Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/17/12
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 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 TALLAHASSEE FL
945 PM EST Sun Dec 16 2012
...A few strong to severe thunderstorms will be possible Monday...
.NEAR TERM [through Tonight]...
Updated at: 945 pm EST
An area of rain, with some embedded isolated thunderstorms, is still
ongoing from just north of Lake Pontchartrain into north Georgia and
the western Carolinas. The area of rain is situated north of an
ill-defined low-level convergence zone, most likely a composite of
existing outflow boundaries and a weak pressure trough. Thus, most
of the precipitation can generally be considered "post-frontal",
likely being maintained by broad isentropic ascent over a shallow,
cool, near-surface air mass. Model guidance shows very little
movement in the aforementioned convergence zone overnight, with the
area of low-level ascent remaining fairly stationary to the north
and west of our forecast area. The RUC also focuses the best 850mb
moisture transport well west of our area. Thus, the PoPs were kept
highest in the northwest part of our area, with a dry forecast for
southeastern areas (FL Big Bend). Any rain showers east of a PAM-FZG
line should be relatively brief and light - associated with weak
low-level WAA across much of the area.
A strongly forced line of showers (very little to no lightning with
the convection) has been slowly moving southeast over southern
Alabama, and by 0230z was approaching the NW corner of our area.
Several observation sites have observed wind gusts of 30-40 knots,
and this may continue for another couple hours over the far western
portion of our area.
&&
.SHORT TERM [Monday Through Wednesday]...
The progressive longwave trough will continue across Ern states and
amplify further on Monday as a series of impulses/vort max moving
NEWD across OH Valley and SE states with its attendant height
falls.this will develop cyclogenesis early with low lifting NEWD
across OH Valley then PA and into NE states with trailing cold front
initially moving slowly then racing across NE Gulf region during the
aftn and eve as a series of shortwaves race NEWD over Ern Conus.
The PoP will increase Monday to about 70% at Dothan & Albany, 60% at
Tallahassee, and only 40% at Cross City. Total STP not impressive
less than one inch.
The Storm Prediction Center has outlooked AL/GA portions of our
forecast area in a "Slight Risk" (15% probability of a severe storm
within 25 miles of a point, 5% for the rest of our area). Strong mid
tropospheric winds of 60-70 KT and a marginally unstable airmass
(SBCAPE around 500 J/KG) and increasing dew points in the
pre-frontal warm sector favor at least some storm organization.
However, models, especially NAM and ECMWF suggest a gradual decrease
in coverage and intensity of convective band ahead of cold front as
it moves Ewd and the stronger forcing moves towards OH Valley.
Amount of cloud cover could be a determinative factor in instability.
The lack of phasing among the multiple short waves creating a
marginal thermodynamic environment that seems to be preventing this
setup from being a more significant event for our area, as the main
500 mb short wave will be up in the Ohio Valley as it goes
negatively tilted Monday afternoon. Additionally, the forecast 850
mb jet is not forecast to be that impressive for this time of year
(only 40-45 KT), and its core will be just north of our forecast
area. The fairly unidirectional, deep southwest wind field and
unimpressive 0-1 km shear magnitudes suggest that our main severe
threat will be isolated damaging straight line wind gusts in
isolated bowing segments along the convective bands, similar to what
we observed last week with the frontal system just to our north. The
tornado threat appears low, and would be limited to brief,
relatively weak "spin-ups" at the ends of stronger bowing segments.
Beginning Mon night, flow aloft quickly becomes zonal as trough
exits into Atlc. In wake of front, surface high builds into
the central gulf on Tues then moves rapidly Ewd Tues night to
reach coast on Wed ahead of next system. Rain chances will diminish
Monday night (20-30%) as the cold front exits. Despite the frontal
passage, temperatures will remain warm through the period, with
lows in the 50s and 60s, and highs in the 70s ahead of next
frontal event.
&&
.LONG TERM [Wednesday Night through Saturday]...
Model guidance continues to have difficulty resolving various long
term forecast issues during the latter portion of the period as
would be expected in such a fast moving pattern across the CONUS.
The period begins with high pressure across the region quickly
sliding eastward and a strong frontal system approaching Wednesday
night. The models are actually in decent agreement here with respect
to timing. It looks like another cold front will surge through the
region on Thursday bringing a good chance for showers and
thunderstorms. Kinematic fields are strong out ahead of the system
but instability will once again be in doubt given the limited period
of return flow ahead of the system. The 16/00z GFS and Euro do
generate some non-zero areas of surface-based instability ahead of
the frontal boundary so the severe weather potential - while still
uncertain - cannot be ruled out yet.
Beyond Thursday, the forecast continues to be highly variable. While
cooler and drier air will move in behind the front, how cold it gets
and for how long continues to change with each model cycle. This
batch of guidance keeps the bulk of the cold air wrapped up to the
north closer to the core of the mid level trough across the Eastern
Seaboard and with the fast moving pattern, shifts a ridge across the
central CONUS eastward by Saturday, resulting in a quick moderating
trend to temperatures. Given the current pattern and the lack of any
strong signals favoring a significant cold intrusion into the south,
will trend the forecast warmer at the end of the long term period.
Needless to say beyond Thursday, the long term forecast is much
lower confidence than usual given all the run to run model
variability.
&&
.AVIATION [through 00z Tuesday]...
Updated at: 945 pm EST
Multi-layered cloud deck in place across the region this evening.
Expect CIGS to lower through the night (reaching IFR at most
terminals) with showers moving into the western terminals. Clouds,
rain, and winds should limit fog potential. Conditions will slowly
improve over the west by Monday afternoon. However, Alt. Min.
criteria will continue to be met over ern terminals through 00z.
&&
.MARINE...
Winds will veer and gradually increase somewhat into tonight ahead
of an approaching cold front. Expect sea fog to develop nearshore
especially ern most waters. All of the NWP guidance has backed off
a bit on their wind speed forecasts near and behind the cold
front, and headline conditions appear unlikely Monday night thru
Wednesday. In the wake of the front, winds and seas will rapidly
increase to SCEC levels Wed night into Thurs then to advisory
levels Thurs into Fri.
&&
.FIRE WEATHER...
Conditions will remain too moist for fire weather concerns through
mid week with a good chance of wetting rains across the area.
&&
.HYDROLOGY...
Area rivers continue well below action stage, and this will likely
continue this week with storm total QPF values being mostly under an
inch with Monday`s cold front.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 63 74 54 73 40 / 30 60 30 10 10
Panama City 64 72 60 71 50 / 40 60 20 0 10
Dothan 62 72 52 69 42 / 50 70 20 0 10
Albany 61 73 54 69 40 / 50 70 20 0 10
Valdosta 61 74 57 71 41 / 30 60 30 10 10
Cross City 60 75 60 73 40 / 10 40 30 10 10
Apalachicola 65 73 61 71 52 / 20 50 30 10 10
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
FL...None.
GA...None.
AL...None.
GM...None.
&&
$$
NEAR TERM...Lamers
SHORT TERM...Block
LONG TERM...Godsey
AVIATION...Camp
MARINE...Block/Fournier
FIRE WEATHER...Evans
HYDROLOGY...Block/Fournier
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...UPDATED
NWS DES MOINES IA
855 PM CST SUN DEC 16 2012
.UPDATE...
HAVE UPDATED THE FORECAST TO REMOVE PRECIPITATION WORDING AS MUCH OF
THE LIGHT RAIN/SNOW HAS DISSIPATED ACROSS CENTRAL IOWA. ALSO HAVE
INCREASED AREA OF PATCHY FOG MENTION TO INCLUDE NORTHWESTERN CWA
THIS EVENING...AND UPGRADED ALL FOG MENTION LATE TONIGHT TO AREAS OF
FOG VERSUS THE PATCHY IN THE PREVIOUS GRIDS. BUFKIT SOUNDINGS
SHOWING DECENT SATURATION NEAR THE SURFACE LATE TONIGHT WITH LOW
STRATUS ACROSS NORTHWESTERN IOWA/SRN MN STILL EXPECTED TO CONTINUE
PROGRESSING SOUTH SOUTHEASTWARD OVERNIGHT. AREAS BENEATH THE LOWER
CLOUDS ALREADY DROPPING INTO THE 1/2 MILE TO 2 MILE RANGE...SO
EXPECT AREAS ESPECIALLY ACROSS NORTHERN IOWA TO DROP OFF LATE
TONIGHT AS TEMPERATURES CONTINUE TO COOL OFF A BIT MORE AND
DEWPOINTS REMAIN IN THE MID TO UPPER TEENS.
.SHORT TERM /TONIGHT/...
CHALLENGING FORECAST ESPECIALLY FROM A FOG AND LOW CLOUDS
PERSPECTIVE. FOG AND LOW CLOUDS HAVE BEEN STUBBORN IN LIFTING TODAY
ESPECIALLY ACROSS THE SOUTHERN...CENTRAL AND EASTERN CWA. AND IN THE
NORTHWESTERN CWA WHERE THE FOG AND LOW CLOUDS DID LIFT...ANOTHER
AREA OF LOW CLOUDS HAS BEEN MOVING SOUTHEAST FROM SOUTH DAKOTA AND
MINNESOTA.
HAVE TAKEN A SOMEWHAT PESSIMISTIC APPROACH TO THE LOW CLOUDS AND FOG
FOR TONIGHT. ALTHOUGH BUFKIT NAM SOUNDINGS ARE OPTIMISTIC...THE
BUFKIT RAP SOUNDINGS ARE QUITE PESSIMISTIC. THE FORECAST TENDS TO
SPLIT THE DIFFERENCE WITH A LEAN TOWARD THE LOW CLOUDS AND FOG BEING
STUBBORN. LOW LEVEL MOISTURE IS EXPECTED TO REMAIN PLENTIFUL
OVERNIGHT ESPECIALLY IN THOSE AREAS THAT STILL HAVE LOW CLOUDS AND
FOG. WITH WIND SPEEDS DECREASING OVERNIGHT...MIXING WILL DIMINISH
AND THE FOG IS EXPECTED TO COME BACK. THUS HAVE GONE WITH PATCHY FOG
WORDING IN MANY AREAS FOR TONIGHT/S FCST GRIDS. IN THE NORTHWESTERN
CWA...HAVE BROUGHT THE CLOUDS BACK IN ALONG WITH THE POSSIBILITY OF
PATCHY FOG THERE AS WELL. THE LOWEST VISIBILITIES IN THE FOG ARE
EXPECTED TO BE IN THE NORTHEASTERN CWA.
ON A DIFFERENT NOTE...SOME WEAK FRONTOGENETICAL FORCING HAS LED TO
AN AREA OF ECHOES ON THE RADAR MAINLY ACROSS THE WESTERN CWA TODAY.
OVER TIME THE ECHOES HAVE SPREAD EASTWARD...INDICATING THAT THE
FORCING IS TRANSLATING EASTWARD...WHICH IS SUPPORTED BY MODEL CROSS
SECTIONS. SINCE THE PRECIP IS NOT EXPECTED TO REACH THE GROUND
MUCH...IF AT ALL...HAVE GONE ONLY WITH SLIGHT CHANCE POPS ACROSS THE
SOUTHERN CWA INTO THIS EVE. THERE IS A DRY ENOUGH LAYER BETWEEN THE
LAYER OF FORCING AND THE LOWER LEVEL MOISTURE THAT THE PRECIP IS NOT
EXPECTED TO MAKE IT THROUGH THAT DRIER LAYER.
.LONG TERM /MONDAY THROUGH SUNDAY/...
A PAIR OF SUCCESSIVE 500 MB SHORTWAVES WILL MOVE ACROSS NORTHERN
IOWA...THE FIRST ON MONDAY AND THE SECOND ON TUESDAY MORNING. AT THE
SURFACE A HIGH PRESSURE RIDGE WILL CROSS THE AREA ON MONDAY...WITH
THE MID-LEVEL SHORTWAVE GENERATING CLOUDS BUT FORECAST SOUNDINGS
INDICATING TOO MUCH DRY AIR IN THE LOWER LEVELS TO RESULT IN
PRECIPITATION. ON MONDAY NIGHT HOWEVER THE RIDGE WILL MOVE OFF TO
THE EAST...AND A SURFACE LOW WILL DEVELOP AROUND THE BLACK HILLS
AHEAD OF THE APPROACHING SECOND WAVE AND MOVE QUICKLY EASTWARD
TOWARD IOWA. THIS WILL CAUSE SURFACE WINDS TO COME AROUND QUICKLY TO
SOUTH BY EARLY TUESDAY MORNING WITH AN INCREASE IN ATMOSPHERIC
MOISTURE. AS THE WAVE AND LOW CROSS THE AREA ON TUESDAY MORNING IT
WILL PROVIDE A BRIEF OPPORTUNITY FOR SOME LIGHT SNOW ACROSS OUR FAR
NORTH BEFORE THE SYSTEM CLEARS OUT RAPIDLY TO THE EAST. AT THIS TIME
WILL STICK WITH JUST SLIGHT POPS ROUGHLY NORTH OF HIGHWAY 20 ON
TUESDAY MORNING...AND LITTLE IF ANY ACCUMULATION IS ANTICIPATED.
THE BIGGEST POTENTIAL WEATHER IMPACT OF THE SEVEN DAY FORECAST WILL
COME FROM A LONGWAVE 500 MB TROUGH COMING ASHORE OVER THE PACIFIC
U.S. COAST LATE ON TUESDAY. IT STILL APPEARS THAT THIS TROUGH WILL
NOT BE FULLY PHASED...AND THAT MOST OF THE ENERGY WILL DIG INTO THE
SOUTHERN STREAM WITH A NORTHERN STREAM WAVE TRAILING SLIGHTLY
BEHIND. AS THE OVERALL SYSTEM MOVES EASTWARD TOWARD THE CENTRAL U.S.
