURFACE TEMPERATURES AND WHETHER THEY WILL BE AT OR BELOW
FREEZING AS THIS PRECIPITATION MOVES IN SINCE IT WILL BE RAIN THAT
FALLS THROUGH DAY BREAK WITH A LOW LEVEL WARM LAYER PUSHING +6C
REGION-WIDE. WITH THE LOW LEVEL FLOW STAYING OUT OF THE
SOUTH...THE MAIN AREA OF CONCERN APPEARS TO BE IN NORTH CENTRAL
WISCONSIN WHERE THE SNOW PACK IS A LITTLE DEEPER AND COULD KEEP
TEMPERATURES AROUND FREEZING. EVEN SO...AS THE RAIN BEGINS THE
LATENT HEAT RELEASE SHOULD PUSH SURFACE TEMPERATURES UP A FEW
DEGREES...LIKELY BACK ABOVE FREEZING. HAVE BACKED OFF A BIT ON THE
FREEZING RAIN POTENTIAL AS A RESULT.
THE NEXT QUESTION IS WITH SATURDAY MORNING WITH WHETHER OR NOT
THERE WILL BE A PERIOD OF SNOW ACROSS SOUTHEAST MINNESOTA AND
WESTERN WISCONSIN. THE 14.00Z GFS IS THE WARMEST SOLUTION AND
SUGGEST THAT P-TYPE WILL REMAIN ALL RAIN IN THE MORNING...BUT THE
14.00Z NAM/HI-RES ARW/NMM RUNS SHOW THAT AS THE PRECIPITATION
STARTS TO FALL IT WILL COOL DOWN THE WARM LAYER TO THE WET BULB
TEMPERATURE...WHICH IS RIGHT AROUND 0C. SHOULD THIS HAPPEN...THE
THERMAL PROFILE WOULD SUGGEST THAT SNOW WOULD FALL UNTIL WARMER
LOW LEVEL AIR MOVES IN LATER IN THE MORNING AS THE SURFACE/LOW
LEVEL LOW MOVES IN. HAVE ADDED SOME CHANCES FOR LIGHT SNOW IN
THERE WITH MINOR ACCUMULATIONS IN THE MORNING WITH THE HIGHEST
AMOUNTS FALLING IN NORTH CENTRAL WISCONSIN IN THE 1-3 INCH RANGE.
AFTER THE DEEP FORCING WANES IN THE AFTERNOON/EVENING
SATURDAY...THERE COULD BE A PERIOD OF DRIZZLE THAT OCCURS WITH THE
COLUMN LOSING ICE GENERATIONS...THOUGH TEMPERATURES SHOULD BE
WARM ENOUGH INITIALLY FOR IT NOT TO FREEZE. WILL HAVE TO WATCH THE
PERIOD AS THE RAIN TRANSITIONS TO SNOW AND WHETHER THERE WOULD BE
ANY FREEZING DRIZZLE THAT MIXES IN BETWEEN THE PRECIPITATION
PERIODS. CONFIDENCE IS NOT HIGH ENOUGH AT THIS POINT TO INTRODUCE
THE DRIZZLE...SO HAVE JUST LEFT IT AS A TRANSITION FROM RAIN TO
SNOW. THE SURFACE LOW WILL THEN SLOWLY TRACK TO THE EAST TOWARD
LAKE MICHIGAN ON SUNDAY WITH SOME LIGHT PRECIPITATION POSSIBLY
LINGERING AS WELL.
.LONG TERM...MONDAY THROUGH THURSDAY
317 AM CST FRI DEC 14 2012
THE EXTENDED PERIOD WILL START OUT ON THE BACK SIDE OF THE WEEKEND
SYSTEM WITH NORTHWESTERLY FLOW IN PLACE FROM THE SURFACE AND
ALOFT. A TRAILING SHORTWAVE TROUGH COULD LEAD TO SOME LIGHT SNOW
IN WISCONSIN ON MONDAY..BUT THE OVERALL FORCING BETWEEN THE 14.00Z
GFS/ECMWF IS RATHER WEAK AND BETTER TO THE EAST...SO AM NOT
EXPECTING MUCH OUT OF THIS FEATURE.
THE COOL LOW LEVEL AIR MASS WILL PROPAGATE EASTWARD ON TUESDAY AS
THE NEXT TROUGH MOVES INTO THE NORTHERN PLAINS ON WEDNESDAY.
WARMER LOW LEVEL AIR WILL START NOSING UP INTO THE REGION ON
TUESDAY/TUESDAY NIGHT WITH THE 14.00Z ECMWF/GEM SUGGESTING THAT
SOME PRECIPITATION COULD FORM ALONG THIS LOW LEVEL TEMPERATURE
GRADIENT. CONFIDENCE NOT HIGH ENOUGH TO PUT IT IN THE FORECAST
RIGHT NOW...BUT WILL HAVE TO MONITOR TRENDS WITH THIS FEATURE.
SOME DIFFERENCES CONTINUE BETWEEN THE 14.00Z GFS/ECMWF/GEM ON
WEDNESDAY WITH THE POSITION OF THE SURFACE LOW WITH THE GFS
APPEARING TO BE A FAST OUTLIER WITH THE LOW BEING INTO CENTRAL
IOWA WHILE THE ECMWF/GEM HAVE THE LOW IN WESTERN KANSAS. DESPITE
THE DIFFERENCES IN TIMING/PLACEMENT OF THE LOW...THE TIMING IS NOT
TOO FAR OFF WITH THE PRECIPITATION MOVING IN ON WEDNESDAY NIGHT
INTO THURSDAY. THE GFS DOES LOOK A TAD COOLER WITH ITS THERMAL
PROFILE AND WOULD MEAN MORE OF A SNOW EVENT WHERE THE ECMWF WOULD
SUGGEST MORE RAIN WITH A WARMER NEAR SURFACE LAYER. WILL HAVE TO
IRON OUT THOSE DETAILS AS WE GET CLOSER...BUT BASED ON THESE
THERMAL PROFILES LOOKING MORE LIKELY TO PRODUCE SNOW...HAVE JUST
LEFT THE PRECIPITATION TYPE AS ALL SNOW OVER THIS TIME PERIOD.
ANOTHER SHOT OF COLD AIR FOLLOWS THIS SYSTEM WITH 850MB
TEMPERATURES LIKELY DROPPING BACK DOWN TO AROUND -10C BY FRIDAY.
&&
.AVIATION...THROUGH 06Z SATURDAY
1131 PM CST THU DEC 13 2012
AT 05Z HIGH PRESSURE WAS CENTERED OVER CENTRAL MINNESOTA...WHERE
SKIES WERE CLEAR. FOG AND SOME STRATUS HAD FORMED ON THE SOUTHERN
EDGE OF THE HIGH FROM CENTRAL MINNESOTA INTO NORTH CENTRAL
WISCONSIN. NEAR TERM CONCERNS REMAIN ON FOG/STRATUS POTENTIAL
THROUGH THE OVERNIGHT HOURS. 14.03Z RAP SOUNDINGS CONTINUE TO
INDICATE LOW LEVEL SATURATION REMAINS NORTH OF THE TAF SITES AND
THUS EXPECT THE LOWEST VISIBILITIES IN THESE AREAS. 14.00Z NAM HAS
ALSO BACKED AWAY FROM THE BOUNDARY LAYER SATURATION AT KLSE AND
KRST. GIVEN CURRENT TEMPERATURES/DEW POINT SPREADS OF 2 TO 3
DEGREES AT KLSE AND KRST DO FEEL SOME FOG IS LIKELY AT THE TAF
SITES...MAINLY IN THE MVFR CATEGORY AND WILL USE A TEMPO GROUP FOR
IFR CONDITIONS BETWEEN 08Z-12Z. PRESSURE GRADIENT DOES TIGHTEN BY
MID MORNING AND SHOULD SCOUR OUT ANY REMAINING STRATUS AND FOG
WITH VFR CONDITIONS THROUGH AT LEAST 02Z. BETWEEN 02Z-06Z AN AREA
OF LOW PRESSURE WILL LIFT OUT OF THE PLAINS TOWARDS THE AREA. AT
THIS TIME IT LOOKS LIKE ANY PRECIPITATION AT THE SITES WILL BE
AFTER 06Z...WITH JUST LOWERING CEILINGS IN THE 02Z-06Z TIME
FRAME...POSSIBLY INTO MVFR BY 06Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
317 AM CST FRI DEC 14 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1131 PM CST THU DEC 13 2012
.SHORT TERM...TONIGHT THROUGH SUNDAY
323 PM CST THU DEC 13 2012
MAIN FORECAST CONCERNS ARE PRECIPITATION TYPES FRIDAY NIGHT INTO
SATURDAY.
LATEST WATER VAPOR SATELLITE IMAGERY SHOWING UPPER LEVEL TROUGH/LOW
OVER SOUTHWESTERN UNITED STATES AND WEST TO EAST ZONAL FLOW OVER
UPPER MIDWEST AND GREAT LAKES REGION. LATEST 20Z SURFACE ANALYSIS
INDICATES COLD FRONT EXTENDING OVER LAKE SUPERIOR TO WESTERN IOWA.
LATEST METARS OUT AHEAD OF THE FRONT SHOW TEMPERATURES IN THE LOWER
40S TO LOWER 50S AND BEHIND THE FRONT TEMPERATURES IN THE TEENS TO
MIDDLE 20S.
THE LATEST 13.12Z NAM IS SLIGHTLY MORE PROGRESSIVE WITH
SURFACE/UPPER LEVEL LOW EJECTING OUT INTO THE UPPER MIDWEST AND
GREAT LAKES REGION FRIDAY NIGHT INTO SATURDAY...THAN THE 13.12Z GFS.
HOWEVER...THE 13.12Z NAM DPROG/DT SHOWS SLIGHTLY SLOWER MOVEMENT AND
THE 13.12Z GFS DPROG/DT INDICATES BETTER RUN TO RUN CONSISTENCY THE
PAST FEW RUNS. THE DETERMINISTIC 13.12Z GFS/NAM ARE IN AGREEMENT
WARMER AIR ALOFT WILL ADVECT INTO THE AREA OUT AHEAD OF UPPER
LEVEL/SURFACE LOW AND PROVIDE POTENTIAL PROBLEMS FOR PRECIPITATION
TYPES ESPECIALLY OVER PORTIONS OF THE NORTHERN HALF OF THE FORECAST
AREA. CONFIDENCE IS LOW ON EXACT TIMING AND PLACEMENT OF
PRECIPITATION TYPES AND FRIDAY NIGHT INTO SATURDAY...OVERALL
CONFIDENCE IS INCREASING PARTS OF THE REGION WILL SEE SOME WINTRY
MIX OF PRECIPITATION LATE FRIDAY NIGHT INTO SATURDAY.
TONIGHT...WEAK COLD FRONT PUSHES SLOWLY INTO EASTERN WISCONSIN AND
EASTERN IOWA. A RELAXED PRESSURE GRADIENT WILL PRODUCE LIGHT WINDS
ACROSS FORECAST AREA...AS 13.12Z NAM/GFS BUFKIT SOUNDINGS SHOW LESS
THAN 10 KNOTS UP TO 3000 FEET ACROSS MUCH OF THE FORECAST AREA.
THE COMBINATION OF MELTING SNOW AND LIGHT WINDS WILL SATURATE THE
NEAR SURFACE BOUNDARY LAYER AND CAUSE LOW STRATUS DECK OR AREAS OF
FOG TO DEVELOP AFTER SUNSET. BIG QUESTION WILL BE HOW WIDESPREAD
AND DENSE FOG WILL BE. FOR NOW...HAVE CONTINUED PREVIOUS FORECAST OF
AREAS OF FOG AND INCREASED SKY COVER...ESPECIALLY OVER THE NORTHERN
HALF OF THE FORECAST AREA.
NEXT CONCERN IS POTENTIAL FOR PRECIPITATION TYPE FRIDAY NIGHT INTO
SATURDAY. THE DETERMINISTIC 13.12Z GFS/NAM ARE BOTH INDICATING WARMER
AIR ADVECTING NORTHWARD AHEAD OF THE SURFACE/UPPER LEVEL LOW INTO
THE REGION AND ARE IN OKAY AGREEMENT WITH THE PLACEMENT OF THE
SURFACE LOW...HOWEVER TIMING OF SURFACE LOW IS IN QUESTION. THE
DETERMINISTIC MODELS ARE INDICATING STRONG VERTICAL MOTION AND
ISENTROPIC LIFT IN ASSOCIATION WITH THE SURFACE/UPPER LEVEL LOW PER
CROSS SECTIONS. BUFKIT SOUNDINGS FROM BOTH THE NAM AND GFS SHOW MAX
TEMPERATURE ALOFT TO BE PLUS 4 TO 7 DEGREES CELSIUS BY 06Z SATURDAY
ACROSS MUCH OF THE FORECAST AREA. THE BUFKIT SOUNDINGS INDICATE
DIABATIC COOLING THROUGH THE ATMOSPHERE COLUMN FROM 06Z TO 12Z
SATURDAY...AS BETTER LIFT AND VERTICAL MOTION PUSHES ACROSS THE
NORTHERN HALF OF THE FORECAST AREA...ESPECIALLY OVER SOUTHEAST
MINNESOTA. THIS ALLOWS TEMPERATURES ALOFT TO COOL DOWN TO NEAR
FREEZING AND CAUSE THE POTENTIAL FOR THE PRECIPITATION TO MIX IN WITH
SNOW OR BE ALL SNOW OVER HIGHER TERRAIN AREAS OF SOUTHERN MINNESOTA
AND WESTERN WISCONSIN BY 12Z SATURDAY. HAVE INTRODUCED A RAIN SNOW
MIX OVER PARTS OF SOUTHEAST MINNESOTA SATURDAY MORNING...BASED ON
THIS. NORTH CENTRAL WISCONSIN WILL CONTINUE TO HAVE THE POTENTIAL TO
SEE A WINTRY MIX OF SNOW...SLEET...RAIN...AND POSSIBLY FREEZING RAIN
LATE FRIDAY NIGHT INTO SATURDAY. BUFKIT SOUNDINGS IN THIS AREA
SHOW COLDER TEMPERATURES ALOFT AND THE POTENTIAL FOR ALL SNOW WITH
SNOW ACCUMULATION OF 2 TO 4 INCHES AND LESS THAN A TENTH OF AN INCH
OF ICE ACCUMULATION. ALL RAIN SHOULD BE DOMINATE ACROSS PORTIONS OF
NORTHEAST IOWA AND EXTREME SOUTHERN WISCONSIN.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY
323 PM CST THU DEC 13 2012
MAIN FORECAST CONCERNS IS PRECIPITATION CHANCES SUNDAY NIGHT...THEN
AGAIN WEDNESDAY INTO THURSDAY. THE 13.00Z GFS/ECMWF/GEM ARE
IN AGREEMENT WITH THE REGION REMAINING UNDER THE INFLUENCE OF THE
UPPER LEVEL/SURFACE LOW OVER THE GREAT LAKES REGION SUNDAY NIGHT INTO
MONDAY. THIS WILL CONTINUE TO WRAP THE POSSIBILITY OF LIGHT SNOW OR
FLURRIES INTO THE EASTERN PARTS OF THE FORECAST AREA SUNDAY NIGHT
INTO MONDAY. THE DETERMINISTIC MODELS THEN BEGIN TO DIVERGE ON
TUESDAY WITH THE 13.00Z GEM MORE PROGRESSIVE IN DIGGING UPPER LEVEL
TROUGH AND DEVELOPING SURFACE LOW OVER CENTRAL PLAINS THAN THE 13.00Z
ECMWF/GFS. AT THIS TIME...WILL KEEP FORECAST AREA MAINLY DRY...AS THE
13.00Z GEFS SHOW UPPER LEVEL TROUGH FARTHER NORTH AND A SLOWER
SOLUTION. NEXT CONCERN IS THE 13.00Z GFS/ECMWF DIG UPPER LEVEL TROUGH
OVER THE UPPER MIDWEST AND GREAT LAKES REGION WEDNESDAY INTO
THURSDAY...HOWEVER BOTH THE MODELS DIFFER ON PLACEMENT AND TIMING OF
SURFACE LOW. THE DETERMINISTIC 13.00Z GFS/ECMWF INDICATE ENOUGH LIFT
AND SATURATION ASSOCIATED WITH UPPER LEVEL TROUGH/SURFACE LOW AND
WILL INTRODUCE SMALL PRECIPITATION CHANCES ACROSS FORECAST AREA.
&&
.AVIATION...THROUGH 06Z SATURDAY
1131 PM CST THU DEC 13 2012
AT 05Z HIGH PRESSURE WAS CENTERED OVER CENTRAL MINNESOTA...WHERE
SKIES WERE CLEAR. FOG AND SOME STRATUS HAD FORMED ON THE SOUTHERN
EDGE OF THE HIGH FROM CENTRAL MINNESOTA INTO NORTH CENTRAL
WISCONSIN. NEAR TERM CONCERNS REMAIN ON FOG/STRATUS POTENTIAL
THROUGH THE OVERNIGHT HOURS. 14.03Z RAP SOUNDINGS CONTINUE TO
INDICATE LOW LEVEL SATURATION REMAINS NORTH OF THE TAF SITES AND
THUS EXPECT THE LOWEST VISIBILITIES IN THESE AREAS. 14.00Z NAM HAS
ALSO BACKED AWAY FROM THE BOUNDARY LAYER SATURATION AT KLSE AND
KRST. GIVEN CURRENT TEMPERATURES/DEW POINT SPREADS OF 2 TO 3
DEGREES AT KLSE AND KRST DO FEEL SOME FOG IS LIKELY AT THE TAF
SITES...MAINLY IN THE MVFR CATEGORY AND WILL USE A TEMPO GROUP FOR
IFR CONDITIONS BETWEEN 08Z-12Z. PRESSURE GRADIENT DOES TIGHTEN BY
MID MORNING AND SHOULD SCOUR OUT ANY REMAINING STRATUS AND FOG
WITH VFR CONDITIONS THROUGH AT LEAST 02Z. BETWEEN 02Z-06Z AN AREA
OF LOW PRESSURE WILL LIFT OUT OF THE PLAINS TOWARDS THE AREA. AT
THIS TIME IT LOOKS LIKE ANY PRECIPITATION AT THE SITES WILL BE
AFTER 06Z...WITH JUST LOWERING CEILINGS IN THE 02Z-06Z TIME
FRAME...POSSIBLY INTO MVFR BY 06Z.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
323 PM CST THU DEC 13 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...DTJ
LONG TERM....DTJ
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
412 AM MST FRI DEC 14 2012
.SHORT TERM...AN UPPER LEVEL TROUGH OVER THE SWRN US WILL EJECT
QUICKLY ACROSS THE AREA THIS AFTN THRU THE EARLY EVENING HOURS. QG
FIELDS SHOW SOME MID LVL ASCENT AS SYSTEM MOVES ACROSS ALTHOUGH
WITH LAPSE RATES AROUND 6 C/KM. OVERALL FLOW IN THE MTNS WILL BE
SLY THRU THE AFTN AND THEN BECOME MORE WNW THIS EVENING AS THE
UPPER LEVEL TROUGH PASSES. THUS SHOULD SEE SOME SNOW ESPECIALLY
AS OROGRAPHIC COMPONENT BECOMES BETTER BY EARLY THIS EVENING WITH
SOME LIGHT ACCUMULATIONS. OVER NERN CO SFC LOW PRESSURE WILL
DEVELOP OVER THE AREA TODAY AND THEN MOVE INTO THE CNTRL PLAINS BY
TONIGHT. OVERALL SFC PTRN IS NOT REAL FAVORABLE FOR PCPN HOWEVER
WITH INCREASING MOISTURE AND MID LVL ASCENT WITH UPPER LEVEL
TROUGH WILL SEE A CHC OF PCPN MOSTLY OVER THE PLAINS. THE RAP
MODEL KEEPS A CHC OF PCPN CLOSER TO THE FOOTHILLS IN THE AFTN
WHILE ALL OF THE OTHER MODELS ARE CONSIDERABLY DRIER. FOR NOW WILL
JUST MENTION A SLIGHT CHC OF PCPN AROUND DENVER AND KEEP AREAS
FURTHER NORTH DRY. WET BULB ZEROS WOULD SUGGEST A MIXTURE OF RAIN
AND SNOW AT LOWER ELEVATIONS THIS AFTN WITH A MAINLY SNOW THIS
EVENING. AS FOR HIGHS WITH CONSIDERABLE CLOUD COVER AND SOME
COLLING OCCURRING IN THE LOWER LEVELS WILL KEEP HIGHS IN THE LOWER
TO MID 40S ACROSS NERN CO.
FOR TONIGHT THE UPPER LEVEL TROUGH WILL MOVE QUICKLY EAST OF THE
AREA WITH SOME LINGERING SNOW OVER THE FAR NERN PLAINS THROUGH
MIDNIGHT BEFORE ENDING. IN THE MTNS WILL CONTINUE TO SEE SOME
OROGRAPHIC SNOW OVERNIGHT.
.LONG TERM...FIRST IN A SERIES OF SHORTWAVE TROUGHS WHISKED ALONG BY
A MODERATELY STRONG WESTERLY FLOW ALOFT SHOULD BE WELL EAST OF THE
STATE BY SATURDAY MORNING. WEST-NORTHWESTERLY LOW-LEVEL FLOW DURING
THE MORNING HOURS AIDS IN DRYING THE BOUNDARY LAYER EAST OF THE
MTNS. SHOULD SEE A FAIR AMOUNT OF SUNSHINE TO START THE DAY BEFORE
THE RETURN OF MOSTLY CLOUDY SKIES IN THE AFTERNOON AS THE NEXT IN
THE SERIES OF SHORTWAVE TROUGH WHICH MODELS SHOW TRAVERSING THE
STATE LATE SATURDAY AFTERNOON AND OVERNIGHT. THIS WAVE APPEARS TO DE-
AMPLIFY SOME AS IT PASSES OVER THE AREA SATURDAY EVENING. AS THIS IS
GOING ON...MODELS ALSO SHOW A WEAK COLD FRONT BACKING INTO NERN
COLORADO WHICH CAUSES W-NWLY SFC WINDS TO TURN N-NELY FOR SEVERAL
HOURS IN THE EVENING. MODELS...PARTICULARLY THE GFS...SHOW A BAND OF
LIGHT PCPN FORMING ALONG THIS FRONTAL BOUNDARY AS IT SLIPS S-
SWWRD...POSSIBLY AS FAR WEST AS EASTERN PORTIONS OF THE DENVER METRO
AREA BY ERLY IN THE EVENING. SHWRS UP ALONG THE WYOMING BORDER IN
THE AFTERNOON SHOULD START OUT AS RAIN WITH TEMPS IN THE 40S. THEN
AS TEMPS FALL AND SHOWERS BECOME A BIT MORE NUMEROUS FARTHER
SOUTH...PCPN IS EXPECTED TO CHANGE TO A RAIN/SNOW MIX IN THE
EVENING. COULD SEE A FEW POCKETS OF VERY LIGHT SNOW ACCUMULATION
WELL EAST OF THE I-25 CORRIDOR...BUT OVERALL NOT LOOKING FOR ANY
ACCUMULATION ON THE PLAINS. IN THE HIGH COUNTRY...SCATTERED TO
LIKELY POPS ARE IN ORDER THROUGHOUT THE DAY...WITH THE BEST CHANCE
FOR MEASURABLE SNOW ONCE AGAIN ALONG AND WEST OF THE CONTINENTAL
DIVIDE DUE TO THE WESTERLY FLOW AT MTN TOP LEVEL. THIS SYSTEM DOES
NOT LOOK LIKE A BIG SNOW PRODUCER FOR OUR PART OF THE
STATE...PROBABLY NO MORE THAN 3-4 INCHES AT BEST ON WINDWARD SLOPES
AND PERHAPS AN INCH OR SO ON THE VALLEY FLOORS BY LATE SATURDAY
EVENING.
ANOTHER UPPER AIR SYSTEM...THOUGH NOT AS STRONG AS ITS TWO
PREDECESSORS...DROPS IN FROM IDAHO/NRN UTAH DURING THE DAY SUNDAY
BRINGS YET ANOTHER SHOT OF SNOWFALL TO THE NORTH-CENTRAL MOUNTAINS
BY SUNDAY AFTERNOON AND EVENING...AND POSSIBLY A FEW RAIN/SNOW
SHOWERS TO THE NERN CORNER OF THE STATE BY EVENING. AGAIN...
NORTHWEST FACING MTN SLOPES COULD PICK UP ANOTHER FEW INCHES OF
SNOW...WITH PERHAPS AN INCH OF SNOW ON VALLEY FLOORS... AND NO
ACCUMULATION ON THE PLAINS. THIS WEATHER MAKER IS FORECAST TO
QUICKLY MOVE OUT BY MONDAY MORNING AS A STRONG HIGH PRESSURE RIDGE
BUILDS IN OVER THE GREAT BASIN. THIS RIDGE MOVES EAST ON MONDAY AND
TRAVERSES THE STATE ON TUESDAY PRODUCING PROBABLY THE WARMEST
TEMPERATURES OF THE WEEK ALONG WITH A DECENT AMOUNT OF
SUNSHINE...ESPLY EAST OF THE MTNS. BY WEDNESDAY...MEDIUM RANGE
MODELS SHOW YET ANOTHER TROUGH SWINGING ACROSS THE REGION FROM THE
CENTRAL GREAT BASIN...POTENTIALLY BRINGING MORE SNOW TO THE HIGH
COUNTRY AND POSSIBLY A FEW RAIN SHOWERS TO LOWER ELEVATIONS.
&&
.AVIATION...RAP SHOWS A CHC OF A RAIN/SNOW SHOWERS THIS AFTN WHILE THE
NAM AND GFS KEEP MOST OF THE ACTIVITY EAST OF THE AIRPORT. FOR
NOW WILL JUST MENTION VCTY IN THE TAF. WILL HAVE CONSIDERABLE MID
AND HIGH LVL CLOUDS THRU THE DAY WITH CEILINGS LOWERING TO 8000 FT
BY EARLY AFTN. THE NAM AND RAP HAVE LOWER CEILINGS DOWN TO 5000 FT
OR SO BY AFTN BUT WILL KEEP THEM AROUND 8000 FT FOR NOW. AS FOR
WINDS A SFC LOW HS FORMED EARLY THIS MORNING NR DENVER WITH LIGHT
WLY WINDS AT THE AIRPORT. THE LATEST RAP KEEPS THIS LOW NR DENVER
THRU AFTN WITH VARIABLE WIND DIRECTIONS. FOR NOW WILL HAVE THEM
TRENDING LIGHT ELY BY LATE MORNING THRU MID AFTN AND THEN BECOMING
MORE NLY BY 00Z. BY EARLY EVENING WILL HAVE NWLY WINDS FOR A FEW
HOURS AND THEN MORE WSW BY 06Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....BAKER
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
359 AM MST FRI DEC 14 2012
.SHORT TERM...SOUTHWEST FLOW ALOFT WILL KEEP RELATIVELY MILD
TEMPERATURES IN PLACE OVERNIGHT. CLOUDS WILL BEGIN TO INCREASE AND
THICKEN LATE TONIGHT AS UPPER LEVEL MOISTURE FROM NEXT UPPER
TROUGH MOVES THIS WAY. THIS UPPER LEVEL TROUGH KICKS RATHER
QUICKLY EASTWARD FROM CALIFORNIA INTO THE DESERT SOUTHWEST LATE
TONIGHT INTO EARLY FRIDAY MORNING. THE MAIN PIECE OF ENERGY THEN
SHIFTS QUICKLY NORTHEAST ACROSS THE EASTERN PLAINS OF COLORADO BY
FRIDAY AFTERNOON. WHILE MOST OF THE CWA WILL HAVE UPWARD Q-G
VERTICAL MOTION...THE DEEPEST MOISTURE IS STILL ADVERTISED TO PUSH
ACROSS THE EASTERN PLAINS. AS A RESULT...WILL BUMP UP POPS A BIT
MORE IN THE LIMON-AKRON-JULESBURG AREAS WHILE KEEPING MAINLY DRY
CONDITIONS IN THE I-25 CORRIDOR FROM DENVER TO THE WYOMING BORDER.
CANT RULE OUT A LITTLE SNOW MIXED IN AT TIMES ON THE PLAINS BUT
NO APPRECIABLE ACCUMULATION EXPECTED WITH SURFACE TEMPS HOLDING
ABOVE FREEZING AND GENERALLY LIGHT QPF OF 0.10 INCH OR LESS. THE
MOUNTAINS MAY ALSO BE ON THE NORTHERN EDGE OF THE MOISTURE BUT
GIVEN ELEVATION WILL KEEP MODEST POPS IN PLACE THERE...ESPECIALLY
FROM I-70 CORRIDOR SOUTHWARD.
.LONG TERM...FIRST IN A SERIES OF SHORTWAVE TROUGHS WHISKED ALONG BY
A MODERATELY STRONG WESTERLY FLOW ALOFT SHOULD BE WELL EAST OF THE
STATE BY SATURDAY MORNING. WEST-NORTHWESTERLY LOW-LEVEL FLOW DURING
THE MORNING HOURS AIDS IN DRYING THE BOUNDARY LAYER EAST OF THE
MTNS. SHOULD SEE A FAIR AMOUNT OF SUNSHINE TO START THE DAY BEFORE
THE RETURN OF MOSTLY CLOUDY SKIES IN THE AFTERNOON AS THE NEXT IN
THE SERIES OF SHORTWAVE TROUGH WHICH MODELS SHOW TRAVERSING THE
STATE LATE SATURDAY AFTERNOON AND OVERNIGHT. THIS WAVE APPEARS TO DE-
AMPLIFY SOME AS IT PASSES OVER THE AREA SATURDAY EVENING. AS THIS IS
GOING ON...MODELS ALSO SHOW A WEAK COLD FRONT BACKING INTO NERN
COLORADO WHICH CAUSES W-NWLY SFC WINDS TO TURN N-NELY FOR SEVERAL
HOURS IN THE EVENING. MODELS...PARTICULARLY THE GFS...SHOW A BAND OF
LIGHT PCPN FORMING ALONG THIS FRONTAL BOUNDARY AS IT SLIPS S-
SWWRD...POSSIBLY AS FAR WEST AS EASTERN PORTIONS OF THE DENVER METRO
AREA BY ERLY IN THE EVENING. SHWRS UP ALONG THE WYOMING BORDER IN
THE AFTERNOON SHOULD START OUT AS RAIN WITH TEMPS IN THE 40S. THEN
AS TEMPS FALL AND SHOWERS BECOME A BIT MORE NUMEROUS FARTHER
SOUTH...PCPN IS EXPECTED TO CHANGE TO A RAIN/SNOW MIX IN THE
EVENING. COULD SEE A FEW POCKETS OF VERY LIGHT SNOW ACCUMULATION
WELL EAST OF THE I-25 CORRIDOR...BUT OVERALL NOT LOOKING FOR ANY
ACCUMULATION ON THE PLAINS. IN THE HIGH COUNTRY...SCATTERED TO
LIKELY POPS ARE IN ORDER THROUGHOUT THE DAY...WITH THE BEST CHANCE
FOR MEASURABLE SNOW ONCE AGAIN ALONG AND WEST OF THE CONTINENTAL
DIVIDE DUE TO THE WESTERLY FLOW AT MTN TOP LEVEL. THIS SYSTEM DOES
NOT LOOK LIKE A BIG SNOW PRODUCER FOR OUR PART OF THE
STATE...PROBABLY NO MORE THAN 3-4 INCHES AT BEST ON WINDWARD SLOPES
AND PERHAPS AN INCH OR SO ON THE VALLEY FLOORS BY LATE SATURDAY
EVENING.
