Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/15/12
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
411 AM PST THU DEC 13 2012
.SHORT TERM DISCUSSION...
IR SATELLITE IMAGERY SHOWS UPPER LOW NOW CENTERED ROUGHLY OVER THE
SIERRA FOOTHILLS THIS MORNING. SHORTWAVE DISTURBANCES ROTATING
AROUND THIS LOW BROUGHT A FEW SHOWERS OVER THE SIERRA AND FOOTHILLS
OVER NIGHT WITH SNOW LEVELS DROPPING SNOW DOWN TO THE 2500 FOOT
LEVEL. ONE DISTURBANCE ROTATING AROUND THE BASE OF THE LOW BROUGHT A
FEW SHOWERS TO THE SOUTHERN SACRAMENTO VALLEY. THESE SHOWERS SHOULD
DISSIPATE WITHIN THE NEXT FEW HOURS. OVERALL...CWA WILL REMAIN UNDER
PARTLY CLOUDY SKIES TODAY. THERE HAS BEEN ENOUGH CLEARING IN SOME
AREAS FOR SOME AREAS OF MORNING FOG. SOME RAP AROUND MOISTURE COULD
KEEP A FEW SHOWERS GOING OVER THE NORTHERN SIERRA THROUGH THE DAY.
THE UPPER LOW AND ASSOCIATED TROUGH IS FORECAST TO SHIFT EAST OF THE
STATE BY THIS EVENING WITH NORTHERLY FLOW DEVELOPING OVER THE
NORTHERN HALF OF THE STATE. THURSDAY NIGHT LOOKS DRY UNDER
SMALL SCALE RIDGING. A PACIFIC FRONT NOW IN THE GULF OF ALASKA WILL
DROP QUICKLY TOWARDS THE NORCAL COAST THURSDAY NIGHT. MODELS ARE
STILL INDICATING THAT THIS SYSTEM WILL SPLIT AS IT MOVES INLAND.
MODELS VARY ON THE EXACT PATH OF THE SOUTHERN PORTION OF THIS SYSTEM
BUT IN GENERAL THIS LOW DROPS SOUTHWARD. MODELS VARY ON AMOUNT OF
PRECIP OVER THE FORECAST AREA WITH ECMWF KEEPING MOST PRECIP OFF THE
COAST WHILE GFS AND GEM BRING LARGER THREAT OF PRECIP INLAND. EITHER
WAY...PRECIP AMOUNTS REMAIN ON THE LIGHT SIDE. BRIEF RIDGING FRIDAY
NIGHT WITH A RE-CONSOLIDATION OF THE PACIFIC STORM TRACK BACK INTO
THE PACIFIC NORTHWEST BY SATURDAY AFTERNOON. THEREFORE...LOOKS LIKE
FIRST PORTION OF UPCOMING WEEKEND WILL BE MAINLY DRY OVER THE REGION
WITH A RETURN TO A WETTER PERIOD FOR THE SECOND PORTION AND GOING
INTO NEXT WEEK. QPF VALUES FOR THIS SYSTEM LOOK A LITTLE LARGER THAN
FOR THE PREVIOUS COUPLE BUT STILL FAIRLY LOW COMPARED TO THE LARGER
STORMS EARLIER THIS MONTH.
.EXTENDED DISCUSSION (MONDAY THROUGH THURSDAY)
UNSETTLE PATTERN PERSISTS DURING THE EXTENDED FORECAST WHERE
WEATHER WILL YO-YO BETWEEN PERIODS OF RAIN/SNOW AND DRY
CONDITIONS. TIMING OF THE WET PERIODS HAS NOT BEEN CONSISTENT IN
THE MODEL RUNS. THE MOST RECENT GFS & ECMWF RUNS INDICATE A
WAVE ON MONDAY INTO TUESDAY...DRIER ON WEDNESDAY WITH LINGERING
ISOLATED SHOWERS POSSIBLE. THEN THE NEXT WAVE ARRIVING LATE
WED/EARLY THURSDAY. HAVE KEPT A SLIGHT CHANCE TO CHANCE OF
PRECIPITATION THROUGHOUT THE EXTENDED FORECAST. SNOW LEVELS WILL
BE FAIRLY LOW AS COLD AIR ALOFT STREAMS OVER THE REGION...
GENERALLY BETWEEN 2000-4000 FEET. JBB
&&
.AVIATION...
PARTLY CLOUDY SKIES CONTINUE DURING THE MORNING HOURS WITH SCT-
BKN-OVC MID TO HIGH LEVEL CLOUDS. NEAR THE SURFACE...SOME FOG/LOW LEVEL
STRATUS HAS BEEN DEVELOPING IN PORTIONS OF THE NORTHERN SAN
JOAQUIN VALLEY AND COULD SPREAD INTO THE SOUTHERN SACRAMENTO
VALLEY WITH VSBYS RANGING LIFR UP TO MVFR THROUGH ABOUT 16Z THIS MORNING.
LIGHT WINDS OVER THE AREA DURING THE NEXT 24 HRS.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
1050 AM EST Thu Dec 13 2012
.NEAR TERM [Through Tonight]...
15z CONUS NAM/Regional RAP analysis depict the mid-level shortwave
trough axis positioned north to south along the Mid-Atlantic
states. Locally, subsidence on the back side of the wave has
resulted in very dry air spreading through the upper/middle levels
of the atmosphere. At the surface, northeasterly flow between a
developing low in the western Atlantic, and high pressure spanning
the entire eastern third of the country, is providing a continuous
low level moisture feed to the Southeast. As a result, low clouds
currently hold a firm grip on the Tri-State region. This mornings
KTAE sounding indicates that the saturated layer is about 3000 ft
deep. With the subsidence inversion atop the moist layer, and very
little insolation due to the thick, continuous nature of the
stratus deck, it is likely that the clouds will stick around for
much, if not all of the day. This is especially true for the
Tallahassee and Valdosta areas, whereas communities near Dothan,
Albany, and Panama City may break out along the edge of the cloud
deck later today. It is likely that the drizzle experienced this
morning has ended for most locations, and the main impact of the
cloud cover will be to keep chilly temperatures in the forecast
all afternoon. Expect all locations throughout the Tri-State
region to remain below 60 degrees today, with areas under the
thickest cloud cover hovering in the lower 50s.
At this point, all indications are that the low clouds will linger
through the overnight hours tonight.
&&
.SHORT TERM [Friday Through Saturday]...
Deep layer ridging firmly in place Friday with seasonal afternoon
temps and dry conditions. Temps won`t be as cold Friday night as
winds swing around to the east and mid to upper level clouds spread
in from the west ahead of the next low pressure system. Saturday
will be a day of transition as the upper ridge flattens and the
surface ridge weakens allowing a cold front to edge closer to our
CWA. Clouds will further increase throughout the CWA but only a
slight chance for rain across SE Alabama in the afternoon.
Temperatures will elevate above seasonal levels as winds shifting to
the southeast and south.
&&
.LONG TERM [Saturday Night through next Thursday]...
We continue to see model to model and run to run inconsistencies
with respect to the evolution of the upper level flow pattern and
associated frontal systems through the mid/long range periods.
Confidence in this part of the forecast remains below average. We
generally used a blend of HPC guidance and gridded MOS for most
fields. Details will need to be resolved later, but the general
trend shows a retreating ridge at the start of the period which
brings another day of warm temps on Sunday. A frontal system will
approach from the west. Chance PoPs (30-50%) were used with
highest northwest. As short wave energy moves from the Southern
Plains out into the Mid South, a wave develops on the front and
highest PoPs (40-60%) are realized on Monday as the front moves
through. We generally followed the GFS solution after that with
high pressure building eastward along the Gulf Coast in the wake
of the front. Since this air mass is of Pacific origin, temps will
generally be close to average behind the cold front. The next
frontal system is progged to approach on Thursday.
It should be noted that the 12/12Z Euro was much less progressive
and showed a deepening trough with a massive coastal low bombing
along the Southeast U.S. coast on Tuesday. The latest 00Z Euro is
closer to our preferred solution, at least in terms of sensible
weather locally.
&&
.AVIATION [Beginning 16Z Thursday]...
Low end MVFR to high end IFR ceilings prevail at all terminals as
of 16z. It is possible that KABY and KDHN will scatter out to VFR
conditions later this afternoon. Elsewhere, MVFR ceilings are
expected for the remainder of the day. Low clouds will likely
linger overnight, and updated restrictions will be re-introduced
with the 18z TAF.
&&
.MARINE...
Cautionary conditions over the coastal waters should gradually drop
below these levels later this afternoon as the pressure gradient
slowly weakens. Then, we expect winds and seas to remain below
headline criteria through the weekend as winds gradually veer from
northeast to southwest. Winds may reach advisory levels Sunday Night
into Monday with the approach and passage of a strong cold front.
&&
.FIRE WEATHER...
Relative humidity is expected to remain above critical levels
through much of the next week.
&&
.HYDROLOGY...
No river rises of any significance are expected at this time.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 54 39 66 46 71 / 10 0 0 0 10
Panama City 58 43 65 52 69 / 10 0 0 0 10
Dothan 58 38 63 46 68 / 10 0 0 0 10
Albany 56 36 64 44 68 / 10 0 0 0 10
Valdosta 53 40 65 45 71 / 0 0 0 0 10
Cross City 56 42 71 48 76 / 0 0 0 0 10
Apalachicola 58 43 64 51 69 / 10 0 0 0 10
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Harrigan
SHORT TERM...Barry
LONG TERM...Wool
AVIATION...Harrigan
MARINE...Gould
FIRE WEATHER...Wool
HYDROLOGY...Harrigan
AREA FORECAST DISCUSSION
NWS MIAMI FL
101 AM EST THU DEC 13 2012
.AVIATION...
THE MAIN CONCERN FOR THE EARLY MORNING HOURS WILL BE LOW CEILING
AND VISIBILITY RESTRICTIONS WITH THE CAVEAT THAT THERE IS A LOT OF
UNCERTAINTY. REGIONAL OBSERVATIONS INDICATE FOG AND MIST ACROSS
CENTRAL AND WEST CENTRAL PORTIONS OF THE PENINSULA WITH
IFR VISIBILITY RESTRICTIONS. AND THE CURRENT GUIDANCE IS STRONGLY
HINTING AT LOW STRATUS AND/OR FOG DURING THE EARLY MORNING HOURS
TODAY. FOR NOW WENT ALONG WITH PREVIOUS TAF`S SUGGESTING CEILINGS
NEAR 1500 FT STARTING AROUND 09Z BUT GUIDANCE INDICATED CEILINGS
NEAR 700 FEET POSSIBLE. WILL AMEND AS NECESSARY BUT PERIODS OF IFR
CONDITIONS MAY BE POSSIBLE EARLY THIS MORNING.
60
&&
.PREV DISCUSSION... /ISSUED 1001 PM EST WED DEC 12 2012/
UPDATE...
THE EVENING SURFACE ANALYSIS SHOWED A FRONTAL BOUNDARY EXTENDING
SOUTHWEST ACROSS THE FLORIDA PENINSULA NORTH OF OUR LOCAL AREA AND
A DECENT DEWPOINT GRADIENT FROM NORTH TO CENTRAL FLORIDA.
OBSERVATIONS SHOWED MAINLY LIGHT SOUTH-SOUTHWEST FLOW SOUTH OF THE
BOUNDARY ACROSS SOUTH FLORIDA WITH DEWPOINTS RANGING FROM THE
UPPER 60S TO LOWER 70S. RECENTLY ANIMATED WATER VAPOR LOOP SHOWED
A FAIRLY STRONG SHORTWAVE TROUGH BEGINNING TO LIFT NORTHEAST
TOWARD THE CAROLINAS WITH PLENTY OF MID/UPPER MOISTURE SPREADING
NORTHEAST ACROSS THE STATE...WITH THE EXCEPTION BEING THE FLORIDA
PANHANDLE WHERE DRY AIR HAS BEGUN SPREAD EAST IN THE WAKE OF THE
SHORTWAVE TROUGH. THE LATEST RUC ANALYSIS HAS INITIALIZED WELL
WITH THESE SYNOPTIC FEATURES AND GENERALLY INDICATES THE FRONTAL
BOUNDARY CONTINUING TO SLOWLY MAKE ITS WAY SOUTH INTO OUR AREA
THROUGH THE REMAINDER OF THE NIGHT AND INTO THURSDAY. LIGHT WINDS
ALONG WITH THE POTENTIAL FOR SOME CLEARING COULD RESULT IN FOG
DEVELOPMENT THROUGH THE LATE NIGHT HOURS. THE LATEST SREF
PROBABILITIES REFLECT THIS POTENTIAL AND REMAIN QUITE AGGRESSIVE
INDICATING VISIBILITIES DROPPING TO LESS THAN A MILE AFTER 06Z AND
CONTINUING THROUGH DAYBREAK ACROSS THE INLAND LOCATIONS. THE
LATEST FORECAST PACKAGE WAS UPDATED...MAINLY TO REDUCE THE RAIN
CHANCES THIS EVENING. OTHERWISE...THE PREVIOUS FORECAST PACKAGE
REMAINS ON TRACK WITH NO OTHER UPDATES NECESSARY AT THIS TIME.
85/AG
PREV DISCUSSION... /ISSUED 641 PM EST WED DEC 12 2012/
AVIATION...WEAK COLD FRONT WILL MOVE ACROSS SOUTH FLORIDA EARLY
THURSDAY WITH EXTENSIVE CLOUD FIELD AHEAD OF THE FRONT. VERY
LITTLE SHRA ACTIVITY WITH ABUNDANT MID LEVEL DRY AIR. GUIDANCE
INDICATED IFR CIGS DEVELOPING AFT 06-08Z BUT CONFIDENCE NOT HIGH
ENOUGH TO GO WITH THAT BUT SSW-SW LIGHT WIND FLOW LESS THAN 5 KT
GIVES MORE CREDENCE TO THIS SET UP SO INTRODUCED MVFR CIGS
PERSISTING TO BTWN 13-15Z. SFC WIND WILL SHIFT TO THE NNW BEHIND
THE FRONT AT 8-10KT EARLY THURSDAY AND WILL ATTEMPT TO VEER TO THE
NNE LATE IN THE PERIOD. SO AT THIS TIME, ONLY INDICATED THIS AT KFLL.
KOB
PREV DISCUSSION... /ISSUED 308 PM EST WED DEC 12 2012/
A FEW STRONG STORMS ARE POSSIBLE NORTH OF ALLIGATOR ALLEY THIS
AFTERNOON INTO EARLY THIS EVENING...
DRIER AND COOLER WEATHER IS EXPECTED FOR LATE THIS WEEK INTO
THIS WEEKEND...
SHORT TERM...
A COLD FRONT OVER CENTRAL FLORIDA WILL CONTINUE TO MOVE SLOWLY
SOUTH THIS AFTERNOON AND SHOULD BE AROUND THE LAKE OKEECHOBEE AREA
TONIGHT. THIS WILL KEEP THE STEERING FLOW SOUTHWEST OVER THE CWA
THIS AFTERNOON AND KEEP THE DEEP TROPICAL MOISTURE IN PLACE.
AT THE SAME TIME...THE SHORTWAVE OVER THE EASTERN GULF OF MEXICO
WILL CONTINUE TO MOVE EAST THROUGH CENTRAL/SOUTH FLORIDA THIS
AFTERNOON. THESE TWO WEATHER SYSTEMS ALONG WITH THE DEEP TROPICAL
MOISTURE WILL ALLOW FOR SCATTERED SHOWERS AND THUNDERSTORMS TO
DEVELOP OVER MOST OF THE CWA THIS AFTERNOON INTO THIS EVENING WITH
THE HIGHEST CHANCE OVER THE LAKE OKEECHOBEE AREA.
THE 500 MB LEVEL OF THE ATMOSPHERE CONTINUES TO BE IN THE -9C TO
-10C FROM THE SPECIAL 18Z MIA SOUNDING THIS AFTERNOON. THIS SHOULD
ALLOW FOR A FEW STRONG STORMS TO DEVELOP THROUGH THE AFTERNOON AND
EARLY EVENING HOURS...ESPECIALLY AROUND THE LAKE OKEECHOBEE AND
NORTHEAST AREAS OF THE CWA. SO WILL CONTINUE TO MENTION STRONG
STORM WORDING IN THE HWO PRODUCT AND THE NORTHERN ZONES OF THE CWA
FOR THIS AFTERNOON INTO EARLY THIS EVENING.
PATCHY TO AREAS OF FOG ARE ALSO POSSIBLE OVER SOUTH FLORIDA
TONIGHT AHEAD OF THE COLD FRONT...AS THE WINDS WILL BE LIGHT FROM
THE SOUTHWEST ALONG WITH THE DEEP TROPICAL MOISTURE. SO WILL BE
ADDING FOG WORDING TO MOST OF THE CWA FOR LATE TONIGHT INTO EARLY
THURSDAY MORNING.
THURSDAY INTO THIS WEEKEND...
THE COLD FRONT OVER LAKE OKEECHOBEE WILL CONTINUE TO MOVE
SOUTHWARD THROUGH THE CWA THURSDAY MORNING AND INTO THE FLORIDA
KEYS THURSDAY AFTERNOON INTO THURSDAY NIGHT. THIS WILL ALLOW FOR
DRIER AIR TO START TO WORK INTO THE CWA FROM THE NORTH.
HOWEVER...THERE COULD STILL BE A FEW SHOWERS THAT COULD AFFECT THE
EAST COAST METRO AREAS ON THURSDAY. SO WILL CONTINUE THE SLIGHT
CHANCE OF POPS FOR THE EAST COAST METRO AREAS ON THURSDAY...BEFORE
GOING DRY FOR ALL OF SOUTH FLORIDA THURSDAY NIGHT. THE DRY WEATHER
WILL THEN CONTINUE TO REMAIN IN PLACE OVER SOUTH FLORIDA THIS
WEEKEND...AS HIGH PRESSURE BUILDS INTO THE SOUTHEAST UNITED STATES
FROM THE CENTRAL UNITED STATES.
TEMPERATURES WILL ALSO GET BACK TO MORE NEAR NORMAL CONDITIONS
OVER SOUTH FLORIDA THIS WEEKEND WITH HIGHS IN THE 70S TO AROUND 80
AND LOWS IN THE 50S INTERIOR AREAS TO 60S OVER THE METRO AREAS.
LONG TERM...
THE LONG RANGE MODELS CONTINUE TO SHOW A LOW PRESSURE DEVELOPING
IN THE CENTRAL UNITED STATES EARLY NEXT WEEK...BEFORE MOVING INTO
THE SOUTHEAST UNITED STATES BY MIDDLE OF NEXT WEEK. THE MODELS ARE
ALSO SHOWING THAT A STRONG COLD FRONT ASSOCIATED WITH THE LOW WILL
BE MOVING THROUGH SOUTH FLORIDA ON TUESDAY. HOWEVER...THE MODELS
ARE NOW SHOWING THAT MOST OF THE ENERGY WILL NOT BE MORE CLOSER TO
THE LOW AND NOT ALONG THE FRONT. SO WILL KEEP THE SLIGHT CHANCE OF
SHOWERS IN THE FORECAST FOR TUESDAY.
MARINE...
THE WINDS OVER THE LOCAL SOUTH FLORIDA WATERS WILL BE SOUTHERLY
THIS AFTERNOON INTO TONIGHT...BEFORE SWINGING TO A NORTHERLY
DIRECTION THURSDAY INTO FRIDAY. THE SPEEDS WILL ALSO INCREASE FROM
10 TO 15 KNOTS TONIGHT TO 15 TO 20 KNOTS THURSDAY AFTERNOON INTO
FRIDAY. THIS WILL ALLOW FOR THE ATLANTIC SEAS TO INCREASE FROM 2
TO 3 FEET TONIGHT UP TO AROUND 7 FEET BY THURSDAY NIGHT INTO
FRIDAY. THE GULF SIDE SEAS WILL REMAIN BELOW 6 FEET TONIGHT INTO
FRIDAY. SO A SCEC AND OR SCA WILL MORE LIKELY BE NEEDED BY
THURSDAY AFTERNOON INTO THURSDAY NIGHT FOR THE LOCAL WATERS OF
SOUTH FLORIDA.
FIRE WEATHER...
THE RELATIVE HUMIDITIES OVER SOUTH FLORIDA WILL REMAIN ABOVE THE
35 PERCENT CRITICAL VALUE FOR REST OF THE WEEK INTO THIS WEEKEND.
SO NO PROBLEMS ARE EXPECTED WITH THE FIRE WEATHER PRODUCTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 76 64 78 65 / 20 10 10 10
FORT LAUDERDALE 78 66 78 67 / 20 10 10 10
MIAMI 79 67 79 66 / 20 10 10 10
NAPLES 76 58 77 59 / 10 - - -
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...23/SK
AVIATION/RADAR...60/BD
AREA FORECAST DISCUSSION
NWS DES MOINES IA
650 PM CST FRI DEC 14 2012
.UPDATE...
HAVE UPDATED THE FORECAST TO MAINLY DELAY PRECIP ONSET ACROSS THE
AREA WITH MUCH OF THE AREA NOT EXPECTED TO SEE PRECIP UNTIL CLOSER
TO 05Z OR LATER. OTHERWISE DID NOT MAKE ANY OTHER CHANGES...WITH
REMAINDER OF FORECAST ON TRACK AT THIS POINT.
.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...15/00Z
VFR CONDITIONS EXPECTED FOR THE FIRST 6 HOURS OF THE TAF...WITH CIGS
AROUND SCT-BKN040 SLOWLY PROGRESSING NORTHWARD IN ADVANCE OF THE
WEATHER SYSTEM LOCATED OVER THE OK/TX PANHANDLES. AS THIS SYSTEM
MOVES NORTHEASTWARD INTO IOWA BY SATURDAY MORNING...RAIN AREA
EXPECTED TO SPREAD NORTHEASTWARD ACROSS THE CWA LATE TONIGHT. HAVE
PUSHED PRECIP ONSET BACK A COUPLE HOURS AT MOST SITES...WITH LOW
LEVEL MOISTURE/SYSTEM TIMING COMING IN A BIT SLOWER. COULD SEE SOME
MVFR VSBYS/CIGS WITHIN THE RAIN AREA. POSSIBILITY OF SOME IFR CIGS
ARE PRESENT AT TIMES THROUGHOUT THE PERIOD...BUT UNCERTAINTY IS HIGH
SO HAVE NOT INCLUDED FOR NOW.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
UPDATE...MJB
SHORT TERM...KS
AVIATION...MJB
LONG TERM...JOHNSON
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
614 PM CST FRI DEC 14 2012
.AVIATION...
FLIGHT CONDITIONS WILL DETERIORATE TONIGHT AS A STORM OVER
EASTERN COLORADO MOVES NORTHEAST INTO EASTERN NEBRASKA BY
SATURDAY MORNING. RAIN WILL SPREAD NORTHEAST OVER THE AREA TONIGHT.
MVFR CIGS AND VSBYS WILL DEVELOP LATE THIS EVENING OR EARLY
SATURDAY MORNING WITH WITH WIDESPREAD IFR CONDITIONS EXPECTED LATE
TONIGHT OR SATURDAY MORNING. IFR CONDITIONS WILL REMAIN OVER THE
AREA THROUGH 6 PM CDT SATURDAY. AT THIS TIME IT APPEARS THAT
THUNDERSTORMS WITH THIS SYSTEM WILL NOT MAKE IT AS FAR NORTH AS
EASTERN IA AND NORTHWEST ILLINOIS. SOUTH TO SOUTHEAST WINDS WILL
BE INCREASING LATE TONIGHT WITH GUSTS OF 20 TO 25 KNOTS EXPECTED
LATE TONIGHT AND SATURDAY.
DLF
&&
.PREV DISCUSSION... /ISSUED 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
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
530 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...15/00Z
VFR CONDITIONS EXPECTED FOR THE FIRST 6 HOURS OF THE TAF...WITH CIGS
AROUND SCT-BKN040 SLOWLY PROGRESSING NORTHWARD IN ADVANCE OF THE
WEATHER SYSTEM LOCATED OVER THE OK/TX PANHANDLES. AS THIS SYSTEM
MOVES NORTHEASTWARD INTO IOWA BY SATURDAY MORNING...RAIN AREA
EXPECTED TO SPREAD NORTHEASTWARD ACROSS THE CWA LATE TONIGHT. HAVE
PUSHED PRECIP ONSET BACK A COUPLE HOURS AT MOST SITES...WITH LOW
LEVEL MOISTURE/SYSTEM TIMING COMING IN A BIT SLOWER. COULD SEE SOME
MVFR VSBYS/CIGS WITHIN THE RAIN AREA. POSSIBILITY OF SOME IFR CIGS
ARE PRESENT AT TIMES THROUGHOUT THE PERIOD...BUT UNCERTAINTY IS HIGH
SO HAVE NOT INCLUDED FOR NOW.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...KS
AVIATION...MJB
LONG TERM...JOHNSON
AREA FORECAST DISCUSSION...UPDATED
NWS TOPEKA KS
543 PM CST FRI DEC 14 2012
...UPDATE TO AVIATION...
.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
&&
.AVIATION...
UPPER TROUGH WILL LIFT OUT ACROSS THE TAF SITES THROUGH THE NIGHT
WITH SHOWERS INCREASING AND CIGS LOWERING TO 1000-2000 FEET WITH
GUSTY SOUTH WINDS TO 25 KTS. ALTHOUGH THUNDER CANNOT BE RULED
OUT...CONFIDENCE ON ITS OCCURRENCE NEAR ANY TERMINAL AND ITS
TIMING REMAINS TOO LOW TO INSERT INTO TAFS AT THIS TIME....BUT WILL
NEED TO BE MONITORED. AS DRY SLOT MOVES THROUGH BETWEEN 09Z AND
12Z...EXPECT RAIN TO DIMINISH BUT MVFR CIGS CONTINUING...ALTHOUGH
STILL GRADUALLY RISING THROUGH THE DAY. AS THIS OCCURS...GUSTY
WINDS WILL DECREASE AS WELL TO 10 TO 15 KTS AND VEER TO THE
SOUTHWEST.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
534 PM CST FRI DEC 14 2012
...UPDATED FOR THE 00Z AVIATION DISCUSSION...
.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 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 527 PM CST FRI DEC 14 2012
MVFR CIGS AND VSBYS WILL DOMINATE THE TAFS THROUGH ABOUT 04 TO
06Z, WHEN FLIGHT CONDITIONS WILL IMPROVE. A SHORT WAVE IS MOVING
NORTHEAST THROUGH THE TAF SITES RATHER QUICKLY, AND MAY BRING IFR
CIGS FOR A SHORT TIME AS A CONVECTIVE CELL MOVES OVER A TAF SITE.
WINDS WILL BE SOUTH TO SOUTHEAST AT 15G20KTS EARLY, THEN BECOME
SOUTHWEST AT 13G23KTS BEHIND THE UPPER WAVE. A COLD FRONT WAS
MOVING NORTH-NORTHEAST THROUGH FAR SOUTHWESTERN KANSAS AT 5:30 PM,
AND SHOULD MARCH THROUGH GCK AROUND 03Z, THROUGH DDC ABOUT 04Z,
AND PASS HYS AROUND 06Z. THE FRONTAL PASSAGE IS THE BEST TIME FOR
ANY CONVECTION AT EACH TAF SITE.
&&
.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...BURKE
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1050 AM MST THU DEC 13 2012
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 158 AM MST THU DEC 13 2012
04Z WATER VAPOR IMAGERY AND RAP ANALYSIS INDICATED LOW AMPLITUDE H5
RIDGE IN PLACE ACROSS THE REGION WITH STRONG TROUGH ALONG AND JUST
OF THE WEST COAST. THIS SYSTEM WILL PLAY A LARGE ROLE ON EXPECTED
WEATHER THROUGH THE START OF THE WEEKEND...AND IS STILL NOT TOTALLY
BEING SAMPLED BY UPPER AIR NETWORK. 00Z SOUNDINGS INDICATED A DRY
AND MUCH WARMER AIRMASS THAN 24 HOURS AGO...WITH STRONGEST WARMING
BETWEEN H8 AND H6. AT THE SFC...TROUGH AXIS WAS IN PLACE ALONG
ROUGHLY A KLBF TO KTRB LINE.
MAIN FORECAST CONCERNS WILL BE SKY COVER THIS MORNING AND TONIGHT
DUE TO GEMINID METEOR SHOWER AND PRECIPITATION POTENTIAL FRIDAY.
TODAY-TONIGHT...SHORT WAVE RIDGING WILL CONTINUE ACROSS THE AREA
THROUGH THE EVENING AND ALTHOUGH WEAK AMPLITUDE WILL NOT CREATE ANY
STRONG SUBSIDENCE DRY AND STABLE CONDITIONS EXPECTED SO ANY WEAK
ASCENT WILL NOT HAVE MUCH OF AN IMPACT ON SENSIBLE WEATHER. ALREADY
SEEING A LOT OF CIRRUS MOVING OVER THE AREA...WITH 80-90KT H3 WINDS
HELPING INDUCE CIRRUS DOWNSTREAM OF THE MOUNTAINS. GIVEN EXPECTED
FLOW ALOFT...EXPECT CLOUD COVER TO PERSIST THROUGH THE MORNING HOURS
WHICH WILL LIKELY INHIBIT THE VIEWING OF METEOR SHOWER IN SOME
LOCATIONS. SKIES WILL CLEAR DURING THE AFTERNOON AS FLOW ALOFT
BECOMES LESS PERPENDICULAR TO MOUNTAINS AND RRQ OF H3 JET STREAK
SHIFT TO THE NORTH AND EAST ACROSS SOUTH DAKOTA. WHILE CIRRUS WILL
LINGER ACROSS NORTHERN CWA TONIGHT...SHOULD BE A FEW PERIODS WHERE
CLOUDS CLEAR UP ALTHOUGH CLOUD COVER WILL BEGIN TO INCREASE RAPIDLY
FROM THE SOUTHWEST AFTER 2 AM MST (3 AM CST) AS NEXT SYSTEM
APPROACHES.
FRIDAY...MUCH MORE ACTIVE WEATHER IS EXPECTED ACROSS THE CWA ON
FRIDAY AS STRONG TROUGH BEGINS TO MOVE OVER THE AREA. MODELS HAVE
COME INTO MUCH BETTER AGREEMENT WITH TIMING OF FAIRLY PROGRESSIVE
TROUGH ACROSS THE PLAINS...ALTHOUGH LOOKING AT THE INDIVIDUAL
DYNAMIC TROP ANALYSIS FROM THE GFS AND NAM...AM A LITTLE CONCERNED
WITH GFS DEPICTING A MUCH LESS CONSOLIDATED PV ANOMALY WHICH OFTEN
TENDS TO HINDER WIDESPREAD PERSISTENT PRECIPITATION RATHER THAN HELP.
WHILE THE POSSIBILITY OF TROUGH COMING OUT IN PIECES LOWERS
CONFIDENCE SOMEWHAT...ENOUGH AGREEMENT BETWEEN OPERATIONAL MODELS TO
SUPPORT PROBABLY ONE OF THE BETTER CHANCES FOR PRECIP OVER THE PAST
MONTH AND BASED ON ALL FACTORS THINK 30-60 PROBABILITIES WARRANTED.
BEST CHANCES WILL BE ACROSS EASTERN CWA WHERE ISENTROPIC ANALYSIS
INDICATES STRONGEST MOISTURE TRANSPORT IN THIS AREA WITH A SECOND
MAXIMUM IN FORCING LOCATED TO NORTH OF SFC WARM FRONT IN NORTHWEST
CWA. DEPENDING ON HOW QUICKLY CLEARING OCCURS ONCE DRY SLOT
CIRCULATION BEGINS TO ENTER CWA COULD POSSIBLY SEE A SFC BASED
THUNDERSTORM ALONG DRY LINE IN SOUTHEASTERN ZONES AROUND SUNSET.
WHILE THERE IS SOME DATA SUGGESTING A CHANGE OVER TO SNOW IS
POSSIBLE IN THE WEST DURING THE AFTERNOON...AM GOING TO LEAN TOWARDS
A CONSENSUS OF AVAILABLE DATA AND HOLD OFF ON ANY COMPLETE CHANGE
OVER UNTIL AFTER 00Z.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 158 AM MST THU DEC 13 2012
FRIDAY NIGHT-SATURDAY NIGHT...EXPECT PRECIP CHANCES TO BE MAXIMIZED
RIGHT AROUND SUNSET ON FRIDAY NIGHT BEFORE PRECIP CHANCES BEGIN TO
END FROM SOUTHWEST TO NORTHEAST AS DOWNWARD MOTION INTENSIFIES
BEHIND DEPARTING TROUGH. AM A LITTLE CONCERNED ABOUT POTENTIAL FOR
ACCUMULATING SNOW ACROSS NORTHWEST CWA WITH POTENTIAL INSTABILITY
PRESENT AND PERSISTENT...NEARLY STATIONARY AREA OF LOW LEVEL
FRONTOGENESIS. HOWEVER...THIS AREA WOULD BE ONE OF THE FIRST AREAS
FOR FORCING TO DIMINISH AS UPPER LEVEL FLOW BECOMES SUBSIDENT AND
AFTER LOOKING AT PAST FEW ROUNDS OF ANALOG GUIDANCE...DO NOT THINK
PROBABILITY FOR MEANINGFUL SNOWFALL ACCUMULATIONS IS ALL THAT HIGH.
WINDS WILL LIKELY PICK UP INTO THE 20-30 MPH RANGE AS SYSTEM
DEPARTS...BUT EXPECT ANY POTENTIAL SNOW TO BE OVER WITH BEFORE WINDS
DEVELOP.
ON SATURDAY...STRONG DOWNWARD MOTION WILL BRING AN END TO THE
PRECIPITATION THREAT AND BRING SOME CLEARING TO THE AREA IN THE
MORNING...WITH CLOUDS BEGINNING TO INCREASE LATE IN THE AFTERNOON AS
A WEAK SHORT WAVE TROUGH APPROACHES. WHILE MODELS/ENSEMBLES
GENERALLY SUPPORT A PRECIPITATION THREAT...HAVE CONCERNS THAT A LOW
AMPLITUDE/TRANSIENT DISTURBANCE WILL PROVIDE ENOUGH FORCED ASCENT TO
SATURATE DRY LOWER LEVELS LEFT IN WAKE OF PREVIOUS SYSTEM AND WILL
KEEP POPS LIMITED TO 10-20 FOR THE EVENING PERIOD.
SUNDAY THROUGH WEDNESDAY...DETERMINISTIC AND ENSEMBLE OUTPUT
CONTINUE TO SHOW A LOT OF SPREAD THROUGH THE ENTIRE PERIOD.
HOWEVER...IN GENERAL THEY ARE SHOWING A FAST FLOW WITH MULTIPLE
EMBEDDED SHORTWAVE TROUGHS MOVING THROUGH THIS FLOW. FOR THE AREA
THIS IS NOT A FAVORABLE FLOW FOR PULLING IN SIGNIFICANT MOISTURE FOR
THESE SYSTEMS TO WORK WITH. BASED ON THAT...MODEL TRENDS IN THE LAST
24 HOURS...AND COLLABORATION...REMOVED WHAT WAS LEFT OF THE CHANCE
OF PRECIPITATION THAT THE CRH INIT GAVE ME FOR MONDAY. SO IT IS NOW DRY
THROUGH THIS PERIOD. OTHER THAN THAT...SAW NO NEED TO MAKE ANY
CHANGES TO THE GUIDANCE GIVEN TO ME.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1043 AM MST THU DEC 13 2012
VFR CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THE PREVAILING TAF
PERIOD. WINDS WILL REMAIN LIGHT AND VARIABLE AT BOTH TERMINALS
THROUGH TOMORROW MORNING BEFORE BECOMING PREDOMINATELY SOUTHERLY
AHEAD OF AN INCOMING STORM SYSTEM. CLOUD COVER WILL INCREASE AND
CIGS WILL BEGIN TO LOWER LATE IN THE PERIOD AS THIS SYSTEM APPROACHES
THE REGION.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JRM
LONG TERM...JRM/BULLER
AVIATION...PMM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
418 AM MST THU DEC 13 2012
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 158 AM MST THU DEC 13 2012
04Z WATER VAPOR IMAGERY AND RAP ANALYSIS INDICATED LOW AMPLITUDE H5
RIDGE IN PLACE ACROSS THE REGION WITH STRONG TROUGH ALONG AND JUST
OF THE WEST COAST. THIS SYSTEM WILL PLAY A LARGE ROLE ON EXPECTED
WEATHER THROUGH THE START OF THE WEEKEND...AND IS STILL NOT TOTALLY
BEING SAMPLED BY UPPER AIR NETWORK. 00Z SOUNDINGS INDICATED A DRY
AND MUCH WARMER AIRMASS THAN 24 HOURS AGO...WITH STRONGEST WARMING
BETWEEN H8 AND H6. AT THE SFC...TROUGH AXIS WAS IN PLACE ALONG
ROUGHLY A KLBF TO KTRB LINE.
MAIN FORECAST CONCERNS WILL BE SKY COVER THIS MORNING AND TONIGHT
DUE TO GEMINID METEOR SHOWER AND PRECIPITATION POTENTIAL FRIDAY.
TODAY-TONIGHT...SHORT WAVE RIDGING WILL CONTINUE ACROSS THE AREA
THROUGH THE EVENING AND ALTHOUGH WEAK AMPLITUDE WILL NOT CREATE ANY
STRONG SUBSIDENCE DRY AND STABLE CONDITIONS EXPECTED SO ANY WEAK
ASCENT WILL NOT HAVE MUCH OF AN IMPACT ON SENSIBLE WEATHER. ALREADY
SEEING A LOT OF CIRRUS MOVING OVER THE AREA...WITH 80-90KT H3 WINDS
HELPING INDUCE CIRRUS DOWNSTREAM OF THE MOUNTAINS. GIVEN EXPECTED
FLOW ALOFT...EXPECT CLOUD COVER TO PERSIST THROUGH THE MORNING HOURS
WHICH WILL LIKELY INHIBIT THE VIEWING OF METEOR SHOWER IN SOME
LOCATIONS. SKIES WILL CLEAR DURING THE AFTERNOON AS FLOW ALOFT
BECOMES LESS PERPENDICULAR TO MOUNTAINS AND RRQ OF H3 JET STREAK
SHIFT TO THE NORTH AND EAST ACROSS SOUTH DAKOTA. WHILE CIRRUS WILL
LINGER ACROSS NORTHERN CWA TONIGHT...SHOULD BE A FEW PERIODS WHERE
CLOUDS CLEAR UP ALTHOUGH CLOUD COVER WILL BEGIN TO INCREASE RAPIDLY
FROM THE SOUTHWEST AFTER 2 AM MST (3 AM CST) AS NEXT SYSTEM
APPROACHES.
FRIDAY...MUCH MORE ACTIVE WEATHER IS EXPECTED ACROSS THE CWA ON
FRIDAY AS STRONG TROUGH BEGINS TO MOVE OVER THE AREA. MODELS HAVE
COME INTO MUCH BETTER AGREEMENT WITH TIMING OF FAIRLY PROGRESSIVE
TROUGH ACROSS THE PLAINS...ALTHOUGH LOOKING AT THE INDIVIDUAL
DYNAMIC TROP ANALYSIS FROM THE GFS AND NAM...AM A LITTLE CONCERNED
WITH GFS DEPICTING A MUCH LESS CONSOLIDATED PV ANOMALY WHICH OFTEN
TENDS TO HINDER WIDESPREAD PERSISTENT PRECIPITATION RATHER THAN HELP.
WHILE THE POSSIBILITY OF TROUGH COMING OUT IN PIECES LOWERS
CONFIDENCE SOMEWHAT...ENOUGH AGREEMENT BETWEEN OPERATIONAL MODELS TO
SUPPORT PROBABLY ONE OF THE BETTER CHANCES FOR PRECIP OVER THE PAST
MONTH AND BASED ON ALL FACTORS THINK 30-60 PROBABILITIES WARRANTED.
BEST CHANCES WILL BE ACROSS EASTERN CWA WHERE ISENTROPIC ANALYSIS
INDICATES STRONGEST MOISTURE TRANSPORT IN THIS AREA WITH A SECOND
MAXIMUM IN FORCING LOCATED TO NORTH OF SFC WARM FRONT IN NORTHWEST
CWA. DEPENDING ON HOW QUICKLY CLEARING OCCURS ONCE DRY SLOT
CIRCULATION BEGINS TO ENTER CWA COULD POSSIBLY SEE A SFC BASED
THUNDERSTORM ALONG DRY LINE IN SOUTHEASTERN ZONES AROUND SUNSET.
WHILE THERE IS SOME DATA SUGGESTING A CHANGE OVER TO SNOW IS
POSSIBLE IN THE WEST DURING THE AFTERNOON...AM GOING TO LEAN TOWARDS
A CONSENSUS OF AVAILABLE DATA AND HOLD OFF ON ANY COMPLETE CHANGE
OVER UNTIL AFTER 00Z.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 158 AM MST THU DEC 13 2012
FRIDAY NIGHT-SATURDAY NIGHT...EXPECT PRECIP CHANCES TO BE MAXIMIZED
RIGHT AROUND SUNSET ON FRIDAY NIGHT BEFORE PRECIP CHANCES BEGIN TO
END FROM SOUTHWEST TO NORTHEAST AS DOWNWARD MOTION INTENSIFIES
BEHIND DEPARTING TROUGH. AM A LITTLE CONCERNED ABOUT POTENTIAL FOR
ACCUMULATING SNOW ACROSS NORTHWEST CWA WITH POTENTIAL INSTABILITY
PRESENT AND PERSISTENT...NEARLY STATIONARY AREA OF LOW LEVEL
FRONTOGENESIS. HOWEVER...THIS AREA WOULD BE ONE OF THE FIRST AREAS
FOR FORCING TO DIMINISH AS UPPER LEVEL FLOW BECOMES SUBSIDENT AND
AFTER LOOKING AT PAST FEW ROUNDS OF ANALOG GUIDANCE...DO NOT THINK
PROBABILITY FOR MEANINGFUL SNOWFALL ACCUMULATIONS IS ALL THAT HIGH.
WINDS WILL LIKELY PICK UP INTO THE 20-30 MPH RANGE AS SYSTEM
DEPARTS...BUT EXPECT ANY POTENTIAL SNOW TO BE OVER WITH BEFORE WINDS
DEVELOP.
ON SATURDAY...STRONG DOWNWARD MOTION WILL BRING AN END TO THE
PRECIPITATION THREAT AND BRING SOME CLEARING TO THE AREA IN THE
MORNING...WITH CLOUDS BEGINNING TO INCREASE LATE IN THE AFTERNOON AS
A WEAK SHORT WAVE TROUGH APPROACHES. WHILE MODELS/ENSEMBLES
GENERALLY SUPPORT A PRECIPITATION THREAT...HAVE CONCERNS THAT A LOW
AMPLITUDE/TRANSIENT DISTURBANCE WILL PROVIDE ENOUGH FORCED ASCENT TO
SATURATE DRY LOWER LEVELS LEFT IN WAKE OF PREVIOUS SYSTEM AND WILL
KEEP POPS LIMITED TO 10-20 FOR THE EVENING PERIOD.
SUNDAY THROUGH WEDNESDAY...DETERMINISTIC AND ENSEMBLE OUTPUT
CONTINUE TO SHOW A LOT OF SPREAD THROUGH THE ENTIRE PERIOD.
HOWEVER...IN GENERAL THEY ARE SHOWING A FAST FLOW WITH MULTIPLE
EMBEDDED SHORTWAVE TROUGHS MOVING THROUGH THIS FLOW. FOR THE AREA
THIS IS NOT A FAVORABLE FLOW FOR PULLING IN SIGNIFICANT MOISTURE FOR
THESE SYSTEMS TO WORK WITH. BASED ON THAT...MODEL TRENDS IN THE LAST
24 HOURS...AND COLLABORATION...REMOVED WHAT WAS LEFT OF THE CHANCE
OF PRECIPITATION THAT THE CRH INIT GAVE ME FOR MONDAY. SO IT IS NOW DRY
THROUGH THIS PERIOD. OTHER THAN THAT...SAW NO NEED TO MAKE ANY
CHANGES TO THE GUIDANCE GIVEN TO ME.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 417 AM MST THU DEC 13 2012
VFR CONDITIONS EXPECTED THROUGH 12Z FRIDAY WITH LIGHT WINDS
GRADUALLY BECOMING SOUTHEAST THROUGH THE DAY.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JRM
LONG TERM...JRM/BULLER
AVIATION...JRM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
201 AM MST THU DEC 13 2012
.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 158 AM MST THU DEC 13 2012
04Z WATER VAPOR IMAGERY AND RAP ANALYSIS INDICATED LOW AMPLITUDE H5
RIDGE IN PLACE ACROSS THE REGION WITH STRONG TROUGH ALONG AND JUST
OF THE WEST COAST. THIS SYSTEM WILL PLAY A LARGE ROLE ON EXPECTED
WEATHER THROUGH THE START OF THE WEEKEND...AND IS STILL NOT TOTALLY
BEING SAMPLED BY UPPER AIR NETWORK. 00Z SOUNDINGS INDICATED A DRY
AND MUCH WARMER AIRMASS THAN 24 HOURS AGO...WITH STRONGEST WARMING
BETWEEN H8 AND H6. AT THE SFC...TROUGH AXIS WAS IN PLACE ALONG
ROUGHLY A KLBF TO KTRB LINE.
MAIN FORECAST CONCERNS WILL BE SKY COVER THIS MORNING AND TONIGHT
DUE TO GEMINID METEOR SHOWER AND PRECIPITATION POTENTIAL FRIDAY.
TODAY-TONIGHT...SHORT WAVE RIDGING WILL CONTINUE ACROSS THE AREA
THROUGH THE EVENING AND ALTHOUGH WEAK AMPLITUDE WILL NOT CREATE ANY
STRONG SUBSIDENCE DRY AND STABLE CONDITIONS EXPECTED SO ANY WEAK
ASCENT WILL NOT HAVE MUCH OF AN IMPACT ON SENSIBLE WEATHER. ALREADY
SEEING A LOT OF CIRRUS MOVING OVER THE AREA...WITH 80-90KT H3 WINDS
HELPING INDUCE CIRRUS DOWNSTREAM OF THE MOUNTAINS. GIVEN EXPECTED
FLOW ALOFT...EXPECT CLOUD COVER TO PERSIST THROUGH THE MORNING HOURS
WHICH WILL LIKELY INHIBIT THE VIEWING OF METEOR SHOWER IN SOME
LOCATIONS. SKIES WILL CLEAR DURING THE AFTERNOON AS FLOW ALOFT
BECOMES LESS PERPENDICULAR TO MOUNTAINS AND RRQ OF H3 JET STREAK
SHIFT TO THE NORTH AND EAST ACROSS SOUTH DAKOTA. WHILE CIRRUS WILL
LINGER ACROSS NORTHERN CWA TONIGHT...SHOULD BE A FEW PERIODS WHERE
CLOUDS CLEAR UP ALTHOUGH CLOUD COVER WILL BEGIN TO INCREASE RAPIDLY
FROM THE SOUTHWEST AFTER 2 AM MST (3 AM CST) AS NEXT SYSTEM
APPROACHES.
FRIDAY...MUCH MORE ACTIVE WEATHER IS EXPECTED ACROSS THE CWA ON
FRIDAY AS STRONG TROUGH BEGINS TO MOVE OVER THE AREA. MODELS HAVE
COME INTO MUCH BETTER AGREEMENT WITH TIMING OF FAIRLY PROGRESSIVE
TROUGH ACROSS THE PLAINS...ALTHOUGH LOOKING AT THE INDIVIDUAL
DYNAMIC TROP ANALYSIS FROM THE GFS AND NAM...AM A LITTLE CONCERNED
WITH GFS DEPICTING A MUCH LESS CONSOLIDATED PV ANOMALY WHICH OFTEN
TENDS TO HINDER WIDESPREAD PERSISTENT PRECIPITATION RATHER THAN HELP.
WHILE THE POSSIBILITY OF TROUGH COMING OUT IN PIECES LOWERS
CONFIDENCE SOMEWHAT...ENOUGH AGREEMENT BETWEEN OPERATIONAL MODELS TO
SUPPORT PROBABLY ONE OF THE BETTER CHANCES FOR PRECIP OVER THE PAST
MONTH AND BASED ON ALL FACTORS THINK 30-60 PROBABILITIES WARRANTED.
BEST CHANCES WILL BE ACROSS EASTERN CWA WHERE ISENTROPIC ANALYSIS
INDICATES STRONGEST MOISTURE TRANSPORT IN THIS AREA WITH A SECOND
MAXIMUM IN FORCING LOCATED TO NORTH OF SFC WARM FRONT IN NORTHWEST
CWA. DEPENDING ON HOW QUICKLY CLEARING OCCURS ONCE DRY SLOT
CIRCULATION BEGINS TO ENTER CWA COULD POSSIBLY SEE A SFC BASED
THUNDERSTORM ALONG DRY LINE IN SOUTHEASTERN ZONES AROUND SUNSET.
WHILE THERE IS SOME DATA SUGGESTING A CHANGE OVER TO SNOW IS
POSSIBLE IN THE WEST DURING THE AFTERNOON...AM GOING TO LEAN TOWARDS
A CONSENSUS OF AVAILABLE DATA AND HOLD OFF ON ANY COMPLETE CHANGE
OVER UNTIL AFTER 00Z.
.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 158 AM MST THU DEC 13 2012
FRIDAY NIGHT-SATURDAY NIGHT...EXPECT PRECIP CHANCES TO BE MAXIMIZED
RIGHT AROUND SUNSET ON FRIDAY NIGHT BEFORE PRECIP CHANCES BEGIN TO
END FROM SOUTHWEST TO NORTHEAST AS DOWNWARD MOTION INTENSIFIES
BEHIND DEPARTING TROUGH. AM A LITTLE CONCERNED ABOUT POTENTIAL FOR
ACCUMULATING SNOW ACROSS NORTHWEST CWA WITH POTENTIAL INSTABILITY
PRESENT AND PERSISTENT...NEARLY STATIONARY AREA OF LOW LEVEL
FRONTOGENESIS. HOWEVER...THIS AREA WOULD BE ONE OF THE FIRST AREAS
FOR FORCING TO DIMINISH AS UPPER LEVEL FLOW BECOMES SUBSIDENT AND
AFTER LOOKING AT PAST FEW ROUNDS OF ANALOG GUIDANCE...DO NOT THINK
PROBABILITY FOR MEANINGFUL SNOWFALL ACCUMULATIONS IS ALL THAT HIGH.