AND IOWA THE COMPLICATED EVOLUTION OF THE TWO INTERTWINED WAVES WILL
HAVE DRAMATIC IMPACTS ON THE DETAILS OF THEIR ASSOCIATED SENSIBLE
WEATHER. THE SOUTHERN STREAM WAVE WILL GENERATE A STRONG SURFACE LOW
PRESSURE CENTER OVER THE SOUTHERN HIGH PLAINS ON TUESDAY NIGHT/EARLY
WEDNESDAY...WHICH WILL SUBSEQUENTLY MOVE EAST NORTHEAST ACROSS
MISSOURI AND ILLINOIS...WITH A LARGE SWATH OF SNOW SPREADING ALONG
THE NORTHWESTERN FLANK OF THE TRACK. HOWEVER THE PHASING
ISSUES...COMBINED WITH THE FACT THAT THE ENTIRE SYSTEM IS STILL WELL
OFFSHORE AND NOT BEING SAMPLED BY THE UPPER AIR NETWORK...ARE
WREAKING HAVOC WITH THE FORECAST OF THE STORM TRACK BEING OUTPUT BY
THE VARIOUS PROGNOSTIC MODELS. A SHIFT OF 50 OR 100 MILES ONE WAY OR
ANOTHER WILL MAKE THE DIFFERENCE BETWEEN THE HEAVIER SNOW SWATH
FALLING ACROSS CENTRAL IOWA...SOUTHEASTERN IOWA...OR NORTHEASTERN
MISSOURI. GIVEN THE INHERENT UNCERTAINTY IN THIS SCENARIO AND POOR
CONSISTENCY AMONG THE MODELS HAVE OPTED TO KEEP THE FORECAST VERY
CLOSE TO PREVIOUS ISSUANCES...WITH LIKELY TO CATEGORICAL POPS ACROSS
ABOUT THE SOUTHEASTERN HALF OR TWO THIRDS OF THE CWA. IT IS STILL
TOO EARLY TO MAKE ANY FORECAST OF SNOWFALL AMOUNTS...BUT SEVERAL
INCHES OF SNOWFALL ARE LIKELY TO THE NORTHWEST OF THE LOW AND
PROBABLY SOMEWHERE IN THE SOUTHEASTERN HALF OF OUR AREA. THIS WILL
BE CLOSELY MONITORED OVER THE NEXT SEVERAL DAYS.
THE MIDWEEK SYSTEM WILL CLEAR OUT QUICKLY LATE THURSDAY AND THURSDAY
NIGHT...AFTER WHICH QUIET AND DRY WEST NORTHWESTERLY 500 MB FLOW
WILL BE ESTABLISHED. THIS WILL LEAD TO COOLER WEATHER...ESPECIALLY
IF A SNOW PACK IS IN PLACE AFTER THE WEDNESDAY/THURSDAY STORM...WITH
NO ADDITIONAL PRECIPITATION IN THE FORECAST.
&&
.AVIATION...17/00Z
STRATUS WITH MAINLY IFR TO MVFR CIGS EXPECTED...AND MAY DIP TO LIFR
AT TIMES LATE TONIGHT. ALSO POSSIBILITY OF FOG SETTING BACK IN LATE
TONIGHT HAVE HAVE IFR TO MVFR VSBYS...BUT WOULD NOT BE SURPRISED IF
SOME LIFR VSBYS ALSO HAPPENED AT THE NORTHERN TAF SITES ALTHOUGH
UNCERTAINTY STILL HIGH. SOME LIGHT RAIN/SNOW MOVING SOUTHEASTWARD
THROUGH CENTRAL/SOUTHERN IOWA THIS EVENING INTO LATE TONIGHT. HAVE
INCLUDED AT KDSM AND KOTM...WITH MAJORITY OF PRECIP EXPECTED TO STAY
ALONG AND SOUTH OF INTERSTATE 80.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...ZOGG
LONG TERM...LEE
AVIATION...BEERENDS
UPDATE...BEERENDS
AREA FORECAST DISCUSSION
NWS DES MOINES IA
535 PM CST SUN DEC 16 2012
.SHORT TERM /TONIGHT/...
CHALLENGING FORECAST ESPECIALLY FROM A FOG AND LOW CLOUDS
PERSPECTIVE. FOG AND LOW CLOUDS HAVE BEEN STUBBORN IN LIFTING TODAY
ESPECIALLY ACROSS THE SOUTHERN...CENTRAL AND EASTERN CWA. AND IN THE
NORTHWESTERN CWA WHERE THE FOG AND LOW CLOUDS DID LIFT...ANOTHER
AREA OF LOW CLOUDS HAS BEEN MOVING SOUTHEAST FROM SOUTH DAKOTA AND
MINNESOTA.
HAVE TAKEN A SOMEWHAT PESSIMISTIC APPROACH TO THE LOW CLOUDS AND FOG
FOR TONIGHT. ALTHOUGH BUFKIT NAM SOUNDINGS ARE OPTIMISTIC...THE
BUFKIT RAP SOUNDINGS ARE QUITE PESSIMISTIC. THE FORECAST TENDS TO
SPLIT THE DIFFERENCE WITH A LEAN TOWARD THE LOW CLOUDS AND FOG BEING
STUBBORN. LOW LEVEL MOISTURE IS EXPECTED TO REMAIN PLENTIFUL
OVERNIGHT ESPECIALLY IN THOSE AREAS THAT STILL HAVE LOW CLOUDS AND
FOG. WITH WIND SPEEDS DECREASING OVERNIGHT...MIXING WILL DIMINISH
AND THE FOG IS EXPECTED TO COME BACK. THUS HAVE GONE WITH PATCHY FOG
WORDING IN MANY AREAS FOR TONIGHT/S FCST GRIDS. IN THE NORTHWESTERN
CWA...HAVE BROUGHT THE CLOUDS BACK IN ALONG WITH THE POSSIBILITY OF
PATCHY FOG THERE AS WELL. THE LOWEST VISIBILITIES IN THE FOG ARE
EXPECTED TO BE IN THE NORTHEASTERN CWA.
ON A DIFFERENT NOTE...SOME WEAK FRONTOGENETICAL FORCING HAS LED TO
AN AREA OF ECHOES ON THE RADAR MAINLY ACROSS THE WESTERN CWA TODAY.
OVER TIME THE ECHOES HAVE SPREAD EASTWARD...INDICATING THAT THE
FORCING IS TRANSLATING EASTWARD...WHICH IS SUPPORTED BY MODEL CROSS
SECTIONS. SINCE THE PRECIP IS NOT EXPECTED TO REACH THE GROUND
MUCH...IF AT ALL...HAVE GONE ONLY WITH SLIGHT CHANCE POPS ACROSS THE
SOUTHERN CWA INTO THIS EVE. THERE IS A DRY ENOUGH LAYER BETWEEN THE
LAYER OF FORCING AND THE LOWER LEVEL MOISTURE THAT THE PRECIP IS NOT
EXPECTED TO MAKE IT THROUGH THAT DRIER LAYER.
.LONG TERM /MONDAY THROUGH SUNDAY/...
A PAIR OF SUCCESSIVE 500 MB SHORTWAVES WILL MOVE ACROSS NORTHERN
IOWA...THE FIRST ON MONDAY AND THE SECOND ON TUESDAY MORNING. AT THE
SURFACE A HIGH PRESSURE RIDGE WILL CROSS THE AREA ON MONDAY...WITH
THE MID-LEVEL SHORTWAVE GENERATING CLOUDS BUT FORECAST SOUNDINGS
INDICATING TOO MUCH DRY AIR IN THE LOWER LEVELS TO RESULT IN
PRECIPITATION. ON MONDAY NIGHT HOWEVER THE RIDGE WILL MOVE OFF TO
THE EAST...AND A SURFACE LOW WILL DEVELOP AROUND THE BLACK HILLS
AHEAD OF THE APPROACHING SECOND WAVE AND MOVE QUICKLY EASTWARD
TOWARD IOWA. THIS WILL CAUSE SURFACE WINDS TO COME AROUND QUICKLY TO
SOUTH BY EARLY TUESDAY MORNING WITH AN INCREASE IN ATMOSPHERIC
MOISTURE. AS THE WAVE AND LOW CROSS THE AREA ON TUESDAY MORNING IT
WILL PROVIDE A BRIEF OPPORTUNITY FOR SOME LIGHT SNOW ACROSS OUR FAR
NORTH BEFORE THE SYSTEM CLEARS OUT RAPIDLY TO THE EAST. AT THIS TIME
WILL STICK WITH JUST SLIGHT POPS ROUGHLY NORTH OF HIGHWAY 20 ON
TUESDAY MORNING...AND LITTLE IF ANY ACCUMULATION IS ANTICIPATED.
THE BIGGEST POTENTIAL WEATHER IMPACT OF THE SEVEN DAY FORECAST WILL
COME FROM A LONGWAVE 500 MB TROUGH COMING ASHORE OVER THE PACIFIC
U.S. COAST LATE ON TUESDAY. IT STILL APPEARS THAT THIS TROUGH WILL
NOT BE FULLY PHASED...AND THAT MOST OF THE ENERGY WILL DIG INTO THE
SOUTHERN STREAM WITH A NORTHERN STREAM WAVE TRAILING SLIGHTLY
BEHIND. AS THE OVERALL SYSTEM MOVES EASTWARD TOWARD THE CENTRAL U.S.
AND IOWA THE COMPLICATED EVOLUTION OF THE TWO INTERTWINED WAVES WILL
HAVE DRAMATIC IMPACTS ON THE DETAILS OF THEIR ASSOCIATED SENSIBLE
WEATHER. THE SOUTHERN STREAM WAVE WILL GENERATE A STRONG SURFACE LOW
PRESSURE CENTER OVER THE SOUTHERN HIGH PLAINS ON TUESDAY NIGHT/EARLY
WEDNESDAY...WHICH WILL SUBSEQUENTLY MOVE EAST NORTHEAST ACROSS
MISSOURI AND ILLINOIS...WITH A LARGE SWATH OF SNOW SPREADING ALONG
THE NORTHWESTERN FLANK OF THE TRACK. HOWEVER THE PHASING
ISSUES...COMBINED WITH THE FACT THAT THE ENTIRE SYSTEM IS STILL WELL
OFFSHORE AND NOT BEING SAMPLED BY THE UPPER AIR NETWORK...ARE
WREAKING HAVOC WITH THE FORECAST OF THE STORM TRACK BEING OUTPUT BY
THE VARIOUS PROGNOSTIC MODELS. A SHIFT OF 50 OR 100 MILES ONE WAY OR
ANOTHER WILL MAKE THE DIFFERENCE BETWEEN THE HEAVIER SNOW SWATH
FALLING ACROSS CENTRAL IOWA...SOUTHEASTERN IOWA...OR NORTHEASTERN
MISSOURI. GIVEN THE INHERENT UNCERTAINTY IN THIS SCENARIO AND POOR
CONSISTENCY AMONG THE MODELS HAVE OPTED TO KEEP THE FORECAST VERY
CLOSE TO PREVIOUS ISSUANCES...WITH LIKELY TO CATEGORICAL POPS ACROSS
ABOUT THE SOUTHEASTERN HALF OR TWO THIRDS OF THE CWA. IT IS STILL
TOO EARLY TO MAKE ANY FORECAST OF SNOWFALL AMOUNTS...BUT SEVERAL
INCHES OF SNOWFALL ARE LIKELY TO THE NORTHWEST OF THE LOW AND
PROBABLY SOMEWHERE IN THE SOUTHEASTERN HALF OF OUR AREA. THIS WILL
BE CLOSELY MONITORED OVER THE NEXT SEVERAL DAYS.
THE MIDWEEK SYSTEM WILL CLEAR OUT QUICKLY LATE THURSDAY AND THURSDAY
NIGHT...AFTER WHICH QUIET AND DRY WEST NORTHWESTERLY 500 MB FLOW
WILL BE ESTABLISHED. THIS WILL LEAD TO COOLER WEATHER...ESPECIALLY
IF A SNOW PACK IS IN PLACE AFTER THE WEDNESDAY/THURSDAY STORM...WITH
NO ADDITIONAL PRECIPITATION IN THE FORECAST.
&&
.AVIATION...17/00Z
STRATUS WITH MAINLY IFR TO MVFR CIGS EXPECTED...AND MAY DIP TO LIFR
AT TIMES LATE TONIGHT. ALSO POSSIBILITY OF FOG SETTING BACK IN LATE
TONIGHT HAVE HAVE IFR TO MVFR VSBYS...BUT WOULD NOT BE SURPRISED IF
SOME LIFR VSBYS ALSO HAPPENED AT THE NORTHERN TAF SITES ALTHOUGH
UNCERTAINTY STILL HIGH. SOME LIGHT RAIN/SNOW MOVING SOUTHEASTWARD
THROUGH CENTRAL/SOUTHERN IOWA THIS EVENING INTO LATE TONIGHT. HAVE
INCLUDED AT KDSM AND KOTM...WITH MAJORITY OF PRECIP EXPECTED TO STAY
ALONG AND SOUTH OF INTERSTATE 80.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...ZOGG
LONG TERM...LEE
AVIATION...BEERENDS
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 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
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
1001 PM EST SUN DEC 16 2012
.SYNOPSIS...
LOW PRESSURE LIFTING NORTHEASTWARD ACROSS THE GREAT LAKES WILL
PROVIDE MILD AND CLOUDY CONDITIONS FOR THE UPPER OHIO VALLEY WITH
A FEW LIGHT SHOWERS INTO MONDAY MORNING. A LOW PRESSURE SYSTEM
WILL DEVELOP OVERNIGHT NEAR ARKANSAS THEN MOVE NORTHEASTWARD WITH
MORE NUMEROUS SHOWERS LATER MONDAY INTO MIDDAY TUESDAY. A STRONG
COLD FRONT LATE THURSDAY WILL BRING NOTICEABLY COLDER TEMPERATURES
FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
03Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO
INCREASE INITIAL OVERNIGHT POPS NORTHWEST OF PITTSBURGH. LITTLE
CHANGE TO FORECAST AND FOLLOWING DISCUSSION OTHERWISE.
THE LATEST RAP UPPER LEVEL ANALYSIS INDICATES A 300MB JET
EXTENDING FROM TEXAS INTO THE OHIO VALLEY. THIS JET IS CHANNELING
AN AIR MASS INTO THE REGION THAT IS ACTUALLY OF PACIFIC-
ORIGIN...NEAR THE BAJA CALIFORNIA REGION. AT THE MID-LEVELS...A
BROAD 500MB TROUGH EXTENDS ACROSS THE CENTRAL US...LEAVING THE
UPPER OHIO VALLEY IN A SOUTHWESTERLY FLOW. AT THE SURFACE...A
1002MB LOW IS ACROSS LAKE SUPERIOR. A WARM FRONT EXTENDS SOUTHEAST OF THIS
FEATURE AND IS CURRENTLY IN THE VICINITY OF DU BOIS. THUS...WITH A
MOIST...SOUTHWESTERLY FLOW ALOFT IN PLACE AND A WARM FRONT
SHIFTING NORTH OF THE AREA...TEMPS ARE UNSEASONABLY WARM THIS
EVENING WITH WEAK VORT ENERGY AND SUFFICIENT MOISTURE ALLOWING FOR
A SHOWERS...PRIMARILY FOCUSED ALONG A NARROW CORRIDOR NORTHWEST
OF PITTSBURGH.