ANOTHER UPPER AIR SYSTEM...THOUGH NOT AS STRONG AS ITS TWO
PREDECESSORS...DROPS IN FROM IDAHO/NRN UTAH DURING THE DAY SUNDAY
BRINGS YET ANOTHER SHOT OF SNOWFALL TO THE NORTH-CENTRAL MOUNTAINS
BY SUNDAY AFTERNOON AND EVENING...AND POSSIBLY A FEW RAIN/SNOW
SHOWERS TO THE NERN CORNER OF THE STATE BY EVENING. AGAIN...
NORTHWEST FACING MTN SLOPES COULD PICK UP ANOTHER FEW INCHES OF
SNOW...WITH PERHAPS AN INCH OF SNOW ON VALLEY FLOORS... AND NO
ACCUMULATION ON THE PLAINS. THIS WEATHER MAKER IS FORECAST TO
QUICKLY MOVE OUT BY MONDAY MORNING AS A STRONG HIGH PRESSURE RIDGE
BUILDS IN OVER THE GREAT BASIN. THIS RIDGE MOVES EAST ON MONDAY AND
TRAVERSES THE STATE ON TUESDAY PRODUCING PROBABLY THE WARMEST
TEMPERATURES OF THE WEEK ALONG WITH A DECENT AMOUNT OF
SUNSHINE...ESPLY EAST OF THE MTNS. BY WEDNESDAY...MEDIUM RANGE
MODELS SHOW YET ANOTHER TROUGH SWINGING ACROSS THE REGION FROM THE
CENTRAL GREAT BASIN...POTENTIALLY BRINGING MORE SNOW TO THE HIGH
COUNTRY AND POSSIBLY A FEW RAIN SHOWERS TO LOWER ELEVATIONS.
&&
.AVIATION...RAP SHOWS A CHC OF A RAIN/SNOW SHOWERS THIS AFTN WHILE
THE NAM AND GFS KEEP MOST OF THE ACTIVITY EAST OF THE AIRPORT. FOR
NOW WILL JUST MENTION VCTY IN THE TAF. WILL HAVE CONSIDERABLE MID
AND HIGH LVL CLOUDS THRU THE DAY WITH CEILINGS LOWERING TO 8000 FT
BY EARLY AFTN. THE NAM AND RAP HAVE LOWER CEILINGS DOWN TO 5000 FT
OR SO BY AFTN BUT WILL KEEP THEM AROUND 8000 FT FOR NOW. AS FOR
WINDS A SFC LOW HS FORMED EARLY THIS MORNING NR DENVER WITH LIGHT
WLY WINDS AT THE AIRPORT. THE LATEST RAP KEEPS THIS LOW NR DENVER
THRU AFTN WITH VARIABLE WIND DIRECTIONS. FOR NOW WILL HAVE THEM
TRENDING LIGHT ELY BY LATE MORNING THRU MID AFTN AND THEN BECOMING
MORE NLY BY 00Z. BY EARLY EVENING WILL HAVE NWLY WINDS FOR A FEW
HOURS AND THEN MORE WSW BY 06Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES... NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....BAKER
AVIATION...RPK
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER/BOULDER CO
312 PM MST THU DEC 13 2012
.SHORT TERM...SOUTHWEST FLOW ALOFT WILL KEEP RELATIVELY MILD
TEMPERATURES IN PLACE OVERNIGHT. CLOUDS WILL BEGIN TO INCREASE AND
THICKEN LATE TONIGHT AS UPPER LEVEL MOISTURE FROM NEXT UPPER
TROUGH MOVES THIS WAY. THIS UPPER LEVEL TROUGH KICKS RATHER
QUICKLY EASTWARD FROM CALIFORNIA INTO THE DESERT SOUTHWEST LATE
TONIGHT INTO EARLY FRIDAY MORNING. THE MAIN PIECE OF ENERGY THEN
SHIFTS QUICKLY NORTHEAST ACROSS THE EASTERN PLAINS OF COLORADO BY
FRIDAY AFTERNOON. WHILE MOST OF THE CWA WILL HAVE UPWARD Q-G
VERTICAL MOTION...THE DEEPEST MOISTURE IS STILL ADVERTISED TO PUSH
ACROSS THE EASTERN PLAINS. AS A RESULT...WILL BUMP UP POPS A BIT
MORE IN THE LIMON-AKRON-JULESBURG AREAS WHILE KEEPING MAINLY DRY
CONDITIONS IN THE I-25 CORRIDOR FROM DENVER TO THE WYOMING BORDER.
CANT RULE OUT A LITTLE SNOW MIXED IN AT TIMES ON THE PLAINS BUT
NO APPRECIABLE ACCUMULATION EXPECTED WITH SURFACE TEMPS HOLDING
ABOVE FREEZING AND GENERALLY LIGHT QPF OF 0.10 INCH OR LESS. THE
MOUNTAINS MAY ALSO BE ON THE NORTHERN EDGE OF THE MOISTURE BUT
GIVEN ELEVATION WILL KEEP MODEST POPS IN PLACE THERE...ESPECIALLY
FROM I-70 CORRIDOR SOUTHWARD.
.LONG TERM...FIRST IN A SERIES OF SHORTWAVE TROUGHS WHISKED ALONG BY
A MODERATELY STRONG WESTERLY FLOW ALOFT SHOULD BE WELL EAST OF THE
STATE BY SATURDAY MORNING. WEST-NORTHWESTERLY LOW-LEVEL FLOW DURING
THE MORNING HOURS AIDS IN DRYING THE BOUNDARY LAYER EAST OF THE
MTNS. SHOULD SEE A FAIR AMOUNT OF SUNSHINE TO START THE DAY BEFORE
THE RETURN OF MOSTLY CLOUDY SKIES IN THE AFTERNOON AS THE NEXT IN
THE SERIES OF SHORTWAVE TROUGH WHICH MODELS SHOW TRAVERSING THE
STATE LATE SATURDAY AFTERNOON AND OVERNIGHT. THIS WAVE APPEARS TO DE-
AMPLIFY SOME AS IT PASSES OVER THE AREA SATURDAY EVENING. AS THIS IS
GOING ON...MODELS ALSO SHOW A WEAK COLD FRONT BACKING INTO NERN
COLORADO WHICH CAUSES W-NWLY SFC WINDS TO TURN N-NELY FOR SEVERAL
HOURS IN THE EVENING. MODELS...PARTICULARLY THE GFS...SHOW A BAND OF
LIGHT PCPN FORMING ALONG THIS FRONTAL BOUNDARY AS IT SLIPS S-
SWWRD...POSSIBLY AS FAR WEST AS EASTERN PORTIONS OF THE DENVER METRO
AREA BY ERLY IN THE EVENING. SHWRS UP ALONG THE WYOMING BORDER IN
THE AFTERNOON SHOULD START OUT AS RAIN WITH TEMPS IN THE 40S. THEN
AS TEMPS FALL AND SHOWERS BECOME A BIT MORE NUMEROUS FARTHER
SOUTH...PCPN IS EXPECTED TO CHANGE TO A RAIN/SNOW MIX IN THE
EVENING. COULD SEE A FEW POCKETS OF VERY LIGHT SNOW ACCUMULATION
WELL EAST OF THE I-25 CORRIDOR...BUT OVERALL NOT LOOKING FOR ANY
ACCUMULATION ON THE PLAINS. IN THE HIGH COUNTRY...SCATTERED TO
LIKELY POPS ARE IN ORDER THROUGHOUT THE DAY...WITH THE BEST CHANCE
FOR MEASURABLE SNOW ONCE AGAIN ALONG AND WEST OF THE CONTINENTAL
DIVIDE DUE TO THE WESTERLY FLOW AT MTN TOP LEVEL. THIS SYSTEM DOES
NOT LOOK LIKE A BIG SNOW PRODUCER FOR OUR PART OF THE
STATE...PROBABLY NO MORE THAN 3-4 INCHES AT BEST ON WINDWARD SLOPES
AND PERHAPS AN INCH OR SO ON THE VALLEY FLOORS BY LATE SATURDAY
EVENING.
ANOTHER UPPER AIR SYSTEM...THOUGH NOT AS STRONG AS ITS TWO
PREDECESSORS...DROPS IN FROM IDAHO/NRN UTAH DURING THE DAY SUNDAY
BRINGS YET ANOTHER SHOT OF SNOWFALL TO THE NORTH-CENTRAL MOUNTAINS
BY SUNDAY AFTERNOON AND EVENING...AND POSSIBLY A FEW RAIN/SNOW
SHOWERS TO THE NERN CORNER OF THE STATE BY EVENING. AGAIN...
NORTHWEST FACING MTN SLOPES COULD PICK UP ANOTHER FEW INCHES OF
SNOW...WITH PERHAPS AN INCH OF SNOW ON VALLEY FLOORS... AND NO
ACCUMULATION ON THE PLAINS. THIS WEATHER MAKER IS FORECAST TO
QUICKLY MOVE OUT BY MONDAY MORNING AS A STRONG HIGH PRESSURE RIDGE
BUILDS IN OVER THE GREAT BASIN. THIS RIDGE MOVES EAST ON MONDAY AND
TRAVERSES THE STATE ON TUESDAY PRODUCING PROBABLY THE WARMEST
TEMPERATURES OF THE WEEK ALONG WITH A DECENT AMOUNT OF
SUNSHINE...ESPLY EAST OF THE MTNS. BY WEDNESDAY...MEDIUM RANGE
MODELS SHOW YET ANOTHER TROUGH SWINGING ACROSS THE REGION FROM THE
CENTRAL GREAT BASIN...POTENTIALLY BRINGING MORE SNOW TO THE HIGH
COUNTRY AND POSSIBLY A FEW RAIN SHOWERS TO LOWER ELEVATIONS.
&&
.AVIATION...RAP SHOWS A CHC OF A RAIN/SNOW SHOWERS THIS AFTN WHILE
THE NAM AND GFS KEEP MOST OF THE ACTIVITY EAST OF THE AIRPORT. FOR
NOW WILL JUST MENTION VCTY IN THE TAF. WILL HAVE CONSIDERABLE MID
AND HIGH LVL CLOUDS THRU THE DAY WITH CEILINGS LOWERING TO 8000 FT
BY EARLY AFTN. THE NAM AND RAP HAVE LOWER CEILINGS DOWN TO 5000 FT
OR SO BY AFTN BUT WILL KEEP THEM AROUND 8000 FT FOR NOW. AS FOR
WINDS A SFC LOW HS FORMED EARLY THIS MORNING NR DENVER WITH LIGHT
WLY WINDS AT THE AIRPORT. THE LATEST RAP KEEPS THIS LOW NR DENVER
THRU AFTN WITH VARIABLE WIND DIRECTIONS. FOR NOW WILL HAVE THEM
TRENDING LIGHT ELY BY LATE MORNING THRU MID AFTN AND THEN BECOMING
MORE NLY BY 00Z. BY EARLY EVENING WILL HAVE NWLY WINDS FOR A FEW
HOURS AND THEN MORE WSW BY 06Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES... NONE.
&&
$$
SHORT TERM...RPK
LONG TERM....BAKER
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS GOODLAND KS
448 AM MST FRI DEC 14 2012
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 342 AM MST FRI DEC 14 2012
MAIN FORECAST CONCERN WILL BE STORM SYSTEM THAT WILL IMPACT THE AREA
THROUGH TONIGHT. SATELLITE SHOWING A PROGRESSIVE NEARLY ZONAL FLOW
FROM THE PACIFIC INTO THE WESTERN ATLANTIC. THE EXCEPTION TO THIS
IS THE SYSTEM THAT IS CUT OFF FROM THE FLOW AND EXTENDS FROM NEVADA
TO JUST OFF THE SOUTHERN CALIFORNIA COAST. THROUGH 05Z THIS SYSTEM
WAS STILL DIGGING AND NOT MAKING ANY PROGRESS EAST YET. THIS TROUGH
HAS PULLED UP SUBTROPICAL MOISTURE AHEAD OF IT.
AT JET LEVEL...THE NAM...UKMET AND SREF LOOK TO HAVE THE JET SEGMENT
COMING IN FROM THE SOUTHWEST THE BEST. OTHER MODELS TENDED TO HAVE
THE HIGHER SPEEDS TOO FAR NORTH OR EAST. AT MID LEVELS...WITH THE
INCOMING UPPER TROUGH...MODELS TENDED TO BE TOO FAR SOUTH AND EAST.
THE GFS AND CANADIAN WERE DOING A LITTLE BETTER THAN THE SREF AND
NAM. MODELS ALSO TENDED TO BE TOO GENEROUS WITH THE MID LEVEL
MOISTURE. MODELS ARE HAVING A HARD CATCHING THE SUBTLE COLD FRONT
THAT SAGGED OVER THE AREA TODAY. THE NAM AND RUC WERE DOING THE
BEST. ALSO MODELS ARE TOO GENEROUS WITH LOW LEVEL MOISTURE WITH THE
HIGHER DEWPOINTS TOO FAR NORTH ALREADY. THE GFS AND CANADIAN WERE
DOING THE BEST ON THE LOW LEVEL THERMAL FIELD.
TODAY/TONIGHT...LEFT FRONT QUADRANT OF THE JET CONTINUES TO MOVE
CLOSE TO AREA AND AFFECTS THE AREA MAINLY FROM 12Z TO 18Z. DURING
THAT TIME IT LOOKS LIKE THERE IS NOT A LOT OF LOW LEVEL MOISTURE BUT
LITTLE MOISTURE IN THE COLUMN. SURFACE OBSERVATIONS AND 00Z SOUNDINGS
TO OUR SOUTH ARE VERY DRY. BY THE TIME THE MOISTURE GETS HERE...THE
MAIN JET IS WELL EAST. SPEAKING OF MOISTURE RETURN...DEWPOINTS
REMAIN VERY LOW AND THERE IS NO SIGNIFICANT INCREASE IN MOISTURE
UNTIL WELL SOUTH. MODELS ARE OVERDOING MOISTURE RETURN RIGHT NOW.
00Z SOUNDINGS OVER OUR AREA AND TO THE SOUTH ARE EXTREMELY DRY.
MOISTURE TRAJECTORIES WOULD SUPPORT BEST MOISTURE FURTHER SOUTH AND
EAST. ALSO THUNDERSTORMS WILL BE DEVELOPING TO OUR SOUTH AND EAST
AND SLOW DOWN OR ROB ANY MOISTURE RETURN WE WERE GOING TO SEE.
DUE TO THE SUBTROPICAL MOISTURE RETURN...THERE LOOKS TO BE A
SIGNIFICANT MID/UPPER LEVEL CLOUD DECK WHICH WILL INHIBIT HEATING
AND ANY SURFACE INSTABILITY. MODELS ARE ALSO SHOWING LITTLE TO NO
ELEVATED CAPE AS WELL. WITH MODELS OVERDOING THE INFLUX OF MOISTURE
MODELS ARE PROBABLY OVERDOING ANY INSTABILITY AS WELL. SO CHOSE TO
KEEP THUNDER OUT OF THE FORECAST.
00Z MODEL DATA WAS HINTING AT IT AND NOW 06Z IS CATCHING ONTO IT
EVEN MORE. THE MODELS STILL BRING THE SYSTEM ACROSS IN A NEGATIVE
TILT. HOWEVER...THEY BRING IT ACROSS WITH A NORTHERN AND SOUTHERN
CIRCULATION ON EITHER SIDE OF THE FORECAST AREA. MODELS HAVE BACKED
THEIR IDEA OF ANY WRAP AROUND ON THE BACKSIDE OF THE SYSTEM. PLUS
MODELS HAVE PUSHED EASTERN BAND OF PRECIPITATION FURTHER SOUTH AND
EAST. SO IN A NUTSHELL BEST MOISTURE...LIFT...AND INSTABILITY ARE
NOT INSYNC OR NOT THERE. AT THIS TIME IT STILL DOES LOOK LIKE THE
NORTHEAST PORTION OF THE AREA WILL HAVE THE BEST CHANCE FOR
MEASURABLE PRECIPITATION WITH LITTLE TO NONE FURTHER SOUTHWEST AND
WEST YOU GO.
NEW MODEL GUIDANCE SLOWED THINGS DOWN ON PRECIPITATION ARRIVAL AND
LIMITED POPS TO THE AFTERNOON AND TIERED THEM FROM LOWEST TO HIGHEST
PER REASONING ABOVE. BELIEVE PRECIPITATION WILL SHUT OFF PRETTY QUICK
GIVEN THE SPEED OF THE SYSTEM AND MODEL DEFICIENCIES MENTIONED
ABOVE. BELIEVE MOST OF THE PRECIPITATION WILL BE DOWN BY OR SHORTLY
AFTER 06Z. DID HOLD ONTO PRECIPITATION AFTER THAT JUST KEEP WITHIN
SOME CLOSENESS WITH MY NEIGHBORS. IN REGARDS TO PHASE. LOOKS LIKE IT
STAYS RAIN THROUGH THE DAY. MODEL SOUNDINGS INDICATE TEMPERATURES
STAYING ABOVE FREEZING FOR MOST OF THE NIGHT EVEN IF THERE IS ICE IN
THE COLUMN. SOUNDINGS ARE ALSO NOT OPTIMISTIC ABOUT ICE IN THE
COLUMN EITHER. IT ALSO LOOKS BY THE TIME THE AIR MASS GETS COLD
ENOUGH TO SUPPORT SNOW...THE LIFT AND MOISTURE ARE GONE. SO ONLY
HAVE A MIX OF RAIN AND SNOW AT BEST. THEREFORE THERE SHOULD BE
LITTLE TO NO SNOW ACCUMULATION.
PRIOR TO ARRIVAL OF CLOUDS TEMPERATURES HAVE COOLED OFF
DRAMATICALLY THIS MORNING WITH MODELS TOO WARM. COMBINATION OF
UNFAVORABLE WIND FIELD AND INCREASING CLOUD COVER/DEVELOPING
PRECIPITATION WILL KEEP TEMPERATURES FROM WARMING MUCH. BELIEVE THE
GEM WAS CATCHING THE IDEA THE BEST AND I MAY BE TOO WARM.
SATURDAY/SATURDAY NIGHT...TRICKY MAX TEMPERATURE FORECAST. NORTHWEST
WINDS AND SOME SUN EARLY WILL ALLOW FOR TEMPERATURES TO WARM. BUT
NEXT SHORTWAVE TROUGH WILL DRAMATICALLY INCREASE CLOUD COVER IN THE
AFTERNOON. CHOSE TO TOWARD THE COOLER SIDE. FOR THE NIGHT MODELS
STILL PRODUCING QPF. MODELS DIFFER ON WHERE TO PUT IT BUT GENERALLY
FAVOR THE SOUTHWEST. NOT UNREASONABLE FOR PRECIPITATION TO OCCUR
ANYWHERE BUT AM NOT TOTALLY SOLD ON ANYTHING OCCURRING. SO
BROADBRUSHED LOW SLIGHT CHANCE POPS FOR THE ENTIRE AREA.
SUNDAY/SUNDAY NIGHT...AGAIN LIGHT WIND FIELD AND INCREASING CLOUD
COVER WILL CREATE FOR A TRICKY HIGH TEMPERATURE FORECAST. MODELS
INDICATE A COOLER AIR MASS THAN ON SATURDAY. TRENDED COOLER OR
TOWARD COOLER GUIDANCE.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 342 AM MST FRI DEC 14 2012
AN UPPER LEVEL RIDGE WILL MOVE OVER THE AREA THE FIRST PART OF NEXT
WEEK. FOLLOWING THE RIDGE WILL BE A SHORT WAVE TROUGH...WHICH WILL
APPROACH THE AREA WEDNESDAY. AHEAD OF THE TROUGH THERE MAY BE A
CHANCE FOR SOME PRECIPITATION WEDNESDAY AS A COLD FRONT MOVES
THROUGH. AT THIS TIME MODELS DISAGREE WITH THE TIMING OF THE FRONT
BY AS MUCH AS 12 HOURS. IN ADDITION...LIFT ALONG THE FRONT DOES NOT
LOOK STRONG ENOUGH AT THIS POINT TO DEVELOP ANY PRECIPITATION AND
THE ENVIRONMENT MOISTENS BEHIND THE FRONT WHERE THERE IS ALMOST NO
LIFT. IF MODELS COME INTO A BETTER AGREEMENT WITH THE FRONTAL
PASSAGE...AND IF THE LIFT ALONG THE FRONT WILL STRENGTHEN WITH A
BETTER SUPPLY OF MOISTURE...A MENTION OF PRECIPITATION WILL THEN BE
WARRANTED.
TEMPERATURES FOR THE PERIOD WILL WARM THROUGH WEDNESDAY AHEAD OF THE
COLD FRONT...WITH VALUES 10 TO 15 DEGREES ABOVE NORMAL. AFTER THE
COLD FRONT TEMPERATURES RETURN TO NEAR NORMAL VALUES.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 441 AM MST FRI DEC 14 2012
VERY TRICKY TAF FORECAST. DETAILS DIFFER AMONG THE MODEL OUTPUT AS
TO THE ONSET OF PRECIPITATION AND ALSO WHERE/HOW FAST TO BRING IN
LOWER CEILINGS. AT THIS TIME IT DOES LOOK LIKE RAINFALL WILL NOT
DEVELOP UNTIL MID TO LATE AFTERNOON AT BOTH SITES AND THEN CONTINUE
INTO THE MIDDLE OF THE NIGHT. KMCK WILL HAVE THE BEST CHANCE FOR
RAINFALL WITH ONLY A MINOR REDUCTION IN VISIBILITY. FOR
KGLD...MVFR CEILINGS ARE EXPECTED FROM LATE AFTERNOON UNTIL LATE
EVENING. AT THAT TIME...A COLD FRONT WILL MOVE THROUGH AND ALLOW
CEILINGS TO BECOME VFR. FOR KMCK...MVFR CEILINGS WILL LOWER TO
IFR/LIFR BY MID EVENING ALONG WITH MVFR VISIBILITIES IN FOG AND
CONTINUE UNTIL THE ABOVE MENTIONED FRONT MOVES THROUGH. AT THAT
TIME CEILINGS SHOULD BECOME MVFR AS THE FOG LIFTS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...BULLER
LONG TERM...JTL
AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
342 AM MST FRI DEC 14 2012
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 342 AM MST FRI DEC 14 2012
MAIN FORECAST CONCERN WILL BE STORM SYSTEM THAT WILL IMPACT THE AREA
THROUGH TONIGHT. SATELLITE SHOWING A PROGRESSIVE NEARLY ZONAL FLOW
FROM THE PACIFIC INTO THE WESTERN ATLANTIC. THE EXCEPTION TO THIS
IS THE SYSTEM THAT IS CUT OFF FROM THE FLOW AND EXTENDS FROM NEVADA
TO JUST OFF THE SOUTHERN CALIFORNIA COAST. THROUGH 05Z THIS SYSTEM
WAS STILL DIGGING AND NOT MAKING ANY PROGRESS EAST YET. THIS TROUGH
HAS PULLED UP SUBTROPICAL MOISTURE AHEAD OF IT.
AT JET LEVEL...THE NAM...UKMET AND SREF LOOK TO HAVE THE JET SEGMENT
COMING IN FROM THE SOUTHWEST THE BEST. OTHER MODELS TENDED TO HAVE
THE HIGHER SPEEDS TOO FAR NORTH OR EAST. AT MID LEVELS...WITH THE
INCOMING UPPER TROUGH...MODELS TENDED TO BE TOO FAR SOUTH AND EAST.
THE GFS AND CANADIAN WERE DOING A LITTLE BETTER THAN THE SREF AND
NAM. MODELS ALSO TENDED TO BE TOO GENEROUS WITH THE MID LEVEL
MOISTURE. MODELS ARE HAVING A HARD CATCHING THE SUBTLE COLD FRONT
THAT SAGGED OVER THE AREA TODAY. THE NAM AND RUC WERE DOING THE
BEST. ALSO MODELS ARE TOO GENEROUS WITH LOW LEVEL MOISTURE WITH THE
HIGHER DEWPOINTS TOO FAR NORTH ALREADY. THE GFS AND CANADIAN WERE
DOING THE BEST ON THE LOW LEVEL THERMAL FIELD.
TODAY/TONIGHT...LEFT FRONT QUADRANT OF THE JET CONTINUES TO MOVE
CLOSE TO AREA AND AFFECTS THE AREA MAINLY FROM 12Z TO 18Z. DURING
THAT TIME IT LOOKS LIKE THERE IS NOT A LOT OF LOW LEVEL MOISTURE BUT
LITTLE MOISTURE IN THE COLUMN. SURFACE OBSERVATIONS AND 00Z SOUNDINGS
TO OUR SOUTH ARE VERY DRY. BY THE TIME THE MOISTURE GETS HERE...THE
MAIN JET IS WELL EAST. SPEAKING OF MOISTURE RETURN...DEWPOINTS
REMAIN VERY LOW AND THERE IS NO SIGNIFICANT INCREASE IN MOISTURE
UNTIL WELL SOUTH. MODELS ARE OVERDOING MOISTURE RETURN RIGHT NOW.
00Z SOUNDINGS OVER OUR AREA AND TO THE SOUTH ARE EXTREMELY DRY.
MOISTURE TRAJECTORIES WOULD SUPPORT BEST MOISTURE FURTHER SOUTH AND
EAST. ALSO THUNDERSTORMS WILL BE DEVELOPING TO OUR SOUTH AND EAST
AND SLOW DOWN OR ROB ANY MOISTURE RETURN WE WERE GOING TO SEE.
DUE TO THE SUBTROPICAL MOISTURE RETURN...THERE LOOKS TO BE A
SIGNIFICANT MID/UPPER LEVEL CLOUD DECK WHICH WILL INHIBIT HEATING
AND ANY SURFACE INSTABILITY. MODELS ARE ALSO SHOWING LITTLE TO NO
ELEVATED CAPE AS WELL. WITH MODELS OVERDOING THE INFLUX OF MOISTURE
MODELS ARE PROBABLY OVERDOING ANY INSTABILITY AS WELL. SO CHOSE TO
KEEP THUNDER OUT OF THE FORECAST.
00Z MODEL DATA WAS HINTING AT IT AND NOW 06Z IS CATCHING ONTO IT
EVEN MORE. THE MODELS STILL BRING THE SYSTEM ACROSS IN A NEGATIVE
TILT. HOWEVER...THEY BRING IT ACROSS WITH A NORTHERN AND SOUTHERN
CIRCULATION ON EITHER SIDE OF THE FORECAST AREA. MODELS HAVE BACKED
THEIR IDEA OF ANY WRAP AROUND ON THE BACKSIDE OF THE SYSTEM. PLUS
MODELS HAVE PUSHED EASTERN BAND OF PRECIPITATION FURTHER SOUTH AND
EAST. SO IN A NUTSHELL BEST MOISTURE...LIFT...AND INSTABILITY ARE
NOT INSYNC OR NOT THERE. AT THIS TIME IT STILL DOES LOOK LIKE THE
NORTHEAST PORTION OF THE AREA WILL HAVE THE BEST CHANCE FOR
MEASURABLE PRECIPITATION WITH LITTLE TO NONE FURTHER SOUTHWEST AND
WEST YOU GO.
NEW MODEL GUIDANCE SLOWED THINGS DOWN ON PRECIPITATION ARRIVAL AND
LIMITED POPS TO THE AFTERNOON AND TIERED THEM FROM LOWEST TO HIGHEST
PER REASONING ABOVE. BELIEVE PRECIPITATION WILL SHUT OFF PRETTY QUICK
GIVEN THE SPEED OF THE SYSTEM AND MODEL DEFICIENCIES MENTIONED
ABOVE. BELIEVE MOST OF THE PRECIPITATION WILL BE DOWN BY OR SHORTLY
AFTER 06Z. DID HOLD ONTO PRECIPITATION AFTER THAT JUST KEEP WITHIN
SOME CLOSENESS WITH MY NEIGHBORS. IN REGARDS TO PHASE. LOOKS LIKE IT
STAYS RAIN THROUGH THE DAY. MODEL SOUNDINGS INDICATE TEMPERATURES
STAYING ABOVE FREEZING FOR MOST OF THE NIGHT EVEN IF THERE IS ICE IN
THE COLUMN. SOUNDINGS ARE ALSO NOT OPTIMISTIC ABOUT ICE IN THE
COLUMN EITHER. IT ALSO LOOKS BY THE TIME THE AIR MASS GETS COLD
ENOUGH TO SUPPORT SNOW...THE LIFT AND MOISTURE ARE GONE. SO ONLY
HAVE A MIX OF RAIN AND SNOW AT BEST. THEREFORE THERE SHOULD BE
LITTLE TO NO SNOW ACCUMULATION.
PRIOR TO ARRIVAL OF CLOUDS TEMPERATURES HAVE COOLED OFF
DRAMATICALLY THIS MORNING WITH MODELS TOO WARM. COMBINATION OF
UNFAVORABLE WIND FIELD AND INCREASING CLOUD COVER/DEVELOPING
PRECIPITATION WILL KEEP TEMPERATURES FROM WARMING MUCH. BELIEVE THE
GEM WAS CATCHING THE IDEA THE BEST AND I MAY BE TOO WARM.
SATURDAY/SATURDAY NIGHT...TRICKY MAX TEMPERATURE FORECAST. NORTHWEST
WINDS AND SOME SUN EARLY WILL ALLOW FOR TEMPERATURES TO WARM. BUT
NEXT SHORTWAVE TROUGH WILL DRAMATICALLY INCREASE CLOUD COVER IN THE
AFTERNOON. CHOSE TO TOWARD THE COOLER SIDE. FOR THE NIGHT MODELS
STILL PRODUCING QPF. MODELS DIFFER ON WHERE TO PUT IT BUT GENERALLY
FAVOR THE SOUTHWEST. NOT UNREASONABLE FOR PRECIPITATION TO OCCUR
ANYWHERE BUT AM NOT TOTALLY SOLD ON ANYTHING OCCURRING. SO
BROADBRUSHED LOW SLIGHT CHANCE POPS FOR THE ENTIRE AREA.