WINDS WILL LIKELY PICK UP INTO THE 20-30 MPH RANGE AS SYSTEM
DEPARTS...BUT EXPECT ANY POTENTIAL SNOW TO BE OVER WITH BEFORE WINDS
DEVELOP.
ON SATURDAY...STRONG DOWNWARD MOTION WILL BRING AN END TO THE
PRECIPITATION THREAT AND BRING SOME CLEARING TO THE AREA IN THE
MORNING...WITH CLOUDS BEGINNING TO INCREASE LATE IN THE AFTERNOON AS
A WEAK SHORT WAVE TROUGH APPROACHES. WHILE MODELS/ENSEMBLES
GENERALLY SUPPORT A PRECIPITATION THREAT...HAVE CONCERNS THAT A LOW
AMPLITUDE/TRANSIENT DISTURBANCE WILL PROVIDE ENOUGH FORCED ASCENT TO
SATURATE DRY LOWER LEVELS LEFT IN WAKE OF PREVIOUS SYSTEM AND WILL
KEEP POPS LIMITED TO 10-20 FOR THE EVENING PERIOD.
SUNDAY THROUGH WEDNESDAY...DETERMINISTIC AND ENSEMBLE OUTPUT
CONTINUE TO SHOW A LOT OF SPREAD THROUGH THE ENTIRE PERIOD.
HOWEVER...IN GENERAL THEY ARE SHOWING A FAST FLOW WITH MULTIPLE
EMBEDDED SHORTWAVE TROUGHS MOVING THROUGH THIS FLOW. FOR THE AREA
THIS IS NOT A FAVORABLE FLOW FOR PULLING IN SIGNIFICANT MOISTURE FOR
THESE SYSTEMS TO WORK WITH. BASED ON THAT...MODEL TRENDS IN THE LAST
24 HOURS...AND COLLABORATION...REMOVED WHAT WAS LEFT OF THE CHANCE
OF PRECIPITATION THAT THE CRH INIT GAVE ME FOR MONDAY. SO IT IS NOW DRY
THROUGH THIS PERIOD. OTHER THAN THAT...SAW NO NEED TO MAKE ANY
CHANGES TO THE GUIDANCE GIVEN TO ME.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1000 PM MST WED DEC 12 2012
VFR THROUGH THE PERIOD AT KGLD AND KMCK. SFC TROUGH TO MOVE
THROUGH IN THE NEXT FEW HOURS WITH W/NW AT 5-10KTS. WINDS BECOME
SOUTHEASTERLY BY 18Z-19Z THURSDAY MORNING AT 5-10KTS AHEAD OF A
SFC LOW EXPECTED TO BE IN SOUTHEAST COLORADO. ONLY HIGH LEVEL
CLOUDINESS EXPECTED...MAINLY THROUGH THE MORNING HOURS BEFORE
LIFTING NORTH OF THE AREA. ANOTHER BATCH MAY DEVELOP ALONG THE
FRONT RANGE THURSDAY AFTERNOON BRINGING ANOTHER INCREASE OVER OUR
TERMINALS DURING THAT PERIOD.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
CO...NONE.
NE...NONE.
&&
$$
SHORT TERM...JRM
LONG TERM...JRM/BULLER
AVIATION...99
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1251 PM EST THU DEC 13 2012
.SYNOPSIS...
ISSUED AT 348 AM EST THU DEC 13 2012
A BROAD AREA OF HIGH PRESSURE OVER THE EAST COAST OF THE U. S. WILL
BRING QUIET...WARM WEATHER TO NORTHERN MICHIGAN THROUGH FRIDAY. LOW
PRESSURE WILL MOVE INTO THE WESTERN GREAT LAKES THIS WEEKEND AND
GENERATE RAIN OR SNOW OVER NORTHERN MICHIGAN SATURDAY AND SUNDAY.
COLDER AIR AND SNOW SHOWERS WILL SETTLE INTO THE GREAT LAKES TO
BEGIN THE UPCOMING WORK WEEK.
&&
.UPDATE...
ISSUED AT 1246 PM EST THU DEC 13 2012
NO NOTEWORTHY CHANGES NEEDED AS ABOVE NORMAL WARMTH VIA GUSTY
SOUTHWEST WINDS CONTINUE.
UPDATE ISSUED AT 943 AM EST THU DEC 13 2012
INCREASINGLY GUSTY SOUTHWEST FLOW ON BACKSIDE OF NEW ENGLAND
CENTERED HIGH PRESSURE ONCE AGAIN SPREADING ABOVE NORMAL WARMTH
ACROSS THE NORTH WOODS...WITH MID MORNING READINGS ALREADY PUSHING
40 DEGREES ALONG THE LAKE MICHIGAN SHORELINE. THESE TRENDS SHOULD
CONTINUE...WITH MAINTENANCE OF GUSTY SOUTHWEST WINDS RESULTING IN
AFTERNOON HIGHS MAKING A RUN INTO THE LOWER AND MIDDLE 40S. DESPITE
JUST OFF THE DECK LOW LEVEL WIND MAX...UPWARDS OF 40 KNOTS AT H925
PER LATEST HIGH RES RAP GUIDANCE...SHALLOW MIXING PREVENTING FULL
WIND POTENTIAL FROM REACHING THE SURFACE...SAFELY PUTTING WIND GUSTS
BELOW ADVISORY CRITERIA. STILL NO DOUBT A WINDY ONE...WITH GUSTS
THIS AFTERNOON LIKELY TOPPING 30 MPH. STILL A PLETHORA OF MID AND
UPPER LEVEL CLOUDS...ESPECIALLY ACROSS THE NORTH HALF OF THE
AREA...AHEAD OF LOW AMPLITUDE WAVE PIVOTING EAST ACROSS NORTHWEST
WISCONSIN/WESTERN LAKE SUPERIOR. SOME LIGHT RETURNS NOTED OVER
EASTERN UPPER MICHIGAN THIS MORNING FALLING FROM 11KFT CLOUD
DECK...ALTHOUGH DEARTH OF SUB H70 MOISTURE (SEE LOCAL 12Z SOUNDING)
PREVENTING ANYTHING FROM REACHING THE SURFACE. SOMEWHAT DEEPER
MOISTURE/FGEN DYNAMICS ASSOCIATED BACK CLOSER TO THE WAVE...WHERE
SOME LIGHT SNOW IS REACHING THE SURFACE. DEEPEST MOISTURE AND FGEN
DYNAMICS LOOK TO SLIDE ACROSS LAKE SUPERIOR THIS AFTERNOON...KEEPING
MOST...IF NOT ALL...RAIN/SNOW NORTH OF EASTERN UPPER. MAY YET SEE A
FEW SPRINKLES/FLURRIES...AND WILL SIMPLY RIDE WITH THIS GOING
INHERITED THEME.
UPDATE ISSUED AT 635 AM EST THU DEC 13 2012
FRESHENED UP SKY COVER GRIDS BASED ON SATELLITE TRENDS...OTHERWISE
NO MAJOR FORECAST CHANGES.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 348 AM EST THU DEC 13 2012
EARLY MORNING SURFACE ANALYSIS FINDS A WAVY FRONTAL BOUNDARY THAT
EXTENDS FROM NORTHWEST QUEBEC...BACK ACROSS NORTHERN ONTARIO TO A
FRONTAL WAVE OVER NORTHEAST MINNESOTA. ANOTHER QUASI-WARM FRONT RAN
NORTHWEST-SOUTHEAST FROM EASTERN LAKE SUPERIOR INTO THE LOWER GREAT
LAKES/NORTHERN NEW YORK. TIGHT GRADIENT BETWEEN THE MINNESOTA LOW
AND A 1031MB HIGH OVER WESTERN PENNSYLVANIA FUNNELING INCREASING
SOUTHERLY WINDS INTO MICHIGAN EARLY THIS MORNING. MAIN CENTERS OF
ACTION ALOFT ARE A DIGGING TROUGH INTO SOUTHERN CALIFORNIA...AND
ANOTHER SHORT WAVE TROUGH LIFTING OUT OVER THE SOUTHEASTERN U.S..
WATER VAPOR IMAGERY ALSO REVEALS A SMALL VORTICITY CENTER OVER THE
DAKOTAS ASSOCIATED WITH A 60KT MID LEVEL JET STREAK. WARM ADVECTION
HAS DRAGGED MID/HIGH CLOUDS ACROSS THE FORECAST AREA EARLY THIS
MORNING...WITH RADAR RETURNS ACROSS NORTHERN MICHIGAN EXTENDING BACK
ACROSS THE UPPER PENINSULA. BUT DRY AIR BELOW 725MB PER 00Z APX/GRB
SOUNDINGS PRECLUDING MUCH IN THE WAY OF SURFACE PRECIPITATION
REPORTS (SOME LIGHT PRECIP AT ERY/YAM).
SURFACE WAVE OVER MINNESOTA EXPECTED TO HEAD EAST-NORTHEAST TODAY
TOWARD WEAK PRESSURE FALL CENTER NORTH OF LAKE SUPERIOR. ASSOCIATED
FRONTAL BOUNDARY WILL GET STRETCHED IN A NORTHEAST-SOUTHWEST
FASHION ACROSS THE UPPER MIDWEST AND THE UPPER PENINSULA...WITH THE
BOUNDARY EXPECTED TO DROOP INTO THE STRAITS REGION OVERNIGHT. SHEAR
VORTICITY CENTER OVER THE DAKOTAS WILL EVENTUALLY SLIDE ACROSS
NORTHERN MICHIGAN THIS AFTERNOON. BUT OVERALL FORECAST CONCERNS ARE
MINIMAL...MAINLY DEALING WITH TEMPERATURES/WINDS TODAY...AND
TEMPERATURES TONIGHT WITH THE SAGGING COLD FRONT.
NORTH-SOUTH "GRADIENT" IN CLOUD COVER EXPECTED TODAY WITH SATELLITE
TRENDS SUPPORTING THE IDEA OF THICKER MID CLOUDS REMAINING ACROSS
UPPER MICHIGAN TODAY...AIDED BY ARRIVAL OF ABOVE MENTIONED SHORT
WAVE/SHEAR VORTICITY CENTER...WHILE CLOUD COVER THINS OUT FROM NORTH
TO SOUTH ACROSS THE LOWER PENINSULA. 00Z 850MB ANALYSIS SHOWS AN
AREA OF HIGHER DEW POINTS ACROSS EASTERN SOUTH DAKOTA/NORTHERN
MINNESOTA THAT GETS PULLED EAST ACROSS THE UPPER PENINSULA...AND
WITH THE ARRIVAL OF ADDITIONAL FORCING LATER TODAY QUESTION IS THERE
WHERE DRY LAYER CAN BE ERODED SUFFICIENTLY TO ALLOW FOR SOME LIGHT
PRECIPITATION. PROBABLY NOT WORTH A MEASURABLE POP MENTION OUTSIDE
OF MAYBE WHITEFISH BAY AND POINTS NORTH. WINDS ARE GOING TO BE
ANOTHER CONCERN...WITH FORECAST SOUNDINGS SHOWING TYPICAL INABILITY
TO DEPICT MIXING OVER SNOW COVER. A 30-40KT SOUTHWESTERLY LOW LEVEL
JET RIGHT OFF THE DECK (3K FEET AGL WIND OFF KAPX VWP ALREADY
35-40KT) WON`T REQUIRE MUCH MIXING TO PULL STRONGER GUSTS DOWN TO
THE SURFACE (EVIDENT IN 35KT GUST IN ERY 0735Z OB...THOUGH POSSIBLY
AIDED BY EVAPORATIVE COOLING WITH SOME LIGHT RAIN AT THE TIME).
ANTICIPATE WIND GUSTS OF 30-40 MPH ACROSS NORTHERN LOWER THIS
AFTERNOON...DIMINISHING TOWARD EVENING. TEMPERATURES ALREADY ON THE
WAY UP THIS MORNING...WITH WIDESPREAD MID/UPPER 30S WITH A FEW 40
DEGREE READINGS. A MILD START COMBINED WITH GOOD MECHANICAL MIXING
SHOULD PUSH TEMPERATURES WELL INTO THE 40S THIS AFTERNOON...A GOOD
10-15 DEGREES ABOVE MID DECEMBER NORMALS.
STRETCHED OUT COLD FRONT GRADUALLY SINKS INTO UPPER MICHIGAN AND THE
STRAITS REGION OVERNIGHT. GOOD DEAL OF POST-FRONTAL LOW CLOUD
ALREADY IN PLACE...AND COMBINED WITH LOW LEVEL COLD ADVECTION
LEADING TO SHALLOW INSTABILITY DEVELOPING OVER LAKE SUPERIOR AND FAR
NORTHERN LAKE MICHIGAN...EXPECT SKIES TO REMAIN ON THE CLOUDY SIDE
ACROSS UPPER MICHIGAN TONIGHT...WITH CLOUDS SPILLING INTO NORTHERN
LOWER MICHIGAN OVERNIGHT WITH THE FRONT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 348 AM EST THU DEC 13 2012
FRIDAY...500 MB HEIGHTS RISE AND THE 850 MB TEMPERATURES REMAIN
AROUND 0C IN N LOWER. 850 MB RH IS AROUND 50% AND WITH THE
MID-LEVELS (700-500 MB) STILL PRETTY DRY. THIS WILL LEAVE THE REGION
DRY.
FRIDAY NIGHT...THE MOISTURE FROM THE NEXT SYSTEM MOVES INTO THE
REGION AND CLOUDS WILL INCREASE. LOOKS LIKE WITH THE 500 MB RIDGE
OVER US THAT THE RAIN/SNOW WILL BE HELD OFF UNTIL THE DAY ON
SATURDAY.
SATURDAY...AS THE LOW MOVES OUT OF THE CENTRAL PLAINS, THE MOISTURE
MOVES ACROSS THE REGION. BOTH MODELS START OUT WITH 850 MB
TEMPERATURES OVER NW LOWER WARM ENOUGH TO PRODUCE SNOW/RAIN/FREEZING
RAIN IN THE MORNING. HOWEVER, BY THE AFTERNOON, IT LOOKS LIKE A
SNOW/RAIN MIX ON THE ECMWF AS THE BELOW 0C AIR AT 850 MB HAS DROPPED
SOUTH INTO S LOWER. THIS SEEMS TO BE FROM EVAP COOLING. THE ECMWF
SOUNDINGS FOR 12Z SHOWED A LAYER OF DRY AIR OVER THE FORECAST AREA,
THAT WOULD ALLOW THE COOLING AT 850 MB. THE GFS SHOWS THE MOISTURE
MOVING IN RAPIDLY AND ALLOWING THE WARMER AIR CONTINUE SO THAT IT IS
ONLY RAIN IN THE SOUTHERN COUNTIES OF THE FORECAST AREA. SO LOOKS
LIKE THERE IS A CHANCE FOR RAIN OR SNOW OR SOME KIND OF MIX.
OVERNIGHT, THE MODELS CONTINUE THE TOSS UP, HOWEVER, IT DOES LOOK
LIKE E UPPER SHOULD BE COLD ENOUGH FOR A SNOW ONLY FORECAST FROM THE
OUTSET. HOWEVER, THE AMOUNTS SHOULD BE MINOR TO LIGHT AS E UPPER
REMAINS A GOOD DISTANCE FROM THE MAIN FORCING. OVERNIGHT, THE WARMER
AIR MOVES INTO AN AREA SOUTH AND EAST OF A LINE FROM APN TO MBL. SO
WILL HAVE RAIN LIKELY, AND A RAIN/SNOW MIX NORTH AND WEST TO THE
STRAITS, NORTH OF WHICH WILL BE ALL SNOW. AFTER THE ECMWF MADE ITS
COURSE CORRECTION A COUPLE OF DAYS AGO, IT LOOKED LIKE IT WAS
HOLDING PRETTY CONSISTENT ON THE TRACK OF THE LOW ALONG I-96.
HOWEVER, WITH THE 00Z, THE ECMWF HAS INTRODUCED WARM AIR AT 850 MB
FARTHER NORTH IN N LOWER, SO THAT NOW SATURDAY NIGHT LOOKS LIKE RAIN
UP TO M-72 AND RAIN OR SNOW NORTH.
EXTENDED (SUNDAY THROUGH WEDNESDAY)...SUNDAY, AND THIS WARM TRACK
FOR THE ECMWF CONTINUES ON INTO THE DAY AND NOT UNTIL THE SFC LOW
MOVES EAST OF THE REGION WILL THE COLD AIR MOVE BACK INTO THE REGION
AND SNOW BECOMES DOMINATE AGAIN AND THAT DOESN`T LOOK LIKELY UNTIL
SUNDAY NIGHT. CONSIDERING THE LIKELIHOOD OF THE EAST COASTAL SYSTEM
BEGINNING TO DEVELOP, NOT SURE WHICH MODEL HAS THE UPPER HAND.
MONDAY, NE TO N FLOW WITH THE 850 MB TEMPERATURES IN N LAKE MICHIGAN
AROUND -6C PUTS US AROUND 13-14C DELTA T. SO MARGINAL DELTA T AND NE
FLOW DOESN`T DO MUCH LES IN NW LOWER. IN NE LOWER, THE 850 MB
TEMPERATURES ARE WARMER, SO UNLIKELY THERE WILL BE MUCH IN THE WAY
OF ENHANCEMENT. TEMPERATURE CONTINUE TO COOL AND THE WINDS GO NNW
OVERNIGHT, SO HAVE INCREASED THE POPS TO ALLOW SOME CHANCE POPS IN
THE NNW FLOW AREAS. TUESDAY, THE REAL COLD AIR WITH THIS SYSTEM
STAYS BOTTLED UP UNTIL TUESDAY MORNING WITH THE SYSTEM MOVING UP THE
EAST COAST AND THE WINDS OUT OF THE NW OVER THE FORECAST AREA. SO
BUMPED UP THE POPS FOR LOW CHANCE SNOW FROM LES. WEDNESDAY, THE 500
MB RIDGE MOVE THROUGH THE REGION AND THE WINDS REVERSE OUT OF THE SE
AGAIN. THIS BRINGS WARM AIR NORTH AHEAD OF THE NEXT FRONT. THE GFS
HAS SOME SNOW, AND THE ECMWF IS DRY, SO LOW CHANCE POPS FOR SNOW FOR
NOW.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1246 PM EST THU DEC 13 2012
GUSTY SOUTHWEST WINDS EXPECTED FOR THE REMAINDER OF THIS AFTERNOON
WELL AHEAD OF A DECAYING COLD FRONT DROPPING IN FROM THE NORTHWEST
LAKES. LOW LEVEL MOISTURE WILL DEEPEN TONIGHT...AND COMBINED WITH
PASSING FRONTAL FEATURE AND QUICKLY SUBSIDING WINDS...WILL LIKELY
KICK OFF AN EXPANDING AREA OF MVFR STRATUS...WITH EVEN SOME FOG
POTENTIAL (ALTHOUGH FOG POTENTIAL IS GREATEST OVER THE INTERIOR
HIGHLANDS). WILL NEED TO MONITOR CLOSELY...AS POTENTIAL FOR IFR
OVERCAST EXISTS AND FOG MAY BECOME MORE EXTENSIVE THAN CURRENTLY
FORECAST. SLOW IMPROVEMENT FRIDAY IN LIGHT WIND REGIME.
&&
.MARINE...
ISSUED AT 348 AM EST THU DEC 13 2012
GUSTY SOUTH/SOUTHWEST WINDS THIS MORNING...WITH SOME MARGINAL GALE
FORCE GUSTS ON NORTHERN LAKE MICHIGAN. WILL KEEP GALE WARNINGS FOR
THIS MORNING ON NORTHERN LAKE MICHIGAN...WHICH WILL NEED TO
TRANSITION OF SMALL CRAFT ADVISORIES FOR AT LEAST THIS AFTERNOON IF
NOT INTO TONIGHT DUE TO CHOPPY SEAS. ALSO ANTICIPATE SMALL CRAFT
ADVISORIES FOR REMAINING NEARSHORE ZONES THROUGH TODAY WITH THE
POSSIBLE EXCEPTION OF WHITEFISH BAY. WIND SPEEDS WILL DROP THIS
EVENING AND WINDS WILL VEER TO A MORE WEST OR NORTHWEST DIRECTION AS
A COLD FRONT SAGS ACROSS THE UPPER PENINSULA.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
LHZ345>349.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR LMZ323-
341-342-344>346.
LS...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR LSZ322.
&&
$$
UPDATE...MB
SYNOPSIS...JSL
SHORT TERM...JPB
LONG TERM...JSL
AVIATION...MB
MARINE...JPB
AREA FORECAST DISCUSSION
NWS GAYLORD MI
944 AM EST THU DEC 13 2012
.SYNOPSIS...
ISSUED AT 348 AM EST THU DEC 13 2012
A BROAD AREA OF HIGH PRESSURE OVER THE EAST COAST OF THE U. S. WILL
BRING QUIET...WARM WEATHER TO NORTHERN MICHIGAN THROUGH FRIDAY. LOW
PRESSURE WILL MOVE INTO THE WESTERN GREAT LAKES THIS WEEKEND AND
GENERATE RAIN OR SNOW OVER NORTHERN MICHIGAN SATURDAY AND SUNDAY.
COLDER AIR AND SNOW SHOWERS WILL SETTLE INTO THE GREAT LAKES TO
BEGIN THE UPCOMING WORK WEEK.
&&
.UPDATE...
ISSUED AT 943 AM EST THU DEC 13 2012
INCREASINGLY GUSTY SOUTHWEST FLOW ON BACKSIDE OF NEW ENGLAND
CENTERED HIGH PRESSURE ONCE AGAIN SPREADING ABOVE NORMAL WARMTH
ACROSS THE NORTH WOODS...WITH MID MORNING READINGS ALREADY PUSHING
40 DEGREES ALONG THE LAKE MICHIGAN SHORELINE. THESE TRENDS SHOULD
CONTINUE...WITH MAINTENANCE OF GUSTY SOUTHWEST WINDS RESULTING IN
AFTERNOON HIGHS MAKING A RUN INTO THE LOWER AND MIDDLE 40S. DESPITE
JUST OFF THE DECK LOW LEVEL WIND MAX...UPWARDS OF 40 KNOTS AT H925
PER LATEST HIGH RES RAP GUIDANCE...SHALLOW MIXING PREVENTING FULL
WIND POTENTIAL FROM REACHING THE SURFACE...SAFELY PUTTING WIND GUSTS
BELOW ADVISORY CRITERIA. STILL NO DOUBT A WINDY ONE...WITH GUSTS
THIS AFTERNOON LIKELY TOPPING 30 MPH. STILL A PLETHORA OF MID AND
UPPER LEVEL CLOUDS...ESPECIALLY ACROSS THE NORTH HALF OF THE
AREA...AHEAD OF LOW AMPLITUDE WAVE PIVOTING EAST ACROSS NORTHWEST
WISCONSIN/WESTERN LAKE SUPERIOR. SOME LIGHT RETURNS NOTED OVER
EASTERN UPPER MICHIGAN THIS MORNING FALLING FROM 11KFT CLOUD
DECK...ALTHOUGH DEARTH OF SUB H70 MOISTURE (SEE LOCAL 12Z SOUNDING)
PREVENTING ANYTHING FROM REACHING THE SURFACE. SOMEWHAT DEEPER
MOISTURE/FGEN DYNAMICS ASSOCIATED BACK CLOSER TO THE WAVE...WHERE
SOME LIGHT SNOW IS REACHING THE SURFACE. DEEPEST MOISTURE AND FGEN
DYNAMICS LOOK TO SLIDE ACROSS LAKE SUPERIOR THIS AFTERNOON...KEEPING
MOST...IF NOT ALL...RAIN/SNOW NORTH OF EASTERN UPPER. MAY YET SEE A
FEW SPRINKLES/FLURRIES...AND WILL SIMPLY RIDE WITH THIS GOING
INHERITED THEME.
UPDATE ISSUED AT 635 AM EST THU DEC 13 2012
FRESHENED UP SKY COVER GRIDS BASED ON SATELLITE TRENDS...OTHERWISE
NO MAJOR FORECAST CHANGES.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 348 AM EST THU DEC 13 2012
EARLY MORNING SURFACE ANALYSIS FINDS A WAVY FRONTAL BOUNDARY THAT
EXTENDS FROM NORTHWEST QUEBEC...BACK ACROSS NORTHERN ONTARIO TO A
FRONTAL WAVE OVER NORTHEAST MINNESOTA. ANOTHER QUASI-WARM FRONT RAN
NORTHWEST-SOUTHEAST FROM EASTERN LAKE SUPERIOR INTO THE LOWER GREAT
LAKES/NORTHERN NEW YORK. TIGHT GRADIENT BETWEEN THE MINNESOTA LOW
AND A 1031MB HIGH OVER WESTERN PENNSYLVANIA FUNNELING INCREASING
SOUTHERLY WINDS INTO MICHIGAN EARLY THIS MORNING. MAIN CENTERS OF
ACTION ALOFT ARE A DIGGING TROUGH INTO SOUTHERN CALIFORNIA...AND
ANOTHER SHORT WAVE TROUGH LIFTING OUT OVER THE SOUTHEASTERN U.S..
WATER VAPOR IMAGERY ALSO REVEALS A SMALL VORTICITY CENTER OVER THE
DAKOTAS ASSOCIATED WITH A 60KT MID LEVEL JET STREAK. WARM ADVECTION
HAS DRAGGED MID/HIGH CLOUDS ACROSS THE FORECAST AREA EARLY THIS
MORNING...WITH RADAR RETURNS ACROSS NORTHERN MICHIGAN EXTENDING BACK
ACROSS THE UPPER PENINSULA. BUT DRY AIR BELOW 725MB PER 00Z APX/GRB
SOUNDINGS PRECLUDING MUCH IN THE WAY OF SURFACE PRECIPITATION
REPORTS (SOME LIGHT PRECIP AT ERY/YAM).
SURFACE WAVE OVER MINNESOTA EXPECTED TO HEAD EAST-NORTHEAST TODAY
TOWARD WEAK PRESSURE FALL CENTER NORTH OF LAKE SUPERIOR. ASSOCIATED
FRONTAL BOUNDARY WILL GET STRETCHED IN A NORTHEAST-SOUTHWEST
FASHION ACROSS THE UPPER MIDWEST AND THE UPPER PENINSULA...WITH THE
BOUNDARY EXPECTED TO DROOP INTO THE STRAITS REGION OVERNIGHT. SHEAR
VORTICITY CENTER OVER THE DAKOTAS WILL EVENTUALLY SLIDE ACROSS
NORTHERN MICHIGAN THIS AFTERNOON. BUT OVERALL FORECAST CONCERNS ARE
MINIMAL...MAINLY DEALING WITH TEMPERATURES/WINDS TODAY...AND
TEMPERATURES TONIGHT WITH THE SAGGING COLD FRONT.
NORTH-SOUTH "GRADIENT" IN CLOUD COVER EXPECTED TODAY WITH SATELLITE
TRENDS SUPPORTING THE IDEA OF THICKER MID CLOUDS REMAINING ACROSS
UPPER MICHIGAN TODAY...AIDED BY ARRIVAL OF ABOVE MENTIONED SHORT
WAVE/SHEAR VORTICITY CENTER...WHILE CLOUD COVER THINS OUT FROM NORTH
TO SOUTH ACROSS THE LOWER PENINSULA. 00Z 850MB ANALYSIS SHOWS AN
AREA OF HIGHER DEW POINTS ACROSS EASTERN SOUTH DAKOTA/NORTHERN
MINNESOTA THAT GETS PULLED EAST ACROSS THE UPPER PENINSULA...AND
WITH THE ARRIVAL OF ADDITIONAL FORCING LATER TODAY QUESTION IS THERE
WHERE DRY LAYER CAN BE ERODED SUFFICIENTLY TO ALLOW FOR SOME LIGHT
PRECIPITATION. PROBABLY NOT WORTH A MEASURABLE POP MENTION OUTSIDE
OF MAYBE WHITEFISH BAY AND POINTS NORTH. WINDS ARE GOING TO BE
ANOTHER CONCERN...WITH FORECAST SOUNDINGS SHOWING TYPICAL INABILITY
TO DEPICT MIXING OVER SNOW COVER. A 30-40KT SOUTHWESTERLY LOW LEVEL
JET RIGHT OFF THE DECK (3K FEET AGL WIND OFF KAPX VWP ALREADY
35-40KT) WON`T REQUIRE MUCH MIXING TO PULL STRONGER GUSTS DOWN TO
THE SURFACE (EVIDENT IN 35KT GUST IN ERY 0735Z OB...THOUGH POSSIBLY
AIDED BY EVAPORATIVE COOLING WITH SOME LIGHT RAIN AT THE TIME).
ANTICIPATE WIND GUSTS OF 30-40 MPH ACROSS NORTHERN LOWER THIS
AFTERNOON...DIMINISHING TOWARD EVENING. TEMPERATURES ALREADY ON THE
WAY UP THIS MORNING...WITH WIDESPREAD MID/UPPER 30S WITH A FEW 40
DEGREE READINGS. A MILD START COMBINED WITH GOOD MECHANICAL MIXING
SHOULD PUSH TEMPERATURES WELL INTO THE 40S THIS AFTERNOON...A GOOD
10-15 DEGREES ABOVE MID DECEMBER NORMALS.
STRETCHED OUT COLD FRONT GRADUALLY SINKS INTO UPPER MICHIGAN AND THE
STRAITS REGION OVERNIGHT. GOOD DEAL OF POST-FRONTAL LOW CLOUD
ALREADY IN PLACE...AND COMBINED WITH LOW LEVEL COLD ADVECTION
LEADING TO SHALLOW INSTABILITY DEVELOPING OVER LAKE SUPERIOR AND FAR
NORTHERN LAKE MICHIGAN...EXPECT SKIES TO REMAIN ON THE CLOUDY SIDE
ACROSS UPPER MICHIGAN TONIGHT...WITH CLOUDS SPILLING INTO NORTHERN
LOWER MICHIGAN OVERNIGHT WITH THE FRONT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 348 AM EST THU DEC 13 2012
FRIDAY...500 MB HEIGHTS RISE AND THE 850 MB TEMPERATURES REMAIN
AROUND 0C IN N LOWER. 850 MB RH IS AROUND 50% AND WITH THE
MID-LEVELS (700-500 MB) STILL PRETTY DRY. THIS WILL LEAVE THE REGION
DRY.
FRIDAY NIGHT...THE MOISTURE FROM THE NEXT SYSTEM MOVES INTO THE
REGION AND CLOUDS WILL INCREASE. LOOKS LIKE WITH THE 500 MB RIDGE
OVER US THAT THE RAIN/SNOW WILL BE HELD OFF UNTIL THE DAY ON
SATURDAY.
SATURDAY...AS THE LOW MOVES OUT OF THE CENTRAL PLAINS, THE MOISTURE
MOVES ACROSS THE REGION. BOTH MODELS START OUT WITH 850 MB
TEMPERATURES OVER NW LOWER WARM ENOUGH TO PRODUCE SNOW/RAIN/FREEZING
RAIN IN THE MORNING. HOWEVER, BY THE AFTERNOON, IT LOOKS LIKE A
SNOW/RAIN MIX ON THE ECMWF AS THE BELOW 0C AIR AT 850 MB HAS DROPPED
SOUTH INTO S LOWER. THIS SEEMS TO BE FROM EVAP COOLING. THE ECMWF
SOUNDINGS FOR 12Z SHOWED A LAYER OF DRY AIR OVER THE FORECAST AREA,
THAT WOULD ALLOW THE COOLING AT 850 MB. THE GFS SHOWS THE MOISTURE
MOVING IN RAPIDLY AND ALLOWING THE WARMER AIR CONTINUE SO THAT IT IS
ONLY RAIN IN THE SOUTHERN COUNTIES OF THE FORECAST AREA. SO LOOKS
LIKE THERE IS A CHANCE FOR RAIN OR SNOW OR SOME KIND OF MIX.
OVERNIGHT, THE MODELS CONTINUE THE TOSS UP, HOWEVER, IT DOES LOOK
LIKE E UPPER SHOULD BE COLD ENOUGH FOR A SNOW ONLY FORECAST FROM THE
OUTSET. HOWEVER, THE AMOUNTS SHOULD BE MINOR TO LIGHT AS E UPPER
REMAINS A GOOD DISTANCE FROM THE MAIN FORCING. OVERNIGHT, THE WARMER
AIR MOVES INTO AN AREA SOUTH AND EAST OF A LINE FROM APN TO MBL. SO
WILL HAVE RAIN LIKELY, AND A RAIN/SNOW MIX NORTH AND WEST TO THE
STRAITS, NORTH OF WHICH WILL BE ALL SNOW. AFTER THE ECMWF MADE ITS
COURSE CORRECTION A COUPLE OF DAYS AGO, IT LOOKED LIKE IT WAS
HOLDING PRETTY CONSISTENT ON THE TRACK OF THE LOW ALONG I-96.
HOWEVER, WITH THE 00Z, THE ECMWF HAS INTRODUCED WARM AIR AT 850 MB
FARTHER NORTH IN N LOWER, SO THAT NOW SATURDAY NIGHT LOOKS LIKE RAIN
UP TO M-72 AND RAIN OR SNOW NORTH.
EXTENDED (SUNDAY THROUGH WEDNESDAY)...SUNDAY, AND THIS WARM TRACK
FOR THE ECMWF CONTINUES ON INTO THE DAY AND NOT UNTIL THE SFC LOW
MOVES EAST OF THE REGION WILL THE COLD AIR MOVE BACK INTO THE REGION
AND SNOW BECOMES DOMINATE AGAIN AND THAT DOESN`T LOOK LIKELY UNTIL
SUNDAY NIGHT. CONSIDERING THE LIKELIHOOD OF THE EAST COASTAL SYSTEM
BEGINNING TO DEVELOP, NOT SURE WHICH MODEL HAS THE UPPER HAND.
MONDAY, NE TO N FLOW WITH THE 850 MB TEMPERATURES IN N LAKE MICHIGAN
AROUND -6C PUTS US AROUND 13-14C DELTA T. SO MARGINAL DELTA T AND NE
FLOW DOESN`T DO MUCH LES IN NW LOWER. IN NE LOWER, THE 850 MB
TEMPERATURES ARE WARMER, SO UNLIKELY THERE WILL BE MUCH IN THE WAY
OF ENHANCEMENT. TEMPERATURE CONTINUE TO COOL AND THE WINDS GO NNW
OVERNIGHT, SO HAVE INCREASED THE POPS TO ALLOW SOME CHANCE POPS IN
THE NNW FLOW AREAS. TUESDAY, THE REAL COLD AIR WITH THIS SYSTEM
STAYS BOTTLED UP UNTIL TUESDAY MORNING WITH THE SYSTEM MOVING UP THE
EAST COAST AND THE WINDS OUT OF THE NW OVER THE FORECAST AREA. SO
BUMPED UP THE POPS FOR LOW CHANCE SNOW FROM LES. WEDNESDAY, THE 500
MB RIDGE MOVE THROUGH THE REGION AND THE WINDS REVERSE OUT OF THE SE
AGAIN. THIS BRINGS WARM AIR NORTH AHEAD OF THE NEXT FRONT. THE GFS
HAS SOME SNOW, AND THE ECMWF IS DRY, SO LOW CHANCE POPS FOR SNOW FOR
NOW.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 635 AM EST THU DEC 13 2012
VFR PREVAILING CONDITIONS EXPECTED THROUGH TONIGHT. GUSTY WINDS
TODAY FROM THE SOUTHWEST...PERHAPS A BRIEF PERIOD OF LOW LEVEL
WIND SHEAR THIS EVENING BEFORE WINDS SLACK OFF.
&&
.MARINE...
ISSUED AT 348 AM EST THU DEC 13 2012
GUSTY SOUTH/SOUTHWEST WINDS THIS MORNING...WITH SOME MARGINAL GALE
FORCE GUSTS ON NORTHERN LAKE MICHIGAN. WILL KEEP GALE WARNINGS FOR
THIS MORNING ON NORTHERN LAKE MICHIGAN...WHICH WILL NEED TO
TRANSITION OF SMALL CRAFT ADVISORIES FOR AT LEAST THIS AFTERNOON IF
NOT INTO TONIGHT DUE TO CHOPPY SEAS. ALSO ANTICIPATE SMALL CRAFT
ADVISORIES FOR REMAINING NEARSHORE ZONES THROUGH TODAY WITH THE
POSSIBLE EXCEPTION OF WHITEFISH BAY. WIND SPEEDS WILL DROP THIS
EVENING AND WINDS WILL VEER TO A MORE WEST OR NORTHWEST DIRECTION AS
A COLD FRONT SAGS ACROSS THE UPPER PENINSULA.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
LHZ345>349.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR LMZ323.
GALE WARNING UNTIL 11 AM EST THIS MORNING FOR LMZ341-342-344>346.
LS...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR LSZ322.
&&
$$
UPDATE...MB
SYNOPSIS...JSL
SHORT TERM...JPB
LONG TERM...JSL
MARINE...JPB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1247 AM EST THU DEC 13 2012
.UPDATE...
ISSUED AT 934 PM EST WED DEC 12 2012
STRONG S WINDS...WITH GUST AS HI AS 40 MPH AT PARENT BAY ON THE
SHORE OF SCHOOLCRAFT COUNTY UNDER 37KT WIND REPORTED ON THE 00Z GRB
RAOB AT 2K FT AGL...IN ADVANCE OF LO PRES IN MN HAS LIFTED
TEMPERATURES INTO THE 30S AT MOST LOCATIONS. SO TENDED TO BUMP UP
TEMPS A COUPLE OF DEGREES FM PREVIOUS FCST UNDER MID/HI OVC. WINDS WL
DIMINISH LATER...SO TEMPS MIGHT FALL AGAIN A BIT LATER.
&&
.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 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1243 AM EST THU DEC 13 2012
WITH SW FLOW OF DRY AIR TO THE S OF WARM FNT OVER NRN LK SUP...
EXPECT VFR CONDITIONS TO PREDOMINATE THRU SUNRISE. THERE WL BE SOME
LLWS OR GUSTY WINDS AT ALL 3 SITES FOR THE FIRST COUPLE HRS AFTER
TAF ISSUANCE UNTIL LLJ PASSES FARTHER TO THE E. THEN A COLD FNT WL
PRESS SEWD THRU THE UPR LKS LATER TODAY. WITH RELATIVELY SHALLOW
INFUSION OF COLDER/MOISTER AIR BEHIND THE FROPA...CONDITIONS ARE
LIKELY TO FALL TO MVFR FIRST AT CMX BY NOON...AT IWD BY MID
AFTN...AND THEN AT SAW EARLY IN THE EVNG. BEST CHC FOR SOME
-SN/-FZDZ AND IFR CONDITIONS WL BE AT CMX/IWD WITH A BIT OF AN
UPSLOPE WNW WIND BEHIND THE FROPA.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 934 PM EST WED DEC 12 2012
UPDATE FOR 10 PM LAKE ISSUANCE...OPTED TO ISSUE GALE WARNING FOR THE
2 EAST ZONES GIVEN SHIP OB OF GUST UP TO 41 KTS AND 01Z CARIBOU
ISLAND REPORT OF 33 KT GUST. THE 00Z GREEN BAY WI RAOB SHOWED A 37KT
WIND AT 2K FT AGL...AND SUSPECT THIS HIER MOMENTUM WILL IMPACT THE E
PART OF LK SUP TO THE S OF PRES FALL CENTER THAT IS FORECAST TO DRIFT
ACROSS THE N PORTIONS OF THE LK THRU EARLY THU MORNING. RATHER
UNSTABLE TEMP PROFILE ALSO SHOULD SUPPORT MIXING OF THE HIER WINDS.
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...
GALE WARNING UNTIL 4 AM EST EARLY THIS MORNING FOR LSZ266-267.
LAKE MICHIGAN...
GALE WARNING UNTIL 7 AM EST THIS MORNING FOR LMZ248-250.
GALE WARNING UNTIL 5 AM EST EARLY THIS MORNING FOR LMZ221.
&&
$$
UPDATE...KC
SHORT TERM...VOSS
LONG TERM...TK
AVIATION...KC
MARINE...VOSS/KC
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
359 PM CST THU DEC 13 2012
.DISCUSSION...
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.../18Z TAF ISSUANCE/
/ISSUED 1145 AM CST THU DEC 13 2012/
COLD FRONT EXITING SLOWLY TO THE EAST THIS AFTERNOON. BAND OF MVFR
CLOUDS BEHIND THE FRONT...BKN AT THE MOMENT AND HIGHER CLOUDS TO
THE NORTH. MODELS CONTINUE TO INDICATE FURTHER DEVELOPMENT TO THE
SOUTH AND WEST DURING THE AFTERNOON. WILL TREND TO MVFR OVER THE
SOUTHERN AND EASTERN SITES THIS AFTERNOON. AM UNCERTAIN ONTO HOW
QUICKLY AND HOW MUCH CLOUDS WILL REMAIN INTO THE NIGHT. VARIOUS
PROG CHARTS INDICATE MAINTAIN MVFR CONDITIONS THROUGH THE NIGHT.
LATEST RAP DOES SHOW THIS AS WELL. WILL HOLD ONTO THE MVFR AND
LOWER SOME INTO THE NIGHT...GOING IFR TO THE NORTH AS IN THE
PREVIOUS FORECAST. WILL ALSO INCLUDE SOME MVFR VSBYS IN FOG IF WE
RETAIN CLOUDS OVERNIGHT. LIGHT NORTH/NORTHWEST WIND THIS
AFTERNOON...LIGHT/VRBL OVERNIGHT BECOMING EAST SOUTHEAST AHEAD OF
DEVELOPING LOW PRESSURE SYSTEM FRIDAY.
KMSP...MODELS CONTINUE TO SUGGEST AT LEAST BKK025 MOVING INTO THE
PICTURE THIS AFTERNOON. WILL MENTION THAT AFTER 21Z. ALSO WILL
MAINTAIN LOW CLOUDS INTO TONIGHT AFTER COLLABORATION WITH VARIOUS
PARTNERS. THIS SHOULD EVENTUALLY LIFT NORTH AND WEST AGAIN INTO
FRIDAY AS LOW LEVEL FLOW BECOMES MORE SOUTHEAST. SURFACE WINDS WILL
REMAIN NORTH/NORTHWEST AND LIGHT THIS AFTERNOON WITH THE MORE EAST
SOUTHEAST FLOW INTO FRIDAY. ANY PRECIPITATION WILL HOLD OFF UNTIL
LATER FRIDAY NIGHT.
/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.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
943 PM CST FRI DEC 14 2012
.UPDATE...
LOWERED TEMPERATURES AND ADJUSTED PRECIPITATION TYPES FOR LOWER
TEMPERATURES. LOADED NEW WINDS AND WIND GUSTS.
&&
.PREV DISCUSSION... /ISSUED 746 PM CST FRI DEC 14 2012/
AVIATION...
AREAS OF LIGHT RAIN WILL SPREAD TO THE NORTHEAST OVER WESTERN
NEBRASKA THIS EVENING. CEILINGS WILL LOWER INTO MVFR CATEGORIES
AFTER 1506Z. CEILINGS WILL RISE INTO VFR CATEGORIES SATURDAY
MORNING OVER WESTERN NEBRASKA.
PREV DISCUSSION... /ISSUED 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.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...POWER
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
746 PM CST FRI DEC 14 2012
.AVIATION...
AREAS OF LIGHT RAIN WILL SPREAD TO THE NORTHEAST OVER WESTERN
NEBRASKA THIS EVENING. CEILINGS WILL LOWER INTO MVFR CATEGORIES
AFTER 1506Z. CEILINGS WILL RISE INTO VFR CATEGORIES SATURDAY
MORNING OVER WESTERN NEBRASKA.
&&
.PREV DISCUSSION... /ISSUED 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.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...POWER
AREA FORECAST DISCUSSION
NWS BISMARCK ND
328 AM CST THU DEC 13 2012
.SHORT TERM...TODAY THROUGH FRIDAY...
THE HIGHLIGHT OF THE SHORT TERM IS PERSISTENT STRATUS AND ITS
IMPACT ON TEMPERATURES.
WIDESPREAD STRATUS IS IN PLACE ACROSS NORTH DAKOTA...MUCH OF
EASTERN MONTANA AND INTO SASKATCHEWAN AND ALBERTA. WITH A WEAK LOW
LEVEL WIND FIELD WITH WEAK WARM AIR ADVECTION REINFORCING THE
INVERSION TO TRAP THE STRATUS...EXPECT THE LOW LEVEL CLOUD COVER
TO LAST THROUGH AT LEAST TOMORROW MORNING...WITH THE LATEST RUNS
OF THE HRRR AND RAP KEEPING THE STRATUS ACROSS THE AREA THROUGH
THEIR ENTIRE VALID PERIODS. AS A RESULT...TEMPERATURE RECOVERY
THROUGH THE DAY WILL BE WEAK. MOST PLACES ARE ONLY EXPECTED TO RECOVER
ABOUT 5 DEGREES OR SO FROM MORNING LOWS...WITH HIGHS IN THE SINGLE
DIGITS NORTH TO THE UPPER 20S FAR SOUTHWEST. DID ADD FLURRIES TO
THE ENTIRE AREA THROUGH TODAY UNDER THE STRATUS...WITH A MENTION
OF MORNING FOG ACROSS THE SOUTHWEST IN WEAK UPSLOPE FLOW.
FOR TONIGHT...WITH STRATUS IN PLACE TEMPERATURES DECLINES WILL
ALSO BE MINIMAL...AGAIN ABOUT 5 DEGREES AT THE MOST FOR MUCH OF
THE AREA. DID NOT ADD FOG...HOWEVER...THIS WILL HAVE TO BE
MONITORED AS A BUILD DOWN OF THE STRATUS MAY BE POSSIBLE.
THE FORECAST FOR FRIDAY IS A BIT UNCERTAIN AS THE MODELS DO NOT
HAVE THE BEST HANDLE ON THE STRATUS EVOLUTION FOR TODAY. DID TRY
TO HOLD THE STRATUS THROUGH THE MORNING HOURS ON
FRIDAY...HOWEVER...WOULD NOT BE SURPRISED IF THE STRATUS HOLDS
LONGER UNDER AN INVERSION THAT IS REINFORCED BY STRONGER WARM
AIR ADVECTION. THUS...IMPACTS ON THERMAL FIELDS FROM SKY COVER ARE
SIGNIFICANT FOR FRIDAY.
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
BROAD CYCLONIC FLOW OVER CONUS WITH BELT OF STRONGEST
WESTERLIES WELL SOUTH OF THE REGION. WESTERN AND CENTRAL NORTH
DAKOTA GENERALLY CUTOFF FROM GULF MOISTURE WITH MAJOR SYSTEMS
SHUNTED FAR TO THE SOUTH. TEMPERATURES ARE MODERATE SLIGHTLY BELOW
NORMAL WITH NO MAJOR COLD OUTBREAKS. NO PRECIPITATION IS GENERATED
BY A BLEND OF MODEL SOLUTIONS THOUGH NEAR THE END OF THE EXTENDED
ECMWF BRINGS MORE SIGNIFICANT SYSTEM TO THE NORTHERN PLAINS WHICH IS
NOT SEEN IN THE GEFS.
&&
.AVIATION...
MOIST AIRMASS TRAPPED BENEATH DOME OF HIGH PRESSURE WILL
BRING MVFR TO IFR CEILINGS TO WESTERN AND CENTRAL NORTH DAKOTA. SOME
LINGERING FLURRIES AND FOG ARE POSSIBLE IN THE EAST AND IN THE
SOUTHWEST WHERE GREATEST UPSLOPE FLOW IS OCCURRING.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...AYD
LONG TERM/AVIATION...HW
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
1226 AM CST THU DEC 13 2012
.UPDATE...BAND OF SNOW HAS NOW SET UP ALONG I-94 IN NORTH DAKOTA
AND EASTWARD INTO MINNESOTA. BISMARCK RECEIVED ABOUT 3 INCHES THIS
EVENING...AND ANTICIPATE 1-3 INCHES ALONG THIS NARROW BAND BY
MORNING. 05Z RAP INDICATES THE BAND WILL HOLD TOGETHER THROUGH THE
FA (ALTHOUGH ITS LOCATION IS TOO FAR SOUTH) WITH UP TO 3 INCHES
POSSIBLE.
&&
.AVIATION...EXPECT MVFR CIGS THROUGH THE PERIOD WITH SOME LIGHT
SNOW POSSIBLE LATER TONIGHT INTO THU. WINDS SHOULD BE NORTHERLY
WITH HIGH PRESSURE BUILDING IN FROM CANADA. VSBYS COULD LOWER INTO
IFR RANGE NEAR KFAR FROM A BETTER DEFINED SNOW BAND IF IT
DEVELOPS...SO WE WILL MONITOR THIS POTENTIAL.
&&
.PREV DISCUSSION... /ISSUED 754 PM CST WED DEC 12 2012/
DISCUSSION...
THE MAIN CHALLENGE OVERNIGHT WILL BE SNOW POTENTIAL IN A FAIRLY
NARROW BAND ALONG THE I 94 CORRIDOR. A MID LEVEL BAND OF FGEN IN
THE 850-700MB LEVEL IS SETTING UP FROM KDIK-KBIS THIS
EVENING...AND EXPECT THIS TO PROGRESS TO THE E/NE OVERNIGHT. THE
GFS HAD THE BEST HANDLE ON THIS...AND THE RAP SLOWLY WEAKENS THIS
SNOW OVERNIGHT WITH SFC HIGH BUILDING IN. THE INHERITED POPS
REALLY LOOK GOOD WITH THE POTENTIAL FOR UP TO AN INCH OF SNOW IN A
NARROW BAND...SO WILL MAINTAIN THIS POTENTIAL. THESE SNOW BANDS
SOMETIMES DEVELOP A BIT MORE THAN MODELS INDICATE...SO WILL
CONTINUE TO MONITOR...BUT GRIDS ARE IN GOOD SHAPE. WILL RAISE
OVERNIGHT MINIMUMS IN THE NORTH AND THE SOUTH...WITH PLENTY OF
CLOUDS AND COOLING RELYING ON LOW LEVEL CAA BEHIND THE COLD FRONT.