TONIGHT...THE WARM FRONT WILL BE SLOW TO SHIFT NORTHEAST OF THE
AREA TONIGHT WITH THE AREA IN WAA. THUS...TEMPS WILL BE FAIRLY
STEADY OVERNIGHT IN THE LOWER TO MID 50S ACROSS THE LOWLANDS AND
IN THE MID 40S ACROSS THE EASTERN RIDGES AND NORTHEAST OF A
DU BOIS-FRANKLIN LINE. CONSIDERED GOING DRY WITH THE FORECAST
INITIALLY TONIGHT FOR PORTIONS OF THE AREA...HOWEVER THE HRRR/4KM
NAM SUPPORT VORT ENERGY ALLOWING FOR SHOWERS TO REDEVELOP.
THUS...WENT SCHC ACROSS MOST OF THE AREA AND THEN INCREASED POPS
TO CHC SOUTH OF THE I-70 CORRIDOR BY DAWN ON MONDAY. THE INCREASE
TO CHC ACROSS THE SOUTH IS WITH THE SUPPORT OF HIRES MODELS
RESOLVING A NARROW AXIS OF SHOWERS PUSHING INTO THIS AREA.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/...
RECENT SREF MODEL OUTPUT...WITH DETAILS FROM NAM GFS AND WRF-
NMM...SHOW SHOWERS...ASSOCIATED WITH LOW PRESSURE CENTER TRACKING
NORTHEASTWARD ALONG THE APPALACHIAN MOUNTAINS...SPREADING SOUTH TO
NORTH ACROSS THE UPPER OHIO VALLEY MONDAY AND MONDAY NIGHT.
SHOWERS WILL EXIT EAST AS THE LOW PRESSURE CENTER EXITS PAST NEW
ENGLAND TUESDAY AFTERNOON.
ENSUING COLD POOL IS NOT THAT COLD OR DEEP...SO INSTABILITY
FOR SHOWERS WILL LIKEWISE BE WEAK. SO IT APPEARS LIKELY THAT MOST
POST SYSTEM SHOWERS WILL HAVE ENDED FOR MOST LOCATIONS BEFORE ANY
CHANGE OVER TO LIGHT OR WET SNOW OCCURS LATE TUESDAY AFTERNOON.
CONSENSUS OF GFS AND NAM MOS PLUS SREF MEAN VALUES SHOW TEMPERATURES
COOLING WITH THE SHOWERS AND LOW PRESSURE PASSAGE MONDAY NIGHT AND
TUESDAY...BUT STILL BE GENERALLY UP TO 10 DEGREES WARMER THAN NORMAL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
WEAK HIGH PRESSURE RIDGE WILL BUILD IN TUESDAY NIGHT BEHIND
DEPARTING LOW PRESSURE. THINK THAT SHOWERS WILL DISSIPATE QUICKLY
TUESDAY EVENING AS INVERSION HEIGHTS FALL RAPIDLY. SKIES WILL REMAIN
AT LEAST PARTLY CLOUDY THROUGH MUCH OF TUESDAY NIGHT AND
WEDNESDAY...ALTHOUGH FLOW WILL INCLUDE A SOUTHERLY COMPONENT AND NOT
ALLOW FOR LAKE EFFECT.
MODELS ARE THEN IN GENERAL AGREEMENT ABOUT LOW PRESSURE MOVING
NORTHEAST ACROSS THE CENTRAL PLAINS INTO ONTARIO BY FRIDAY MORNING.
SLIGHTLY INCREASED THE LIKELY POPS THAT WERE ALREADY IN THE FORECAST
WITH SOLID CONSENSUS FROM DETERMINISTIC/ENSEMBLE MODELS.
TEMPERATURES WILL SURGE INTO THE LOWER 50S AHEAD OF THE FRONT ON
THURSDAY...WITH A STRONG DROPOFF AS THE FRONT MOVES THROUGH. IN
FACT...HIGHS ON FRIDAY MAY ONLY BE A COUPLE DEGREES HIGHER THAN
THURSDAY NIGHT LOWS. ALL PRECIPITATION SHOULD CHANGE OVER FROM RAIN
TO SNOW AFTER MIDNIGHT ON THURSDAY...WITH LAKE EFFECT MACHINE
STARTING UP AT THAT TIME.
ANOTHER CONCERN ON FRIDAY WILL BE WIND GUSTS...WITH LAST 2 GFS RUNS
SHOWING 40-45 KT POTENTIAL WIND GUSTS IN BUFKIT AND CIPS ANALOG
GUIDANCE SUGGESTING THAT ABOUT HALF OF PREVIOUS CLIMATOLOGY EVENTS
HAD WIND GUSTS OVER 40 KTS. 12Z GFS/ECMWF SHOW SOME DISAGREEMENT AS
TO HOW LONG LAKE EFFECT WILL PERSIST...BUT DECIDED TO KEEP AT LEAST
SLIGHT CHANCE POPS UP NORTH THROUGH THE REST OF THE FORECAST.
TEMPERATURES WILL STRUGGLE TO CLIMB ABOVE FREEZING FRIDAY THROUGH
SUNDAY.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
SHOWER ACTIVITY HAS DISSIPATED ACROSS MOST OF THE FORECAST AREA AND
CEILINGS HAVE LIFTED TO GENERAL VFR CONDITIONS. CEILINGS WILL SLOWLY
LOWER TO MVFR DURING THE EARLY MORNING WITH LITTLE RISK OF SHOWERS
OVERNIGHT. AFTER SUNRISE GENERAL VFR CONDITIONS FOR THE LATE MORNING
INTO EARLY AFTERNOON. AS LOW PRESSURE MOVES NORTHEASTWARD WEST OF
THE APPALACHIAN MOUNTAINS MONDAY...SHOWERS AND RESTRICTIONS WILL
SPREAD FROM SOUTH TO NORTH ACROSS THE UPPER OHIO VALLEY MONDAY
AFTERNOON. SURFACE WINDS WILL BE FROM THE SOUTH AND SOUTHEAST AT 5
TO 15 KTS INTO MONDAY.
.OUTLOOK.../MONDAY NIGHT THROUGH FRIDAY/...
IFR RESTRICTIONS CAN OCCUR MONDAY NIGHT INTO TUESDAY MORNING DUE
TO SHOWERS WITH NORTHEASTWARD PASSAGE OF LOW PRESSURE CENTER. SOME
MVFR RESTRICTIONS MAY REMAIN TUESDAY AFTERNOON INTO WEDNESDAY DUE
TO LINGERING POST SYSTEM COLD POOL STRATOCUMULUS. ANOTHER LOW
PRESSURE SYSTEM WILL BRING SHOWERS AND RESTRICTIONS THURSDAY INTO
FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WOODRUM
NEAR TERM...WOODRUM
AVIATION...RSD
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
736 PM EST SUN DEC 16 2012
.SYNOPSIS...
LOW PRESSURE LIFTING NORTHEASTWARD ACROSS THE GREAT LAKES WILL
PROVIDE MILD AND CLOUDY CONDITIONS FOR THE UPPER OHIO VALLEY WITH
ISOLATED LIGHT SHOWERS INTO MONDAY MORNING. A LOW PRESSURE SYSTEM
WILL DEVELOP OVERNIGHT NEAR ARKANSAS THEN MOVE NORTHEASTWARD WITH
MORE NUMEROUS SHOWERS LATER MONDAY INTO MIDDAY TUESDAY. A STRONG
COLD FRONT LATE THURSDAY WILL BRING NOTICEABLY COLDER TEMPERATURES
FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
00Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED IN ORDER
MAKE SLIGHT CHANGES TO POPS AND TEMPS OVERNIGHT.
THE LATEST RAP UPPER LEVEL ANALYSIS INDICATES A 300MB JET
EXTENDING FROM TEXAS INTO THE OHIO VALLEY. THIS JET IS CHANNELING
AN AIR MASS INTO THE REGION THAT IS ACTUALLY OF PACIFIC-
ORIGIN...NEAR THE BAJA CALIFORNIA REGION. AT THE MID-LEVELS...A
BROAD 500MB TROUGH EXTENDS ACROSS THE CENTRAL US...LEAVING THE
UPPER OHIO VALLEY IN A SOUTHWESTERLY FLOW. AT THE SURFACE...A
1000MB LOW IS CENTERED ACROSS THE UPPER PENINSULA OF MICHIGAN. A
WARM FRONT EXTENDS SOUTHEAST OF THIS FEATURE AND IS CURRENTLY
IN THE VICINITY OF DU BOIS. THUS...WITH A MOIST...SOUTHWESTERLY
FLOW ALOFT IN PLACE AND WARM FRONT SHIFTING NORTH OF THE
AREA...TEMPS ARE UNSEASONABLY WARM THIS EVENING WITH WEAK VORT
ENERGY AND SUFFICIENT MOISTURE ALLOWING FOR A FEW ISOLATED
SHOWERS.
TONIGHT...THE WARM FRONT WILL BE SLOW TO SHIFT NORTHEAST OF THE
AREA TONIGHT WITH THE AREA IN WAA. THUS...TEMPS WILL BE FAIRLY
STEADY OVERNIGHT IN THE LOWER TO MID 50S ACROSS THE LOWLANDS AND
IN THE MID 40S ACROSS THE EASTERN RIDGES AND NORTHEAST OF A
DU BOIS-FRANKLIN LINE. CONSIDERED GOING DRY WITH THE FORECAST
INITIALLY TONIGHT...HOWEVER THE HRRR/NAM 4KM SUPPORT VORT ENERGY
ALLOWING FOR SHOWERS TO REDEVELOP. THUS...WENT SCHC ACROSS MOST OF
THE AREA AND THEN INCREASED POPS TO CHC SOUTH OF THE I-70 CORRIDOR
BY DAWN ON MONDAY. THE INCREASE TO CHC ACROSS THE SOUTH IS WITH
THE SUPPORT OF HIRES MODELS RESOLVING A NARROW AXIS OF SHOWERS
PUSHING INTO THIS AREA.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/...
RECENT SREF MODEL OUTPUT...WITH DETAILS FROM NAM GFS AND WRF-
NMM...SHOW SHOWERS...ASSOCIATED WITH LOW PRESSURE CENTER TRACKING
NORTHEASTWARD ALONG THE APPALACHIAN MOUNTAINS...SPREADING SOUTH TO
NORTH ACROSS THE UPPER OHIO VALLEY MONDAY AND MONDAY NIGHT.
SHOWERS WILL EXIT EAST AS THE LOW PRESSURE CENTER EXITS PAST NEW
ENGLAND TUESDAY AFTERNOON.
ENSUING COLD POOL IS NOT THAT COLD OR DEEP...SO INSTABILITY
FOR SHOWERS WILL LIKEWISE BE WEAK. SO IT APPEARS LIKELY THAT MOST
POST SYSTEM SHOWERS WILL HAVE ENDED FOR MOST LOCATIONS BEFORE ANY
CHANGE OVER TO LIGHT OR WET SNOW OCCURS LATE TUESDAY AFTERNOON.
CONSENSUS OF GFS AND NAM MOS PLUS SREF MEAN VALUES SHOW TEMPERATURES
COOLING WITH THE SHOWERS AND LOW PRESSURE PASSAGE MONDAY NIGHT AND
TUESDAY...BUT STILL BE GENERALLY UP TO 10 DEGREES WARMER THAN NORMAL.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
WEAK HIGH PRESSURE RIDGE WILL BUILD IN TUESDAY NIGHT BEHIND
DEPARTING LOW PRESSURE. THINK THAT SHOWERS WILL DISSIPATE QUICKLY
TUESDAY EVENING AS INVERSION HEIGHTS FALL RAPIDLY. SKIES WILL REMAIN
AT LEAST PARTLY CLOUDY THROUGH MUCH OF TUESDAY NIGHT AND
WEDNESDAY...ALTHOUGH FLOW WILL INCLUDE A SOUTHERLY COMPONENT AND NOT
ALLOW FOR LAKE EFFECT.
MODELS ARE THEN IN GENERAL AGREEMENT ABOUT LOW PRESSURE MOVING
NORTHEAST ACROSS THE CENTRAL PLAINS INTO ONTARIO BY FRIDAY MORNING.
SLIGHTLY INCREASED THE LIKELY POPS THAT WERE ALREADY IN THE FORECAST
WITH SOLID CONSENSUS FROM DETERMINISTIC/ENSEMBLE MODELS.
TEMPERATURES WILL SURGE INTO THE LOWER 50S AHEAD OF THE FRONT ON
THURSDAY...WITH A STRONG DROPOFF AS THE FRONT MOVES THROUGH. IN
FACT...HIGHS ON FRIDAY MAY ONLY BE A COUPLE DEGREES HIGHER THAN
THURSDAY NIGHT LOWS. ALL PRECIPITATION SHOULD CHANGE OVER FROM RAIN
TO SNOW AFTER MIDNIGHT ON THURSDAY...WITH LAKE EFFECT MACHINE
STARTING UP AT THAT TIME.
ANOTHER CONCERN ON FRIDAY WILL BE WIND GUSTS...WITH LAST 2 GFS RUNS
SHOWING 40-45 KT POTENTIAL WIND GUSTS IN BUFKIT AND CIPS ANALOG
GUIDANCE SUGGESTING THAT ABOUT HALF OF PREVIOUS CLIMATOLOGY EVENTS
HAD WIND GUSTS OVER 40 KTS. 12Z GFS/ECMWF SHOW SOME DISAGREEMENT AS
TO HOW LONG LAKE EFFECT WILL PERSIST...BUT DECIDED TO KEEP AT LEAST
SLIGHT CHANCE POPS UP NORTH THROUGH THE REST OF THE FORECAST.
TEMPERATURES WILL STRUGGLE TO CLIMB ABOVE FREEZING FRIDAY THROUGH
SUNDAY.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
SHOWER ACTIVITY HAS DISSIPATED ACROSS MOST OF THE FORECAST AREA AND
CEILINGS HAVE LIFTED TO GENERAL VFR CONDITIONS. CEILINGS WILL SLOWLY
LOWER TO MVFR DURING THE EARLY MORNING WITH LITTLE RISK OF SHOWERS
OVERNIGHT. AFTER SUNRISE GENERAL VFR CONDITIONS FOR THE LATE MORNING
INTO EARLY AFTERNOON. AS LOW PRESSURE MOVES NORTHEASTWARD WEST OF
THE APPALACHIAN MOUNTAINS MONDAY...SHOWERS AND RESTRICTIONS WILL
SPREAD FROM SOUTH TO NORTH ACROSS THE UPPER OHIO VALLEY MONDAY
AFTERNOON. SURFACE WINDS WILL BE FROM THE SOUTH AND SOUTHEAST AT 5
TO 15 KTS INTO MONDAY.
.OUTLOOK.../MONDAY NIGHT THROUGH FRIDAY/...