SUNDAY/SUNDAY NIGHT...AGAIN LIGHT WIND FIELD AND INCREASING CLOUD
COVER WILL CREATE FOR A TRICKY HIGH TEMPERATURE FORECAST. MODELS
INDICATE A COOLER AIR MASS THAN ON SATURDAY. TRENDED COOLER OR
TOWARD COOLER GUIDANCE.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 342 AM MST FRI DEC 14 2012
AN UPPER LEVEL RIDGE WILL MOVE OVER THE AREA THE FIRST PART OF NEXT
WEEK. FOLLOWING THE RIDGE WILL BE A SHORT WAVE TROUGH...WHICH WILL
APPROACH THE AREA WEDNESDAY. AHEAD OF THE TROUGH THERE MAY BE A
CHANCE FOR SOME PRECIPITATION WEDNESDAY AS A COLD FRONT MOVES
THROUGH. AT THIS TIME MODELS DISAGREE WITH THE TIMING OF THE FRONT
BY AS MUCH AS 12 HOURS. IN ADDITION...LIFT ALONG THE FRONT DOES NOT
LOOK STRONG ENOUGH AT THIS POINT TO DEVELOP ANY PRECIPITATION AND
THE ENVIRONMENT MOISTENS BEHIND THE FRONT WHERE THERE IS ALMOST NO
LIFT. IF MODELS COME INTO A BETTER AGREEMENT WITH THE FRONTAL
PASSAGE...AND IF THE LIFT ALONG THE FRONT WILL STRENGTHEN WITH A
BETTER SUPPLY OF MOISTURE...A MENTION OF PRECIPITATION WILL THEN BE
WARRANTED.
TEMPERATURES FOR THE PERIOD WILL WARM THROUGH WEDNESDAY AHEAD OF THE
COLD FRONT...WITH VALUES 10 TO 15 DEGREES ABOVE NORMAL. AFTER THE
COLD FRONT TEMPERATURES RETURN TO NEAR NORMAL VALUES.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1000 PM MST THU DEC 13 2012
VFR THROUGH AT LEAST 21Z WITH MVFR/IFR CIGS EXPECTED AFTER 21Z AND
CONTINUING THROUGH THE REST OF THE TAF PERIOD. CIGS WILL QUICKLY
LOWER FRIDAY AFTERNOON...FIRST AT KGLD FOLLOWED SHORTLY BY KMCK AS
A LOW PRESSURE SYSTEM MOVES TOWARD THE AREA FROM THE SOUTHWEST.
A 3 OR SO HOUR PERIOD OF LIGHT RAIN WILL FALL AT KGLD BETWEEN 21
AND 00Z WHILE AT KMCK 22Z-01Z WITHIN AN AREA OF ENHANCED MOISTURE
ROTATING AHEAD OF THE UPPER LOW. ALTHOUGH THE PRECIP ENDS AT BOTH
TERMINALS BY 01Z OR SO PLENTY OF LOW LEVEL MOISTURE REMAINS ACROSS
THE AREA PREVENTING CIGS RISING INTO VFR RANGE. WINDS WILL REMAIN
GENERALLY LIGHT TONIGHT THEN BECOME SOUTHEAST OR SOUTHERLY DURING
THE DAY FRIDAY AROUND 12KTS. AT KGLD A SHIFT TO THE W/NW EXPECTED
AROUND 04Z ON THE BACKSIDE OF THE DEPARTING SYSTEM.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...BULLER
LONG TERM...JTL
AVIATION...DDT
AREA FORECAST DISCUSSION
NWS CARIBOU ME
907 AM EST FRI DEC 14 2012
.SYNOPSIS...
WEAK LOW PRESSURE WILL PASS NORTH OF THE AREA THIS MORNING WITH A
COLD FRONTAL PASSAGE LATER TODAY AND TONIGHT. HIGH PRESSURE BUILDS
NORTH OF THE REGION SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
907 AM UPDATE...THE MAIN UPDATE WAS TO LOWER THE CLOUD COVER A
BIT DOWN TOWARD THE COAST AS SAT PICTS...OBS...AND WEB CAMS
INDICATE P/SUNNY TO M/SUNNY CONDITIONS. ALSO MADE SOME TWEAKS TO
THE WIND GUST GRIDS ACROSS THE COASTAL WATERS TO HOLD OFF WIND
GUSTS TO 25 KT UNTIL THE START TIME OF THE SCA AT 21Z.
OTHERWISE...THE FORECAST LOOKS TO BE IN GOOD SHAPE. STILL EXPECT
SNOW SHOWERS TO DEVELOP ACROSS THE NORTH THIS PM AS A STRONG
ARCTIC COLD FRONT BEGINS TO WORK ACROSS THE AREA.
UPDATE 0625 EST: HAVE ADJUSTED TEMPERATURE...WEATHER AND POPS.
LOW PRESSURE IS CURRENTLY PASSING TO THE NORTH OF THE STATE. A
STRONG COLD FRONT TRAILING THE LOW WILL APPROACH FROM THE WEST
THIS MORNING THE MOVE ACROSS THE STATE DURING THE AFTERNOON.
STRONG COLD ADVECTION BEHIND THE FRONT ALONG WITH AN UPPER TROUGH
WILL RESULT IN UNSTABLE CONDITIONS RESULTING IN SNOW SQUALLS
ESPECIALLY IN THE NORTH DURING THE AFTERNOON INTO THE EVENING.
WILL USE THE RUC13 TO INITIALIZE THE POP GRIDS THROUGH THE MORNING
THEN TRANSITION TO A BLEND OF THE NAM12 ...GFS40 ...SREF AND
ECMWF. FOR QPF WILL ALSO USE SAME MODEL BLEND AND EXCHANGE THE
NAM12 FOR NAM80. FOR SNOW AMOUNTS WILL RUN SNOW FROM THICKNESS
TOOL ON NAM/QPF GRIDS. THE GMOS WAS USED TO INITIALIZE THE
TEMPERATURE AND DEW POINT GRIDS. HAVE MANUALLY ADJUSTED MAXIMUM
AND MINIMUM TEMPERATURES. USED A NAM12/GMOS BLEND FOR WIND SPEED.
FOR WIND GUSTS WILL USE 200 PERCENT OF SUSTAINED SPEED WITH GOOD
MIXING EXPECTED.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
COLDER WEATHER IN STORE FOR THE WEEKEND.
ARCTIC AIR WILL CONTINUE TO PUSH INTO THE CWA ON SATURDAY W/NNW
WINDS ADDING A CHILL TO THE AIR. THIS WILL MEAN SATURDAY`S HIGHS
WILL BE BELOW NORMAL FOR THE IDES OF DECEMBER. A COLD NNW FLOW OFF
THE OPEN ST. LAWRENCE WILL LEAD TO CLOUDS ACROSS NORTHERN 1/2 OF
THE CWA W/SOME FLURRIES OR BANDS OF LIGHT SNOW THROUGH SATURDAY
AFTERNOON. THE NAM AND GFS TEND TO STRUGGLE W/THSI TYPE OF SETUP.
THE CANADIAN GEM LOOKS LIKE IT PICKS UP ON THIS WELL AND DECIDED
TO USE IT TO SET UP THE FORECAST FOR SATURDAY INTO SATURDAY NIGHT.
SKIES WILL GRADUALLY CLEAR ACROSS THE NORTHERN AREAS SATURDAY
NIGHT AS THE FLOW WEAKENS WHILE THE CENTRAL AND DOWNEAST REGION
REMAIN CLEAR. ALL THIS ALLOWING FOR SOME COLD TEMPERATURES BY
EARLY SUNDAY MORNING. STAYED CLOSE TO THE DAYCREW`S ASSESSMENT OF
READINGS AOB 0F ACROSS THE NORTH AND WEST AND IN THE SINGLE
NUMBERS FOR THE CENTRAL AND DOWNEAST REGIONS.
HIGH PRES WILL MOVE ACROSS NORTHERN QUEBEC AND RIDGE DOWN ACROSS
THE REGION ON SUNDAY. AT THE SAME TIME, LOW PRES MOVING ACROSS THE
GREAT LAKES REGION IS FCST TO RE-DEVELOP OFF THE NJ COAST BY
SUNDAY NIGHT. ATTM, DECIDED TO KEEP THE CWA DRY BANKING ON THE
STRONG HIGH TO THE NORTH HOLDING ON LONGER. THIS MATCHES UP WELL
THE LATEST RUNS OF THE NAM/GFS AND ECMWF. WE WILL SEE INCREASING
CLOUDS FROM THE SW DURING THE DAY W/A GRADUAL MODERATION IN
TEMPERATURES BUT STILL BELOW NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THINGS BEGIN TO GET COMPLICATED ESPECIALLY WEDNESDAY INTO
THURSDAY. DETAILS ARE BELOW.
THE 00Z RUNS OF THE ECMWF/OPERATIONAL GFS AND ITS MEAN ENSEMBLE
SUPPORT LOW PRES REDEVELOPING NEAR NJ SUNDAY NIGHT AND THEN SLOWLY
MOVING ENE OFF THE LONG ISLAND COAST. THE GFS IS MOST PROMINENT
W/THIS FEATURE WHILE THE ECWMF AND THE CANADIAN GLOBAL KEEP THE
SYSTEM LESS AMPLIFIED AND SHOW THE HIGH PRES RIDGE HOLDING ON
LONGER KEEPING THE BULK OF THE PRECIP FURTHER S. DECIDED TO BLEND
THE ECMWF AND GFS FOR THIS SYSTEM SUNDAY NIGHT INTO MONDAY. THIS MEANS
CHC POPS SUNDAY NIGHT FOR THE INTERIOR DOWNEAST AND COAST WHICH
MATCHES UP WELL W/GYX AND STAYED DRY FURTHER NORTH GIVEN THE
RIDGE HOLDING IN LONGER.
THE CHALLENGE NOW COMES FOR MONDAY RIGHT INTO LATE WEEK. THE
ECMWF DOES SHOW A MORE SIGNIFICANT LOW MOVING ACROSS THE DELMARVA
ON MONDAY AND LIFTING THROUGH THE GULF OF MAINE LATER TUESDAY INTO
WEDNESDAY AND THEN WEAKENS THIS LOW W/YET ANOTHER LOW FURTHER TO
THE E TAKING OVER BY THURSDAY AND ENDING THE PRECIP SOONER. THIS
WOULD MEAN SIGNIFICANT A SNOWFALL FOR THE CWA TUESDAY INTO WEDNESDAY
W/DRIER CONDITIONS ON THURSDAY. THE OPERATIONAL GFS HAS THIS LOW
DEVELOPING OFF THE MID ATLC COAST AND LIFTING NORTHWARD AND
INTENSIFYING W/POSSIBLE BLIZZARD CONDITIONS WEDNESDAY INTO
THURSDAY. TO ADD TO THE CONFUSION, 7 OUT OF THE 12 GFS ENSEMBLE
MEMBERS KEEP THIS LOW FURTHER S AND E BY THE SAME TIMEFRAME.
DECIDED TO GO W/LIKELY POPS(60-70%) FOR THE INTERIOR DOWNEAST AND
THE COAST FOR MONDAY INTO TUESDAY AND CHC POPS FURTHER NORTH.
TEMPERATURES LOOK COLD ENOUGH FOR SNOW ALL THE WAY TO THE COAST.
CONFIDENCE DROPS OFF WEDNESDAY INTO THURSDAY GIVEN THE
DISCREPANCIES IN THE LONG RANGE GUIDANCE. CONCERN IS THERE THAT
THE BLOCKING PATTERN SETTING UP OVER NORTHERN CANADA COULD LEAD TO
LOW PRES SYSTEMS BEING SHUNTED FURTHER S AND E. THEREFORE, KEPT
CHC POPS FOR THIS TIMEFRAME. THE DAYCREW CAN ASSESS THIS FURTHER
W/LATER MODEL RUNS. ADJUSTED THE GMOS MAXES DOWN WEDNESDAY INTO
THURSDAY BLENDING IN THE ECMWF TEMPERATURES. ALSO CUT BACK ON
WINDS SPEEDS FROM 40-50 MPH GUSTS DOWN TO 35 MPH. WOULD LIKE TO
SEE A BETTER CONSENSUS OF THE GUIDANCE BEFORE SHOOTING THAT HIGH.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: BRIEF PERIOD OF MVFR/IFR CONDITIONS POSSIBLE DUE TO
SNOW SHOWERS AND CEILINGS THIS AFTERNOON INTO THIS EVENING...
OTHERWISE VFR CONDITIONS.
SHORT TERM: COULD BE SEEING SOME MVFR CONDITIONS FOR THE NORTHERN
TERMINALS SATURDAY AND THEN CONDITIONS LOOK LIKE THEY WILL GO VFR
THROUGH SUNDAY. THE CHALLENGE COMES MONDAY INTO TUESDAY W/A POSSIBLE
STORM SYSTEM BRINGING SNOW AND POSSIBLE ICING W/MVFR TO IFR.
&&
.MARINE...
NEAR TERM: HAVE USED A BLEND OF THE NAM12 AND GFS40 TO INITIALIZE
THE WINDS. HAVE INCREASED THE WIND SPEED SEVERAL KNOTS LATER
TONIGHT AS COLDER AIR MOVES ACROSS THE WATERS. FOR WAVES: EXPECT
SOUTHWEST FETCH TO DEVELOP ACROSS THE GULF OF MAINE THIS AFTERNOON
IN TIGHT GRADIENT AHEAD OF APPROACHING FRONT. PRIMARY WAVE GROUP
BUILDING TO 5-6 FEET/6 SECONDS. SECONDARY LONG PERIOD WAVE GROUP
FROM SOUTHEAST. WILL MOVE STARTING TIME FOR SCA TO 2100Z.
SHORT TERM: SCA CONDITIONS MAY NEED TO BE EXTENDED THROUGH
SATURDAY AFTERNOON AS NW WINDS COULD GUST TO 25 KTS W/CAA OVER THE
WATERS ESPECIALLY THE OUTER ZONES. USE A NAM12/GFS BLEND FOR THE
SUSTAINED WINDS SHOWING 15-20 KTS W/GUSTS HITTING 25 KTS ON
SATURDAY. WINDS DROP OFF SATURDAY NIGHT RIGHT THROUGH SUNDAY TO
10-15 KTS. SEAS WILL REMAIN 3-5 FT AT BEST FOR THIS TIME PERIOD.
WINDS/SEAS COULD INCREASE SIGNIFICANTLY MONDAY NIGHT INTO TUESDAY
AS A LOW PRES SYSTEM APCHS FORM THE S. ENE WINDS COULD HIT SCA OR
EVEN GALES. DECIDED TO BACK AWAY FROM THE GMOS ATTM AND CUT BACK
THOSE SPEEDS BY 10 KTS. THIS MEANS SUSTAINED WINDS OF 20-25 KTS
AND GUSTS UP TO 35 KTS. INCREASED THE SEAS UP TO 8-10 FT BY TUESDAY.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST
SATURDAY FOR ANZ050>052.
&&
$$
NEAR TERM...CB/MIGNONE
SHORT TERM...HEWITT
LONG TERM...HEWITT
AVIATION...CB/MIGNONE
MARINE...MIGNONE/HEWITT
AREA FORECAST DISCUSSION
NWS CARIBOU ME
626 AM EST FRI DEC 14 2012
.SYNOPSIS...
WEAK LOW PRESSURE WILL PASS NORTH OF THE AREA THIS MORNING WITH A
COLD FRONTAL PASSAGE LATER TODAY AND TONIGHT. HIGH PRESSURE BUILDS
NORTH OF THE REGION SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE 0625 EST: HAVE ADJUSTED TEMPERATURE...WEATHER AND POPS.
LOW PRESSURE IS CURRENTLY PASSING TO THE NORTH OF THE STATE. A
STRONG COLD FRONT TRAILING THE LOW WILL APPROACH FROM THE WEST
THIS MORNING THE MOVE ACROSS THE STATE DURING THE AFTERNOON.
STRONG COLD ADVECTION BEHIND THE FRONT ALONG WITH AN UPPER TROUGH
WILL RESULT IN UNSTABLE CONDITIONS RESULTING IN SNOW SQUALLS
ESPECIALLY IN THE NORTH DURING THE AFTERNOON INTO THE EVENING.
WILL USE THE RUC13 TO INITIALIZE THE POP GRIDS THROUGH THE MORNING
THEN TRANSITION TO A BLEND OF THE NAM12 ...GFS40 ...SREF AND
ECMWF. FOR QPF WILL ALSO USE SAME MODEL BLEND AND EXCHANGE THE
NAM12 FOR NAM80. FOR SNOW AMOUNTS WILL RUN SNOW FROM THICKNESS
TOOL ON NAM/QPF GRIDS. THE GMOS WAS USED TO INITIALIZE THE
TEMPERATURE AND DEW POINT GRIDS. HAVE MANUALLY ADJUSTED MAXIMUM
AND MINIMUM TEMPERATURES. USED A NAM12/GMOS BLEND FOR WIND SPEED.
FOR WIND GUSTS WILL USE 200 PERCENT OF SUSTAINED SPEED WITH GOOD
MIXING EXPECTED.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
COLDER WEATHER IN STORE FOR THE WEEKEND.
ARCTIC AIR WILL CONTINUE TO PUSH INTO THE CWA ON SATURDAY W/NNW
WINDS ADDING A CHILL TO THE AIR. THIS WILL MEAN SATURDAY`S HIGHS
WILL BE BELOW NORMAL FOR THE IDES OF DECEMBER. A COLD NNW FLOW OFF
THE OPEN ST. LAWRENCE WILL LEAD TO CLOUDS ACROSS NORTHERN 1/2 OF
THE CWA W/SOME FLURRIES OR BANDS OF LIGHT SNOW THROUGH SATURDAY
AFTERNOON. THE NAM AND GFS TEND TO STRUGGLE W/THSI TYPE OF SETUP.
THE CANADIAN GEM LOOKS LIKE IT PICKS UP ON THIS WELL AND DECIDED
TO USE IT TO SET UP THE FORECAST FOR SATURDAY INTO SATURDAY NIGHT.
SKIES WILL GRADUALLY CLEAR ACROSS THE NORTHERN AREAS SATURDAY
NIGHT AS THE FLOW WEAKENS WHILE THE CENTRAL AND DOWNEAST REGION
REMAIN CLEAR. ALL THIS ALLOWING FOR SOME COLD TEMPERATURES BY
EARLY SUNDAY MORNING. STAYED CLOSE TO THE DAYCREW`S ASSESSMENT OF
READINGS AOB 0F ACROSS THE NORTH AND WEST AND IN THE SINGLE
NUMBERS FOR THE CENTRAL AND DOWNEAST REGIONS.
HIGH PRES WILL MOVE ACROSS NORTHERN QUEBEC AND RIDGE DOWN ACROSS
THE REGION ON SUNDAY. AT THE SAME TIME, LOW PRES MOVING ACROSS THE
GREAT LAKES REGION IS FCST TO RE-DEVELOP OFF THE NJ COAST BY
SUNDAY NIGHT. ATTM, DECIDED TO KEEP THE CWA DRY BANKING ON THE
STRONG HIGH TO THE NORTH HOLDING ON LONGER. THIS MATCHES UP WELL
THE LATEST RUNS OF THE NAM/GFS AND ECMWF. WE WILL SEE INCREASING
CLOUDS FROM THE SW DURING THE DAY W/A GRADUAL MODERATION IN
TEMPERATURES BUT STILL BELOW NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THINGS BEGIN TO GET COMPLICATED ESPECIALLY WEDNESDAY INTO
THURSDAY. DETAILS ARE BELOW.
THE 00Z RUNS OF THE ECMWF/OPERATIONAL GFS AND ITS MEAN ENSEMBLE
SUPPORT LOW PRES REDEVELOPING NEAR NJ SUNDAY NIGHT AND THEN SLOWLY
MOVING ENE OFF THE LONG ISLAND COAST. THE GFS IS MOST PROMINENT
W/THIS FEATURE WHILE THE ECWMF AND THE CANADIAN GLOBAL KEEP THE
SYSTEM LESS AMPLIFIED AND SHOW THE HIGH PRES RIDGE HOLDING ON
LONGER KEEPING THE BULK OF THE PRECIP FURTHER S. DECIDED TO BLEND
THE ECMWF AND GFS FOR THIS SYSTEM SUNDAY NIGHT INTO MONDAY. THIS MEANS
CHC POPS SUNDAY NIGHT FOR THE INTERIOR DOWNEAST AND COAST WHICH
MATCHES UP WELL W/GYX AND STAYED DRY FURTHER NORTH GIVEN THE
RIDGE HOLDING IN LONGER.
THE CHALLENGE NOW COMES FOR MONDAY RIGHT INTO LATE WEEK. THE
ECMWF DOES SHOW A MORE SIGNIFICANT LOW MOVING ACROSS THE DELMARVA
ON MONDAY AND LIFTING THROUGH THE GULF OF MAINE LATER TUESDAY INTO
WEDNESDAY AND THEN WEAKENS THIS LOW W/YET ANOTHER LOW FURTHER TO
THE E TAKING OVER BY THURSDAY AND ENDING THE PRECIP SOONER. THIS
WOULD MEAN SIGNIFICANT A SNOWFALL FOR THE CWA TUESDAY INTO WEDNESDAY
W/DRIER CONDITIONS ON THURSDAY. THE OPERATIONAL GFS HAS THIS LOW
DEVELOPING OFF THE MID ATLC COAST AND LIFTING NORTHWARD AND
INTENSIFYING W/POSSIBLE BLIZZARD CONDITIONS WEDNESDAY INTO
THURSDAY. TO ADD TO THE CONFUSION, 7 OUT OF THE 12 GFS ENSEMBLE
MEMBERS KEEP THIS LOW FURTHER S AND E BY THE SAME TIMEFRAME.
DECIDED TO GO W/LIKELY POPS(60-70%) FOR THE INTERIOR DOWNEAST AND
THE COAST FOR MONDAY INTO TUESDAY AND CHC POPS FURTHER NORTH.
TEMPERATURES LOOK COLD ENOUGH FOR SNOW ALL THE WAY TO THE COAST.
CONFIDENCE DROPS OFF WEDNESDAY INTO THURSDAY GIVEN THE
DISCREPANCIES IN THE LONG RANGE GUIDANCE. CONCERN IS THERE THAT
THE BLOCKING PATTERN SETTING UP OVER NORTHERN CANADA COULD LEAD TO
LOW PRES SYSTEMS BEING SHUNTED FURTHER S AND E. THEREFORE, KEPT
CHC POPS FOR THIS TIMEFRAME. THE DAYCREW CAN ASSESS THIS FURTHER
W/LATER MODEL RUNS. ADJUSTED THE GMOS MAXES DOWN WEDNESDAY INTO
THURSDAY BLENDING IN THE ECMWF TEMPERATURES. ALSO CUT BACK ON
WINDS SPEEDS FROM 40-50 MPH GUSTS DOWN TO 35 MPH. WOULD LIKE TO
SEE A BETTER CONSENSUS OF THE GUIDANCE BEFORE SHOOTING THAT HIGH.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: BRIEF PERIOD OF MVFR/IFR CONDITIONS POSSIBLE DUE TO
SNOW SHOWERS AND CEILINGS ...OTHERWISE VFR CONDITIONS.
SHORT TERM: COULD BE SEEING SOME MVFR CONDITIONS FOR THE NORTHERN
TERMINALS SATURDAY AND THEN CONDITIONS LOOK LIKE THEY WILL GO VFR
THROUGH SUNDAY. THE CHALLENGE COMES MONDAY INTO TUESDAY W/A POSSIBLE
STORM SYSTEM BRINGING SNOW AND POSSIBLE ICING W/MVFR TO IFR.
&&
.MARINE...
NEAR TERM: HAVE USED A BLEND OF THE NAM12 AND GFS40 TO INITIALIZE
THE WINDS. HAVE INCREASED THE WIND SPEED SEVERAL KNOTS LATER
TONIGHT AS COLDER AIR MOVES ACROSS THE WATERS. FOR WAVES: EXPECT
SOUTHWEST FETCH TO DEVELOP ACROSS THE GULF OF MAINE THIS AFTERNOON
IN TIGHT GRADIENT AHEAD OF APPROACHING FRONT. PRIMARY WAVE GROUP
BUILDING TO 5-6 FEET/6 SECONDS. SECONDARY LONG PERIOD WAVE GROUP
FROM SOUTHEAST. WILL MOVE STARTING TIME FOR SCA TO 2100Z.
SHORT TERM: SCA CONDITIONS MAY NEED TO BE EXTENDED THROUGH
SATURDAY AFTERNOON AS NW WINDS COULD GUST TO 25 KTS W/CAA OVER THE
WATERS ESPECIALLY THE OUTER ZONES. USE A NAM12/GFS BLEND FOR THE
SUSTAINED WINDS SHOWING 15-20 KTS W/GUSTS HITTING 25 KTS ON
SATURDAY. WINDS DROP OFF SATURDAY NIGHT RIGHT THROUGH SUNDAY TO
10-15 KTS. SEAS WILL REMAIN 3-5 FT AT BEST FOR THIS TIME PERIOD.
WINDS/SEAS COULD INCREASE SIGNIFICANTLY MONDAY NIGHT INTO TUESDAY
AS A LOW PRES SYSTEM APCHS FORM THE S. ENE WINDS COULD HIT SCA OR
EVEN GALES. DECIDED TO BACK AWAY FROM THE GMOS ATTM AND CUT BACK
THOSE SPEEDS BY 10 KTS. THIS MEANS SUSTAINED WINDS OF 20-25 KTS
AND GUSTS UP TO 35 KTS. INCREASED THE SEAS UP TO 8-10 FT BY TUESDAY.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST
SATURDAY FOR ANZ050>052.
&&
$$
NEAR TERM...MIGNONE
SHORT TERM...HEWITT
LONG TERM...HEWITT
AVIATION...MIGNONE
MARINE...MIGNONE/HEWITT
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
554 AM CST FRI DEC 14 2012
.AVIATION...
STRATUS...STRONG TSRA...HIGH WINDS...AND BLOWING DUST WILL MAKE
FOR DETERIORATING CONDITIONS TODAY. HIGH CONFIDENCE THAT MORNING
MVFR STRATUS WILL REMAIN LARGELY UNDISTURBED THROUGH EARLY
AFTERNOON. THIS LAYER MAY OCCASIONALLY DROP TO HIGH-END IFR
LEVELS BEFORE 16Z AT LBB...BUT A MUCH BETTER CHANCE OF IFR
CONDITIONS AT LBB WILL ACCOMPANY A FAST-MOVING COLD FRONT AROUND
22Z AS 30-40 KNOT SWLY WINDS REDUCE VISBYS TO 1SM OR LESS IN BLDU.
CDS SHOULD ESCAPE THESE EFFECTS...HOWEVER BOTH TERMINALS WILL
LIKELY SEE A BROKEN LINE OF TSRA ACCOMPANY THE FRONT COMPLETE WITH
LOCALLY DMGG WINDS. SUSPENDED DUST MAY LINGER FOR A FEW HOURS AT LBB
AFTER SUNSET WHEN WINDS SUBSIDE...BUT AS A WHOLE VFR CONDITIONS
SHOULD EMERGE BY EARLY EVENING AT BOTH STATIONS.
&&
.PREV DISCUSSION... /ISSUED 501 AM CST FRI DEC 14 2012/
SHORT TERM...
MULTI-FACETED AND EXCEPTIONALLY ACTIVE WEATHER FOR MID-DECEMBER
AWAITS THE SOUTH PLAINS LATER TODAY AS A VIGOROUS UPPER LOW LIFTS
NORTHEAST FROM NORTHERN BAJA IN THE FORM OF A NEGATIVELY TILTED
TROUGH. EARLY MORNING WATER VAPOR DEPICTION OF SAID LOW WAS QUITE
IMPRESSIVE AND FEATURED A DEEPENING PLUME OF SUBTROPICAL MOISTURE
AND SOME THUNDERSTORMS WELL IN ITS ADVANCE. ABUNDANT LOW-LEVEL
MOISTURE ADVECTION CONTINUED OVER WEST TX THIS MORNING AND WILL
ONLY CONTINUE THROUGH 18Z AS RESPECTABLE PRESSURE FALLS AROUND
7MB/6HR FOCUS IN ERN NM AHEAD OF THE EJECTING WAVE. THIS WILL KEEP
MOIST SOUTHERLY WINDS...STRATUS AND SOME FOG INTACT LONGER THAN
ORIGINALLY FORECAST BEFORE STRONG HEIGHT FALLS /60+ METERS AT
500MB/ UNFOLD BY EARLY AFTN ALONG THE NM-TX STATE LINE. ALONG WITH
A 135 KNOT UPPER SPEED MAX...A PACIFIC FRONT ACCOMPANYING THE
LEADING EDGE OF HEIGHT FALLS SHOULD EASILY SECURE DEEP ASCENT
WHILE PUTTING OUR SEASONABLY HIGH DEWPOINTS TO WORK.
CONSIDERING THE FLOW AHEAD OF THIS TROUGH IS MORE MERIDIONAL THAN
MODELS INDICATED JUST A FEW DAYS AGO...THE CHANCES OF A DRY FROPA
HAVE NOW GREATLY DIMINISHED. AFTERNOON POPS WERE DOUBLED NEARLY
AREA WIDE WITH JUST SLIGHT CHANCES OF MRNG SHOWERS CONFINED MAINLY
OFF THE CAPROCK WHERE DEEPER MOIST ADVECTION WITHIN A LLJ AXIS
COULD FAVOR VERY LIGHT PRECIP.
ALTHOUGH STRATUS WILL BE VERY SLOW TO ERODE...AMPLE MID-LEVEL
COOLING ACCOMPANYING THE UPPER TROUGH IS STILL SHOWN TO GARNER
WEAK SBCAPE AOB 600 J/KG BY 21Z WITH SURFACE TEMPS IN THE 50S-
60S. IT IS NOT UNCOMMON TO SEE SOME SEVERE CONVECTIVE MODES UNFOLD
IN SUCH LOW CAPE AND HIGH SHEAR ENVIRONMENTS PROVIDED
STRONG/FOCUSED ASCENT EMERGES. INITIAL SWODY1 ACCOUNTS FOR THIS
SCENARIO AND SEVERAL HI RES MODELS INCLUDING THE TTU-WRF DEPICT A
BROKEN LINE OF PARTICULARLY STRONG CELLS ACCOMPANYING FROPA. SUCH
A SCENARIO INVOLVING DMGG DOWNBURST WINDS OCCURRED HERE IN MID
DECEMBER 1993 FROM A SIMILAR SYNOPTIC PATTERN. AS WAS THE CASE
THEN...SEVERE WIND GUSTS WOULD BE THE DOMINANT THREAT WITH STORMS
TODAY AS STRONG KINEMATIC FLOW OVERSPREADS THE REGION. VERY MEAGER
CAPE IN THE HAIL GROWTH REGION SHOULD KEEP SEVERE HAIL PRODUCTION
AT BAY.