PREV DISCUSSION... /ISSUED 230 PM CST WED DEC 12 2012/
DISCUSSION...FORECAST CHALLENGE CONCERNS TEMPERATURES AND SNOW
CHANCES. MODELS SHOWING SOME MINOR DIFFERENCES WITH SNOW BAND LATE
TONIGHT INTO TOMORROW AND WILL CONTINUE WITH A BLEND.
NEXT WAVE PUSHING INTO WESTERN WYO IN MID LEVEL ZONAL FLOW AND WILL
IMPACT THE REGION LATE TONIGHT INTO THURSDAY. MAIN JET AXIS THROUGH
THE CENTRAL PLAINS AND UPPER SUPPORT AT THIS TIME LOOKS RELATIVELY
WEAK. THERE IS A BAND OF LOWER CONDENSATION PRESSURE DEFICIT/MODEST
ISENTROPIC LIFT AND FRONTOGENETIC FORCING GENERALLY BETWEEN HIGHWAY
2 AND I 94 FROM MIDNIGHT ON. MODELS HAVE BEEN RELATIVELY CONSISTENT
WITH THIS AND WILL INCREASE POPS. AT THIS POINT WITH RELATIVELY WEAK
ABOVE MENTIONED FORCING MECHANISMS FEEL GENERAL SNOW AMOUNTS IN THE
1-2 INCH RANGE LOOK REASONABLE AT THIS TIME INTO MID DAY THURSDAY.
BAROCLINIC ZONE SAG SLOWLY SOUTH TONIGHT HOWEVER EXTENSIVE CLOUD
LAYER SHOULD LIMIT DROP TONIGHT. COULD STILL SEE A FAIRLY
RESPECTABLE TEMPERATURE CONTRAST ACROSS THE REGION WITH COLDEST
TEMPERATURES ACROSS FAR NORTH WHERE TEMPERATURES CURRENTLY BLO
ZERO.
MODELS DIFFER ON DURATION OF -SN ALONG NARROW CORRIDOR THURSDAY
HOWEVER WOULD EXPECT BAND TO SHIFT EAST WITH WAVE REPRESENTED BY
NAM/GFS 290K ISENTROPIC SURFACE AND WILL TIME POPS ACCORDINGLY. LOW
LEVEL RH REMAINS IN PLACE SO CLOUD TRENDS WITH WAVE PASSAGE IN
QUESTION. WITH LIGHT MIXING AS SURFACE HIGH BUILDS IN TEMPERATURE
RECOVER WILL BE MINOR AND HAVE TRIMMED BACK ON MAXIMUM VALUES.
SHOULD BE QUIET REMAINDER OF WORK WEEK WITH SLIGHTLY MODERATING
THERMAL COLUMN. LOW LEVEL RH REMAINS ACROSS FA SO CLOUDS REMAIN A
QUESTION AND THIS TIME OF YEAR A MAJOR PLAYER WITH TEMPERATURES.
GEM A SIGNIFICANT OUTLIER WITH NORTHWARD EXTEND OF QPF FRIDAY NIGHT
AND WILL BE DISCARDED. NAM/ECMWF STILL CLIP FAR SE-E FA SAT AND WILL
MAKE SOME MINOR POP ADJUSTMENTS.
LONG TERM... /SAT NIGHT THROUGH WED/
LONG TERM MODELS IN REASONABLE AGREEMENT EARLY IN THE PERIOD...BUT
DIVERGE SIGNIFICANTLY FOR EARLY NEXT WEEK. STRONG LOW PRESSURE
SYSTEM EXPECTED TO LIFT OUT OF THE CENTRAL PLAINS AND INTO THE GREAT
LAKES OVER THE WEEKENDS...WITH WRAP AROUND SNOW POSSIBLY IMPACTING
MY EASTERN ZONES SAT NIGHT AND SUN. 12Z ECWMF MORE IN LINE WITH THE
00Z/12Z GFS...WHICH PULLS PRECIP OUT OF THE AREA BY NOON SUN. PREV
ECMWF KEPT LINGERING PRECIP IN THE EAST THROUGH MONDAY. GFS THEN
SIGNIFICANTLY DIVERGES FROM ECWMF WITH A CLIPPER LIKE SYSTEM MOVING
ACROSS NORTHERN TIER MON NIGHT INTO TUE. CURRENT ALLBLEND SOLUTION
CONTINUES TO KEEP A DRY FCST IN FOR TUE...BUT GFS SOLUTION WOULD
CERTAINLY BRING SNOW SNOWFALL ACROSS OUR NORTHERN ZONES MON NIGHT
AND TUE. DUE TO LOW CONFIDENCE...WILL GO WITH DRY SOLUTION.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
TG
AREA FORECAST DISCUSSION
NWS TULSA OK
729 PM CST FRI DEC 14 2012
.DISCUSSION...
THE 00Z TAF DISCUSSION CAN BE FOUND BELOW.
&&
.AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM.
SHOWERS AND POSSIBLY AN ISOLATED TSRA OR TWO WILL AFFECT THE
TERMINALS TONIGHT THROUGH 07Z. VFR CIGS WILL TREND TOWARD MVFR
WITH TIME...EVEN IFR OVER IN NW AR TOWARD 12Z. SKIES WILL CLEAR
FROM WEST TO EAST ON SATURDAY. STRONG WINDS FROM THE SOUTH...THEN
SOUTHWEST ON SATURDAY WILL GUST AOA 25 KTS IN SOME PLACES.
LACY
&&
.PREV DISCUSSION... /ISSUED 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 46 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 / 90 10 10 10
BYV 46 66 40 61 / 90 10 10 10
MKO 45 69 39 64 / 90 10 10 10
MIO 45 66 37 59 / 90 10 10 10
F10 45 69 42 64 / 80 10 10 10
HHW 47 71 43 69 / 80 10 10 10
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
AR...NONE.
&&
$$
AVIATION...30
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
943 PM MST FRI DEC 14 2012
.UPDATE...
&&
.SHORT TERM...DEEP WEAK LIFT HAS SHIFTED EAST OF COLORADO...SOME
FOG REMAINS NEAR THE EASTERN BORDER BUT NORTHWEST WINDS ARE
DEVELOPING THAT SHOULD MIX/SCOUR THAT OUT OVER THE NEXT FEW HOURS.
MEANWHILE THERE IS A DECENT BATCH OF CONVECTION BEHIND THE TROUGH
AXIS OVER THE MOUNTAINS DUE TO A LITTLE BURST OF WIND AND
INSTABILITY...WHICH SHOULD CONTINUE FOR SEVERAL MORE HOURS AND
THEN DIMINISH. MEANWHILE THERE IS SOME CLEARING BEHIND THE TROUGH
AXIS EAST OF THE FRONT RANGE. WITH TEMPERATURES APPROACHING OUR
FORECAST LOWS AND NOT MUCH WIND IN THE LOW SPOTS...I LOWERED
TONIGHTS LOWS A LITTLE.
&&
.AVIATION...WINDS TRENDING BACK TO TYPICAL DRAINAGE PATTERN AT
THIS TIME WITH A LITTLE WESTERLY ENHANCEMENT. SLIGHT CHANCE OF
LIGHT SHOWERS IN DENVER SATURDAY AFTERNOON AND EVENING...AND A
SLIGHT CHANCE OF NEEDING ILS APPROACHES TO KDEN DURING THAT TIME.
&&
.PREV DISCUSSION... /ISSUED 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/UPDATE...GIMMESTAD
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1135 PM CST FRI DEC 14 2012
.UPDATE...
HAVE UPDATED THE FORECAST TO MAINLY DELAY PRECIP ONSET ACROSS THE
AREA WITH MUCH OF THE AREA NOT EXPECTED TO SEE PRECIP UNTIL CLOSER
TO 05Z OR LATER. OTHERWISE DID NOT MAKE ANY OTHER CHANGES...WITH
REMAINDER OF FORECAST ON TRACK AT THIS POINT.
.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...15/06Z
MAINLY MVFR CIGS ACROSS THE CWA CURRENTLY...BUT CIGS EXPECTED TO
LOWER INTO THE IFR RANGE OVERNIGHT WITH POSSIBLE MVFR VSBYS IN
MODERATE RAIN. LATEST HIGH-RES OUTPUT ALSO SUGGESTING AREA SOCKED IN
WITH LIFR CIGS FOR MUCH OF THE DAY SATURDAY...FOR NOW HAVE HINTED AT
LIFR CONDITIONS BUT KEPT MAJORITY OF CIGS IN THE IFR RANGE.
SOUTHERLY WINDS TO SHIFT AROUND TO THE WEST TO NORTHWEST TOWARD THE
END OF THE PERIOD. WIDESPREAD RAINFALL EXPECTED TO END BY MID
MORNING...WITH ANOTHER LITTLE AREA POSSIBLY CLIPPING KDSM AND
IMPACTING KOTM TOWARD LATE MORNING/EARLY AFTERNOON. THEN WRAP-AROUND
PRECIP TO POSSIBLY IMPACT KFOD AND KMCW BY LATE AFTERNOON/SATURDAY
EVENING.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
UPDATE...MJB
SHORT TERM...KS
AVIATION...MJB
LONG TERM...JOHNSON
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1151 PM CST FRI DEC 14 2012
...UPDATED AVIATION DISCUSSION...
.UPDATE...
ISSUED AT 1017 PM CST FRI DEC 14 2012
AS THE UPPER LOW MOVED NORTHEAST, MORE WRAPAROUND PRECIP DEVELOPED
THAN PREVIOUSLY THOUGHT. ADDED 20 TO 30 PERCENT CHANCES FOR
RAINSHOWERS THROUGH ABOUT 09Z, THEN WEANED PRECIP CHANCES
DOWNWARD. I ALSO INCREASED CLOUDS BETWEEN NOW AND SUNRISE.
ADDITIONAL RAINFALL WILL BE LIGHT, WITH ONLY 0.01 TO 0.10 OF AN INCH
ANTICIPATED.
&&
.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 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1150 PM CST FRI DEC 14 2012
A STRONG UPPER LEVEL DISTURBANCE WILL LIFT NORTHEAST OUT OF
WESTERN KANSAS THROUGH THE REMAINDER OF THE OVERNIGHT HOURS. MOST
OF THE HEAVIER SHOWERS AND ISOLATED THUNDERSTORMS HAVE ALREADY
EXITED THE WESTERN PART OF THE STATE. SOME LINGERING WRAPAROUND
LIGHT RAIN ALONG WITH IFR/MVFR CIGS WILL CONTINUE TO IMPACT THE
TAF SITES THROUGH ABOUT 08Z TO 09Z BEFORE MOVING OUT. A SURFACE
LOW OVER WESTERN KANSAS WILL ALSO MOVE NORTHEAST OUT OF THE AREA.
THERE WILL BE A PERIOD OF GUSTY WEST TO SOUTHWEST WINDS BEHIND THE
LOW. VFR CONDITIONS AND DECREASING WINDS WILL RETURN TO WESTERN
AND CENTRAL KANSAS BY 12Z-14Z.
&&
.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.
&&
$$
UPDATE...BURKE
SHORT TERM...KRUSE
LONG TERM...SUGDEN
AVIATION...GERARD
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1138 PM CST FRI DEC 14 2012
...UPDATE TO AVIATION...
.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
&&
.AVIATION...
UPPER TROUGH WILL TRAVERSE THE CWA THE REMAINDER OF THE NIGHT
WITH LINGERING SHOWERS GRADUALLY ENDING BUT WITH IFR/MVFR CIGS
REMAINDER OF THE NIGHT WITH DRY SLOT. CIGS WILL SLOWLY INCREASE
TO 2000-3000 FEET TOWARDS 15Z...THEN LINGER THROUGH REMAINDER OF
THE FCST AS MOISTURE WRAPS AROUND THE DEPARTING SHORTWAVE TROUGH
AND PUSHES STRATUS DECK BACK TO THE SOUTH AGAIN. GUSTY SOUTH TO
SOUTHEAST WINDS WILL DECREASE TO 10 TO 12 KTS AND VEER TO THE
SOUTHWEST TO WEST BEYOND 15Z.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1021 PM CST FRI DEC 14 2012
...UPDATED FOR AN UPDATED FORECAST...
.UPDATE...
ISSUED AT 1017 PM CST FRI DEC 14 2012
AS THE UPPER LOW MOVED NORTHEAST, MORE WRAPAROUND PRECIP DEVELOPED
THAN PREVIOUSLY THOUGHT. ADDED 20 TO 30 PERCENT CHANCES FOR
RAINSHOWERS THROUGH ABOUT 09Z, THEN WEANED PRECIP CHANCES
DOWNWARD. I ALSO INCREASED CLOUDS BETWEEN NOW AND SUNRISE.
ADDITIONAL RAINFALL WILL BE LIGHT, WITH ONLY 0.01 TO 0.10 OF AN INCH
ANTICIPATED.
&&
.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 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 527 PM CST FRI DEC 14 2012
MVFR CIGS AND VSBYS WILL DOMINATE THE TAFS THROUGH ABOUT 04 TO
06Z, WHEN FLIGHT CONDITIONS WILL IMPROVE. A SHORT WAVE IS MOVING
NORTHEAST THROUGH THE TAF SITES RATHER QUICKLY, AND MAY BRING IFR
CIGS FOR A SHORT TIME AS A CONVECTIVE CELL MOVES OVER A TAF SITE.
WINDS WILL BE SOUTH TO SOUTHEAST AT 15G20KTS EARLY, THEN BECOME
SOUTHWEST AT 13G23KTS BEHIND THE UPPER WAVE. A COLD FRONT WAS
MOVING NORTH-NORTHEAST THROUGH FAR SOUTHWESTERN KANSAS AT 5:30 PM,
AND SHOULD MARCH THROUGH GCK AROUND 03Z, THROUGH DDC ABOUT 04Z,
AND PASS HYS AROUND 06Z. THE FRONTAL PASSAGE IS THE BEST TIME FOR
ANY CONVECTION AT EACH TAF SITE.
&&
.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.
&&
$$
UPDATE...BURKE
SHORT TERM...KRUSE
LONG TERM...SUGDEN
AVIATION...BURKE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
447 AM EST SAT DEC 15 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 442 AM EST SAT DEC 15 2012
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A SPLIT FLOW ACRS
NAMERICA WITH ZONAL NRN BRANCH OVER CANADA KEEPING THE REAL COLD
ARCTIC AIR LOCKED TO THE N OF THE BORDER. IN FACT...A LOOK AT THE
00Z H85 RAOBS SHOW TEMPS AT THAT LVL ABV 0C OVER ALL OF THE CONUS
EXCEPT THE NE AND PAC NW. EARLY THIS MRNG...THE UPR GRT LKS ARE
UNDER THE INFLUENCE OF A FAIRLY SHARP NRN BRANCH UPR RDG OVER
ONTARIO...AND LOCAL 00Z RAOBS SHOW A SHAPR SUBSIDENCE INVRN BASE
ARND H925 UNDER MID LVL DRY AIR. THE NEAR SFC LYR IS RATHER
MOIST...SO THERE IS QUITE A BIT OF LO CLD TRAPPED UNDER THIS INVRN.
TEMPS ARE GENERALLY WELL ABV NORMAL...IN THE 25 TO 30F RANGE. TO THE
SW...STRONG NEGATIVELY TILTED DISTURBANCE EMBEDDED IN THE WSW SRN
BRANCH FLOW IS LIFTING NEWD THRU THE CENTRAL PLAINS SUPPORTED BY
130KT H3 JET MAX OVER TX. ALTHOUGH THE MID LVLS OVER THE UPR LKS ARE
DRY...HI CLD WELL IN ADVANCE OF THIS SHRTWV IS SPILLING INTO THE
AREA. THE CLOSEST PCPN IN THE FORM OF RA AT 06Z HAS MOVED INTO
IA/NRN IL IN THE SURGE OF MSTR AHEAD OF THIS SHRTWV ENHANCED BY 50KT
H85 S LLJ OVER THE SRN PLAINS.
MAIN FCST CONCERNS IN THE SHORT TERM ARE MANY AND REVOLVE ARND
TIMING AND TYPE OF PCPN ASSOCIATED WITH DISTURBANCE MOVING NEWD THRU
THE PLAINS. ALTHOUGH NCEP INDICATES A PREFERENCE FOR THE 00Z GFS
GIVEN PRESENT NEGATIVE TILT OF THE DISTURBANCE/STRONG JET MAX
ROTATING NEWD ON ITS ERN FLANK...FCSTS SHOWING THIS DISTURBANCE
WEAKENING AS IT MOVES TOWARD THE NE WITH JET CORE SHEARING OUT THRU
THE GRT LKS INDICATE THE VERY CONSISTENT...FARTHER S 12Z ECMWF MIGHT
BE ON THE RIGHT TRACK. SO OPTED TO USE THE COMPROMISE 00Z NAM FOR
FCST DETAILS. OVERALL GIVEN ANTECEDENT DRY AIR ALF AND TRACK OF
STRONGER DYNAMICS TO THE SE...THIS PCPN EVENT WL NOT BE SGNFT.
TODAY...THIS MRNG SHOULD BE MAINLY PCPN FREE WITH LINGERING MID LVL
DRY AIR. THE ONLY CONCERN IS THE POTENTIAL FOR SOME -DZ/-FZDZ OVER
MAINLY THE CENTRAL ZNS WITH UPSLOPE ESE FLOW OFF LK MI AND THE
ARRIVAL OF BIT HIER H95-9 SPECIFIC HUMIDITY. DEEPER MSTR IS PROGGED
TO ARRIVE THIS AFTN...BUT MODELS REMAIN CONSISTENT SHOWING SHARPEST
H85-5 QVECTOR CNVGC PASSING TO THE SE AS DISTURBANCE WEAKENS AS IT
MOVES OUT OF THE SRN BRANCH TROF OVER THE DESERT SW. THE IMPRESSIVE
JET CORE IS ALSO FCST TO WEAKEN AND SHEAR OUT A BIT JUST S OF THE
LOWER LKS. IN FACT...MODEL QPF IS RATHER MODEST...WITH A BIT MORE
OVER THE SE CWA CLOSER TO THE SHARPER ISENTROPIC ASCENT/QVECTOR
CNVGC/UPR DVGC. TENDED TO CUT POPS FM PREVIOUS FCST A BIT ESPECIALLY
AWAY FM THE SE CWA TO REFLECT THE CONSENSUS ON THE TRACK OF BETTER
DYNAMIC SUPPORT. GIVEN THE WARMTH OF THE AIRMASS IN PLACE...SUSPECT
ANY PCPN WL AT LEAST START AS RA. BUT DRYNESS OF THE MID LVLS AND
POTENTIAL EVAP COOLING MIGHT CAUSE SOME OF THIS PCPN TO AT LEAST MIX
WITH SN...ESPECIALLY OVER THE HIER TERRAIN OF THE CENTRAL. BUT THE
LACK OF SGNFT DYNAMIC FORCING/OMEGA SUGS THIS PROCESS WL NOT BE AS
VIGOROUS AS MIGHT OTRW BE THE CASE. WITH THE SFC LO WEAKENING AS IT
MOVES TO THE NE...TENDED TOWARD THE LOWER SIDE OF GUIDANCE FOR
TEMPS...WHICH IS IN GOOD AGREEMENT WITH PREVIOUS FCST.
TONIGHT...MAIN DISTURBANCE PASSING TO THE SE IS FCST TO SHIFT AWAY
TO THE E...SO SUSPECT PCPN OVER MUCH OF THE CWA WL DIMINISH TO JUST
A BIT OF -RA/-SN PERHAPS -DZ/-FZDZ AFTER 00Z AS GUIDANCE SHOWS
LARGER SCALE QVECTOR DVGC IN PLACE THIS EVNG. ADDED MENTION OF FOG
IN UPSLOPING AREAS OVER MAINLY THE CENTRAL IN LLVL SE FLOW WITH
LINGERING LLVL MSTR UNDER SOME UPR DRYING. BUT SHRTWV EMBEDDED IN
NRN BRANCH IS PROGGED TO BRING A RETURN OF SOME LARGER SCALE QVECTOR
CNVGC/UPR DVGC LATER OVER THE W...SO TRENDED POPS HIER THERE OVERNGT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 442 AM EST SAT DEC 15 2012
SUNDAY...THE MODELS ARE VERY SIMILAR WITH THE OVERALL
PATTERN...INDICATING A LINGERING MID/UPPER LEVEL TROUGH OVER THE
NORTHERN GREAT LAKES AND A DOWNSTREAM BLOCKING RIDGE OVER QUEBEC.
THERE ARE MORE SUBTLE DIFFERENCES WITH THE WEAK SHORTWAVES MOVING
THROUGH NRN WI AND UPPER MI THAT MAY ENHANCE ANY PCPN. WITH
RELATIVELY ABUNDANT MOISTURE IN PLACE OVER THE AREA...THE WEAK TO
MODERATE QVECTOR CONV AND POTENTIAL FOR 800-600 MB FGEN (ESPECIALLY
OVER THE WEST PER NAM) THE FORECAST KEEPS LIKELY POPS GOING BUT FOR
LIGHT QPF...LESS THAN A TENTH OF AN INCH. AT THE SFC...A TROUGH WILL
WILL LINGER OVER UPPER MI...RESULTING IN A RELATIVELY WARM LOW LEVEL
TEMP PROFILE. USING A GFS/NAM/ECMWF COMPROMISE ON LOW LEVEL
TEMPS...EXPECT MAINLY SNOW OVER THE WEST BUT A RAIN/SNOW MIX EAST AND
MAINLY RAIN NEAR LAKE MICHIGAN.
SUNDAY NIGHT INTO MONDAY...THE MORE WIDESPREAD PCPN SHOULD DIMINISH
SUNDAY NIGHT AS THE MID LEVEL AND SFC TROUGHS LIFT TO THE NORTHEAST.
COLDER AIR WILL THEN FILTER INTO THE AREA BRINGING 850 MB TEMPS DOWN
TO NEAR -6C. THE COLD AIR COMBINED WITH MOIST CYCLONIC LOW LEVEL
FLOW MAY SUPPORT SOME LIGHT LAKE ENHANCED SNOW OVER THE NORTH. THE
GREATEST POTENTIAL FOR ANY ACCUMULATING SNOW IS LIKELY OVER THE WEST
WHERE THE ONSHORE FLOW WOULD BE A BIT STRONGER COMPARED TO THE EAST
WHERE ONLY LIGHT WINDS PREVAIL UNDER THE INFLUENCE OF LAKE INDUCED
TROUGHING.
TUE-FRI...MODELS WERE SIMILAR WITH TREND TOWARD A PROGRESSIVE
PATTERN WHICH WILL BRING A MID/UPPER LEVEL TROUGH INTO THE WRN CONUS
TUE AND INTO THE PLAINS BY WED NIGHT. MID LEVEL AND SFC RIDGING
AHEAD OF THIS FEATURE WILL RESULT IN DRY WEATHER WITH TEMPS NEAR OR
SLIGHTLY ABOVE SEASONAL AVERAGES. THERE IS THE POTENTIAL FOR A
SIGNIFICANT STORM SYSTEM BY THU INTO FRI MOVING OUT OF THE PLAINS
TOWARD THE GREAT LAKES. THE GFS/ECMWF BRING THE SFC LOW INTO THE SRN
LAKES WITH POTENTIAL FOR SNOW AND LAKE ENHANCED SNOW OVER UPPER MI.
AS WOULD BE EXPECTED FOR A FORECAST FOR DAYS 5/6... THERE IS STILL
CONSIDERABLE UNCERTAINTY WITH THE PATH AND STRENGTH OF THE SYSTEM.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1220 AM EST SAT DEC 15 2012
EXPECT LOW MVFR TO IFR STRATUS DECK TO HOLD OVER TAF SITES OVERNIGHT
...ESPECIALLY WITH UPSLOPE E-SE FLOW AT KCMX AND KSAW. CONTINUED
UPSLOPE E-SE FLOW AND ONSET OF RAIN/SNOW MIX OVER EXISTING SNOW
COVER WILL LOWER CONDITIONS TO LIFR BY LATE SAT AFTERNOON INTO SAT
EVENING. VLIFR MAY EVEN BE POSSIBLE AT KCMX LATE SATURDAY
AFTERNOON.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 442 AM EST SAT DEC 15 2012
AS LO PRES APPROACHES FROM THE SW...TIGHTENING GRADIENT WILL SUPPORT
AN INCREASING SE WIND INTO TONIGHT. AFTER COORDINATION WITH
ENVIRONMENT CANADA...OPTED TO ISSUE A GALE WARNING FOR THE FAR E...
WHERE THE GRADIENT IS EXPECTED TO BE TIGHTEST AND TERRAIN OFTEN
ACCENTUATES A SE FLOW. OVER THE W WHERE THE GRADIENT WILL BE
WEAKER...WIND SHOULD REMAIN UNDER 25 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING FROM 6 PM THIS EVENING TO 4 AM EST SUNDAY FOR
LSZ267.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...JLB
AVIATION...VOSS
MARINE...KC
AREA FORECAST DISCUSSION
NWS BILLINGS MT
919 PM MST FRI DEC 14 2012
.SHORT TERM...VALID FOR SAT AND SUN...
RADAR IMAGERY AT MID EVENING SHOWS SNOW EXTENDING FROM LIVINGSTON
AND BIG TIMBER NORTHEAST TO HARLOWTON AND RYEGATE...WHERE THERE/S
A BIT OF ENHANCEMENT IN REFLECTIVITY. A MODEST...BUT WELL-DEFINED
AREA OF FRONTOGENESIS IN THE 850-700 HPA LAYER IS LIKELY THE MAIN
FORCING FOR THIS PRECIPITATION IN ADVANCE OF A 500-HPA SHORT WAVE
TROUGH. THE 00 UTC GFS...00 UTC NAM...AND 21 UTC SREF ALL SEEM TO
HAVE A GOOD HANDLE ON THIS...AND PRODUCE ENOUGH QPF FOR PRIMARILY
ONE TO THREE INCHES OF SNOW IN SOUTH CENTRAL MT TONIGHT. BASED ON
RECENT OBSERVATIONAL TRENDS AND THAT MODEL SUPPORT...WE INCREASED
POPS TO BETWEEN 80 AND 100 PERCENT IN SOUTH CENTRAL MT OVERNIGHT.
VISIBILITY IN THE SNOWFALL HAS MAINLY BEEN FROM 1 TO 3 MILES THIS
EVENING...IMPLYING SNOWFALL RATES THAT AREN/T QUITE ENOUGH FOR US
TO NEED AN ADVISORY. HOWEVER...THAT WILL REQUIRE CLOSE MONITORING
GIVEN PERSISTENT FORCING AND INSTABILITY NOTED BY STEEP MID-LEVEL
LAPSE RATES. THE 02 AND 03 UTC RAP RUNS BOTH DO WELL WITH ONGOING
SNOW...AND TAKE LIGHT SNOW INTO BILLINGS BETWEEN 06 AND 09 UTC...
SO LIKELY POPS STILL GOOD HERE AS WELL.
IN SOUTHEASTERN MT...WE REMOVED MOST OF THE FOG MENTION SINCE THE
INCREASE IN CLOUDS SHOULD PREVENT ITS FORMATION...EXPECT MAYBE IN
THE YELLOWSTONE RIVER VALLEY FROM FORSYTH TO MILES CITY. POPS FOR
BAKER AND EKALAKA WERE ALSO REMOVED OVERNIGHT SINCE IT LOOKS LIKE
FORCING WILL STAY WELL WEST OF THOSE AREAS. SCHULTZ
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
THE BIG MESSAGE FOR THE EARLY PART OF THE EXTENDED IS PERSISTENT
SNOW FOR AREA MOUNTAINS INTO WEDNESDAY. FROM FRIDAY NIGHT THROUGH
WEDNESDAY SOME WEST FACING SLOPES OF THE BEARTOOTH AND CRAZY
MOUNTAINS COULD SEE OVER 2 FEET OF SNOW.
ZONAL PACIFIC FLOW OVER THE AREA ON MONDAY WILL BRING ENOUGH
MOISTURE TO INCREASE POPS EVEN IN LOWER ELEVATIONS DESPITE
DOWNSLOPE WINDS. THIS SHOULD BRING A SHOT OF 3 TO 6 INCHES OF SNOW
TO WEST FACING MOUNTAIN SLOPES. THIS FLOW CONTINUES ON TUESDAY
WITH SIMILAR MOUNTAIN SNOW ACCUMULATIONS. SNOW ACCUMULATIONS FOR
THE LOWER ELEVATIONS WILL LIKELY BE CONFINED TO FOOTHILLS AND
VALLEYS ADJACENT TO AREA MOUNTAINS MONDAY AND TUESDAY. A PACIFIC
SYSTEM MOVING INTO CALIFORNIA WILL DEFLECT THE FLOW TO THE
NORTHWEST OVER THE AREA CUTTING OFF STRONGEST PACIFIC MOISTURE
FETCH BY LATE WEDNESDAY AND ENDING BEST PRECIPITATION CHANCES.
RIDGING DEVELOPS ALOFT THURSDAY INTO THE WEEKEND...BUT RIDGE AXIS
STAYS WEST OF THE AREA UNTIL SATURDAY WHICH WILL KEEP COOL
NORTHWESTERLY FLOW OVER THE AREA AND KEEP THE POSSIBILITY OF
BACKDOOR TYPE FRONTS IN PLAY FOR THE FORECAST AREA. CHAMBERS
&&
.AVIATION...
AREAS OF SNOW WILL CONTINUE THROUGH THE NIGHT MAINLY ALONG AND
WEST OF A SHERIDAN-BILLINGS-ROUNDUP LINE. THIS WILL RESULT IN
MAINLY IFR CONDITIONS THROUGH THE NIGHT AND INTO THE MID MORNING
HOURS SATURDAY. ELSEWHERE ACROSS THE LOWER ELEVATIONS...EXPECT
SCATTERED SNOW SHOWERS AND MVFR CONDITIONS. OTHERWISE...VFR
CONDITIONS WILL PREVAIL. IN ADDITION...SOME PATCHY FOG WILL BE
POSSIBLE FROM HYSHAM TO MILES CITY THROUGH ABOUT 09Z SATURDAY. THE
MOUNTAINS WILL BE OBSCURED WITH SNOW SHOWERS. HOOLEY
&&
.PRELIMINARY POINT TEMP/POPS...
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 026/034 022/034 021/037 025/037 021/028 013/029 018/031
76/J 02/J 21/N 22/J 31/B 00/B 11/B
LVM 022/032 019/031 018/033 025/032 017/023 010/027 018/029
+6/J 14/J 43/J 23/J 32/J 00/B 21/B
HDN 020/034 017/034 018/038 023/038 020/030 012/030 017/032
56/J 02/J 21/B 22/J 31/B 00/B 11/B
MLS 020/031 017/032 017/034 020/037 021/031 011/028 011/031
32/J 02/J 21/B 11/B 21/B 01/B 11/B
4BQ 018/032 016/033 015/037 021/037 021/032 013/031 015/034
13/J 02/J 21/B 11/B 21/B 01/B 11/B
BHK 016/030 013/031 015/033 017/036 021/030 012/026 009/030
12/J 12/J 21/B 11/B 21/B 01/B 11/B
SHR 020/031 017/032 017/038 021/036 019/028 012/029 016/036
54/J 13/J 21/B 12/J 22/J 00/B 11/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BILLINGS MT
916 PM MST FRI DEC 14 2012
.SHORT TERM...VALID FOR SAT AND SUN...
RADAR IMAGERY AT MID EVENING SHOWS SNOW EXTENDING FROM LIVINGSTON
AND BIG TIMBER NORTHEAST TO HARLOWTON AND RYEGATE...WHERE THERE/S
A BIT OF ENHANCEMENT IN REFLECTIVITY. A MODEST...BUT WELL-DEFINED
AREA OF FRONTOGENESIS IN THE 850-700 HPA LAYER IS LIKELY THE MAIN
FORCING FOR THIS PRECIPITATION IN ADVANCE OF A 500-HPA SHORT WAVE
TROUGH. THE 00 UTC GFS...00 UTC NAM...AND 21 UTC SREF ALL SEEM TO
HAVE A GOOD HANDLE ON THIS...AND PRODUCE ENOUGH QPF FOR PRIMARILY
ONE TO THREE INCHES OF SNOW IN SOUTH CENTRAL MT TONIGHT. BASED ON
RECENT OBSERVATIONAL TRENDS AND THAT MODEL SUPPORT...WE INCREASED
POPS TO BETWEEN 80 AND 100 PERCENT IN SOUTH CENTRAL MT OVERNIGHT.
VISIBILITY IN THE SNOWFALL HAS MAINLY BEEN FROM 1 TO 3 MILES THIS
EVENING...IMPLYING SNOWFALL RATES THAT AREN/T QUITE ENOUGH FOR US
TO NEED AN ADVISORY. HOWEVER...THAT WILL REQUIRE CLOSE MONITORING
GIVEN PERSISTENT FORCING AND INSTABILITY NOTED BY STEEP MID-LEVEL
LAPSE RATES. THE 02 AND 03 UTC RAP RUNS BOTH DO WELL WITH ONGOING
SNOW...AND TAKE LIGHT SNOW INTO BILLINGS BETWEEN 06 AND 09 UTC...
SO LIKELY POPS STILL GOOD THERE AS WELL.
IN SOUTHEASTERN MT...WE REMOVED MOST OF THE FOG MENTION SINCE THE
INCREASE IN CLOUDS SHOULD PREVENT ITS FORMATION...EXPECT MAYBE IN
THE YELLOWSTONE RIVER VALLEY FROM FORSYTH TO MILES CITY. POPS FOR
BAKER AND EKALAKA WERE ALSO REMOVED OVERNIGHT SINCE IT LOOKS LIKE
FORCING WILL STAY WELL WEST OF THOSE AREAS. SCHULTZ
.LONG TERM...VALID FOR MON...TUE...WED...THU...FRI...
THE BIG MESSAGE FOR THE EARLY PART OF THE EXTENDED IS PERSISTENT
SNOW FOR AREA MOUNTAINS INTO WEDNESDAY. FROM FRIDAY NIGHT THROUGH
WEDNESDAY SOME WEST FACING SLOPES OF THE BEARTOOTH AND CRAZY
MOUNTAINS COULD SEE OVER 2 FEET OF SNOW.
ZONAL PACIFIC FLOW OVER THE AREA ON MONDAY WILL BRING ENOUGH
MOISTURE TO INCREASE POPS EVEN IN LOWER ELEVATIONS DESPITE
DOWNSLOPE WINDS. THIS SHOULD BRING A SHOT OF 3 TO 6 INCHES OF SNOW
TO WEST FACING MOUNTAIN SLOPES. THIS FLOW CONTINUES ON TUESDAY
WITH SIMILAR MOUNTAIN SNOW ACCUMULATIONS. SNOW ACCUMULATIONS FOR
THE LOWER ELEVATIONS WILL LIKELY BE CONFINED TO FOOTHILLS AND
VALLEYS ADJACENT TO AREA MOUNTAINS MONDAY AND TUESDAY. A PACIFIC
SYSTEM MOVING INTO CALIFORNIA WILL DEFLECT THE FLOW TO THE
NORTHWEST OVER THE AREA CUTTING OFF STRONGEST PACIFIC MOISTURE
FETCH BY LATE WEDNESDAY AND ENDING BEST PRECIPITATION CHANCES.
RIDGING DEVELOPS ALOFT THURSDAY INTO THE WEEKEND...BUT RIDGE AXIS
STAYS WEST OF THE AREA UNTIL SATURDAY WHICH WILL KEEP COOL
NORTHWESTERLY FLOW OVER THE AREA AND KEEP THE POSSIBILITY OF
BACKDOOR TYPE FRONTS IN PLAY FOR THE FORECAST AREA. CHAMBERS
&&
.AVIATION...
FOG MAY IMPACT KMLS TONIGHT THROUGH SATURDAY MORNING.
PRECIPITATION WILL DEVELOP IN THE KLVM VICINITY THIS EVENING AND
SPREAD EAST TO KBIL AND KSHR OVERNIGHT THROUGH SATURDAY MORNING.
EXPECT PERIODS OF MVFR/IFR CONDITIONS. BRS
&&
.PRELIMINARY POINT TEMP/POPS...
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 026/034 022/034 021/037 025/037 021/028 013/029 018/031
76/J 02/J 21/N 22/J 31/B 00/B 11/B
LVM 022/032 019/031 018/033 025/032 017/023 010/027 018/029
+6/J 14/J 43/J 23/J 32/J 00/B 21/B
HDN 020/034 017/034 018/038 023/038 020/030 012/030 017/032
56/J 02/J 21/B 22/J 31/B 00/B 11/B
MLS 020/031 017/032 017/034 020/037 021/031 011/028 011/031
32/J 02/J 21/B 11/B 21/B 01/B 11/B
4BQ 018/032 016/033 015/037 021/037 021/032 013/031 015/034
13/J 02/J 21/B 11/B 21/B 01/B 11/B
BHK 016/030 013/031 015/033 017/036 021/030 012/026 009/030
12/J 12/J 21/B 11/B 21/B 01/B 11/B
SHR 020/031 017/032 017/038 021/036 019/028 012/029 016/036
54/J 13/J 21/B 12/J 22/J 00/B 11/B
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
WY...NONE.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
345 AM CST SAT DEC 15 2012
.SHORT TERM...THROUGH 12Z TUESDAY. EVENING UPPER AIR ANALYSIS
INDICATES A MID LEVEL LOW OVER SOUTHWESTERN KANSAS...WITH
SOUTHWESTERLY TO QUASI-ZONAL MID AND UPPER LEVEL FLOW PERSISTING
ACROSS MUCH OF THE REST OF THE CONUS. MID AND UPPER LEVEL JET
ENERGY EXTENDS FROM TEXAS...NORTHEAST INTO THE MID-MISSISSIPPI
VALLEY AND THEN EAST/SOUTHEAST INTO THE EASTERN CONUS. WITH THE
BULK OF THE JET ENERGY REMAINING SOUTH AND EAST OF THE CENTRAL
PLAINS...MID TO UPPER LEVEL TROPOSPHERIC FLOW IS NOT OVERLY
IMPRESSIVE OVER OUR AREA...MAXING OUT AT AROUND 70KTS NEAR 200MB
PER 00Z SOUNDING DATA FROM KLBF. WATER VAPOR IMAGERY ALSO SHOWS
THE MID LEVEL LOW OVER SOUTHWESTERN KANSAS...MOVING NORTHEAST.
INCREASED MID LEVEL MOISTURE IS NOTED EXTENDING FROM SOUTHERN
TEXAS INTO THE LOWER MISSISSIPPI VALLEY...WITH A MID LEVEL DRY
INTRUSION EXTENDING FROM NORTH TEXAS INTO EASTERN KANSAS. MID
LEVEL DEFORMATION TO THE NORTH/NORTHWEST OF THE MID LEVEL LOW IS
APPARENT OVER PORTIONS OF NEBRASKA AND KANSAS. AT THE SURFACE AN
AREA OF LOW PRESSURE IS NOTED OVER CENTRAL KANSAS...WITH A WARM
FRONT EXTENDING NORTHEAST FROM THE LOW ACROSS NORTH CENTRAL KANSAS
AND SOUTH CENTRAL NEBRASKA. THE LOW LEVEL WIND FIELD ACROSS THE
SOUTHEASTERN HALF OF OUR CWA...WITHIN THE WARM SECTOR OF THIS
SYSTEM...REMAINS FROM THE SOUTHEAST...WITH LOCATIONS FARTHER
NORTHWEST ACROSS THE AREA REPORTING SURFACE WINDS FROM THE NORTH.
RADAR RETURNS FROM KUEX...AS WELL AS GUIDANCE FROM THE RAP AND
NAM...SUGGEST THE PRIMARY AXIS OF MID LEVEL DEFORMATION WILL
CONTINUE PUSHING EAST/NORTHEAST...AWAY FROM OUR AREA THROUGH THE
REST OF TODAY. THE RESULTANT PRECIPITATION SHIELD SHOULD ALSO
CONTINUE MOVING OUT OF THE AREA THIS MORNING...WITH PRECIPITATION
EXPECTED TO BE DONE BY NO LATER THAN 18Z. AS A RESULT...WENT AHEAD
AND CARRIED SLIGHT CHANCE TO CHANCE POPS ACROSS OUR NORTHEAST
12-18Z...WITH DRY CONDITIONS THEREAFTER.
GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL
SUGGEST QUASI-ZONAL MID AND UPPER LEVEL FLOW WILL BE OBSERVED
ACROSS MUCH OF THE CONUS TONIGHT THROUGH MONDAY NIGHT...WITH
MULTIPLE SMALL-SCALE MID LEVEL PERTURBATIONS ADVANCING WITHIN THE
MEAN FLOW OVER THE CENTRAL PLAINS. QPF FIELDS FROM THESE MODELS
ALL SUGGEST LIGHT PRECIPITATION WILL BE POSSIBLE OVER VARIOUS
POINTS ACROSS THE CWA IN ASSOCIATION WITH THESE MID LEVEL
PERTURBATIONS. UNFORTUNATELY LITTLE TO NO MODEL AGREEMENT EXISTS
WITH RESPECT TO WHEN AND WHERE THIS LIGHT PRECIPITATION WILL BE
REALIZED. SO...ALTHOUGH PERIODIC LIGHT PRECIPITATION IS CERTAINLY
WITHIN THE REALM OF POSSIBILITIES THROUGH THE NEXT COUPLE DAYS...A
LACK IN CONFIDENCE WITH RESPECT TO PRECIPITATION TIMING AND
PLACEMENT PREVENTS THE INTRODUCTION OF POPS TO THE FORECAST FOR
TONIGHT THROUGH MONDAY NIGHT.
THE SURFACE LOW...CURRENTLY MOVING ACROSS KANSAS...IS EXPECTED TO
CONTINUE DOING SO TODAY...THUS ALLOWING THE LOW LEVEL WIND FIELD
ACROSS OUR AREA TO BECOME MORE NORTHWESTERLY. DESPITE THIS CHANGE
IN WIND DIRECTION...LOW LEVEL COLD AIR ADVECTION IS NOT EXPECTED
TO BE PARTICULARLY STRONG. DECENT DIABATIC HEATING SHOULD BE
REALIZED TODAY...ESPECIALLY ACROSS OUR SOUTHWEST...AS THE CLOUDS
CLEAR FROM SOUTHWEST TO NORTHEAST AND AS A RESULT...AFTERNOON
HIGHS IN THE 40S TO LOW 50S CERTAINLY SEEM REASONABLE. SOME
INCREASE IN MID TO HIGH LEVEL CLOUDS WILL PROBABLY BE REALIZED
TONIGHT AS THE FIRST IN THE SERIES OF AFOREMENTIONED MID LEVEL
PERTURBATIONS PUSHES OVERHEAD AND GIVEN THIS EXPECTED INCREASE IN
CLOUD COVER...OVERNIGHT TEMPERATURE DROP-OFFS OF 20-25 DEGREES
SEEMS REASONABLE WHICH PRESENTS LOWS GENERALLY IN THE 20S. THE
PASSAGE OF THE MID LEVEL PERTURBATIONS SHOULD ALSO PROMOTE A
SUBTLE INCREASE IN LOW LEVEL COLD AIR ADVECTION...THUS PRESENTING
SLIGHTLY COOLER WEATHER TO FINISH OUT THE SHORT TERM FORECAST
PERIOD. HIGHS IN THE 30S AND 40S ARE CURRENTLY FORECAST BOTH
SUNDAY AND MONDAY AS A RESULT.
.LONG TERM...(TUESDAY THROUGH FRIDAY) THE MAIN STORY: BRIEFLY MILD
TUE BEFORE A TRANSITION TO NEAR-NORMAL COLD AND A POTENTIAL
OPPORTUNITY FOR SNOW MID-WEEK.
PATTERN: THE HEMISPHERIC HGT PATTERN WILL CHANGE LITTLE THRU
CHRISTMAS PER CPC ENSEMBLE MULTI-DAY MEANS. THE NAO AND PNA WILL
BOTH REMAIN NEGATIVE...FAVORING TROFS ALONG THE PAC/ATLANTIC
COASTS AND RIDGING OVER THE PLAINS. WE ARE LIKELY TO SEE ONE MORE
POTENT PAC-ORIGIN TROF THE MIDDLE OF NEXT WEEK BEFORE THE BLOCKING
DEVELOPS IN THE LONGWAVE PATTERN AFTER DEC 22. WE`VE NOTED THE
INCREASING HGTS OVER THE ROCKIES IN THE GFS/EC 5-DAY MEANS THE
WEEK OF CHRISTMAS.
TEMPS WILL BE MUCH ABOVE NORMAL TUE AND THEN IT LOOKS LIKE NEAR
NORMAL TEMPS /SUBSTANTIALLY COLDER THAN WE`VE EXPERIENCE THIS MILD
NOV-DEC/ WED-FRI. NO SUBSTANTIAL/BELOW NORMAL COLD IS FORESEEN
THRU CHRISTMAS...BUT THE PATTERN DOES SUGGEST WE FLIRT MORE WITH
SEASONABLE/NEAR-NORMAL TEMPS OVER THE NEXT 10 DAYS. THIS IS
ESPECIALLY TRUE IF LOW PRES ENDS UP BLOCKED OVER ERN CANADA AND
THE CNTRL USA LONGWAVE RIDGE RETROGRADES TO THE ROCKIES AND
AMPLIFIES DOWNSTREAM OF A CUT-OFF LOW FCST OVER THE E PACIFIC.
THIS HGT PATTERN SUGGESTS WE MIGHT SEE PNA EVENTUALLY TURN
POSITIVE TO ACT IN CONCERT WITH THE -NAO.
HAZARDS: WE`RE SEEING A BURGEONING SIGNAL FOR SOME SNOW LATE WED
INTO WED NGT. TOO EARLY TO TELL THE MAGNITUDE BUT THE SLP/H5
HEIGHTS LOOK THREATENING. WHILE IT APPEARS WINTER HEADLINES ARE
CURRENTLY A LOW PROBABILITY...BELIEVE IT/S WORTHY OF INCLUSION IN
THE HWO BECAUSE THE POTENTIAL IS THERE.
PCPN: PROBABILITIES ARE INCREASING FOR A LGT-MDT EVENT WED-WED
NGT.
THE DAILY DETAILS...
TUE: THE WEAK LOW THE 00Z/14 EC HAD /THAT I DISMISSED 24 HRS AGO/
HAS NOW BEEN JOINED BY A HOST OF OTHER 12Z/14 AND 00Z/15 MODELS.
SO IT LOOKS LIKE A WEAK LOW WILL SLIDE DOWN THE DEVELOPING WARM
FRONT ...SHUNTING IT TO OUR S AS IT HEADS E. OVERALL STILL LOOKING
LIKE A NICE DAY...PROBABLY THE PICK OF THE WEEK WITH HIGH TEMPS
10-15F ABOVE NORMAL.
WED-THU: LOOKING SUBSTANTIALLY MORE INTERESTING THAN 24 HRS AGO
WITH THIS TIME FRAME NOW THREATENING SOME MEASURABLE
SNOWFALL...LOOKING ONLY AT SFC PRES AND H5 HEIGHTS. IT/S NOT IN
THE BAG YET BUT THIS COULD SPELL TROUBLE FOR ALL OR PART OF THE
FCST AREA. EVEN PWAT/S ARE FCST HIGHER WITH THE GFS ENSEMBLE MEAN
NOW DRAWING +1 STANDARD DEVIATION PWAT ALL THE WAY UP TO NEB.
THIS SYSTEM MOVED OFF JAPAN FRI AND IS CURRENTLY NEAR THE DATELINE
/SW OF THE ALEUTIANS/ IN WV IMAGERY. THIS TROF WILL TOP THE PAC
SUB-TROPICAL HIGH AND AMPLIFY AS IT MOVES INTO THE LONGWAVE TROF
ALONG THE W COAST. GEM/GFS/EC/UKMET ARE IN UNISON ON SHORTENING
ITS WAVELENGTH VS 24 HRS AGO.
THE GFS AND ITS ENSEMBLE MEMBERS SEEM WAYYY TOO FAR N WITH THEIR
MAX AXIS OF QPF DESPITE ITS SFC LOWS CLOSE TO THE EC. THE 00Z/15
IS THE FIRST EC RUN THAT THREATENS WARNING CRITERIA QPF AND IT HAS
EXCELLENT SLP/H5 SUPPORT FROM ITS ENSEMBLE MEAN.
TEMPS: WED NGT AND THU NGT PUSHED LOW TEMPS DOWN TO BIAS CORRECTED
ALL-BLEND GUIDANCE...IN CONCERT WITH LBF. AND MAY NOT BE LOW
ENOUGH THU NGT IF SNOW COVER MATERIALIZES. IDEAL RADIATING CONDS
UNDER HIGH PRES SUGGEST TEMPS MAY END UP ANOTHER 5-10F COLDER.
WINDS WERE INCREASED ABOVE GUIDANCE WED AFTN-THU AFTN.
THU CLEARING AND COLDER AND THIS NEAR-NORMAL COLD PROBABLY LINGERS
INTO FRI AS THE DEPARTING LOW CUTS OFF OVER THE NE USA.
&&
.CLIMATE...GRI HAS FINALLY EXCEEDED 10 INCHES FOR THE YEAR WITH
THIS RAINFALL EVENT. HOWEVER...WITH THE DRIEST YEAR ON RECORD AT
12.01 /1940/...ODDS STILL FAVOR 2012 ENDING UP THE NEW DRIEST YEAR
ON RECORD. PRECIP RECORDS DATE BACK TO 1895 AT GRAND ISLAND.
&&
PREV DISCUSSION... /ISSUED 1120 PM CST FRI DEC 14 2012/
AVIATION...06Z KGRI TAF. PREVAILING MVFR CONDITIONS EXPECTED
THROUGH 01Z SUNDAY...WITH TEMPORARY IFR CONDITIONS ALSO FORECAST
THROUGH 14Z SATURDAY. A MID LEVEL LOW...CURRENTLY OVER
SOUTHWESTERN KANSAS...IS PROMOTING A BAND OF DEFORMATION OVER
SOUTH CENTRAL NEBRASKA...THUS RESULTING IN A STRATUS SHIELD WITH
CEILINGS GENERALLY IN THE 500-1000FT AGL RANGE ACROSS THE REGION.