IFR RESTRICTIONS CAN OCCUR MONDAY NIGHT INTO TUESDAY MORNING DUE
TO SHOWERS WITH NORTHEASTWARD PASSAGE OF LOW PRESSURE CENTER. SOME
MVFR RESTRICTIONS MAY REMAIN TUESDAY AFTERNOON INTO WEDNESDAY DUE
TO LINGERING POST SYSTEM COLD POOL STRATOCUMULUS. ANOTHER LOW
PRESSURE SYSTEM WILL BRING SHOWERS AND RESTRICTIONS THURSDAY INTO
FRIDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
SYNOPSIS...WOODRUM
NEAR TERM...WOODRUM
AVIATION...RSD
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 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
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 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 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 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
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 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...UPDATED
NWS HASTINGS NE
900 PM CST SUN DEC 16 2012
.UPDATE...SNOW FLURRIES HAVE BEEN REPORTED WEST OF OUR CWA AND
EXPECT THESE WILL SLIDE ACROSS OUR FORECAST AREA OVER THE NEXT FEW
HOURS. ANY SNOW FLURRIES OR BRIEF LIGHT SNOW WILL LIKELY END
BEFORE DAWN. IR SATELLITE IMAGERY INDICATES COOLING CLOUD TOPS
THIS EVENING ACROSS SOUTH CENTRAL NEBRASKA AND FORECAST MODELS
SHOW A WEAK VORT MAX PRESSING EAST ACROSS THE REGION.
CONSEQUENTLY...DESPITE THE LACK OF MODEL QPF...BELIEVE THAT FLURRIES
WILL CONTINUE TO BE POSSIBLE WITH THIS UPPER TROUGH AS IT SLIDES
EAST TONIGHT.
&&
.PREV DISCUSSION... /ISSUED 600 PM CST SUN DEC 16 2012/
AVIATION...00Z KGRI TAF. LOW CLOUDS HAVE MOVED JUST OFF TO THE
EAST OF KGRI...BUT QUESTIONS REMAIN AS TO WHETHER OR NOT THESE LOW
CLOUDS WILL SLIDE BACK INTO KGRI DURING THE EARLY MORNING HOURS.
WILL CONTINUE ALONG THE LINE OF THE PREVIOUS FORECAST IN KEEPING
THE PREVAILING CONDITIONS VFR. HOWEVER...HAVE ADDED A TEMPO GROUP
FOR IFR CEILINGS AND SOME VISIBILITY REDUCTIONS FOR THE SEVERAL
HOURS EITHER SIDE OF DAWN GIVEN AT LEAST SOME POSSIBILITY THAT
THESE LOW CLOUDS WILL EXPAND BACK TO THE WEST. ANY LOW CLOUDS WILL
QUICKLY LIFT BY MID MORNING WITH VFR CONDITIONS EXPECTED THROUGH
MOST OF TOMORROW. THE WIND WILL BE LIGHT THROUGHOUT THE TAF VALID
PERIOD AND SOMEWHAT SHIFTY WITH NO STRONG FORCING.
PREV DISCUSSION... /ISSUED 337 PM CST SUN DEC 16 2012/
SHORT TERM...TONIGHT AND TOMORROW.
UPPER LEVEL SATELLITE DATA HAS SHOW A FEW SMALL DISTURBANCES
SHIFTING ACROSS THE PLAINS TODAY...ONE OF WHICH BROUGHT SOME LIGHT
SNOW TO PORTIONS OF THE CWA THIS MORNING. TRACE AMOUNTS UP NEAR
A HALF OF AN INCH WERE REPORTED...AND BY MIDDAY PRECIPITATION
TRENDS HAD FALLEN BACK TO JUST A FEW SCATTERED FLURRIES IN
NORTHEASTERN PORTIONS OF THE CWA. CLOUD COVER HAS BEEN
ANNOYING...THE NORTHEASTERN HALF OF THE CWA HAS BEEN STUCK UNDER
STUBBORN LOW LEVEL STRATUS...VS THE WESTERN HALF WHICH HAS SEEN
PLENTY OF SUN. SURFACE ANALYSIS SHOWS A RIDGE AXIS EXTENDING
THROUGH THE CENTRAL/EASTERN PORTIONS OF THE REGION...KEEPING WINDS
GENERALLY ON THE LIGHT AND AT TIMES VARIABLE SIDE. THANKS TO THE
CLOUD COVER...EASTERN LOCATIONS HAVE HUNG AROUND THE LOW 30S THIS
AFTERNOON...OUT WEST HAS REACHED INTO THE LOWER 40S.
KEPT THE FORECAST TONIGHT DRY...THOUGH MODELS ARE SHOWING ANOTHER
WEAK DISTURBANCE SWINGING THOUGH THE REGION...POTENTIALLY BRINGING
SOME ADDITIONAL LIGHT PRECIPITATION. AT THIS POINT...SHOULD ANY
PRECIPITATION FALL...IT LOOKS TO REMAIN JUST OFF TO THE
SOUTH/SOUTHWEST OF THE CWA. AT THE SURFACE...A WEAK TROUGH AXIS
GETS PUSHED THROUGH AS THE DISTURBANCE CROSSES...EVENTUALLY
BRINGING A WESTERLY COMPONENT TO THE WINDS. AHEAD OF THAT
SWITCH...CONCERNED ABOUT THE POTENTIAL FOR SOME PATCHY FOG
DEVELOPMENT...AS THE WINDS REMAIN LIGHT/CALM WITH NOT AS MUCH IN
THE WAY OF CLOUD COVER EXPECTED. WITH THE NAM/SREF BOTH SHOWING
REDUCED VISIBILITIES AND THE RAP NOT TOO FAR OUTSIDE THE CWA
BOUNDARY...DECIDED TO INSERT A PATCHY FOG MENTION ACROSS PORTIONS
OF SC NEB.
INTO MONDAY...EXPECTING TO SEE WEAK SHORTWAVE UPPER LEVEL RIDGING
OVER THE REGION...KEEPING CONDITIONS QUIET. SHOULD SEE VARIABLE
SKY COVER THROUGH THE DAY WITH UPPER LEVEL CLOUDS STREAMING IN.
AT THE SURFACE...THE CWA IS COMING UNDER INCREASING INFLUENCE OF
LOW PRESSURE DEVELOPING OVER THE HIGH PLAINS...RESULTING IN WINDS
BECOMING MORE SOUTHERLY WITH TIME. AFTER LOW TEMPERATURES TONIGHT
EXPECTED IN THE TEENS TO LOWER 20S...HIGHS ON MONDAY LOOK TO REACH
INTO THE LOWER 40S TO NEAR 50.
LONG TERM...MONDAY NIGHT THROUGH SUNDAY.
MAIN CHALLENGE REMAINS DETERMINING CHANCES AND TIMING OF SNOW FOR
WEDNESDAY/WEDNESDAY NIGHT.
WE BEGIN THE LONG TERM FORECAST MONDAY NIGHT WITH ZONAL FLOW. THE
FLOW REMAINS QUITE PROGRESSIVE AS A SIGNIFICANT TROUGH DEVELOPS IN
THE WESTERN UNITED STATES BY TUESDAY. AS A RESPONSE TO THIS
DEEPENING TROUGH TO THE WEST...PLENTY OF WARM AIR WILL ARRIVE ON
TUESDAY AND PLACE OUR HIGH TEMPERATURES WELL ABOVE NORMAL BY ABOUT
15 DEGREES OR SO. THIS ABOVE NORMAL WEATHER WILL MOST CERTAINLY
NOT LAST AS THE TROUGH PROGRESSES QUICKLY TO THE EAST AND AN
ASSOCIATED COLD FRONT SWINGS IN FROM THE NORTHWEST VERY LATE
TUESDAY NIGHT INTO WEDNESDAY. A SHARP COOL DOWN WILL ENSUE.
THE TIMELINE FOR THIS NEXT WAVE IS TRENDING TOWARD A SOONER ARRIVAL
AND SOONER EXIT. ISENTROPIC LIFT BEGINS EARLY WEDNESDAY MORNING
BEHIND A QUICKLY MOVING COLD FRONT...WITH THIS FORCING GIVING WAY
TO MID-LEVEL FRONTOGENETIC FORCING LATER IN THE DAY.
ALSO...LARGER SCALE SYNOPTIC FORCING BECOMES STRONGER AS THE DAY
WEARS ON AND IS FORECAST TO BE RESPECTABLE FOR A SHORT
TIME...ADDING ANOTHER LAYER OF FORCING TO AID IN SNOW PRODUCTION.
THE ECMWF INDICATES THAT SYNOPTIC FORCING WILL PEAK NEAR 00Z
THURSDAY. THIS WAVE IS A QUICK HITTER...HOWEVER...WITH MOST IF NOT
ALL FORCING EAST OF THE CWA BY MIDNIGHT WEDNESDAY NIGHT...WHICH
WILL ALSO END ANY SNOW PRODUCTION. WITH THIS WAVE BEING SUCH A
QUICK HITTER...SNOW AMOUNTS ARE STILL ON TRACK FOR UP TO 4 INCHES
OR SO FOR SOMEBODY NEARBY...BUT THIS PROBABLY WOULD NOT BE A
UBIQUITOUS SNOW AMOUNT. IF THIS SYSTEM SLOWS DOWN JUST A
BIT...THIS COULD MEAN MORE SNOW WITH LARGER SNOW AMOUNTS AND
PLENTY OF WIND TO CREATE DRIFTING SNOW POTENTIAL. WIND ALOFT FOR
WEDNESDAY AFTERNOON AND EVENING IS QUITE STRONG AND BLOWING SNOW
WILL BE A POTENTIAL ISSUE. THERE IS ALSO SOME DISCREPANCY AMONG
MODELS WHERE THE TRACK OF THE 700 MB CLOSED LOW WILL BE AS THE NAM
DRAGS THIS LOW ACROSS THE CENTRAL CWA...WHILE THE ECMWF TAKES THE
700 MB LOW ACROSS CENTRAL KANSAS. THE GFS DOES NOT CLOSE THE LOW
OFF...BUT DOES FAVOR A SOLUTION CLOSER TO THE ECMWF. NO QUESTION
ABOUT PRECIPITATION TYPE SO FAR...AS SOUNDINGS INDICATE ALL SNOW
WITH THIS EVENT. WE TEND TO FAVOR A MORE SOUTHERN TRACK WITH THESE
PACIFIC SYSTEMS. ALSO WEDNESDAY MAY BE A TRICKY DAY FOR HOURLY
TEMPERATURES DEPENDING ON THE TIMING OF THE COLD FRONT. WE COULD
REACH HIGHS MORE TOWARD LATE MORNING RATHER THEN IN THE AFTERNOON.
ANYWAY...TEMPERATURES WILL PROBABLY GO ALMOST NOWHERE FROM THE
LOWS ON TUESDAY NIGHT. I CONTINUED TO GO COLDER THAN ALLBLEND FOR
TEMPERATURES FOR WEDNESDAY NIGHT AND BEYOND CONSIDERING POTENTIAL
SNOW COVER.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
600 PM CST SUN DEC 16 2012
.AVIATION...00Z KGRI TAF. LOW CLOUDS HAVE MOVED JUST OFF TO THE
EAST OF KGRI...BUT QUESTIONS REMAIN AS TO WHETHER OR NOT THESE LOW
CLOUDS WILL SLIDE BACK INTO KGRI DURING THE EARLY MORNING HOURS.
WILL CONTINUE ALONG THE LINE OF THE PREVIOUS FORECAST IN KEEPING
THE PREVAILING CONDITIONS VFR. HOWEVER...HAVE ADDED A TEMPO GROUP
FOR IFR CEILINGS AND SOME VISIBILITY REDUCTIONS FOR THE SEVERAL
HOURS EITHER SIDE OF DAWN GIVEN AT LEAST SOME POSSIBILITY THAT
THESE LOW CLOUDS WILL EXPAND BACK TO THE WEST. ANY LOW CLOUDS WILL
QUICKLY LIFT BY MID MORNING WITH VFR CONDITIONS EXPECTED THROUGH
MOST OF TOMORROW. THE WIND WILL BE LIGHT THROUGHOUT THE TAF VALID
PERIOD AND SOMEWHAT SHIFTY WITH NO STRONG FORCING.
&&
.PREV DISCUSSION... /ISSUED 337 PM CST SUN DEC 16 2012/
SHORT TERM...TONIGHT AND TOMORROW.
UPPER LEVEL SATELLITE DATA HAS SHOW A FEW SMALL DISTURBANCES
SHIFTING ACROSS THE PLAINS TODAY...ONE OF WHICH BROUGHT SOME LIGHT
SNOW TO PORTIONS OF THE CWA THIS MORNING. TRACE AMOUNTS UP NEAR
A HALF OF AN INCH WERE REPORTED...AND BY MIDDAY PRECIPITATION
TRENDS HAD FALLEN BACK TO JUST A FEW SCATTERED FLURRIES IN
NORTHEASTERN PORTIONS OF THE CWA. CLOUD COVER HAS BEEN
ANNOYING...THE NORTHEASTERN HALF OF THE CWA HAS BEEN STUCK UNDER
STUBBORN LOW LEVEL STRATUS...VS THE WESTERN HALF WHICH HAS SEEN
PLENTY OF SUN. SURFACE ANALYSIS SHOWS A RIDGE AXIS EXTENDING
THROUGH THE CENTRAL/EASTERN PORTIONS OF THE REGION...KEEPING WINDS
GENERALLY ON THE LIGHT AND AT TIMES VARIABLE SIDE. THANKS TO THE
CLOUD COVER...EASTERN LOCATIONS HAVE HUNG AROUND THE LOW 30S THIS
AFTERNOON...OUT WEST HAS REACHED INTO THE LOWER 40S.
KEPT THE FORECAST TONIGHT DRY...THOUGH MODELS ARE SHOWING ANOTHER
WEAK DISTURBANCE SWINGING THOUGH THE REGION...POTENTIALLY BRINGING
SOME ADDITIONAL LIGHT PRECIPITATION. AT THIS POINT...SHOULD ANY
PRECIPITATION FALL...IT LOOKS TO REMAIN JUST OFF TO THE
SOUTH/SOUTHWEST OF THE CWA. AT THE SURFACE...A WEAK TROUGH AXIS
GETS PUSHED THROUGH AS THE DISTURBANCE CROSSES...EVENTUALLY
BRINGING A WESTERLY COMPONENT TO THE WINDS. AHEAD OF THAT
SWITCH...CONCERNED ABOUT THE POTENTIAL FOR SOME PATCHY FOG
DEVELOPMENT...AS THE WINDS REMAIN LIGHT/CALM WITH NOT AS MUCH IN
THE WAY OF CLOUD COVER EXPECTED. WITH THE NAM/SREF BOTH SHOWING
REDUCED VISIBILITIES AND THE RAP NOT TOO FAR OUTSIDE THE CWA
BOUNDARY...DECIDED TO INSERT A PATCHY FOG MENTION ACROSS PORTIONS
OF SC NEB.