IN ADDITION TO A THREAT OF SEVERE CONVECTIVE WINDS...PATTERN
RECOGNITION BEHIND THE FRONT BY MID/LATE AFTERNOON DOES FAVOR AN
ABBREVIATED NON-CONVECTIVE HIGH WIND EVENT. A 500MB WIND MAX OF 100
KNOTS IS PROGGED TO OVERSPREAD OUR SWRN COUNTIES BY 21Z COMPLETE
WITH 60-70 KNOTS AT THE TOP OF THE MIXING LAYER AROUND 700MB OVER
MUCH OF THE CAPROCK. STRONG POST-FRONTAL SUBSIDENCE AND DRYING ON
SWLY WINDS SHOULD ALLOW FOR AN ABBREVIATED WINDOW OF 40G58 MPH
CONDITIONS OR HIGHER IMMEDIATELY FOLLOWING THE PACIFIC FRONT UNTIL
BOUNDARY LAYER DECOUPLING ENSUES BY 00Z. MOS GUIDANCE IS WELL
SHORT OF HIGH WIND CRITERIA...BUT WE BELIEVE MUCH OF THIS IS DUE
TO THE RELATIVELY SHORT DURATION OF HIGH WINDS THAT WE ANTICIPATE
WILL DEVELOP LATE IN THE DAY. TTU-WRF AND HRRR CONTINUE TO
CHAMPION SUCH CONDITIONS FOR A FEW HOURS FOLLOWING FROPA WITH
GUSTS AROUND 60 MPH TAKING AIM MAINLY WEST OF I-27.
LONG TERM...
ALTHOUGH WIND SPEEDS WILL DECREASE A BIT TONIGHT INTO SATURDAY
MORNING...EXPECT THEM TO ONCE AGAIN RAMP UP SOME SATURDAY
AFTERNOON AS ANOTHER APPROACHING SHORTWAVE TROF KEEPS A TIGHT
PRESSURE GRADIENT OVER THE REGION. SOIL WILL HAVE DRIED OUT SOME
FROM ANY RAINFALL TODAY AND CONDITIONS WILL ONCE AGAIN FAVOR SOME
AREAS OF BLOWING DUST SATURDAY AFTERNOON. THIS STORM SYSTEM WILL
RAPIDLY PUSH EAST SATURDAY NIGHT BEFORE ANOTHER TROF PUSHES OVER
THE AREA FOR SUNDAY AFTERNOON. THIS THIRD STORM SYSTEM WILL NOT BE
QUITE AS STRONG BUT WILL LIKELY RESULT IN BREEZY CONDITIONS AGAIN
FOR SUNDAY AFTERNOON. THROUGH THE WEEKEND...TEMPERATURES WILL ALSO
SLOWLY COOL AS CONTINUED COLD AIR ADVECTION TAKES PLACE KEEPING
READINGS CLOSE TO NORMAL FOR THIS TIME OF YEAR.
DRY WEATHER WILL BE EXPECTED FOR THE FIRST PART OF NEXT WEEK AS
DRY NORTHWESTERLY FLOW GRADUALLY TRANSITIONS TO SOUTHWESTERLY BY
MID-WEEK. THIS WILL ALLOW TEMPERATURES TO ONCE AGAIN CLIMB TO
ABOVE NORMAL THROUGH WEDNESDAY. ALSO BY MID-WEEK...ANOTHER
CANADIAN COLD FRONT WILL PUSH SOUTH THROUGH THE CENTRAL PLAINS
AND ARRIVE SOMETIME LATE WEDNESDAY INTO THURSDAY MORNING. THIS
FRONTAL PASSAGE SHOULD BE DRY AS LITTLE MOISTURE RECOVERY TAKES
PLACE BEFORE IT MOVES THROUGH. THIS FRONT WILL DROP TEMPERATURES
BACK DOWN TO NORMAL FOR THE END OF THE WEEK.
JORDAN
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 58 30 57 26 55 / 60 0 0 0 0
TULIA 60 33 59 28 55 / 60 0 0 0 0
PLAINVIEW 60 33 59 28 55 / 60 0 0 0 0
LEVELLAND 62 32 60 30 57 / 60 0 0 0 0
LUBBOCK 62 34 61 31 57 / 60 0 0 0 0
DENVER CITY 62 31 62 32 59 / 40 0 0 0 0
BROWNFIELD 63 33 62 31 59 / 50 0 0 0 0
CHILDRESS 62 40 65 34 61 / 60 20 0 0 0
SPUR 62 38 65 34 64 / 50 10 0 0 0
ASPERMONT 64 41 68 38 66 / 30 20 0 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING FROM 2 PM THIS AFTERNOON TO 6 PM CST THIS
EVENING FOR THE FOLLOWING ZONES:
TXZ021>023-027>029-033>035-039>041.
&&
$$
93
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
501 AM CST FRI DEC 14 2012
.SHORT TERM...
MULTI-FACETED AND EXCEPTIONALLY ACTIVE WEATHER FOR MID-DECEMBER
AWAITS THE SOUTH PLAINS LATER TODAY AS A VIGOROUS UPPER LOW LIFTS
NORTHEAST FROM NORTHERN BAJA IN THE FORM OF A NEGATIVELY TILTED
TROUGH. EARLY MORNING WATER VAPOR DEPICTION OF SAID LOW WAS QUITE
IMPRESSIVE AND FEATURED A DEEPENING PLUME OF SUBTROPICAL MOISTURE
AND SOME THUNDERSTORMS WELL IN ITS ADVANCE. ABUNDANT LOW-LEVEL
MOISTURE ADVECTION CONTINUED OVER WEST TX THIS MORNING AND WILL
ONLY CONTINUE THROUGH 18Z AS RESPECTABLE PRESSURE FALLS AROUND
7MB/6HR FOCUS IN ERN NM AHEAD OF THE EJECTING WAVE. THIS WILL KEEP
MOIST SOUTHERLY WINDS...STRATUS AND SOME FOG INTACT LONGER THAN
ORIGINALLY FORECAST BEFORE STRONG HEIGHT FALLS /60+ METERS AT
500MB/ UNFOLD BY EARLY AFTN ALONG THE NM-TX STATE LINE. ALONG WITH
A 135 KNOT UPPER SPEED MAX...A PACIFIC FRONT ACCOMPANYING THE
LEADING EDGE OF HEIGHT FALLS SHOULD EASILY SECURE DEEP ASCENT
WHILE PUTTING OUR SEASONABLY HIGH DEWPOINTS TO WORK.
CONSIDERING THE FLOW AHEAD OF THIS TROUGH IS MORE MERIDIONAL THAN
MODELS INDICATED JUST A FEW DAYS AGO...THE CHANCES OF A DRY FROPA
HAVE NOW GREATLY DIMINISHED. AFTERNOON POPS WERE DOUBLED NEARLY
AREA WIDE WITH JUST SLIGHT CHANCES OF MRNG SHOWERS CONFINED MAINLY
OFF THE CAPROCK WHERE DEEPER MOIST ADVECTION WITHIN A LLJ AXIS
COULD FAVOR VERY LIGHT PRECIP.
ALTHOUGH STRATUS WILL BE VERY SLOW TO ERODE...AMPLE MID-LEVEL
COOLING ACCOMPANYING THE UPPER TROUGH IS STILL SHOWN TO GARNER
WEAK SBCAPE AOB 600 J/KG BY 21Z WITH SURFACE TEMPS IN THE 50S-
60S. IT IS NOT UNCOMMON TO SEE SOME SEVERE CONVECTIVE MODES UNFOLD
IN SUCH LOW CAPE AND HIGH SHEAR ENVIRONMENTS PROVIDED
STRONG/FOCUSED ASCENT EMERGES. INITIAL SWODY1 ACCOUNTS FOR THIS
SCENARIO AND SEVERAL HI RES MODELS INCLUDING THE TTU-WRF DEPICT A
BROKEN LINE OF PARTICULARLY STRONG CELLS ACCOMPANYING FROPA. SUCH
A SCENARIO INVOLVING DMGG DOWNBURST WINDS OCCURRED HERE IN MID
DECEMBER 1993 FROM A SIMILAR SYNOPTIC PATTERN. AS WAS THE CASE
THEN...SEVERE WIND GUSTS WOULD BE THE DOMINANT THREAT WITH STORMS
TODAY AS STRONG KINEMATIC FLOW OVERSPREADS THE REGION. VERY MEAGER
CAPE IN THE HAIL GROWTH REGION SHOULD KEEP SEVERE HAIL PRODUCTION
AT BAY.
IN ADDITION TO A THREAT OF SEVERE CONVECTIVE WINDS...PATTERN
RECOGNITION BEHIND THE FRONT BY MID/LATE AFTERNOON DOES FAVOR AN
ABBREVIATED NON-CONVECTIVE HIGH WIND EVENT. A 500MB WIND MAX OF 100
KNOTS IS PROGGED TO OVERSPREAD OUR SWRN COUNTIES BY 21Z COMPLETE
WITH 60-70 KNOTS AT THE TOP OF THE MIXING LAYER AROUND 700MB OVER
MUCH OF THE CAPROCK. STRONG POST-FRONTAL SUBSIDENCE AND DRYING ON
SWLY WINDS SHOULD ALLOW FOR AN ABBREVIATED WINDOW OF 40G58 MPH
CONDITIONS OR HIGHER IMMEDIATELY FOLLOWING THE PACIFIC FRONT UNTIL
BOUNDARY LAYER DECOUPLING ENSUES BY 00Z. MOS GUIDANCE IS WELL
SHORT OF HIGH WIND CRITERIA...BUT WE BELIEVE MUCH OF THIS IS DUE
TO THE RELATIVELY SHORT DURATION OF HIGH WINDS THAT WE ANTICIPATE
WILL DEVELOP LATE IN THE DAY. TTU-WRF AND HRRR CONTINUE TO
CHAMPION SUCH CONDITIONS FOR A FEW HOURS FOLLOWING FROPA WITH
GUSTS AROUND 60 MPH TAKING AIM MAINLY WEST OF I-27.
&&
.LONG TERM...
ALTHOUGH WIND SPEEDS WILL DECREASE A BIT TONIGHT INTO SATURDAY
MORNING...EXPECT THEM TO ONCE AGAIN RAMP UP SOME SATURDAY
AFTERNOON AS ANOTHER APPROACHING SHORTWAVE TROF KEEPS A TIGHT
PRESSURE GRADIENT OVER THE REGION. SOIL WILL HAVE DRIED OUT SOME
FROM ANY RAINFALL TODAY AND CONDITIONS WILL ONCE AGAIN FAVOR SOME
AREAS OF BLOWING DUST SATURDAY AFTERNOON. THIS STORM SYSTEM WILL
RAPIDLY PUSH EAST SATURDAY NIGHT BEFORE ANOTHER TROF PUSHES OVER
THE AREA FOR SUNDAY AFTERNOON. THIS THIRD STORM SYSTEM WILL NOT BE
QUITE AS STRONG BUT WILL LIKELY RESULT IN BREEZY CONDITIONS AGAIN
FOR SUNDAY AFTERNOON. THROUGH THE WEEKEND...TEMPERATURES WILL ALSO
SLOWLY COOL AS CONTINUED COLD AIR ADVECTION TAKES PLACE KEEPING
READINGS CLOSE TO NORMAL FOR THIS TIME OF YEAR.
DRY WEATHER WILL BE EXPECTED FOR THE FIRST PART OF NEXT WEEK AS
DRY NORTHWESTERLY FLOW GRADUALLY TRANSITIONS TO SOUTHWESTERLY BY
MID-WEEK. THIS WILL ALLOW TEMPERATURES TO ONCE AGAIN CLIMB TO
ABOVE NORMAL THROUGH WEDNESDAY. ALSO BY MID-WEEK...ANOTHER
CANADIAN COLD FRONT WILL PUSH SOUTH THROUGH THE CENTRAL PLAINS
AND ARRIVE SOMETIME LATE WEDNESDAY INTO THURSDAY MORNING. THIS
FRONTAL PASSAGE SHOULD BE DRY AS LITTLE MOISTURE RECOVERY TAKES
PLACE BEFORE IT MOVES THROUGH. THIS FRONT WILL DROP TEMPERATURES
BACK DOWN TO NORMAL FOR THE END OF THE WEEK.
JORDAN
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 58 30 57 26 55 / 60 0 0 0 0
TULIA 60 33 59 28 55 / 60 0 0 0 0
PLAINVIEW 60 33 59 28 55 / 60 0 0 0 0
LEVELLAND 62 32 60 30 57 / 60 0 0 0 0
LUBBOCK 62 34 61 31 57 / 60 0 0 0 0
DENVER CITY 62 31 62 32 59 / 40 0 0 0 0
BROWNFIELD 63 33 62 31 59 / 50 0 0 0 0
CHILDRESS 62 40 65 34 61 / 60 20 0 0 0
SPUR 62 38 65 34 64 / 50 10 0 0 0
ASPERMONT 64 41 68 38 66 / 30 20 0 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING FROM 2 PM THIS AFTERNOON TO 6 PM CST THIS
EVENING FOR THE FOLLOWING ZONES:
TXZ021>023-027>029-033>035-039>041.
&&
$$
93/14
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
346 PM MST FRI DEC 14 2012
.SHORT TERM...UPPER TROUGH CURRENTLY MOVING ACROSS STATE WITH
SOUTHERLY FLOW ALOFT BECOMING MORE SOUTHWEST. QUITE A BIT OF
MOISTURE OVER AREA THOUGH WEB CAMS ACROSS MOUNTAINS INDICATING
MOST OF THE MOISTURE OVER THE RIDGES. DESPITE THE INCREASING MID
LEVEL ASCENT ASSOCIATED WITH THE TROUGH ALONG WITH LAPSE RATES
AROUND 6 C/KM...MOUNTAIN SNOW FALL HAS BEEN LIMITED AND CONFINED
TO THE HIGHER RIDGES. ACROSS PLAINS...PRECIPITATION HAS BEEN
CONFINED FAR NORTHEAST ZONES IN AREA OF LOWER SURFACE PRESSURE.
MODELS MOVE TROUGH INTO KANSAS WITH DURING THE EVENING WITH FLOW
ALOFT BECOMING WESTERLY. MID LEVEL ASCENT SHIFTS EAST WITH THE
TROUGH...WITH SUBSIDENCE SPREADING ACROSS STATE. MODEL CROSS
SECTIONS KEEP FAIRLY DEEP MOISTURE ACROSS MOUNTAINS. WITH
OROGRAPHICS BECOMING MORE FAVORABLE FOR SNOW FALL...SHOULD SEE A
BETTER CHANCE FOR SNOW. WILL KEEP ACCUMULATIONS LIGHT WITH THE
INCREASING SUBSIDENCE. ACROSS PLAINS....LATEST RUC KEEPS SOME
LIGHT QPF AND SNOW ACCUMUATION ACROSS THE FAR NORTHEAST SECTIONS
DURING THE EVENING...WITH DRY CONDITIONS AFTER MIDNIGHT. THIS
STILL SEEMS ON TRACK BASED ON TROUGH. WET BULB ZERO HEIGHTS
SUGGEST PRECIP TO BE MAINLY SNOW. ON SATURDAY...FLOW ALOFT BECOMES
WEST NORTHWEST WITH CONTINUED MOISTURE ACROSS MOUNTAINS. MODELS
SHOW NEXT SHORTWAVE MOVING INTO COLORADO DURING THE MORNING WITH
INCREASING MID LEVEL ASCENT. THIS WILL KEEP AT LEAST A CHANCE OF
MOUNTAIN SNOW ONGOING WHICH MAY BE ENHANCED DURING THE AFTERNOON
AS LAPSE RATES INCREASE TO AROUND 6 C/KM. AMOUNTS SHOULD REMAIN
BELOW ADVISORY CRITERIA. ACROSS PLAINS...CLOUDS TO INCREASE DURING
THE MORNING AS SURFACE WINDS BECOME NORTHWEST. WITH MID LEVEL
ASCENT MOVING INTO THE AREA...COULD SEE SOME SHOWERS MOVE OFF THE
FOOTHILLS ACROSS THE NORTHERN PLAINS DURING THE AFTERNOON. MODELS
SHOW THE SHOWERS CONFINED TO AREAS NORTH AND EAST OF DENVER.
LATEST GFS SHOWING WINDS BECOMING NORTHEAST AFTER 21Z WHICH COULD
HELP INCREASE PRECIP CHANCES. FOR NOW WILL MAINTAIN THE SLIGHT
CHANCE. FORECAST SOUNDINGS SUGGEST TEMPERATURES TO BE WARM ENOUGH
FOR RAIN RATHER THAN SNOW.
.LONG TERM...A PROGRESSIVE UPPER LEVEL FLOW PATTERN WILL DOMINATE
THE WEATHER THROUGH EARLY NEXT WEEK...BEFORE AN UPPER RIDGE
DEVELOPS THROUGH THE MIDDLE OF THE WEEK. THE WESTERLY FLOW ALOFT
WILL BRING WEAK SHOTS OF MOISTURE TO THE MOUNTAINS AS EMBEDDED
SHORT WAVE TROUGHS PASS OVER THE STATE. THE PLAINS WILL BE LEFT
WITH CONTINUED DRY...DOWNSLOPING FLOW. THE FIRST UPPER TROUGH TO
MOVE OVER THE STATE WILL BE SATURDAY NIGHT AND SUNDAY MORNING.
EARLY IN THE WEEK...SOME DRYING WILL OCCUR AS ZONAL FLOW CONTINUES
OVER THE STATE. THE NEXT...STRONGER TROUGH WILL BE MOVING OVER THE
STATE ON WEDNESDAY AND WEDNESDAY NIGHT. THIS SYSTEM MAY HAVE
ENOUGH AMPLITUDE TO PRODUCE SOME PRECIPITATION ON THE PLAINS...
BUT WILL NEED TO SEE HOW LATER MODEL RUNS HANDLE THE DEVELOPMENT
OF THE TROUGH. FOR NOW WILL ONLY MENTION SNOW IN THE MOUNTAIN
AREAS. AFTER THE MID-WEEK TROUGH...THE ECMWF AND GFS SHOW STRONGER
RIDGING OVER THE WESTERN U.S. WHICH WILL BRING WARMER TEMPERATURES
TO THE REGION.
&&
.AVIATION...PRECIPITATION CONFINED TO EASTERN PLAINS EAST OF
DENVER. AS SYSTEM MOVES EAST OF COLORADO...PRECIP TO HEAD EAST AS
WELL. VFR TO CONTINUE...NOT ANTICIPATING CEILINGS TO LOWER TO 6000
FEET AGL AT THIS TIME. LIGHT EASTERLY WINDS TO BECOME SOUTHERLY AS
DRAINAGE FLOW DEVELOPS...WITH A WESTERLY COMPONENT AT BJC. SPEEDS
TO REMAIN AROUND 8 KTS. ON SATURDAY...WINDS TO BECOME NORTHWEST BY
16Z. A FEW RAIN SHOWERS ARE POSSIBLE DURING THE AFTERNOON..WITH
POSSIBLE CEILINGS AROUND 6000 FEET AGL.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....DANKERS
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
940 AM MST FRI DEC 14 2012
.UPDATE...
&&
.SHORT TERM...UPPER TROUGH MOVING INTO COLORADO WITH MOIST SOUTHERLY
FLOW ALOFT ACROSS AREA. RADAR SHOWING SNOW BEGINNING TO SPREAD
INTO SOUTH PARK. WEB CAMS INDICATING SOME OBSCURRED RIDGES ALONG
THE CONTINENTAL DIVIDE OF SUMMIT COUNTY...WITH PERHAPS SOME LIGHT
SNOW THERE. UPPER TROUGH STILL PROGGED TO MOVE QUICKLY NORTHEAST
ACROSS THE AREA TROUGH THE AFTERNOON WITH INCREASING MID LEVEL QG
ASCENT AND LAPSE RATES. THUS A GOOD CHANCE OF SNOW STILL IN LINE
FOR THE MOUNTAINS...THOUGH FLOW NOT FAVORABLE FOR DECENT AMOUNTS.
ACROSS PLAINS...SURFACE LOW ALONG FOOTHILLS TO MOVE TOWARD THE
NEBRASKA-KANSAS BORDER DURING THE AFTERNOON. THIS TO PROVIDE SOME
LOCAL DOWNSLOPE FLOW ACROSS URBAN CORRIDOR WHICH COULD LIMIT
PRECIP CHANCES. OVERALL...THE LATEST MODELS SHOW BEST CHANCE FOR
PRECIP TOWARDS THE EASTERN COLORADO BORDER. FORECAST SOUNDING
STILL INDICATING A POSSIBILITY OF A RAIN AND SNOW MIX ACROSS THE
LOWER ELEVATIONS...STILL SEEM REASONABLE EVEN WITH HIGHS EXPECTED
TO BE IN THE LOWER AND MIDDLE 40S. CURRENT FORECASTS STILL SEEM
ON TRACK...ONLY MINOR ADJUSTMENTS AT THIS TIME.
.AVIATION...CURRENT FORECASTS SEEM ON TRACK. LATEST HRRR AND RAP
INDICATING PRECIPITATION MOVING ACROSS THE DENVER AREA AROUND 18Z
WHILE THE OTHER MODELS KEEP THE PRECIP EAST OF THE AREA AIRPORTS.
LATEST RADAR IS SHOWING SOME PRECIP MOVING INTO SOUTHERN DOUGLAS
COUNTY. FOR NOW WILL CONTINUE WITH A VCSH AND UPDATE AS NEEDED.
CEILINGS MAY NEED TO BE LOWERED IF SHOWERS SPREAD ACROSS THE AREA
AIRPORTS.
&&
.PREV DISCUSSION... /ISSUED 412 AM MST FRI DEC 14 2012/
SHORT TERM...AN UPPER LEVEL TROUGH OVER THE SWRN US WILL EJECT
QUICKLY ACROSS THE AREA THIS AFTN THRU THE EARLY EVENING HOURS. QG
FIELDS SHOW SOME MID LVL ASCENT AS SYSTEM MOVES ACROSS ALTHOUGH
WITH LAPSE RATES AROUND 6 C/KM. OVERALL FLOW IN THE MTNS WILL BE
SLY THRU THE AFTN AND THEN BECOME MORE WNW THIS EVENING AS THE
UPPER LEVEL TROUGH PASSES. THUS SHOULD SEE SOME SNOW ESPECIALLY
AS OROGRAPHIC COMPONENT BECOMES BETTER BY EARLY THIS EVENING WITH
SOME LIGHT ACCUMULATIONS. OVER NERN CO SFC LOW PRESSURE WILL
DEVELOP OVER THE AREA TODAY AND THEN MOVE INTO THE CNTRL PLAINS BY
TONIGHT. OVERALL SFC PTRN IS NOT REAL FAVORABLE FOR PCPN HOWEVER
WITH INCREASING MOISTURE AND MID LVL ASCENT WITH UPPER LEVEL
TROUGH WILL SEE A CHC OF PCPN MOSTLY OVER THE PLAINS. THE RAP
MODEL KEEPS A CHC OF PCPN CLOSER TO THE FOOTHILLS IN THE AFTN
WHILE ALL OF THE OTHER MODELS ARE CONSIDERABLY DRIER. FOR NOW WILL
JUST MENTION A SLIGHT CHC OF PCPN AROUND DENVER AND KEEP AREAS
FURTHER NORTH DRY. WET BULB ZEROS WOULD SUGGEST A MIXTURE OF RAIN
AND SNOW AT LOWER ELEVATIONS THIS AFTN WITH A MAINLY SNOW THIS
EVENING. AS FOR HIGHS WITH CONSIDERABLE CLOUD COVER AND SOME
COLLING OCCURRING IN THE LOWER LEVELS WILL KEEP HIGHS IN THE LOWER
TO MID 40S ACROSS NERN CO.
FOR TONIGHT THE UPPER LEVEL TROUGH WILL MOVE QUICKLY EAST OF THE
AREA WITH SOME LINGERING SNOW OVER THE FAR NERN PLAINS THROUGH
MIDNIGHT BEFORE ENDING. IN THE MTNS WILL CONTINUE TO SEE SOME
OROGRAPHIC SNOW OVERNIGHT.
LONG TERM...FIRST IN A SERIES OF SHORTWAVE TROUGHS WHISKED ALONG BY
A MODERATELY STRONG WESTERLY FLOW ALOFT SHOULD BE WELL EAST OF THE
STATE BY SATURDAY MORNING. WEST-NORTHWESTERLY LOW-LEVEL FLOW DURING
THE MORNING HOURS AIDS IN DRYING THE BOUNDARY LAYER EAST OF THE
MTNS. SHOULD SEE A FAIR AMOUNT OF SUNSHINE TO START THE DAY BEFORE
THE RETURN OF MOSTLY CLOUDY SKIES IN THE AFTERNOON AS THE NEXT IN
THE SERIES OF SHORTWAVE TROUGH WHICH MODELS SHOW TRAVERSING THE
STATE LATE SATURDAY AFTERNOON AND OVERNIGHT. THIS WAVE APPEARS TO DE-
AMPLIFY SOME AS IT PASSES OVER THE AREA SATURDAY EVENING. AS THIS IS
GOING ON...MODELS ALSO SHOW A WEAK COLD FRONT BACKING INTO NERN
COLORADO WHICH CAUSES W-NWLY SFC WINDS TO TURN N-NELY FOR SEVERAL
HOURS IN THE EVENING. MODELS...PARTICULARLY THE GFS...SHOW A BAND OF
LIGHT PCPN FORMING ALONG THIS FRONTAL BOUNDARY AS IT SLIPS S-
SWWRD...POSSIBLY AS FAR WEST AS EASTERN PORTIONS OF THE DENVER METRO
AREA BY ERLY IN THE EVENING. SHWRS UP ALONG THE WYOMING BORDER IN
THE AFTERNOON SHOULD START OUT AS RAIN WITH TEMPS IN THE 40S. THEN
AS TEMPS FALL AND SHOWERS BECOME A BIT MORE NUMEROUS FARTHER
SOUTH...PCPN IS EXPECTED TO CHANGE TO A RAIN/SNOW MIX IN THE
EVENING. COULD SEE A FEW POCKETS OF VERY LIGHT SNOW ACCUMULATION
WELL EAST OF THE I-25 CORRIDOR...BUT OVERALL NOT LOOKING FOR ANY
ACCUMULATION ON THE PLAINS. IN THE HIGH COUNTRY...SCATTERED TO
LIKELY POPS ARE IN ORDER THROUGHOUT THE DAY...WITH THE BEST CHANCE
FOR MEASURABLE SNOW ONCE AGAIN ALONG AND WEST OF THE CONTINENTAL
DIVIDE DUE TO THE WESTERLY FLOW AT MTN TOP LEVEL. THIS SYSTEM DOES
NOT LOOK LIKE A BIG SNOW PRODUCER FOR OUR PART OF THE
STATE...PROBABLY NO MORE THAN 3-4 INCHES AT BEST ON WINDWARD SLOPES
AND PERHAPS AN INCH OR SO ON THE VALLEY FLOORS BY LATE SATURDAY
EVENING.
ANOTHER UPPER AIR SYSTEM...THOUGH NOT AS STRONG AS ITS TWO
PREDECESSORS...DROPS IN FROM IDAHO/NRN UTAH DURING THE DAY SUNDAY
BRINGS YET ANOTHER SHOT OF SNOWFALL TO THE NORTH-CENTRAL MOUNTAINS
BY SUNDAY AFTERNOON AND EVENING...AND POSSIBLY A FEW RAIN/SNOW
SHOWERS TO THE NERN CORNER OF THE STATE BY EVENING. AGAIN...
NORTHWEST FACING MTN SLOPES COULD PICK UP ANOTHER FEW INCHES OF
SNOW...WITH PERHAPS AN INCH OF SNOW ON VALLEY FLOORS... AND NO
ACCUMULATION ON THE PLAINS. THIS WEATHER MAKER IS FORECAST TO
QUICKLY MOVE OUT BY MONDAY MORNING AS A STRONG HIGH PRESSURE RIDGE
BUILDS IN OVER THE GREAT BASIN. THIS RIDGE MOVES EAST ON MONDAY AND
TRAVERSES THE STATE ON TUESDAY PRODUCING PROBABLY THE WARMEST
TEMPERATURES OF THE WEEK ALONG WITH A DECENT AMOUNT OF
SUNSHINE...ESPLY EAST OF THE MTNS. BY WEDNESDAY...MEDIUM RANGE
MODELS SHOW YET ANOTHER TROUGH SWINGING ACROSS THE REGION FROM THE
CENTRAL GREAT BASIN...POTENTIALLY BRINGING MORE SNOW TO THE HIGH
COUNTRY AND POSSIBLY A FEW RAIN SHOWERS TO LOWER ELEVATIONS.
AVIATION...RAP SHOWS A CHC OF A RAIN/SNOW SHOWERS THIS AFTN WHILE THE
NAM AND GFS KEEP MOST OF THE ACTIVITY EAST OF THE AIRPORT. FOR
NOW WILL JUST MENTION VCTY IN THE TAF. WILL HAVE CONSIDERABLE MID
AND HIGH LVL CLOUDS THRU THE DAY WITH CEILINGS LOWERING TO 8000 FT
BY EARLY AFTN. THE NAM AND RAP HAVE LOWER CEILINGS DOWN TO 5000 FT
OR SO BY AFTN BUT WILL KEEP THEM AROUND 8000 FT FOR NOW. AS FOR
WINDS A SFC LOW HS FORMED EARLY THIS MORNING NR DENVER WITH LIGHT
WLY WINDS AT THE AIRPORT. THE LATEST RAP KEEPS THIS LOW NR DENVER
THRU AFTN WITH VARIABLE WIND DIRECTIONS. FOR NOW WILL HAVE THEM
TRENDING LIGHT ELY BY LATE MORNING THRU MID AFTN AND THEN BECOMING
MORE NLY BY 00Z. BY EARLY EVENING WILL HAVE NWLY WINDS FOR A FEW
HOURS AND THEN MORE WSW BY 06Z.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....BAKER
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DES MOINES IA
300 PM CST FRI DEC 14 2012
.SHORT TERM /TONIGHT/...