THESE LOW CEILINGS CAN BE EXPECTED AT THE TERMINAL THROUGH MUCH OF
THE TAF PERIOD...WITH IMPROVING CONDITIONS EXPECTED LATE SATURDAY
AFTERNOON OR EVENING AS THE PRIMARY BAND OF DEFORMATION...AND
RESULTANT STRATUS...PUSHES TO THE EAST/NORTHEAST OF THE TERMINAL.
MVFR...AND PERHAPS IFR...VISIBILITY RESTRICTIONS IN -RA AND BR
WILL ALSO BE POSSIBLE AT THE TERMINAL THROUGH MID TO LATE MORNING
SATURDAY. THE SURFACE WIND WILL REMAIN FROM THE SOUTHEAST THROUGH
TONIGHT...BECOMING LIGHT AND VARIABLE BY 10Z...AND THEN BECOMING
ESTABLISHED FROM THE NORTHWEST BY NO LATER THAN MID-MORNING
SATURDAY.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM/AVIATION...BRYANT
LONG TERM/CLIMATE...HALBLAUB
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1256 AM CST SAT DEC 15 2012
.UPDATE...EVENING UPPER AIR ANALYSIS INDICATES A MID LEVEL LOW
OVER SOUTHWESTERN KANSAS...WITH SOUTHWESTERLY TO QUASI-ZONAL MID
AND UPPER LEVEL FLOW PERSISTING ACROSS MUCH OF THE REST OF THE
CONUS. MID AND UPPER LEVEL JET ENERGY EXTENDS FROM
TEXAS...NORTHEAST INTO THE MID-MISSISSIPPI VALLEY AND THEN
EAST/SOUTHEAST ACROSS THE EASTERN CONUS. WITH THE BULK OF THE JET
ENERGY REMAINING SOUTH AND EAST OF THE CENTRAL PLAINS...MID TO
UPPER LEVEL TROPOSPHERIC FLOW IS NOT OVERLY IMPRESSIVE OVER OUR
AREA...MAXING OUT AT AROUND 70KTS NEAR 200MB PER 00Z SOUNDING DATA
FROM KLBF. WATER VAPOR IMAGERY ALSO SHOWS THE MID LEVEL LOW OVER
SOUTHWESTERN KANSAS...MOVING NORTHEAST. INCREASED MID LEVEL
MOISTURE IS NOTED EXTENDING FROM SOUTHERN TEXAS INTO THE LOWER
MISSISSIPPI VALLEY...WITH A MID LEVEL DRY INTRUSION EXTENDING FROM
NORTH TEXAS INTO EASTERN KANSAS. MID LEVEL DEFORMATION TO THE
NORTH/NORTHWEST OF THE MID LEVEL LOW IS APPARENT OVER MUCH OF
NEBRASKA AND WESTERN KANSAS. AT THE SURFACE AN AREA OF LOW
PRESSURE IS NOTED OVER WESTERN KANSAS...WITH A WARM FRONT
EXTENDING NORTHEAST FROM THE LOW ACROSS NORTH CENTRAL KANSAS AND
SOUTH CENTRAL NEBRASKA. THE LOW LEVEL WIND FIELD ACROSS THE
SOUTHEASTERN HALF OF OUR CWA...WITHIN THE WARM SECTOR OF THIS
SYSTEM...REMAINS FROM THE SOUTHEAST...WITH LOCATIONS FARTHER
NORTHWEST ACROSS THE AREA REPORTING SURFACE WINDS FROM THE NORTH.
THUS FAR THE STORM SYSTEM IS UNFOLDING AS EXPECTED. THE PRIMARY
AXIS OF MID LEVEL THERMAL ADVECTION HAS PUSHED TO THE EAST OF OUR
AREA...WITH THE EXTREME NORTHWESTERN PERIPHERY OF THE MID LEVEL
DRY INTRUSION TRYING TO WORK INTO EXTREME SOUTHEASTERN PORTIONS OF
OUR CWA. FARTHER NORTHWEST HOWEVER...ACROSS MOST OF THE REST OF
OUR CWA...PRECIPITATION CONTINUES AS THE PRIMARY AXIS OF MID LEVEL
DEFORMATION PERSISTS OVER THE AREA. SURFACE OBSERVATIONS...AS WELL
AS PROXIMITY SOUNDINGS FROM ACROSS THE CWA PER RAP AND LAPS
DATA...INDICATE THE LOWER TROPOSPHERE REMAINS TOO WARM FOR SNOW
PRODUCTION...THUS RAIN HAS BEEN REPORTED WITH THIS SYSTEM THUS
FAR. WITH SURFACE DEWPOINTS RANGING FROM 36 AT KLXN...TO 35 AT
KBBW...TO 38 KODX...AND WELL INTO THE 40S FARTHER SOUTHEAST...FIND
IT HARD TO BELIEVE THE LOW LEVEL AIRMASS WILL ALLOW SUBSTANTIAL
SNOWFALL TO DEVELOP ACROSS OUR AREA THROUGH THE REST OF TONIGHT
AND INTO SATURDAY MORNING. DRIER AND COOLER LOW LEVEL AIR MAY
PRESENT ITSELF TO NORTHERN PORTIONS OF OUR CWA AFTER SUNRISE...BUT
BY THEN PRECIPITATION SHOULD BE TAPERING OFF AS THE PRIMARY AXIS
OF MID LEVEL DEFORMATION PUSHES EAST/NORTHEAST OF OUR AREA. GIVEN
ALL THIS...FEEL CONFIDENT IN KEEPING THE FORECAST AS IS.
GIVEN THE CURRENT RADAR RETURNS FROM KUEX...AS WELL AS SHORT TERM
GUIDANCE FROM THE RAP AND NAM...WILL KEEP THE 100% POPS GOING FOR
PORTIONS OF OUR AREA CURRENTLY UNDERNEATH THE DEFORMATION
AXIS...WITH POPS DIMINISHING AFTER 12Z SATURDAY. NO SNOWFALL
ACCUMULATION IS CURRENTLY FORECAST. DEEP LAYER MUCAPE VALUES...PER
RAP DATA...HAVE ALSO DROPPED OFF TO NEAR-ZERO AND AS A
RESULT...WENT AHEAD AND REMOVED ANY THUNDER MENTION FROM THE HWO.
TWEAKED HOURLY TEMP AND DEWPOINT GRIDS TO BETTER REFLECT CURRENT
CONDITIONS BUT AGAIN...OVERALL THE FORECAST REMAINS IN GREAT
SHAPE.
&&
.PREV DISCUSSION... /ISSUED 1120 PM CST FRI DEC 14 2012/
AVIATION...06Z KGRI TAF. PREVAILING MVFR CONDITIONS EXPECTED
THROUGH 01Z SUNDAY...WITH TEMPORARY IFR CONDITIONS ALSO FORECAST
THROUGH 14Z SATURDAY. A MID LEVEL LOW...CURRENTLY OVER
SOUTHWESTERN KANSAS...IS PROMOTING A BAND OF DEFORMATION OVER
SOUTH CENTRAL NEBRASKA...THUS RESULTING IN A STRATUS SHIELD WITH
CEILINGS GENERALLY IN THE 500-1000FT AGL RANGE ACROSS THE REGION.
THESE LOW CEILINGS CAN BE EXPECTED AT THE TERMINAL THROUGH MUCH OF
THE TAF PERIOD...WITH IMPROVING CONDITIONS EXPECTED LATE SATURDAY
AFTERNOON OR EVENING AS THE PRIMARY BAND OF DEFORMATION...AND
RESULTANT STRATUS...PUSHES TO THE EAST/NORTHEAST OF THE TERMINAL.
MVFR...AND PERHAPS IFR...VISIBILITY RESTRICTIONS IN -RA AND BR
WILL ALSO BE POSSIBLE AT THE TERMINAL THROUGH MID TO LATE MORNING
SATURDAY. THE SURFACE WIND WILL REMAIN FROM THE SOUTHEAST THROUGH
TONIGHT...BECOMING LIGHT AND VARIABLE BY 10Z...AND THEN BECOMING
ESTABLISHED FROM THE NORTHWEST BY NO LATER THAN MID-MORNING
SATURDAY.
PREV DISCUSSION... /ISSUED 954 PM CST FRI DEC 14 2012/
UPDATE...FORECAST IS ON TRACK. RAIN SHOWERS CONTINUE TO MOVE NORTH
OUT OF KANSAS INTO NEBRASKA IN BANDS. AS EXPECTED...MOST OF THE
RAIN WILL FALL OVER THE NEXT FEW HOURS AND PRETTY MUCH BE OUT OF
HERE BY DAWN.
PREV DISCUSSION... /ISSUED 349 PM CST FRI DEC 14 2012/
SHORT TERM...TONIGHT AND TOMORROW. PRIMARY FORECAST CONCERN LIES
WITH PRECIPITATION CHANCES.
REALLY HASNT BEEN ANY NOTABLE CHANGES WITH THE LATEST MODELS...AND
THINGS ARE AT LEAST SO FAR GOING PRETTY MUCH AS EXPECTED. UPPER
LEVEL SATELLITE DATA SHOWING THE LOW PRESSURE SYSTEM OF INTEREST
SWINGING THROUGH THE FOUR CORNERS REGION...WHILE OUT AHEAD
MOISTURE AND WARMER AIR CONTINUE TO STREAM IN FROM THE SOUTH.
CLOUD COVER HAS BEEN ON THE INCREASE THROUGH THE DAY...AND AS
SURFACE LOW PRESSURE BETTER ORGANIZES ACROSS EASTERN COLORADO
WINDS HAVE BECOME MORE SOUTHERLY AND INCREASED IN SPEED...ESP
ERN/SRN LOCATIONS. AFTER STARTING THE DAY OFF WITH LOWS IN THE
SINGLE DIGITS/TEENS...TEMPERATURES THIS AFTERNOON HAVE CLIMBED
INTO THE LOWER 40S IN THE NORTH TO NEAR 60 IN THE FAR SOUTHEAST.
THE MAIN PERIOD OF PRECIPITATION STILL ON TAP FOR THE 00Z-12Z
PERIOD TONIGHT...AND OUTSIDE OF MAKING TIMING ADJUSTMENTS...NO
SIGNIFICANT CHANGES WERE MADE TO THE POPS. POST 06Z...DID START TO
TREND BACK THE SW CORNER OF THE CWA MORE...THE BETTER CHANCES WILL
GRADUALLY BE SHIFTING NORTHEAST AS THE UPPER LEVEL LOW SLIDES
ACROSS THE PLAINS AND DRIER MID/UPPER LEVEL AIR BUILDS IN FROM THE
SOUTHWEST. WILL CONTINUE THE LINGERING LOWER POPS DURING THE
MORNING HOURS...AND ALSO DECIDED TO INSERT A MENTION OF SPRINKLES
ACROSS THE EAST DURING THE AFTERNOON...AN AREA WHICH WILL REMAIN
UNDER GREATER INFLUENCE OF ENERGY/MOISTURE WRAPPING AROUND THE
BACKSIDE OF THE MAIN UPPER LEVEL LOW.
AT THE SURFACE...AGAIN NOT MANY CHANGES WERE MADE...MODELS REMAIN
IN PRETTY GOOD AGREEMENT KEEPING THE SOUTH/SOUTHEASTERLY WINDS IN
PLACE CWA-WIDE THROUGH THE EVENING HOURS. NEAR/POST 06Z...THE
SURFACE COLD FRONT WILL BEGIN TO ENTER THE WRN CWA...WITH MODEL
TIMING SHOWING THE FRONT ROUGHLY JUST WEST OF HW 281 BY 09Z....AND
NEAR HW 81 BY 12Z. WILL SEE A BREEZY DAY ON SATURDAY...AS THE CWA
SITS IN A TIGHTENED PRESSURE GRADIENT BETWEEN THE DEPARTING LOW
AND HIGHER PRESSURE SLIDING IN FROM THE NORTHWEST...STILL LOOKING
AT SPEEDS NEAR 15 TO 20 MPH...DIMINISHING AS WE APPROACH EVENING.
STILL EXPECTING A LIQUID PRECIPITATION TYPE EVENT...WITH MODELS
REMAINING IN GOOD AGREEMENT KEEPING TEMPS AT THE SFC AND ALOFT
ABOVE FREEZING. JUST NOT A GOOD PUSH OF COLDER AIR WITH THIS
SYSTEM...AND IF TEMPS ALOFT WERE LOOKING TO BE BELOW 0 AND SFC
TEMPS WERE NEAR/BELOW 35 OR SO...WOULD BE MORE CONCERNED ABT
SNOW/ACCUMULATIONS...BUT NONE OF THE MODELS ARE SHOWING THAT. AS
FAR AS PRECIPITATION TOTALS GO...COULD END UP SEEING QUITE A RANGE
BY THE TIME ITS ALL SAID AND DONE...AND MODELS CONTINUE TO VARY
WITH WHERE THE BAND OF HIGHER TOTALS END UP. SOME LOCATIONS MAY BE
LOOKING AT A TENTH OF AN INCH...OTHERS APPROACHING OR POSSIBLY
EXCEEDING THREE QUARTERS OF AN INCH /THOSE WOULD LIKELY BE PRETTY
LOCALIZED SPOTS/.
LONG TERM...STARTING SATURDAY NIGHT...A FAIRLY ZONAL AND
PROGRESSIVE UPPER LEVEL PATTERN IS EXPECTED TO PERSIST THROUGH
MUCH OF NEXT WEEK...BEFORE A BROAD RIDGE OF HIGH PRESSURE IS
FORECAST TO BUILD ACROSS THE INTERMOUNTAIN WEST BY THE END OF THE
WEEK.
EXPECT THE UPPER LEVEL LOW OFF THE CENTRAL CALIFORNIA COAST THIS
AFTERNOON TO CROSS THE SOUTHERN ROCKIES AND EJECT INTO THE CENTRAL
PLAINS SATURDAY EVENING...WHICH MAY PROVIDE JUST ENOUGH FORCING
FOR A FEW SNOW FLURRIES OVERNIGHT SATURDAY INTO EARLY SUNDAY
MORNING. HOWEVER...WITH THE LOW LEVELS OF THE ATMOSPHERE BEGINNING
TO DRY OUT BEHIND THIS EVENINGS LOW...DID NOT HAVE THE CONFIDENCE
TO INTRODUCE A CHANCE FOR MEASURABLE PRECIP AT THIS TIME DESPITE
SOME OF THE MODEL GUIDANCE ATTEMPTING TO GENERATE A FEW HUNDREDTHS
OF ON INCH OF PRECIPITATION. OTHERWISE...MAINTAINED A DRY FORECAST
TO FINISH OFF THE WEEKEND AND START OFF THE NEW WORK WEEK...AS
ALTHOUGH THERE WILL BE A PAIR OF WEAK UPPER LEVEL DISTURBANCES
PASSING BY TO THE NORTH...LITTLE APPRECIABLE IMPACTS ARE EXPECTED
LOCALLY.
BY NEXT WEDNESDAY...MODELS ARE IN FAIRLY GOOD AGREEMENT
PROGRESSING A COLD FRONT ACROSS THE AREA IN CONCERT WITH THE NEXT
UPPER LEVEL LOW CROSSING THE ROCKIES...WHICH WILL LIKELY PROVIDE
THE NEXT BEST CHANCE FOR SOME MEASURABLE PRECIP ACROSS THE REGION.
KEPT CHANCES FOR MEASURABLE PRECIP FAIRLY LOW WITH THE PASSAGE OF
THIS FRONT OVERNIGHT WEDNESDAY INTO THURSDAY MORNING AT THIS
TIME...ALBEIT BOTH THE GFS AND EC ARE POINTING TO AT LEAST A LIGHT
PRECIPITATION EVENT ACROSS THE LOCAL AREA. IF THE PRECIPITATION
DOES COME TO FRUITION...EXPECT A LIGHT DUSTING OF SNOW OVERNIGHT
WEDNESDAY...AS TEMPERATURES ALOFT ARE EXPECTED TO DROP 10-15C WITH
THE PASSAGE OF THIS FRONT...FULLY SUPPORTING SNOW. TEMPERATURES
THROUGH THE EXTENDED PERIODS ARE EXPECTED TO RUN NEAR OR SLIGHTLY
ABOVE CLIMO EACH DAY...WITH AFTERNOON TEMPERATURES PEAKING TUESDAY
NEAR 50 DEGREES...AS A DOWNSLOPING WESTERLY FLOW WILL LIKELY MAKE
THIS THE WARMEST DAY OF THE EXTENDED.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
1256 AM UPDATE/AVIATION...BRYANT
SHORT TERM...ADO
LONG TERM...ROSSI
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1143 PM CST FRI DEC 14 2012
.AVIATION...
AREAS OF LIGHT RAIN WILL SPREAD TO THE NORTHEAST OVER WESTERN
NEBRASKA THROUGH THE EARLY MORNING. CEILINGS WILL LOWER INTO MVFR
CATEGORIES AFTER 1506Z. CEILINGS WILL RISE INTO VFR CATEGORIES
SATURDAY MORNING OVER WESTERN NEBRASKA.
&&
.PREV DISCUSSION... /ISSUED 943 PM CST FRI DEC 14 2012/
UPDATE...
LOWERED TEMPERATURES AND ADJUSTED PRECIPITATION TYPES FOR LOWER
TEMPERATURES. LOADED NEW WINDS AND WIND GUSTS.
PREV DISCUSSION... /ISSUED 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.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...POWER
AREA FORECAST DISCUSSION
NWS BISMARCK ND
242 AM CST SAT DEC 15 2012
.SHORT TERM...TODAY THROUGH SUNDAY...
FORECAST CHALLENGES TODAY CONTINUE WITH AREAS OF DENSE FOG AND AN
ONGOING DENSE FOG ADVISORY...AND PRECIPITATION CHANCES IN THE FAR
SOUTHEAST COUNTIES. THE LATEST WATER VAPOR SHOWS A SPLIT FLOW
REGIME WITH A POTENT UPPER/SFC LOW VIA THE SOUTHERN STREAM ACROSS
NEBRASKA/IOWA MOVING NORTHEAST WITH TIME. IN THE NORTHERN
BRANCH...AN UPPER TROUGH WAS SEEN PUSHING THROUGH WESTERN MONTANA
INTO SOUTHERN CANADA. A SURFACE COLD FRONT WAS MOVING THROUGH
CENTRAL NORTH DAKOTA.
REGIONAL RADAR SHOWS A GRADUAL NORTHWARD SHIFT IN A PRECIPITATION
BAND ACROSS CENTRAL/SOUTHERN SOUTH DAKOTA. THE HRRR CONTINUES TO
HAVE THE BEST HANDLE ON THE AREA AND HAVE FOLLOWED IT CLOSER THAN
THE 00Z NAM/GFS. HPC WWD DESK DRAWS THE MEASURABLE PRECIPITATION
AREA OF FREEZING RAIN RIGHT TO OUR CWA BORDER WITH KABR AND KFGF.
TOO CLOSE TO CALL AT THIS TIME ON HOW FAR WEST FROM THAT POINT IT
WILL END UP PRECIPITATING...HOWEVER ENOUGH EVIDENCE WITH CURRENT
WEATHER TO GIVE THE HRRR THE MAJORITY VOTE. AFTER COLLABORATING
WITH ABR/FGF HAVE INCORPORATED A CHC OF A WINTRY MIX ACROSS
DICKEY/LAMOURE COUNTIES THROUGH THE MORNING AND THEN SHIFTING EAST
IN THE AFTERNOON. ELSEWHERE THE STRATUS AND AREAS OF DENSE FOG
CONTINUE. IT REMAINS UNCLEAR ON HOW MUCH OF THIS WILL LIFT TODAY
DESPITE SOME WEAK/SHALLOW MIXING FOLLOWING A COLD FRONTAL PASSAGE.
WILL PRETTY MUCH MAINTAIN MOSTLY CLOUDY SKIES TODAY. FOR NOW
EXPECTATIONS ARE THAT THE DENSE FOG WILL BE ABLE TO EXPIRE AT 12Z
TODAY...BUT WILL CONTINUE TO MONITOR THE TRENDS AND ADJUST IF NEEDED.
A QUIET WEATHER PERIOD SATURDAY NIGHT...AHEAD OF A SHORTWAVE TROUGH
WHICH WILL IMPINGE UPON THE SOUTHWEST DURING THE DAY SUNDAY.
MODELS INDICATE ENOUGH LIFT TO GENERATE SOME SNOW/LIGHT QPF. HAVE
MENTIONED A CHANCE OF SNOW IN THE GRIDS. DRY ELSEWHERE BUT COLD
WITH HIGHS IN THE TEENS NORTH TO 20S SOUTH.
.LONG TERM...SUNDAY NIGHT THROUGH WEDNESDAY...
DYNAMIC FLOW ACROSS NORTH AMERICA IN THE EXTENDED PERIODS. SUNDAY
NIGHT AT THE BEGINNING OF THE EXTENDED PERIODS HAS WEAK SHORTWAVE IN
NEARLY ZONAL FLOW APPROACHING THE WESTERN COUNTIES WITH BOTH THE
EURO AND GFS ADVERTISING A SMALL AREA OF QPF ACROSS WESTERN AND
CENTRAL NORTH DAKOTA. LARGER SYSTEM WEDNESDAY NIGHT IS FORECAST TO
MOVE THROUGH SOUTHERN SOUTH DAKOTA MISSING WESTERN AND CENTRAL NORTH
DAKOTA. BY THE END OF THE WEEK RIDGING BEGINS TO BUILD OVER THE
WESTERN STATES WITH A DEEP LOW SOUTH OF THE GREAT LAKES FOR MILDER
AND DRIER CONDITIONS.
&&
.AVIATION...LARGE AREA OF VARIABLE IFR AND LOW IFR CEILINGS AND
VISIBILITIES IS TRAPPED OVER CENTRAL NORTH DAKOTA FROM THE SOUTH
DAKOTA BORDER SOUTH OF BISMARCK NORTH TO THE CANADIAN BORDER IN
ROLETTE COUNTY. JUST ENOUGH MIXING TO KEEP THE LAYER UNSTABLE WITH
LARGE VARIATIONS IN AREAL COVERAGE OF CEILING HEIGHTS AND
VISIBILITIES. 12Z TAFS WILL ATTEMPT TO KEEP THE CONDITIONS ON THE
LOW END OF THE SPECTRUM OF CHANGES.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 6 AM CST /5 AM MST/ EARLY THIS MORNING
FOR NDZ003>005-011>013-019>023-025-034>037-042-045-046.
&&
$$
SHORT TERM...KS
LONG TERM/AVIATION...HW
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1141 PM CST FRI DEC 14 2012
.DISCUSSION...LATEST REGIONAL RADAR LOOP SHOWS MEASURABLE
PRECIPITATION IN CENTRAL/SOUTHERN SOUTH DAKOTA FROM CHAMBERLAIN TO
MITCHELL AND INTO BROOKINGS. THE NAM APPEARS TO FAR SOUTH AND THE
HRRR AND GFS ARE BOTH CLOSER TO REALITY. WITH THAT SAID...THE HRRR
DOES SWING A BAND OF PRECIPITATION INTO OUR FAR SOUTHEAST COUNTIES
OF DICKEY AND LAMOURE BY AROUND 10Z. THE GFS GRAZES THIS AREA WITH
A HUNDREDTH OR SO THROUGH 18Z SATURDAY. WITH A COLD FRONT CURRENTLY
SLICING THROUGH CENTRAL AND SOUTHWEST NORTH DAKOTA...IT APPEARS
THAT IT WILL REACH THE SOUTHEAST NEAR 12Z SATURDAY. WITH AN INVERTED
SURFACE TROUGH NOW REACHING INTO OUR SOUTHEAST COUNTIES...AND THE
APPROACH OF THE COLD FRONT ALONG WITH SUFFICIENT LOW LEVEL
MOISTURE...FEEL THERE IS ENOUGH SURFACE CONVERGENCE AND WEAK
LIFT/OMEGA ALOFT FOR SOME VALIDITY IN THE HRRR MODEL. HENCE WILL
ADD A SLIGHT CHC MENTION OF FRZG RAIN/SNOW/SLEET IN THIS AREA
THROUGH THE OVERNIGHT PERIOD. WILL MONITOR HOW THINGS PROGRESS
OVERNIGHT BEFORE ADDING ANYTHING PAST THE 12Z TIMEFRAME. THE DENSE
FOG ADVISORY REMAINS ON TRACK FOR THE OVERNIGHT AND WILL NOT MAKE
ANY CHANGES. REST OF FORECAST LOOKS GOOD.
&&
.AVIATION...FOR THE 06 UTC TAF ISSUANCE...BAND OF LIFR STRATUS AND
FOG CONTINUES ALONG THE LOWER MISSOURI RIVER VALLEY...THEN NORTH TO
MINOT...BOTTINEAU AND RUGBY. WILLISTON MINOT AND DICKINSON ARE
CURRENTLY VFR BUT MINOT IS ON THE EDGE OF THE STRATUS FIELD AND
WILLISTON AND DICKINSON HAVE SEEN PERIODS OF LOW STRATUS AND FOG
OVER THE PAST FEW HOURS WITH ADDITIONAL LOW STRATUS UPSTREAM. WILL
HIT BISMARCK HARDEST WITH IFR CEILINGS/VISIBILITIES THROUGH AROUND
12 UTC...BUT KEEP AT LEAST A MENTION OF FOG/STRATUS AT THE OTHER TAF
SITES. JAMESTOWN HAS SEEN SOME DRIER AIR AND HIGH LEVEL CLOUDS MOVE
IN AND MAY BE OUT OF THE WOODS AS FAR AS LOW CLOUDS AND STRATUS
TONIGHT.
FLOW WILL TURN NORTH TO NORTHWEST LATER TONIGHT AND SATURDAY
INCREASING TO AROUND 10 KNOTS BUT MODELS INDICATE LOW LEVEL MOISTURE
WILL NOT COMPLETELY SCOUR OUT. EVEN THOUGH WE BRING A GOOD PERIOD
OF VFR CEILING SATURDAY...CONFIDENCE IS NOT HIGH AS PATCHY IFR
CLOUDINESS IS ALREADY NOTED UPSTREAM IN SASKATCHEWAN.
TOO MUCH UNCERTAINTY TO MENTION IN TAFS AT THIS TIME BUT BUFKIT IS
INDICATING SOME LOW LEVEL MOISTURE REMAINING SATURDAY NIGHT WHICH
COULD BRING ANOTHER ROUND OF PATCHY FOG/STRATUS.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 6 AM CST /5 AM MST/ SATURDAY FOR
NDZ003>005-011>013-019>023-025-034>037-042-045-046.
&&
$$
DISCUSSION...KS
AVIATION...TWH
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1137 PM CST FRI DEC 14 2012
.DISCUSSION...
/SEE BELOW FOR AVIATION DISCUSSION/
&&
.AVIATION...
FRONT HAS PUSHED SOUTHEAST OF THE REGION WITH DRIER WESTERLY
AIR MOVING IN BEHIND. KBBD AND KJCT CIGS SHOULD RISE TO VFR 6Z TO
7Z. WEST WINDS GUST UP TO 30 KTS MID TO LATE MORNING AT KABI..AS
SURFACE LOW IN KANSAS HEADS NORTHEAST AND BRINGS A STRONG PRESSURE
GRADIENT. WINDS WEAKEN AT KABI MID/LATE AFTERNOON SATURDAY...AND
DECOUPLE AT SUNSET. PRESSURE GRADIENT AND WINDS WILL BE LOWER
FARTHER SOUTH.
&&
.PREV DISCUSSION... /ISSUED 1110 PM CST FRI DEC 14 2012/
UPDATE...
THE PACIFIC FRONT HAS MOVED EAST OF OUR AREA. THE LATEST SATELLITE
AND WSR-88D DATA INDICATE THE LINE OF SHOWERS AND THUNDERSTORMS
HAS ALSO MOVED EAST. LOW CLOUDS STILL COVER MOST OF WEST CENTRAL
TEXAS...AND HIGH CLOUDS STILL STREAM OVER MUCH OF TEXAS FROM THE
SOUTHWEST. I REMOVED POPS AND WEATHER FOR THE REMAINDER OF
TONIGHT. PLUS...I ADJUSTED WIND...TEMPERATURE...AND DEWPOINT GRIDS
FOR THE REMAINDER OF TONIGHT TO BRING THEM IN LINE WITH CURRENT
CONDITIONS AND RUC SHORT-TERM FORECASTS. THE LATEST ZONE FORECAST
PRODUCT REFLECTS THESE ADJUSTMENTS.
HUBER
PREV DISCUSSION... /ISSUED 542 PM CST FRI DEC 14 2012/
DISCUSSION...
/SEE BELOW FOR AVIATION DISCUSSION/
AVIATION...
STRONG WINDS AT ABILENE POSSIBLE EARLY THIS EVENING. LINE OF
SHOWERS 60 MILES WEST OF ABILENE AT 2330Z WAS MOVING EAST AT 40
KTS AND MAY AFFECT KABI 1Z TO 2Z. WINDS ON THE DYESS RADAR JUST
ABOVE THE SURFACE WERE 40 KTS...AND SHOWERS COULD BRING THOSE
WINDS TO THE SURFACE...IF THEY PERSIST. MVFR CIGS OTHERWISE
SCATTER OUT TO VFR FROM WEST TO EAST THROUGH 6Z...AS DRIER AIR
WORKS IN FROM THE WEST. WIND GUSTS TO 30 KTS POSSIBLE AT KABI AND
KSJT MID MORNING SATURDAY AS SURFACE TROUGH MOVES THROUGH.
04
PREV DISCUSSION... /ISSUED 354 PM CST FRI DEC 14 2012/
SHORT TERM...
STRONG UPPER LEVEL TROF OVER THE FOUR CORNERS THIS AFTERNOON...
MOVING NORTHEAST. AT THE SURFACE...SOUTHERLY FLOW CONTINUES ACROSS
WEST CENTRAL TEXAS AHEAD OF PACIFIC COLD FRONT LOCATED ALONG THE
NEW MEXICO/TEXAS BORDER. WINDS HAVE BEEN GUSTING TO 35 TO 40 MPH
AT TIMES. LINE OF CONVECTION HAS FIRED ALONG THE FRONT AND IS
BEING AIDED BY STRONG 0-6KM SHEAR. THIS LINE OF STORMS IS MOVING
RAPIDLY TO THE EAST.
UPPER TROUGH OVER THE FOUR CORNERS WILL LIFT NORTHEAST INTO THE
CENTRAL PLAINS BY TONIGHT. THE MOVEMENT OF THE UPPER LEVEL SYSTEM
WILL HELP SEND THE PACIFIC COLD FRONT ACROSS WEST CENTRAL TEXAS
TONIGHT. THERE WILL BE A CHANCE OF SHOWERS AND A FEW THUNDERSTORMS
ACROSS THE EASTERN 2/3 OF THE AREA THIS EVENING. THE CURRENT LINE
OF STORMS APPROACHING A LUBBOCK TO MIDLAND LINE...HAS A CHANCE
OF MAKING THE BIG COUNTRY THIS EVENING. HOWEVER...ABUNDANT LOW
LEVEL CLOUDS OVER OUR AREA WILL RESULT IN WEAK INSTABILITY...WHICH
MAY WEAKEN THE SOUTHERN END OF THE LINE. ALSO...STRONGEST UPPER
LEVEL FORCING WILL REMAIN TO OUR NORTH. RAINFALL AMOUNTS WILL
REMAIN LIGHT...GENERALLY LESS THAN 1/10 OF AN INCH. COOLER
TEMPERATURES TONIGHT WITH LOWS IN THE 40S.
FOR SATURDAY...LOW LEVEL WESTERLY FLOW BEHIND DEPARTING UPPER
LEVEL SYSTEM WILL BRING GUSTY WINDS DURING THE AFTERNOON. WIND
SPEEDS ACROSS THE NORTHERN HALF OF THE AREA WILL BE 15 TO 25 MPH
WITH A FEW GUSTS TO 30 MPH. TEMPERATURES WILL BE MILD WITH HIGHS
UPPER 60S TO LOWER 70S.
21
LONG TERM...
THE MID LEVEL TROF AXIS WILL BE APPROACHING WEST TX BY 00Z SUNDAY
WITH STRONG SOUTH TO SOUTHWEST FLOW THROUGH MOST OF THE
TROPOSPHERE. WINDS LOOK TO BE FAIRLY UNIDIRECTIONAL THROUGH
APPROXIMATELY H7 AND DOWNWARD MOMENTUM TRANSPORT WILL INCREASE
WITH THE SUBSIDENCE ASSOCIATED WITH THE LEFT ENTRANCE REGION TO
THE H25 JET. THIS WILL SUPPORT WINDY CONDITIONS AGAIN WITH TEMPS
CONTINUING AT NEARLY 10 DEGREES ABOVE CLIMO. WIND SPEEDS ARE
EXPECTED TO INCREASE TO NEAR 20 MPH THROUGH MID AFTERNOON BEFORE
DECREASING AROUND SUNSET. EXPECT HIGHS ON SUNDAY IN THE MID 60S TO
NEAR 70 DEGREES.
INCREASING LARGE SCALE SUBSIDENCE WILL ERODE THE HIGH CLOUDS BY
MONDAY. WINDS ARE EXPECTED TO VEER A BIT MORE TO THE NORTHWEST BUT
SHOULD GENERALLY REMAIN LESS THAN 15 MPH. TEMPS ARE EXPECTED TO
REMAIN IN THE MID/UPPER 60S WITH NIL RAIN CHANCES.
WE WILL SEE A WARM-UP DURING THE MIDWEEK PERIOD AS LEE TROFFING
RESUMES AND SOUTHWEST WINDS RETURN. THE H85 THERMAL RIDGE IS
PROGGED TO INCREASE TO 16C BY TUESDAY WHICH WILL SUPPORT MAX
TEMPS IN THE LOW/MID 70S. A POTENT...POSITIVELY TILTED TROUGH WILL
BE MOVING ACROSS THE GREAT BASIN BY TUESDAY...WITH THE SURFACE LEE
CYCLONE EVENTUALLY BREAKING AWAY FROM THE HIGHER TERRAIN AND
MOVING INTO THE PLAINS. THIS TENDS TO INCREASE THE STRENGTH OF THE
THERMAL RIDGE AND WARMING TEMPS FURTHER. THE GFS IS A BIT WEAKER
WITH THIS THERMAL RIDGE THAN THE ECMWF WHICH MAY BE...IN
PART...DUE TO THE POORER RESOLUTION. THE H5 TROUGH AXES ARE IN
SIMILAR LOCATIONS BUT THE ECMWF KEEPS THE LEE CYCLONE A BIT
FARTHER WEST THROUGH WEDNESDAY AFTERNOON. I LIKE THIS SOLUTION AS
IT WILL LIKELY WAIT FOR THE PRIMARY SHORTWAVE TO ARRIVE BEFORE
MOVING EAST. THIS WOULD RESULT IN WARMER TEMPS ON WEDNESDAY THAN
DEPICTED BY THE GFS. I KEPT THE TREND FROM THE PREVIOUS
FORECAST...WITH HIGHS IN THE MID/UPPER 70S.
THE NEXT SIGNIFICANT COLD FRONT IS CURRENTLY EXPECTED TO ARRIVE
WEDNESDAY NIGHT...PROVIDING COOLER AND DRIER WEATHER TO WEST CENTRAL
TX THROUGH THE REMAINDER OF THE WORK WEEK. I DO NOT ANTICIPATE ANY
PRECIP WITH THIS SYSTEM AS WE SHOULD SEE ONLY A BRIEF /AND MEAGER/
RETURN OF GULF MOISTURE. AS USUAL...EXPECT THE BEST RAIN CHANCES TO
THE EAST OF THE CWA.
JOHNSON
FIRE WEATHER...
CRITICAL FIRE WEATHER CONDITIONS ARE POSSIBLE ACROSS THE BIG
COUNTRY AND CONCHO VALLEY SATURDAY AFTERNOON DUE TO 20 FOOT WEST
WINDS OF 20 MPH WITH HIGHER GUSTS AND RELATIVE HUMIDITIES OF 15 TO
20 PERCENT. A FIRE WEATHER WATCH IS IN EFFECT FOR THESE AREAS.
ELEVATED TO NEAR CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED
ACROSS MUCH OF THE AREA AGAIN ON SUNDAY.
21
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 42 68 43 67 37 / 10 0 0 0 0
SAN ANGELO 43 71 40 68 36 / 10 0 0 0 0
JUNCTION 44 73 41 71 36 / 10 5 0 0 0
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH SATURDAY AFTERNOON FOR THE FOLLOWING ZONES:
CALLAHAN...COKE...CONCHO...FISHER...HASKELL...IRION...JONES...
NOLAN...RUNNELS...SHACKELFORD...STERLING...TAYLOR...
THROCKMORTON...TOM GREEN.
&&
$$
99/99/04
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1110 PM CST FRI DEC 14 2012
.UPDATE...
THE PACIFIC FRONT HAS MOVED EAST OF OUR AREA. THE LATEST SATELLITE
AND WSR-88D DATA INDICATE THE LINE OF SHOWERS AND THUNDERSTORMS
HAS ALSO MOVED EAST. LOW CLOUDS STILL COVER MOST OF WEST CENTRAL
TEXAS...AND HIGH CLOUDS STILL STREAM OVER MUCH OF TEXAS FROM THE
SOUTHWEST. I REMOVED POPS AND WEATHER FOR THE REMAINDER OF
TONIGHT. PLUS...I ADJUSTED WIND...TEMPERATURE...AND DEWPOINT GRIDS
FOR THE REMAINDER OF TONIGHT TO BRING THEM IN LINE WITH CURRENT
CONDITIONS AND RUC SHORT-TERM FORECASTS. THE LATEST ZONE FORECAST
PRODUCT REFLECTS THESE ADJUSTMENTS.
HUBER
&&
.PREV DISCUSSION... /ISSUED 542 PM CST FRI DEC 14 2012/
DISCUSSION...
/SEE BELOW FOR AVIATION DISCUSSION/
AVIATION...
STRONG WINDS AT ABILENE POSSIBLE EARLY THIS EVENING. LINE OF
SHOWERS 60 MILES WEST OF ABILENE AT 2330Z WAS MOVING EAST AT 40
KTS AND MAY AFFECT KABI 1Z TO 2Z. WINDS ON THE DYESS RADAR JUST
ABOVE THE SURFACE WERE 40 KTS...AND SHOWERS COULD BRING THOSE
WINDS TO THE SURFACE...IF THEY PERSIST. MVFR CIGS OTHERWISE
SCATTER OUT TO VFR FROM WEST TO EAST THROUGH 6Z...AS DRIER AIR
WORKS IN FROM THE WEST. WIND GUSTS TO 30 KTS POSSIBLE AT KABI AND
KSJT MID MORNING SATURDAY AS SURFACE TROUGH MOVES THROUGH.
04
PREV DISCUSSION... /ISSUED 354 PM CST FRI DEC 14 2012/
SHORT TERM...
STRONG UPPER LEVEL TROF OVER THE FOUR CORNERS THIS AFTERNOON...
MOVING NORTHEAST. AT THE SURFACE...SOUTHERLY FLOW CONTINUES ACROSS
WEST CENTRAL TEXAS AHEAD OF PACIFIC COLD FRONT LOCATED ALONG THE
NEW MEXICO/TEXAS BORDER. WINDS HAVE BEEN GUSTING TO 35 TO 40 MPH
AT TIMES. LINE OF CONVECTION HAS FIRED ALONG THE FRONT AND IS
BEING AIDED BY STRONG 0-6KM SHEAR. THIS LINE OF STORMS IS MOVING
RAPIDLY TO THE EAST.
UPPER TROUGH OVER THE FOUR CORNERS WILL LIFT NORTHEAST INTO THE
CENTRAL PLAINS BY TONIGHT. THE MOVEMENT OF THE UPPER LEVEL SYSTEM
WILL HELP SEND THE PACIFIC COLD FRONT ACROSS WEST CENTRAL TEXAS
TONIGHT. THERE WILL BE A CHANCE OF SHOWERS AND A FEW THUNDERSTORMS
ACROSS THE EASTERN 2/3 OF THE AREA THIS EVENING. THE CURRENT LINE
OF STORMS APPROACHING A LUBBOCK TO MIDLAND LINE...HAS A CHANCE
OF MAKING THE BIG COUNTRY THIS EVENING. HOWEVER...ABUNDANT LOW
LEVEL CLOUDS OVER OUR AREA WILL RESULT IN WEAK INSTABILITY...WHICH
MAY WEAKEN THE SOUTHERN END OF THE LINE. ALSO...STRONGEST UPPER
LEVEL FORCING WILL REMAIN TO OUR NORTH. RAINFALL AMOUNTS WILL
REMAIN LIGHT...GENERALLY LESS THAN 1/10 OF AN INCH. COOLER
TEMPERATURES TONIGHT WITH LOWS IN THE 40S.
FOR SATURDAY...LOW LEVEL WESTERLY FLOW BEHIND DEPARTING UPPER
LEVEL SYSTEM WILL BRING GUSTY WINDS DURING THE AFTERNOON. WIND
SPEEDS ACROSS THE NORTHERN HALF OF THE AREA WILL BE 15 TO 25 MPH
WITH A FEW GUSTS TO 30 MPH. TEMPERATURES WILL BE MILD WITH HIGHS
UPPER 60S TO LOWER 70S.
21
LONG TERM...
THE MID LEVEL TROF AXIS WILL BE APPROACHING WEST TX BY 00Z SUNDAY
WITH STRONG SOUTH TO SOUTHWEST FLOW THROUGH MOST OF THE
TROPOSPHERE. WINDS LOOK TO BE FAIRLY UNIDIRECTIONAL THROUGH
APPROXIMATELY H7 AND DOWNWARD MOMENTUM TRANSPORT WILL INCREASE
WITH THE SUBSIDENCE ASSOCIATED WITH THE LEFT ENTRANCE REGION TO
THE H25 JET. THIS WILL SUPPORT WINDY CONDITIONS AGAIN WITH TEMPS
CONTINUING AT NEARLY 10 DEGREES ABOVE CLIMO. WIND SPEEDS ARE
EXPECTED TO INCREASE TO NEAR 20 MPH THROUGH MID AFTERNOON BEFORE
DECREASING AROUND SUNSET. EXPECT HIGHS ON SUNDAY IN THE MID 60S TO
NEAR 70 DEGREES.
INCREASING LARGE SCALE SUBSIDENCE WILL ERODE THE HIGH CLOUDS BY
MONDAY. WINDS ARE EXPECTED TO VEER A BIT MORE TO THE NORTHWEST BUT
SHOULD GENERALLY REMAIN LESS THAN 15 MPH. TEMPS ARE EXPECTED TO
REMAIN IN THE MID/UPPER 60S WITH NIL RAIN CHANCES.
WE WILL SEE A WARM-UP DURING THE MIDWEEK PERIOD AS LEE TROFFING
RESUMES AND SOUTHWEST WINDS RETURN. THE H85 THERMAL RIDGE IS
PROGGED TO INCREASE TO 16C BY TUESDAY WHICH WILL SUPPORT MAX
TEMPS IN THE LOW/MID 70S. A POTENT...POSITIVELY TILTED TROUGH WILL
BE MOVING ACROSS THE GREAT BASIN BY TUESDAY...WITH THE SURFACE LEE
CYCLONE EVENTUALLY BREAKING AWAY FROM THE HIGHER TERRAIN AND
MOVING INTO THE PLAINS. THIS TENDS TO INCREASE THE STRENGTH OF THE
THERMAL RIDGE AND WARMING TEMPS FURTHER. THE GFS IS A BIT WEAKER
WITH THIS THERMAL RIDGE THAN THE ECMWF WHICH MAY BE...IN
PART...DUE TO THE POORER RESOLUTION. THE H5 TROUGH AXES ARE IN
SIMILAR LOCATIONS BUT THE ECMWF KEEPS THE LEE CYCLONE A BIT
FARTHER WEST THROUGH WEDNESDAY AFTERNOON. I LIKE THIS SOLUTION AS
IT WILL LIKELY WAIT FOR THE PRIMARY SHORTWAVE TO ARRIVE BEFORE
MOVING EAST. THIS WOULD RESULT IN WARMER TEMPS ON WEDNESDAY THAN
DEPICTED BY THE GFS. I KEPT THE TREND FROM THE PREVIOUS
FORECAST...WITH HIGHS IN THE MID/UPPER 70S.
THE NEXT SIGNIFICANT COLD FRONT IS CURRENTLY EXPECTED TO ARRIVE
WEDNESDAY NIGHT...PROVIDING COOLER AND DRIER WEATHER TO WEST CENTRAL
TX THROUGH THE REMAINDER OF THE WORK WEEK. I DO NOT ANTICIPATE ANY
PRECIP WITH THIS SYSTEM AS WE SHOULD SEE ONLY A BRIEF /AND MEAGER/
RETURN OF GULF MOISTURE. AS USUAL...EXPECT THE BEST RAIN CHANCES TO
THE EAST OF THE CWA.
JOHNSON
FIRE WEATHER...
CRITICAL FIRE WEATHER CONDITIONS ARE POSSIBLE ACROSS THE BIG
COUNTRY AND CONCHO VALLEY SATURDAY AFTERNOON DUE TO 20 FOOT WEST
WINDS OF 20 MPH WITH HIGHER GUSTS AND RELATIVE HUMIDITIES OF 15 TO
20 PERCENT. A FIRE WEATHER WATCH IS IN EFFECT FOR THESE AREAS.
ELEVATED TO NEAR CRITICAL FIRE WEATHER CONDITIONS ARE EXPECTED
ACROSS MUCH OF THE AREA AGAIN ON SUNDAY.
21
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 42 68 43 67 37 / 10 0 0 0 0
SAN ANGELO 43 71 40 68 36 / 10 0 0 0 0
JUNCTION 44 73 41 71 36 / 10 5 0 0 0
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH SATURDAY AFTERNOON FOR THE FOLLOWING ZONES:
CALLAHAN...COKE...CONCHO...FISHER...HASKELL...IRION...JONES...
NOLAN...RUNNELS...SHACKELFORD...STERLING...TAYLOR...
THROCKMORTON...TOM GREEN.
&&
$$
HUBER
AREA FORECAST DISCUSSION
NWS JACKSON KY
953 AM EST SAT DEC 15 2012
.UPDATE...
ISSUED AT 953 AM EST SAT DEC 15 2012
ISENTROPIC LIFT AS A RESULT OF STRENGTHENING 925 TO 850 FLOW IS
RESPONSIBLE FOR SCATTERED SHOWERS ENTERING THE AREA THIS MORNING.
SFC OBS INDICATE THAT MEASURABLE RAIN IS PROBABLY NOT BE REACHING THE
GROUND IN MANY LOCATIONS...BUT EXPECT AT LEAST SOME LIGHT RAINFALL IS
REACHING THE GROUND UNDER 40 DBZ PLUS ECHOS. WHILE STRONGEST ECHOS
SUGGEST ISOLD TO AT TIMES SCATTERED ACTIVITY...FELT SCATTERED
COVERAGE WOULD BETTER SUFFICE AS AN OVERALL EFFECTIVE POP. TEMPS AND
DEW POINTS ARE PRETTY MUCH ON TARGET...SO ONLY SOME MINOR TWEAKS TO
OTHER GRIDS TO ACCOUNT FOR HOURLY TRENDS. DO SEE SOME BREAKS IN CLOUD
COVER...SO DECREASED SKY COVER JUST SLIGHTLY.
UPDATE ISSUED AT 625 AM EST SAT DEC 15 2012
LATEST RUC AND 06Z NAM SHOW MOISTURE VERY LIMITED TODAY AS THE
BOUNDARY SPREADS INTO THE AREA. GIVEN THIS TREND...HAVE OPTED TO
DECREASE POPS THIS AFTERNOON AND EVENING. LOOKS LIKE WE SHOULD SEE
ISOLATED SHOWERS AT BEST. OTHERWISE...REST OF FORECAST IS ON TRACK.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 255 AM EST SAT DEC 15 2012
A STRONG MID LEVEL WAVE WILL PUSH NORTHEAST INTO THE WESTERN GREAT
LAKES TODAY. AT THE SURFACE...THIS WILL SEND A SURFACE LOW TOWARDS
CHICAGO WITH A TRAILING WARM FRONT PUSHING ITS WAY EASTWARD ACROSS
KENTUCKY. THE WARM CONVEYOR BELT WILL CONTINUE TO BRING WIDESPREAD
CLOUD COVER TO THE AREA TODAY. THIS CLOUD COVER WILL KEEP OUR HIGHS
IN CHECK...BUT THEY WILL STILL BE MILD WITH READINGS INTO THE LOWER
60S. AS THE FRONT SPREADS EASTWARD THIS AFTERNOON...SCATTERED
SHOWERS WILL PUSH INTO THE I-75 CORRIDOR AND ACROSS EASTERN KENTUCKY
DURING THE EVENING HOURS. STILL SOME QUESTION AS TO HOW MUCH COVERAGE
WILL BE SEEN WITH THE SHOWER ACTIVITY...BUT ECMWF HAS REALLY BACKED
DOWN TONIGHT...WHILE THE NAM REMAINS A BIT MORE AGGRESSIVE. OPTING TO
GO WITH LOW END POPS FOR NOW...BUT POPS COULD CERTAINLY GO HIGHER IF
COVERAGE ENDS UP BETTER AS THE NAM WOULD SUPPORT.
THIS WARM FRONT WILL STALL ACROSS SOUTHEAST KENTUCKY LATE TONIGHT. A
WEAK WAVE WILL PUSH NORTHEAST ACROSS THE TENNESSEE VALLEY LATE
TONIGHT INTO SUNDAY MORNING AND THIS MAY BRING A BETTER SHOT OF
PRECIPITATION INTO SOUTHEAST KENTUCKY. AGAIN...SOME UNCERTAINTY WITH
REGARD TO HOW FAR NORTH THE PRECIPITATION MAY REACH. GOING TO KEEP
THE HIGHEST POPS IN THE SOUTHEAST AND SLOWLY TRAIL THEM OFF TO THE
NORTH. THE BLUEGRASS COULD STAY DRY THROUGH TONIGHT AND TOMORROW IF
YOU BELIEVE THE ECMWF. LOWS TONIGHT WILL REMAIN IN THE 40S AND 50S
WITH GOOD CLOUD COVER ALONG WITH BEING LOCATED IN THE WARM SECTOR.