INTO MONDAY...EXPECTING TO SEE WEAK SHORTWAVE UPPER LEVEL RIDGING
OVER THE REGION...KEEPING CONDITIONS QUIET. SHOULD SEE VARIABLE
SKY COVER THROUGH THE DAY WITH UPPER LEVEL CLOUDS STREAMING IN.
AT THE SURFACE...THE CWA IS COMING UNDER INCREASING INFLUENCE OF
LOW PRESSURE DEVELOPING OVER THE HIGH PLAINS...RESULTING IN WINDS
BECOMING MORE SOUTHERLY WITH TIME. AFTER LOW TEMPERATURES TONIGHT
EXPECTED IN THE TEENS TO LOWER 20S...HIGHS ON MONDAY LOOK TO REACH
INTO THE LOWER 40S TO NEAR 50.
LONG TERM...MONDAY NIGHT THROUGH SUNDAY.
MAIN CHALLENGE REMAINS DETERMINING CHANCES AND TIMING OF SNOW FOR
WEDNESDAY/WEDNESDAY NIGHT.
WE BEGIN THE LONG TERM FORECAST MONDAY NIGHT WITH ZONAL FLOW. THE
FLOW REMAINS QUITE PROGRESSIVE AS A SIGNIFICANT TROUGH DEVELOPS IN
THE WESTERN UNITED STATES BY TUESDAY. AS A RESPONSE TO THIS
DEEPENING TROUGH TO THE WEST...PLENTY OF WARM AIR WILL ARRIVE ON
TUESDAY AND PLACE OUR HIGH TEMPERATURES WELL ABOVE NORMAL BY ABOUT
15 DEGREES OR SO. THIS ABOVE NORMAL WEATHER WILL MOST CERTAINLY
NOT LAST AS THE TROUGH PROGRESSES QUICKLY TO THE EAST AND AN
ASSOCIATED COLD FRONT SWINGS IN FROM THE NORTHWEST VERY LATE
TUESDAY NIGHT INTO WEDNESDAY. A SHARP COOL DOWN WILL ENSUE.
THE TIMELINE FOR THIS NEXT WAVE IS TRENDING TOWARD A SOONER ARRIVAL
AND SOONER EXIT. ISENTROPIC LIFT BEGINS EARLY WEDNESDAY MORNING
BEHIND A QUICKLY MOVING COLD FRONT...WITH THIS FORCING GIVING WAY
TO MID-LEVEL FRONTOGENETIC FORCING LATER IN THE DAY.
ALSO...LARGER SCALE SYNOPTIC FORCING BECOMES STRONGER AS THE DAY
WEARS ON AND IS FORECAST TO BE RESPECTABLE FOR A SHORT
TIME...ADDING ANOTHER LAYER OF FORCING TO AID IN SNOW PRODUCTION.
THE ECMWF INDICATES THAT SYNOPTIC FORCING WILL PEAK NEAR 00Z
THURSDAY. THIS WAVE IS A QUICK HITTER...HOWEVER...WITH MOST IF NOT
ALL FORCING EAST OF THE CWA BY MIDNIGHT WEDNESDAY NIGHT...WHICH
WILL ALSO END ANY SNOW PRODUCTION. WITH THIS WAVE BEING SUCH A
QUICK HITTER...SNOW AMOUNTS ARE STILL ON TRACK FOR UP TO 4 INCHES
OR SO FOR SOMEBODY NEARBY...BUT THIS PROBABLY WOULD NOT BE A
UBIQUITOUS SNOW AMOUNT. IF THIS SYSTEM SLOWS DOWN JUST A
BIT...THIS COULD MEAN MORE SNOW WITH LARGER SNOW AMOUNTS AND
PLENTY OF WIND TO CREATE DRIFTING SNOW POTENTIAL. WIND ALOFT FOR
WEDNESDAY AFTERNOON AND EVENING IS QUITE STRONG AND BLOWING SNOW
WILL BE A POTENTIAL ISSUE. THERE IS ALSO SOME DISCREPANCY AMONG
MODELS WHERE THE TRACK OF THE 700 MB CLOSED LOW WILL BE AS THE NAM
DRAGS THIS LOW ACROSS THE CENTRAL CWA...WHILE THE ECMWF TAKES THE
700 MB LOW ACROSS CENTRAL KANSAS. THE GFS DOES NOT CLOSE THE LOW
OFF...BUT DOES FAVOR A SOLUTION CLOSER TO THE ECMWF. NO QUESTION
ABOUT PRECIPITATION TYPE SO FAR...AS SOUNDINGS INDICATE ALL SNOW
WITH THIS EVENT. WE TEND TO FAVOR A MORE SOUTHERN TRACK WITH THESE
PACIFIC SYSTEMS. ALSO WEDNESDAY MAY BE A TRICKY DAY FOR HOURLY
TEMPERATURES DEPENDING ON THE TIMING OF THE COLD FRONT. WE COULD
REACH HIGHS MORE TOWARD LATE MORNING RATHER THEN IN THE AFTERNOON.
ANYWAY...TEMPERATURES WILL PROBABLY GO ALMOST NOWHERE FROM THE
LOWS ON TUESDAY NIGHT. I CONTINUED TO GO COLDER THAN ALLBLEND FOR
TEMPERATURES FOR WEDNESDAY NIGHT AND BEYOND CONSIDERING POTENTIAL
SNOW COVER.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
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 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.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...POWER
AREA FORECAST DISCUSSION
NWS BISMARCK ND
630 AM CST SAT DEC 15 2012
.SHORT TERM...BAND OF MIXED PRECIPITATION EXTENDS FROM CENTRAL
SOUTH DAKOTA...NORTHEAST THROUGH THE FAR SOUTHEAST CORNER OF NORTH
DAKOTA AND INTO MINNESOTA. HRRR STILL SHOWS SOME OF THIS
PRECIPITATION TOUCHING TWO OF MY SOUTHEAST COUNTIES THOUGH RADAR
LOOPS SEEEM TO BE PULLING SLIGHTLY EAST OF THE AREA. TOO CLOSE TO
REMOVE POPS FOR NOW. A FEW LINGERING QUARTER MILE VISIBILITIES FAR
NORTH CENTRAL BUT NOT WIDESPREAD ENOUGH FOR AN ADVISORY.
.AVIATION...
12Z TAFS SHOW A TREND OF DECREASING CLOUDS AND INCREASING
VISIBILITY AS WEAK SURFACE TROUGH PASSAGE TURNS WINDS NORTH AND
WEST. ALL BUT KJMS SHOULD BE VFR BY 18Z.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...HW
AVIATION...HW
AREA FORECAST DISCUSSION
NWS 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 WILMINGTON OH
956 PM EST SUN DEC 16 2012
.SYNOPSIS...
A WEAK COLD FRONTAL BOUNDARY LOCATED SOUTHEAST OF THE I-71
CORRIDOR WILL SEE LOW PRESSURE MOVE TO THE NORTHEAST ALONG IT ON
MONDAY. THIS WILL COMBINE WITH AN EASTWARD MOVING UPPER LEVEL
TROUGH TO INITIATE SHOWERS AND POSSIBLY SOME THUNDERSTORMS. HIGH
PRESSURE WILL BUILD SOUTH OF THE OHIO VALLEY THROUGH THE MIDDLE OF
THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
17.00Z KILN SOUNDING CAME IN WITH MINUSCULE INSTBY...WITH < 100
J/KG MUCAPE BUT A SOMEWHAT DECENT MID-LEVEL LAPSE RATE IN EXCESS
OF 7 C/KM. MID EVENING WATER VAPOR IMAGERY CONTINUES TO DEPICT A
SHORTWAVE MOVING THROUGH IL TOWARD OH BUT SEEMS TO BE SHEARING
OUT/DEAMPLIFYING A BIT. LAST FEW SETS OF RAP DATA HAVE REALLY
BACKED OFF ON DEGREE OF FORCING WITH THIS WAVE AND HAVE DECREASED
LOW LEVEL JET FOCUS INTO THE WEAK FRONTAL BOUNDARY SAGGING
THROUGH WRN OH. THE RESULT OVER THE LAST FEW HOURS...IS A
SMALLER/LIGHTER QPF FIELD IN THE RAP OVER VERSIONS LOOKED AT
THROUGH THE AFTERNOON. EXPERIMENTAL HRRR HAS SEEN SOME
OUTAGES...BUT LAST AVAILABLE RUN /22Z/ STILL SHOWED A RATHER
HEALTHY BATCH OF SHOWERS DEVELOPING TO THE SW OF CVG AND MOVING
ACROSS OUR SRN/SERN AREAS. THE NEW 17.21 SREF PROBS FOR MEASURABLE
PRECIPITATION HAVE DECREASED MARKEDLY AS WELL FROM 17.15Z VALUES.
ALL IN ALL...WILL MAINTAIN CURRENT AXIS OF RAIN CHANCES BEGINNING
IN NEXT COUPLE OF HOURS ACROSS FAR SRN FORECAST AREA...AND PEAKING
IN THE HOURS AFTER MIDNIGHT FROM SOUTH OF CVG EAST/NORTHEAST INTO
SCNTL OH. BUT HAVE DECREASED CHANCES A BIT FROM PREVIOUS
UPDATE. STILL HAVE A LITTLE THUNDER IN THE GRIDS...BUT BASED ON
THE KILN SOUNDING LIGHTNING IS GOING TO BE TOUGH TO COME BY WITH
EQUILIBRIUM LEVEL TEMPS BARELY TO -20C AND SUCH MEAGER INSTBY.
WITH CLEARING OF HIGH CLOUDS IN THE WEST FOR A FEW HOURS THIS
EVENING...THIS ALLOWED A LOCAL TEMP DROP MORE THAN I HAD PREVIOUS
ANTICIPATED AND THUS HAVE DROPPED MIN TEMPS IN THE WESTERN 1/3RD
OF THE FORECAST AREA. A LITTLE FOG COULD FORM IN THIS AREA BUT IT
APPEARS PER SATELLITE IMAGERY THAT LOW CLOUDS ARE QUICKLY
REDEVELOPING IN THE MOIST ADVECTION SPOKE OF PREVIOUSLY. IT
WOULDN/T TAKE LONG FOR DENSE FOG TO FORM IN THIS NARROW CLEAR SLOT
BETWEEN THE LOW CLOUDS LAGGING THE WEAK COLD FRONT...AND THE THICK
CIRRUS MOVING EAST THROUGH THE AREA. WILL MONITOR.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
WEAK SURFACE FORCING WITH THE NEWD MOVING LOW WILL COMBINE WITH
THE UPWARD MOTION AND VORTICITY MAXIMA AHEAD OF THE UPPER LEVEL
TROUGH TO SPARK ACTIVITY LATE TONIGHT AND MORESO TOMORROW.
UNFORTUNATELY THE SHOWERS SHOULD INITIATE ALONG THE MOISTURE
CONVERGENCE AXIS WHICH IS HARD TO PLACE. BEST ESTIMATES RUN ALONG
THE OHIO RIVER SOUTHWEST OF CINCINNATI...THEN JOG NORTHEAST TO
COLUMBUS. THE LOW LEVEL FORCING WITH THE SURFACE TROUGH IS WELL
AHEAD OF THE STRONGER UPPER LEVEL FORCING WITH THE MID LEVEL
SHORTWAVE...WHICH WILL GIVE A PROLONGED POTENTIAL FOR SHOWER
ACTIVITY BUT NOT A CLEAR CUT INDICATION OF THE
HEAVIEST/STRONGEST/MOST LIKELY PLACEMENT OF THE RAIN. BY DAYBREAK
TUESDAY...THE SURFACE LOW IS WELL EAST OF THE REGION AND THE UPPER
LOW IS EXITING OHIO. ANY RAIN WILL HAVE ENDED OVERNIGHT MONDAY.
TEMPERATURES REMAIN UNSEASONABLY WARM BUT ALL OF THE GUIDANCE WERE
PEGGED WITHIN A FEW DEGREES OF EACH OTHER AND NO SIGNIFICANT
CHANGES WERE MADE HERE. CLOUD COVER WILL BE ON THE DECREASE
TUESDAY BUT ASIDE FROM THIS...IT SHOULD BE A RELATIVELY CLOUDY AND
MILD PERIOD...PARTICULARLY FOR MID DECEMBER.
SPC HAS THUNDERSTORMS OVER THE REGION WITH A SLIGHT CHANCE OF
SEVERE NOTED FOR MUCH OF KENTUCKY. WITH THE DISJOINTED NATURE OF
THE SURFACE AND UPPER FORCING...NO CLEAR CUT STRONG VORT
MAXIMA...AND SIGNIFICANT CLOUD COVER EXPECTED...I DID NOT FEEL THE
NECESSARY INGREDIENTS FOR PARTICULARLY STRONG STORMS WERE PRESENT.
THE THUNDER FORECAST I USED TOOK 12Z NAM CAPES OVER 200 AND ADDED
THEM WHERE RAIN CHANCE WAS GREATER THAN 30...YIELDING A NARROW
SWATH SOUTHEAST OF THE I-71 CORRIDOR LATER TONIGHT AND THEN
GENERALLY OVERSPREADING KY EARLY TOMORROW.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
OPERATIONAL MODELS WERE COMING INTO A BETTER AGREEMENT FOR THE NEXT
WEATHER MAKER TO AFFECT THE AREA THURSDAY INTO FRIDAY. HAVE USED A
BLEND OF THE OPERATIONAL 16.12Z GFS AND THE 16.00Z ECMWF.
THE LONG TERM WILL START OUT QUIET ON WEDNESDAY AS MID LEVEL RIDGING
WILL BE IN PLACE ACROSS THE OHIO VALLEY OUT AHEAD OF AFOREMENTIONED
WEATHER SYSTEM DEVELOPING ACROSS THE SRN PLAINS. CLOUDS WILL
INCREASE THROUGH THE DAY...BUT WE SHOULD AT LEAST SEE PARTLY TO
MOSTLY SUNNY SKIES EARLY ON. HIGH TEMPERATURES WILL CONTINUE TO BE
ABOVE NORMAL...RANGING FROM THE LOWER 50S NORTH TO THE UPPER 50S
SOUTH.