FAIRLY STRAIGHTFORWARD FORECAST WITH THE UPCOMING SYSTEM THAT WILL
IMPACT THE REGION TONIGHT. SHARP NEGATIVELY TILTED 300 MB SHORTWAVE
OVER THE FOUR CORNERS REGION HAS BEGUN EJECTING NORTHEASTWARD AND
ACCELERATING TOWARDS THE UPPER MIDWEST THIS AFTERNOON. OVER THE LAST
24 HOURS...THIS WAVE...WHICH ORIGINATED IN THE POLAR JET...HAS
PHASED WITH THE SUBTROPICAL JET OVER THE BAJA PENINSULA AND HELPED
PULL PACIFIC MOISTURE NORTHEASTWARD INTO THE UPPER MIDWEST. THIS IS
WELL DEPICTED ON CURRENT WATER VAPOR SATELLITE IMAGERY. CIRROSTRATUS
ASSOCIATED WITH THIS MOISTURE PLUME HAS ALREADY REACHED CENTRAL
IOWA...BUT DID LITTLE TO STOP TEMPERATURES FROM SOARING WELL ABOVE
NORMAL INTO THE LOW TO MID 50S ACROSS THE CWA.
AN ADDITIONAL SHORTWAVE DROPPING SOUTH ALONG THE US WEST COAST WILL
AID IN USHERING THE AFOREMENTIONED SYSTEM INTO THE UPPER MIDWEST
TONIGHT. LEE CYCLOGENESIS ALONG THE FRONT RANGE WILL RESULT IN A
998MB SURFACE CYCLONE DEVELOPING BY 00Z IN EASTERN COLORADO THAT
WILL PROGRESS EAST NORTHEASTWARD INTO EASTERN NEBRASKA BY 12Z
SATURDAY MORNING. SIGNIFICANT MOISTURE ADVECTION FROM THE WESTERN
GULF WILL RESULT IN +2 STANDARD DEVIATION PWATS OF 0.75 INCHES TO
NEARLY AN INCH OVER IOWA (COMPARED TO THE DVN RAOB SITE) BY 06Z
TONIGHT. THIS LOW LEVEL GULF MOISTURE...COMBINED WITH THE UPPER
LEVEL MOISTURE FROM THE PACIFIC...WILL PRIME THE ATMOSPHERIC COLUMN
FOR A SIGNIFICANT RAINFALL EVENT. EXTENSIVE MID TO UPPER LEVEL
FORCING ASSOCIATED WITH THE UPPER LEVEL SYSTEM WILL BE THE MAIN
DRIVER FOR PRECIPITATION OVERNIGHT. THIS IS DEPICTED WELL IN THE
STRONG Q-VECTOR CONVERGENCE FIELDS FROM 500-300MB AND THE RESULTANT
OMEGA CROSS SECTIONS WHICH SHOW DEEP AND WIDESPREAD LIFT FROM 700 TO
300 MB OVER CENTRAL IOWA BETWEEN 06 AND 12Z.
MID TO LOW LEVEL FRONTOGENESIS IS ALSO PRESENT FROM 700 TO 800 MB
DURING THIS TIME AND MAY LEAD TO SOME LOCALIZED BANDS OF ENHANCED
RAINFALL. GIVEN THE FAST PROGRESSION OF THE SYSTEM...HAVE OPTED TO
MAKE MINIMAL CHANGES TO THE STORM TOTAL QPF FORECAST OF 0.60 TO 0.70
INCHES OF RAIN FOR THE CWA. THE INGREDIENTS ARE ALL IN PLACE...BUT
ONLY FOR A SHORT PERIOD. SOME ELEVATED CONVECTIVE INSTABILITY
RESULTING FROM STEEPING MID-LEVEL LAPSE RATES COULD BE ENOUGH TO
GENERATE A FEW THUNDERSTORMS OVER SOUTHERN IOWA...SO CONTINUED
ISOLATED THUNDER WORDING IN THE GRIDS SOUTH OF I-80.
TEMPERATURES ALSO PROVED TO BE A BIT OF A CHALLENGE DUE TO THE WARM
FRONT THAT WAS OVER CENTRAL IOWA OVERNIGHT LIFTING FURTHER NORTH
THAN PREVIOUSLY ANTICIPATED...RESULTING IN WARMER READINGS ACROSS
THE NORTHERN CWA. THE RUC AND NAM DNG DID A GOOD JOB THIS MORNING
DEPICTING THE FASTER WARM FRONT PROGRESSION AND WARMER
TEMPERATURES...SO LEANED TOWARDS THESE TWO MODELS WITH OVERNIGHT
LOWS. THIS RESULTED IN LITTLE CHANGE TO THE SOUTHERN HALF OF THE CWA
BUT RAISED TEMPERATURES 2 TO 3 DEGREES IN THE NORTH. WENT WITH A
NON-DIURNAL COOLING TREND FOR OVERNIGHT TEMPERATURES GIVEN THE
WIDESPREAD CLOUDS..RAIN...AND CONTINUED SOUTHERLY WARM AIR ADVECTION.
.LONG TERM /SATURDAY THROUGH FRIDAY/...
FAIRLY ACTIVE WEATHER PATTERN FOR THE NEXT WEEK ACROSS THE CENTRAL
UNITED STATES. LOOKS LIKE TWO WEATHER SYSTEMS MAY PRODUCE
PRECIPITATION OVER CENTRAL IOWA. THE FIRST SYSTEM...TONIGHT AND
SATURDAY...WILL CERTAINLY PRODUCE WIDESPREAD RAIN. THE SECOND
SYSTEM MAY PRODUCE MORE WINTERLIKE WEATHER.
IN THE BIG PICTURE...SHORT RANGE MODELS ARE IN GOOD AGREEMENT
EJECTING AN UPPER LOW ACROSS THE STATE SATURDAY. EXTENSIVE BAND OF
RAIN SHOULD MOVE THROUGH NORTHERN IOWA SATURDAY MORNING IN RESPONSE
TO IMPRESSIVE UPPER LEVEL DYNAMICS AND MOISTURE ADVECTION. THE RAIN
BAND SHOULD EXIT THE FORECAST AREA DURING THE MORNING WHILE THE
SURFACE LOW MOVES OVER THE STATE. DON/T EXPECT MUCH RAINFALL AFTER
THE INITIAL PRECIPITATION BAND MOVES THROUGH...BUT THERE WILL BE
SOME RESIDUAL LIGHT RAIN LEFT BEHIND ON SATURDAY. SECONDARY PIECE OF
SHORTWAVE ENERGY MOVES THROUGH SATURDAY PROVIDING A PERIOD OF BRIEF
FORCING. HOWEVER...GIVEN THE SPEED OF THIS FEATURE...DO NOT EXPECT
MUCH SENSIBLE WEATHER.
FROM SUNDAY THROUGH TUESDAY...A BROAD UPPER TROUGH ESTABLISHES
ITSELF OVER THE CENTRAL CONUS ON SUNDAY. THE TROUGH APPEARS TO BE
PROGRESSIVE WHICH SEEMS REASONABLE GIVEN THE RECENT PATTERN. THE
NEXT SIGNIFICANT UPPER TROUGH IN FLOW IS FORECAST TO IMPACT THE
CENTRAL US MIDWEEK. THE 12Z ECMWF IS SLOWER AND MORE AMPLIFIED WITH
THIS TROUGH AND DEVELOPS A 500 MB LOW OVER THE AREA BY THURSDAY
MORNING. IN TURN...IT QUICKLY DEEPENS A SURFACE AND TRACKS IT
THROUGH MISSOURI AND INTO ILLINOIS. THIS IS A FAVORABLE TRACK FOR A
SNOW EVENT IN CENTRAL IOWA AND THIS SYSTEM WILL NEED TO BE
MONITORED. HOWEVER...THE GFS KEEPS THE WAVE OPEN AND MORE
PROGRESSIVE THUS LESS PRECIPITATION. IT DOES PRODUCE SNOW OVER THE
FORECAST AREA WEDNESDAY NIGHT. THIS SYSTEM APPEARS TO HAVE A DECENT
BAROCLINIC ZONE OVER THE PLAINS AND MIDWEST TO WORK WITH. AS FOR THE
FORECAST...HAVE SNOW POPS GOING WEDNESDAY NIGHT THURSDAY.
CONCERNING TEMPERATURES...NO DEEP INTRUSION OF COLD AIR IS EXPECTED
AFTER THE SYSTEM THIS WEEKEND. HOWEVER...MORE COLD AIR COULD BE
DRAWN INTO CENTRAL AFTER THE SYSTEM NEXT WEEK DEPENDING ON HOW
AMPLIFIED IT GETS.
&&
.AVIATION...14/18Z
VFR CONDITIONS ARE EXPECTED THROUGH TODAY WITH SOUTHERLY
WINDS INCREASING THIS AFTERNOON AS THE NEXT WEATHER SYSTEM
APPROACHES FROM THE SOUTHWEST. CEILINGS WILL LOWER THROUGHOUT THE
EVENING BUT SHOULD REMAIN VFR UNTIL AROUND MIDNIGHT WHEN WIDESPREAD
RAIN MOVES INTO THE STATE. CURRENTLY HAVE ONLY LOWERED CEILINGS AND
VISIBILITIES AT MOST SITES TO LOW MVFR...BUT LIKELY ANTICIPATE IFR
CONDITIONS AT TIMES DURING THE EVENT. THE RAIN BEGINS TO PULL OUT BY
MID MORNING TOMORROW BUT LOW STRATUS LOOKS TO REMAIN IN PLACE
THROUGH MUCH OF THE DAY.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...KS
AVIATION...KS
LONG TERM...JOHNSON
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
308 PM CST FRI DEC 14 2012
.SYNOPSIS...
12Z UA ANALYSIS HAS SEVERAL WEAK TROFS FROM THE MID MISSISSIPPI
VALLEY BACK INTO NORTHERN MEXICO. A PLUME OF MOISTURE WAS STREAMING
NORTH ON A LLJ FROM TEXAS INTO SOUTHERN KANSAS. SATELLITE DATA
SHOWED PLENTY OF MID AND HIGH LEVEL CLOUDS STREAMING NORTHEAST
THROUGH THE PLAINS WITH LOW CLOUDS AS FAR NORTH AS EASTERN KANSAS
AND CENTRAL MISSOURI. RADARS SHOW PRECIPITATION IS BREAKING OUT OVER
MORE OF THE PLAINS.
18Z SFC ANALYSIS HAD A DEVELOPING WARM FRONT RUNNING FROM THE
NEBRASKA/SOUTH DAKOTA BORDER EAST INTO NORTHERN INDIANA. DEW POINTS
WERE GENERALLY IN THE 20S ACROSS THE MIDWEST BUT A PLUME OF HIGHER
DEW POINTS RAN FROM TEXAS INTO KANSAS AND EASTERN NEBRASKA.
&&
.SHORT TERM...TONIGHT AND SATURDAY...
THE QUESTION IS NOT IF IT WILL RAIN BUT WHEN.
INITIALLY THERE IS A DRY ATMOSPHERE ACROSS THE AREA THAT WILL NEED
TO SATURATE BEFORE PRECIPITATION BEGINS. TRENDS FROM THE RAP AND
OTHER MODELS GENERALLY AGREE THAT SATURATION WILL OCCUR FAIRLY
QUICKLY DURING THE EVENING HOURS.
THE RAP TRENDS INDICATE CONDENSATION PRESSURE DEFICITS IN THE
850-700MB LAYER WILL COLLAPSE DURING THE EVENING HOURS BUT REMAIN
HIGH IN THE 1000-850MB LAYER. THE OVERALL FORCING INCREASES DURING
THIS TIME WITH F VECTOR CONVERGENCE ALSO DEVELOPING. THUS WHILE THE
AREA WILL START OUT DRY...BY MID EVENING ISOLD SHRA SHOULD BREAK OUT
ACROSS THE SOUTHWEST THIRD OF THE CWFA WITH SPRINKLES POSSIBLE OVER
ALL BUT THE FAR NORTH/NORTHEAST PARTS OF THE CWFA. BY MIDNIGHT
CONDENSATION PRESSURE DEFICITS IN THE 1000-850MB LAYER COLLAPSE SO
SHRA WILL RAPIDLY BECOME MORE NUMEROUS.
AFTER MIDNIGHT...NEARLY ALL THE MODELS SHOW A SIGNIFICANT WING OF
ISENTROPIC LIFT MOVING THROUGH WITH WAA PRECIPITATION. THE LIFT TOOL
SHOWS A SIGNIFICANT THETA E GRADIENT MOVING THROUGH THE CWFA BUT THE
INFERRED TRIPLE POINT SHOULD MOVE FROM KUIN TO KPIA. THUS THE
PRECIPITATION SHOULD STRATIFORM OUT ACROSS THE CWFA AFTER MIDNIGHT.
ANY CONVECTION WITH TSRA SHOULD REMAIN TO THE SOUTH AND EAST OF THE
CWFA.
SATURDAY MORNING THE WAA WING OF ISENTROPIC LIFT MOVES OUT OF THE
CWFA ALLOWING A DECREASE IN THE OVERALL INTENSITY OF THE RAINFALL.
THE DRY SLOT IS PROGGED TO MOVE INTO THE CWFA DURING THE MORNING BUT
FCST SOUNDINGS SHOW CONSIDERABLE LOW LEVEL MOISTURE BELOW IT. THUS
THE DRY SLOT LOOKS TO BE DIRTY WITH PLENTY OF CLOUDS WITH
PRECIPITATION BECOMING MORE SHOWERY BY LATE MORNING AND AFTERNOON.
THE UNSEASONABLY WARM TEMPERATURES WILL CONTINUE WITH MAX
TEMPERATURES WELL ABOVE NORMAL.
OVERALL...GIVEN THE SPEED OF THE SYSTEM...IT APPEARS THAT A GENERAL
RAINFALL OF AROUND ONE HALF INCH SHOULD OCCUR WITH THIS STORM
SYSTEM. ..08..
.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY...
SATURDAY NIGHT AND SUNDAY THE MAIN FOCUS IS ON THE EXITING SYSTEM
OFF TO THE NORTHEAST. SATURDAY NIGHT WE SHOULD HAVE A SECONDARY
WAVE AND A TROWAL LIKE FEATURE MOVE ACROSS EASTERN IOWA AND NORTHERN
ILLINOIS IN THE WAKE OF THE MAIN FEATURE TONIGHT AND SATURDAY.
LINGERING LOW AND MID LEVEL MOISTURE SHOULD ALLOW THIS FEATURE TO
PRODUCE SOME RAIN SHOWERS CONTINUING INTO SUNDAY MORNING BEFORE IT
FINALLY MOVES OFF TO THE EAST. THIS WILL BE VERY COLD RAIN...AND
ONLY A SMALL CHANGE IN THE THERMAL PARAMETERS COULD CAUSE SOME
MIXTURE WITH SNOW OR SLEET...BUT THIS LOOKS UNLIKELY FOR NOW.
TEMPERATURES THROUGH THE PERIOD TO CONTINUE TO FALL WITH HIGHS ON
SUNDAY RANGING FROM AROUND 40 NORTHWEST TO THE MID 40S.
MONDAY ANOTHER UPPER LEVEL TROUGH AXIS WILL MOVE ACROSS THE
MIDWEST...BUT THE VORT MAXIMUM WILL MOVE ACROSS SOUTHERN
MISSOURI...AND WE WILL MISS ANY PRECIPITATION FROM THIS WAVE.
HOWEVER...THIS WILL KEEP THE COLDER AIR OVER THE REGION AND HIGHS ON
MONDAY WILL ONLY BE IN THE MID 30S TO LOW 40S. THIS IS STILL ABOVE
NORMAL...SO COLDER IS A RELATIVE TERM.
WARM AIR ADVECTION AND RETURN FLOW SETS IN THEN FOR TUESDAY AND MOST
OF WEDNESDAY...WITH HIGHS BY WEDNESDAY IN THE 40S NEARLY EVERYWHERE.
MODELS ARE DEPICTING A STORM SYSTEM MOVING ACROSS THE MIDWEST DURING
THE MIDDLE OF THE WEEK...CURRENTLY SET TO AFFECT THE FORECAST AREA
WEDNESDAY NIGHT AND THURSDAY. THERE HAS BEEN A LOT OF VARIABILITY
WITH THIS STORM...BOTH IN THE AMOUNT OF PHASING AS THE UPPER LEVEL
TROUGH AXIS COMES ACROSS THE MIDWEST...AND IN THE STRENGTH AND
TIMING OF THE FEATURE. THUS...THE CONSENSUS FORECAST STILL SEEMS
LIKE THE BEST SOLUTION FOR NOW AND HAVE MAINTAINED THE CHANCE POPS
GOING FOR THAT PERIOD...FOLLOWED BY ANOTHER SHOT OF RELATIVELY
COLDER AIR FOR FRIDAY. BY THE SOLSTICE NEXT FRIDAY...WE MIGHT
ACTUALLY HAVE TEMPERATURES NEAR NORMAL. LE
&&
.AVIATION.../ISSUED 1134 AM CST THU DEC 14 2012/
VFR WX WILL BE SEEN THROUGH 00Z/15 AS A FRONT MOVES NORTH INTO
MINNESOTA AND WISCONSIN. AFT 00Z/15 CONDITIONS WILL INITIALLY
DETERIORATE SLOWLY BUT THEN RAPIDLY DETERIORATE TO MVFR CONDITIONS
AFT 04Z/15 WITH POSSIBLE IFR CONDITIONS PRIOR TO SUNRISE DEC 15TH.
MVFR/IFR CONDITIONS ARE EXPECTED TO PERSIST PAST 12Z/15. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
08/LE
AREA FORECAST DISCUSSION
NWS TOPEKA KS
305 PM CST FRI DEC 14 2012
.DISCUSSION...
SHORT TERM (TONIGHT THROUGH SATURDAY)...
AN UPPER LEVEL TROUGH...CURRENTLY OVER EASTERN AZ AT 19Z...WILL LIFT
NORTHEAST ACROSS THE STATE OF KS TONIGHT...THEN NORTHEAST INTO
SOUTHERN WI BY LATE SATURDAY AFTERNOON.
AS THE UPPER LEVEL TROUGH APPROACHES SOUTHWEST KS THIS EVENING THE
STRONGER ASCENT AHEAD OF THE H5 TROUGH WILL SPREAD NORTHEAST ACROSS
THE STATE AND WILL CAUSE SHOWERS AND PERHAPS SOME ISOLATED
THUNDERSTORMS TO DEVELOP ACROSS CENTRAL AND SOUTHERN KS LATE THIS
AFTERNOON...THEN SPREAD NORTHEAST ACROSS THE CWA TONIGHT. THE FIRST
BAND OF LIGHT RAIN WAS DEVELOPING FROM DDC TO ENID...OK AND EXTENDED
NORTHEAST TO ICT. THIS AREA OF RAIN WILL REACH THE SOUTHWEST
COUNTIES OF THE CWA BY 5 TO 6 PM CST...AND THEN CONTINUE TO DEVELOP
NORTHEAST AS LOW-LEVEL WAA/ISENTROPIC LIFT INCREASES AND THE
STRONGER ASCENT AHEAD OF THE H5 TROUGH AXIS SHIFTS NORTHEAST ACROSS
EASTERN KS.
EXPECT PERIODS OF LIGHT RAIN AND RAIN SHOWERS TO CONTINUE THROUGH
THE NIGHT. THE NAM AND HRRR MODEL CONTINUE TO SHOW 100-250 J/KG OF
MUCAPE DEVELOPING ACROSS EASTERN KS FROM 0Z THROUGH ABOUT 8Z...THUS
WE COULD SEE ISOLATED ELEVATED THUNDERSTORMS TO DEVELOP THROUGH THE
EVENING HOURS. EVEN THOUGH THE VERTICAL WINDSHEAR WILL BE STRONG THE
INSTABILITY WILL BE WEAK ENOUGH SO THAT ANY ELEVATED THUNDERSTORMS
THAT MANAGE TO DEVELOP WILL PROBABLY NOT BE INTENSE ENOUGH TO
PRODUCE HAIL. MOST AREAS OF THE CWA SHOULD RECEIVE ABOUT THREE TENTH
OF AN INCH OF RAIN WITH SOME AREAS GETTING CLOSE TO A HALF OF AN
INCH.
AFTER 9Z...THE UPPER LEVEL TROUGH WILL MOVE INTO NORTHEAST KS. THE
700MB DRY SLOT WILL MOVE NORTHEAST ACROSS MUCH OF THE EASTERN HALF
OF THE CWA. THUS...MOST OF THE MEASURABLE RAIN ACROSS THE EASTERN
CWA WILL SHIFT NORTHEAST MO. A WEAK TROWAL WILL DEVELOP ACROSS
SOUTHWEST AND CENTRAL KS AND TRANSLATE NORTHEASTWARD ACROSS NORTH
CENTRAL KS...KEEPING THE LIGHT RAIN GOING FOR THE WESTERN AND
EXTREME NORTHEAST COUNTIES THROUGH THE EARLY MORNING HOURS. AS THE
H5 TROUGH AXIS LIFTS NORTHEAST INTO CENTRAL IA...THE WRAP AROUND
MOISTURE WILL SHIFT NORTHEAST INTO EASTERN NE AND WESTERN IA DURING
THE MID MORNING HOURS.
THERE MAY BE SOME BREAKS IN THE CLOUDS DURING THE LATE MORNING AND
EARLY AFTERNOON HOURS. A LESS AMPLIFIED UPPER LEVEL TROUGH WILL MOVE
EAST FROM THE FOUR CORNERS REGION INTO THE CENTRAL HIGH PLAINS. THIS
TROUGH WILL PROVIDE STRONG ENOUGH ASCENT FOR THE CLOUDS TO INCREASE
ACROSS THE CWA DURING THE AFTERNOON HOURS.
HIGHS ON SATURDAY WILL DEPEND ON HOW MUCH INSOLATION WE WILL
RECEIVE. I EXPECT MOSTLY CLOUDY SKIES THROUGH THE DAY WITH HIGH
TEMPERATURES IN THE LOWER TO MID 50S...THOUGH IF WE SEE MORE
INSOLATION IN THE EARLY AFTERNOON THEN HIGHS MAY BE A FEW DEGREES
HIGHER.
GARGAN
&&
.LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)...
A SECONDARY UPPER TROUGH WILL MOVE ACROSS THE NORTHERN AND CENTRAL
PLAINS. MOISTURE IS LIMITED WITH THIS SYSTEM AND FORCING IS MOST
PRONOUNCED 00Z-06Z ACROSS NORTHERN KANSAS. WILL CONTINUE TO MENTION
SOME SPRINKLES SATURDAY EVENING. LOWS SUNDAY MORNING WILL RANGE FROM
THE MID 20S NORTH CENTRAL TO THE LOWER 30S SOUTHEAST.
ANOTHER SHORTWAVE TROUGH WILL MOVE THROUGH SUNDAY NIGHT AND MONDAY.
MOISTURE IS MEAGER AND FORCING AND MOISTURE ARE BETTER TO THE EAST
OF THE FORECAST AREA. THIS WILL BE FOLLOWED BY MIDLEVEL RIDGE
BUILDING OVER THE PLAINS AS A LONG WAVE TROUGH MOVES INTO THE
WESTERN STATES FROM THE EASTERN PACIFIC. TEMPERATURES WILL BE NEAR
TO ABOVE NORMAL SUNDAY THROUGH TUESDAY.
OPERATIONAL MEDIUM RANGE MODELS AND ENSEMBLES MOVE A COLD UPPER LOW
ACROSS THE CENTRAL PLAINS WEDNESDAY NIGHT AND EARLY THURSDAY.
FORECAST SOUNDINGS INDICATE THAT THERE WILL BE SATURATION IN THE
SNOW GROWTH REGION ON THE SOUNDINGS. HAVE INSERTED A SMALL
PROBABILITY OF LIGHT SNOW FOR WEDNESDAY NIGHT AND EARLY TUESDAY. DRY
ON FRIDAY WITH LARGE SCALE SUBSIDENCE WITH DRY NORTHWEST FLOW. HIGHS
ON FRIDAY NEAR NORMAL IN THE LOW TO MID 40S.
53
&&
.AVIATION...
CLOUDS BEGINNING TO BUILD IN FROM THE SOUTH AHEAD OF THE NEXT SYSTEM
REACHING THE TAF SITES BY EARLY THIS AFTERNOON. STILL ON TRACK FOR
WIDESPREAD SHOWERS WHICH WILL DEVELOP LATER THIS EVENING AS THE MID
LEVEL SYSTEM AND ASSOCIATED FORCING PASSES OVER THE REGION CAUSING
MVFR CIGS AND VSBY ONCE THE PRECIP MOVES IN. THERE IS STILL A
POTENTIAL FOR ISOLATED THUNDER GIVEN THE POSSIBILITY OF SOME WEAK
INSTABILITY ALTHOUGH CONFIDENCE IS LOW ATTM TO INCLUDE IN TAFS.
DEPENDING ON THE INTENSITY OF THE RAINFALL THERE MAY BE TEMPORARY
IFR CIGS AND VSBY BUT WILL ALLOW LATER SHIFTS EVALUATE AS THE EVENT
IS CLOSER.
SANDERS
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
250 PM CST FRI DEC 14 2012
.SHORT TERM...(THIS EVENING THROUGH TOMORROW)
ISSUED AT 246 PM CST FRI DEC 14 2012
THE MAIN FORECAST CHALLENGES ARE RAIN CHANCES INTO THIS EVENING.
A STRONG, PROGRESSIVE, AND NEGATIVELY TILTED SHORTWAVE TROUGH IS ON
TRACK BY MODELS TO QUICKLY LIFT NORTHEASTWARD FROM EASTERN COLORADO
AND THE TEXAS PANHANDLE TONIGHT, AND INTO EASTERN KANSAS AND
OKLAHOMA BY MIDNIGHT. LIGHT RAIN SHOWERS AND AN ISOLATED
THUNDERSTORM OR TWO WILL CONTINUE TO DEVELOP INTO THE AFTERNOON,
THEN INCREASE IN AREAL COVERAGE BY 5 TO 6 PM AS THE BEST DYNAMIC
LIFT ASSOCIATED WITH THE UPPER TROUGH MOVES INTO WESTERN KANSAS.
WILL CARRY LIKELY CHANCES FOR RAIN UNTIL THE SHORTWAVE LIFTS RAPIDLY
NORTHEASTWARD OUT OF WESTERN KANSAS. THE PRECIPITATION SHOULD END BY
AROUND 9 PM FROM SCOTT CITY TO NEAR DODGE CITY AND MEADE THEN BY
AROUND MIDNIGHT IN THE HAYS AREA. RAINFALL AMOUNTS COULD RANGE FROM
.10 TO .25 INCHES. THE 16Z HRRR MODEL SHOWING AROUND AN INCH
POSSIBLE IN THE STRONGEST SHOWERS AND THUNDERSTORMS, BUT THINKING
THAT COULD BE VERY LOCALIZED AND A BIT OVERDONE. SKIES WILL CLEAR
RAPIDLY FROM WEST TO EAST BEHIND THE SYSTEM AND SOUTH TO
SOUTHEASTERLY WINDS WILL BECOME SOUTHWEST TO WESTERLY BY MORNING.
SURFACE LOW PRESSURE WILL MOVE OUT OF COLORADO AND INTO EXTREME
NORTH CENTRAL KANSAS AFTER MIDNIGHT. THE WINDS WILL STAY ON THE
BREEZY SIDE FROM 15 TO 25 MPH. OVERNIGHT LOWS WILL BE FAIRLY MILD
WITH GOOD MIXING MUCH OF THE NIGHT AND RANGE FROM THE LOWER TO
MID 30S.
FOR SATURDAY A SECONDARY WEAKER UPPER LEVEL SHORTWAVE MOVES ACROSS
WESTERN KANSAS IN THE AFTERNOON WITH MODELS SHOWING INCREASING MID
LEVEL CLOUDS, BUT NO PRECIPITATION. A TRAILING WEAK TROUGH OF
SURFACE LOW PRESSURE WILL BE FOUND ACROSS THE CENTRAL PLAINS. HIGHS
WILL BE IN THE LOW TO MID 50S AND THESE NUMBERS LOOK CLOSE TO
GUIDANCE.
.LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 222 PM CST FRI DEC 14 2012
SATURDAY NIGHT:
A WEAK UPPER LEVEL WAVE IS EXPECTED TO TRAVERSE ACROSS WESTERN
KANSAS SATURDAY EVENING. SOME OF THE MODELS, SUCH AS THE GFS, ARE
INDICATING LIGHT QPF ACROSS SW KANSAS SATURDAY EVENING. THIS
ACTIVITY IS PROBABLY IN RESPONSE TO THE AFOREMENTIONED UL DISTURBANCE.
FORECAST SOUNDINGS ACROSS THE REGION SHOW THAT THIS MOISTURE IS
ABOVE 700 HPA AND THAT THE LOWER LEVELS ARE DRY AND MIXED. AS A
RESULT, WILL CONTINUE WITH SILENT CHANCES OF PRECIPITATION IN THE
GRIDS. LATER SHIFTS COULD ADD FLURRIES AND/OR SPRINKLES LATER, BUT
I DO NOT HAVE ENOUGH CONFIDENCE TO ADD THIS IN ATTM GIVEN THE VERY
DRY LOW LEVELS. OTHERWISE, OVERNIGHT LOWS IN THE 20S AND 30S DEG F
ARE EXPECTED THROUGH THE OVERNIGHT HOURS.
SUNDAY:
AN UPPER LEVEL SHORTWAVE TROF WILL MOVE ACROSS WESTERN KANSAS
SUNDAY. THIS FEATURE WILL USHER THE PASSAGE OF A WEAK SURFACE COLD
FRONT. WEAK TEMPERATURE ADVECTION IS EXPECTED WITH THIS FRONT. THE
NET RESULT WILL BE COOLER TEMPERATURES - GENERALLY IN THE UPPER
40S DEG F. NO PRECIPITATION IS EXPECTED WITH THE FRONT.
MONDAY AND BEYOND:
HAVE WARMED TEMPERATURES MONDAY AS A DOWNSLOPE FLOW IS EXPECTED
ACROSS SW KANSAS WITH 850 HPA TEMPERATURES WARMING TO AROUND 5 DEG
C. BOTH GFS AND ECMWF MOS GUIDANCE ALSO SUPPORT WARMER
TEMPERATURES WITH VALUES PEAKING IN THE LOWER 50S DEG F. ON
TUESDAY, UPPER LEVEL RIDGING IS EXPECTED ACROSS THE CENTRAL PLAINS WITH
A STRENGTHENING LEE SURFACE TROF ACROSS EASTERN COLORADO. THIS
WILL RESULT IN ABOVE AVERAGE TEMPS WITH VALUES IN THE MID 50S DEG
F. THE FORECAST WILL CONTINUE TO REMAIN DRY.
THE NEXT ITEM OF INTEREST IS FOR THURSDAY AS THE 14.12Z ECMWF/GFS
INDICATE A FAIRLY STRONG COLD FRONT TRAVERSING ACROSS THE KANSAS.