HIGHS SUNDAY WILL AGAIN WARM INTO THE 60S...BUT THE DEGREE OF
PRECIPITATION COULD TEMPORARILY KEEP THEM LOWER.
HOWEVER...PRECIPITATION SHOULD MOVE OUT BY MID AFTERNOON. NOT SURE IF
WE CAN SQUEEZE OUT ANY SUNSHINE...BUT IT MAY BE POSSIBLE.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 410 AM EST SAT DEC 15 2012
THE MODELS ARE ONLY IN FAIR AGREEMENT ALOFT THROUGH THE FIRST PART OF
THE EXTENDED AS THEY START WITH A BROAD TROUGH OVER THE CENTRAL
PLAINS AND VARIOUS SHORT WAVES CROSSING THE BREADTH OF THE NATION.
THIS TROUGH GRADUALLY EVOLVES INTO A SHARPER VERSION OF ITSELF AND
SWINGS THROUGH THE OHIO VALLEY ON MONDAY. AS IT DOES SO...THE LATEST
ECMWF KEEPS ITS CORE OF ENERGY FURTHER NORTH THAN THE GFS WHILE ALSO
PASSING THROUGH A BIT SLOWER. IRONICALLY...AFTER THIS...OUT OF SYNC
MODEL-WISE...SYSTEM LIFTS OUT OF THE AREA THE MEDIUM RANGE PROGS COME
INTO BETTER AGREEMENT ON THE RIDGING THAT FOLLOWS FOR MID WEEK AND
FOR THE MID SECTION OF THE COUNTRY. THIS RIDGE WILL MOVE THROUGH
FAIRLY QUICK ON WEDNESDAY AND WEDNESDAY NIGHT...THOUGH...AND
ATTENTION WILL...IN SHORT ORDER...TURN TOWARD A BREWING TROUGH
THAT WILL BE PLOWING THROUGH THE SOUTHERN PLAINS. HERE...THE ECMWF IS
THE STRONGEST SOLUTION...BUT THE TIMING AND AMPLITUDE ARE SIMILAR TO
THE GFS AND GEM...GIVING THE WHOLE IDEA ENHANCED CREDENCE. THIS
DEEPENING LOW CLOSES OFF AND ROLLS ACROSS THE MISSISSIPPI RIVER ON
THURSDAY AND INTO THE OHIO VALLEY. WITH THIS...THE MODELS ARE
ACTUALLY IN PRETTY GOOD AGREEMENT FOR A FORECAST 144 HOURS OUT. THE
DEEP CLOSED LOW THEN WOULD PLOD ACROSS THE OHIO VALLEY ON FRIDAY WITH
THE ECMWF LESS PROGRESSIVE THAN THE GFS. HAVE FAVORED A BLEND OF
MODEL SOLUTIONS THROUGH THE FIRST PART OF THE EXTENDED...IN LINE
WITH THE CR MODEL LOAD...BUT PREFER THE MORE AMPLIFIED VERSION OF THE
ECMWF FOR THE LATTER PERIODS OF THE FORECAST GIVEN THE APPARENT
MAGNITUDE OF THE UPCOMING PATTERN CHANGE.
SENSIBLE WEATHER WILL FEATURE A CHANCE OF SHOWERS CONTINUING THROUGH
THE SOUTHERN PORTION OF THE CWA ON SUNDAY NIGHT...STRETCHING
NORTHWEST WITH TIME AS A FINAL SFC WAVE PASSES THROUGH THE AREA ON
MONDAY BEFORE CLEARING AND TAKING THE BULK OF THE PCPN CHANCES WITH
IT ON MONDAY NIGHT. A FEW SHOWERS MAY LINGER IN THE FAR EAST EARLY ON
TUESDAY...BUT...FOR THE MOST PART...HIGH PRESSURE WILL BUILD INTO
THE AREA AND PROVIDE WHAT APPEARS TO BE ONE LAST WARM SHOT FOR THE
MONTH AROUND MIDWEEK...AHEAD OF A POTENT SYSTEM DUE IN HERE TO END
THE WORK WEEK. THIS FINAL SYSTEM...OF THE EXTENDED AND BEYOND...WILL
BE DEEPENING AS IT MOVES THROUGH AND WILL BRING A GOOD SLUG OF
MOISTURE AHEAD OF ITS COLD FRONT FOLLOWED BY PLENTY OF COLD AIR IN
ITS WAKE. THE SLOW AND STRENGTHENING NATURE OF THE LOW WILL PROBABLY
KEEP ITS WRAP AROUND PCPN IN THE AREA THROUGH FRIDAY...WITH MUCH OF
THIS FALLING AS LIGHT SNOW SHOWERS AND PRESENTING A POTENTIAL FOR AN
EXTENDED PERIOD WINTRY WEATHER INTO THE WEEKEND...DEFINITELY MORE THAN
WE HAVE SEEN THUS FAR THIS SEASON.
THE CR GRID BLEND CAME IN REASONABLE...BUT DID NUDGE IT MORE TOWARD
THE ECMWF IN THE LATTER PERIODS...PARTICULARLY WITH RESPECT TO POPS.
ALSO...MADE SOME MINOR TERRAIN BASED ADJUSTMENTS TO LOW TEMPERATURES
FOR TUESDAY AND WEDNESDAY NIGHT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 625 AM EST SAT DEC 15 2012
VFR CONDITIONS WILL CONTINUE OVER THE NEXT 24 HOURS WITH SOME LOWER
SUB-VFR CIGS ARRIVING AROUND OR SHORTLY AFTER 12Z SUNDAY MORNING.
THIS IS BEYOND THE TAF FORECAST PERIOD HOWEVER. IN THE
MEANTIME...HIGH CLOUDS WILL SPREAD ACROSS THE AREA TODAY WITH 4-5KFT
CIGS ARRIVING WITH THE WARM FRONT THIS EVENING. IN ADDITION A STRAY
SHOWER WILL BE POSSIBLE AS THE FRONT MOVES ACROSS THE AREA LATER THIS
EVENING. GENERALLY LIGHT SOUTHERLY WINDS ARE ANTICIPATED THROUGH THE
PERIOD. THE WARM FRONTAL PASSAGE TONIGHT COULD LEAD TO THE
DEVELOPMENT OF SOME LLWS LATE THIS EVENING AND CONTINUING OVERNIGHT.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
UPDATE...RAY
SHORT TERM...KAS
LONG TERM....GREIF
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS JACKSON KY
625 AM EST SAT DEC 15 2012
.UPDATE...
ISSUED AT 625 AM EST SAT DEC 15 2012
LATEST RUC AND 06Z NAM SHOW MOISTURE VERY LIMITED TODAY AS THE
BOUNDARY SPREADS INTO THE AREA. GIVEN THIS TREND...HAVE OPTED TO
DECREASE POPS THIS AFTERNOON AND EVENING. LOOKS LIKE WE SHOULD SEE
ISOLATED SHOWERS AT BEST. OTHERWISE...REST OF FORECAST IS ON TRACK.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 255 AM EST SAT DEC 15 2012
A STRONG MID LEVEL WAVE WILL PUSH NORTHEAST INTO THE WESTERN GREAT
LAKES TODAY. AT THE SURFACE...THIS WILL SEND A SURFACE LOW TOWARDS
CHICAGO WITH A TRAILING WARM FRONT PUSHING ITS WAY EASTWARD ACROSS
KENTUCKY. THE WARM CONVEYOR BELT WILL CONTINUE TO BRING WIDESPREAD
CLOUD COVER TO THE AREA TODAY. THIS CLOUD COVER WILL KEEP OUR HIGHS
IN CHECK...BUT THEY WILL STILL BE MILD WITH READINGS INTO THE LOWER
60S. AS THE FRONT SPREADS EASTWARD THIS AFTERNOON...SCATTERED
SHOWERS WILL PUSH INTO THE I-75 CORRIDOR AND ACROSS EASTERN KENTUCKY
DURING THE EVENING HOURS. STILL SOME QUESTION AS TO HOW MUCH COVERAGE
WILL BE SEEN WITH THE SHOWER ACTIVITY...BUT ECMWF HAS REALLY BACKED
DOWN TONIGHT...WHILE THE NAM REMAINS A BIT MORE AGGRESSIVE. OPTING TO
GO WITH LOW END POPS FOR NOW...BUT POPS COULD CERTAINLY GO HIGHER IF
COVERAGE ENDS UP BETTER AS THE NAM WOULD SUPPORT.
THIS WARM FRONT WILL STALL ACROSS SOUTHEAST KENTUCKY LATE TONIGHT. A
WEAK WAVE WILL PUSH NORTHEAST ACROSS THE TENNESSEE VALLEY LATE
TONIGHT INTO SUNDAY MORNING AND THIS MAY BRING A BETTER SHOT OF
PRECIPITATION INTO SOUTHEAST KENTUCKY. AGAIN...SOME UNCERTAINTY WITH
REGARD TO HOW FAR NORTH THE PRECIPITATION MAY REACH. GOING TO KEEP
THE HIGHEST POPS IN THE SOUTHEAST AND SLOWLY TRAIL THEM OFF TO THE
NORTH. THE BLUEGRASS COULD STAY DRY THROUGH TONIGHT AND TOMORROW IF
YOU BELIEVE THE ECMWF. LOWS TONIGHT WILL REMAIN IN THE 40S AND 50S
WITH GOOD CLOUD COVER ALONG WITH BEING LOCATED IN THE WARM SECTOR.
HIGHS SUNDAY WILL AGAIN WARM INTO THE 60S...BUT THE DEGREE OF
PRECIPITATION COULD TEMPORARILY KEEP THEM LOWER.
HOWEVER...PRECIPITATION SHOULD MOVE OUT BY MID AFTERNOON. NOT SURE IF
WE CAN SQUEEZE OUT ANY SUNSHINE...BUT IT MAY BE POSSIBLE.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 410 AM EST SAT DEC 15 2012
THE MODELS ARE ONLY IN FAIR AGREEMENT ALOFT THROUGH THE FIRST PART OF
THE EXTENDED AS THEY START WITH A BROAD TROUGH OVER THE CENTRAL
PLAINS AND VARIOUS SHORT WAVES CROSSING THE BREADTH OF THE NATION.
THIS TROUGH GRADUALLY EVOLVES INTO A SHARPER VERSION OF ITSELF AND
SWINGS THROUGH THE OHIO VALLEY ON MONDAY. AS IT DOES SO...THE LATEST
ECMWF KEEPS ITS CORE OF ENERGY FURTHER NORTH THAN THE GFS WHILE ALSO
PASSING THROUGH A BIT SLOWER. IRONICALLY...AFTER THIS...OUT OF SYNC
MODEL-WISE...SYSTEM LIFTS OUT OF THE AREA THE MEDIUM RANGE PROGS COME
INTO BETTER AGREEMENT ON THE RIDGING THAT FOLLOWS FOR MID WEEK AND
FOR THE MID SECTION OF THE COUNTRY. THIS RIDGE WILL MOVE THROUGH
FAIRLY QUICK ON WEDNESDAY AND WEDNESDAY NIGHT...THOUGH...AND
ATTENTION WILL...IN SHORT ORDER...TURN TOWARD A BREWING TROUGH
THAT WILL BE PLOWING THROUGH THE SOUTHERN PLAINS. HERE...THE ECMWF IS
THE STRONGEST SOLUTION...BUT THE TIMING AND AMPLITUDE ARE SIMILAR TO
THE GFS AND GEM...GIVING THE WHOLE IDEA ENHANCED CREDENCE. THIS
DEEPENING LOW CLOSES OFF AND ROLLS ACROSS THE MISSISSIPPI RIVER ON
THURSDAY AND INTO THE OHIO VALLEY. WITH THIS...THE MODELS ARE
ACTUALLY IN PRETTY GOOD AGREEMENT FOR A FORECAST 144 HOURS OUT. THE
DEEP CLOSED LOW THEN WOULD PLOD ACROSS THE OHIO VALLEY ON FRIDAY WITH
THE ECMWF LESS PROGRESSIVE THAN THE GFS. HAVE FAVORED A BLEND OF
MODEL SOLUTIONS THROUGH THE FIRST PART OF THE EXTENDED...IN LINE
WITH THE CR MODEL LOAD...BUT PREFER THE MORE AMPLIFIED VERSION OF THE
ECMWF FOR THE LATTER PERIODS OF THE FORECAST GIVEN THE APPARENT
MAGNITUDE OF THE UPCOMING PATTERN CHANGE.
SENSIBLE WEATHER WILL FEATURE A CHANCE OF SHOWERS CONTINUING THROUGH
THE SOUTHERN PORTION OF THE CWA ON SUNDAY NIGHT...STRETCHING
NORTHWEST WITH TIME AS A FINAL SFC WAVE PASSES THROUGH THE AREA ON
MONDAY BEFORE CLEARING AND TAKING THE BULK OF THE PCPN CHANCES WITH
IT ON MONDAY NIGHT. A FEW SHOWERS MAY LINGER IN THE FAR EAST EARLY ON
TUESDAY...BUT...FOR THE MOST PART...HIGH PRESSURE WILL BUILD INTO
THE AREA AND PROVIDE WHAT APPEARS TO BE ONE LAST WARM SHOT FOR THE
MONTH AROUND MIDWEEK...AHEAD OF A POTENT SYSTEM DUE IN HERE TO END
THE WORK WEEK. THIS FINAL SYSTEM...OF THE EXTENDED AND BEYOND...WILL
BE DEEPENING AS IT MOVES THROUGH AND WILL BRING A GOOD SLUG OF
MOISTURE AHEAD OF ITS COLD FRONT FOLLOWED BY PLENTY OF COLD AIR IN
ITS WAKE. THE SLOW AND STRENGTHENING NATURE OF THE LOW WILL PROBABLY
KEEP ITS WRAP AROUND PCPN IN THE AREA THROUGH FRIDAY...WITH MUCH OF
THIS FALLING AS LIGHT SNOW SHOWERS AND PRESENTING A POTENTIAL FOR AN
EXTENDED PERIOD WINTRY WEATHER INTO THE WEEKEND...DEFINITELY MORE THAN
WE HAVE SEEN THUS FAR THIS SEASON.
THE CR GRID BLEND CAME IN REASONABLE...BUT DID NUDGE IT MORE TOWARD
THE ECMWF IN THE LATTER PERIODS...PARTICULARLY WITH RESPECT TO POPS.
ALSO...MADE SOME MINOR TERRAIN BASED ADJUSTMENTS TO LOW TEMPERATURES
FOR TUESDAY AND WEDNESDAY NIGHT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 625 AM EST SAT DEC 15 2012
VFR CONDITIONS WILL CONTINUE OVER THE NEXT 24 HOURS WITH SOME LOWER
SUB-VFR CIGS ARRIVING AROUND OR SHORTLY AFTER 12Z SUNDAY MORNING.
THIS IS BEYOND THE TAF FORECAST PERIOD HOWEVER. IN THE
MEANTIME...HIGH CLOUDS WILL SPREAD ACROSS THE AREA TODAY WITH 4-5KFT
CIGS ARRIVING WITH THE WARM FRONT THIS EVENING. IN ADDITION A STRAY
SHOWER WILL BE POSSIBLE AS THE FRONT MOVES ACROSS THE AREA LATER THIS
EVENING. GENERALLY LIGHT SOUTHERLY WINDS ARE ANTICIPATED THROUGH THE
PERIOD. THE WARM FRONTAL PASSAGE TONIGHT COULD LEAD TO THE
DEVELOPMENT OF SOME LLWS LATE THIS EVENING AND CONTINUING OVERNIGHT.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...KAS
LONG TERM....GREIF
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1036 AM EST SAT DEC 15 2012
.SYNOPSIS...
LOW PRESSURE...FROM IOWA...MOVING NORTHEAST TO MICHIGAN...WILL
PUSH SHOWERS EASTWARD THROUGH THE UPPER OHIO VALLEY TONIGHT WITH A
FEW STRAGGLERS LEFT FOR SUNDAY. A SECOND LOW PRESSURE
SYSTEM...WILL DEVELOP NEAR ARKANSAS SUNDAY NIGHT...AND ALSO MOVE
NORTHEASTWARD TO PROVIDE US SHOWERS MONDAY INTO TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
PER RECENT RAP NAM AND SREF MODEL OUTPUT...HAVE MAINTAINED DRY
FORECAST FOR THE AFTERNOON. HAVE CONTINUED MENTION OF A GENERAL
CLOUD INCREASE THIS AFTERNOON BASED ON RECENT SURFACE AND
SATELLITE DATA.
FOR TONIGHT...CONCUR WITH RECENT SREF AND NAM MODEL OUTPUT THAT
LOW PRESSURE CENTER MOVING NORTHEASTWARD FROM IOWA TO MICHIGAN
WILL DEVELOP A LOWLEVEL JET ACROSS THE UPPER OHIO VALLEY TONIGHT.
THE RESULTING NORTHEAST SURGE OF LIFT AND MOISTURE WILL PUSH A BAND
OF SHOWERS EASTWARD THROUGH THE UPPER OHIO VALLEY EARLY TONIGHT.
CANNOT RULE OUT SOME ADDITIONAL SCATTERED SHOWERS LATE TONIGHT.
TWEAKED TEMPERATURES BASED ON RECENT HRRR AND GFS LAMP MODEL
OUTPUT...WHICH SHOW HIGHS THIS AFTERNOON 10 TO 15 DEGREES WARMER
THAN NORMAL. LOWS TONIGHT CAN BE 15 TO 20 DEGREES WARMER THAN
NORMAL AND ALL ABOVE FREEZING.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
LOW PRES WL MOVE NEWD INTO THE GREAT LAKES RGN BY THIS EVE...AND
DRIFT EWD INTO ERLY NEXT WEEK. ANOTHER LOW WL DVLP OVR THE MS VLY
RGN AND WORK NEWD MON INTO MON NT AS WELL. BACKED OFF ON POPS SUN
WITH MODELS SHOWING A LULL IN THE PRECIP. SHOWERS WL INCRS AGAIN
MON AS THE SECOND LOW APPROACHES. TEMPS WL CONTINUE TO BE WELL ABV
NORMAL THRU THE PD.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
OPERATIONAL MODELS AND ENSEMBLES ARE NOW IN DECENT AGREEMENT THROUGH
THE LONG TERM PD.
LOW PRES OVR PA ON TUE SHOULD BEGIN TO SHIFT EWD. SHOWERS SHOULD
TAPER OFF BY TUE EVE. COOLER AIR ON THE WRN SIDE OF THE LOW ALONG
WITH AN H5 WAVE COULD BRING A MIX OF RAIN AND SNOW SHOWERS TUE.
WED SHOULD BE MAINLY DRY WITH HIGH PRES BRIEFLY BUILDING IN. A
STRONG COLD FRONT WL MOVE E ACRS THE AREA THURSDAY NIGHT. THIS WL
USHER IN MUCH COLDER AIR. A SFC AND H5 LOW IS EXPECTED TO DRIFT
EWD ACRS THE LWR GREAT LAKES FRI...WITH A GOOD CHANCE OF SNOW
SHOWERS. WL MONITOR THIS FEATURE AS THE TIME NEARS. TEMPS SHOULD
REMAIN ABV NORMAL UNTIL THE STRONG COLD FRONT PASSES THROUGH
THURSDAY NIGHT. UNDERCUT GUIDANCE ON FRI WITH STG CAA EXPECTED.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
VFR CONDITIONS WILL CONTINUE ACROSS THE UPPER OHIO VALLEY THIS
AFTERNOON...AS RECENT SURFACE AND SATELLITE DATA SHOW NO LOWER
THAN ALTOCUMULUS CEILINGS HEADING TOWARD THE AREA.
WINDS WILL BE FROM THE SOUTH TO SOUTHEAST AT NO MORE THAN 10
KNOTS THIS AFTERNOON.
LOW PRESSURE MOVING ACROSS THE GREAT LAKES WILL PUSH A BAND OF
SHOWERS EASTWARD THROUGH THE UPPER OHIO VALLEY MAINLY EARLY
TONIGHT...WITH BRIEF MVFR RESTRICTIONS POSSIBLE.
.OUTLOOK.../SUNDAY THROUGH WEDNESDAY/...
POSSIBLE PERIODS OF RESTRICTIONS IN SHOWERS INTO WEDNESDAY...DUE
TO A SERIES OF LOW PRESSURE SYSTEMS CROSSING THE REGION INTO
TUESDAY...AND A POST SYSTEM COLD POOL WEDNESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
645 AM EST SAT DEC 15 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 442 AM EST SAT DEC 15 2012
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A SPLIT FLOW ACRS
NAMERICA WITH ZONAL NRN BRANCH OVER CANADA KEEPING THE REAL COLD
ARCTIC AIR LOCKED TO THE N OF THE BORDER. IN FACT...A LOOK AT THE
00Z H85 RAOBS SHOW TEMPS AT THAT LVL ABV 0C OVER ALL OF THE CONUS
EXCEPT THE NE AND PAC NW. EARLY THIS MRNG...THE UPR GRT LKS ARE
UNDER THE INFLUENCE OF A FAIRLY SHARP NRN BRANCH UPR RDG OVER
ONTARIO...AND LOCAL 00Z RAOBS SHOW A SHAPR SUBSIDENCE INVRN BASE
ARND H925 UNDER MID LVL DRY AIR. THE NEAR SFC LYR IS RATHER
MOIST...SO THERE IS QUITE A BIT OF LO CLD TRAPPED UNDER THIS INVRN.
TEMPS ARE GENERALLY WELL ABV NORMAL...IN THE 25 TO 30F RANGE. TO THE
SW...STRONG NEGATIVELY TILTED DISTURBANCE EMBEDDED IN THE WSW SRN
BRANCH FLOW IS LIFTING NEWD THRU THE CENTRAL PLAINS SUPPORTED BY
130KT H3 JET MAX OVER TX. ALTHOUGH THE MID LVLS OVER THE UPR LKS ARE
DRY...HI CLD WELL IN ADVANCE OF THIS SHRTWV IS SPILLING INTO THE
AREA. THE CLOSEST PCPN IN THE FORM OF RA AT 06Z HAS MOVED INTO
IA/NRN IL IN THE SURGE OF MSTR AHEAD OF THIS SHRTWV ENHANCED BY 50KT
H85 S LLJ OVER THE SRN PLAINS.
MAIN FCST CONCERNS IN THE SHORT TERM ARE MANY AND REVOLVE ARND
TIMING AND TYPE OF PCPN ASSOCIATED WITH DISTURBANCE MOVING NEWD THRU
THE PLAINS. ALTHOUGH NCEP INDICATES A PREFERENCE FOR THE 00Z GFS
GIVEN PRESENT NEGATIVE TILT OF THE DISTURBANCE/STRONG JET MAX
ROTATING NEWD ON ITS ERN FLANK...FCSTS SHOWING THIS DISTURBANCE
WEAKENING AS IT MOVES TOWARD THE NE WITH JET CORE SHEARING OUT THRU
THE GRT LKS INDICATE THE VERY CONSISTENT...FARTHER S 12Z ECMWF MIGHT
BE ON THE RIGHT TRACK. SO OPTED TO USE THE COMPROMISE 00Z NAM FOR
FCST DETAILS. OVERALL GIVEN ANTECEDENT DRY AIR ALF AND TRACK OF
STRONGER DYNAMICS TO THE SE...THIS PCPN EVENT WL NOT BE SGNFT.
TODAY...THIS MRNG SHOULD BE MAINLY PCPN FREE WITH LINGERING MID LVL
DRY AIR. THE ONLY CONCERN IS THE POTENTIAL FOR SOME -DZ/-FZDZ OVER
MAINLY THE CENTRAL ZNS WITH UPSLOPE ESE FLOW OFF LK MI AND THE
ARRIVAL OF BIT HIER H95-9 SPECIFIC HUMIDITY. DEEPER MSTR IS PROGGED
TO ARRIVE THIS AFTN...BUT MODELS REMAIN CONSISTENT SHOWING SHARPEST
H85-5 QVECTOR CNVGC PASSING TO THE SE AS DISTURBANCE WEAKENS AS IT
MOVES OUT OF THE SRN BRANCH TROF OVER THE DESERT SW. THE IMPRESSIVE
JET CORE IS ALSO FCST TO WEAKEN AND SHEAR OUT A BIT JUST S OF THE
LOWER LKS. IN FACT...MODEL QPF IS RATHER MODEST...WITH A BIT MORE
OVER THE SE CWA CLOSER TO THE SHARPER ISENTROPIC ASCENT/QVECTOR
CNVGC/UPR DVGC. TENDED TO CUT POPS FM PREVIOUS FCST A BIT ESPECIALLY
AWAY FM THE SE CWA TO REFLECT THE CONSENSUS ON THE TRACK OF BETTER
DYNAMIC SUPPORT. GIVEN THE WARMTH OF THE AIRMASS IN PLACE...SUSPECT
ANY PCPN WL AT LEAST START AS RA. BUT DRYNESS OF THE MID LVLS AND
POTENTIAL EVAP COOLING MIGHT CAUSE SOME OF THIS PCPN TO AT LEAST MIX
WITH SN...ESPECIALLY OVER THE HIER TERRAIN OF THE CENTRAL. BUT THE
LACK OF SGNFT DYNAMIC FORCING/OMEGA SUGS THIS PROCESS WL NOT BE AS
VIGOROUS AS MIGHT OTRW BE THE CASE. WITH THE SFC LO WEAKENING AS IT
MOVES TO THE NE...TENDED TOWARD THE LOWER SIDE OF GUIDANCE FOR
TEMPS...WHICH IS IN GOOD AGREEMENT WITH PREVIOUS FCST.
TONIGHT...MAIN DISTURBANCE PASSING TO THE SE IS FCST TO SHIFT AWAY
TO THE E...SO SUSPECT PCPN OVER MUCH OF THE CWA WL DIMINISH TO JUST
A BIT OF -RA/-SN PERHAPS -DZ/-FZDZ AFTER 00Z AS GUIDANCE SHOWS
LARGER SCALE QVECTOR DVGC IN PLACE THIS EVNG. ADDED MENTION OF FOG
IN UPSLOPING AREAS OVER MAINLY THE CENTRAL IN LLVL SE FLOW WITH
LINGERING LLVL MSTR UNDER SOME UPR DRYING. BUT SHRTWV EMBEDDED IN
NRN BRANCH IS PROGGED TO BRING A RETURN OF SOME LARGER SCALE QVECTOR
CNVGC/UPR DVGC LATER OVER THE W...SO TRENDED POPS HIER THERE OVERNGT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 442 AM EST SAT DEC 15 2012
SUNDAY...THE MODELS ARE VERY SIMILAR WITH THE OVERALL
PATTERN...INDICATING A LINGERING MID/UPPER LEVEL TROUGH OVER THE
NORTHERN GREAT LAKES AND A DOWNSTREAM BLOCKING RIDGE OVER QUEBEC.
THERE ARE MORE SUBTLE DIFFERENCES WITH THE WEAK SHORTWAVES MOVING
THROUGH NRN WI AND UPPER MI THAT MAY ENHANCE ANY PCPN. WITH
RELATIVELY ABUNDANT MOISTURE IN PLACE OVER THE AREA...THE WEAK TO
MODERATE QVECTOR CONV AND POTENTIAL FOR 800-600 MB FGEN (ESPECIALLY
OVER THE WEST PER NAM) THE FORECAST KEEPS LIKELY POPS GOING BUT FOR
LIGHT QPF...LESS THAN A TENTH OF AN INCH. AT THE SFC...A TROUGH WILL
WILL LINGER OVER UPPER MI...RESULTING IN A RELATIVELY WARM LOW LEVEL
TEMP PROFILE. USING A GFS/NAM/ECMWF COMPROMISE ON LOW LEVEL
TEMPS...EXPECT MAINLY SNOW OVER THE WEST BUT A RAIN/SNOW MIX EAST AND
MAINLY RAIN NEAR LAKE MICHIGAN.
SUNDAY NIGHT INTO MONDAY...THE MORE WIDESPREAD PCPN SHOULD DIMINISH
SUNDAY NIGHT AS THE MID LEVEL AND SFC TROUGHS LIFT TO THE NORTHEAST.
COLDER AIR WILL THEN FILTER INTO THE AREA BRINGING 850 MB TEMPS DOWN
TO NEAR -6C. THE COLD AIR COMBINED WITH MOIST CYCLONIC LOW LEVEL
FLOW MAY SUPPORT SOME LIGHT LAKE ENHANCED SNOW OVER THE NORTH. THE
GREATEST POTENTIAL FOR ANY ACCUMULATING SNOW IS LIKELY OVER THE WEST
WHERE THE ONSHORE FLOW WOULD BE A BIT STRONGER COMPARED TO THE EAST
WHERE ONLY LIGHT WINDS PREVAIL UNDER THE INFLUENCE OF LAKE INDUCED
TROUGHING.
TUE-FRI...MODELS WERE SIMILAR WITH TREND TOWARD A PROGRESSIVE
PATTERN WHICH WILL BRING A MID/UPPER LEVEL TROUGH INTO THE WRN CONUS
TUE AND INTO THE PLAINS BY WED NIGHT. MID LEVEL AND SFC RIDGING
AHEAD OF THIS FEATURE WILL RESULT IN DRY WEATHER WITH TEMPS NEAR OR
SLIGHTLY ABOVE SEASONAL AVERAGES. THERE IS THE POTENTIAL FOR A
SIGNIFICANT STORM SYSTEM BY THU INTO FRI MOVING OUT OF THE PLAINS
TOWARD THE GREAT LAKES. THE GFS/ECMWF BRING THE SFC LOW INTO THE SRN
LAKES WITH POTENTIAL FOR SNOW AND LAKE ENHANCED SNOW OVER UPPER MI.
AS WOULD BE EXPECTED FOR A FORECAST FOR DAYS 5/6... THERE IS STILL
CONSIDERABLE UNCERTAINTY WITH THE PATH AND STRENGTH OF THE SYSTEM.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 636 AM EST SAT DEC 15 2012
ALTHOUGH THERE MAY BE SOME VFR INTERVALS AT CMX/IWD WITH DOWNSLOPE
SE WIND JUST ABV THE SFC THIS MRNG...IFR/LIFR CONDITIONS WL
PREDOMINATE THIS FCST PERIOD WITH GRADUAL INFLUX OF DEEPER MSTR AND
THE ARRIVAL OF SOME -RASN THIS AFTN ON THE N FLANK OF LO PRES MOVING
TOWARD THE GREAT LKS. VLIFR CONDITIONS MAY OCCUR AT CMX/SAW TNGT
WITH DIMINISHING WINDS UNDER DRYING ALOFT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 442 AM EST SAT DEC 15 2012
AS LO PRES APPROACHES FROM THE SW...TIGHTENING GRADIENT WILL SUPPORT
AN INCREASING SE WIND INTO TONIGHT. AFTER COORDINATION WITH
ENVIRONMENT CANADA...OPTED TO ISSUE A GALE WARNING FOR THE FAR E...
WHERE THE GRADIENT IS EXPECTED TO BE TIGHTEST AND TERRAIN OFTEN
ACCENTUATES A SE FLOW. OVER THE W WHERE THE GRADIENT WILL BE
WEAKER...WIND SHOULD REMAIN UNDER 25 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING FROM 6 PM THIS EVENING TO 4 AM EST SUNDAY FOR
LSZ267.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...JLB
AVIATION...KC
MARINE...KC
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
656 AM CST SAT DEC 15 2012
.UPDATE...FOR 12Z AVIATION DISCUSSION BELOW
&&
.DISCUSSION.../ISSUED 406 AM CST SAT DEC 15 2012/
WILL START WITH MAIN CHANGES THAT HAVE COME ABOUT WITH THIS
FORECAST PACKAGE. FIRST...AS OF 3 AM...ALL BUT MADISON AND
APPLETON IN WRN MN HAVE RISEN ABOVE FREEZING...SO THE THREAT FOR
FREEZING RAIN IS NOW LOOKING MINIMAL. SECOND CHANGE...DEFORMATION
PRECIP WEST OF THE LOW TRACK IS LOOKING TO BE MUCH MORE ROBUST
ACROSS WRN MN THIS AFTERNOON AND WORKING ACROSS CENTRAL MN
TONIGHT. BOOSTED SNOW AMOUNTS SOME...WITH 4 INCHES NOW FORECAST UP
IN THE NW CWA...THOUGH DEPENDING ON HOW QUICKLY TRANSITION TO SNOW
OCCURS...THIS COULD END UP BEING MORE. OTHER IMPACT OF THE
DEFORMATION PRECIP IS THAT HEAVIER SNOW IS NOW EXPECTED FROM THIS
AFTERNOON INTO TONIGHT...SO EXTENDED WINTER WEATHER ADVY OUT IN
TIME TO 00Z FOR WEST CENTRAL MN AND 06Z TONIGHT FOR CENTRAL MN
OVER TO POLK COUNTY WI.
INTERESTING WATER VAPOR IMAGERY THIS MORNING WITH TWO BAROCLINIC
LEAF STRUCTURES SEEN MOVING NE ACROSS THE PLAINS. ONE IS MOVING
FROM CENTRAL NEB INTO CENTRAL SODAK. THIS HAS BEEN INITIALIZED
POORLY BY ALL BUT THE RAP...BUT ALL THIS WAVE LOOKS TO DO IS
EXPAND PRECIPITATION SHIELD A LITTLE FARTHER NW. THE MAIN WAVE CAN
BE SEEN OVER KC...WITH A STRONG PV ANOMALY AND MID LEVEL DRYING
SEEN WITH IT. THIS UPPER WAVE WILL HEAD TOWARD CENTRAL WI AND WILL
HELP DRIVE A SFC LOW FROM KC...UP TO ROCHESTER THEN OVER TO GREEN
BAY. SEEING A NICE TROWAL SIGNATURE WITH THIS WAVE AS WELL...WITH
THE RAP BRINGING THE 1.5 PV SFC DOWN TO ABOUT H5. THIS TROWAL WILL
HELP ENHANCE THE DEFORMATION PRECIP EXPECTED TO MOVE UP INTO WRN
MN...THEN EAST ACROSS CENTRAL MN.
15.06 NAM ALONG WITH THE 15.00 ECMWF LOOK TO HAVE BEST HANDEL ON
DEFORMATION PRECIP BAND CURRENTLY ACROSS ERN NEB...SO FAVORED QPF
AND POP FORECAST INTO TONIGHT HEAVILY ON A BLEND OF THESE TWO
MODELS. FOR SNOWFALL AMOUNTS...IT WILL DEPEND HEAVILY ON HOW
QUICKLY CHANGE OVER TO SNOW OCCURS. FAVOR AN ECMWF NMM/ARW WRF
DEPICTION...WHICH SHOW PRIMARILY RAIN THROUGH 18Z...WITH A
TRANSITION TO MOSTLY SNOW BY 00Z NW OF A GRANITE FALLS TO LITTLE
FALLS LINE...WITH TRANSITION TO SNOW SLOWLY WORKING ACROSS THE CWA
THERE AFTER. AT THE MOMENT HAVE 2-4 INCHES NORTHWEST OF A GRANITE
FALLS TO MORA LINE. THOUGH AS STATED ABOVE..THE EARLIER THE
TRANSITION OCCURS...THE MORE ACCUMULATIONS WOULD OCCUR AND WOULD
NOT COMPLETELY RULE OUT SEEING WARNING TYPE SNOW /6 INCHES OR
MORE/ FROM ALEX OVER TOWARD MORA.
OF COURSE ONE SILVER LINING IN ALL OF THIS...IS THE ENTIRE CWA
LOOKS TO RECEIVE AT LEAST A QUARTER INCH OF QPF...WITH POSSIBLY
MORE THAN A HALF INCH ACROSS WRN MN WITH DEFORMATION BAND AND WRN
WI...WHICH WILL BE CLOSER TO THE LLJ HEADING FOR CENTRAL WI. THIS
WOULD PUT JUST ABOUT ALL LOCATIONS ACROSS THE CWA ABOVE NORMAL ON
LIQUID PRECIPITATION FOR THE MONTH...WHICH WOULD BE THE FIRST TIME
MOST PLACES ACROSS THE MPX AREA WOULD HAVE DONE THAT SINCE MAY OR
JUNE OF THIS YEAR.
BEHIND THIS SYSTEM...THE WEATHER LOOKS DRY AND TRANQUIL FROM
MONDAY THROUGH WEDNESDAY...WITH TEMPERATURES NEAR NORMAL. ONLY
OUTSIDE SHOT AT SOME LIGHT SNOW WOULD COME TUESDAY AS A WEAK WARM
FRONT LIFTS NE INTO THE AREA BEFORE WASHING OUT.
OF MORE CONCERN NEXT WEEK IS WHAT LOOKS TO BE A MAJOR WINTER STORM
THAT WILL BE PLAYING OUT ACROSS THE CENTER OF THE COUNTRY. THE
ECMWF/GFS/FIM ARE ALL IN REMARKABLY GOOD AGREEMENT WITH THIS
SYSTEM FOR 5/6 DAYS OUT...SHOWING A DEEP SFC LOW TRACKING FROM
CENTRAL MO WEDNESDAY NIGHT OVER TOWARD MICHIANA BY THU AFTERNOON.
THIS WOULD KEEP THE MAJORITY OF PRECIPITATION SOUTH OF THE MPX
CWA...WITH MAINLY THE SE CWA HAVING THE BEST CHANCE AT GETTING
BUZZED BY A COUPLE OF INCHES OF SNOW. GIVEN MODEL AGREEMENT...DID
PUT SOME LIKELY SNOWS IN FOR THE SE CWA. OF MORE CONCERN...
ESPECIALLY WITH THE VERY SIMILAR FIM/ECMWF IS THE SIGNIFICANT
BLIZZARD BOTH TAKE FROM NRN MO/IA...ACROSS NRN IL/SRN WI INTO WRN
MI WEDNESDAY NIGHT/THURSDAY. IF ANY SORT OF NRN SHIFT IS SEEN IN
THE MODELS IN THE COMING DAYS...THEN PARTS OF THE MPX CWA MAY VERY
WELL HAVE TO DEAL WITH WHAT IS CERTAINLY LOOKING TO BE A VERY
SIGNIFICANT WINTER STORM.
BEHIND THIS SYSTEM...WE LOOK TO END THE WEEK ON A COLD NOTE. IN
FACT THE GFS/ECMWF ARE HINTING AT THE WX PATTERN TAKING A TURN FOR
THE SIGNIFICANTLY COLDER AS WE HEAD TOWARD CHRISTMAS...WITH DEEP
TROUGHING ALONG THE EAST COAST AND SHARP RIDGING OVER THE ROCKIES.
THIS WOULD HELP DISLODGE THE BITTERLY COLD AIR THAT HAS BEEN
LOCKED UP AND BUILDING UP OVER AK/CANADA THE LAST SEVERAL WEEKS.
&&
.AVIATION.../12Z TAF ISSUANCE/
WITH SURFACE TEMPERATURES JUST ABOVE FREEZING AT THE TAF SITES
THIS MORNING...THE BLOB OF PRECIPITATION LIFTING NORTH INTO THE
AREA FROM IOWA IS LESS DAUNTING AS FAR AS PRECIPITATION TYPES ARE
CONCERNED. EXPECT RAIN TO PREVAIL THIS MORNING...WITH CIGS BETWEEN
500 AND 1500 FT. VSBYS WITH THE RAIN WILL GENERALLY RANGE BETWEEN
1 AND 3 SM. RAIN WILL MIX WITH SNOW THIS AFTERNOON /CLOSER TO 16Z
AT KAXN/...AND THEN CHANGE OVER TO SNOW BETWEEN 00Z AND 06Z /22Z
AT KAXN/. CONFIDENCE IN CHANGEOVER TIMING IS NOT EXTREMELY
HIGH...AS THE LATEST RUN OF THE GFS IS WARMER AND FEATURES HARDLY
ANY SNOW BEFORE THE PRECIP SHUTS OFF. WHILE WE COULD SEE MINOR
IMPROVEMENT TO CIGS AS THE SNOW COMES TO AN END EARLY SUNDAY
MORNING...REALLY EXPECT CIGS TO STAY BELOW 2KFT THROUGH THE
PERIOD.
KMSP...
HIGH CONFIDENCE IN RAIN TODAY AND IFR CIGS/VSBYS. EXPECT RAIN TO
MIX WITH SNOW AROUND 00Z...AND THEN EVENTUALLY TRANSITION TO SNOW
BY 03Z. OPPORTUNITY TO IMPROVE TO MVFR VSBYS AROUND/AFTER
05Z...BUT NOT TO MVFR CIGS UNTIL CLOSER TO 12Z SUNDAY. SOUTHEAST
WINDS AROUND 10 KTS TODAY...THEN SHIFTING TO THE NORTHWEST BETWEEN
23Z AND 02Z.
/OUTLOOK FOR KMSP/
SUN...IFR/MVFR CONDS EARLY...SLOW IMPROVEMENT DURING THE DAY.
CHC -SN EARLY. NW WIND 5-10 KTS.
MON...PREVAILING VFR CONDS EXPECTED...POSSIBLE MVFR CEILINGS. NW
WIND AROUND 5 KTS.
TUE...MVFR CIGS POSSIBLE EARLY. S WINDS AROUND 5 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR BENTON-
CHISAGO-DOUGLAS-ISANTI-KANABEC-MILLE LACS-MORRISON-POPE-
SHERBURNE-STEARNS-STEVENS-TODD.
ICE STORM WARNING UNTIL 6 PM CST THIS EVENING FOR LAC QUI PARLE-
YELLOW MEDICINE.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR CHIPPEWA-
KANDIYOHI-SWIFT.
WI...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR POLK.
&&
$$
MPG/LS
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
406 AM CST SAT DEC 15 2012
.DISCUSSION...
WILL START WITH MAIN CHANGES THAT HAVE COME ABOUT WITH THIS
FORECAST PACKAGE. FIRST...AS OF 3 AM...ALL BUT MADISON AND
APPLETON IN WRN MN HAVE RISEN ABOVE FREEZING...SO THE THREAT FOR
FREEZING RAIN IS NOW LOOKING MINIMAL. SECOND CHANGE...DEFORMATION
PRECIP WEST OF THE LOW TRACK IS LOOKING TO BE MUCH MORE ROBUST
ACROSS WRN MN THIS AFTERNOON AND WORKING ACROSS CENTRAL MN
TONIGHT. BOOSTED SNOW AMOUNTS SOME...WITH 4 INCHES NOW FORECAST UP
IN THE NW CWA...THOUGH DEPENDING ON HOW QUICKLY TRANSITION TO SNOW
OCCURS...THIS COULD END UP BEING MORE. OTHER IMPACT OF THE
DEFORMATION PRECIP IS THAT HEAVIER SNOW IS NOW EXPECTED FROM THIS
AFTERNOON INTO TONIGHT...SO EXTENDED WINTER WEATHER ADVY OUT IN
TIME TO 00Z FOR WEST CENTRAL MN AND 06Z TONIGHT FOR CENTRAL MN
OVER TO POLK COUNTY WI.
INTERESTING WATER VAPOR IMAGERY THIS MORNING WITH TWO BAROCLINIC
LEAF STRUCTURES SEEN MOVING NE ACROSS THE PLAINS. ONE IS MOVING
FROM CENTRAL NEB INTO CENTRAL SODAK. THIS HAS BEEN INITIALIZED
POORLY BY ALL BUT THE RAP...BUT ALL THIS WAVE LOOKS TO DO IS
EXPAND PRECIPITATION SHIELD A LITTLE FARTHER NW. THE MAIN WAVE CAN
BE SEEN OVER KC...WITH A STRONG PV ANOMALY AND MID LEVEL DRYING
SEEN WITH IT. THIS UPPER WAVE WILL HEAD TOWARD CENTRAL WI AND WILL
HELP DRIVE A SFC LOW FROM KC...UP TO ROCHESTER THEN OVER TO GREEN
BAY. SEEING A NICE TROWAL SIGNATURE WITH THIS WAVE AS WELL...WITH
THE RAP BRINGING THE 1.5 PV SFC DOWN TO ABOUT H5. THIS TROWAL WILL
HELP ENHANCE THE DEFORMATION PRECIP EXPECTED TO MOVE UP INTO WRN
MN...THEN EAST ACROSS CENTRAL MN.
15.06 NAM ALONG WITH THE 15.00 ECMWF LOOK TO HAVE BEST HANDEL ON
DEFORMATION PRECIP BAND CURRENTLY ACROSS ERN NEB...SO FAVORED QPF
AND POP FORECAST INTO TONIGHT HEAVILY ON A BLEND OF THESE TWO
MODELS. FOR SNOWFALL AMOUNTS...IT WILL DEPEND HEAVILY ON HOW
QUICKLY CHANGE OVER TO SNOW OCCURS. FAVOR AN ECMWF NMM/ARW WRF
DEPICTION...WHICH SHOW PRIMARILY RAIN THROUGH 18Z...WITH A
TRANSITION TO MOSTLY SNOW BY 00Z NW OF A GRANITE FALLS TO LITTLE
FALLS LINE...WITH TRANSITION TO SNOW SLOWLY WORKING ACROSS THE CWA
THERE AFTER. AT THE MOMENT HAVE 2-4 INCHES NORTHWEST OF A GRANITE
FALLS TO MORA LINE. THOUGH AS STATED ABOVE..THE EARLIER THE
TRANSITION OCCURS...THE MORE ACCUMULATIONS WOULD OCCUR AND WOULD
NOT COMPLETELY RULE OUT SEEING WARNING TYPE SNOW /6 INCHES OR
MORE/ FROM ALEX OVER TOWARD MORA.
OF COURSE ONE SILVER LINING IN ALL OF THIS...IS THE ENTIRE CWA
LOOKS TO RECEIVE AT LEAST A QUARTER INCH OF QPF...WITH POSSIBLY
MORE THAN A HALF INCH ACROSS WRN MN WITH DEFORMATION BAND AND WRN
WI...WHICH WILL BE CLOSER TO THE LLJ HEADING FOR CENTRAL WI. THIS
WOULD PUT JUST ABOUT ALL LOCATIONS ACROSS THE CWA ABOVE NORMAL ON
LIQUID PRECIPITATION FOR THE MONTH...WHICH WOULD BE THE FIRST TIME
MOST PLACES ACROSS THE MPX AREA WOULD HAVE DONE THAT SINCE MAY OR
JUNE OF THIS YEAR.
BEHIND THIS SYSTEM...THE WEATHER LOOKS DRY AND TRANQUIL FROM
MONDAY THROUGH WEDNESDAY...WITH TEMPERATURES NEAR NORMAL. ONLY
OUTSIDE SHOT AT SOME LIGHT SNOW WOULD COME TUESDAY AS A WEAK WARM
FRONT LIFTS NE INTO THE AREA BEFORE WASHING OUT.
OF MORE CONCERN NEXT WEEK IS WHAT LOOKS TO BE A MAJOR WINTER STORM
THAT WILL BE PLAYING OUT ACROSS THE CENTER OF THE COUNTRY. THE
ECMWF/GFS/FIM ARE ALL IN REMARKABLY GOOD AGREEMENT WITH THIS
SYSTEM FOR 5/6 DAYS OUT...SHOWING A DEEP SFC LOW TRACKING FROM
CENTRAL MO WEDNESDAY NIGHT OVER TOWARD MICHIANA BY THU AFTERNOON.
THIS WOULD KEEP THE MAJORITY OF PRECIPITATION SOUTH OF THE MPX
CWA...WITH MAINLY THE SE CWA HAVING THE BEST CHANCE AT GETTING
BUZZED BY A COUPLE OF INCHES OF SNOW. GIVEN MODEL AGREEMENT...DID
PUT SOME LIKELY SNOWS IN FOR THE SE CWA. OF MORE CONCERN...
ESPECIALLY WITH THE VERY SIMILAR FIM/ECMWF IS THE SIGNIFICANT
BLIZZARD BOTH TAKE FROM NRN MO/IA...ACROSS NRN IL/SRN WI INTO WRN
MI WEDNESDAY NIGHT/THURSDAY. IF ANY SORT OF NRN SHIFT IS SEEN IN
THE MODELS IN THE COMING DAYS...THEN PARTS OF THE MPX CWA MAY VERY
WELL HAVE TO DEAL WITH WHAT IS CERTAINLY LOOKING TO BE A VERY
SIGNIFICANT WINTER STORM.
BEHIND THIS SYSTEM...WE LOOK TO END THE WEEK ON A COLD NOTE. IN
FACT THE GFS/ECMWF ARE HINTING AT THE WX PATTERN TAKING A TURN FOR
THE SIGNIFICANTLY COLDER AS WE HEAD TOWARD CHRISTMAS...WITH DEEP
TROUGHING ALONG THE EAST COAST AND SHARP RIDGING OVER THE ROCKIES.
THIS WOULD HELP DISLODGE THE BITTERLY COLD AIR THAT HAS BEEN
LOCKED UP AND BUILDING UP OVER AK/CANADA THE LAST SEVERAL WEEKS.
&&
.AVIATION.../06Z TAF ISSUANCE/
SEE THE EARLIER UPDATE ABOVE FOR ADDITIONAL INFORMATION ON THE
LATEST TRENDS. NO SIGNIFICANT CHANGES TO THE 00Z TAF EXCEPT FOR
SOME MINOR TIMING CHANGES. THINK WE WILL BE WARM ENOUGH FOR ALL RAIN
AT KRWF/KMSP/KRNH/KEAU FOR MOST OF THE EVENT UNTIL A TRANSITION TO
SNOW SATURDAY AFTERNOON/EVENING. KSTC IS ON THE BORDER FOR
RAIN/FREEZING RAIN...AND KAXN SHOULD BE COLD ENOUGH FOR ICING
PROBLEMS TOMORROW MORNING. KAXN CAN ONLY HOPE THE TEMP EVENTUALLY
WARMS TO 33/34 SO THE FREEZING RAIN DOESN`T GET OUT OF HAND. THE
TEMP IS 28 EARLY THIS MORNING. SLOWLY BRING CEILINGS DOWN AS
RAIN/MIST BECOMES HEAVIER BY MID MORNING. VIS IS LOWERED AS PRECIP
TRANSITION TO SNOW. OVERALL...PLENTY OF IFR TODAY EVERYWHERE.