FOR THE PERIOD WEDNESDAY NIGHT INTO THURSDAY NIGHT...A DEEPENING MID
LEVEL TROF AND DEEPENING SFC LOW PRESSURE SYSTEM WILL PULL NORTHEAST
FROM THE SRN PLAINS TO THE GREAT LAKES/OHIO VALLEY REGION. THE TRACK
OF THE SFC LOW CONTINUES TO BE NW OF THE REGION...SO ANY MAJOR
WINTER WEATHER WILL STAY WELL TO OUR NW. THE LOW WILL BE ASSOCIATED
WITH A STRONG COLD FRONT. DEEP MOISTURE COMBINED WITH STRONG
SYNOPTIC SCALE FORCING WILL SPREAD SHOWERS INTO THE REGION WEDNESDAY
NIGHT AND WILL CONTINUE INTO THURSDAY. PCPN SHOULD TAPER OFF SOME
BEHIND FRONTAL PASSAGE. TEMPERATURES WILL WARM INTO THE LOWER AND MID
50S ON THURSDAY FOLLOWED BY FALLING TEMPERATURES LATE IN THE DAY
INTO THURSDAY NIGHT. COLD AIR ADVECTION IN THE WAKE OF THE LOW AND
FRONT WILL BRING SOME WRAP AROUND AND LAKE INDUCED SNOW SHOWERS LATE
THURSDAY INTO THURSDAY NIGHT. RIGHT NOW...ANY SNOW ACCUMULATION
SHOULD BE MINOR. WINDY CONDITIONS ARE FORECAST DUE TO A TIGHTENING
PRESSURE GRADIENT AND MOMENTUM TRANSFER IN THE STRONG COLD AIR
ADVECTION BEHIND FRONTAL PASSAGE THURSDAY INTO THURSDAY NIGHT. SO
WILL MENTION THIS POTENTIAL HAZARD IN THE HWO PRODUCT.
FOR FRIDAY INTO FRIDAY NIGHT...UPR LVL TROF WILL HAVE CLOSED OFF TO
OUR NORTH AND NORTHEAST...AND WILL QUICKLY MOVE AWAY FROM OUR
REGION. CLOUDS AND LINGERING SNOW SHOWERS ON FRIDAY WILL TAPER OFF
FROM SW TO NE THROUGH THE DAY...FOLLOWED BY CLEARING SKIES FRIDAY
NIGHT. THE COLDEST TEMPERATURES OF THE WEEK APPEAR TO BE ON FRIDAY
WITH HIGHS STRUGGLING TO WARM INTO THE LOWER AND MID 30S.
FOR SATURDAY INTO SUNDAY...UPR LVL CLOSED LOW IS EXPECTED TO ROTATE
NORTHEASTWARD WHILE OUR REGION STAYS IN A NORTHWEST FLOW ALOFT ALONG
WITH HIGH PRESSURE AT THE SURFACE. DRY WEATHER ALONG WITH NEAR
SEASONAL TEMPERATURES WILL BE FORECAST ATTM.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
CONFIDENCE IN A CLUSTER OF SHOWERS AND A FEW THUNDERSTORMS
AFFECTING THE TAF SITES ALONG I-71 /CVG...LUK...ILN..LCK...CMH/ IS
SLOWLY INCREASING EARLY THIS EVENING BASED ON A REPEATED SIGNAL IN
RECENT HI-RESOLUTION MODEL GUIDANCE. AFT ABOUT 02Z...SHOULD SEE
MARKED INCREASE IN SHRA IN NRN KY MOVING TOWARDS LUK/CVG AND THEN
UP/EAST OF I-71 TOWARD ILN AND LCK/CMH. CHOSE TO HANDLE THIS WITH
A TEMPO OF MVFR CIGS/VSBYS AND VCTS ALONG WITH THE SHRA. THIS
SHOULD BE PROGRESSIVE ACTIVITY AND BE SHIFTING AWAY FROM THE
TERMINALS AFT 07Z OR SO. THEREAFTER...THE WEAK FRONTAL BOUNDARY
MEANDERING SLOWLY ACROSS THE AREA WILL ALLOW WINDS TO DECREASE AS THE
FRONT STALLS/WASHES OUT. CONTINUED WEAK MOISTURE TRANSPORT INTO
THE AREA SHOULD ALLOW CIGS TO DROP INTO MVFR LEVELS AT ALL SITES
WITH SOME MVFR VSBYS RESTRICTIONS TOO.
WAVE OF LOW PRESSURE RIDES THE WASHED OUT FRONTAL ZONE ON MONDAY
WITH A NEW PUSH OF SHOWERS /AND A FEW STORMS/ OVER MOST OF THE TAF
SITES ESPECIALLY IN THE AFTERNOON...THOUGH THE SRN TAF SITES /CVG
AND LUK/ WILL GET STARTED A LITTLE EARLIER. HELD THUNDER OUT OF
THE FORECAST FOR NOW BUT THINK IT WILL NEED TO BE INSERTED AT SOME
POINT FOR CVG/LUK WHEN TIMING OF THE STRONGEST PUSH OF ACTIVITY
BECOMES A LITTLE MORE DEFINED. AS THE WAVE OF LOW PRESSURE
PASSES...LINGERING DEEP MOISUTRE AND COLD ADVECTION WILL MAINTAIN
LOW /MVFR/ CIGS ACROSS THE SITES.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES WILL BE POSSIBLE FROM
MONDAY NIGHT THROUGH TUESDAY. MVFR CONDITIONS ARE AGAIN EXPECTED ON
THURSDAY. STRONG WINDS ARE LIKELY THURSDAY AFTERNOON AND NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...BINAU
SHORT TERM...FRANKS
LONG TERM...HICKMAN
AVIATION...BINAU
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
703 PM EST SUN DEC 16 2012
.SYNOPSIS...
A WEAK COLD FRONTAL BOUNDARY LOCATED SOUTHEAST OF THE I-71
CORRIDOR WILL SEE LOW PRESSURE MOVE TO THE NORTHEAST ALONG IT ON
MONDAY. THIS WILL COMBINE WITH AN EASTWARD MOVING UPPER LEVEL
TROUGH TO INITIATE SHOWERS AND POSSIBLY SOME THUNDERSTORMS. HIGH
PRESSURE WILL BUILD SOUTH OF THE OHIO VALLEY THROUGH THE MIDDLE OF
THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
TOOK A LOOK AT THE LAST THREE RUNS OF 13KM NCEP RAP...3KM ESRL HRRR...THE
16.18Z RUN OF NAM-WRF...AND EXPERIMENTAL SSEO DATA FROM 16.00Z
RUNS AND THERE CONTINUES TO BE A SIGNAL THAT SHOWERS...AND A FEW
STORMS...WILL SOON DEVELOP NEAR THE OHIO RIVER TO OUR SOUTHWEST
AND LIFT INTO THE FORECAST AREA/TRI-STATE REGION BY 9
PM...CONTINUING QUICKLY NORTHEAST ALONG/EAST OF I-71 THROUGH
MIDNIGHT OR A LITTLE AFTER. 16.15Z SREF PROBABILITIES CORROBORATE
THIS IDEA STRONGLY...SO FORECAST WAS SHIFTED A BIT TO INCREASE
RAIN CHANCES IN THIS CORRIDOR AND EMPHASIZE THE AREAS OF NRN
KY/SWRN OH/SERN IND THAT STAND THE GREATEST THREAT OF SEEING THESE
SHOWERS/STORMS.
SPC SWODY1 CONTINUES TO HIGHLIGHT SMALL THREAT FOR A ROBUST
UPDRAFT OR TWO UPON INITIATION TO OUR SW AND THAT SEEMS LEGIT
BASED ON RECENT HRRR AND OTHER CONVECTION ALLOWING GUIDANCE.
MUCAPE IS PALTRY...BUT HAS BEEN SLOWLY INCREASING LATE THIS
AFTN/EVE IN THIS AREA. DON/T SEE AN ORGANIZED SVR THREAT
HERE.
RIGHT NOW MY FORECAST IS PROBABLY A LITTLE TOO BROAD IN SPACE AND
NOT QUANTITATIVELY HIGH ENOUGH IN RAIN CHANCE...BUT ONCE ECHOES
DEVELOP REFINEMENT SHOULD BE ABLE TO BE TIGHTEN THE NRN/SRN
GRADIENTS ON THE EXPECTED CLUSTER OF SHOWERS/STORMS TO MOVE
THROUGH. REST OF FORECAST LOOKS GREAT ATTM.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
WEAK SURFACE FORCING WITH THE NEWD MOVING LOW WILL COMBINE WITH
THE UPWARD MOTION AND VORTICITY MAXIMA AHEAD OF THE UPPER LEVEL
TROUGH TO SPARK ACTIVITY LATE TONIGHT AND MORESO TOMORROW.
UNFORTUNATELY THE SHOWERS SHOULD INITIATE ALONG THE MOISTURE
CONVERGENCE AXIS WHICH IS HARD TO PLACE. BEST ESTIMATES RUN ALONG
THE OHIO RIVER SOUTHWEST OF CINCINNATI...THEN JOG NORTHEAST TO
COLUMBUS. THE LOW LEVEL FORCING WITH THE SURFACE TROUGH IS WELL
AHEAD OF THE STRONGER UPPER LEVEL FORCING WITH THE MID LEVEL
SHORTWAVE...WHICH WILL GIVE A PROLONGED POTENTIAL FOR SHOWER
ACTIVITY BUT NOT A CLEAR CUT INDICATION OF THE
HEAVIEST/STRONGEST/MOST LIKELY PLACEMENT OF THE RAIN. BY DAYBREAK
TUESDAY...THE SURFACE LOW IS WELL EAST OF THE REGION AND THE UPPER
LOW IS EXITING OHIO. ANY RAIN WILL HAVE ENDED OVERNIGHT MONDAY.
TEMPERATURES REMAIN UNSEASONABLY WARM BUT ALL OF THE GUIDANCE WERE
PEGGED WITHIN A FEW DEGREES OF EACH OTHER AND NO SIGNIFICANT
CHANGES WERE MADE HERE. CLOUD COVER WILL BE ON THE DECREASE
TUESDAY BUT ASIDE FROM THIS...IT SHOULD BE A RELATIVELY CLOUDY AND
MILD PERIOD...PARTICULARLY FOR MID DECEMBER.
SPC HAS THUNDERSTORMS OVER THE REGION WITH A SLIGHT CHANCE OF
SEVERE NOTED FOR MUCH OF KENTUCKY. WITH THE DISJOINTED NATURE OF
THE SURFACE AND UPPER FORCING...NO CLEAR CUT STRONG VORT
MAXIMA...AND SIGNIFICANT CLOUD COVER EXPECTED...I DID NOT FEEL THE
NECESSARY INGREDIENTS FOR PARTICULARLY STRONG STORMS WERE PRESENT.
THE THUNDER FORECAST I USED TOOK 12Z NAM CAPES OVER 200 AND ADDED
THEM WHERE RAIN CHANCE WAS GREATER THAN 30...YIELDING A NARROW
SWATH SOUTHEAST OF THE I-71 CORRIDOR LATER TONIGHT AND THEN
GENERALLY OVERSPREADING KY EARLY TOMORROW.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
OPERATIONAL MODELS WERE COMING INTO A BETTER AGREEMENT FOR THE NEXT
WEATHER MAKER TO AFFECT THE AREA THURSDAY INTO FRIDAY. HAVE USED A
BLEND OF THE OPERATIONAL 16.12Z GFS AND THE 16.00Z ECMWF.
THE LONG TERM WILL START OUT QUIET ON WEDNESDAY AS MID LEVEL RIDGING
WILL BE IN PLACE ACROSS THE OHIO VALLEY OUT AHEAD OF AFOREMENTIONED
WEATHER SYSTEM DEVELOPING ACROSS THE SRN PLAINS. CLOUDS WILL
INCREASE THROUGH THE DAY...BUT WE SHOULD AT LEAST SEE PARTLY TO
MOSTLY SUNNY SKIES EARLY ON. HIGH TEMPERATURES WILL CONTINUE TO BE
ABOVE NORMAL...RANGING FROM THE LOWER 50S NORTH TO THE UPPER 50S
SOUTH.
FOR THE PERIOD WEDNESDAY NIGHT INTO THURSDAY NIGHT...A DEEPENING MID
LEVEL TROF AND DEEPENING SFC LOW PRESSURE SYSTEM WILL PULL NORTHEAST
FROM THE SRN PLAINS TO THE GREAT LAKES/OHIO VALLEY REGION. THE TRACK
OF THE SFC LOW CONTINUES TO BE NW OF THE REGION...SO ANY MAJOR
WINTER WEATHER WILL STAY WELL TO OUR NW. THE LOW WILL BE ASSOCIATED
WITH A STRONG COLD FRONT. DEEP MOISTURE COMBINED WITH STRONG
SYNOPTIC SCALE FORCING WILL SPREAD SHOWERS INTO THE REGION WEDNESDAY
NIGHT AND WILL CONTINUE INTO THURSDAY. PCPN SHOULD TAPER OFF SOME
BEHIND FRONTAL PASSAGE. TEMPERATURES WILL WARM INTO THE LOWER AND MID
50S ON THURSDAY FOLLOWED BY FALLING TEMPERATURES LATE IN THE DAY
INTO THURSDAY NIGHT. COLD AIR ADVECTION IN THE WAKE OF THE LOW AND
FRONT WILL BRING SOME WRAP AROUND AND LAKE INDUCED SNOW SHOWERS LATE
THURSDAY INTO THURSDAY NIGHT. RIGHT NOW...ANY SNOW ACCUMULATION
SHOULD BE MINOR. WINDY CONDITIONS ARE FORECAST DUE TO A TIGHTENING
PRESSURE GRADIENT AND MOMENTUM TRANSFER IN THE STRONG COLD AIR
ADVECTION BEHIND FRONTAL PASSAGE THURSDAY INTO THURSDAY NIGHT. SO
WILL MENTION THIS POTENTIAL HAZARD IN THE HWO PRODUCT.
FOR FRIDAY INTO FRIDAY NIGHT...UPR LVL TROF WILL HAVE CLOSED OFF TO
OUR NORTH AND NORTHEAST...AND WILL QUICKLY MOVE AWAY FROM OUR
REGION. CLOUDS AND LINGERING SNOW SHOWERS ON FRIDAY WILL TAPER OFF
FROM SW TO NE THROUGH THE DAY...FOLLOWED BY CLEARING SKIES FRIDAY
NIGHT. THE COLDEST TEMPERATURES OF THE WEEK APPEAR TO BE ON FRIDAY
WITH HIGHS STRUGGLING TO WARM INTO THE LOWER AND MID 30S.