THE MAIN IMPACTS FROM THE FRONT IS WINDY CONDITIONS AND COOLER
TEMPERATURES. THERE COULD BE SOME FLURRIES WITH THIS FRONT IN
ASSOCIATION WITH AN ENHANCED AREA OF 700 HPA OMEGA. DUE TO RECENT
POOR PERFORMANCE OF THE MODELS RECENTLY, WILL CONTINUE WITH A DRY
FORECAST AS CONFIDENCE IS VERY LOW. OFFSHORE FLOW IS EXPECTED ACROSS
THE GULF OF MEXICO DURING THE TUESDAY AND WEDNESDAY TIME FRAME.
THIS SHOULD PREVENT SIGNIFICANT MOISTURE FROM RETURNING TO KANSAS.
BEYOND THURSDAY, THE GFS/ECMWF ARE IN FAIRLY AGREEMENT WITH UPPER
LEVEL RIDGING ACROSS THE ROCKIES. THE RESULTANT NW FLOW ALOFT
ACROSS WESTERN KANSAS IS NOT CONDUCIVE FOR SIGNIFICANT
PRECIPITATION. TEMPERATURES WILL CONTINUE TO REMAIN NEAR TO ABOVE
AVERAGE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1114 AM CST FRI DEC 14 2012
CIGS WILL CONTINUE TO LOWER FROM OVC100 TO MVFR THIS AFTERNOON
WITH SOME LIGHT SHOWERS OR ISOLATED THUNDERSTORMS DEVELOPING
AROUND 22-00Z. A STRONG UPPER LEVEL SHORTWAVE TROUGH WILL MOVE
ACROSS WESTERN KANSAS THIS EVENING ENDING THE LIGHT RAIN SHOWERS
AND ISOLATED THUNDERSTORMS BY 03Z AT KGCK AND KDDC, AND AROUND 06Z
AT KHYS WITH CIGS RAPIDLY IMPROVING TO VFR. SOUTH TO SOUTHEASTERLY
WINDS OF 15-25KT WILL BECOME SOUTHWESTERLY TO WESTERLY TONIGHT AT
12-22KT AS A SURFACE LOW MOVES EAST INTO NORTH CENTRAL KANSAS.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 35 55 29 48 / 70 0 10 10
GCK 33 54 27 47 / 60 0 10 10
EHA 33 56 29 49 / 50 0 10 10
LBL 35 57 30 49 / 70 0 10 10
HYS 35 53 26 47 / 70 0 10 10
P28 38 60 32 51 / 60 0 0 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...KRUSE
LONG TERM...SUGDEN
AVIATION...KRUSE
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1147 AM MST FRI DEC 14 2012
UPDATE ISSUED AT 1147 AM MST FRI DEC 14 2012
LIGHT RAIN HAS BEGUN REACHING THE GROUND ACROSS PORTIONS OF KIT
CARSON AND YUMA COUNTY COLORADO. GRIDS HAVE BEEN UPDATED TO
REFLECT CURRENT TRENDS. SCATTERED ECHOES HAVE ALSO BEGUN TO
INCREASE ACROSS THE REST OF THE CWA AND EXPECT PRECIPITATION TO
INCREASE OVER THE NEXT FEW HOURS. WARM FRONT HAS FINALLY BEGUN TO
NUDGE INTO THE SOUTHERN COUNTIES OF CWA INCREASING TEMPERATURES
AND WILL GRADUALLY RAISE DEWPOINTS INTO THE 30S THROUGH THE
AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 342 AM MST FRI DEC 14 2012
MAIN FORECAST CONCERN WILL BE STORM SYSTEM THAT WILL IMPACT THE AREA
THROUGH TONIGHT. SATELLITE SHOWING A PROGRESSIVE NEARLY ZONAL FLOW
FROM THE PACIFIC INTO THE WESTERN ATLANTIC. THE EXCEPTION TO THIS
IS THE SYSTEM THAT IS CUT OFF FROM THE FLOW AND EXTENDS FROM NEVADA
TO JUST OFF THE SOUTHERN CALIFORNIA COAST. THROUGH 05Z THIS SYSTEM
WAS STILL DIGGING AND NOT MAKING ANY PROGRESS EAST YET. THIS TROUGH
HAS PULLED UP SUBTROPICAL MOISTURE AHEAD OF IT.
AT JET LEVEL...THE NAM...UKMET AND SREF LOOK TO HAVE THE JET SEGMENT
COMING IN FROM THE SOUTHWEST THE BEST. OTHER MODELS TENDED TO HAVE
THE HIGHER SPEEDS TOO FAR NORTH OR EAST. AT MID LEVELS...WITH THE
INCOMING UPPER TROUGH...MODELS TENDED TO BE TOO FAR SOUTH AND EAST.
THE GFS AND CANADIAN WERE DOING A LITTLE BETTER THAN THE SREF AND
NAM. MODELS ALSO TENDED TO BE TOO GENEROUS WITH THE MID LEVEL
MOISTURE. MODELS ARE HAVING A HARD CATCHING THE SUBTLE COLD FRONT
THAT SAGGED OVER THE AREA TODAY. THE NAM AND RUC WERE DOING THE
BEST. ALSO MODELS ARE TOO GENEROUS WITH LOW LEVEL MOISTURE WITH THE
HIGHER DEWPOINTS TOO FAR NORTH ALREADY. THE GFS AND CANADIAN WERE
DOING THE BEST ON THE LOW LEVEL THERMAL FIELD.
TODAY/TONIGHT...LEFT FRONT QUADRANT OF THE JET CONTINUES TO MOVE
CLOSE TO AREA AND AFFECTS THE AREA MAINLY FROM 12Z TO 18Z. DURING
THAT TIME IT LOOKS LIKE THERE IS NOT A LOT OF LOW LEVEL MOISTURE BUT
LITTLE MOISTURE IN THE COLUMN. SURFACE OBSERVATIONS AND 00Z SOUNDINGS
TO OUR SOUTH ARE VERY DRY. BY THE TIME THE MOISTURE GETS HERE...THE
MAIN JET IS WELL EAST. SPEAKING OF MOISTURE RETURN...DEWPOINTS
REMAIN VERY LOW AND THERE IS NO SIGNIFICANT INCREASE IN MOISTURE
UNTIL WELL SOUTH. MODELS ARE OVERDOING MOISTURE RETURN RIGHT NOW.
00Z SOUNDINGS OVER OUR AREA AND TO THE SOUTH ARE EXTREMELY DRY.
MOISTURE TRAJECTORIES WOULD SUPPORT BEST MOISTURE FURTHER SOUTH AND
EAST. ALSO THUNDERSTORMS WILL BE DEVELOPING TO OUR SOUTH AND EAST
AND SLOW DOWN OR ROB ANY MOISTURE RETURN WE WERE GOING TO SEE.
DUE TO THE SUBTROPICAL MOISTURE RETURN...THERE LOOKS TO BE A
SIGNIFICANT MID/UPPER LEVEL CLOUD DECK WHICH WILL INHIBIT HEATING
AND ANY SURFACE INSTABILITY. MODELS ARE ALSO SHOWING LITTLE TO NO
ELEVATED CAPE AS WELL. WITH MODELS OVERDOING THE INFLUX OF MOISTURE
MODELS ARE PROBABLY OVERDOING ANY INSTABILITY AS WELL. SO CHOSE TO
KEEP THUNDER OUT OF THE FORECAST.
00Z MODEL DATA WAS HINTING AT IT AND NOW 06Z IS CATCHING ONTO IT
EVEN MORE. THE MODELS STILL BRING THE SYSTEM ACROSS IN A NEGATIVE
TILT. HOWEVER...THEY BRING IT ACROSS WITH A NORTHERN AND SOUTHERN
CIRCULATION ON EITHER SIDE OF THE FORECAST AREA. MODELS HAVE BACKED
THEIR IDEA OF ANY WRAP AROUND ON THE BACKSIDE OF THE SYSTEM. PLUS
MODELS HAVE PUSHED EASTERN BAND OF PRECIPITATION FURTHER SOUTH AND
EAST. SO IN A NUTSHELL BEST MOISTURE...LIFT...AND INSTABILITY ARE
NOT INSYNC OR NOT THERE. AT THIS TIME IT STILL DOES LOOK LIKE THE
NORTHEAST PORTION OF THE AREA WILL HAVE THE BEST CHANCE FOR
MEASURABLE PRECIPITATION WITH LITTLE TO NONE FURTHER SOUTHWEST AND
WEST YOU GO.
NEW MODEL GUIDANCE SLOWED THINGS DOWN ON PRECIPITATION ARRIVAL AND
LIMITED POPS TO THE AFTERNOON AND TIERED THEM FROM LOWEST TO HIGHEST
PER REASONING ABOVE. BELIEVE PRECIPITATION WILL SHUT OFF PRETTY QUICK
GIVEN THE SPEED OF THE SYSTEM AND MODEL DEFICIENCIES MENTIONED
ABOVE. BELIEVE MOST OF THE PRECIPITATION WILL BE DOWN BY OR SHORTLY
AFTER 06Z. DID HOLD ONTO PRECIPITATION AFTER THAT JUST KEEP WITHIN
SOME CLOSENESS WITH MY NEIGHBORS. IN REGARDS TO PHASE. LOOKS LIKE IT
STAYS RAIN THROUGH THE DAY. MODEL SOUNDINGS INDICATE TEMPERATURES
STAYING ABOVE FREEZING FOR MOST OF THE NIGHT EVEN IF THERE IS ICE IN
THE COLUMN. SOUNDINGS ARE ALSO NOT OPTIMISTIC ABOUT ICE IN THE
COLUMN EITHER. IT ALSO LOOKS BY THE TIME THE AIR MASS GETS COLD
ENOUGH TO SUPPORT SNOW...THE LIFT AND MOISTURE ARE GONE. SO ONLY
HAVE A MIX OF RAIN AND SNOW AT BEST. THEREFORE THERE SHOULD BE
LITTLE TO NO SNOW ACCUMULATION.
PRIOR TO ARRIVAL OF CLOUDS TEMPERATURES HAVE COOLED OFF
DRAMATICALLY THIS MORNING WITH MODELS TOO WARM. COMBINATION OF
UNFAVORABLE WIND FIELD AND INCREASING CLOUD COVER/DEVELOPING
PRECIPITATION WILL KEEP TEMPERATURES FROM WARMING MUCH. BELIEVE THE
GEM WAS CATCHING THE IDEA THE BEST AND I MAY BE TOO WARM.
SATURDAY/SATURDAY NIGHT...TRICKY MAX TEMPERATURE FORECAST. NORTHWEST
WINDS AND SOME SUN EARLY WILL ALLOW FOR TEMPERATURES TO WARM. BUT
NEXT SHORTWAVE TROUGH WILL DRAMATICALLY INCREASE CLOUD COVER IN THE
AFTERNOON. CHOSE TO TOWARD THE COOLER SIDE. FOR THE NIGHT MODELS
STILL PRODUCING QPF. MODELS DIFFER ON WHERE TO PUT IT BUT GENERALLY
FAVOR THE SOUTHWEST. NOT UNREASONABLE FOR PRECIPITATION TO OCCUR
ANYWHERE BUT AM NOT TOTALLY SOLD ON ANYTHING OCCURRING. SO
BROADBRUSHED LOW SLIGHT CHANCE POPS FOR THE ENTIRE AREA.
SUNDAY/SUNDAY NIGHT...AGAIN LIGHT WIND FIELD AND INCREASING CLOUD
COVER WILL CREATE FOR A TRICKY HIGH TEMPERATURE FORECAST. MODELS
INDICATE A COOLER AIR MASS THAN ON SATURDAY. TRENDED COOLER OR
TOWARD COOLER GUIDANCE.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 342 AM MST FRI DEC 14 2012
AN UPPER LEVEL RIDGE WILL MOVE OVER THE AREA THE FIRST PART OF NEXT
WEEK. FOLLOWING THE RIDGE WILL BE A SHORT WAVE TROUGH...WHICH WILL
APPROACH THE AREA WEDNESDAY. AHEAD OF THE TROUGH THERE MAY BE A
CHANCE FOR SOME PRECIPITATION WEDNESDAY AS A COLD FRONT MOVES
THROUGH. AT THIS TIME MODELS DISAGREE WITH THE TIMING OF THE FRONT
BY AS MUCH AS 12 HOURS. IN ADDITION...LIFT ALONG THE FRONT DOES NOT
LOOK STRONG ENOUGH AT THIS POINT TO DEVELOP ANY PRECIPITATION AND
THE ENVIRONMENT MOISTENS BEHIND THE FRONT WHERE THERE IS ALMOST NO
LIFT. IF MODELS COME INTO A BETTER AGREEMENT WITH THE FRONTAL
PASSAGE...AND IF THE LIFT ALONG THE FRONT WILL STRENGTHEN WITH A
BETTER SUPPLY OF MOISTURE...A MENTION OF PRECIPITATION WILL THEN BE
WARRANTED.
TEMPERATURES FOR THE PERIOD WILL WARM THROUGH WEDNESDAY AHEAD OF THE
COLD FRONT...WITH VALUES 10 TO 15 DEGREES ABOVE NORMAL. AFTER THE
COLD FRONT TEMPERATURES RETURN TO NEAR NORMAL VALUES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1036 AM MST FRI DEC 14 2012
TAFS SEEM TO BE ON TRACK FOR LOWER CIGS AND CHANCE OF LIGHT
PRECIPITATION DEVELOPING AT BOTH TERMINALS THIS AFTERNOON AND
OVERNIGHT. UPPER LEVEL TROUGH IS CURRENTLY MOVING ACROSS THE FOUR
CORNERS REGION AND LIGHT PRECIPITATION IS DEVELOPING AND REACHING
THE SURFACE ACROSS PORTIONS OF EASTERN COLORADO. EXPECT
SCATTERED PRECIPITATION TO DEVELOP AT KGLD AROUND 20-21Z WITH
DEVELOPMENT AT KMCK A BIT LATER AROUND 22-23Z. ATTM KMCK LOOKS TO
BE THE BETTER RECIPIENT FOR MEASURABLE PRECIP WHICH MAY BRING
VSBY DOWN TO MVFR FOR A FEW HOURS TONIGHT. CIGS STILL REMAIN A
TRICKY FORECAST WITH MODELS BRINGING KMCK DOWN TO IFR AND MAYBE A
BRIEF PERIOD OF LIFR OVERNIGHT. UPPER LEVEL SYSTEM WILL BE EAST OF
THE AREA BY 06-08Z WITH SKIES GRADUALLY CLEARING THROUGH THE END
OF THE PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...PMM
SHORT TERM...BULLER
LONG TERM...JTL
AVIATION...PMM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1142 AM MST FRI DEC 14 2012
.UPDATE...
ISSUED AT 1136 AM MST FRI DEC 14 2012
LIGHT RAIN HAS BEGUN REACHING THE GROUND ACROSS PORTIONS OF KIT
CARSON AND YUMA COUNTY COLORADO. GRIDS HAVE BEEN UPDATED TO
REFLECT CURRENT TRENDS. SCATTERED ECHOES HAVE ALSO BEGUN TO
INCREASE ACROSS THE REST OF THE CWA AT EXPECT PRECIPITATION TO
INCREASE OVER THE NEXT FEW HOURS. WARM FRONT HAS FINALLY BEGUN TO
NUDGE INTO THE SOUTHERN COUNTIES OF CWA INCREASING TEMPERATURES
AND WILL GRADUALLY RAISE DEWPOINTS INTO THE 30S THROUGH THE AFTERNOON.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 342 AM MST FRI DEC 14 2012
MAIN FORECAST CONCERN WILL BE STORM SYSTEM THAT WILL IMPACT THE AREA
THROUGH TONIGHT. SATELLITE SHOWING A PROGRESSIVE NEARLY ZONAL FLOW
FROM THE PACIFIC INTO THE WESTERN ATLANTIC. THE EXCEPTION TO THIS
IS THE SYSTEM THAT IS CUT OFF FROM THE FLOW AND EXTENDS FROM NEVADA
TO JUST OFF THE SOUTHERN CALIFORNIA COAST. THROUGH 05Z THIS SYSTEM
WAS STILL DIGGING AND NOT MAKING ANY PROGRESS EAST YET. THIS TROUGH
HAS PULLED UP SUBTROPICAL MOISTURE AHEAD OF IT.
AT JET LEVEL...THE NAM...UKMET AND SREF LOOK TO HAVE THE JET SEGMENT
COMING IN FROM THE SOUTHWEST THE BEST. OTHER MODELS TENDED TO HAVE
THE HIGHER SPEEDS TOO FAR NORTH OR EAST. AT MID LEVELS...WITH THE
INCOMING UPPER TROUGH...MODELS TENDED TO BE TOO FAR SOUTH AND EAST.
THE GFS AND CANADIAN WERE DOING A LITTLE BETTER THAN THE SREF AND
NAM. MODELS ALSO TENDED TO BE TOO GENEROUS WITH THE MID LEVEL
MOISTURE. MODELS ARE HAVING A HARD CATCHING THE SUBTLE COLD FRONT
THAT SAGGED OVER THE AREA TODAY. THE NAM AND RUC WERE DOING THE
BEST. ALSO MODELS ARE TOO GENEROUS WITH LOW LEVEL MOISTURE WITH THE
HIGHER DEWPOINTS TOO FAR NORTH ALREADY. THE GFS AND CANADIAN WERE
DOING THE BEST ON THE LOW LEVEL THERMAL FIELD.
TODAY/TONIGHT...LEFT FRONT QUADRANT OF THE JET CONTINUES TO MOVE
CLOSE TO AREA AND AFFECTS THE AREA MAINLY FROM 12Z TO 18Z. DURING
THAT TIME IT LOOKS LIKE THERE IS NOT A LOT OF LOW LEVEL MOISTURE BUT
LITTLE MOISTURE IN THE COLUMN. SURFACE OBSERVATIONS AND 00Z SOUNDINGS
TO OUR SOUTH ARE VERY DRY. BY THE TIME THE MOISTURE GETS HERE...THE
MAIN JET IS WELL EAST. SPEAKING OF MOISTURE RETURN...DEWPOINTS
REMAIN VERY LOW AND THERE IS NO SIGNIFICANT INCREASE IN MOISTURE
UNTIL WELL SOUTH. MODELS ARE OVERDOING MOISTURE RETURN RIGHT NOW.
00Z SOUNDINGS OVER OUR AREA AND TO THE SOUTH ARE EXTREMELY DRY.
MOISTURE TRAJECTORIES WOULD SUPPORT BEST MOISTURE FURTHER SOUTH AND
EAST. ALSO THUNDERSTORMS WILL BE DEVELOPING TO OUR SOUTH AND EAST
AND SLOW DOWN OR ROB ANY MOISTURE RETURN WE WERE GOING TO SEE.
DUE TO THE SUBTROPICAL MOISTURE RETURN...THERE LOOKS TO BE A
SIGNIFICANT MID/UPPER LEVEL CLOUD DECK WHICH WILL INHIBIT HEATING
AND ANY SURFACE INSTABILITY. MODELS ARE ALSO SHOWING LITTLE TO NO
ELEVATED CAPE AS WELL. WITH MODELS OVERDOING THE INFLUX OF MOISTURE
MODELS ARE PROBABLY OVERDOING ANY INSTABILITY AS WELL. SO CHOSE TO
KEEP THUNDER OUT OF THE FORECAST.
00Z MODEL DATA WAS HINTING AT IT AND NOW 06Z IS CATCHING ONTO IT
EVEN MORE. THE MODELS STILL BRING THE SYSTEM ACROSS IN A NEGATIVE
TILT. HOWEVER...THEY BRING IT ACROSS WITH A NORTHERN AND SOUTHERN
CIRCULATION ON EITHER SIDE OF THE FORECAST AREA. MODELS HAVE BACKED
THEIR IDEA OF ANY WRAP AROUND ON THE BACKSIDE OF THE SYSTEM. PLUS
MODELS HAVE PUSHED EASTERN BAND OF PRECIPITATION FURTHER SOUTH AND
EAST. SO IN A NUTSHELL BEST MOISTURE...LIFT...AND INSTABILITY ARE
NOT INSYNC OR NOT THERE. AT THIS TIME IT STILL DOES LOOK LIKE THE
NORTHEAST PORTION OF THE AREA WILL HAVE THE BEST CHANCE FOR
MEASURABLE PRECIPITATION WITH LITTLE TO NONE FURTHER SOUTHWEST AND
WEST YOU GO.
NEW MODEL GUIDANCE SLOWED THINGS DOWN ON PRECIPITATION ARRIVAL AND
LIMITED POPS TO THE AFTERNOON AND TIERED THEM FROM LOWEST TO HIGHEST
PER REASONING ABOVE. BELIEVE PRECIPITATION WILL SHUT OFF PRETTY QUICK
GIVEN THE SPEED OF THE SYSTEM AND MODEL DEFICIENCIES MENTIONED
ABOVE. BELIEVE MOST OF THE PRECIPITATION WILL BE DOWN BY OR SHORTLY
AFTER 06Z. DID HOLD ONTO PRECIPITATION AFTER THAT JUST KEEP WITHIN
SOME CLOSENESS WITH MY NEIGHBORS. IN REGARDS TO PHASE. LOOKS LIKE IT
STAYS RAIN THROUGH THE DAY. MODEL SOUNDINGS INDICATE TEMPERATURES
STAYING ABOVE FREEZING FOR MOST OF THE NIGHT EVEN IF THERE IS ICE IN
THE COLUMN. SOUNDINGS ARE ALSO NOT OPTIMISTIC ABOUT ICE IN THE
COLUMN EITHER. IT ALSO LOOKS BY THE TIME THE AIR MASS GETS COLD
ENOUGH TO SUPPORT SNOW...THE LIFT AND MOISTURE ARE GONE. SO ONLY
HAVE A MIX OF RAIN AND SNOW AT BEST. THEREFORE THERE SHOULD BE
LITTLE TO NO SNOW ACCUMULATION.
PRIOR TO ARRIVAL OF CLOUDS TEMPERATURES HAVE COOLED OFF
DRAMATICALLY THIS MORNING WITH MODELS TOO WARM. COMBINATION OF
UNFAVORABLE WIND FIELD AND INCREASING CLOUD COVER/DEVELOPING
PRECIPITATION WILL KEEP TEMPERATURES FROM WARMING MUCH. BELIEVE THE
GEM WAS CATCHING THE IDEA THE BEST AND I MAY BE TOO WARM.
SATURDAY/SATURDAY NIGHT...TRICKY MAX TEMPERATURE FORECAST. NORTHWEST
WINDS AND SOME SUN EARLY WILL ALLOW FOR TEMPERATURES TO WARM. BUT
NEXT SHORTWAVE TROUGH WILL DRAMATICALLY INCREASE CLOUD COVER IN THE
AFTERNOON. CHOSE TO TOWARD THE COOLER SIDE. FOR THE NIGHT MODELS
STILL PRODUCING QPF. MODELS DIFFER ON WHERE TO PUT IT BUT GENERALLY
FAVOR THE SOUTHWEST. NOT UNREASONABLE FOR PRECIPITATION TO OCCUR
ANYWHERE BUT AM NOT TOTALLY SOLD ON ANYTHING OCCURRING. SO
BROADBRUSHED LOW SLIGHT CHANCE POPS FOR THE ENTIRE AREA.
SUNDAY/SUNDAY NIGHT...AGAIN LIGHT WIND FIELD AND INCREASING CLOUD
COVER WILL CREATE FOR A TRICKY HIGH TEMPERATURE FORECAST. MODELS
INDICATE A COOLER AIR MASS THAN ON SATURDAY. TRENDED COOLER OR
TOWARD COOLER GUIDANCE.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 342 AM MST FRI DEC 14 2012
AN UPPER LEVEL RIDGE WILL MOVE OVER THE AREA THE FIRST PART OF NEXT
WEEK. FOLLOWING THE RIDGE WILL BE A SHORT WAVE TROUGH...WHICH WILL
APPROACH THE AREA WEDNESDAY. AHEAD OF THE TROUGH THERE MAY BE A
CHANCE FOR SOME PRECIPITATION WEDNESDAY AS A COLD FRONT MOVES
THROUGH. AT THIS TIME MODELS DISAGREE WITH THE TIMING OF THE FRONT
BY AS MUCH AS 12 HOURS. IN ADDITION...LIFT ALONG THE FRONT DOES NOT
LOOK STRONG ENOUGH AT THIS POINT TO DEVELOP ANY PRECIPITATION AND
THE ENVIRONMENT MOISTENS BEHIND THE FRONT WHERE THERE IS ALMOST NO
LIFT. IF MODELS COME INTO A BETTER AGREEMENT WITH THE FRONTAL
PASSAGE...AND IF THE LIFT ALONG THE FRONT WILL STRENGTHEN WITH A
BETTER SUPPLY OF MOISTURE...A MENTION OF PRECIPITATION WILL THEN BE
WARRANTED.
TEMPERATURES FOR THE PERIOD WILL WARM THROUGH WEDNESDAY AHEAD OF THE
COLD FRONT...WITH VALUES 10 TO 15 DEGREES ABOVE NORMAL. AFTER THE
COLD FRONT TEMPERATURES RETURN TO NEAR NORMAL VALUES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1036 AM MST FRI DEC 14 2012
TAFS SEEM TO BE ON TRACK FOR LOWER CIGS AND CHANCE OF LIGHT
PRECIPITATION DEVELOPING AT BOTH TERMINALS THIS AFTERNOON AND
OVERNIGHT. UPPER LEVEL TROUGH IS CURRENTLY MOVING ACROSS THE FOUR
CORNERS REGION AND LIGHT PRECIPITATION IS DEVELOPING AND REACHING
THE SURFACE ACROSS PORTIONS OF EASTERN COLORADO. EXPECT
SCATTERED PRECIPITATION TO DEVELOP AT KGLD AROUND 20-21Z WITH
DEVELOPMENT AT KMCK A BIT LATER AROUND 22-23Z. ATTM KMCK LOOKS TO
BE THE BETTER RECIPIENT FOR MEASURABLE PRECIP WHICH MAY BRING
VSBY DOWN TO MVFR FOR A FEW HOURS TONIGHT. CIGS STILL REMAIN A
TRICKY FORECAST WITH MODELS BRINGING KMCK DOWN TO IFR AND MAYBE A
BRIEF PERIOD OF LIFR OVERNIGHT. UPPER LEVEL SYSTEM WILL BE EAST OF
THE AREA BY 06-08Z WITH SKIES GRADUALLY CLEARING THROUGH THE END
OF THE PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
UPDATE...PMM
SHORT TERM...BULLER
LONG TERM...JTL
AVIATION...PMM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1054 AM MST FRI DEC 14 2012
.SHORT TERM...(TODAY THROUGH SUNDAY NIGHT)
ISSUED AT 342 AM MST FRI DEC 14 2012
MAIN FORECAST CONCERN WILL BE STORM SYSTEM THAT WILL IMPACT THE AREA
THROUGH TONIGHT. SATELLITE SHOWING A PROGRESSIVE NEARLY ZONAL FLOW
FROM THE PACIFIC INTO THE WESTERN ATLANTIC. THE EXCEPTION TO THIS
IS THE SYSTEM THAT IS CUT OFF FROM THE FLOW AND EXTENDS FROM NEVADA
TO JUST OFF THE SOUTHERN CALIFORNIA COAST. THROUGH 05Z THIS SYSTEM
WAS STILL DIGGING AND NOT MAKING ANY PROGRESS EAST YET. THIS TROUGH
HAS PULLED UP SUBTROPICAL MOISTURE AHEAD OF IT.
AT JET LEVEL...THE NAM...UKMET AND SREF LOOK TO HAVE THE JET SEGMENT
COMING IN FROM THE SOUTHWEST THE BEST. OTHER MODELS TENDED TO HAVE
THE HIGHER SPEEDS TOO FAR NORTH OR EAST. AT MID LEVELS...WITH THE
INCOMING UPPER TROUGH...MODELS TENDED TO BE TOO FAR SOUTH AND EAST.
THE GFS AND CANADIAN WERE DOING A LITTLE BETTER THAN THE SREF AND
NAM. MODELS ALSO TENDED TO BE TOO GENEROUS WITH THE MID LEVEL
MOISTURE. MODELS ARE HAVING A HARD CATCHING THE SUBTLE COLD FRONT
THAT SAGGED OVER THE AREA TODAY. THE NAM AND RUC WERE DOING THE
BEST. ALSO MODELS ARE TOO GENEROUS WITH LOW LEVEL MOISTURE WITH THE
HIGHER DEWPOINTS TOO FAR NORTH ALREADY. THE GFS AND CANADIAN WERE
DOING THE BEST ON THE LOW LEVEL THERMAL FIELD.
TODAY/TONIGHT...LEFT FRONT QUADRANT OF THE JET CONTINUES TO MOVE
CLOSE TO AREA AND AFFECTS THE AREA MAINLY FROM 12Z TO 18Z. DURING
THAT TIME IT LOOKS LIKE THERE IS NOT A LOT OF LOW LEVEL MOISTURE BUT
LITTLE MOISTURE IN THE COLUMN. SURFACE OBSERVATIONS AND 00Z SOUNDINGS
TO OUR SOUTH ARE VERY DRY. BY THE TIME THE MOISTURE GETS HERE...THE
MAIN JET IS WELL EAST. SPEAKING OF MOISTURE RETURN...DEWPOINTS
REMAIN VERY LOW AND THERE IS NO SIGNIFICANT INCREASE IN MOISTURE
UNTIL WELL SOUTH. MODELS ARE OVERDOING MOISTURE RETURN RIGHT NOW.
00Z SOUNDINGS OVER OUR AREA AND TO THE SOUTH ARE EXTREMELY DRY.
MOISTURE TRAJECTORIES WOULD SUPPORT BEST MOISTURE FURTHER SOUTH AND
EAST. ALSO THUNDERSTORMS WILL BE DEVELOPING TO OUR SOUTH AND EAST
AND SLOW DOWN OR ROB ANY MOISTURE RETURN WE WERE GOING TO SEE.
DUE TO THE SUBTROPICAL MOISTURE RETURN...THERE LOOKS TO BE A
SIGNIFICANT MID/UPPER LEVEL CLOUD DECK WHICH WILL INHIBIT HEATING
AND ANY SURFACE INSTABILITY. MODELS ARE ALSO SHOWING LITTLE TO NO
ELEVATED CAPE AS WELL. WITH MODELS OVERDOING THE INFLUX OF MOISTURE
MODELS ARE PROBABLY OVERDOING ANY INSTABILITY AS WELL. SO CHOSE TO
KEEP THUNDER OUT OF THE FORECAST.