KMSP...
TRIED TO GIVE THE WINDS A LITTLE BETTER PRECISION THIS
AFTERNOON...AS WELL AS ADJUST THE START AND END TIMES OF RAIN AND
SNOW. HIGH CONFIDENCE NOW IN JUST PLAIN RAIN UNTIL THIS AFTERNOON
WHEN A TRANSITION TO SNOW IS EXPECTED. AIRPORT IS AT 37 DEGREES
EARLY THIS MORNING...AND COULD ACTUALLY CLIMB A COUPLE MORE
DEGREES BY THE TIME THE MODERATE RAIN BEGINS MID MORNING. THERE
WILL BE IFR VIS/CIG RESTRICTIONS TODAY. HIGH CONFIDENCE IN THAT AS
WELL.
/OUTLOOK FOR KMSP/
SUN...IFR/MVFR CONDS EARLY...SLOW IMPROVEMENT DURING THE DAY.
CHC -SN EARLY. NW WIND 5-10 KT.
MON...PREVAILING VFR CONDS EXPECTED...POSSIBLE MVFR CEILINGS. NW
WIND AROUND 5 KT.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR BENTON-
CHISAGO-DOUGLAS-ISANTI-KANABEC-MILLE LACS-MORRISON-POPE-
SHERBURNE-STEARNS-STEVENS-TODD.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR CHIPPEWA-
KANDIYOHI-LAC QUI PARLE-SWIFT-YELLOW MEDICINE.
WI...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR POLK.
&&
$$
MPG/CLF
AREA FORECAST DISCUSSION
NWS BISMARCK ND
630 AM CST SAT DEC 15 2012
.SHORT TERM...BAND OF MIXED PRECIPITATION EXTENDS FROM CENTRAL
SOUTH DAKOTA...NORTHEAST THROUGH THE FAR SOUTHEAST CORNER OF NORTH
DAKOTA AND INTO MINNESOTA. HRRR STILL SHOWS SOME OF THIS
PRECIPITATION TOUCHING TWO OF MY SOUTHEAST COUNTIES THOUGH RADAR
LOOPS SEEEM TO BE PULLING SLIGHTLY EAST OF THE AREA. TOO CLOSE TO
REMOVE POPS FOR NOW. A FEW LINGERING QUARTER MILE VISIBILITIES FAR
NORTH CENTRAL BUT NOT WIDESPREAD ENOUGH FOR AN ADVISORY.
.AVIATION...
12Z TAFS SHOW A TREND OF DECREASING CLOUDS AND INCREASING
VISIBILITY AS WEAK SURFACE TROUGH PASSAGE TURNS WINDS NORTH AND
WEST. ALL BUT KJMS SHOULD BE VFR BY 18Z.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...HW
AVIATION...HW
AREA FORECAST DISCUSSION
NWS PUEBLO CO
254 PM MST SAT DEC 15 2012
.SHORT TERM...
(TONIGHT AND SUNDAY)
...ROUNDS OF SNOW TO CONTINUE ALONG THE CONTINENTAL DIVIDE...
NEXT UPPER TROF ALREADY MOVING THROUGH UT TOWARDS THE 4 CORNERS
REGION AND WILL BE MOVING ACROSS SRN CO TONIGHT. STARTING TO SEE
SOME ENHANCEMENT AHEAD OF THIS FEATURE ACROSS SW UT...AND SUSPECT
THAT SNOW WILL BE PICKING UP AGAIN ACROSS THE WOLF CREEK PASS AREA
BY LATE AFTERNOON. ITS BEEN SNOWING MAJORITY OF THE DAY ALONG THE
CONTDVD...BUT BASED ON WEB CAMS AT WOLF CREEK SKI AREA AND CDOT WEB
CAMS...IT DOESN`T APPEAR AS HEAVY AS YESTERDAY. LATEST NAM12 HAS
COME IN A BIT HEAVIER WITH SNOWFALL AMOUNTS DURING THE EVENING WHEN
BRUNT OF FORCING AND DEEPER MOISTURE MOVES IN. WILL ALSO HAVE SOME
INSTABILITY TO PLAY WITH. ALL IN ALL...STILL LOOKS LIKE A SOLID
ADVISORY EVENT FOR THE EASTERN SAN JUANS WITH SNOWFALL TOTALS
RANGING FROM 5 TO 10 INCHES WITH LOCALLY UP TO A FOOT FOR THE
PEAKS. HAVE OPTED TO EXTEND THE WINTER WEATHER ADVISORY FOR ZONE 68
THROUGH 07Z...AS LATEST RUNS APPEAR A LITTLE SLOWER WITH THE
SYSTEM.
FOR THE REMAINDER OF THE REGION...HAVE ALREADY HAD ONE WAVE OF
UPGLIDE LIFT OFF TO THE NORTHEAST OF THE AREA. THIS BROUGHT SOME
ISOLATED LIGHT SHOWERS TO THE PIKES PEAK REGION RIGHT AROUND THE
NOON HOUR. AS THE NEXT WAVE APPROACHES...EXPECT ANOTHER ROUND TO
SPREAD IN DURING THE EVENING HOURS. DON`T THINK IT WILL AMOUNT TO
MUCH EAST OF THE MTS...BUT SOME AREAS ALONG MONUMENT HILL COULD PICK
UP SOME LIGHT ACCUMS RANGING FROM A TRACE TO AN INCH.
INTERESTINGLY...THE 18Z NAM HAS BACKED OFF ON SNOWFALL FOR THIS
REGION...HOWEVER RUC13 HANDLED THE EARLIER WAVE OF LIGHT SNOW
BETTER...SO WILL LEAN TOWARDS ITS SOLN AND MAINTAIN ISOLATED POPS
(SCATTERED ACROSS TELLER COUNTY/NRN EL PASO) THROUGH THE EVENING.
RUC HAS THE NEXT WAVE OF PRECIP MOVING INTO THIS AREA AROUND 01Z.
SHOULD ALSO SEE ANOTHER ROUND OF SNOW SPREAD ACROSS THE SAN LUIS
VALLEY AND INTO THE SANGRE DE CRISTO MOUNTAINS BETWEEN 03Z AND 09Z.
HAVE INCREASED POPS ACROSS THESE AREAS TO ACCOUNT FOR THIS.
ADDITIONAL ACCUMULATIONS OF 1 TO 4 INCHES WILL BE POSSIBLE FOR THE
HIGHER PEAKS. MOST OF THE SAN LUIS VALLEY SHOULD SEE LESS THAN AN
INCH...BUT SOME AREAS COULD SEE SLIGHTLY MORE...ESPECIALLY AGAINST
THE WEST SLOPES OF THE SANGRES...NEAR CRESTONE.
SYSTEM WILL EXIT EASTERN COLORADO BY EARLY SUNDAY MORNING. LIGHT
SNOW CONTINUES ALONG THE CONTINENTAL DIVIDE THROUGH THE DAY...BUT AM
ONLY GETTING ANOTHER INCH OR TWO OF ACCUMS...WHICH IS NOT ENOUGH TO
WARRANT ANY FURTHER HEADLINES AT THIS POINT. OTHERWISE...WEST TO
NORTHWEST WINDS BEHIND THE DEPARTING SYSTEM SHOULD HELP BOOST TEMPS
TO NEAR CLIMATOLOGICAL NORMALS. HAVE GONE ON THE COLDER SIDE OF
GUIDANCE FOR THE SAN LUIS VALLEY DUE TO SNOW COVER. -KT
.LONG TERM...
(SUNDAY NIGHT THROUGH NEXT SATURDAY)
LONGER TERM METEOROLOGICAL CHALLENGES INCLUDE POPS...TEMPERATURES
AND GUSTY WINDS AT TIMES. RELATIVELY MOIST NORTHWESTERLY TO ZONAL
UPPER FLOW OVER THE FORECAST DISTRICT FROM SUNDAY NIGHT INTO
TUESDAY WILL ALLOW SNOW TO BE NOTED AT TIMES OVER THE SAN JUAN AND
ESPECIALLY THE CENTRAL MOUNTAINS.
AT THIS TIME...HAVE DEPICTED PERSISTENT RELATIVELY LIGHT SNOW OVER
THE CENTRAL MOUNTAINS FROM SUNDAY NIGHT INTO TUESDAY WITH INDIVIDUAL
6 HOUR SNOW AMOUNTS RARELY OVER 2 INCHES. ELSEWHERE...PROJECT THAT
BASICALLY DRY CONDITIONS WILL BE THE RULE FROM SUNDAY NIGHT INTO
TUESDAY.
FROM TUESDAY NIGHT INTO WEDNESDAY EVENING...A STRONGER UPPER WAVE
MOVES ACROSS THE FORECAST DISTRICT. THIS SYSTEM IS EXPECTED TO
ENHANCE PRECIPITATION CHANCES...GENERATE GUSTY WINDS AND PRODUCE
COOLER TEMPERATURES DURING THIS PERIOD. HAVE ADJUSTED LATEST GRIDS
AND ZONES TO REFLECT THIS TREND.
DRY UPPER RIDGING THEN BUILDING OVER SOUTHERN COLORADO FROM LATER
WEDNESDAY NIGHT INTO FRIDAY WILL ALLOW WARMER AND DRIER CONDITIONS
TO RETURN TO THE FORECAST DISTRICT WITH GRADUALLY INCREASINGLY
MOIST SOUTHWESTERLY UPPER FLOW THEN IMPINGING ON THE CWFAS WESTERN
MOUNTAINS BY NEXT SATURDAY.
WARMEST CONDITIONS OF THE LONGER TERM ARE IN STORE MONDAY AND
TUESDAY AND THEN AGAIN FRIDAY...WHILE COOLEST TEMPERATURES ARE
ANTICIPATED FROM WEDNESDAY INTO WEDNESDAY NIGHT. FINALLY...THE
STRONGEST WINDS OF THE LONGER TERM SHOULD BE NOTED AT TIMES FROM
LATER MONDAY NIGHT INTO THURSDAY...ESPECIALLY OVER EASTERN
PORTIONS OF THE FORECAST DISTRICT.
&&
.AVIATION...
ANOTHER ROUND OF HEAVIER SNOW SHOULD MOVE INTO THE SOUTHWEST AND
CENTRAL MOUNTAINS THIS EVENING. MTN OBSCURATIONS WILL CONTINUE WITH
IFR/LIFR VIS AND CIGS IN SHSN. GENERALLY VFR CONDITIONS EXPECTED AT
KCOS AND KPUB THROUGH THE NEXT 24 HOURS...THOUGH -SHSN WILL BE
POSSIBLE AT KCOS DURING THE EVENING AS THE NEXT SYSTEM APPROACHES.
CIGS WITH -SHSN COULD DROP INTO THE MVFR CATEGORY BRIEFLY...THOUGH
ANY ACCUMS SHOULD REMAIN UNDER AN INCH AND MOST LIKELY TO OCCUR TO
THE NORTH OF THE KCOS TERMINAL. KALS COULD ALSO SEE SOME MVFR TO
BRIEF IFR CIGS WITH -SHSN AFTER 01-02Z...WITH ADDITIONAL LIGHT SNOWFALL
ACCUMULATIONS OF UP TO AN INCH POSSIBLE. VFR CONDITIONS WILL
RETURN TO ALL TAF SITES BY EARLY SUNDAY MORNING AS THE SYSTEM PASSES
TO THE EAST OF THE REGION. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST TONIGHT FOR COZ068.
&&
$$
AREA FORECAST DISCUSSION
NWS MIAMI FL
238 PM EST SAT DEC 15 2012
.DISCUSSION...
SCATTERED SHOWERS CONTINUE TO STREAM INTO SOUTH FLORIDA UNDER A
CONTINUED MID LEVEL INVERSION AND EAST-NORTHEASTERLY SURFACE FLOW.
LATEST HRRR DEPICTS SHOWERS DIMINISHING IN COVERAGE THROUGH THE
EVENING AND OVERNIGHT HOURS AS UPPER RIDGING BEGINS TO BUILD
ACROSS THE AREA FROM THE GULF OF MEXICO. AS RIDGING BUILDS
IN...WINDS WILL BEGIN TO DIMINISH ACROSS THE ATLANTIC WATERS
REDUCING THE RIP CURRENT THREAT SLIGHTLY INTO SUNDAY. WITH LIGHTER
WINDS OVERNIGHT AND CONTINUED LOW LEVEL MOISTURE...PLACED PATCHY
FOG ACROSS INTERIOR AREAS THROUGH THE OVERNIGHT AND EARLY MORNING
HOURS.
SUNDAY INTO MONDAY LOOK MAINLY DRY AS UPPER RIDGING DOMINATES THE
SOUTH FLORIDA PENINSULA. SURFACE WINDS WILL BECOME MORE
SOUTHEASTERLY AS A COLD FRONT APPROACHES FROM THE NORTH. BY MONDAY
NIGHT RIDGING WILL BEGIN TO BREAK DOWN AS THE FRONT PUSHES INTO
CENTRAL FLORIDA. SHOWERS AND POSSIBLE THUNDERSTORMS ARE EXPECTED
TO DEVELOP AND PUSH ACROSS SOUTH FLORIDA AS THE FRONT PASSES
THROUGH TUESDAY AFTERNOON. MODELS SEEM TO HAVE A GOOD HANDLE ON
THE TIMING OF THIS SYSTEM.
BY WEDNESDAY RIDGING RETURNS IN THE WAKE OF THE FRONT. WEDNESDAY
MORNING COULD SEE LOWS IN THE 40S ACROSS INTERIOR AREAS WITH MID
TO UPPER 50S ELSEWHERE. THE OVERALL PATTERN FOR THE LATTER HALF OF
NEXT WEEK SEEMS TO BE MUCH MORE PROGRESSIVE. SOUTHERLY FLOW
QUICKLY RETURNS OVERNIGHT WEDNESDAY INTO THURSDAY AS ANOTHER FRONT
APPROACHES THE NORTHERN GULF OF MEXICO. RAIN CHANCES RETURN FRIDAY
AS THE FRONT PUSHES INTO SOUTH FLORIDA.
&&
.MARINE...
EAST-NORTHEASTERLY WINDS ARE SLOWLY BECOMING MORE EASTERLY AND ARE
BEGINNING TO WEAKEN SLIGHTLY ACROSS THE ATLANTIC WATERS. SHOULD
STILL SEE SEAS IN THE 5 TO 6 FOOT RANGE ACROSS MAINLY THE NEAR AND
OFFSHORE WATERS OF PALM BEACH COUNTY. DECIDED TO KEEP MENTION OF
SMALL CRAFT SHOULD EXERCISE CAUTION FOR THIS AREA. ALSO EXTENDED THE
HIGH RISK OF RIP CURRENTS ACROSS THE BEACHES OF PALM BEACH COUNTY.
&&
.FIRE WEATHER...
STILL NO FIRE WEATHER CONCERNS AT THIS TIME. LOW LEVEL MOISTURE
WILL REMAIN WELL ABOVE CRITICAL THRESHOLDS ACROSS THE ENTIRE AREA
THROUGH THE PERIOD.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 67 80 68 80 / 10 10 - 10
FORT LAUDERDALE 69 80 71 81 / 10 10 - 10
MIAMI 68 81 71 81 / 10 10 - 10
NAPLES 63 81 66 80 / 10 10 - 10
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...HIGH RIP CURRENT RISK UNTIL 7 PM EST THIS EVENING FOR COASTAL
PALM BEACH.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...10/CD
AVIATION/RADAR...85/AG
AREA FORECAST DISCUSSION
NWS JACKSONVILLE FL
245 PM EST SAT DEC 15 2012
.CURRENTLY...REMNANTS OF A SFC TROUGH ARE LOCATED OVER THE OFFSHORE
WATERS WHERE ISOLD TO SCT SHOWERS ARE LOCATED. WEAK WEDGE OF HIGH
PRES AND LIGHT BOUNDARY LAYER WINDS ARE RESULTING IN ONLY SLOW
EROSION OF LOW CLOUDS AND PATCHY FOG CLOUDS ALONG THE COASTAL AREAS
FROM MAYPORT NWD. A HEALTHY CU FIELD HAS DEVELOPED OVER SECTION OF
NE FL AND AN ISOLD SHOWER/SPRINKLE OR TWO CANNOT BE RULED OUT. TEMPS
ARE STRUGGLING TO RISE INTO THE LOWER 60S OVER SE GA BUT MID 70S ARE
FOUND OVER INLAND NE FL. LATEST RAP ANALYSIS SHOWS WEAK MID LEVEL
RIDGING HAS DEVELOPED OVER SW GA AND THE CENTRAL FL PANHANDLE.
.SHORT TERM...
TONIGHT...ONLY ISOLD SHOWERS EXPECTED IN THE EARLY EVENING OVER THE
ERN ZONES AND COASTAL WATERS BEFORE THE INVERTED TROUGH IN THE
MARINE ZONES LIFTS OUT TO THE NE. SMALL DEWPOINT DEPRESSIONS DUE TO
LINGER LOW CLOUDS NEAR THE COAST WILL LIKELY LEAD TO CONTINUED
CHANCES OF FOG THRU MIDNIGHT AND THEN SPREAD INLAND THROUGH THE
NIGHT WITH AREAS OF FOG DEPICTED IN GRIDS. LOCALLY DENSE FOG CAN BE
EXPECTED AT TIMES. LOWS WILL BE WARMER THAN LAST NIGHT DUE TO
DEVELOPING SLY FLOW AND INCREASED MID-UPPER LEVEL CLOUDS.
SUNDAY...FOG AND ANY LOW CLOUDS WILL GRADUALLY DISSIPATE AS SLY FLOW
HELPS MIX OUT SATURATED LOW LEVELS. HIGHS WILL REACH MID TO UPPER
70S. A WEAK COLD FRONT WILL REMAIN LOCATED W OF THE AREA BUT DEEP
LAYER MOISTURE WILL BE WORKING ENE THROUGH THE LOWER MS VALLEY AND
TN VALLEY INTO MOST OF GA DURING THE DAY. WILL KEEP RELATIVELY
MINIMAL POPS AROUND 20 TO NEAR 30% OVER SE GA ZONES...ASSOCD WITH
SHORTWAVE ENERGY PUSHING INTO AL AND GA IN THE AFTN. INSTABILITY LOOKS
TOO WEAK FOR ANY TSTMS.
SUNDAY NIGHT INTO MONDAY...DEEP LAYER TROUGH WILL SHIFT EWD FROM THE
CENTRAL U.S. WITH DEEP LAYER MOISTURE INCREASING FROM THE NW. UPPER
LEVEL DIVERGENCE INCREASES ESPECIALLY ON MON AS UPPER TROUGH
APPROACHES. POPS IN THE CHANCE CATEGORY OVER SE GA AND SLIGHT OVER
EXTREME NE FL SUNDAY NIGHT THEN INCREASING ON MONDAY ALL AREAS.
HIGHEST CHANCES RESERVED FOR INLAND SE GA AT 50-60% AT THIS TIME. A
LOW CAPE BUT HIGH DEEP LAYER SHEAR ENVIRONMENT MAY EXIST ON MON
ENOUGH FOR ISOLD STRONG STORMS WITH GUSTY WINDS BUT APPEARS LIMITED
TO OUR SE GA ZONES ATTM. LOWS IN THE 50S TO NEAR 60 AND HIGHS MON
WILL PUSH TO 75-80 DEG. BY MONDAY EVENING...DEEP LAYER HUMIDITIES
AROUND 70% AND DYNAMIC FORCING WILL BRING AT LEAST CHANCE POPS TO
ALL ZONES AND THE FRONTAL BOUNDARY WILL PUSH THROUGH MOST OF THE
COUNTIES BY EARLY TUE MORNING. TUE-TUE NIGHT...SFC HIGH PRES WILL
MOVE INTO THE REGION FROM THE CENTRAL GULF COAST PRODUCING MOSTLY
CLEAR AND MUCH MORE SEASONABLE TEMPS...WITH HIGHS IN THE 60S AND
LOWS WED MORNING IN THE UPPER 30S IN A FEW SPOTS TO LOWER TO MID 40S.
.LONG TERM...WED-SAT.
THERE IS GOOD MODEL CONSENSUS OF SFC HIGH PRES LOCATED OVER NRN FL
AND SRN GA ON WED WHICH QUICKLY MOVES E INTO THE WRN ATLC AHEAD OF
NEXT PROGRESSIVE TROUGH. THE ASSOCD STRONG SFC COLD FRONT IS PROGGED
TO BE JUST WEST OF THE REGION ON THU...WITH A FRONTAL PASSAGE EITHER
THU NIGHT OR FRI MORNING. HIGH TEMPS ON WED AND THU WILL BE ABOVE
CLIMO DUE TO MOSTLY CLEAR TO PARTLY CLOUDY SKIES AND LOWS WILL TREND
UPWARDS TO ABOVE CLIMO BY THU MORNING AHEAD OF FRONTAL SYSTEM. POPS
IN THE CHANCE CATEGORY BY LATE THU AND DECREASE ON FRI AS THE FRONT
PUSHES SWD DEEP INTO FL. MODERATE TO STRONG COLD ADVECTION IS
INDICATED IN LATEST GUIDANCE BEHIND THE COLD FRONT...GIVEN
MODERATELY STRONG HIGH PRES IN TX-LA. THAT WOULD HELP TREND TEMPS TO
BELOW CLIMO VALUES FRI AND SAT...WITH A CHANCE OF FREEZING TEMPS SAT
MORNING ESPECIALLY INLAND AREAS.
&&
.AVIATION...LOW CLOUDS ALONG THE COAST...AT SSI AND CRG...WILL
CONTINUE TO GRADUALLY LIFT LATE THIS AFTERNOON INTO EARLY EVE.
HOWEVER...WITH DEVELOPING FOG BANK ALONG THE COAST...IT APPEARS CIGS
WILL REMAIN MVFR. ELSEWHERE PREVAILING VFR INTO THE EARLY EVE WITH
CONDITIONS DETERIORATING AFT 06Z AS LOW CLOUDS AND FOG SETS IN. HAVE
PREVAILING LIFR AT ALL TERMINALS AFT 08Z. CONDITIONS SLOWLY IMPROVE
TO VFR BY AROUND 15Z SUN.
&&
.MARINE...LARGE NE SWELLS HAVE BEEN SLOWLY SUBSIDING AND WILL
LET THE ADVISORY EXPIRE AT 20Z AND KEEP AN EXERCISE CAUTION
GOING. LOW CLOUDS AND PATCHY DENSE FOG EXPECTED TONIGHT ALONG
THE COAST AND NEAR SHORE WATERS. WINDS WILL VEER AND SLOWLY
INCREASE AGAIN SUNDAY/MONDAY IN ADVANCE OF A COLD FRONT.
SCA CONDITIONS LOOK LIKELY OFFSHORE IN THE WAKE OF THE FRONT
MONDAY NIGHT INTO TUESDAY NIGHT...WITH CONDITIONS IMPROVING
FOR WEDNESDAY.
RIP CURRENTS: MODERATE RISK TODAY DUE TO E SWELLS PRODUCING SURF
NEAR 2-3 FT.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 52 73 57 76 / 10 20 30 60
SSI 55 71 58 72 / 10 20 20 50
JAX 54 77 58 80 / 10 10 20 40
SGJ 57 75 61 78 / 10 10 10 30
GNV 55 77 55 79 / 10 10 10 30
OCF 55 78 56 80 / 10 10 10 30
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GA...NONE.
AM...SMALL CRAFT ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR ALTAMAHA
SOUND GA TO FERNANDINA BEACH FL 20 NM TO 60 NM OFFSHORE-
FERNANDINA BEACH TO ST AUGUSTINE FL 20 NM TO 60 NM OFFSHORE-
ST AUGUSTINE TO FLAGLER BEACH FL 20 NM TO 60 NM OFFSHORE.
&&
$$
SHASHY/PETERSON/WALKER
AREA FORECAST DISCUSSION
NWS JACKSON KY
131 PM EST SAT DEC 15 2012
.UPDATE...
ISSUED AT 131 PM EST SAT DEC 15 2012
BREAKS IN CLOUDS ARE LEADING TO SLIGHTLY WARMER TEMPS THIS
AFTERNOON...PARTICULARLY IN THE SOUTH AND EAST. HOWEVER...CLOUDS
WILL BE ON THE INCREASE THROUGH THE REMAINDER OF THE AFTERNOON SO
ONLY NUDGED TEMPS UP JUST A COUPLE DEGREES IN THOSE AREAS. OTHERWISE
NO MAJOR CHANGES FOR THE EARLY AFTERNOON UPDATE.
UPDATE ISSUED AT 953 AM EST SAT DEC 15 2012
ISENTROPIC LIFT AS A RESULT OF STRENGTHENING 925 TO 850 FLOW IS
RESPONSIBLE FOR SCATTERED SHOWERS ENTERING THE AREA THIS MORNING.
SFC OBS INDICATE THAT MEASURABLE RAIN IS PROBABLY NOT BE REACHING THE
GROUND IN MANY LOCATIONS...BUT EXPECT AT LEAST SOME LIGHT RAINFALL IS
REACHING THE GROUND UNDER 40 DBZ PLUS ECHOS. WHILE STRONGEST ECHOS
SUGGEST ISOLD TO AT TIMES SCATTERED ACTIVITY...FELT SCATTERED
COVERAGE WOULD BETTER SUFFICE AS AN OVERALL EFFECTIVE POP. TEMPS AND
DEW POINTS ARE PRETTY MUCH ON TARGET...SO ONLY SOME MINOR TWEAKS TO
OTHER GRIDS TO ACCOUNT FOR HOURLY TRENDS. DO SEE SOME BREAKS IN CLOUD
COVER...SO DECREASED SKY COVER JUST SLIGHTLY.
UPDATE ISSUED AT 625 AM EST SAT DEC 15 2012
LATEST RUC AND 06Z NAM SHOW MOISTURE VERY LIMITED TODAY AS THE
BOUNDARY SPREADS INTO THE AREA. GIVEN THIS TREND...HAVE OPTED TO
DECREASE POPS THIS AFTERNOON AND EVENING. LOOKS LIKE WE SHOULD SEE
ISOLATED SHOWERS AT BEST. OTHERWISE...REST OF FORECAST IS ON TRACK.
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 255 AM EST SAT DEC 15 2012
A STRONG MID LEVEL WAVE WILL PUSH NORTHEAST INTO THE WESTERN GREAT
LAKES TODAY. AT THE SURFACE...THIS WILL SEND A SURFACE LOW TOWARDS
CHICAGO WITH A TRAILING WARM FRONT PUSHING ITS WAY EASTWARD ACROSS
KENTUCKY. THE WARM CONVEYOR BELT WILL CONTINUE TO BRING WIDESPREAD
CLOUD COVER TO THE AREA TODAY. THIS CLOUD COVER WILL KEEP OUR HIGHS
IN CHECK...BUT THEY WILL STILL BE MILD WITH READINGS INTO THE LOWER
60S. AS THE FRONT SPREADS EASTWARD THIS AFTERNOON...SCATTERED
SHOWERS WILL PUSH INTO THE I-75 CORRIDOR AND ACROSS EASTERN KENTUCKY
DURING THE EVENING HOURS. STILL SOME QUESTION AS TO HOW MUCH COVERAGE
WILL BE SEEN WITH THE SHOWER ACTIVITY...BUT ECMWF HAS REALLY BACKED
DOWN TONIGHT...WHILE THE NAM REMAINS A BIT MORE AGGRESSIVE. OPTING TO
GO WITH LOW END POPS FOR NOW...BUT POPS COULD CERTAINLY GO HIGHER IF
COVERAGE ENDS UP BETTER AS THE NAM WOULD SUPPORT.
THIS WARM FRONT WILL STALL ACROSS SOUTHEAST KENTUCKY LATE TONIGHT. A
WEAK WAVE WILL PUSH NORTHEAST ACROSS THE TENNESSEE VALLEY LATE
TONIGHT INTO SUNDAY MORNING AND THIS MAY BRING A BETTER SHOT OF
PRECIPITATION INTO SOUTHEAST KENTUCKY. AGAIN...SOME UNCERTAINTY WITH
REGARD TO HOW FAR NORTH THE PRECIPITATION MAY REACH. GOING TO KEEP
THE HIGHEST POPS IN THE SOUTHEAST AND SLOWLY TRAIL THEM OFF TO THE
NORTH. THE BLUEGRASS COULD STAY DRY THROUGH TONIGHT AND TOMORROW IF
YOU BELIEVE THE ECMWF. LOWS TONIGHT WILL REMAIN IN THE 40S AND 50S
WITH GOOD CLOUD COVER ALONG WITH BEING LOCATED IN THE WARM SECTOR.
HIGHS SUNDAY WILL AGAIN WARM INTO THE 60S...BUT THE DEGREE OF
PRECIPITATION COULD TEMPORARILY KEEP THEM LOWER.
HOWEVER...PRECIPITATION SHOULD MOVE OUT BY MID AFTERNOON. NOT SURE IF
WE CAN SQUEEZE OUT ANY SUNSHINE...BUT IT MAY BE POSSIBLE.
.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 410 AM EST SAT DEC 15 2012
THE MODELS ARE ONLY IN FAIR AGREEMENT ALOFT THROUGH THE FIRST PART OF
THE EXTENDED AS THEY START WITH A BROAD TROUGH OVER THE CENTRAL
PLAINS AND VARIOUS SHORT WAVES CROSSING THE BREADTH OF THE NATION.
THIS TROUGH GRADUALLY EVOLVES INTO A SHARPER VERSION OF ITSELF AND
SWINGS THROUGH THE OHIO VALLEY ON MONDAY. AS IT DOES SO...THE LATEST
ECMWF KEEPS ITS CORE OF ENERGY FURTHER NORTH THAN THE GFS WHILE ALSO
PASSING THROUGH A BIT SLOWER. IRONICALLY...AFTER THIS...OUT OF SYNC
MODEL-WISE...SYSTEM LIFTS OUT OF THE AREA THE MEDIUM RANGE PROGS COME
INTO BETTER AGREEMENT ON THE RIDGING THAT FOLLOWS FOR MID WEEK AND
FOR THE MID SECTION OF THE COUNTRY. THIS RIDGE WILL MOVE THROUGH
FAIRLY QUICK ON WEDNESDAY AND WEDNESDAY NIGHT...THOUGH...AND
ATTENTION WILL...IN SHORT ORDER...TURN TOWARD A BREWING TROUGH
THAT WILL BE PLOWING THROUGH THE SOUTHERN PLAINS. HERE...THE ECMWF IS
THE STRONGEST SOLUTION...BUT THE TIMING AND AMPLITUDE ARE SIMILAR TO
THE GFS AND GEM...GIVING THE WHOLE IDEA ENHANCED CREDENCE. THIS
DEEPENING LOW CLOSES OFF AND ROLLS ACROSS THE MISSISSIPPI RIVER ON
THURSDAY AND INTO THE OHIO VALLEY. WITH THIS...THE MODELS ARE
ACTUALLY IN PRETTY GOOD AGREEMENT FOR A FORECAST 144 HOURS OUT. THE
DEEP CLOSED LOW THEN WOULD PLOD ACROSS THE OHIO VALLEY ON FRIDAY WITH
THE ECMWF LESS PROGRESSIVE THAN THE GFS. HAVE FAVORED A BLEND OF
MODEL SOLUTIONS THROUGH THE FIRST PART OF THE EXTENDED...IN LINE
WITH THE CR MODEL LOAD...BUT PREFER THE MORE AMPLIFIED VERSION OF THE
ECMWF FOR THE LATTER PERIODS OF THE FORECAST GIVEN THE APPARENT
MAGNITUDE OF THE UPCOMING PATTERN CHANGE.
SENSIBLE WEATHER WILL FEATURE A CHANCE OF SHOWERS CONTINUING THROUGH
THE SOUTHERN PORTION OF THE CWA ON SUNDAY NIGHT...STRETCHING
NORTHWEST WITH TIME AS A FINAL SFC WAVE PASSES THROUGH THE AREA ON
MONDAY BEFORE CLEARING AND TAKING THE BULK OF THE PCPN CHANCES WITH
IT ON MONDAY NIGHT. A FEW SHOWERS MAY LINGER IN THE FAR EAST EARLY ON
TUESDAY...BUT...FOR THE MOST PART...HIGH PRESSURE WILL BUILD INTO
THE AREA AND PROVIDE WHAT APPEARS TO BE ONE LAST WARM SHOT FOR THE
MONTH AROUND MIDWEEK...AHEAD OF A POTENT SYSTEM DUE IN HERE TO END
THE WORK WEEK. THIS FINAL SYSTEM...OF THE EXTENDED AND BEYOND...WILL
BE DEEPENING AS IT MOVES THROUGH AND WILL BRING A GOOD SLUG OF
MOISTURE AHEAD OF ITS COLD FRONT FOLLOWED BY PLENTY OF COLD AIR IN
ITS WAKE. THE SLOW AND STRENGTHENING NATURE OF THE LOW WILL PROBABLY
KEEP ITS WRAP AROUND PCPN IN THE AREA THROUGH FRIDAY...WITH MUCH OF
THIS FALLING AS LIGHT SNOW SHOWERS AND PRESENTING A POTENTIAL FOR AN
EXTENDED PERIOD WINTRY WEATHER INTO THE WEEKEND...DEFINITELY MORE THAN
WE HAVE SEEN THUS FAR THIS SEASON.
THE CR GRID BLEND CAME IN REASONABLE...BUT DID NUDGE IT MORE TOWARD
THE ECMWF IN THE LATTER PERIODS...PARTICULARLY WITH RESPECT TO POPS.
ALSO...MADE SOME MINOR TERRAIN BASED ADJUSTMENTS TO LOW TEMPERATURES
FOR TUESDAY AND WEDNESDAY NIGHT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 131 PM EST SAT DEC 15 2012
VFR CONDITIONS EXPECTED THROUGH ROUGHLY THE FIRST 18 HOURS OF THE
FORECAST WINDOW. THEREAFTER RAIN SHOWERS WILL OVERSPREAD THE AREA
DROPPING CONDITIONS INTO MVFR TERRITORY. WINDS WILL GENERALLY RUN
SOUTHERLY AT 5 TO 10 KTS. MAINTAINED LLWS THROUGH THE OVERNIGHT
PERIOD TO ACCOUNT FOR INCREASING SOUTHWEST WINDS ALOFT...TO AROUND
40 KTS AS COMPARED TO LIGHT SOUTHERLY WINDS AT THE SFC.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
UPDATE...RAY
SHORT TERM...KAS
LONG TERM....GREIF
AVIATION...RAY
AREA FORECAST DISCUSSION...UPDATED
NWS PITTSBURGH PA
439 PM EST SAT DEC 15 2012
.SYNOPSIS...
A WEAK UPPER LEVEL WAVE WILL BRING THE CHANCE FOR SHOWERS THIS
EVENING...WITH ANOTHER WAVE BRINGING A CHANCE ON SUNDAY. A LOW
PRESSURE SYSTEM...WILL PROVIDE US WITH SHOWERS MONDAY INTO
TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
HAVE LOWERED POPS TONIGHT. LOWER ATMOSPHERE IS VERY DRY WITH T/TD
DEPRESSIONS IN THE 20 DEGREE RANGE. THE BAND OF SHOWERS MOVING
THROUGH IS HAVE A VERY DIFFICULT TIME REACHING THE GROUND...WITH
MOST LOCATIONS REPORTING JUST SPRINKLES. THE WEAK UPPER LEVEL
WAVE...THAT IS CAUSING THE ELEVATED PRECIPITATION...WILL MOVE TO
THE EAST LATER THIS EVENING. A LARGE DRY SLOT ALOFT WILL SPREAD
ACROSS THE UPPER OHIO VALLEY BEHIND THE EXITING WAVE. THIS WILL
REMOVE THE RISK FOR SHOWERS LATER TONIGHT.
TWEAKED TEMPERATURES BASED ON RECENT HRRR AND GFS LAMP MODEL
OUTPUT...WHICH SHOW LOWS TONIGHT CAN BE 15 TO 20 DEGREES WARMER
THAN NORMAL AND ALL ABOVE FREEZING.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
EXPECT MILD CONDITIONS ALTHOUGH THERE CONTINUES TO BE UNCERTAINTY
REGARDING THE CHANCES OF SHOWERS SUNDAY INTO EARLY MONDAY.
NAM AND GFS MODEL PROFILES SHOW SOME SHALLOW INSTABILITY BUT LIFT
APPEARS LACKING AS THE INITIAL LOW CENTER WILL BE MOVING EASTWARD
THROUGH SOUTHERN CANADA AND A SECOND LOW CENTER WILL LIKELY NOT
DEVELOP UNTIL SUNDAY NIGHT NEAR ARKANSAS. FOR NOW HAVE MAINTAINED
A LOW CHANCE OF SHOWERS FOR SUNDAY AND SUNDAY NIGHT.
WITH SREF AND NAM MODEL OUTPUT CONTINUING TO SHOW A ROBUST LOW
PRESSURE SYSTEM MOVING NORTHEASTWARD FROM ARKANSAS MONDAY TO NEW
YORK STATE EARLY TUESDAY...SHOWERS WILL BECOME LIKELY LATE MONDAY
INTO DAYTIME TUESDAY.
BLEND OF GFS AND NAM MOS AND SREF SHOW TEMPERATURES WILL REMAIN
PARTICULARLY MILD...NEARLY 15 TO 20 DEGREES WARMER THAN
NORMAL...UNTIL THE LOW PRESSURE CENTER EXITS NORTHEAST PAST NEW
YORK STATE EARLY TUESDAY. THEN WESTERLY WINDS WILL PROVIDE A POST
SYSTEM COOL DOWN...ALTHOUGH CONSENSUS OF MODEL OUTPUT SHOW TEMPERATURES
NOT GOING COLDER THAN FREEZING UNTIL TUESDAY NIGHT. SO HAVE
FORECASTED NO MORE THAN A MIX WITH SNOW SHOWERS LATE TUESDAY
AFTERNOON.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LOW PRESSURE WILL MOVE OFF TO THE EAST TUESDAY NIGHT...WITH
PRECIPITATION DIMINISHING FROM SOUTHWEST TO NORTHEAST. WHILE FLOW
WILL BE FAVORABLE FOR LAKE EFFECT SNOW WEDNESDAY...INVERSION LEVELS
CURRENTLY FORECAST TO TOP OUT BELOW 5 KFT WOULD LIKELY LIMIT SNOW TO
LITTLE MORE THAN FLURRIES.
MEANWHILE...NEXT STORM SYSTEM WILL DEVELOP IN THE PLAINS AND
BEGIN TO AFFECT THE REGION THURSDAY. WITH GOOD AGREEMENT FROM 12Z
GFS/ECMWF AND 00Z NAEFS...HAVE BUMPED UP POPS TO LIKELY THURSDAY
AFTERNOON AND EVENING AS BULK OF PRECIPITATION WILL COME THROUGH
WITH COLD FRONT.
LOW CENTER WILL THEN MEANDER ACROSS THE EASTERN GREAT LAKES ON
FRIDAY. THE LOW WILL PUMP COLD AIR INTO THE AREA ON FRIDAY...AND
TEMPERATURES MAY DECREASE THROUGHOUT THE ENTIRE DAY. COLD AIR AND
ADDITIONAL MOISTURE WILL ALLOW FOR A MUCH BETTER CHANCE OF LAKE
EFFECT/UPSLOPE SNOW SHOWERS FRIDAY AND SATURDAY COMPARED TO THE
MID WEEK STORM.
ABOVE NORMAL TEMPERATURES WEDNESDAY AND THURSDAY WILL TUMBLE
BELOW NORMAL FOR FRIDAY AND SATURDAY BEHIND THE COLD FRONT.
&&
.AVIATION /22Z SATURDAY THROUGH THURSDAY/...
LINE OF SHOWERS IS EXPECTED TO CROSS MOST TERMINALS THROUGH THE NEXT
12 HOURS. DRY AIR AT LOW LEVELS MAY ACTUALLY PREVENT RAIN FROM
REACHING THE GROUND. NEARLY ALL UPSTREAM LOCATIONS RECEIVING RAIN
HAVE REMAIN VFR WITH ONSET OF PRECIPITATION...AND EXPECT THE SAME
LOCALLY. SOME MODELS INDICATE THAT SHOWERS MAY SCATTER IN COVERAGE
OVER EASTERN OHIO AND WESTERN PENNSYLVANIA.
HAVE KEPT MGW DRY AT THIS POINT. CIGS WILL LOWER FROM MID DECK TO
LOW VFR WITH ARRIVAL OF RAIN...AND SHOULD STAY THIS WAY THROUGH
THE REST OF THE TAF PERIOD. THE EXCEPTIONS ARE FKL AND DUJ...WHICH
ARE EXPECTED TO DROP TO MVFR CIGS BEFORE SUNRISE.
EAST WINDS AT 5-10 KTS WILL SLOWLY VEER TO THE SOUTH THROUGH
SUNDAY MORNING.
.OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/...
THERE WILL BE A CHANCE OF SHOWERS SUNDAY NIGHT INTO MONDAY...WITH
MORE WIDESPREAD RAIN/SNOW SHOWERS AND RESTRICTIONS MONDAY NIGHT AND
TUESDAY. RESTRICTIONS MAY REMAIN TUESDAY NIGHT INTO WEDNESDAY NIGHT
WITH SOME PARTIAL CLEARING. ANOTHER LOW PRESSURE SYSTEM WILL BRING
RAIN/SNOW SHOWERS ONCE AGAIN ON THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
336 PM EST SAT DEC 15 2012
.SYNOPSIS...
LOW PRESSURE...FROM IOWA...MOVING NORTHEAST TO MICHIGAN...WILL
PUSH SHOWERS EASTWARD THROUGH THE UPPER OHIO VALLEY TONIGHT WITH A
FEW STRAGGLERS LEFT FOR SUNDAY. A SECOND LOW PRESSURE
SYSTEM...WILL DEVELOP NEAR ARKANSAS SUNDAY NIGHT...AND ALSO MOVE
NORTHEASTWARD TO PROVIDE US WITH SHOWERS MONDAY INTO TUESDAY.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
BLEND OF RAP AND WRF-NMM MODEL OUTPUT CONTINUE TO SHOW A BAND OF
SHOWERS WILL MOVE EASTWARD THROUGH THE UPPER OHIO VALLEY EARLY
TONIGHT. THESE SHOWERS WILL BE ASSOCIATED WITH A LOW PRESSURE
CENTER MOVING NORTHEASTWARD FROM IOWA TO MICHIGAN...THAT WILL DEVELOP
A LOWLEVEL JET ACROSS THE UPPER OHIO VALLEY TONIGHT. THE RESULTING
NORTHEAST SURGE OF JET-RELATED LIFT AND MOISTURE IS WHAT WILL PUSH
A BAND OF SHOWERS EASTWARD THROUGH THE UPPER OHIO VALLEY EARLY
TONIGHT.
HAVE LEFT A CHANCE OF SHOWERS LATE TONIGHT AS THE MODELS SHOW
THERE CAN BE STRAGGLERS.
TWEAKED TEMPERATURES BASED ON RECENT HRRR AND GFS LAMP MODEL
OUTPUT...WHICH SHOW LOWS TONIGHT CAN BE 15 TO 20 DEGREES WARMER
THAN NORMAL AND ALL ABOVE FREEZING.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
EXPECT MILD CONDITIONS ALTHOUGH THERE CONTINUES TO BE UNCERTAINTY
REGARDING THE CHANCES OF SHOWERS SUNDAY INTO EARLY MONDAY.
NAM AND GFS MODEL PROFILES SHOW SOME SHALLOW INSTABILITY BUT LIFT
APPEARS LACKING AS THE INITIAL LOW CENTER WILL BE MOVING EASTWARD
THROUGH SOUTHERN CANADA AND A SECOND LOW CENTER WILL LIKELY NOT
DEVELOP UNTIL SUNDAY NIGHT NEAR ARKANSAS. FOR NOW HAVE MAINTAINED
A LOW CHANCE OF SHOWERS FOR SUNDAY AND SUNDAY NIGHT.
WITH SREF AND NAM MODEL OUTPUT CONTINUING TO SHOW A ROBUST LOW
PRESSURE SYSTEM MOVING NORTHEASTWARD FROM ARKANSAS MONDAY TO NEW
YORK STATE EARLY TUESDAY...SHOWERS WILL BECOME LIKELY LATE MONDAY
INTO DAYTIME TUESDAY.
BLEND OF GFS AND NAM MOS AND SREF SHOW TEMPERATURES WILL REMAIN
PARTICULARLY MILD...NEARLY 15 TO 20 DEGREES WARMER THAN
NORMAL...UNTIL THE LOW PRESSURE CENTER EXITS NORTHEAST PAST NEW
YORK STATE EARLY TUESDAY. THEN WESTERLY WINDS WILL PROVIDE A POST
SYSTEM COOL DOWN...ALTHOUGH CONSENSUS OF MODEL OUTPUT SHOW TEMPERATURES
NOT GOING COLDER THAN FREEZING UNTIL TUESDAY NIGHT. SO HAVE
FORECASTED NO MORE THAN A MIX WITH SNOW SHOWERS LATE TUESDAY
AFTERNOON.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
LOW PRESSURE WILL MOVE OFF TO THE EAST TUESDAY NIGHT...WITH
PRECIPITATION DIMINISHING FROM SOUTHWEST TO NORTHEAST. WHILE FLOW
WILL BE FAVORABLE FOR LAKE EFFECT SNOW WEDNESDAY...INVERSION LEVELS
CURRENTLY FORECAST TO TOP OUT BELOW 5 KFT WOULD LIKELY LIMIT SNOW TO
LITTLE MORE THAN FLURRIES.
MEANWHILE...NEXT STORM SYSTEM WILL DEVELOP IN THE PLAINS AND
BEGIN TO AFFECT THE REGION THURSDAY. WITH GOOD AGREEMENT FROM 12Z
GFS/ECMWF AND 00Z NAEFS...HAVE BUMPED UP POPS TO LIKELY THURSDAY
AFTERNOON AND EVENING AS BULK OF PRECIPITATION WILL COME THROUGH
WITH COLD FRONT.
LOW CENTER WILL THEN MEANDER ACROSS THE EASTERN GREAT LAKES ON
FRIDAY. THE LOW WILL PUMP COLD AIR INTO THE AREA ON FRIDAY...AND
TEMPERATURES MAY DECREASE THROUGHOUT THE ENTIRE DAY. COLD AIR AND
ADDITIONAL MOISTURE WILL ALLOW FOR A MUCH BETTER CHANCE OF LAKE
EFFECT/UPSLOPE SNOW SHOWERS FRIDAY AND SATURDAY COMPARED TO THE
MID WEEK STORM.
ABOVE NORMAL TEMPERATURES WEDNESDAY AND THURSDAY WILL TUMBLE
BELOW NORMAL FOR FRIDAY AND SATURDAY BEHIND THE COLD FRONT.
&&
.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
LINE OF SHOWERS IS EXPECTED TO CROSS MOST TERMINALS THROUGH THE NEXT
12 HOURS. DRY AIR AT LOW LEVELS MAY ACTUALLY PREVENT RAIN FROM
REACHING THE GROUND. NEARLY ALL UPSTREAM LOCATIONS RECEIVING RAIN
HAVE REMAIN VFR WITH ONSET OF PRECIPITATION...AND EXPECT THE SAME
LOCALLY. SOME MODELS INDICATE THAT SHOWERS MAY SCATTER IN COVERAGE
OVER EASTERN OHIO AND WESTERN PENNSYLVANIA.
HAVE KEPT MGW DRY AT THIS POINT. CIGS WILL LOWER FROM MID DECK TO
LOW VFR WITH ARRIVAL OF RAIN...AND SHOULD STAY THIS WAY THROUGH
THE REST OF THE TAF PERIOD. THE EXCEPTIONS ARE FKL AND DUJ...WHICH
ARE EXPECTED TO DROP TO MVFR CIGS BEFORE SUNRISE.
EAST WINDS AT 5-10 KTS WILL SLOWLY VEER TO THE SOUTH THROUGH
SUNDAY MORNING.
.OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/...
THERE WILL BE A CHANCE OF SHOWERS SUNDAY NIGHT INTO MONDAY...WITH
MORE WIDESPREAD RAIN/SNOW SHOWERS AND RESTRICTIONS MONDAY NIGHT AND
TUESDAY. RESTRICTIONS MAY REMAIN TUESDAY NIGHT INTO WEDNESDAY NIGHT
WITH SOME PARTIAL CLEARING. ANOTHER LOW PRESSURE SYSTEM WILL BRING
RAIN/SNOW SHOWERS ONCE AGAIN ON THURSDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1210 PM EST SAT DEC 15 2012
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 442 AM EST SAT DEC 15 2012
00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A SPLIT FLOW ACRS
NAMERICA WITH ZONAL NRN BRANCH OVER CANADA KEEPING THE REAL COLD
ARCTIC AIR LOCKED TO THE N OF THE BORDER. IN FACT...A LOOK AT THE
00Z H85 RAOBS SHOW TEMPS AT THAT LVL ABV 0C OVER ALL OF THE CONUS
EXCEPT THE NE AND PAC NW. EARLY THIS MRNG...THE UPR GRT LKS ARE
UNDER THE INFLUENCE OF A FAIRLY SHARP NRN BRANCH UPR RDG OVER
ONTARIO...AND LOCAL 00Z RAOBS SHOW A SHAPR SUBSIDENCE INVRN BASE
ARND H925 UNDER MID LVL DRY AIR. THE NEAR SFC LYR IS RATHER
MOIST...SO THERE IS QUITE A BIT OF LO CLD TRAPPED UNDER THIS INVRN.
TEMPS ARE GENERALLY WELL ABV NORMAL...IN THE 25 TO 30F RANGE. TO THE
SW...STRONG NEGATIVELY TILTED DISTURBANCE EMBEDDED IN THE WSW SRN
BRANCH FLOW IS LIFTING NEWD THRU THE CENTRAL PLAINS SUPPORTED BY
130KT H3 JET MAX OVER TX. ALTHOUGH THE MID LVLS OVER THE UPR LKS ARE
DRY...HI CLD WELL IN ADVANCE OF THIS SHRTWV IS SPILLING INTO THE
AREA. THE CLOSEST PCPN IN THE FORM OF RA AT 06Z HAS MOVED INTO
IA/NRN IL IN THE SURGE OF MSTR AHEAD OF THIS SHRTWV ENHANCED BY 50KT
H85 S LLJ OVER THE SRN PLAINS.