FOR SATURDAY INTO SUNDAY...UPR LVL CLOSED LOW IS EXPECTED TO ROTATE
NORTHEASTWARD WHILE OUR REGION STAYS IN A NORTHWEST FLOW ALOFT ALONG
WITH HIGH PRESSURE AT THE SURFACE. DRY WEATHER ALONG WITH NEAR
SEASONAL TEMPERATURES WILL BE FORECAST ATTM.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
CONFIDENCE IN A CLUSTER OF SHOWERS AND A FEW THUNDERSTORMS
AFFECTING THE TAF SITES ALONG I-71 /CVG...LUK...ILN..LCK...CMH/ IS
SLOWLY INCREASING EARLY THIS EVENING BASED ON A REPEATED SIGNAL IN
RECENT HI-RESOLUTION MODEL GUIDANCE. AFT ABOUT 02Z...SHOULD SEE
MARKED INCREASE IN SHRA IN NRN KY MOVING TOWARDS LUK/CVG AND THEN
UP/EAST OF I-71 TOWARD ILN AND LCK/CMH. CHOSE TO HANDLE THIS WITH
A TEMPO OF MVFR CIGS/VSBYS AND VCTS ALONG WITH THE SHRA. THIS
SHOULD BE PROGRESSIVE ACTIVITY AND BE SHIFTING AWAY FROM THE
TERMINALS AFT 07Z OR SO. THEREAFTER...THE WEAK FRONTAL BOUNDARY
MEANDERING SLOWLY ACROSS THE AREA WILL ALLOW WINDS TO DECREASE AS THE
FRONT STALLS/WASHES OUT. CONTINUED WEAK MOISTURE TRANSPORT INTO
THE AREA SHOULD ALLOW CIGS TO DROP INTO MVFR LEVELS AT ALL SITES
WITH SOME MVFR VSBYS RESTRICTIONS TOO.
WAVE OF LOW PRESSURE RIDES THE WASHED OUT FRONTAL ZONE ON MONDAY
WITH A NEW PUSH OF SHOWERS /AND A FEW STORMS/ OVER MOST OF THE TAF
SITES ESPECIALLY IN THE AFTERNOON...THOUGH THE SRN TAF SITES /CVG
AND LUK/ WILL GET STARTED A LITTLE EARLIER. HELD THUNDER OUT OF
THE FORECAST FOR NOW BUT THINK IT WILL NEED TO BE INSERTED AT SOME
POINT FOR CVG/LUK WHEN TIMING OF THE STRONGEST PUSH OF ACTIVITY
BECOMES A LITTLE MORE DEFINED. AS THE WAVE OF LOW PRESSURE
PASSES...LINGERING DEEP MOISUTRE AND COLD ADVECTION WILL MAINTAIN
LOW /MVFR/ CIGS ACROSS THE SITES.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES WILL BE POSSIBLE FROM
MONDAY NIGHT THROUGH TUESDAY. MVFR CONDITIONS ARE AGAIN EXPECTED ON
THURSDAY. STRONG WINDS ARE LIKELY THURSDAY AFTERNOON AND NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...BINAU
SHORT TERM...FRANKS
LONG TERM...HICKMAN
AVIATION...BINAU
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 PORTLAND OR
716 PM PST SUN DEC 16 2012
.SYNOPSIS...A COLD FRONT THIS EVENING WILL CAUSE WINDS TO SUBSIDE A
BIT ALONG THE COAST AND PRECIPITATION TO TURN MORE SHOWERY.
HOWEVER...A SECOND ROUND OF STRONG WINDS WILL LIKELY IMPACT THE AREA
LATE THIS EVENING INTO THE EARLY MORNING HOURS OF MONDAY. FOR INLAND
SITES...WINDS SHOULD GRADUALLY BUILD THIS EVENING AND PEAK DURING THE
EARLY MORNING HOURS. MEANWHILE...BLIZZARD CONDITIONS WILL OCCUR
ACROSS THE CASCADES PASSES TONIGHT INTO MONDAY. A COLD SHOWERY
WEATHER PATTERN WILL CONTINUE THROUGH TUESDAY WITH SNOW LEVELS
APPROACHING VALLEY FLOORS. THE NEXT STORM SYSTEM WILL MOVE INTO THE
PACIFIC NORTHWEST MIDWEEK.
&&
.SHORT TERM...THE COLD FRONT IS CURRENTLY PUSHING INLAND AND AS A
RESULT...WINDS ARE BEGINNING TO SUBSIDE A TOUCH AT MOST SITES ALONG
THE COAST. SEVERAL OF THE MORE EXPOSED LOCATIONS ALONG THE COAST
GUSTED INTO THE 70 TO 85 MPH RANGE WITH THE FIRST ROUND OF HIGH
WINDS.SOME OF THE WINDIER SITES MAY OCCASIONALLY STILL GUST ABOVE
HIGH WIND CRITERIA...BUT THE PEAK OF THE FIRST ROUND OF WINDS SHOULD
BE PAST US. HOWEVER...THIS REPRIEVE SHOULD ONLY LAST ANOTHER OR TWO
THOUGH. THE LATEST RUC BRINGS IN THE SECOND ROUND OF HIGH WINDS
ASSOCIATED WITH THE BENT BACK OCCLUSION TO THE NORTH CENTRAL OREGON
COAST BETWEEN 9PM AND 10PM. SATELLITE EXTRAPOLATION LINES UP NICELY
WITH THIS SCENARIO. SEVERAL SPOTTERS ACROSS THE INTERIOR OF THE COAST
RANGE NOTED DOWN TREES AND POWER OUTAGES ALREADY. THIS SECOND ROUND
OF WINDS WILL LIKELY CAUSE MANY MORE.
WITH THE FRONT PUSHING ACROSS THE WILLAMETTE VALLEY...THE GRADIENT
HAS FINALLY OPENED UP IN A MORE SOUTH TO NORTH DIRECTION. KEUG AND
KPDX SLP DIFFERENCE IS CURRENTLY 5.5MB. THE RUC...NAM AND GFS ALL
GENERALLY AGREE THE GRADIENT BETWEEN THESE TWO SITES WILL TOP OUT AT
APPROXIMATELY 10MB DURING THE EARLY MORNING HOURS ON MONDAY...BEFORE
BEGINNING TO WEAKEN AFTER 4AM. THEREFORE...THE HIGHEST WINDS STILL
LOOK ON TRACK FOR LATER TONIGHT. /NEUMAN
.LONG TERM...WEDNESDAY EVENING THROUGH FRIDAY...THE NEXT LARGE UPPER
LOW WILL DROP SOUTH FROM THE GULF OF ALASKA AND IMPACT THE FORECAST
AREA INTO THURSDAY. THIS LOW WILL BECOME NEARLY STATIONARY JUST OFF
THE PACIFIC NW COAST...SWINGING SEVERAL DISTURBANCES INTO THE
REGION. MODELS HAVE LOWERED SNOW LEVELS...BUT WILL KEEP THEM
HOVERING AROUND 1500 FT BY FRIDAY AND SATURDAY. ABUNDANT MOISTURE
WILL CONTINUE THROUGHOUT THE EXTENDED PERIOD...AS WELL AS BREEZY
CONDITIONS ALONG THE COAST AS THESE DISTURBANCES SWING THROUGH.
MODELS SUGGEST THE PARENT LOW WILL GRADUALLY MOVE INLAND LATE NEXT
WEEKEND...WITH POSSIBLY RIDGING BEHIND IT. /27
&&
.AVIATION...WIDESPREAD MVFR CIGS ACROSS REGION WITH RAIN. MVFR AND
LOCAL IFR WILL CONTINUE WELL INTO THIS EVENING. WARM FRONT LIFTS
ACROSS REGION BETWEEN 23Z AND 01Z...WITH STRONG SOUTHERLY WINDS
ON COAST AND BREEZY SOUTH WINDS INLAND. COLD FRONT ARRIVES BETWEEN
03Z AND 05Z. THIS WILL TURN WINDS S TO SW ACROSS ALL OF THE
REGION BUT REMAIN GUSTY. CIGS LIFT A BIT...BUT NOT MUCH CHANGE.
MAY SEE A FEW THUNDERSTORMS ALONG THE COAST BEHIND THE FRONT.
CASCADES REMAIN OBSCURED IN CLOUDS AND SNOW TODAY AND ESPECIALLY
TONIGHT INTO MON.
KPDX AND APPROACHES...VFR AT MOMENT...BUT SHOULD QUICKLY DROP TO
MVFR BY 00Z AS RAIN INCREASES. WILL REMAIN MVFR IN CLOUDS AND
RAIN THROUGH TONIGHT. STRONG WINDS ALOFT DEVELOPING AFTER 00Z AND
WITH LIGHT E-SE WINDS AT GROUND...WILL SEE LOW LEVEL WIND SHEAR
PROBLEMS BETWEEN 22Z AND 03Z. AFTER 03Z...WILL SEE SOUTH WINDS
KICK IN AT SURFACE WITH GUSTS 35 TO 45 KT. ROCKEY.
&&
.MARINE...NO CHANGES. DEVELOPING LOW WELL OFFSHORE WILL DEEPEN
RAPIDLY. 980 MB ABOUT 500 NM NW OF ASTORIA WILL MOVE EAST AND INTO
NW WASHINGTON LATER TONIGHT. WARM FRONT WILL LIFT N ACROSS THE
COASTAL WATERS EARLY THIS EVENING...FOLLOWED BY A STRONG COLD
FRONT LATER THIS EVENING. GUSTS TO 50 TO 60 KT LOOK GOOD...SO WILL
MAINTAIN CURRENT MARINE STORM WARNING.
LOW MAKES LANDFALL SOMEWHERE OVER NW WASHINGTON BETWEEN 06Z AND
10Z WITH THE NAM BEING THE SOONEST. THE LOW IS WEAKENING AS IT
MOVES ASHORE. THE WIND MAY EASE JUST A BIT LATE THIS EVENING...
BUT WINDS WILL TURN MORE WESTERLY AND INCREASE AGAIN WITH THE BACK
SIDE OF THE LOW. THIS WILL KEEP STORM FORCE GUSTS 45 TO 55 KT
LIKELY ACROSS THE S WASH/N OREGON COASTAL WATERS INTO MON AM.
SEAS WILL BUILD RAPIDLY...WITH 15 TO 18 FT SEAS THIS AFTERNOON
BUILDING TO 25 TO 30 FT THIS EVENING...POSSIBLY AS HIGH AS 32 FT
BETWEEN 11 PM TONIGHT AND 4 AM MON. HAVE ISSUED HIGH SURF WARNING
FOR LATER TONIGHT THROUGH MON AM. SOME POTENTIAL ALSO MINOR
COASTAL FLOODING IN LOW LYING SPOTS. ROCKEY.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER STORM WARNING UNTIL 6 PM THIS EVENING FOR CASCADES
OF LANE COUNTY AND NORTH OREGON.
BLIZZARD WARNING TONIGHT AND MON FOR CASCADES OF NORTH OREGON
AND LANE COUNTY.
HIGH WIND WARNING TONIGHT THROUGH MON AM FOR...
CENTRAL WILLAMETTE VALLEY
NORTH WILLAMETTE VALLEY...INCLUDING GREATER PORTLAND METRO
LOWER COLUMBIA
NORTHERN OREGON CASCADE FOOTHILLS.
HIGH WIND WARNING UNTIL 10 AM MON FOR CENTRAL OREGON COAST
AND CENTRAL COAST RANGE OF WESTERN OREGON
HIGH WIND WARNING UNTIL 1 PM MON FOR NORTH OREGON COAST AND
COAST RANGE OF NORTHWEST OREGON.
WIND ADVISORY UNTIL NOON MONDAY FOR SOUTH WILLAMETTE VALLEY.
HIGH SURF WARNING FROM 10 PM THIS EVENING TO NOON MONDAY FOR
THE NORTH AND CENTRAL OREGON COAST.
WA...WINTER STORM WARNING UNTIL 6 PM PST THIS EVENING FOR SOUTH
WASHINGTON CASCADES.
BLIZZARD WARNING FROM 6 PM THIS EVENING TO 6 PM PST MONDAY FOR
SOUTH WASHINGTON CASCADES.
HIGH WIND WARNING FROM 6 PM THIS EVENING TO NOON MONDAY FOR...
CLARK COUNTY AND THE GREATER VANCOUVER AREA
I-5 CORRIDOR IN COWLITZ COUNTY
SOUTH WASHINGTON CASCADE FOOTHILLS.
HIGH WIND WARNING THROUGH 1 PM MON FOR THE SOUTH WASHINGTON
COAST AND THE WILLAPA HILLS.
HIGH SURF WARNING FROM 10 PM THIS EVENING TO NOON MONDAY FOR
SOUTH WASHINGTON COAST.
PZ...STORM WARNING UNTIL 10 AM MONDAY ON ALL COASTAL WATERS.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR CONDITIONS THROUGH
TUESDAY.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...HTTP://WEATHER.GOV/PORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
529 PM CST SUN DEC 16 2012
.SHORT TERM...TONIGHT THROUGH WEDNESDAY
238 PM CST SUN DEC 16 2012
MAIN FORECAST CONCERNS ARE ON PRECIPITATION CHANCES AND TYPE FOR
TUESDAY AND WEDNESDAY.
CURRENTLY AS OF 20Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED A POTENT SHORTWAVE TROUGH APPROACHING THE PACIFIC NORTHWEST
AND BROAD TROUGHING ENCOMPASSING MUCH OF THE CENTRAL U.S. INTO THE
WESTERN GREAT LAKES. WITHIN THIS BROAD TROUGHING...THERE ARE VERY
FEW SHORTWAVES THAT LOOK TO HAVE ANY IMPACT ON OUR FORECAST AREA
DURING THE NEXT FEW DAYS. THE ONLY SHORTWAVE REALLY OF NOTE WAS OVER
WESTERN PORTIONS OF MONTANA AND WYOMING. AT THE SURFACE...LOW
PRESSURE WAS OVER UPPER MICHIGAN WHILE HIGH PRESSURE COVERED THE
DAKOTAS INTO WESTERN MINNESOTA. IN-BETWEEN THE TWO...NORTHERLY WINDS
ARE DRIVING COLDER LOW LEVEL AIR INTO THE FORECAST AREA. SURFACE
TEMPERATURES HAVE FALLEN INTO THE 20S OVER PORTIONS OF SOUTHEAST
MINNESOTA WHILE THE REST OF THE AREA REMAINS MOSTLY IN THE 30S. THE
COLD AIR EXTENDS UP TO 850MB WITH 12Z SOUNDINGS FROM BIS...ABR AND
MPX SHOWING -4C TEMPERATURES. ALONG WITH THE COLDER AIR...EXTENSIVE
LOW STRATUS EXISTS FROM THE DAKOTAS INTO THE FORECAST AREA...TRAPPED
BELOW A COLD FRONTAL/SUBSIDENCE INVERSION SHOWN ON THE
AFOREMENTIONED SOUNDINGS. AS THE COLD AIR HAS BEEN FLOWING IN...SOME
FOG HAS DEVELOPED...DUE TO RECENT RAIN AND MELTING SNOW.
VISIBILITIES DROPPED EVEN DOWN TO 1/4SM MILE IN SOME PLACES IN
SOUTHEAST MINNESOTA. LAST ITEM TO NOTE IS A QUICK SNOW DEPTH
COMPARISON TO OBSERVED. THE 16.12Z NAM HAS WAY TOO MUCH SNOW ALONG
AND SOUTH OF I-90...AS ITS SNOW DEPTH INFORMATION HAS NOT UPDATED
SINCE 00Z ON THE 15TH.