00Z MODEL DATA WAS HINTING AT IT AND NOW 06Z IS CATCHING ONTO IT
EVEN MORE. THE MODELS STILL BRING THE SYSTEM ACROSS IN A NEGATIVE
TILT. HOWEVER...THEY BRING IT ACROSS WITH A NORTHERN AND SOUTHERN
CIRCULATION ON EITHER SIDE OF THE FORECAST AREA. MODELS HAVE BACKED
THEIR IDEA OF ANY WRAP AROUND ON THE BACKSIDE OF THE SYSTEM. PLUS
MODELS HAVE PUSHED EASTERN BAND OF PRECIPITATION FURTHER SOUTH AND
EAST. SO IN A NUTSHELL BEST MOISTURE...LIFT...AND INSTABILITY ARE
NOT INSYNC OR NOT THERE. AT THIS TIME IT STILL DOES LOOK LIKE THE
NORTHEAST PORTION OF THE AREA WILL HAVE THE BEST CHANCE FOR
MEASURABLE PRECIPITATION WITH LITTLE TO NONE FURTHER SOUTHWEST AND
WEST YOU GO.
NEW MODEL GUIDANCE SLOWED THINGS DOWN ON PRECIPITATION ARRIVAL AND
LIMITED POPS TO THE AFTERNOON AND TIERED THEM FROM LOWEST TO HIGHEST
PER REASONING ABOVE. BELIEVE PRECIPITATION WILL SHUT OFF PRETTY QUICK
GIVEN THE SPEED OF THE SYSTEM AND MODEL DEFICIENCIES MENTIONED
ABOVE. BELIEVE MOST OF THE PRECIPITATION WILL BE DOWN BY OR SHORTLY
AFTER 06Z. DID HOLD ONTO PRECIPITATION AFTER THAT JUST KEEP WITHIN
SOME CLOSENESS WITH MY NEIGHBORS. IN REGARDS TO PHASE. LOOKS LIKE IT
STAYS RAIN THROUGH THE DAY. MODEL SOUNDINGS INDICATE TEMPERATURES
STAYING ABOVE FREEZING FOR MOST OF THE NIGHT EVEN IF THERE IS ICE IN
THE COLUMN. SOUNDINGS ARE ALSO NOT OPTIMISTIC ABOUT ICE IN THE
COLUMN EITHER. IT ALSO LOOKS BY THE TIME THE AIR MASS GETS COLD
ENOUGH TO SUPPORT SNOW...THE LIFT AND MOISTURE ARE GONE. SO ONLY
HAVE A MIX OF RAIN AND SNOW AT BEST. THEREFORE THERE SHOULD BE
LITTLE TO NO SNOW ACCUMULATION.
PRIOR TO ARRIVAL OF CLOUDS TEMPERATURES HAVE COOLED OFF
DRAMATICALLY THIS MORNING WITH MODELS TOO WARM. COMBINATION OF
UNFAVORABLE WIND FIELD AND INCREASING CLOUD COVER/DEVELOPING
PRECIPITATION WILL KEEP TEMPERATURES FROM WARMING MUCH. BELIEVE THE
GEM WAS CATCHING THE IDEA THE BEST AND I MAY BE TOO WARM.
SATURDAY/SATURDAY NIGHT...TRICKY MAX TEMPERATURE FORECAST. NORTHWEST
WINDS AND SOME SUN EARLY WILL ALLOW FOR TEMPERATURES TO WARM. BUT
NEXT SHORTWAVE TROUGH WILL DRAMATICALLY INCREASE CLOUD COVER IN THE
AFTERNOON. CHOSE TO TOWARD THE COOLER SIDE. FOR THE NIGHT MODELS
STILL PRODUCING QPF. MODELS DIFFER ON WHERE TO PUT IT BUT GENERALLY
FAVOR THE SOUTHWEST. NOT UNREASONABLE FOR PRECIPITATION TO OCCUR
ANYWHERE BUT AM NOT TOTALLY SOLD ON ANYTHING OCCURRING. SO
BROADBRUSHED LOW SLIGHT CHANCE POPS FOR THE ENTIRE AREA.
SUNDAY/SUNDAY NIGHT...AGAIN LIGHT WIND FIELD AND INCREASING CLOUD
COVER WILL CREATE FOR A TRICKY HIGH TEMPERATURE FORECAST. MODELS
INDICATE A COOLER AIR MASS THAN ON SATURDAY. TRENDED COOLER OR
TOWARD COOLER GUIDANCE.
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 342 AM MST FRI DEC 14 2012
AN UPPER LEVEL RIDGE WILL MOVE OVER THE AREA THE FIRST PART OF NEXT
WEEK. FOLLOWING THE RIDGE WILL BE A SHORT WAVE TROUGH...WHICH WILL
APPROACH THE AREA WEDNESDAY. AHEAD OF THE TROUGH THERE MAY BE A
CHANCE FOR SOME PRECIPITATION WEDNESDAY AS A COLD FRONT MOVES
THROUGH. AT THIS TIME MODELS DISAGREE WITH THE TIMING OF THE FRONT
BY AS MUCH AS 12 HOURS. IN ADDITION...LIFT ALONG THE FRONT DOES NOT
LOOK STRONG ENOUGH AT THIS POINT TO DEVELOP ANY PRECIPITATION AND
THE ENVIRONMENT MOISTENS BEHIND THE FRONT WHERE THERE IS ALMOST NO
LIFT. IF MODELS COME INTO A BETTER AGREEMENT WITH THE FRONTAL
PASSAGE...AND IF THE LIFT ALONG THE FRONT WILL STRENGTHEN WITH A
BETTER SUPPLY OF MOISTURE...A MENTION OF PRECIPITATION WILL THEN BE
WARRANTED.
TEMPERATURES FOR THE PERIOD WILL WARM THROUGH WEDNESDAY AHEAD OF THE
COLD FRONT...WITH VALUES 10 TO 15 DEGREES ABOVE NORMAL. AFTER THE
COLD FRONT TEMPERATURES RETURN TO NEAR NORMAL VALUES.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1036 AM MST FRI DEC 14 2012
TAFS SEEM TO BE ON TRACK FOR LOWER CIGS AND CHANCE OF LIGHT
PRECIPITATION DEVELOPING AT BOTH TERMINALS THIS AFTERNOON AND
OVERNIGHT. UPPER LEVEL TROUGH IS CURRENTLY MOVING ACROSS THE FOUR
CORNERS REGION AND LIGHT PRECIPITATION IS DEVELOPING AND REACHING
THE SURFACE ACROSS PORTIONS OF EASTERN COLORADO. EXPECT
SCATTERED PRECIPITATION TO DEVELOP AT KGLD AROUND 20-21Z WITH
DEVELOPMENT AT KMCK A BIT LATER AROUND 22-23Z. ATTM KMCK LOOKS TO
BE THE BETTER RECIPIENT FOR MEASURABLE PRECIP WHICH MAY BRING
VSBY DOWN TO MVFR FOR A FEW HOURS TONIGHT. CIGS STILL REMAIN A
TRICKY FORECAST WITH MODELS BRINGING KMCK DOWN TO IFR AND MAYBE A
BRIEF PERIOD OF LIFR OVERNIGHT. UPPER LEVEL SYSTEM WILL BE EAST OF
THE AREA BY 06-08Z WITH SKIES GRADUALLY CLEARING THROUGH THE END
OF THE PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...BULLER
LONG TERM...JTL
AVIATION...PMM
AREA FORECAST DISCUSSION
NWS CARIBOU ME
1235 PM EST FRI DEC 14 2012
.SYNOPSIS...
WEAK LOW PRESSURE WILL PASS NORTH OF THE AREA THIS MORNING WITH A
COLD FRONTAL PASSAGE LATER TODAY AND TONIGHT. HIGH PRESSURE BUILDS
NORTH OF THE REGION SATURDAY.&&
.NEAR TERM /THROUGH TONIGHT/...
1235 PM UPDATE...SNOW SHOWERS HAVE DEVELOPED AT KFVE AND THE VSBY
RAPIDLY DROPPED TO 3/4 OF A MILE. SNOW SHOWERS WILL MOVE OFF TO
THE SOUTHEAST THIS AFTERNOON WITH LOCAL ACCUMULATIONS OF UP TO AN
INCH. A SPECIAL WEATHER STATEMENT WAS ISSUED EARLIER FOR THE SNOW
SHOWERS. UPDATED THE POP/QPF/SNOWFALL GRIDS FOR THE REMAINDER OF
THE AFTERNOON TO BETTER LINE UP WITH LATEST RADAR TRENDS.
907 AM UPDATE...THE MAIN UPDATE WAS TO LOWER THE CLOUD COVER A
BIT DOWN TOWARD THE COAST AS SAT PICTS...OBS...AND WEB CAMS
INDICATE P/SUNNY TO M/SUNNY CONDITIONS. ALSO MADE SOME TWEAKS TO
THE WIND GUST GRIDS ACROSS THE COASTAL WATERS TO HOLD OFF WIND
GUSTS TO 25 KT UNTIL THE START TIME OF THE SCA AT 21Z.
OTHERWISE...THE FORECAST LOOKS TO BE IN GOOD SHAPE. STILL EXPECT
SNOW SHOWERS TO DEVELOP ACROSS THE NORTH THIS PM AS A STRONG
ARCTIC COLD FRONT BEGINS TO WORK ACROSS THE AREA.
UPDATE 0625 EST: HAVE ADJUSTED TEMPERATURE...WEATHER AND POPS.
LOW PRESSURE IS CURRENTLY PASSING TO THE NORTH OF THE STATE. A
STRONG COLD FRONT TRAILING THE LOW WILL APPROACH FROM THE WEST
THIS MORNING THE MOVE ACROSS THE STATE DURING THE AFTERNOON.
STRONG COLD ADVECTION BEHIND THE FRONT ALONG WITH AN UPPER TROUGH
WILL RESULT IN UNSTABLE CONDITIONS RESULTING IN SNOW SQUALLS
ESPECIALLY IN THE NORTH DURING THE AFTERNOON INTO THE EVENING.
WILL USE THE RUC13 TO INITIALIZE THE POP GRIDS THROUGH THE MORNING
THEN TRANSITION TO A BLEND OF THE NAM12 ...GFS40 ...SREF AND
ECMWF. FOR QPF WILL ALSO USE SAME MODEL BLEND AND EXCHANGE THE
NAM12 FOR NAM80. FOR SNOW AMOUNTS WILL RUN SNOW FROM THICKNESS
TOOL ON NAM/QPF GRIDS. THE GMOS WAS USED TO INITIALIZE THE
TEMPERATURE AND DEW POINT GRIDS. HAVE MANUALLY ADJUSTED MAXIMUM
AND MINIMUM TEMPERATURES. USED A NAM12/GMOS BLEND FOR WIND SPEED.
FOR WIND GUSTS WILL USE 200 PERCENT OF SUSTAINED SPEED WITH GOOD
MIXING EXPECTED.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
COLDER WEATHER IN STORE FOR THE WEEKEND.
ARCTIC AIR WILL CONTINUE TO PUSH INTO THE CWA ON SATURDAY W/NNW
WINDS ADDING A CHILL TO THE AIR. THIS WILL MEAN SATURDAY`S HIGHS
WILL BE BELOW NORMAL FOR THE IDES OF DECEMBER. A COLD NNW FLOW OFF
THE OPEN ST. LAWRENCE WILL LEAD TO CLOUDS ACROSS NORTHERN 1/2 OF
THE CWA W/SOME FLURRIES OR BANDS OF LIGHT SNOW THROUGH SATURDAY
AFTERNOON. THE NAM AND GFS TEND TO STRUGGLE W/THSI TYPE OF SETUP.
THE CANADIAN GEM LOOKS LIKE IT PICKS UP ON THIS WELL AND DECIDED
TO USE IT TO SET UP THE FORECAST FOR SATURDAY INTO SATURDAY NIGHT.
SKIES WILL GRADUALLY CLEAR ACROSS THE NORTHERN AREAS SATURDAY
NIGHT AS THE FLOW WEAKENS WHILE THE CENTRAL AND DOWNEAST REGION
REMAIN CLEAR. ALL THIS ALLOWING FOR SOME COLD TEMPERATURES BY
EARLY SUNDAY MORNING. STAYED CLOSE TO THE DAYCREW`S ASSESSMENT OF
READINGS AOB 0F ACROSS THE NORTH AND WEST AND IN THE SINGLE
NUMBERS FOR THE CENTRAL AND DOWNEAST REGIONS.
HIGH PRES WILL MOVE ACROSS NORTHERN QUEBEC AND RIDGE DOWN ACROSS
THE REGION ON SUNDAY. AT THE SAME TIME, LOW PRES MOVING ACROSS THE
GREAT LAKES REGION IS FCST TO RE-DEVELOP OFF THE NJ COAST BY
SUNDAY NIGHT. ATTM, DECIDED TO KEEP THE CWA DRY BANKING ON THE
STRONG HIGH TO THE NORTH HOLDING ON LONGER. THIS MATCHES UP WELL
THE LATEST RUNS OF THE NAM/GFS AND ECMWF. WE WILL SEE INCREASING
CLOUDS FROM THE SW DURING THE DAY W/A GRADUAL MODERATION IN
TEMPERATURES BUT STILL BELOW NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
THINGS BEGIN TO GET COMPLICATED ESPECIALLY WEDNESDAY INTO
THURSDAY. DETAILS ARE BELOW.
THE 00Z RUNS OF THE ECMWF/OPERATIONAL GFS AND ITS MEAN ENSEMBLE
SUPPORT LOW PRES REDEVELOPING NEAR NJ SUNDAY NIGHT AND THEN SLOWLY
MOVING ENE OFF THE LONG ISLAND COAST. THE GFS IS MOST PROMINENT
W/THIS FEATURE WHILE THE ECWMF AND THE CANADIAN GLOBAL KEEP THE
SYSTEM LESS AMPLIFIED AND SHOW THE HIGH PRES RIDGE HOLDING ON
LONGER KEEPING THE BULK OF THE PRECIP FURTHER S. DECIDED TO BLEND
THE ECMWF AND GFS FOR THIS SYSTEM SUNDAY NIGHT INTO MONDAY. THIS MEANS
CHC POPS SUNDAY NIGHT FOR THE INTERIOR DOWNEAST AND COAST WHICH
MATCHES UP WELL W/GYX AND STAYED DRY FURTHER NORTH GIVEN THE
RIDGE HOLDING IN LONGER.
THE CHALLENGE NOW COMES FOR MONDAY RIGHT INTO LATE WEEK. THE
ECMWF DOES SHOW A MORE SIGNIFICANT LOW MOVING ACROSS THE DELMARVA
ON MONDAY AND LIFTING THROUGH THE GULF OF MAINE LATER TUESDAY INTO
WEDNESDAY AND THEN WEAKENS THIS LOW W/YET ANOTHER LOW FURTHER TO
THE E TAKING OVER BY THURSDAY AND ENDING THE PRECIP SOONER. THIS
WOULD MEAN SIGNIFICANT A SNOWFALL FOR THE CWA TUESDAY INTO WEDNESDAY
W/DRIER CONDITIONS ON THURSDAY. THE OPERATIONAL GFS HAS THIS LOW
DEVELOPING OFF THE MID ATLC COAST AND LIFTING NORTHWARD AND
INTENSIFYING W/POSSIBLE BLIZZARD CONDITIONS WEDNESDAY INTO
THURSDAY. TO ADD TO THE CONFUSION, 7 OUT OF THE 12 GFS ENSEMBLE
MEMBERS KEEP THIS LOW FURTHER S AND E BY THE SAME TIMEFRAME.
DECIDED TO GO W/LIKELY POPS(60-70%) FOR THE INTERIOR DOWNEAST AND
THE COAST FOR MONDAY INTO TUESDAY AND CHC POPS FURTHER NORTH.
TEMPERATURES LOOK COLD ENOUGH FOR SNOW ALL THE WAY TO THE COAST.
CONFIDENCE DROPS OFF WEDNESDAY INTO THURSDAY GIVEN THE
DISCREPANCIES IN THE LONG RANGE GUIDANCE. CONCERN IS THERE THAT
THE BLOCKING PATTERN SETTING UP OVER NORTHERN CANADA COULD LEAD TO
LOW PRES SYSTEMS BEING SHUNTED FURTHER S AND E. THEREFORE, KEPT
CHC POPS FOR THIS TIMEFRAME. THE DAYCREW CAN ASSESS THIS FURTHER
W/LATER MODEL RUNS. ADJUSTED THE GMOS MAXES DOWN WEDNESDAY INTO
THURSDAY BLENDING IN THE ECMWF TEMPERATURES. ALSO CUT BACK ON
WINDS SPEEDS FROM 40-50 MPH GUSTS DOWN TO 35 MPH. WOULD LIKE TO
SEE A BETTER CONSENSUS OF THE GUIDANCE BEFORE SHOOTING THAT HIGH.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
NEAR TERM: BRIEF PERIOD OF MVFR/IFR CONDITIONS POSSIBLE DUE TO
SNOW SHOWERS AND CEILINGS THIS AFTERNOON INTO THIS EVENING...
OTHERWISE VFR CONDITIONS.
SHORT TERM: COULD BE SEEING SOME MVFR CONDITIONS FOR THE NORTHERN
TERMINALS SATURDAY AND THEN CONDITIONS LOOK LIKE THEY WILL GO VFR
THROUGH SUNDAY. THE CHALLENGE COMES MONDAY INTO TUESDAY W/A POSSIBLE
STORM SYSTEM BRINGING SNOW AND POSSIBLE ICING W/MVFR TO IFR.
&&
.MARINE...
NEAR TERM: HAVE USED A BLEND OF THE NAM12 AND GFS40 TO INITIALIZE
THE WINDS. HAVE INCREASED THE WIND SPEED SEVERAL KNOTS LATER
TONIGHT AS COLDER AIR MOVES ACROSS THE WATERS. FOR WAVES: EXPECT
SOUTHWEST FETCH TO DEVELOP ACROSS THE GULF OF MAINE THIS AFTERNOON
IN TIGHT GRADIENT AHEAD OF APPROACHING FRONT. PRIMARY WAVE GROUP
BUILDING TO 5-6 FEET/6 SECONDS. SECONDARY LONG PERIOD WAVE GROUP
FROM SOUTHEAST. WILL MOVE STARTING TIME FOR SCA TO 2100Z.
SHORT TERM: SCA CONDITIONS MAY NEED TO BE EXTENDED THROUGH
SATURDAY AFTERNOON AS NW WINDS COULD GUST TO 25 KTS W/CAA OVER THE
WATERS ESPECIALLY THE OUTER ZONES. USE A NAM12/GFS BLEND FOR THE
SUSTAINED WINDS SHOWING 15-20 KTS W/GUSTS HITTING 25 KTS ON
SATURDAY. WINDS DROP OFF SATURDAY NIGHT RIGHT THROUGH SUNDAY TO
10-15 KTS. SEAS WILL REMAIN 3-5 FT AT BEST FOR THIS TIME PERIOD.
WINDS/SEAS COULD INCREASE SIGNIFICANTLY MONDAY NIGHT INTO TUESDAY
AS A LOW PRES SYSTEM APCHS FORM THE S. ENE WINDS COULD HIT SCA OR
EVEN GALES. DECIDED TO BACK AWAY FROM THE GMOS ATTM AND CUT BACK
THOSE SPEEDS BY 10 KTS. THIS MEANS SUSTAINED WINDS OF 20-25 KTS
AND GUSTS UP TO 35 KTS. INCREASED THE SEAS UP TO 8-10 FT BY TUESDAY.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 4 PM EST
SATURDAY FOR ANZ050>052.
&&
$$
NEAR TERM...CB/MIGNONE
SHORT TERM...HEWITT
LONG TERM...HEWITT
AVIATION...CB/MIGNONE
MARINE...CB/MIGNONE/HEWITT
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
345 PM CST FRI DEC 14 2012
.DISCUSSION...
A POWERHOUSE UPPER LEVEL LOW AND ATTENDANT PACIFIC COLD FRONT ARE
SWEEPING INTO WEST TEXAS THIS AFTERNOON. THE PV15 SFC SUGGESTS
THIS FRONT WILL MOVE RAPID NORTHEAST INTO KS OVERNIGHT. THE LINE
OF STORMS AND CONVECTION SHOULD FOLLOW THE PV15 SFC. NORTH OF THIS
FEATURE AN AREA OF RAIN AND ISOLATED TSTMS ACROSS WRN KS WILL PUSH
INTO WRN AND NCNTL NEB OVERNIGHT. THE RAP13 SUGGESTS A WEAK AREA
OF DEFORMATION SUPPORTING RAIN TONIGHT. QPF AMOUNTS BETWEEN 1/10
AND 1/3 OF AN INCH ARE EXPECTED...MAINLY EAST OF HIGHWAY 83.
THE PTYPE IS VERY PROBLEMATIC AS EVAPORATIVE COOLING WILL COMPETE
WITH WARM AIR ADVECTION. THE RAP SUGGESTS SUB FREEZING TEMPS ALONG
THE WRN AND NRN EDGES OF THE PCPN SHIELD BY MORNING WITH ICONS OF
SNOW AND FREEZING RAIN. H7 TEMPS ARE 0 TO -5C...NOT VERY COLD AND
VERY SLOW FOR SNOW GROWTH. SO WE WILL MONITOR CONDITIONS AND
PERHAPS WINTER WEATHER CONDITIONS WILL DEVELOP TOWARD MORNING.
THE CONVECTION ACROSS KS TONIGHT WILL LIKELY CAUSE THE H7 LOW TO
JOG SOUTHEAST AWAY FROM THE FCST AREA AS INDICATED BY MOST OF THE MODELS.
THIS COULD EASILY CUT OFF THE FORCING FOR RAIN.
THE MODELS SHOW A WEAK CANADIAN HIGH BUILDING DOWN SATURDAY
FOLLOWED BY AN UPPER LEVEL DISTURBANCE DROPPING THRU SWRN NEB LATE
SATURDAY NIGHT WHICH WOULD SUPPORT FLURRIES OR PERHAPS ISOLATED
SNOW SHOWERS. THEREAFTER...MONDAY AND TUESDAY...LOW PRESSURE WILL
FORM ACROSS THE NRN HIGH PLAINS FOLLOWED BY AN ARCTIC FRONT
WEDNESDAY. ALL MODELS SUGGEST SUFFICIENT MOISTURE AND LOW LEVEL
SATURATION FOR A CHANCE OF SNOW OR SNOW SHOWERS. THIS IS TO BE
FOLLOWED BY A SECOND ARCTIC PUSH FRIDAY. BOTH OF THESE HIGH
PRESSURE SYSTEMS WILL MOVE QUICKLY OFF TO THE EAST AS A FAST UPPER
LEVEL FLOW CONTINUES.
&&
.AVIATION...
FOR THE 18Z TAF FORECAST CYCLE. UPPER LEVEL WAVE WILL RAPIDLY
ADVANCE FROM THE DESERT SOUTHWEST INTO THE CENTRAL PLAINS
TODAY/TONIGHT AND DEEPEN A SURFACE LOW OVER THE HIGH PLAINS OF
EASTERN COLORADO. PRECIPITATION IS SHOWN TO SPREAD NORTHEAST FROM
EASTERN COLORADO INTO THE PLAINS LATE THIS AFTERNOON...WITH THE
POTENTIAL OF MIXED PRECIPITATION AT BOTH KLBF AND KVTN AFTER 06Z
TONIGHT. THERE IS STILL SOME CONSIDERABLE SPREAD REGARDING THE TRACK
OF THE SURFACE LOW...AND THE POTENTIAL OF CONVECTION ACROSS THE
SOUTHERN HIGH PLAINS MAY ALLOW FOR A FURTHER SOUTHERN TRACK OF THE
SYSTEM. THUS CONFIDENCE IN THE TAF FORECAST IS LOW...BUT WILL
RETAIN -RASN WITH MVFR /POSSIBLY LOWER/ AT BOTH AREA TERMINAL FOR
THE TIME BEING...ESPECIALLY GIVEN RECENT RADAR TRENDS JUST SOUTH OF
KLBF. SHORT FUSED UPDATES MAY BE NEEDED. ONE LAST NOTE...DOWNWARD
TRANSFER OF MOMENTUM MAY OCCUR UNDER ANY SHOWER/LINE OF SHOWERS. A
BRIEF PERIOD OF WIND GUSTS AT OR ABOVE 20KTS WOULD BE POSSIBLE.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...TALYOR/CDC
AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1007 AM CST FRI DEC 14 2012
.DISCUSSION...
MAIN ADJUSTMENTS FOR THIS MORNING WERE TO INCREASE CLOUD COVER IN
THE SOUTHEAST AND ADD IN A FOG MENTION IN THE WEST FOR THE REST
OF THE MORNING. SAT LOOP SHOWS A FAIR AMOUNT OF MID AND HIGH
CLOUDS MOVING INTO THE SOUTHEASTERN CWA THIS MORNING...AND MODELS
HAVE LOW LEVEL RH VALUES INCREASING THROUGHOUT THE DAY. HRRR SHOWS
A FAIR AMOUNT OF CLOUDS MOVING INTO THE EASTERN CWA...ALTHOUGH THE
HOLE IN THE NORTHEAST SHOULD KEEP THAT AREA CLEAR FOR A BIT LONGER
THIS MORNING INTO EARLY AFTERNOON. FURTHER WEST...LOTS OF STRATUS
CONTINUES SO WILL CONTINUE TO KEEP A CLOUDY MENTION THERE. THERE
IS ALSO SOME FOG ALONG THE SLIGHTLY HIGHER TERRAIN AT VALLEY
CITY...COOOPERSTOWN...AND LANGDON. WEB CAMS IN THE WESTERN
COUNTIES SHOW QUITE A BIT OF FOG...ALTHOUGH WIDESPREAD
VISIBILITIES ARE STILL MOSTLY ABOVE 1/4 MILE WITH COOPERSTOWN THE
ONLY ONE SHOWING DENSE. WILL INCLUDE A MENTION OF FOG IN THE
GRIDS...BUT WILL HOLD OFF ON ANY DENSE FOG ADVISORIES UNLESS MORE
STATIONS TAKE A TURN FOR THE WORSE. KEPT HIGHS IN THE 20S ACROSS
MOST OF THE CWA...WITH SOME LOCATIONS APPROACHING 30 IN THE
SOUTHEAST WHERE READINGS ARE ALREADY IN THE 20S THIS MORNING.
&&
.AVIATION...
STRATUS AND A BIT OF FOG WITH IFR TO MVFR CONDITIONS COVER THE
WESTERN THREE TAF SITES...WHILE THE EAST REMAINS VFR FOR THE TIME
BEING. STATIONS ON THE EDGE OF THE STRATUS DECK...KGFK AND KFAR
MAY SEE SOME BRIEF IMPROVEMENT THIS AFTERNOON WHILE KTVF GOES DOWN
AT TIMES. ALL STATIONS WILL GO DOWN TO MVFR OR LOWER AFTER 06Z
TONIGHT.
&&
.PREV DISCUSSION... /ISSUED 350 AM CST FRI DEC 14 2012/
SHORT TERM (TODAY-SUNDAY NIGHT)...CLOUD TRENDS AND PRECIP
CHANCES/TYPE WILL BE THE CHALLENGE. 00Z MODELS INITIALIZED WITH
MINIMAL ERRORS...BUT CONTINUE TO SHOW DIFFERENCES THROUGH THE
PERIOD. THE ECMWF HAS BEEN MOST CONSISTENT RUN TO RUN AND WILL
FOLLOW FOR DETAILS.
UPPER TROUGH IS CRASHING THE SOUTHWEST CONUS AND WILL EJECT INTO
THE CENTRAL PLAINS TONIGHT.
FOR TODAY...SOUTHERLY LOW LEVEL FLOW WILL CONTINUE ALONG WITH WARM
AIR ADVECTION. 06Z RAP INDICATES 925MB WAA STRONGEST ACROSS THE
EASTERN FA...WITH 925MB DEWPOINTS NOT INCREASING MUCH. THIS WOULD
KEEP SKY MOSTLY CLOUDY WEST AND MOSTLY CLEAR EAST. IF THIS SKY
PREDICTION COMES TRUE...TEMPS WOULD LIKELY ONLY RISE A FEW
DEGREES ACROSS THE WEST...AND WOULD APPROACH THE FREEZING MARK
ACROSS THE EAST.
TONIGHT-SATURDAY...MODELS STILL HAVE DIFFERENCES WITH THE SPEED
AND TRACK OF THE MID-LEVEL TROUGH LEADING TO FAIRLY LOW
CONFIDENCE. THIS SYSTEM IS NOT THE STRONGEST...BUT THE GULF
APPEARS OPEN AND PWATS SHOULD BE OVER 0.5 INCH. THE MAIN FORCING
MECHANISM TO AFFECT THIS FA WILL BE DEFORMATION AS A 700MB LOW
TRACKS INTO NORTHERN MINNESOTA. A FEW QUESTIONS STILL
UNCERTAIN...1) HOW QUICKLY WILL HIGHER 925MB MOISTURE SURGE
NORTHWARD...2) P-TYPE AND FZRA POTENTIAL...3) HOW MUCH SNOW. THE
GFS IS THE QUICKEST BRINGING ABOVE 0C DEWPOINTS INTO THE EASTERN
FA TONIGHT. THIS WOULD LEAD TO A PROLONGED DZ/FZDZ SCENARIO BEFORE
DEFORMATION ZONE ARRIVES. ALL OTHER MODELS ARE NOT AS QUICK WITH
THIS MOISTURE SURGE...AND THE PROBABILITY FOR A PROLONGED PERIOD
OF FZDZ APPEARS LOW AT THIS POINT. AS THE MAIN PRECIP SHIED
ARRIVES INTO THE FA...THE 925-850MB LAYER WILL BE ABOVE FREEZING.
HOWEVER...EVAPORATIVE COOLING SHOULD QUICKLY CHANGE LIQUID PRECIP
TO SNOW...AND LIMIT FZRA. DID INSERT A SLIGHT CHANCE FOR FZRA INTO
THE WX GRIDS FOR 09Z-15Z SATURDAY. MODEL QPF SUGGESTS 1-3 INCHES
OF SNOW POSSIBLE ACROSS THE EASTERN FA. THE ABOVE SCENARIO IS WITH
FOLLOWING THE ECMWF...WHICH IS ONE SOLUTION OF MANY...HOPEFULLY
ANOTHER MODEL RUN CAN INCREASE CONFIDENCE WITH THE ABOVE
QUESTIONS.
MODELS APPEAR TO WANT TO KEEP MID-LEVEL CIRCULATION NEAR THE FA ON
SUNDAY...WHICH WOULD LEAD TO MORE CLOUDS AND POSSIBLE FLURRIES.
WILL NEED TO MONITOR THIS TREND IN THE MODELS.
LONG TERM (MONDAY-THURSDAY)...