MAIN FCST CONCERNS IN THE SHORT TERM ARE MANY AND REVOLVE ARND
TIMING AND TYPE OF PCPN ASSOCIATED WITH DISTURBANCE MOVING NEWD THRU
THE PLAINS. ALTHOUGH NCEP INDICATES A PREFERENCE FOR THE 00Z GFS
GIVEN PRESENT NEGATIVE TILT OF THE DISTURBANCE/STRONG JET MAX
ROTATING NEWD ON ITS ERN FLANK...FCSTS SHOWING THIS DISTURBANCE
WEAKENING AS IT MOVES TOWARD THE NE WITH JET CORE SHEARING OUT THRU
THE GRT LKS INDICATE THE VERY CONSISTENT...FARTHER S 12Z ECMWF MIGHT
BE ON THE RIGHT TRACK. SO OPTED TO USE THE COMPROMISE 00Z NAM FOR
FCST DETAILS. OVERALL GIVEN ANTECEDENT DRY AIR ALF AND TRACK OF
STRONGER DYNAMICS TO THE SE...THIS PCPN EVENT WL NOT BE SGNFT.
TODAY...THIS MRNG SHOULD BE MAINLY PCPN FREE WITH LINGERING MID LVL
DRY AIR. THE ONLY CONCERN IS THE POTENTIAL FOR SOME -DZ/-FZDZ OVER
MAINLY THE CENTRAL ZNS WITH UPSLOPE ESE FLOW OFF LK MI AND THE
ARRIVAL OF BIT HIER H95-9 SPECIFIC HUMIDITY. DEEPER MSTR IS PROGGED
TO ARRIVE THIS AFTN...BUT MODELS REMAIN CONSISTENT SHOWING SHARPEST
H85-5 QVECTOR CNVGC PASSING TO THE SE AS DISTURBANCE WEAKENS AS IT
MOVES OUT OF THE SRN BRANCH TROF OVER THE DESERT SW. THE IMPRESSIVE
JET CORE IS ALSO FCST TO WEAKEN AND SHEAR OUT A BIT JUST S OF THE
LOWER LKS. IN FACT...MODEL QPF IS RATHER MODEST...WITH A BIT MORE
OVER THE SE CWA CLOSER TO THE SHARPER ISENTROPIC ASCENT/QVECTOR
CNVGC/UPR DVGC. TENDED TO CUT POPS FM PREVIOUS FCST A BIT ESPECIALLY
AWAY FM THE SE CWA TO REFLECT THE CONSENSUS ON THE TRACK OF BETTER
DYNAMIC SUPPORT. GIVEN THE WARMTH OF THE AIRMASS IN PLACE...SUSPECT
ANY PCPN WL AT LEAST START AS RA. BUT DRYNESS OF THE MID LVLS AND
POTENTIAL EVAP COOLING MIGHT CAUSE SOME OF THIS PCPN TO AT LEAST MIX
WITH SN...ESPECIALLY OVER THE HIER TERRAIN OF THE CENTRAL. BUT THE
LACK OF SGNFT DYNAMIC FORCING/OMEGA SUGS THIS PROCESS WL NOT BE AS
VIGOROUS AS MIGHT OTRW BE THE CASE. WITH THE SFC LO WEAKENING AS IT
MOVES TO THE NE...TENDED TOWARD THE LOWER SIDE OF GUIDANCE FOR
TEMPS...WHICH IS IN GOOD AGREEMENT WITH PREVIOUS FCST.
TONIGHT...MAIN DISTURBANCE PASSING TO THE SE IS FCST TO SHIFT AWAY
TO THE E...SO SUSPECT PCPN OVER MUCH OF THE CWA WL DIMINISH TO JUST
A BIT OF -RA/-SN PERHAPS -DZ/-FZDZ AFTER 00Z AS GUIDANCE SHOWS
LARGER SCALE QVECTOR DVGC IN PLACE THIS EVNG. ADDED MENTION OF FOG
IN UPSLOPING AREAS OVER MAINLY THE CENTRAL IN LLVL SE FLOW WITH
LINGERING LLVL MSTR UNDER SOME UPR DRYING. BUT SHRTWV EMBEDDED IN
NRN BRANCH IS PROGGED TO BRING A RETURN OF SOME LARGER SCALE QVECTOR
CNVGC/UPR DVGC LATER OVER THE W...SO TRENDED POPS HIER THERE OVERNGT.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 442 AM EST SAT DEC 15 2012
SUNDAY...THE MODELS ARE VERY SIMILAR WITH THE OVERALL
PATTERN...INDICATING A LINGERING MID/UPPER LEVEL TROUGH OVER THE
NORTHERN GREAT LAKES AND A DOWNSTREAM BLOCKING RIDGE OVER QUEBEC.
THERE ARE MORE SUBTLE DIFFERENCES WITH THE WEAK SHORTWAVES MOVING
THROUGH NRN WI AND UPPER MI THAT MAY ENHANCE ANY PCPN. WITH
RELATIVELY ABUNDANT MOISTURE IN PLACE OVER THE AREA...THE WEAK TO
MODERATE QVECTOR CONV AND POTENTIAL FOR 800-600 MB FGEN (ESPECIALLY
OVER THE WEST PER NAM) THE FORECAST KEEPS LIKELY POPS GOING BUT FOR
LIGHT QPF...LESS THAN A TENTH OF AN INCH. AT THE SFC...A TROUGH WILL
WILL LINGER OVER UPPER MI...RESULTING IN A RELATIVELY WARM LOW LEVEL
TEMP PROFILE. USING A GFS/NAM/ECMWF COMPROMISE ON LOW LEVEL
TEMPS...EXPECT MAINLY SNOW OVER THE WEST BUT A RAIN/SNOW MIX EAST AND
MAINLY RAIN NEAR LAKE MICHIGAN.
SUNDAY NIGHT INTO MONDAY...THE MORE WIDESPREAD PCPN SHOULD DIMINISH
SUNDAY NIGHT AS THE MID LEVEL AND SFC TROUGHS LIFT TO THE NORTHEAST.
COLDER AIR WILL THEN FILTER INTO THE AREA BRINGING 850 MB TEMPS DOWN
TO NEAR -6C. THE COLD AIR COMBINED WITH MOIST CYCLONIC LOW LEVEL
FLOW MAY SUPPORT SOME LIGHT LAKE ENHANCED SNOW OVER THE NORTH. THE
GREATEST POTENTIAL FOR ANY ACCUMULATING SNOW IS LIKELY OVER THE WEST
WHERE THE ONSHORE FLOW WOULD BE A BIT STRONGER COMPARED TO THE EAST
WHERE ONLY LIGHT WINDS PREVAIL UNDER THE INFLUENCE OF LAKE INDUCED
TROUGHING.
TUE-FRI...MODELS WERE SIMILAR WITH TREND TOWARD A PROGRESSIVE
PATTERN WHICH WILL BRING A MID/UPPER LEVEL TROUGH INTO THE WRN CONUS
TUE AND INTO THE PLAINS BY WED NIGHT. MID LEVEL AND SFC RIDGING
AHEAD OF THIS FEATURE WILL RESULT IN DRY WEATHER WITH TEMPS NEAR OR
SLIGHTLY ABOVE SEASONAL AVERAGES. THERE IS THE POTENTIAL FOR A
SIGNIFICANT STORM SYSTEM BY THU INTO FRI MOVING OUT OF THE PLAINS
TOWARD THE GREAT LAKES. THE GFS/ECMWF BRING THE SFC LOW INTO THE SRN
LAKES WITH POTENTIAL FOR SNOW AND LAKE ENHANCED SNOW OVER UPPER MI.
AS WOULD BE EXPECTED FOR A FORECAST FOR DAYS 5/6... THERE IS STILL
CONSIDERABLE UNCERTAINTY WITH THE PATH AND STRENGTH OF THE SYSTEM.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1209 PM EST SAT DEC 15 2012
IFR/LIFR CONDITIONS WL PREDOMINATE THIS FCST PERIOD WITH GRADUAL
INFLUX OF DEEPER MSTR AND THE ARRIVAL OF SOME -RASN THIS AFTN ON THE
N FLANK OF LOW PRESSURE MOVING TOWARD THE GREAT LKS. VLIFR
CONDITIONS WILL OCCUR TONIGHT THROUGH SUNDAY MORNING WITH
DIMINISHING WINDS UNDER DRYING ALOFT.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 442 AM EST SAT DEC 15 2012
AS LO PRES APPROACHES FROM THE SW...TIGHTENING GRADIENT WILL SUPPORT
AN INCREASING SE WIND INTO TONIGHT. AFTER COORDINATION WITH
ENVIRONMENT CANADA...OPTED TO ISSUE A GALE WARNING FOR THE FAR E...
WHERE THE GRADIENT IS EXPECTED TO BE TIGHTEST AND TERRAIN OFTEN
ACCENTUATES A SE FLOW. OVER THE W WHERE THE GRADIENT WILL BE
WEAKER...WIND SHOULD REMAIN UNDER 25 KTS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
GALE WARNING FROM 6 PM THIS EVENING TO 4 AM EST SUNDAY FOR
LSZ267.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...KC
LONG TERM...JLB
AVIATION...07
MARINE...KC
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
330 PM CST SAT DEC 15 2012
.DISCUSSION...
NICE STORM TRACK FOR WHAT MIGHT HAVE BEEN A DECENT SNOWFALL
EVENT...BUT UNUSUALLY WARM SYSTEM MID DECEMBER SYSTEM HAS AT LEAST
LEFT US WITH SOME NEEDED RAIN WITH WIDESPREAD QPF IN THE .25 TO
TO .40 RANGE. PCPN HAS CHGD TO MAINLY SNOW IN THE DEFORMATION ZONE
ACROSS W MN ON LEADING EDGE OF ENHANCED IR IMAGERY WHERE WE HAVE
SEEN A FEW SNOW AMOUNTS OF 2 INCHES OR SO. ATTM THE LEADING EDGE
WHERE PCPN IS MAINLY SNOW LIES FROM ARND BRD TO OVL. CLOUD
TOPS...HOWEVER HAVE BEEN WARMING AS DEFORMATION ZONE SLIDES EAST.
WILL LET THAT PORTION OF THE WINTER WX ADVY WHICH WAS TO EXPIRE
AT 6 PM EXPIRE AS SCHEDULED...WILL ALSO CANCEL ADVY FOR STEVENS
COUNTY IN WC MN AS DEFORMATION ZONE WILL BE EAST OF THAT AREA
SOON. ALSO EXPECT ANY SNOW TO BE AN INCH OR LESS ON EAST SIDE OF
ADVY IN POLK AND CHISAGO COUNTIES...THUS WILL CANCEL THAT PART OF
ADVY AT 6PM. LEFT A SWATH OF COUNTIES IN CNTL MN IN ADVY UNTIL THE
SCHD 06Z EXPIRATION TIME...BUT SNOW AMOUNTS WILL BE
MARGINAL...PERHAPS 1 TO 3 INCHES.
FOG AND LOW STRATUS IN BAGGY SFC PRESSURE GRADIENT IN S MN WILL
CONTINUE INTO THE EVENING...BUT WILL BEGIN TO SEE AN IMPRVG TREND
IN W AREAS BY 00Z AND ACRS AREA BY 04Z AS SURFACE WINDS BECOME NW
AND INCREASE AS LOW LIFTS INTO WI.
A BIT COOLER FOR SUNDAY WITH NW WINDS IN WAKE OF LOW PRESSURE
LIFTING OUT OF WI AND TWRD THE GREAT LAKES. ANY BINOVC IN WC MN
SUNDAY NIGHT WILL ALLOW TEMPS THERE TO TAKE A DIVE AS HIGH
PRESSURE MOVES IN AND THE NEW SNOW ASSISTS RADIATION COOLING.
MODELS HAVE A BIT BETTER CONTINUITY ON WEAK WAVE MOVING THRU ON
TUESDAY. BEST CHANCE OF ANY SMALL ACCUMS SHUD BE IN CNTL MN...WITH
BETTER CHANCES FARTHER NORTH.
STORM TRACK FOR LATE WED/THURS STILL APPEARS TO BE TOO FAR SOUTH
FOR SIGNIFICANT IMPACTS IN OUR AREA WITH GFS/ECMWF BRINGING RAPIDLY
DEEPENING SURFACE LOW OUT OF MO INTO N ILLINOIS IN THE SOUTHERN STREAM.
LEFT SOME LIKELY POPS IN THE FAR SE...BUT MAY NEED TO BE TRENDED
DOWNWARD.
&&
.AVIATION.../18Z TAF ISSUANCE/
BASED ON THE LATEST REGIONAL RADAR/SFC OBS AND THE RAP SHORT TERM
MODEL...DECIDED TO KEEP AXN ALL SNOW THRU THE TAF PERIOD...WITH
RWF/STC SLOWLY CHANGING OVER BY 21-00Z. DEPENDING UPON HOW THE
UPPER SYSTEM BEGINS TO PIVOT ACROSS NW IA...AND THEN NORTHEAST
ACROSS SC/EC MN THIS EVENING WILL DEPEND ON THE CHG OVER AND HOW
MUCH SNOWFALL IS EXPECTED. BEST AREA OF ACCUMULATING SNOWFALL THIS
AFTN WILL BE AXN AS THE MAIN STORM BEGINS TO PIVOT AND THE
PRECIPITATION HOLDS IN WC/CENTRAL MN OVER THE NEXT SEVERAL HRS.
THE DRY SLOT ACROSS SC/SE MN WILL LIKELY AFFECT RNH/MSP/EAU WITH
SEVERAL HRS OF MAINLY -DZ...BUT IFR/LIFR CIGS ARE A GOOD BET. SFC
WINDS WILL REMAIN E/SE ACROSS THE EASTERN FA...THEN MORE NE/N BY
THE LATE AFTN...THEN SHIFTING TO THE W/NW THIS EVENING. AXN/RWF
WILL SEE THE CHG FROM NE/E WINDS TO A MORE N/NW WIND LATER THIS
AFTN...AND CONTINUING OVERNIGHT. BEST TIME PERIOD OF A CHC OF
LIGHT TO MODERATE SNOWFALL AT STC/RNH/MSP WILL BE AFT 00-3Z WITH
SOME 1/2SM SN POSSIBLE ARND 6Z. LATER SHIFTS CAN UPDATE BASED ON
REGIONAL RADAR. EXPECT CONDS TO SLOWLY IMPROVE AFT 09-12Z...BUT
REMAIN IN THE MVFR RANGE.
KMSP...
FIRST BATCH OF -RA/RA WILL DECREASE TO -DZ IN THE NEXT HR OR TWO.
AFT 20-21Z EXPECT A PERIOD OF IFR CIGS AND -DZ. WINDS WILL REMAIN
FROM THE E/SE AND UNDER 10 KTS. WINDS WILL SLOWLY BECOME NE/N THIS
EVENING AS THE SFC LOW MOVES OVERHEAD. BY 3Z EXPECT WINDS TO BE
MORE NW/NNW AND SLIGHTLY INCREASING BY 6Z. CHG OVER TO RASN
MIXTURE WILL OCCUR AFT THE WINDS SHIFT TO THE N/NNW...WITH A
PREDOMINATE PERIOD OF -SN AND 3/4SM VSBYS BETWEEN 3-9Z. AFT
12Z...MOST OF THE ENERGY WITH THIS SYSTEM WILL BE EAST OF
MSP...WITH MVFR CIGS HOLDING THROUGH THE AFTN.
/OUTLOOK FOR KMSP/
SUN AFTN...SLOW IMPROVEMENT. CHC -SN EARLY. NW WIND 5-10 KTS.
MON...VFR CONDS EXPECTED...POSSIBLE MVFR CEILINGS EARLY. NW WIND 5KTS.
TUE...MVFR CIGS WITH -SN POSSIBLE. WINDS AROUND 5 KTS.
WED...VFR. ..JLT..
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR BENTON-
DOUGLAS-ISANTI-KANABEC-MILLE LACS-MORRISON-POPE-SHERBURNE-
STEARNS-TODD.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR CHIPPEWA-
CHISAGO-KANDIYOHI-LAC QUI PARLE-STEVENS-SWIFT-YELLOW
MEDICINE.
WI...WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR POLK.
&&
$$
BAP/JLT
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1145 AM CST SAT DEC 15 2012
.DISCUSSION...
WILL START WITH MAIN CHANGES THAT HAVE COME ABOUT WITH THIS
FORECAST PACKAGE. FIRST...AS OF 3 AM...ALL BUT MADISON AND
APPLETON IN WRN MN HAVE RISEN ABOVE FREEZING...SO THE THREAT FOR
FREEZING RAIN IS NOW LOOKING MINIMAL. SECOND CHANGE...DEFORMATION
PRECIP WEST OF THE LOW TRACK IS LOOKING TO BE MUCH MORE ROBUST
ACROSS WRN MN THIS AFTERNOON AND WORKING ACROSS CENTRAL MN
TONIGHT. BOOSTED SNOW AMOUNTS SOME...WITH 4 INCHES NOW FORECAST UP
IN THE NW CWA...THOUGH DEPENDING ON HOW QUICKLY TRANSITION TO SNOW
OCCURS...THIS COULD END UP BEING MORE. OTHER IMPACT OF THE
DEFORMATION PRECIP IS THAT HEAVIER SNOW IS NOW EXPECTED FROM THIS
AFTERNOON INTO TONIGHT...SO EXTENDED WINTER WEATHER ADVY OUT IN
TIME TO 00Z FOR WEST CENTRAL MN AND 06Z TONIGHT FOR CENTRAL MN
OVER TO POLK COUNTY WI.
INTERESTING WATER VAPOR IMAGERY THIS MORNING WITH TWO BAROCLINIC
LEAF STRUCTURES SEEN MOVING NE ACROSS THE PLAINS. ONE IS MOVING
FROM CENTRAL NEB INTO CENTRAL SODAK. THIS HAS BEEN INITIALIZED
POORLY BY ALL BUT THE RAP...BUT ALL THIS WAVE LOOKS TO DO IS
EXPAND PRECIPITATION SHIELD A LITTLE FARTHER NW. THE MAIN WAVE CAN
BE SEEN OVER KC...WITH A STRONG PV ANOMALY AND MID LEVEL DRYING
SEEN WITH IT. THIS UPPER WAVE WILL HEAD TOWARD CENTRAL WI AND WILL
HELP DRIVE A SFC LOW FROM KC...UP TO ROCHESTER THEN OVER TO GREEN
BAY. SEEING A NICE TROWAL SIGNATURE WITH THIS WAVE AS WELL...WITH
THE RAP BRINGING THE 1.5 PV SFC DOWN TO ABOUT H5. THIS TROWAL WILL
HELP ENHANCE THE DEFORMATION PRECIP EXPECTED TO MOVE UP INTO WRN
MN...THEN EAST ACROSS CENTRAL MN.
15.06 NAM ALONG WITH THE 15.00 ECMWF LOOK TO HAVE BEST HANDEL ON
DEFORMATION PRECIP BAND CURRENTLY ACROSS ERN NEB...SO FAVORED QPF
AND POP FORECAST INTO TONIGHT HEAVILY ON A BLEND OF THESE TWO
MODELS. FOR SNOWFALL AMOUNTS...IT WILL DEPEND HEAVILY ON HOW
QUICKLY CHANGE OVER TO SNOW OCCURS. FAVOR AN ECMWF NMM/ARW WRF
DEPICTION...WHICH SHOW PRIMARILY RAIN THROUGH 18Z...WITH A
TRANSITION TO MOSTLY SNOW BY 00Z NW OF A GRANITE FALLS TO LITTLE
FALLS LINE...WITH TRANSITION TO SNOW SLOWLY WORKING ACROSS THE CWA
THERE AFTER. AT THE MOMENT HAVE 2-4 INCHES NORTHWEST OF A GRANITE
FALLS TO MORA LINE. THOUGH AS STATED ABOVE..THE EARLIER THE
TRANSITION OCCURS...THE MORE ACCUMULATIONS WOULD OCCUR AND WOULD
NOT COMPLETELY RULE OUT SEEING WARNING TYPE SNOW /6 INCHES OR
MORE/ FROM ALEX OVER TOWARD MORA.
OF COURSE ONE SILVER LINING IN ALL OF THIS...IS THE ENTIRE CWA
LOOKS TO RECEIVE AT LEAST A QUARTER INCH OF QPF...WITH POSSIBLY
MORE THAN A HALF INCH ACROSS WRN MN WITH DEFORMATION BAND AND WRN
WI...WHICH WILL BE CLOSER TO THE LLJ HEADING FOR CENTRAL WI. THIS
WOULD PUT JUST ABOUT ALL LOCATIONS ACROSS THE CWA ABOVE NORMAL ON
LIQUID PRECIPITATION FOR THE MONTH...WHICH WOULD BE THE FIRST TIME
MOST PLACES ACROSS THE MPX AREA WOULD HAVE DONE THAT SINCE MAY OR
JUNE OF THIS YEAR.
BEHIND THIS SYSTEM...THE WEATHER LOOKS DRY AND TRANQUIL FROM
MONDAY THROUGH WEDNESDAY...WITH TEMPERATURES NEAR NORMAL. ONLY
OUTSIDE SHOT AT SOME LIGHT SNOW WOULD COME TUESDAY AS A WEAK WARM
FRONT LIFTS NE INTO THE AREA BEFORE WASHING OUT.
OF MORE CONCERN NEXT WEEK IS WHAT LOOKS TO BE A MAJOR WINTER STORM
THAT WILL BE PLAYING OUT ACROSS THE CENTER OF THE COUNTRY. THE
ECMWF/GFS/FIM ARE ALL IN REMARKABLY GOOD AGREEMENT WITH THIS
SYSTEM FOR 5/6 DAYS OUT...SHOWING A DEEP SFC LOW TRACKING FROM
CENTRAL MO WEDNESDAY NIGHT OVER TOWARD MICHIGAN BY THU AFTERNOON.
THIS WOULD KEEP THE MAJORITY OF PRECIPITATION SOUTH OF THE MPX
CWA...WITH MAINLY THE SE CWA HAVING THE BEST CHANCE AT GETTING
BUZZED BY A COUPLE OF INCHES OF SNOW. GIVEN MODEL AGREEMENT...DID
PUT SOME LIKELY SNOWS IN FOR THE SE CWA. OF MORE CONCERN...
ESPECIALLY WITH THE VERY SIMILAR FIM/ECMWF IS THE SIGNIFICANT
BLIZZARD BOTH TAKE FROM NRN MO/IA...ACROSS NRN IL/SRN WI INTO WRN
MI WEDNESDAY NIGHT/THURSDAY. IF ANY SORT OF NRN SHIFT IS SEEN IN
THE MODELS IN THE COMING DAYS...THEN PARTS OF THE MPX CWA MAY VERY
WELL HAVE TO DEAL WITH WHAT IS CERTAINLY LOOKING TO BE A VERY
SIGNIFICANT WINTER STORM.
BEHIND THIS SYSTEM...WE LOOK TO END THE WEEK ON A COLD NOTE. IN
FACT THE GFS/ECMWF ARE HINTING AT THE WX PATTERN TAKING A TURN FOR
THE SIGNIFICANTLY COLDER AS WE HEAD TOWARD CHRISTMAS...WITH DEEP
TROUGHING ALONG THE EAST COAST AND SHARP RIDGING OVER THE ROCKIES.
THIS WOULD HELP DISLODGE THE BITTERLY COLD AIR THAT HAS BEEN
LOCKED UP AND BUILDING UP OVER AK/CANADA THE LAST SEVERAL WEEKS.
&&
.AVIATION.../18Z TAF ISSUANCE/
BASED ON THE LATEST REGIONAL RADAR/SFC OBS AND THE RAP SHORT TERM
MODEL...DECIDED TO KEEP AXN ALL SNOW THRU THE TAF PERIOD...WITH
RWF/STC SLOWLY CHANGING OVER BY 21-00Z. DEPENDING UPON HOW THE
UPPER SYSTEM BEGINS TO PIVOT ACROSS NW IA...AND THEN NORTHEAST
ACROSS SC/EC MN THIS EVENING WILL DEPEND ON THE CHG OVER AND HOW
MUCH SNOWFALL IS EXPECTED. BEST AREA OF ACCUMULATING SNOWFALL THIS
AFTN WILL BE AXN AS THE MAIN STORM BEGINS TO PIVOT AND THE
PRECIPITATION HOLDS IN WC/CENTRAL MN OVER THE NEXT SEVERAL HRS.
THE DRY SLOT ACROSS SC/SE MN WILL LIKELY AFFECT RNH/MSP/EAU WITH
SEVERAL HRS OF MAINLY -DZ...BUT IFR/LIFR CIGS ARE A GOOD BET. SFC
WINDS WILL REMAIN E/SE ACROSS THE EASTERN FA...THEN MORE NE/N BY
THE LATE AFTN...THEN SHIFTING TO THE W/NW THIS EVENING. AXN/RWF
WILL SEE THE CHG FROM NE/E WINDS TO A MORE N/NW WIND LATER THIS
AFTN...AND CONTINUING OVERNIGHT. BEST TIME PERIOD OF A CHC OF
LIGHT TO MODERATE SNOWFALL AT STC/RNH/MSP WILL BE AFT 00-3Z WITH
SOME 1/2SM SN POSSIBLE ARND 6Z. LATER SHIFTS CAN UPDATE BASED ON
REGIONAL RADAR. EXPECT CONDS TO SLOWLY IMPROVE AFT 09-12Z...BUT
REMAIN IN THE MVFR RANGE.
KMSP...
FIRST BATCH OF -RA/RA WILL DECREASE TO -DZ IN THE NEXT HR OR TWO.
AFT 20-21Z EXPECT A PERIOD OF IFR CIGS AND -DZ. WINDS WILL REMAIN
FROM THE E/SE AND UNDER 10 KTS. WINDS WILL SLOWLY BECOME NE/N THIS
EVENING AS THE SFC LOW MOVES OVERHEAD. BY 3Z EXPECT WINDS TO BE
MORE NW/NNW AND SLIGHTLY INCREASING BY 6Z. CHG OVER TO RASN
MIXTURE WILL OCCUR AFT THE WINDS SHIFT TO THE N/NNW...WITH A
PREDOMINATE PERIOD OF -SN AND 3/4SM VSBYS BETWEEN 3-9Z. AFT
12Z...MOST OF THE ENERGY WITH THIS SYSTEM WILL BE EAST OF
MSP...WITH MVFR CIGS HOLDING THROUGH THE AFTN.
/OUTLOOK FOR KMSP/
SUN AFTN...SLOW IMPROVEMENT. CHC -SN EARLY. NW WIND 5-10 KTS.
MON...VFR CONDS EXPECTED...POSSIBLE MVFR CEILINGS EARLY. NW WIND 5KTS.
TUE...MVFR CIGS WITH -SN POSSIBLE. WINDS AROUND 5 KTS.
WED...VFR. ..JLT..
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR BENTON-
CHISAGO-DOUGLAS-ISANTI-KANABEC-MILLE LACS-MORRISON-POPE-
SHERBURNE-STEARNS-STEVENS-TODD.
WINTER WEATHER ADVISORY UNTIL 6 PM CST THIS EVENING FOR CHIPPEWA-
KANDIYOHI-LAC QUI PARLE-SWIFT-YELLOW MEDICINE.
WI...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR POLK.
&&
$$
MPG/JLT
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
356 PM CST SAT DEC 15 2012
.UPDATE...
.DISCUSSION...
JUST A QUICK REFRESH ON THE POPS AND QPF ACROSS SWRN NEB. NO REAL
CHANGE BUT QPF PLUMES SUGGEST HIGHER CONFIDENCE FORM KOGA SOUTH
THROUGH KIML SO POPS ARE UP SLIGHTLY AND MEASUREABLE QPF IS FCST A
BIT FARTHER NORTH.
&&
.PREV DISCUSSION... /ISSUED 301 PM CST SAT DEC 15 2012/
DISCUSSION...
THE AREA OF WEAK DEFORMATION ACROSS NERN COLO WILL DRIFT EAST
NORTHEAST AND DECAY THIS EVENING. THUS FAR NO SNOW OR RAIN HAS
REACHED THE GROUND DESPITE THE PERSISTENT RADAR RETURNS. LATER
TONIGHT...A SECOND IMPULSE...CURRENTLY ACROSS THE SRN ROCKIES...WILL
LIFT NORTHEAST FORMING A SECOND AREA OF WEAK DEFORMATION WHICH
COULD DRIFT ACROSS SRN NEB AFTER MIDNIGHT PRODUCING LIGHT SNOW.
THE MODELS ARE HAVING A HARD TIME WITH SOME SOLNS SHOWING
DEFORMATION ACROSS THE SAND HILLS AND OTHERS ACROSS SRN NEB.
THE CONSENSUS OF SOLNS SUPPORTS LIGHT SNOW ACROSS SRN NEB. CHANCE
POPS ARE IN PLACE WITH ACCUMULATIONS LESS THAN AN INCH. HPC
SUGGESTED LITTLE OR NO ACCUMULATION ACROSS SWRN NEB. THE ECM
SHOWED 2 INCHES NEAR KOGA...THE GFS SHOWED 5 INCHES NEAR
KIML...THE GEM SHOWED 2 INCHES NEAR KIML AND THE NAM SHOWED AN
INCH ALL OVER THE PLACE. THE RAP HAS BEEN WOBBLING 1 TO 2 INCHES
NORTH AND SOUTH...GENERALLY NEAR OR SOUTH OF INTERSTATE 80.
IT WOULD BE BEST TO WAIT FOR THE RADAR AND SFC OBSERVATIONS TO
LIGHT UP AND THEN GET MORE SPECIFIC WITH POPS AND SNOW AMOUNTS SINCE
THIS IS A FAIRLY COMPACT AREA OF SNOW THE MODELS ARE FORECASTING
TO DEVELOP. THE MODELS ARE SHOWING A WEAK AREA OF ARCTIC HIGH PRESSURE
BUILDING DOWN TONIGHT AND THE PROGRESS OF THAT AIR COULD HAVE A
LOT TO DO WITH THE LOCATION OF THE SNOWFALL. ALSO...THE NAN AND
RUC SHOW RAIN THIS EVENING AHEAD OF THE FRONT..THEN SNOW WHILE THE
GFS IS ALL SNOW.
THIS SYSTEM WILL EXIT THE FCST AREA LATE IN THE DAY SUNDAY MAKING
FOR A COOL DAY AS THE ARCTIC HIGH DRIFTS EAST...LOW PRESSURE
REFORMS ACROSS THE CNTL HIGH PLAINS AND SOUTH WINDS DEVELOP
RECYCLING COLD AIR NORTH.
THE NEXT WEATHER SYSTEM OF INTEREST CROSSES THE FCST AREA TUESDAY
NIGHT THROUGH WEDNESDAY NIGHT. THERE ARE TWO SCENARIOS SHOWN IN THE
MODELS. THE ECM SUGGESTS A MORE SOUTHERLY ROUTE TAKING A LEAD
SHORT WAVE AND DEFORMATION ZONE THROUGH NORTHWEST NEBRASKA
FOLLOWED BY THE MAIN FORCING THROUGH SRN NEB AND KANSAS...MOSTLY
SOUTH AND EAST OF THE FCST AREA. THE GEM AND GFS SUGGEST A MORE
CLASSIC DISTURBANCE CRIS CROSSING THE COLD FRONT PRODUCING LIGHT
SNOW THROUGHOUT THE FCST AREA. THE FCST USED 50 PERCENT OF THE ECM
AND 25 PERCENT OF THE OTHER TWO MODELS. ALL MODELS SHOW WEAK
FRONTOGENESIS ACROSS NW NEB TUESDAY NIGHT. THE ECM QUICKLY DECAYS
THAT FEATURE WHILE THE GEM AND GFS CARRY THAT ACROSS THE FCST
AREA. EITHER WAY...BY THURSDAY MORNING H10-5 THICKNESSES FALL TO
BELOW 520 DM AND H850 TEMPERATURES ARE AROUND MINUS 7C.
AVIATION...
AN AREA OF STUBBORN STRATUS REMAINS ACROSS NORTH CENTRAL NEBRASKA
THIS AFTERNOON...WITH OCCASIONAL -FZDZ REPORTED EARLIER THIS
AFTERNOON NEAR KONL. THINK MOST OF THIS ACTIVITY HAS
ENDED...HOWEVER NEAR TERM MODELS SUGGEST THESE CLOUDS SHOULD REMAIN
ACROSS THIS AREA INTO THE LATE AFTERNOON/EVENING. OTHERWISE FURTHER
WEST...INCREASING CLOUDINESS WILL BE EXPECTED LATER TONIGHT...WITH
THE POTENTIAL OF LIGHT SNOW ACROSS SOUTHWEST NEBRASKA...POSSIBLY
AFFECTING KIML AND KOGA /MAINLY AFTER 06Z/. NOT TOO EXCITED ABOUT
THE PROSPECTS OF THIS ACTIVITY SPILLING OVER TO THE KLBF AND/OR KVTN
TERMINALS OVERNIGHT...BUT SOME NEAR TERM SOLUTIONS WOULD SUGGEST
OTHERWISE. FOR NOW WILL ONLY LOWER TO MVFR AT KLBF AFTER 09Z AND
AMEND IF NEEDED.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
301 PM CST SAT DEC 15 2012
.DISCUSSION...
THE AREA OF WEAK DEFORMATION ACROSS NERN COLO WILL DRIFT EAST
NORTHEAST AND DECAY THIS EVENING. THUS FAR NO SNOW OR RAIN HAS
REACHED THE GROUND DESPITE THE PERSISTENT RADAR RETURNS. LATER
TONIGHT...A SECOND IMPULSE...CURRENTLY ACROSS THE SRN ROCKIES...WILL
LIFT NORTHEAST FORMING A SECOND AREA OF WEAK DEFORMATION WHICH
COULD DRIFT ACROSS SRN NEB AFTER MIDNIGHT PRODUCING LIGHT SNOW.
THE MODELS ARE HAVING A HARD TIME WITH SOME SOLNS SHOWING
DEFORMATION ACROSS THE SAND HILLS AND OTHERS ACROSS SRN NEB.
THE CONSENSUS OF SOLNS SUPPORTS LIGHT SNOW ACROSS SRN NEB. CHANCE
POPS ARE IN PLACE WITH ACCUMULATIONS LESS THAN AN INCH. HPC
SUGGESTED LITTLE OR NO ACCUMULATION ACROSS SWRN NEB. THE ECM
SHOWED 2 INCHES NEAR KOGA...THE GFS SHOWED 5 INCHES NEAR
KIML...THE GEM SHOWED 2 INCHES NEAR KIML AND THE NAM SHOWED AN
INCH ALL OVER THE PLACE. THE RAP HAS BEEN WOBBLING 1 TO 2 INCHES
NORTH AND SOUTH...GENERALLY NEAR OR SOUTH OF INTERSTATE 80.
IT WOULD BE BEST TO WAIT FOR THE RADAR AND SFC OBSERVATIONS TO
LIGHT UP AND THEN GET MORE SPECIFIC WITH POPS AND SNOW AMOUNTS SINCE
THIS IS A FAIRLY COMPACT AREA OF SNOW THE MODELS ARE FORECASTING
TO DEVELOP. THE MODELS ARE SHOWING A WEAK AREA OF ARCTIC HIGH PRESSURE
BUILDING DOWN TONIGHT AND THE PROGRESS OF THAT AIR COULD HAVE A
LOT TO DO WITH THE LOCATION OF THE SNOWFALL. ALSO...THE NAN AND
RUC SHOW RAIN THIS EVENING AHEAD OF THE FRONT..THEN SNOW WHILE THE
GFS IS ALL SNOW.
THIS SYSTEM WILL EXIT THE FCST AREA LATE IN THE DAY SUNDAY MAKING
FOR A COOL DAY AS THE ARCTIC HIGH DRIFTS EAST...LOW PRESSURE
REFORMS ACROSS THE CNTL HIGH PLAINS AND SOUTH WINDS DEVELOP
RECYCLING COLD AIR NORTH.
THE NEXT WEATHER SYSTEM OF INTEREST CROSSES THE FCST AREA TUESDAY
NIGHT THROUGH WEDNESDAY NIGHT. THERE ARE TWO SCENARIOS SHOWN IN THE
MODELS. THE ECM SUGGESTS A MORE SOUTHERLY ROUTE TAKING A LEAD
SHORT WAVE AND DEFORMATION ZONE THROUGH NORTHWEST NEBRASKA
FOLLOWED BY THE MAIN FORCING THROUGH SRN NEB AND KANSAS...MOSTLY
SOUTH AND EAST OF THE FCST AREA. THE GEM AND GFS SUGGEST A MORE
CLASSIC DISTURBANCE CRIS CROSSING THE COLD FRONT PRODUCING LIGHT
SNOW THROUGHOUT THE FCST AREA. THE FCST USED 50 PERCENT OF THE ECM
AND 25 PERCENT OF THE OTHER TWO MODELS. ALL MODELS SHOW WEAK
FRONTOGENESIS ACROSS NW NEB TUESDAY NIGHT. THE ECM QUICKLY DECAYS
THAT FEATURE WHILE THE GEM AND GFS CARRY THAT ACROSS THE FCST
AREA. EITHER WAY...BY THURSDAY MORNING H10-5 THICKNESSES FALL TO
BELOW 520 DM AND H850 TEMPERATURES ARE AROUND MINUS 7C.
&&
.AVIATION...
AN AREA OF STUBBORN STRATUS REMAINS ACROSS NORTH CENTRAL NEBRASKA
THIS AFTERNOON...WITH OCCASIONAL -FZDZ REPORTED EARLIER THIS
AFTERNOON NEAR KONL. THINK MOST OF THIS ACTIVITY HAS
ENDED...HOWEVER NEAR TERM MODELS SUGGEST THESE CLOUDS SHOULD REMAIN
ACROSS THIS AREA INTO THE LATE AFTERNOON/EVENING. OTHERWISE FURTHER
WEST...INCREASING CLOUDINESS WILL BE EXPECTED LATER TONIGHT...WITH
THE POTENTIAL OF LIGHT SNOW ACROSS SOUTHWEST NEBRASKA...POSSIBLY
AFFECTING KIML AND KOGA /MAINLY AFTER 06Z/. NOT TOO EXCITED ABOUT
THE PROSPECTS OF THIS ACTIVITY SPILLING OVER TO THE KLBF AND/OR KVTN
TERMINALS OVERNIGHT...BUT SOME NEAR TERM SOLUTIONS WOULD SUGGEST
OTHERWISE. FOR NOW WILL ONLY LOWER TO MVFR AT KLBF AFTER 09Z AND
AMEND IF NEEDED.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1108 AM CST SAT DEC 15 2012
.AVIATION...18Z KGRI TAF...VFR CONDITIONS ARE EXPECTED TO PREVAIL
AT KGRI FOR THE NEXT 24 HOURS...WITH MAINLY CLOUDY FREE SKIES
THROUGH THE AFTERNOON HOURS...BEFORE THE NEXT SYSTEM BRINGS A BKN
CLD DECK NEAR 10KT THIS EVENING. WHILE THERE IS AN OUTSIDE CHANCE
OF A LIGHT SNOW SHOWER OR FLURRY AS THE BRUNT OF THIS SYSTEM
PASSES BY OVERNIGHT THROUGH EARLY SUNDAY MORNING...CONFIDENCE IS
LOW ENOUGH NOT TO INCLUDED MENTION IN TAF AT THIS TIME.
OTHERWISE...WINDS WILL BE GUSTY AND OUT OF THE NORTH WEST THIS
AFTERNOON...SUBSIDING TO NEAR OR BELOW 8KTS AFTER SUNSET AND
CONTINUING LESS THAN 8-10KT THROUGH THE END OF THE VALID PERIOD.
&&
.PREV DISCUSSION... /ISSUED 522 AM CST SAT DEC 15 2012/
AVIATION...12Z KGRI TAF. LIFR CONDITIONS EXPECTED TO START THE
TAF PERIOD...WITH GRADUALLY IMPROVING CONDITIONS THROUGH THE NEXT
24 HOURS. ALTHOUGH PRECIPITATION HAS PUSHED EAST OF THE
TERMINAL...STRATUS IS MAINTAINING ITS PRESENCE OVER THE AREA AND
IT SHOULD CONTINUE TO DO SO THROUGH MUCH OF THE MORNING. GUIDANCE
SUGGESTS CEILINGS IN THE 400-600FT AGL RANGE WILL PERSIST THROUGH
MIDDAY BEFORE LIFTING. VISIBILITY RESTRICTIONS...TO AROUND
3/4SM...IN BR WILL ALSO BE OBSERVED AT THE TERMINAL UNTIL THE LOW
LEVEL WIND FIELD INCREASES BY 14Z. THE LOW LEVEL WIND FIELD WILL
REMAIN FROM THE NORTHWEST THROUGH MUCH OF THE TAF
PERIOD...SUSTAINED AT AROUND 15KTS AND GUSTING NEAR 20KTS MID-
MORNING THROUGH LATE AFTERNOON.
PREV DISCUSSION... /ISSUED 345 AM CST SAT DEC 15 2012/
SHORT TERM...THROUGH 12Z TUESDAY. EVENING UPPER AIR ANALYSIS
INDICATES A MID LEVEL LOW OVER SOUTHWESTERN KANSAS...WITH
SOUTHWESTERLY TO QUASI-ZONAL MID AND UPPER LEVEL FLOW PERSISTING
ACROSS MUCH OF THE REST OF THE CONUS. MID AND UPPER LEVEL JET
ENERGY EXTENDS FROM TEXAS...NORTHEAST INTO THE MID-MISSISSIPPI
VALLEY AND THEN EAST/SOUTHEAST INTO THE EASTERN CONUS. WITH THE
BULK OF THE JET ENERGY REMAINING SOUTH AND EAST OF THE CENTRAL
PLAINS...MID TO UPPER LEVEL TROPOSPHERIC FLOW IS NOT OVERLY
IMPRESSIVE OVER OUR AREA...MAXING OUT AT AROUND 70KTS NEAR 200MB
PER 00Z SOUNDING DATA FROM KLBF. WATER VAPOR IMAGERY ALSO SHOWS
THE MID LEVEL LOW OVER SOUTHWESTERN KANSAS...MOVING NORTHEAST.
INCREASED MID LEVEL MOISTURE IS NOTED EXTENDING FROM SOUTHERN
TEXAS INTO THE LOWER MISSISSIPPI VALLEY...WITH A MID LEVEL DRY
INTRUSION EXTENDING FROM NORTH TEXAS INTO EASTERN KANSAS. MID
LEVEL DEFORMATION TO THE NORTH/NORTHWEST OF THE MID LEVEL LOW IS
APPARENT OVER PORTIONS OF NEBRASKA AND KANSAS. AT THE SURFACE AN
AREA OF LOW PRESSURE IS NOTED OVER CENTRAL KANSAS...WITH A WARM
FRONT EXTENDING NORTHEAST FROM THE LOW ACROSS NORTH CENTRAL KANSAS
AND SOUTH CENTRAL NEBRASKA. THE LOW LEVEL WIND FIELD ACROSS THE
SOUTHEASTERN HALF OF OUR CWA...WITHIN THE WARM SECTOR OF THIS
SYSTEM...REMAINS FROM THE SOUTHEAST...WITH LOCATIONS FARTHER
NORTHWEST ACROSS THE AREA REPORTING SURFACE WINDS FROM THE NORTH.
RADAR RETURNS FROM KUEX...AS WELL AS GUIDANCE FROM THE RAP AND
NAM...SUGGEST THE PRIMARY AXIS OF MID LEVEL DEFORMATION WILL
CONTINUE PUSHING EAST/NORTHEAST...AWAY FROM OUR AREA THROUGH THE
REST OF TODAY. THE RESULTANT PRECIPITATION SHIELD SHOULD ALSO
CONTINUE MOVING OUT OF THE AREA THIS MORNING...WITH PRECIPITATION
EXPECTED TO BE DONE BY NO LATER THAN 18Z. AS A RESULT...WENT AHEAD
AND CARRIED SLIGHT CHANCE TO CHANCE POPS ACROSS OUR NORTHEAST
12-18Z...WITH DRY CONDITIONS THEREAFTER.
GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL
SUGGEST QUASI-ZONAL MID AND UPPER LEVEL FLOW WILL BE OBSERVED
ACROSS MUCH OF THE CONUS TONIGHT THROUGH MONDAY NIGHT...WITH
MULTIPLE SMALL-SCALE MID LEVEL PERTURBATIONS ADVANCING WITHIN THE
MEAN FLOW OVER THE CENTRAL PLAINS. QPF FIELDS FROM THESE MODELS
ALL SUGGEST LIGHT PRECIPITATION WILL BE POSSIBLE OVER VARIOUS
POINTS ACROSS THE CWA IN ASSOCIATION WITH THESE MID LEVEL
PERTURBATIONS. UNFORTUNATELY LITTLE TO NO MODEL AGREEMENT EXISTS
WITH RESPECT TO WHEN AND WHERE THIS LIGHT PRECIPITATION WILL BE
REALIZED. SO...ALTHOUGH PERIODIC LIGHT PRECIPITATION IS CERTAINLY
WITHIN THE REALM OF POSSIBILITIES THROUGH THE NEXT COUPLE DAYS...A
LACK IN CONFIDENCE WITH RESPECT TO PRECIPITATION TIMING AND
PLACEMENT PREVENTS THE INTRODUCTION OF POPS TO THE FORECAST FOR
TONIGHT THROUGH MONDAY NIGHT.
THE SURFACE LOW...CURRENTLY MOVING ACROSS KANSAS...IS EXPECTED TO
CONTINUE DOING SO TODAY...THUS ALLOWING THE LOW LEVEL WIND FIELD
ACROSS OUR AREA TO BECOME MORE NORTHWESTERLY. DESPITE THIS CHANGE
IN WIND DIRECTION...LOW LEVEL COLD AIR ADVECTION IS NOT EXPECTED
TO BE PARTICULARLY STRONG. DECENT DIABATIC HEATING SHOULD BE
REALIZED TODAY...ESPECIALLY ACROSS OUR SOUTHWEST...AS THE CLOUDS
CLEAR FROM SOUTHWEST TO NORTHEAST AND AS A RESULT...AFTERNOON
HIGHS IN THE 40S TO LOW 50S CERTAINLY SEEM REASONABLE. SOME
INCREASE IN MID TO HIGH LEVEL CLOUDS WILL PROBABLY BE REALIZED
TONIGHT AS THE FIRST IN THE SERIES OF AFOREMENTIONED MID LEVEL
PERTURBATIONS PUSHES OVERHEAD AND GIVEN THIS EXPECTED INCREASE IN
CLOUD COVER...OVERNIGHT TEMPERATURE DROP-OFFS OF 20-25 DEGREES
SEEMS REASONABLE WHICH PRESENTS LOWS GENERALLY IN THE 20S. THE
PASSAGE OF THE MID LEVEL PERTURBATIONS SHOULD ALSO PROMOTE A
SUBTLE INCREASE IN LOW LEVEL COLD AIR ADVECTION...THUS PRESENTING
SLIGHTLY COOLER WEATHER TO FINISH OUT THE SHORT TERM FORECAST
PERIOD. HIGHS IN THE 30S AND 40S ARE CURRENTLY FORECAST BOTH
SUNDAY AND MONDAY AS A RESULT.
LONG TERM...(TUESDAY THROUGH FRIDAY) THE MAIN STORY: BRIEFLY MILD
TUE BEFORE A TRANSITION TO NEAR-NORMAL COLD AND A POTENTIAL
OPPORTUNITY FOR SNOW MID-WEEK.
PATTERN: THE HEMISPHERIC HGT PATTERN WILL CHANGE LITTLE THRU
CHRISTMAS PER CPC ENSEMBLE MULTI-DAY MEANS. THE NAO AND PNA WILL
BOTH REMAIN NEGATIVE...FAVORING TROFS ALONG THE PAC/ATLANTIC
COASTS AND RIDGING OVER THE PLAINS. WE ARE LIKELY TO SEE ONE MORE
POTENT PAC-ORIGIN TROF THE MIDDLE OF NEXT WEEK BEFORE THE BLOCKING
DEVELOPS IN THE LONGWAVE PATTERN AFTER DEC 22. WE`VE NOTED THE
INCREASING HGTS OVER THE ROCKIES IN THE GFS/EC 5-DAY MEANS THE
WEEK OF CHRISTMAS.
TEMPS WILL BE MUCH ABOVE NORMAL TUE AND THEN IT LOOKS LIKE NEAR
NORMAL TEMPS /SUBSTANTIALLY COLDER THAN WE`VE EXPERIENCE THIS MILD
NOV-DEC/ WED-FRI. NO SUBSTANTIAL/BELOW NORMAL COLD IS FORESEEN
THRU CHRISTMAS...BUT THE PATTERN DOES SUGGEST WE FLIRT MORE WITH
SEASONABLE/NEAR-NORMAL TEMPS OVER THE NEXT 10 DAYS. THIS IS
ESPECIALLY TRUE IF LOW PRES ENDS UP BLOCKED OVER ERN CANADA AND
THE CNTRL USA LONGWAVE RIDGE RETROGRADES TO THE ROCKIES AND
AMPLIFIES DOWNSTREAM OF A CUT-OFF LOW FCST OVER THE E PACIFIC.
THIS HGT PATTERN SUGGESTS WE MIGHT SEE PNA EVENTUALLY TURN
POSITIVE TO ACT IN CONCERT WITH THE -NAO.
HAZARDS: WE`RE SEEING A BURGEONING SIGNAL FOR SOME SNOW LATE WED
INTO WED NGT. TOO EARLY TO TELL THE MAGNITUDE BUT THE SLP/H5
HEIGHTS LOOK THREATENING. WHILE IT APPEARS WINTER HEADLINES ARE
CURRENTLY A LOW PROBABILITY...BELIEVE IT/S WORTHY OF INCLUSION IN
THE HWO BECAUSE THE POTENTIAL IS THERE.
PCPN: PROBABILITIES ARE INCREASING FOR A LGT-MDT EVENT WED-WED
NGT.
THE DAILY DETAILS...