OVERALL...THERE IS PRETTY GOOD AGREEMENT AMONG THE MODELS WITH
OVERALL SYNOPTIC EVOLUTION OF THE PATTERN DURING THIS PERIOD...WITH
MORE UNCERTAINTY REGARDING THE FORECAST DETAILS. THE PERIOD WILL
BEGIN WITH WEAK SFC HIGH PRESSURE UNDER FAIRLY ZONAL FLOW ALOFT.
TEMPERATURES ON MONDAY AND TUESDAY ARE EXPECTED TO BE WITHIN A FEW
DEGREES OF SEASONAL NORMS. HAVE KEPT THESE DAYS MAINLY
DRY...ALTHOUGH WITH GUIDANCE SHOWING WEAK UPPER WAVES CASCADING
THROUGH THE FLOW...A BIT OF LIGHT SNOW COULD NOT BE RULED OUT.
IT APPEARS THAT A RELATIVELY PROGRESSIVE LONGWAVE TROUGH WILL SHIFT
FROM THE ROCKIES INTO THE PLAINS DURING THE MIDDLE OF NEXT WEEK.
THIS WOULD SUPPORT THE DEVELOPMENT OF A LEE CYCLONE ACROSS COLORADO
LIFTING INTO THE PLAINS. THE 00Z GFS IS MORE PROGRESSIVE AND LESS
AMPLIFIED THAN THE 00Z ECMWF/GEM WITH THIS FEATURE. A MORE AMPLIFIED
SOLUTION SUCH AS THE ECMWF/GEM WOULD SUPPORT STRONGER SFC
CYCLOGENESIS SOMEWHERE ACROSS THE PLAINS. HOWEVER...MODEL SPREAD IS
LARGE AT THIS RANGE...SO CONFIDENCE IN THE EVOLUTION OF THE SYSTEM
IS LOW. TEMPS LOOK TO REMAIN SEASONABLE AHEAD OF THE SYSTEM...WITH
COOLING EXPECTED IN ITS WAKE BACK BELOW NORMAL.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
JR
AREA FORECAST DISCUSSION
NWS TULSA OK
412 PM CST FRI DEC 14 2012
.DISCUSSION...
AN INITIAL BAND OF SHOWERS IS MOVING ACROSS THE AREA AT THIS TIME.
THERE WILL THEN BE A RELATIVE LULL IN THE ACTIVITY LATE THIS
AFTERNOON AND EARLY THIS EVENING UNTIL A SECOND BAND OF SHOWERS
AND PERHAPS AN ISOLATED THUNDERSTORM OR TWO AFFECTS THE AREA LATER
THIS EVENING. THIS SECOND BAND WILL BE THE REMNANTS OF THE CURRENT
SEVERE SQUALL LINE ACROSS THE TEXAS PANHANDLE...WHICH WILL WEAKEN
AS IT MOVES INTO A MUCH MORE STABLE AIRMASS ACROSS CENTRAL AND
EASTERN OKLAHOMA.
HAVE KEPT THE ISOLATED THUNDER MENTION ACROSS PARTS OF NORTHEAST
OKLAHOMA AND ALSO ADDED ISOLATED THUNDER TO FAR SOUTHEAST
OKLAHOMA. THE HRRR SUGGESTS A SEPARATE CONVECTIVE LINE WILL FORM
ACROSS NORTHERN TEXAS LATER THIS EVENING WHERE INSTABILITY WILL BE
GREATEST...AND FAR SOUTHEAST OKLAHOMA MAY BE AFFECTED BY THIS LINE.
RAIN WILL END AND SKIES WILL BEGIN TO CLEAR LATE TONIGHT. SATURDAY
WILL BE A BREEZY AND WARM DAY WHICH WILL RAISE FIRE WEATHER
CONCERNS. AT THIS POINT...CONDITIONS LOOK LIKE THEY WILL REMAIN
JUST BELOW RED FLAG CRITERIA.
A WEAK COLD FRONT WILL KNOCK TEMPERATURES BACK A FEW DEGREES
SUNDAY AND MONDAY...BUT THEY WILL STILL BE WELL ABOVE THE SEASONAL
NORMALS. WEDNESDAY WILL SEE A RETURN TO UNSEASONABLY WARM
TEMPERATURES BEFORE A STRONGER COLD FRONT SWEEPS ACROSS THE AREA
LATER WEDNESDAY NIGHT RETURNING TEMPERATURES BACK TO NEAR NORMAL
IN ITS WAKE. LIMITED MOISTURE RETURN AHEAD OF THIS FRONT MEANS
THAT IT WILL LIKELY PASS THROUGH DRY.
STAYED CLOSE TO GUIDANCE TEMPERATURES THE NEXT COUPLE DAYS.
CURRENT READINGS AT A FEW SPOTS IN EASTERN OKLAHOMA ARE SLIGHTLY
BELOW THE FORECAST LOWS FOR TONIGHT DUE TO WET BULB COOLING WITH
THE RAIN...BUT READINGS SHOULD RECOVER SOME BEFORE THE 01Z
VERIFICATION START TIME.
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 47 68 38 62 / 90 10 10 10
FSM 45 71 43 68 / 80 10 10 10
MLC 47 70 43 67 / 80 10 10 10
BVO 44 67 33 60 / 90 10 10 10
FYV 45 66 39 61 / 80 10 10 10
BYV 46 66 40 61 / 80 10 10 10
MKO 46 69 39 64 / 90 10 10 10
MIO 46 66 37 59 / 90 10 10 10
F10 47 69 42 64 / 80 10 10 10
HHW 47 71 43 69 / 80 10 10 10
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&
$$
SHORT TERM...12
LONG TERM....05
PLATE
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1225 PM CST FRI DEC 14 2012
.AVIATION...
MVFR CONDITIONS REMAIN IN PLACE AT KCDS DUE TO STRATUS. KLBB HAS
MOMENTARILY COME UP TO VFR AS SKIES HAVE CLEARED ACROSS PORTIONS
OF THE SOUTH PLAINS...BUT BLOWING DUST WILL DAMPER VISIBILITIES
INTO THE MVFR OR PERHAPS IFR CATEGORY THIS AFTERNOON. A LINE OF
SHOWERS AND THUNDERSTORMS WILL MOVE FROM WEST TO EAST BEGINNING
EARLY-MID AFTERNOON. KLBB CAN EXPECT STORMS BEGINNING AFTER 21Z
WHILE KCDS WILL BE CLOSER TO 23Z WITH ALL ACTIVITY ENDING BY 02Z.
WINDS WILL VEER TO THE SOUTHWEST TO WEST AS THESE STORMS AND
ASSOCIATED FRONT MOVE THROUGH THIS AFTERNOON. SPEEDS WILL INCREASE
TO NEAR 35 KNOTS AT KLBB WITH GUSTS APPROACHING 50 KNOTS WHILE
KCDS WILL SEE RELATIVELY LOWER SPEEDS IN THE 20-25 KNOT RANGE WITH
GUSTS TO 30 KNOTS.
&&
.PREV DISCUSSION... /ISSUED 1102 AM CST FRI DEC 14 2012/
UPDATE...
FORECAST REMAINS INTACT FOR TODAY AS STRONG TO SEVERE
THUNDERSTORMS...HIGH WINDS...AND BLOWING DUST WILL ALL IMPACT
PORTIONS OF THE EXTREME SOUTHERN TEXAS PANHANDLE...SOUTH
PLAINS...AND ROLLING PLAINS.
SPRINKLES AND LIGHT SHOWERS WILL END BY LATE MORNING ACROSS
EXTREME EASTERN PORTIONS OF THE PANHANDLE AND ROLLING PLAINS.
VIGOROUS UPPER TROUGH MOVING INTO THE DESERT SOUTHWEST WILL CONTINUE
TO MOVE NORTHEAST TOWARD THE SOUTHERN PLAINS TODAY. SCATTERED TO
NUMEROUS THUNDERSTORMS WILL DEVELOP AHEAD OF THIS TROUGH ALONG A
PACIFIC FRONT AT THE SURFACE THIS AFTERNOON. CONVECTIVE
DEVELOPMENT LOOKS TO INITIATE AROUND 20-21Z NEAR THE TX/NM STATE
LINE AND RACE EAST ACROSS THE AREA BY WAY OF AN INTENSE WIND
FIELD CAPPED BY A 150+ KNOT JET AT H25. NEAR 40 KNOTS OF 0-1 KM
SHEAR WILL BE PRESENT ALONG THE FRONT AS IT MOVES THROUGH WITH
VECTORS NEAR PERPENDICULAR TO THE PACIFIC FRONT/DRYLINE. DAMAGING
WIND GUSTS WILL BE THE PRIMARY THREAT AS WEAKENING LAPSE RATES
ALOFT WILL LIMIT OVERALL HAIL POTENTIAL. A BRIEF TORNADO OR TWO
CANNOT BE RULED OUT IN ISOLATED LOW-TOPPED SUPERCELLS EITHER
GIVEN THE SUBSTANTIAL DEEP-LAYER SHEAR.
HIGH WIND WARNING WILL STAY IN EFFECT FROM 20-00Z MAINLY FROM
INTERSTATE 27 WEST AS SUBSIDENCE OCCURS BEHIND THE CONVECTIVE
LINE AND FRONT. MIXING TO AT LEAST H85 SHOULD BE ABLE TO OCCUR
AND BRING A PORTION OF THE 45-50 KNOT WINDS HERE DOWN TO THE
SURFACE. THIS SHOULD ALLOW FOR SOME AREAS TO SEE SUSTAINED WINDS
OF 40 MPH AT TIMES THIS AFTERNOON WITH GUSTS TO 58 MPH. THIS
GRADIENT FLOW MAY COMBINE WITH CONVECTIVE GUSTS AT TIMES TO ALSO
PRODUCE WINDS OF THIS MAGNITUDE. WITH WINDS THIS HIGH...SHOULD
ALSO SEE AREAS OF BLOWING DUST ON THE CAPROCK THIS AFTERNOON WHICH
MAY HINDER VISIBILITIES.
PREV DISCUSSION... /ISSUED 501 AM CST FRI DEC 14 2012/
SHORT TERM...
MULTI-FACETED AND EXCEPTIONALLY ACTIVE WEATHER FOR MID-DECEMBER
AWAITS THE SOUTH PLAINS LATER TODAY AS A VIGOROUS UPPER LOW LIFTS
NORTHEAST FROM NORTHERN BAJA IN THE FORM OF A NEGATIVELY TILTED
TROUGH. EARLY MORNING WATER VAPOR DEPICTION OF SAID LOW WAS QUITE
IMPRESSIVE AND FEATURED A DEEPENING PLUME OF SUBTROPICAL MOISTURE
AND SOME THUNDERSTORMS WELL IN ITS ADVANCE. ABUNDANT LOW-LEVEL
MOISTURE ADVECTION CONTINUED OVER WEST TX THIS MORNING AND WILL
ONLY CONTINUE THROUGH 18Z AS RESPECTABLE PRESSURE FALLS AROUND
7MB/6HR FOCUS IN ERN NM AHEAD OF THE EJECTING WAVE. THIS WILL KEEP
MOIST SOUTHERLY WINDS...STRATUS AND SOME FOG INTACT LONGER THAN
ORIGINALLY FORECAST BEFORE STRONG HEIGHT FALLS /60+ METERS AT
500MB/ UNFOLD BY EARLY AFTN ALONG THE NM-TX STATE LINE. ALONG WITH
A 135 KNOT UPPER SPEED MAX...A PACIFIC FRONT ACCOMPANYING THE
LEADING EDGE OF HEIGHT FALLS SHOULD EASILY SECURE DEEP ASCENT
WHILE PUTTING OUR SEASONABLY HIGH DEWPOINTS TO WORK.
CONSIDERING THE FLOW AHEAD OF THIS TROUGH IS MORE MERIDIONAL THAN
MODELS INDICATED JUST A FEW DAYS AGO...THE CHANCES OF A DRY FROPA
HAVE NOW GREATLY DIMINISHED. AFTERNOON POPS WERE DOUBLED NEARLY
AREA WIDE WITH JUST SLIGHT CHANCES OF MRNG SHOWERS CONFINED MAINLY
OFF THE CAPROCK WHERE DEEPER MOIST ADVECTION WITHIN A LLJ AXIS
COULD FAVOR VERY LIGHT PRECIP.
ALTHOUGH STRATUS WILL BE VERY SLOW TO ERODE...AMPLE MID-LEVEL
COOLING ACCOMPANYING THE UPPER TROUGH IS STILL SHOWN TO GARNER
WEAK SBCAPE AOB 600 J/KG BY 21Z WITH SURFACE TEMPS IN THE 50S-
60S. IT IS NOT UNCOMMON TO SEE SOME SEVERE CONVECTIVE MODES UNFOLD
IN SUCH LOW CAPE AND HIGH SHEAR ENVIRONMENTS PROVIDED
STRONG/FOCUSED ASCENT EMERGES. INITIAL SWODY1 ACCOUNTS FOR THIS
SCENARIO AND SEVERAL HI RES MODELS INCLUDING THE TTU-WRF DEPICT A
BROKEN LINE OF PARTICULARLY STRONG CELLS ACCOMPANYING FROPA. SUCH
A SCENARIO INVOLVING DMGG DOWNBURST WINDS OCCURRED HERE IN MID
DECEMBER 1993 FROM A SIMILAR SYNOPTIC PATTERN. AS WAS THE CASE
THEN...SEVERE WIND GUSTS WOULD BE THE DOMINANT THREAT WITH STORMS
TODAY AS STRONG KINEMATIC FLOW OVERSPREADS THE REGION. VERY MEAGER
CAPE IN THE HAIL GROWTH REGION SHOULD KEEP SEVERE HAIL PRODUCTION
AT BAY.
IN ADDITION TO A THREAT OF SEVERE CONVECTIVE WINDS...PATTERN
RECOGNITION BEHIND THE FRONT BY MID/LATE AFTERNOON DOES FAVOR AN
ABBREVIATED NON-CONVECTIVE HIGH WIND EVENT. A 500MB WIND MAX OF 100
KNOTS IS PROGGED TO OVERSPREAD OUR SWRN COUNTIES BY 21Z COMPLETE
WITH 60-70 KNOTS AT THE TOP OF THE MIXING LAYER AROUND 700MB OVER
MUCH OF THE CAPROCK. STRONG POST-FRONTAL SUBSIDENCE AND DRYING ON
SWLY WINDS SHOULD ALLOW FOR AN ABBREVIATED WINDOW OF 40G58 MPH
CONDITIONS OR HIGHER IMMEDIATELY FOLLOWING THE PACIFIC FRONT UNTIL
BOUNDARY LAYER DECOUPLING ENSUES BY 00Z. MOS GUIDANCE IS WELL
SHORT OF HIGH WIND CRITERIA...BUT WE BELIEVE MUCH OF THIS IS DUE
TO THE RELATIVELY SHORT DURATION OF HIGH WINDS THAT WE ANTICIPATE
WILL DEVELOP LATE IN THE DAY. TTU-WRF AND HRRR CONTINUE TO
CHAMPION SUCH CONDITIONS FOR A FEW HOURS FOLLOWING FROPA WITH
GUSTS AROUND 60 MPH TAKING AIM MAINLY WEST OF I-27.
LONG TERM...
ALTHOUGH WIND SPEEDS WILL DECREASE A BIT TONIGHT INTO SATURDAY
MORNING...EXPECT THEM TO ONCE AGAIN RAMP UP SOME SATURDAY
AFTERNOON AS ANOTHER APPROACHING SHORTWAVE TROF KEEPS A TIGHT
PRESSURE GRADIENT OVER THE REGION. SOIL WILL HAVE DRIED OUT SOME
FROM ANY RAINFALL TODAY AND CONDITIONS WILL ONCE AGAIN FAVOR SOME
AREAS OF BLOWING DUST SATURDAY AFTERNOON. THIS STORM SYSTEM WILL
RAPIDLY PUSH EAST SATURDAY NIGHT BEFORE ANOTHER TROF PUSHES OVER
THE AREA FOR SUNDAY AFTERNOON. THIS THIRD STORM SYSTEM WILL NOT BE
QUITE AS STRONG BUT WILL LIKELY RESULT IN BREEZY CONDITIONS AGAIN
FOR SUNDAY AFTERNOON. THROUGH THE WEEKEND...TEMPERATURES WILL ALSO
SLOWLY COOL AS CONTINUED COLD AIR ADVECTION TAKES PLACE KEEPING
READINGS CLOSE TO NORMAL FOR THIS TIME OF YEAR.
DRY WEATHER WILL BE EXPECTED FOR THE FIRST PART OF NEXT WEEK AS
DRY NORTHWESTERLY FLOW GRADUALLY TRANSITIONS TO SOUTHWESTERLY BY
MID-WEEK. THIS WILL ALLOW TEMPERATURES TO ONCE AGAIN CLIMB TO
ABOVE NORMAL THROUGH WEDNESDAY. ALSO BY MID-WEEK...ANOTHER
CANADIAN COLD FRONT WILL PUSH SOUTH THROUGH THE CENTRAL PLAINS
AND ARRIVE SOMETIME LATE WEDNESDAY INTO THURSDAY MORNING. THIS
FRONTAL PASSAGE SHOULD BE DRY AS LITTLE MOISTURE RECOVERY TAKES
PLACE BEFORE IT MOVES THROUGH. THIS FRONT WILL DROP TEMPERATURES
BACK DOWN TO NORMAL FOR THE END OF THE WEEK.
JORDAN
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 58 30 57 26 55 / 60 0 0 0 0
TULIA 60 33 59 28 55 / 60 0 0 0 0
PLAINVIEW 60 33 59 28 55 / 60 0 0 0 0
LEVELLAND 62 32 60 30 57 / 60 0 0 0 0
LUBBOCK 62 34 61 31 57 / 60 0 0 0 0
DENVER CITY 62 31 62 32 59 / 40 0 0 0 0
BROWNFIELD 63 33 62 31 59 / 50 0 0 0 0
CHILDRESS 62 40 65 34 61 / 60 20 0 0 0
SPUR 62 38 65 34 64 / 50 10 0 0 0
ASPERMONT 64 41 68 38 66 / 30 20 0 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL 6 PM CST THIS EVENING FOR THE FOLLOWING
ZONES: TXZ021>023-027>029-033>035-039>041.
&&
$$
31
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1102 AM CST FRI DEC 14 2012
.UPDATE...
FORECAST REMAINS INTACT FOR TODAY AS STRONG TO SEVERE
THUNDERSTORMS...HIGH WINDS...AND BLOWING DUST WILL ALL IMPACT
PORTIONS OF THE EXTREME SOUTHERN TEXAS PANHANDLE...SOUTH
PLAINS...AND ROLLING PLAINS.
SPRINKLES AND LIGHT SHOWERS WILL END BY LATE MORNING ACROSS
EXTREME EASTERN PORTIONS OF THE PANHANDLE AND ROLLING PLAINS.
VIGOROUS UPPER TROUGH MOVING INTO THE DESERT SOUTHWEST WILL CONTINUE
TO MOVE NORTHEAST TOWARD THE SOUTHERN PLAINS TODAY. SCATTERED TO
NUMEROUS THUNDERSTORMS WILL DEVELOP AHEAD OF THIS TROUGH ALONG A
PACIFIC FRONT AT THE SURFACE THIS AFTERNOON. CONVECTIVE
DEVELOPMENT LOOKS TO INITIATE AROUND 20-21Z NEAR THE TX/NM STATE
LINE AND RACE EAST ACROSS THE AREA BY WAY OF AN INTENSE WIND
FIELD CAPPED BY A 150+ KNOT JET AT H25. NEAR 40 KNOTS OF 0-1 KM
SHEAR WILL BE PRESENT ALONG THE FRONT AS IT MOVES THROUGH WITH
VECTORS NEAR PERPENDICULAR TO THE PACIFIC FRONT/DRYLINE. DAMAGING
WIND GUSTS WILL BE THE PRIMARY THREAT AS WEAKENING LAPSE RATES
ALOFT WILL LIMIT OVERALL HAIL POTENTIAL. A BRIEF TORNADO OR TWO
CANNOT BE RULED OUT IN ISOLATED LOW-TOPPED SUPERCELLS EITHER
GIVEN THE SUBSTANTIAL DEEP-LAYER SHEAR.
HIGH WIND WARNING WILL STAY IN EFFECT FROM 20-00Z MAINLY FROM
INTERSTATE 27 WEST AS SUBSIDENCE OCCURS BEHIND THE CONVECTIVE
LINE AND FRONT. MIXING TO AT LEAST H85 SHOULD BE ABLE TO OCCUR
AND BRING A PORTION OF THE 45-50 KNOT WINDS HERE DOWN TO THE
SURFACE. THIS SHOULD ALLOW FOR SOME AREAS TO SEE SUSTAINED WINDS
OF 40 MPH AT TIMES THIS AFTERNOON WITH GUSTS TO 58 MPH. THIS
GRADIENT FLOW MAY COMBINE WITH CONVECTIVE GUSTS AT TIMES TO ALSO
PRODUCE WINDS OF THIS MAGNITUDE. WITH WINDS THIS HIGH...SHOULD
ALSO SEE AREAS OF BLOWING DUST ON THE CAPROCK THIS AFTERNOON WHICH
MAY HINDER VISIBILITIES.
&&
.PREV DISCUSSION... /ISSUED 554 AM CST FRI DEC 14 2012/
AVIATION...
STRATUS...STRONG TSRA...HIGH WINDS...AND BLOWING DUST WILL MAKE
FOR DETERIORATING CONDITIONS TODAY. HIGH CONFIDENCE THAT MORNING
MVFR STRATUS WILL REMAIN LARGELY UNDISTURBED THROUGH EARLY
AFTERNOON. THIS LAYER MAY OCCASIONALLY DROP TO HIGH-END IFR
LEVELS BEFORE 16Z AT LBB...BUT A MUCH BETTER CHANCE OF IFR
CONDITIONS AT LBB WILL ACCOMPANY A FAST-MOVING COLD FRONT AROUND
22Z AS 30-40 KNOT SWLY WINDS REDUCE VISBYS TO 1SM OR LESS IN BLDU.
CDS SHOULD ESCAPE THESE EFFECTS...HOWEVER BOTH TERMINALS WILL
LIKELY SEE A BROKEN LINE OF TSRA ACCOMPANY THE FRONT COMPLETE WITH
LOCALLY DMGG WINDS. SUSPENDED DUST MAY LINGER FOR A FEW HOURS AT LBB
AFTER SUNSET WHEN WINDS SUBSIDE...BUT AS A WHOLE VFR CONDITIONS
SHOULD EMERGE BY EARLY EVENING AT BOTH STATIONS.
PREV DISCUSSION... /ISSUED 501 AM CST FRI DEC 14 2012/
SHORT TERM...
MULTI-FACETED AND EXCEPTIONALLY ACTIVE WEATHER FOR MID-DECEMBER
AWAITS THE SOUTH PLAINS LATER TODAY AS A VIGOROUS UPPER LOW LIFTS
NORTHEAST FROM NORTHERN BAJA IN THE FORM OF A NEGATIVELY TILTED
TROUGH. EARLY MORNING WATER VAPOR DEPICTION OF SAID LOW WAS QUITE
IMPRESSIVE AND FEATURED A DEEPENING PLUME OF SUBTROPICAL MOISTURE
AND SOME THUNDERSTORMS WELL IN ITS ADVANCE. ABUNDANT LOW-LEVEL
MOISTURE ADVECTION CONTINUED OVER WEST TX THIS MORNING AND WILL
ONLY CONTINUE THROUGH 18Z AS RESPECTABLE PRESSURE FALLS AROUND
7MB/6HR FOCUS IN ERN NM AHEAD OF THE EJECTING WAVE. THIS WILL KEEP
MOIST SOUTHERLY WINDS...STRATUS AND SOME FOG INTACT LONGER THAN
ORIGINALLY FORECAST BEFORE STRONG HEIGHT FALLS /60+ METERS AT
500MB/ UNFOLD BY EARLY AFTN ALONG THE NM-TX STATE LINE. ALONG WITH
A 135 KNOT UPPER SPEED MAX...A PACIFIC FRONT ACCOMPANYING THE
LEADING EDGE OF HEIGHT FALLS SHOULD EASILY SECURE DEEP ASCENT
WHILE PUTTING OUR SEASONABLY HIGH DEWPOINTS TO WORK.
CONSIDERING THE FLOW AHEAD OF THIS TROUGH IS MORE MERIDIONAL THAN
MODELS INDICATED JUST A FEW DAYS AGO...THE CHANCES OF A DRY FROPA
HAVE NOW GREATLY DIMINISHED. AFTERNOON POPS WERE DOUBLED NEARLY
AREA WIDE WITH JUST SLIGHT CHANCES OF MRNG SHOWERS CONFINED MAINLY
OFF THE CAPROCK WHERE DEEPER MOIST ADVECTION WITHIN A LLJ AXIS
COULD FAVOR VERY LIGHT PRECIP.
ALTHOUGH STRATUS WILL BE VERY SLOW TO ERODE...AMPLE MID-LEVEL
COOLING ACCOMPANYING THE UPPER TROUGH IS STILL SHOWN TO GARNER
WEAK SBCAPE AOB 600 J/KG BY 21Z WITH SURFACE TEMPS IN THE 50S-
60S. IT IS NOT UNCOMMON TO SEE SOME SEVERE CONVECTIVE MODES UNFOLD
IN SUCH LOW CAPE AND HIGH SHEAR ENVIRONMENTS PROVIDED
STRONG/FOCUSED ASCENT EMERGES. INITIAL SWODY1 ACCOUNTS FOR THIS
SCENARIO AND SEVERAL HI RES MODELS INCLUDING THE TTU-WRF DEPICT A
BROKEN LINE OF PARTICULARLY STRONG CELLS ACCOMPANYING FROPA. SUCH
A SCENARIO INVOLVING DMGG DOWNBURST WINDS OCCURRED HERE IN MID
DECEMBER 1993 FROM A SIMILAR SYNOPTIC PATTERN. AS WAS THE CASE
THEN...SEVERE WIND GUSTS WOULD BE THE DOMINANT THREAT WITH STORMS
TODAY AS STRONG KINEMATIC FLOW OVERSPREADS THE REGION. VERY MEAGER
CAPE IN THE HAIL GROWTH REGION SHOULD KEEP SEVERE HAIL PRODUCTION
AT BAY.
IN ADDITION TO A THREAT OF SEVERE CONVECTIVE WINDS...PATTERN
RECOGNITION BEHIND THE FRONT BY MID/LATE AFTERNOON DOES FAVOR AN
ABBREVIATED NON-CONVECTIVE HIGH WIND EVENT. A 500MB WIND MAX OF 100
KNOTS IS PROGGED TO OVERSPREAD OUR SWRN COUNTIES BY 21Z COMPLETE
WITH 60-70 KNOTS AT THE TOP OF THE MIXING LAYER AROUND 700MB OVER
MUCH OF THE CAPROCK. STRONG POST-FRONTAL SUBSIDENCE AND DRYING ON
SWLY WINDS SHOULD ALLOW FOR AN ABBREVIATED WINDOW OF 40G58 MPH
CONDITIONS OR HIGHER IMMEDIATELY FOLLOWING THE PACIFIC FRONT UNTIL
BOUNDARY LAYER DECOUPLING ENSUES BY 00Z. MOS GUIDANCE IS WELL
SHORT OF HIGH WIND CRITERIA...BUT WE BELIEVE MUCH OF THIS IS DUE
TO THE RELATIVELY SHORT DURATION OF HIGH WINDS THAT WE ANTICIPATE
WILL DEVELOP LATE IN THE DAY. TTU-WRF AND HRRR CONTINUE TO
CHAMPION SUCH CONDITIONS FOR A FEW HOURS FOLLOWING FROPA WITH
GUSTS AROUND 60 MPH TAKING AIM MAINLY WEST OF I-27.
LONG TERM...
ALTHOUGH WIND SPEEDS WILL DECREASE A BIT TONIGHT INTO SATURDAY
MORNING...EXPECT THEM TO ONCE AGAIN RAMP UP SOME SATURDAY
AFTERNOON AS ANOTHER APPROACHING SHORTWAVE TROF KEEPS A TIGHT
PRESSURE GRADIENT OVER THE REGION. SOIL WILL HAVE DRIED OUT SOME
FROM ANY RAINFALL TODAY AND CONDITIONS WILL ONCE AGAIN FAVOR SOME
AREAS OF BLOWING DUST SATURDAY AFTERNOON. THIS STORM SYSTEM WILL
RAPIDLY PUSH EAST SATURDAY NIGHT BEFORE ANOTHER TROF PUSHES OVER
THE AREA FOR SUNDAY AFTERNOON. THIS THIRD STORM SYSTEM WILL NOT BE
QUITE AS STRONG BUT WILL LIKELY RESULT IN BREEZY CONDITIONS AGAIN
FOR SUNDAY AFTERNOON. THROUGH THE WEEKEND...TEMPERATURES WILL ALSO
SLOWLY COOL AS CONTINUED COLD AIR ADVECTION TAKES PLACE KEEPING
READINGS CLOSE TO NORMAL FOR THIS TIME OF YEAR.
DRY WEATHER WILL BE EXPECTED FOR THE FIRST PART OF NEXT WEEK AS
DRY NORTHWESTERLY FLOW GRADUALLY TRANSITIONS TO SOUTHWESTERLY BY
MID-WEEK. THIS WILL ALLOW TEMPERATURES TO ONCE AGAIN CLIMB TO
ABOVE NORMAL THROUGH WEDNESDAY. ALSO BY MID-WEEK...ANOTHER
CANADIAN COLD FRONT WILL PUSH SOUTH THROUGH THE CENTRAL PLAINS
AND ARRIVE SOMETIME LATE WEDNESDAY INTO THURSDAY MORNING. THIS
FRONTAL PASSAGE SHOULD BE DRY AS LITTLE MOISTURE RECOVERY TAKES
PLACE BEFORE IT MOVES THROUGH. THIS FRONT WILL DROP TEMPERATURES
BACK DOWN TO NORMAL FOR THE END OF THE WEEK.
JORDAN
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 58 30 57 26 55 / 60 0 0 0 0
TULIA 60 33 59 28 55 / 60 0 0 0 0
PLAINVIEW 60 33 59 28 55 / 60 0 0 0 0
LEVELLAND 62 32 60 30 57 / 60 0 0 0 0
LUBBOCK 62 34 61 31 57 / 60 0 0 0 0
DENVER CITY 62 31 62 32 59 / 40 0 0 0 0
BROWNFIELD 63 33 62 31 59 / 50 0 0 0 0
CHILDRESS 62 40 65 34 61 / 60 20 0 0 0
SPUR 62 38 65 34 64 / 50 10 0 0 0
ASPERMONT 64 41 68 38 66 / 30 20 0 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING FROM 2 PM THIS AFTERNOON TO 6 PM CST THIS
EVENING FOR THE FOLLOWING ZONES:
TXZ021>023-027>029-033>035-039>041.
&&
$$
31