TUE: THE WEAK LOW THE 00Z/14 EC HAD /THAT I DISMISSED 24 HRS AGO/
HAS NOW BEEN JOINED BY A HOST OF OTHER 12Z/14 AND 00Z/15 MODELS.
SO IT LOOKS LIKE A WEAK LOW WILL SLIDE DOWN THE DEVELOPING WARM
FRONT ...SHUNTING IT TO OUR S AS IT HEADS E. OVERALL STILL LOOKING
LIKE A NICE DAY...PROBABLY THE PICK OF THE WEEK WITH HIGH TEMPS
10-15F ABOVE NORMAL.
WED-THU: LOOKING SUBSTANTIALLY MORE INTERESTING THAN 24 HRS AGO
WITH THIS TIME FRAME NOW THREATENING SOME MEASURABLE
SNOWFALL...LOOKING ONLY AT SFC PRES AND H5 HEIGHTS. IT/S NOT IN
THE BAG YET BUT THIS COULD SPELL TROUBLE FOR ALL OR PART OF THE
FCST AREA. EVEN PWAT/S ARE FCST HIGHER WITH THE GFS ENSEMBLE MEAN
NOW DRAWING +1 STANDARD DEVIATION PWAT ALL THE WAY UP TO NEB.
THIS SYSTEM MOVED OFF JAPAN FRI AND IS CURRENTLY NEAR THE DATELINE
/SW OF THE ALEUTIANS/ IN WV IMAGERY. THIS TROF WILL TOP THE PAC
SUB-TROPICAL HIGH AND AMPLIFY AS IT MOVES INTO THE LONGWAVE TROF
ALONG THE W COAST. GEM/GFS/EC/UKMET ARE IN UNISON ON SHORTENING
ITS WAVELENGTH VS 24 HRS AGO.
THE GFS AND ITS ENSEMBLE MEMBERS SEEM WAYYY TOO FAR N WITH THEIR
MAX AXIS OF QPF DESPITE ITS SFC LOWS CLOSE TO THE EC. THE 00Z/15
IS THE FIRST EC RUN THAT THREATENS WARNING CRITERIA QPF AND IT HAS
EXCELLENT SLP/H5 SUPPORT FROM ITS ENSEMBLE MEAN.
TEMPS: WED NGT AND THU NGT PUSHED LOW TEMPS DOWN TO BIAS CORRECTED
ALL-BLEND GUIDANCE...IN CONCERT WITH LBF. AND MAY NOT BE LOW
ENOUGH THU NGT IF SNOW COVER MATERIALIZES. IDEAL RADIATING CONDS
UNDER HIGH PRES SUGGEST TEMPS MAY END UP ANOTHER 5-10F COLDER.
WINDS WERE INCREASED ABOVE GUIDANCE WED AFTN-THU AFTN.
THU CLEARING AND COLDER AND THIS NEAR-NORMAL COLD PROBABLY LINGERS
INTO FRI AS THE DEPARTING LOW CUTS OFF OVER THE NE USA.
CLIMATE...GRI HAS FINALLY EXCEEDED 10 INCHES FOR THE YEAR WITH
THIS RAINFALL EVENT. HOWEVER...WITH THE DRIEST YEAR ON RECORD AT
12.01 /1940/...ODDS STILL FAVOR 2012 ENDING UP THE NEW DRIEST YEAR
ON RECORD. PRECIP RECORDS DATE BACK TO 1895 AT GRAND ISLAND.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AVIATION...ROSSI
SHORT TERM...BRYANT
LONG TERM/CLIMATE...HALBLAUB
AREA FORECAST DISCUSSION
NWS HASTINGS NE
522 AM CST SAT DEC 15 2012
.AVIATION...12Z KGRI TAF. LIFR CONDITIONS EXPECTED TO START THE
TAF PERIOD...WITH GRADUALLY IMPROVING CONDITIONS THROUGH THE NEXT
24 HOURS. ALTHOUGH PRECIPITATION HAS PUSHED EAST OF THE
TERMINAL...STRATUS IS MAINTAINING ITS PRESENCE OVER THE AREA AND
IT SHOULD CONTINUE TO DO SO THROUGH MUCH OF THE MORNING. GUIDANCE
SUGGESTS CEILINGS IN THE 400-600FT AGL RANGE WILL PERSIST THROUGH
MIDDAY BEFORE LIFTING. VISIBILITY RESTRICTIONS...TO AROUND
3/4SM...IN BR WILL ALSO BE OBSERVED AT THE TERMINAL UNTIL THE LOW
LEVEL WIND FIELD INCREASES BY 14Z. THE LOW LEVEL WIND FIELD WILL
REMAIN FROM THE NORTHWEST THROUGH MUCH OF THE TAF
PERIOD...SUSTAINED AT AROUND 15KTS AND GUSTING NEAR 20KTS MID-
MORNING THROUGH LATE AFTERNOON.
&&
.PREV DISCUSSION... /ISSUED 345 AM CST SAT DEC 15 2012/
SHORT TERM...THROUGH 12Z TUESDAY. EVENING UPPER AIR ANALYSIS
INDICATES A MID LEVEL LOW OVER SOUTHWESTERN KANSAS...WITH
SOUTHWESTERLY TO QUASI-ZONAL MID AND UPPER LEVEL FLOW PERSISTING
ACROSS MUCH OF THE REST OF THE CONUS. MID AND UPPER LEVEL JET
ENERGY EXTENDS FROM TEXAS...NORTHEAST INTO THE MID-MISSISSIPPI
VALLEY AND THEN EAST/SOUTHEAST INTO THE EASTERN CONUS. WITH THE
BULK OF THE JET ENERGY REMAINING SOUTH AND EAST OF THE CENTRAL
PLAINS...MID TO UPPER LEVEL TROPOSPHERIC FLOW IS NOT OVERLY
IMPRESSIVE OVER OUR AREA...MAXING OUT AT AROUND 70KTS NEAR 200MB
PER 00Z SOUNDING DATA FROM KLBF. WATER VAPOR IMAGERY ALSO SHOWS
THE MID LEVEL LOW OVER SOUTHWESTERN KANSAS...MOVING NORTHEAST.
INCREASED MID LEVEL MOISTURE IS NOTED EXTENDING FROM SOUTHERN
TEXAS INTO THE LOWER MISSISSIPPI VALLEY...WITH A MID LEVEL DRY
INTRUSION EXTENDING FROM NORTH TEXAS INTO EASTERN KANSAS. MID
LEVEL DEFORMATION TO THE NORTH/NORTHWEST OF THE MID LEVEL LOW IS
APPARENT OVER PORTIONS OF NEBRASKA AND KANSAS. AT THE SURFACE AN
AREA OF LOW PRESSURE IS NOTED OVER CENTRAL KANSAS...WITH A WARM
FRONT EXTENDING NORTHEAST FROM THE LOW ACROSS NORTH CENTRAL KANSAS
AND SOUTH CENTRAL NEBRASKA. THE LOW LEVEL WIND FIELD ACROSS THE
SOUTHEASTERN HALF OF OUR CWA...WITHIN THE WARM SECTOR OF THIS
SYSTEM...REMAINS FROM THE SOUTHEAST...WITH LOCATIONS FARTHER
NORTHWEST ACROSS THE AREA REPORTING SURFACE WINDS FROM THE NORTH.
RADAR RETURNS FROM KUEX...AS WELL AS GUIDANCE FROM THE RAP AND
NAM...SUGGEST THE PRIMARY AXIS OF MID LEVEL DEFORMATION WILL
CONTINUE PUSHING EAST/NORTHEAST...AWAY FROM OUR AREA THROUGH THE
REST OF TODAY. THE RESULTANT PRECIPITATION SHIELD SHOULD ALSO
CONTINUE MOVING OUT OF THE AREA THIS MORNING...WITH PRECIPITATION
EXPECTED TO BE DONE BY NO LATER THAN 18Z. AS A RESULT...WENT AHEAD
AND CARRIED SLIGHT CHANCE TO CHANCE POPS ACROSS OUR NORTHEAST
12-18Z...WITH DRY CONDITIONS THEREAFTER.
GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC AND SREF-MEAN ALL
SUGGEST QUASI-ZONAL MID AND UPPER LEVEL FLOW WILL BE OBSERVED
ACROSS MUCH OF THE CONUS TONIGHT THROUGH MONDAY NIGHT...WITH
MULTIPLE SMALL-SCALE MID LEVEL PERTURBATIONS ADVANCING WITHIN THE
MEAN FLOW OVER THE CENTRAL PLAINS. QPF FIELDS FROM THESE MODELS
ALL SUGGEST LIGHT PRECIPITATION WILL BE POSSIBLE OVER VARIOUS
POINTS ACROSS THE CWA IN ASSOCIATION WITH THESE MID LEVEL
PERTURBATIONS. UNFORTUNATELY LITTLE TO NO MODEL AGREEMENT EXISTS
WITH RESPECT TO WHEN AND WHERE THIS LIGHT PRECIPITATION WILL BE
REALIZED. SO...ALTHOUGH PERIODIC LIGHT PRECIPITATION IS CERTAINLY
WITHIN THE REALM OF POSSIBILITIES THROUGH THE NEXT COUPLE DAYS...A
LACK IN CONFIDENCE WITH RESPECT TO PRECIPITATION TIMING AND
PLACEMENT PREVENTS THE INTRODUCTION OF POPS TO THE FORECAST FOR
TONIGHT THROUGH MONDAY NIGHT.
THE SURFACE LOW...CURRENTLY MOVING ACROSS KANSAS...IS EXPECTED TO
CONTINUE DOING SO TODAY...THUS ALLOWING THE LOW LEVEL WIND FIELD
ACROSS OUR AREA TO BECOME MORE NORTHWESTERLY. DESPITE THIS CHANGE
IN WIND DIRECTION...LOW LEVEL COLD AIR ADVECTION IS NOT EXPECTED
TO BE PARTICULARLY STRONG. DECENT DIABATIC HEATING SHOULD BE
REALIZED TODAY...ESPECIALLY ACROSS OUR SOUTHWEST...AS THE CLOUDS
CLEAR FROM SOUTHWEST TO NORTHEAST AND AS A RESULT...AFTERNOON
HIGHS IN THE 40S TO LOW 50S CERTAINLY SEEM REASONABLE. SOME
INCREASE IN MID TO HIGH LEVEL CLOUDS WILL PROBABLY BE REALIZED
TONIGHT AS THE FIRST IN THE SERIES OF AFOREMENTIONED MID LEVEL
PERTURBATIONS PUSHES OVERHEAD AND GIVEN THIS EXPECTED INCREASE IN
CLOUD COVER...OVERNIGHT TEMPERATURE DROP-OFFS OF 20-25 DEGREES
SEEMS REASONABLE WHICH PRESENTS LOWS GENERALLY IN THE 20S. THE
PASSAGE OF THE MID LEVEL PERTURBATIONS SHOULD ALSO PROMOTE A
SUBTLE INCREASE IN LOW LEVEL COLD AIR ADVECTION...THUS PRESENTING
SLIGHTLY COOLER WEATHER TO FINISH OUT THE SHORT TERM FORECAST
PERIOD. HIGHS IN THE 30S AND 40S ARE CURRENTLY FORECAST BOTH
SUNDAY AND MONDAY AS A RESULT.
LONG TERM...(TUESDAY THROUGH FRIDAY) THE MAIN STORY: BRIEFLY MILD
TUE BEFORE A TRANSITION TO NEAR-NORMAL COLD AND A POTENTIAL
OPPORTUNITY FOR SNOW MID-WEEK.
PATTERN: THE HEMISPHERIC HGT PATTERN WILL CHANGE LITTLE THRU
CHRISTMAS PER CPC ENSEMBLE MULTI-DAY MEANS. THE NAO AND PNA WILL
BOTH REMAIN NEGATIVE...FAVORING TROFS ALONG THE PAC/ATLANTIC
COASTS AND RIDGING OVER THE PLAINS. WE ARE LIKELY TO SEE ONE MORE
POTENT PAC-ORIGIN TROF THE MIDDLE OF NEXT WEEK BEFORE THE BLOCKING
DEVELOPS IN THE LONGWAVE PATTERN AFTER DEC 22. WE`VE NOTED THE
INCREASING HGTS OVER THE ROCKIES IN THE GFS/EC 5-DAY MEANS THE
WEEK OF CHRISTMAS.
TEMPS WILL BE MUCH ABOVE NORMAL TUE AND THEN IT LOOKS LIKE NEAR
NORMAL TEMPS /SUBSTANTIALLY COLDER THAN WE`VE EXPERIENCE THIS MILD
NOV-DEC/ WED-FRI. NO SUBSTANTIAL/BELOW NORMAL COLD IS FORESEEN
THRU CHRISTMAS...BUT THE PATTERN DOES SUGGEST WE FLIRT MORE WITH
SEASONABLE/NEAR-NORMAL TEMPS OVER THE NEXT 10 DAYS. THIS IS
ESPECIALLY TRUE IF LOW PRES ENDS UP BLOCKED OVER ERN CANADA AND
THE CNTRL USA LONGWAVE RIDGE RETROGRADES TO THE ROCKIES AND
AMPLIFIES DOWNSTREAM OF A CUT-OFF LOW FCST OVER THE E PACIFIC.
THIS HGT PATTERN SUGGESTS WE MIGHT SEE PNA EVENTUALLY TURN
POSITIVE TO ACT IN CONCERT WITH THE -NAO.
HAZARDS: WE`RE SEEING A BURGEONING SIGNAL FOR SOME SNOW LATE WED
INTO WED NGT. TOO EARLY TO TELL THE MAGNITUDE BUT THE SLP/H5
HEIGHTS LOOK THREATENING. WHILE IT APPEARS WINTER HEADLINES ARE
CURRENTLY A LOW PROBABILITY...BELIEVE IT/S WORTHY OF INCLUSION IN
THE HWO BECAUSE THE POTENTIAL IS THERE.
PCPN: PROBABILITIES ARE INCREASING FOR A LGT-MDT EVENT WED-WED
NGT.
THE DAILY DETAILS...
TUE: THE WEAK LOW THE 00Z/14 EC HAD /THAT I DISMISSED 24 HRS AGO/
HAS NOW BEEN JOINED BY A HOST OF OTHER 12Z/14 AND 00Z/15 MODELS.
SO IT LOOKS LIKE A WEAK LOW WILL SLIDE DOWN THE DEVELOPING WARM
FRONT ...SHUNTING IT TO OUR S AS IT HEADS E. OVERALL STILL LOOKING
LIKE A NICE DAY...PROBABLY THE PICK OF THE WEEK WITH HIGH TEMPS
10-15F ABOVE NORMAL.
WED-THU: LOOKING SUBSTANTIALLY MORE INTERESTING THAN 24 HRS AGO
WITH THIS TIME FRAME NOW THREATENING SOME MEASURABLE
SNOWFALL...LOOKING ONLY AT SFC PRES AND H5 HEIGHTS. IT/S NOT IN
THE BAG YET BUT THIS COULD SPELL TROUBLE FOR ALL OR PART OF THE
FCST AREA. EVEN PWAT/S ARE FCST HIGHER WITH THE GFS ENSEMBLE MEAN
NOW DRAWING +1 STANDARD DEVIATION PWAT ALL THE WAY UP TO NEB.
THIS SYSTEM MOVED OFF JAPAN FRI AND IS CURRENTLY NEAR THE DATELINE
/SW OF THE ALEUTIANS/ IN WV IMAGERY. THIS TROF WILL TOP THE PAC
SUB-TROPICAL HIGH AND AMPLIFY AS IT MOVES INTO THE LONGWAVE TROF
ALONG THE W COAST. GEM/GFS/EC/UKMET ARE IN UNISON ON SHORTENING
ITS WAVELENGTH VS 24 HRS AGO.
THE GFS AND ITS ENSEMBLE MEMBERS SEEM WAYYY TOO FAR N WITH THEIR
MAX AXIS OF QPF DESPITE ITS SFC LOWS CLOSE TO THE EC. THE 00Z/15
IS THE FIRST EC RUN THAT THREATENS WARNING CRITERIA QPF AND IT HAS
EXCELLENT SLP/H5 SUPPORT FROM ITS ENSEMBLE MEAN.
TEMPS: WED NGT AND THU NGT PUSHED LOW TEMPS DOWN TO BIAS CORRECTED
ALL-BLEND GUIDANCE...IN CONCERT WITH LBF. AND MAY NOT BE LOW
ENOUGH THU NGT IF SNOW COVER MATERIALIZES. IDEAL RADIATING CONDS
UNDER HIGH PRES SUGGEST TEMPS MAY END UP ANOTHER 5-10F COLDER.
WINDS WERE INCREASED ABOVE GUIDANCE WED AFTN-THU AFTN.
THU CLEARING AND COLDER AND THIS NEAR-NORMAL COLD PROBABLY LINGERS
INTO FRI AS THE DEPARTING LOW CUTS OFF OVER THE NE USA.
CLIMATE...GRI HAS FINALLY EXCEEDED 10 INCHES FOR THE YEAR WITH
THIS RAINFALL EVENT. HOWEVER...WITH THE DRIEST YEAR ON RECORD AT
12.01 /1940/...ODDS STILL FAVOR 2012 ENDING UP THE NEW DRIEST YEAR
ON RECORD. PRECIP RECORDS DATE BACK TO 1895 AT GRAND ISLAND.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AVIATION/SHORT TERM...BRYANT
LONG TERM/CLIMATE...HALBLAUB
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
348 PM EST SAT DEC 15 2012
.SYNOPSIS...
LOW PRESSURE OVER IOWA WILL MOVE NORTHEAST TO THE NORTHERN GREAT
LAKES THROUGH SUNDAY. ANOTHER LOW PRESSURE WILL TRACK NORTHEAST
FROM THE OHIO VALLEY TO NORTHEAST OHIO MONDAY NIGHT...THEN TO THE
NORTHEAST ON TUESDAY. HIGH PRESSURE WILL BUILD INTO THE AREA FOR
MID WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
RADAR SHOWING AN AREA OF SHOWERS FROM SRN MI EXTENDING SOUTHWARD
OVER WESTERN OHIO THIS AFTERNOON. HOWEVER...OBS INDICATING NOT
MUCH FOR PRECIP REACHING THE GROUND. 12Z SOUNDINGS FROM DTX AND
PIT SHOWING A LOT OF DRY AIR IN PLACE AT MID LEVELS WHICH THE
PRECIP WILL HAVE TO MOISTEN UP BEFORE REACHING THE GROUND. SOME
OBS HAVE INDICATED SOME SHOWERS HAVE FINALLY REACHED THE GROUND AT
SEVERAL SPOTS OVER WRN OH FROM TOL-FDY-AOH. SE SFC WINDS ALSO
KEEPING DRIER AIR IN PLACE OVER N CENTRAL AND NE OH.
FOR THIS EVENING WENT WITH THE HIGHER MET POPS ACROSS THE AREA
THINKING THAT THERE IS A GOOD CHANCE THAT MOST AREA WILL SEE SOME
SHOWERS. QPFS WILL NOT BE VERY MUCH AND IT MAY BE SHORT
LIVED...DIMINISHING AFTER 04-06Z ACROSS THE EAST WITH ONLY LOW CHC
POPS ACROSS THE AREA AFTER THAT. AFTER 06Z HIGHEST CHC POPS WILL
BE ACROSS NRN COUNTIES AND LAKE ERIE. KEPT LOW CHC POPS ACROSS THE
REMAINDER OF THE AREA TO ACCOUNT FOR SOME SHOWERS BUT CONFIDENCE
LOWER FOR WIDESPREAD ACTIVITY THEN.
WENT WITH A NON-DIURNAL TREND ON TEMPS TONIGHT. ALL MOS GUIDANCE
TEMP TENDS LEANING TOWARD EARLY NIGHT LOWS FROM AROUND
00-03Z...THEN RISING OVERNIGHT. GIVEN THE SFC PATTERN THIS IS VERY
REASONABLE. MOST LOCATIONS INDICATE TEMPS RISING AFTER MIDNIGHT.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY NIGHT/...
LOW PRESSURE WILL BE OVER THE NORTHERN GREAT LAKES ON SUNDAY. COLD
FRONT ASSOCIATED WITH THE LOW WILL REMAIN WEST OF THE AREA.
LOOKING UPSTREAM NOTING A DRY SLOT ON THE SOUTH SIDE OF THE
LOW...WHICH MAY GET INTO PORTIONS OF THE AREA ON SUNDAY. WHILE
THERE MAY BE SOME LINGERING CLOUDS...KEPT POPS ON THE LOW SIDE
WHICH MATCH CLOSER TO GUIDANCE RANGING FROM SLGT CHC TO LOW CHC.
DIDN/T WANT TO COMPLETELY RULE OUT THE CHC FOR A FEW SHOWERS
AROUND...BUT MORE ORGANIZED PRECIP APPEARS TO BE TO THE NORTH.
LOOKS TO BE MAINLY QUIET WITH ONLY SMALL CHANCES FOR SHOWERS
SUNDAY NIGHT AND MONDAY AS THE AREA EXPERIENCES A SMALL BREAK IN
BETWEEN SYSTEMS. MODELS COMING TOGETHER WITH THE NEXT LOW TRACKING
TOWARD THE AREA BY LATE MONDAY AND MONDAY NIGHT. FOR NOW KEPT THE
MENTION OF SOME RAIN AND SNOW IN THE FORECAST. THICKNESS AND H850
TEMPS APPEAR TO BE CLOSE...BUT GOING FROM LATEST MODELS THE
PREFERRED PRECIP TYPE WOULD BE RAIN. GIVEN THE UNCERTAINLY
CONTINUED WITH THE COMBINATION OF RAIN/SNOW ACROSS CENTRAL AND
WESTERN AREAS. LOW PRESSURE APPEARS TO BE QUICK MOVING AND THE
AREA WILL SEE DRYING CONDITIONS FROM WEST TO EAST THROUGH EARLY
TUESDAY NIGHT.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
HE WEATHER IS UNSETTLED THROUGH THE PERIOD. THE MODELS HAVE THE
SAME IDEA BUT SOME MODERATE MODEL DIFFERENCES.
WEDNESDAY WILL BE IN THE IN BETWEEN DAY WITH GENERALLY DRY WEATHER.
HOWEVER...SOME SNOW SHOWERS COULD BE LINGERING IN THE MORNING IN
NORTHWEST PENNSYLVANIA.
THE NEXT LOW WILL BE HEADING TOWARD THE AREA WEDNESDAY NIGHT. THE
ECMWF IS SLOWER THAN THE GFS...USED A BLEND AND DID INTRODUCE A
CHANCE IN THE WEST WEDNESDAY NIGHT. WENT WITH LIKELY POPS ON
THURSDAY AS THE LOW MOVES JUST NORTHWEST OF THE AREA AND THE COLDER
AIR POURS IN. WITH TIMING DIFFERENCES HAD TO HAVE MIXED
PRECIPITATION THURSDAY THROUGH THURSDAY EVENING.
FOR FRIDAY THROUGH SATURDAY THE GFS IS BACKING DOWN ON THE
MOISTURE...WHILE THE ECMWF HAS COPIOUS AMOUNTS ACROSS THE ENTIRE
AREA AND A MORE NORTHWEST FLOW. THE MOISTURE DOES SEEM OVERDONE FROM
THE ECMWF...SO BACKED DOWN ON THE POPS OVER NORTHWEST OHIO. THE
THREAT OF SNOW SHOWERS WILL BE DECREASING SATURDAY...ESPECIALLY
LATER IN THE DAY.
USED A BLEND OF MOS GUIDANCE AND HPC FOR THE TEMPERATURES.
&&
.AVIATION /21Z SATURDAY THROUGH THURSDAY/...
THE VFR WEATHER WILL BE ENDING THIS EVENING. SHOWERS AND CLOUDS
ARE ON THE INCREASE NEAR A WARM FRONT THAT WILL BE MOVING ACROSS
THE REGION THIS AFTERNOON AND EVENING. THE ROUND OF SHOWERS THAT
WILL MOVE ACROSS THE AREA THROUGH THIS EVENING SHOULD BE MAINLY
VFR...THE HRRR MODEL SEEMS TO HAVE A GOOD HANDLE ON THINGS. HOWEVER...ITS
TIMING COULD BE A LITTLE QUICK. CONDITIONS WILL DETERIORATE TO MVFR
CEILINGS IF NOT IFR TONIGHT. VERY CONFIDENT IN THE MVFR CEILINGS AND ONLY
MODERATELY CONFIDENT IN THE IFR CEILINGS. THE BEST CHANCE FOR THAT
WILL BE INLAND OF THE LAKE AND OVER NORTHWEST OHIO. CONDITIONS
WILL IMPROVE TO NEAR 3000 FOOT CEILINGS BY EARLY SUNDAY AFTERNOON.
THE WINDS AT THE SURFACE WILL INCREASE SOME AND COULD GUST TO 20
KNOTS TONIGHT. THIS WILL HELP KEEP THE THREAT OF LLWS LOWER AS THE
WINDS AT 2000 FEET WILL BE NEAR 40 KNOTS...IT MEANS SOME
MECHANICAL TURBULENCE. THE WIND WILL ALSO HELP WITH THE
VISIBILITY...SOME 5SM MAY STILL OCCUR.
OUTLOOK...NON VFR PROBABLE MONDAY THROUGH TUESDAY AND THEN AGAIN
ON THURSDAY.
&&
.MARINE...
A WARM FRONT WILL MOVE NORTH OF THE LAKE TONIGHT. WITH A SOUTHEAST
FLOW THE WINDS COULD BE IN THE 15 TO 25 KNOT RANGE MAINLY ON THE
EAST END EVEN WITH THE LAKE TEMPERATURE NEAR THE 850 MB TEMPERATURE.
ISSUED A SMALL CRAFT ADVISORY FOR LATE THIS EVENING THROUGH SUNDAY
MORNING.
A FRONT WILL MOVE ACROSS THE LAKE SUNDAY NIGHT AND THEN A LOW WILL
MOVE ALONG THE FRONT MONDAY INTO MONDAY NIGHT. THIS WILL HAVE TO BE
MONITORED FOR A POSSIBLE SMALL CRAFT ADVISORY...DEPENDING ON THE
EXACT TRACK AND STRENGTH OF THE LOW.
WEDNESDAY SHOULD BE QUIET WEATHER ON THE LAKE. THEN WE WILL HAVE TO
WATCH THE NEXT WEATHER SYSTEM FOR THURSDAY INTO SATURDAY AS THE LOW
MOVES UP THROUGH THE CENTRAL LAKES. SOME BIG MODEL DIFFERENCES...IF
THE GFS IS CORRECT GALE FORCE WINDS ARE A STRONG POSSIBILITY
POSSIBLE LATE IN THE WEEK. MANY QUESTIONS AT THIS TIME...THIS WILL
HAVE TO BE MONITORED.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 10 AM EST
SUNDAY FOR LEZ147>149.
&&
$$
SYNOPSIS...ABE
NEAR TERM...ABE
SHORT TERM...ABE
LONG TERM...KIELTYKA
AVIATION...KIELTYKA
MARINE...KIELTYKA
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1257 PM EST SAT DEC 15 2012
.SYNOPSIS...
LOW PRESSURE MOVING FROM THE MISSISSIPPI VALLEY TO THE GREAT LAKES
WILL SPREAD OFF AND ON SHOWERS AND WARMER AIR ACROSS THE AREA
THIS WEEKEND. ANOTHER LOW PRESSURE CENTER IS EXPECTED TO DEVELOP
OVER THE OHIO VALLEY ON MONDAY AND MOVE OFF THE EAST COAST BY
TUESDAY. HIGH PRESSURE AND COOLER AIR WILL MOVE IN BY MID WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
RADAR SHOWING RETURNS MOVING INTO THE FORECAST AREA THIS
AFTERNOON. BAND ACROSS N CNTRL OH MAINLY ALOFT...BUT OBS SHOWING
SOME SHOWERS REACHING THE GROUND WITH ANOTHER BAND OVER NW OH AT
TOL. MADE SOME ADJUSTMENTS TO POPS THIS AFTERNOON BUT NOTHING
MAJOR. CONTINUED WITH CATEGORICAL AND LIKELY ACROSS THE WEST...BUT
HELD BACK ON BRINGING ACTIVITY TOO FAR EAST INTO THE AREA UNTIL
TONIGHT. TEMPS TRENDING WELL WITH EARLIER CHANGE WORKING WELL
ACROSS THE SOUTHWEST.
PREVIOUS DISCUSSION....THE SURFACE LOW IS PROGGED TO WEAKEN AS IT
TRACKS TO THE WESTERN GREAT LAKES BY SUNDAY. NICE SURGE OF WARM
ADVECTION AND ISENTROPIC LIFT MOVING NORTH UP THE MS VALLEY AND
OHIO VALLEY EARLY THIS MORNING. NOT A LOT OF RAIN SHOWING UP IN
THE METARS UNTIL YOU GET BACK TO THE MS VALLEY AND IT IS LIGHT. WE
WILL LIKELY SEE RADAR RETURNS FOR A WHILE BEFORE ANYTHING REACHES
THE GROUND. THE JET IS PRETTY FAR SOUTH...COMING OUT OF THE DESERT
SOUTHWEST. THE LEFT EXIT REGION REACHES NORTHERN OHIO BY LATE
AFTERNOON AND MAY JUST BE THE TRIGGER WE NEED TO GET ENOUGH UPWARD
MOTION TO MOISTEN THE LOWER LAYERS. WILL INCREASE THE PROBABILITY
OF PRECIPITATION LATER IN THE DAY FROM WEST TO EAST.
THE HIGH CLOUDS IN ADVANCE OF THE SYSTEM WILL THICKEN AND LOWER BUT
WE MAY GET SOME FILTERED SUNSHINE THIS MORNING. THE LACK OF
RAIN FOR A WHILE TODAY WILL ALLOW TEMPS TO RISE ABOVE WHAT WE SAW
YESTERDAY EXCEPT MAYBE ACROSS THE I-75 CORRIDOR WHERE THE SHOWERS
WILL ARRIVE FIRST. HIGHS MOSTLY IN THE UPPER 40S TO AROUND 50.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
A SERIES OF WAVES IS PROGGED OUT OF THE TROUGH THROUGH EARLY NEXT
WEEK. A WEAK WAVE IS LIKELY ON SUNDAY...SUNDAY NIGHT...THEN A
STRONGER WAVE BY MONDAY NIGHT. WE WILL NOT BE IN THE SWEET SPOT TO
MAXIMIZE THE RAIN SINCE THE JET WILL REMAIN TO OUR SOUTH AND SOME
MID AND LOW LEVEL DRYING WILL OCCUR. WILL KEEP THE POP RATHER
LOW...CHANCE OR SLIGHT CHANCE... FOR TONIGHT THROUGH SUNDAY
NIGHT...THEN HIGHER POPS ACROSS NE OH/NW PA LATER MONDAY AND MONDAY
NIGHT AS THE TROUGH SHARPENS. RIDGING AT THE SURFACE AND ALOFT WILL
BUILD IN MID WEEK.
THE WARM SOUTH WINDS AND RISING TEMPERATURES WILL BE INTERRUPTED
ONLY BY THE SHOWERS LATER TODAY INTO TONIGHT AND DARKNESS. WE SHOULD
SEE 50S ON SUNDAY AND WITH DEWPOINTS RISING AS WELL IT WILL SEEM
MORE LIKE EARLY SPRING THAN EARLY WINTER. WEAK COLD ADVECTION WILL
DEVELOP SUNDAY NIGHT INTO MONDAY BUT DO NOT EXPECT MUCH COOLING
UNTIL THE NEXT WAVE AND TROUGH PASSES THROUGH MONDAY NIGHT INTO
TUESDAY. TEMPERATURES WILL NOT COOL SIGNIFICANTLY UNTIL TUESDAY
NIGHT BUT PROBABLY STILL REMAIN A BIT ABOVE NORMAL INTO MID WEEK.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
UPPER LEVEL PATTERN STILL TRENDING TOWARD RIDGE BUILDING IN THE
CENTRAL UNITED STATES AND PROGRESSING EAST THROUGH THE PERIOD. THE
UPPER LEVEL RIDGE WILL AMPLIFY DRAMATICALLY BY THURSDAY AS VIGOROUS
VORTICITY MAXIMUM DIVES INTO THE BASE OF THE WEST COAST TROUGH. THIS
WILL CAUSE THE TROUGH TO DIG FURTHER SOUTH AND BECOME SOMEWHAT
NEGATIVELY TILTED. STRONG UPPER LEVEL LOW PRESSURE WILL DEVELOP IN
THE BASE OF THE TROUGH RESULTING IN POTENTIAL FOR RAPID CYCLOGENESIS
TO OCCUR AT THE SURFACE OVER THE MID MISSISSIPPI VALLEY REGION. THE
DEEP SURFACE LOW WILL TRACK NORTHEAST OVER OHIO INTO PENNSYLVANIA BY
FRIDAY EVENING. THE LOW WILL TAP INTO SOME ARCTIC AIR TO THE NORTH
AND HAVE FAIRLY DEEP BROAD MOISTURE ASSOCIATED WITH IT. ONCE THE
COLD AIR ADVECTION BEGINS...THIS WILL SET UP THE POTENTIAL FOR SOME
OF THE COLDEST AIR OF THE SEASON TO ARRIVE IN THE FORECAST AREA FOR
THE WEEKEND INTO CHRISTMAS.
WILL TRANSITION FROM WEAK HIGH PRESSURE OVER THE AREA ON WEDNESDAY
INTO SOME RAIN ON THURSDAY AS THE LOW MOVES EAST ACROSS THE AREA.
THEN...ONCE COLDER AIR ARRIVES...THE RAIN WILL SWITCH OVER TO SNOW.
THERE IS THE POSSIBILITY THAT MANY AREAS WILL SEE THEIR FIRST
MEASURABLE SNOWFALL OF THE SEASON PROVIDED THE MODELS CONTINUE TO
HOLD ON TO THIS STORM SYSTEM IN ITS PRESENT FORM.
LOOKING FURTHER DOWN THE ROAD INTO THE WEEKEND AND
CHRISTMAS...POSSIBILITY EXISTS THAT LAKE EFFECT SNOW WILL CONTINUE
INTO MONDAY WITH LITTLE IN THE WAY OF WARM UP EXPECTED. WILL KEEP AN
EYE ON THIS PATTERN TO SEE HOW IT DEVELOPS.
&&
.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
THE VFR WEATHER WILL BE ENDING THIS EVENING. SHOWERS AND CLOUDS
ARE ON THE INCREASE NEAR A WARM FRONT THAT WILL BE MOVING ACROSS
THE REGION THIS AFTERNOON AND EVENING. THE ROUND OF SHOWERS THAT
WILL MOVE ACROSS THE AREA THROUGH THIS EVENING SHOULD BE MAINLY
VFR...THE HRRR MODEL SEEMS TO HAVE A GOOD HANDLE ON THINGS. HOWEVER...ITS
TIMING COULD BE A LITTLE QUICK. CONDITIONS WILL DETERIORATE TO MVFR
CEILINGS IF NOT IFR TONIGHT. VERY CONFIDENT IN THE MVFR CEILINGS AND ONLY
MODERATELY CONFIDENT IN THE IFR CEILINGS. THE BEST CHANCE FOR THAT
WILL BE INLAND OF THE LAKE AND OVER NORTHWEST OHIO. CONDITIONS
WILL IMPROVE TO NEAR 3000 FOOT CEILINGS BY EARLY SUNDAY AFTERNOON.
THE WINDS AT THE SURFACE WILL INCREASE SOME AND COULD GUST TO 20
KNOTS TONIGHT. THIS WILL HELP KEEP THE THREAT OF LLWS LOWER AS THE
WINDS AT 2000 FEET WILL BE NEAR 40 KNOTS...IT MEANS SOME
MECHANICAL TURBULENCE. THE WIND WILL ALSO HELP WITH THE
VISIBILITY...SOME 5SM MAY STILL OCCUR.
OUTLOOK...NON VFR PROBABLE MONDAY THROUGH TUESDAY AND THEN AGAIN
ON THURSDAY.
&&
.MARINE...
LAKE LOOKS LIKE IT SHOULD BE RELATIVELY QUIET THROUGH AT LEAST
MONDAY. A SERIES OF LOW PRESSURE SYSTEMS WILL MOVE NORTHEAST ACROSS
THE LAKE BUT KEEP THE FLOW PRIMARY FROM THE SOUTHERN HALF OF THE
COMPASS. THIS SHOULD KEEP THE HIGHER WAVES WELL OFF THE COAST AND
NEGATE ANY NEED FOR SMALL CRAFT ADVISORIES THROUGH MONDAY. THIS WILL
CHANGE ON TUESDAY WHEN GRADIENT TIGHTENS AND WINDS INCREASE OUT OF
THE WEST. THIS IS WHEN SMALL CRAFT ADVISORIES WILL LIKELY NEED TO BE
HOISTED AND WILL CONTINUE INTO WEDNESDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
PA...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...KOSARIK
NEAR TERM...ABE/KOSARIK
SHORT TERM...KOSARIK
LONG TERM...LOMBARDY
AVIATION...KIELTYKA
MARINE...LOMBARDY
AREA FORECAST DISCUSSION
NWS NORMAN OK
1153 AM CST SAT DEC 15 2012
.UPDATE...
PRIMARY UPDATES THIS MORNING WERE TO LOWER FORECAST MAX
TEMPERATURES A COUPLE OF DEGREES IN THE SOUTH WHERE CIRRUS IS A
BIT THICKER... AND TO LOWER WIND SPEEDS A TOUCH. DEWPOINTS ARE
HANGING ON MUCH HIGHER THAN THE FORECAST OR MOST OF THE MODELS
HAVE BEEN FORECASTING... ALTHOUGH THE MORNING SOUNDING WOULD
SUGGEST THAT DEWPOINTS SHOULD MIX OUT TO LOWER VALUES AS HEATING
CONTINUES. RAP DOES MAINTAIN THE HIGHER DEWPOINTS TODAY THOUGH.
HAVE ADJUSTED DEWPOINTS UP BASED ON THE CURRENT OBSERVATIONS AND
TRENDS... AND HAVE SPLIT THE DIFFERENCE BETWEEN THE RAP AND NAM
MOVING FORWARD TODAY AND TONIGHT. THIS KEEPS MINIMUM AFTERNOON RH
ABOVE 20 PERCENT IN ALL BUT THE FAR SOUTHERN PORTION OF THE AREA.
WILL CANCEL RED FLAG WARNING IN OKLAHOMA AND HARDEMAN COUNTY
TEXAS... BUT LEAVE IT IN THE REST OF WESTERN NORTH TEXAS.
&&
.PREV DISCUSSION... /ISSUED 1123 AM CST SAT DEC 15 2012/
AVIATION...
15/18Z TAFS...VFR CONDITIONS WILL PREVAIL. GUSTY SOUTHWEST WINDS
ACROSS SOUTHWEST OKLAHOMA AND NORTH TEXAS TERMINALS WILL SUBSIDE
TOWARD AND AFTER 00Z. WEAK FRONTAL BOUNDARY WILL PASS OVER
NORTHWEST AND WEST-CENTRAL OKLAHOMA TERMINALS 15-18Z TOMORROW
SHIFTING WINDS TO NORTHWEST.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 64 39 61 33 / 0 0 0 0
HOBART OK 62 36 59 30 / 0 0 0 0
WICHITA FALLS TX 70 43 69 36 / 0 0 0 0
GAGE OK 63 30 53 24 / 0 0 0 0
PONCA CITY OK 66 34 58 32 / 0 0 0 10
DURANT OK 68 48 68 40 / 0 0 0 0
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...RED FLAG WARNING UNTIL 5 PM CST THIS AFTERNOON FOR TXZ084>090.
&&
$$
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
306 PM CST SAT DEC 15 2012
.SHORT TERM...
TEMPERATURES THIS AFTERNOON RANGE FROM THE LOWER 60S ACROSS THE
NORTHERN BIG COUNTRY TO THE MID 70S ACROSS THE NORTHWEST HILL
COUNTRY. THE GUSTY WEST WINDS THAT WERE FORECAST FOR TODAY NEVER
REALLY MATERIALIZED DUE...IN LARGER PART...TO THE THICK MID/HIGH
CLOUD COVER THAT MOVED IN FROM THE SOUTH AND WEST. THIS IS IN
RESPONSE TO A 150 KT H25 SUBTROPICAL JET STREAK ORIENTED FROM
NORTHWEST MEXICO INTO SOUTHWEST OK. THIS JET AXIS IS PROGGED TO
SLIDE JUST TO OUR SOUTHEAST OVER THE NEXT 24 HOURS WHICH WOULD HELP
ELIMINATE MUCH OF THE HIGH CLOUDS OVER OUR CWA. IN THE MEANTIME...
WE CAN EXPECT MOSTLY CLOUDY SKIES OVERNIGHT WHICH GENERALLY MEANS
WARMER TEMPS THAN THOSE SUGGESTED BY GUIDANCE. I INCREASED MINS
ACROSS THE I-10 CORRIDOR WHERE THE THICKEST CLOUD COVER IS EXPECTED.
OTHERWISE...GUIDANCE LOOKED GOOD WITH LOW 40S. THE RAP WAS
GENERATING LIGHT QPF TONIGHT BUT IT REMAINS AN OUTLIER AND LOOKS
SUSPICIOUS AT BEST.
I EXPECT AT LEAST PARTIAL CLEARING SUNDAY AFTERNOON. THIS SHOULD
ALLOW SOME OF THE STRONGER WINDS ALOFT TO MIX DOWN TO THE SURFACE
AND PROVIDE A FEW HOURS OF GUSTY WEST WINDS. I STILL THINK WIND
SPEEDS WILL REMAIN IN THE 15-20 MPH RANGE ACROSS THE BIG COUNTRY AND
CONCHO VALLEY /LIGHTER ELSEWHERE/ DESPITE TODAY/S HUMBLING EXAMPLE.
THE ENHANCED DOWNSLOPE SHOULD HELP PUSH TEMPS BACK INTO THE UPPER
60S TO LOWER 70S AS H85 TEMPS ARE ONLY PROGGED TO COOL BY AROUND 1C
BY 00Z MONDAY.
JOHNSON
.LONG TERM...
THE EXTENDED FORECAST IS CHARACTERIZED BY GENERALLY ABOVE NORMAL
TEMPERATURES AND LITTLE TO NO CHANCE OF PRECIPITATION. AN UPPER
LEVEL TROUGH WILL MOVE ACROSS THE PLAINS ON MONDAY...WITH THE ONLY
REAL AFFECT ON WEST CENTRAL TEXAS BEING AN INCREASE IN WINDS. EXPECT
WEST NORTHWEST WINDS OF 15 TO 20 MPH...WITH TEMPERATURES RANGING
FROM THE MID 60S TO LOWER 70S. A STEADY WARM UP IS FORECAST ON
TUESDAY AND WEDNESDAY AHEAD OF THE NEXT UPPER LEVEL TROUGH. HIGH
TEMPERATURES WILL BE RUNNING 15 TO 20 DEGREES ABOVE SEASONAL
NORMALS...GENERALLY IN THE LOWER TO MID 70S. THE MAIN WEATHER
CONCERN WILL BE THE POTENTIAL FOR STRONG WINDS ON WEDNESDAY. A
FAIRLY POTENT UPPER LEVEL TROUGH WILL APPROACH THE AREA ON
WEDNESDAY...WITH A 994MB SURFACE LOW DEVELOPING OVER THE TEXAS
PANHANDLE. A TIGHT SURFACE PRESSURE GRADIENT WILL DEVELOP ACROSS THE
REGION...RESULTING IN WEST WINDS OF 20 TO 30 MPH...WITH HIGHER
GUSTS...ACROSS MUCH OF THE BIG COUNTRY AND CONCHO VALLEY. FARTHER
SOUTH WINDS SHOULD REMAIN IN THE 15 TO 25 MPH RANGE.
AS THE AFOREMENTIONED UPPER LEVEL TROUGH SWINGS ACROSS THE
PLAINS...A COLD FRONT WILL QUICKLY MOVE THROUGH THE AREA WEDNESDAY
NIGHT. NORTH WINDS OF 15 TO 20 MPH AND COOLER TEMPERATURES CAN BE
EXPECTED BEHIND THE FRONT. I LOWERED HIGH TEMPERATURES BY A FEW
DEGREES FOR THURSDAY...GENERALLY IN THE MID AND UPPER 50S. A CHILLY
MORNING IS FORECAST FRIDAY. SKIES WILL BE MOSTLY CLEAR...DEWPOINTS
WILL BE IN THE SINGLE DIGITS AND SKIES WILL BECOME LIGHT. THE
CURRENT FORECAST HAS LOW TEMPERATURES RANGING FROM THE MID TO UPPER
20S...AND THESE MAY NEED TO LOWERED SLIGHTLY ON FUTURE SHIFTS. A
SLOW WARM UP WILL ENSUE THROUGH NEXT WEEKEND...WITH NO CHANCE OF
PRECIPITATION.
DANIELS
&&
.PRELIMINARY POINT TEMPS/POPS...
ABILENE 44 69 38 66 36 / 0 0 0 0 0
SAN ANGELO 41 71 37 68 35 / 0 0 0 0 0
JUNCTION 43 74 36 71 31 / 5 0 0 0 0
&&
.SJT WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
JOHNSON/DANIELS
AS STATED WITH THE MIDNIGHT SHIFT FORECAST DISCUSSION...MAIN FOCUS
IS ON THE POSSIBLE STORM SYSTEM TO AFFECT THE AREA DURING MID-WEEK.
THIS STORM SYSTEM ORIGINATES OUT OF THAT DEEP UPPER TROUGH MOVING
INTO THE WESTERN U.S. ON TUESDAY. VERY GOOD MODEL AGREEMENT EXISTS
THAT A STORM SYSTEM WILL DEVELOP...BUT THE TRACK IS VERY FAR FROM
CERTAIN. THE TRACK AND DEPTH...AND THUS THE TIMING AND AMOUNT OF
IMPACT TO OUR FORECAST AREA...IS GOING TO DEPEND ON WHEN THE
NORTHERN AND SOUTHERN PORTIONS OF THE UPPER TROUGH PHASE...
1. PHASE WEST OF OUR LONGITUDE...AS SUGGESTED BY THE 15.12Z GFS...A
WIDESPREAD MODERATE TO HEAVY SNOWFALL WOULD OCCUR. THERE IS ALSO
POTENTIAL THAT A SLIGHTLY FAR WEST PHASE LIKE THE 15.06Z DGEX WOULD
YIELD MOSTLY RAIN.
2. PHASE ALONG OUR LONGITUDE...AS SUGGESTED BY THE 15.00Z/15.12Z
ECMWF AND UKMET...WOULD YIELD A LIGHT TO MODERATE SNOWFALL
AREA-WIDE...WITH THE MOST SNOW OVER THE SOUTHEASTERN
HALF...ESPECIALLY GRANT COUNTY.
3. PHASE EAST OF OUR LONGITUDE...AS SUGGESTED BY THE 15.12Z
CANADIAN...RESULTS IN OUR AREA BEING COMPLETELY DRY.
GFS/ECMWF ENSEMBLES PROVIDE NO HELP IN DETERMINING WHICH OF THE
ABOVE SCENARIOS ARE MORE LIKELY TO OCCUR. IN ADDITION...IT MAY BE A
FEW DAYS BEFORE MODELS SETTLE DOWN ON ONE SOLUTION. AS SUCH...WILL
FOLLOW A CONSENSUS APPROACH WHICH LEANS MORE TOWARDS THE SECOND
IDEA. LOOKS LIKE THE BULK OF THE PRECIPITATION...ASSUMING IT
OCCURS...WOULD HAPPEN BETWEEN WEDNESDAY NIGHT AND THURSDAY BEFORE
THE SYSTEM SHIFTS OFF TO THE NORTHEAST.
BEYOND THURSDAY...THERE ARE STRONG INDICATIONS OF RIDGING BUILDING
UP ACROSS THE WESTERN U.S. AND HEADING EASTWARD. THE QUESTION IS
WHEN DOES IT MOVE INTO OUR AREA...WHICH DEPENDS A LOT ON THE
MID-WEEK SYSTEM WITH REGARDS TO HOW FAST IT EXITS. IT SEEMS LIKE
MAYBE FRIDAY NIGHT OR SATURDAY THE RIDGE WOULD BUILD IN...BUT THERE
IS A LOT OF UNCERTAINTY OUT THERE. FOR NOW STUCK WITH A CONSENSUS
APPROACH WHICH YIELDS DRY AND COLDER CONDITIONS FOR FRIDAY INTO
SATURDAY. TEMPERATURES LOOK NEAR OR SLIGHTLY BELOW NORMAL AS SOME
CANADIAN AIR TRIES TO DIVE SOUTH BEHIND THE MID-WEEK SYSTEM.
&&
.AVIATION...THROUGH 18Z SUNDAY
1126 AM CST SAT DEC 15 2012
MAIN SHIELD OF RAIN HAS MOVED NORTH AND EAST OF THE KRST/KLSE TAF
SITES AS LOW PRESSURE WAS MOVING INTO WESTERN IA. LOOK FOR IFR/LIFR
CONDITIONS TO PREVAIL THIS AFTERNOON THROUGH THE OVERNIGHT HOURS
AS THE LOW MOVES OVERHEAD...AND EVENTUALLY INTO NORTHEAST WI
SUNDAY MORNING. LOOKING FOR SOME PATCHY DRIZZLE AND SCATTERED LIGHT
SHOWERS FROM TIME TO TIME AND THEN BACK OVER TO A MORE STEADY-
STATE LIGHT RAIN THIS EVENING AS PRECIPITATION SHIELD ON THE
NORTHWEST SIDE OF THE LOW MOVES IN OVER THE AREA. AT KRST...PLAN
ON THE LIGHT RAIN TO TRANSITION TO LIGHT SNOW BY 06Z...WITH THE
LIGHT SNOW CONTINUING THROUGH ABOUT 15Z...THEN ENDING. AT
KLSE...PLAN ON THE LIGHT RAIN TO ARRIVE IN AROUND 03Z...WITH A
RAIN/SNOW MIX BY 12Z. DUE TO THE RELATIVELY WARM GROUND AND LIGHT
SNOW INTENSITY...LITTLE OR NO ACCUMULATIONS ARE EXPECTED.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
229 PM CST SAT DEC 15 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...DAS