TONIGHT AND MONDAY...WEAK UPPER RIDGING WITHIN THE BROAD TROUGH IS
FORECAST TO BUILD INTO THE AREA FOR TONIGHT AND MUCH OF MONDAY...
AHEAD OF THAT SHORTWAVE OVER WESTERN MONTANA AND WYOMING. GOOD MODEL
AGREEMENT EXISTS THAT THE SHORTWAVE WILL REACH WESTERN MINNESOTA BY
00Z TUESDAY. THE WEAK UPPER RIDGING BUILDING IN COMBINED WITH THE
SURFACE RIDGING COMING IN AT THE SURFACE FAVORS DRY CONDITIONS
THROUGH MONDAY. THE BIGGEST QUESTION IS IF THIS STRATUS CAN
DISSIPATE AT ALL. TOUGH TO USE THE NAM...PARTICULARLY ALONG AND
SOUTH OF I-90...SINCE IT HAS TOO MUCH SNOW AND THIS IS INFLUENCING
ITS HANDLING OF BOUNDARY LAYER. HOWEVER...BOTH GFS AND RAP SOUNDINGS
WHICH HAVE A BETTER HANDLE ON THE SNOW DEPTH SITUATION SUGGEST THE
STRATUS WILL DEFINITELY STAY IN PLACE TONIGHT. LOOKS LIKE THERE IS
ENOUGH STIRRING OF THE BOUNDARY LAYER TO PREVENT MORE THAN PATCHY
FOG. PERHAPS THERE IS A SHOT OF DIURNAL MIXING OUT THE STRATUS
TOMORROW...THOUGH MID AND HIGH CLOUDS WILL INCREASE AHEAD OF THE
APPROACHING SHORTWAVE. AS A RESULT...MAINLY CLOUDY CONDITIONS WILL
PREVAIL. THIS MEANS TEMPERATURES FOR THE MOST PART ARE GOING TO BE
INFLUENCED BY ADVECTION. A BLEND OF GUIDANCE SEEMED REASONABLE FOR
BOTH LOWS AND HIGHS.
MONDAY NIGHT AND TUESDAY...THE SHORTWAVE OVER WESTERN MINNESOTA AT
00Z TUESDAY IS SLATED TO CROSS THE AREA MONDAY NIGHT...BUT IT LOOKS
LIKE IT WILL COME THROUGH WITH LITTLE FANFARE OUTSIDE OF SOME
MID/HIGH CLOUDS. THIS IS BECAUSE OF PLENTIFUL DRY AIR IN-BETWEEN
THESE MID/HIGH CLOUDS AND A POSSIBLE HANGING AROUND VERY LOW STRATUS
DECK. OF MORE SIGNIFICANCE IS LATE IN THE NIGHT AND HEADING INTO THE
DAY TUESDAY...WHEN WARM ADVECTION IMPACTS FROM THE POTENT TROUGH
APPROACHING THE PACIFIC NORTHWEST CURRENTLY BEGIN TO MOVE IN. AT 12Z
TUESDAY...MODELS SHOW THE POTENT TROUGH...ALBEIT IN A MUCH WEAKER
STATE AFTER CROSSING THE NORTHERN ROCKIES...STRETCHED FROM THE
DAKOTAS INTO NORTHWEST IOWA. THIS TROUGH SLIDES EAST THROUGH MUCH OF
THE AREA ON TUESDAY...IN RESPONSE TO BUILDING 500MB HEIGHTS
DOWNSTREAM OF DEEP TROUGHING COMING INTO CALIFORNIA. MODELS HAVE
COME INTO GOOD AGREEMENT SHOWING A BAND OF ISENTROPIC LIFT/MID-LEVEL
FRONTOGENESIS ACCOMPANYING THIS TROUGH PASSAGE...YIELDING A BAND OF
QPF LIFTING NORTHWARD THROUGH THE FORECAST AREA DURING THE DAY
TUESDAY. PRECIPITATION COULD DEVELOP AS EARLY AS AFTER MIDNIGHT
MONDAY NIGHT AS SUGGESTED BY THE 16.12Z GFS AND SOME OF THE 16.09Z
SREF ENSEMBLES. HAVE CONFINED A 20 PERCENT CHANCE FOR MONDAY NIGHT
TO SOUTHEAST MINNESOTA. GIVEN THE GOOD AGREEMENT FOR TUESDAY...
INCREASED CHANCES UP TOWARDS 50...HIGHEST NORTH OF I-90 WHERE THE
BEST CONSENSUS EXISTS. HIGHER CHANCES MAY BE NECESSARY IN FUTURE
FORECASTS. AMOUNTS DO NOT LOOK LIKE A WHOLE LOT...BETWEEN THE BAND
LIFTING NORTH AND LIFT THAT IS QUALITATIVELY MODERATE AT BEST.
PRECIPITATION TYPE COULD BE AN ISSUE...WITH THE 16.12Z NAM SHOWING A
WARM NOSE AROUND 2C AROUND 2000 FT AGL ACCOMPANYING THE BAND. THE
GFS SUGGESTS ALL SNOW AND WILL PLAY THAT ROUTE FOR NOW AS IT SEEMS
THAT THE WARM NOSE SHOULD ACTUALLY COME IN SOUTH OF THE BAND. AFTER
THE PASSAGE OF THE BAND...THE GFS AND NAM SHOWS SKIES CLEARING OUT.
THIS MAY OCCUR AND IF IT DOES...TEMPERATURES SOUTH OF I-90 COULD POP
INTO THE 40S. FOR NOW TAKING A CONSENSUS APPROACH AS THE ECMWF
SUGGESTS A SLOWER LIFT NORTH OF THE BAND.
TUESDAY NIGHT AND WEDNESDAY...ATTENTION BEGINS TO SHIFT TO THE
TROUGHING OVER CALIFORNIA AT 00Z WEDNESDAY. GOOD MODEL AGREEMENT
EXISTS OF IT SLIDING ACROSS ARIZONA AND NEW MEXICO DURING THIS
PERIOD...RESULTING IN DEEPENING LOW PRESSURE ACROSS THE OKLAHOMA AND
TEXAS PANHANDLES. DOWNSTREAM...500MB HEIGHTS CONTINUE TO RISE...
PARTICULARLY ACROSS THE LOWER AND MID-MISSISSIPPI RIVER VALLEY. THIS
IN TURN SETS UP A STRENGTHENING MID-LEVEL FRONTOGENESIS ZONE
INITIALLY ACROSS COLORADO...THEN SPREADING UP THROUGH KANSAS...
EASTERN NEBRASKA AND EVENTUALLY IOWA BY WEDNESDAY AFTERNOON. THE
16.12Z NAM APPEARS TO BE AN OUTLIER IN EJECTING THE SURFACE SYSTEM
NORTH TO KANSAS CITY BY 00Z THURSDAY...COMPARED TO THE
GFS/ECMWF/UKMET/CANADIAN WHICH ALL HOLD IT BACK OVER OKLAHOMA. THE
FASTER EJECTING NAM WOULD ALLOW WARMER AIR TO ENTER SOUTHERN
SECTIONS OF THE FORECAST AREA ON WEDNESDAY AS WELL AS PRECIP INTO
SOUTH CENTRAL MINNESOTA. THE LATTER MORE FAVORED GROUP REQUIRES
HAVING SOME CHANCES OF PRECIPITATION...SNOW OR RAIN/SNOW MIX...TO
SOUTHERN SECTIONS OF THE FORECAST AREA WEDNESDAY AFTERNOON.
OTHERWISE...THE REST OF THE PERIOD IS DRY. WEAK PRESSURE GRADIENT
AFTER MIDNIGHT TUESDAY NIGHT PLUS POSSIBLE CLEARING WOULD
RESULT IN GOOD RADIATIONAL COOLING CONDITIONS...THOUGH THE EXTENT OF
CLEARING IS UNCERTAIN AT THIS TIME. PLUS...MID/HIGH CLOUDS MAY
ALREADY BE APPROACHING THE AREA ASSOCIATED WITH THE FRONTOGENESIS
TUESDAY NIGHT...THICKENING OVER THE AREA ON WEDNESDAY. THUS HAVE
STAYED TOWARD A GUIDANCE BLEND FOR BOTH HIGHS AND LOWS.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
238 PM CST SUN DEC 16 2012
FOCUS CONTINUES TO BE ON THE DEEP TROUGHING COMING OUT OF NEW MEXICO
AND THE ASSOCIATED SURFACE SYSTEM IN OKLAHOMA.
ECMWF/CANADIAN/GFS/UKMET AND GFS ENSEMBLES ALL STILL SUGGEST PHASING
OF THIS TROUGHING AND A NORTHERN STREAM TROUGH DROPPING DOWN INTO
THE NORTHERN PLAINS. HOWEVER...TRENDS OF THE ABOVE MODELS ARE ALL
SHOWING THIS PHASING TAKING PLACE FARTHER EAST WITH THE TRACKS NOW
MAINLY GOING UP THROUGH INDIANA. THIS TREND IS GETTING CONCERNING
FOR PRECIPITATION FOR WEDNESDAY NIGHT AND THURSDAY...ESPECIALLY
OVER THE NORTHWEST 1/3 OR SO WHERE IT COULD END UP DRY. CERTAINLY
PLENTY OF TIME FOR ADJUSTMENTS FOR THE TRACK GIVEN THAT THE DEEP
TROUGH PORTION IS STILL SOUTH OF THE ALEUTIANS. ADJUSTED THE
PRECIPITATION CHANCES SLIGHTLY DOWNWARD FOR WEDNESDAY NIGHT AND
THURSDAY TO ACCOUNT FOR THE SOUTHEAST TREND...BUT AT LEAST AT THIS
TIME THE SOUTHEAST HALF OF THE FORECAST AREA STILL LOOKS GOOD TO
PICK UP SOME ACCUMULATING SNOW.
AFTER THE WEDNESDAY NIGHTTHURSDAY SYSTEM...THE PATTERN LOOKS QUIET
WITH UPPER RIDGING DOMINATING THE WESTERN HALF OF THE U.S. OR SO AND
THE FORECAST AREA IN WEST TO NORTHWEST FLOW AND HIGH PRESSURE AT THE
SURFACE. CERTAINLY SOME COLDER AIR WILL COME DOWN IN THE WAKE OF THE
SYSTEM...SENDING TEMPERATURES DOWN TO NEAR OR JUST BELOW NORMAL...
BUT IT APPEARS THIS WILL BE SHORT-LIVED AS 500MB HEIGHTS RISE.
&&
.AVIATION...TONIGHT AND MONDAY
529 PM CST SUN DEC 16 2012
LOW LEVEL MOISTURE REMAINS TRAPPED UNDER AN INVERSION WHICH
REMAINS IN PLACE THROUGH MUCH OF THE TAF PERIOD. THUS EXPECT THE
IFR CONDITIONS TO CONTINUE AT LEAST THROUGH 15Z MONDAY. AT THAT
TIME CEILINGS MAY RISE INTO THE LOWER END MVFR CATEGORY AT
KLSE...BUT LIKELY WILL REMAIN UNDER 010K FEET AT KRST.
VISIBILITIES EXPECTED IN THE 1-4SM RANGE OVERNIGHT AND THEN SLOWLY
RISE LATER MONDAY MORNING AND INTO THE AFTERNOON.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
238 PM CST SUN DEC 16 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...RABERDING
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 06Z MONDAY
1126 PM CST SAT DEC 15 2012
SURFACE LOW NOW OVER WESTERN WISCONSIN WILL CONTINUE TO PULL
NORTHEAST TONIGHT. WRAP AROUND MOISTURE ON ITS BACK SIDE WAS
PUSHING THROUGH SOUTHEAST MINNESOTA AND WILL PASS ACROSS THE TAF
SITES THROUGH THE OVERNIGHT HOURS. VISIBILITIES HAVE IMPROVED AT
KRST DUE TO THE WIND SHIFT AND LIGHT PRECIPITATION. EXPECT THIS TO
OCCUR AT KLSE AROUND 08Z. THE TRANSITION FROM LIQUID TO SNOW WILL
OCCUR AT KRST BETWEEN 06Z-08Z AND AT KLSE BETWEEN 10Z-12Z. ONE
CONCERN IS RAP AND NAM BUFKIT SOUNDINGS SHOWING A LOSS OF ICE AND
THUS MAYBE SOME LIGHT FZDZ FOR A PERIOD OF TIME LATER THIS MORNING
BEFORE THE PRECIPITATION ENDS AND DID INCLUDE A TEMPO GROUP AT
BOTH SITES. OTHERWISE...CEILINGS WILL REMAIN IFR THROUGH AT LEAST
18Z AND MAY RISE INTO THE LOWER MVFR CATEGORY FOR THE AFTERNOON.
WITH THE MOISTURE TRAPPED UNDER THE INVERSION...SOME CONCERN AS TO
LOWERING CEILINGS/VISIBILITIES ONCE AGAIN AFTER 00Z AS COLUMN
COOLS.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
831 PM CST SAT DEC 15 2012
WI...DENSE FOG ADVISORY UNTIL 6 AM CST SUNDAY FOR WIZ017-029-032>034-
041>044-053.
MN...DENSE FOG ADVISORY UNTIL 6 AM CST SUNDAY FOR MNZ079-088-096.
IA...DENSE FOG ADVISORY UNTIL 6 AM CST SUNDAY FOR IAZ011.
&&
$$
SHORT TERM...RABERDING
LONG TERM...AJ
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
1021 PM PST SUN DEC 16 2012
.SHORT TERM DISCUSSION...
UPPER LOW IS JUST WEST OF PUGET SOUND WITH TROUGH ALONG THE COAST.
STRONG JET STREAM ENERGY WITH THIS SYSTEM IS PUSHING ACROSS
NORCAL THIS EVENING WITH HEAVY PRECIP DEVELOPING OVER NRN LAKE AND
SHASTA COUNTIES. ALSO STRONG UPSLOPE FLOW IS OVER THE SIERRA IN
WESTERN PLUMAS COUNTY FROM BUCKS LAKE WEST. RUC IS DEPICTING 1 TO
2 FEET IN THIS AREA...WHICH IS RIGHT ON CURRENT FORECAST
ACCUMULATIONS. SNOW LEVELS ARE CURRENTLY NEAR 5200 FEET OVER THE
SIERRA AND 3000 FEET OVER SHASTA COUNTY. TIGHT SURFACE GRADIENT
HAS SET UP OVER THE NRN SACRAMENTO VALLEY AHEAD OF FRONTAL SYSTEM
WITH SUSTAINED WINDS 25 TO 30 MPH GUSTS TO 45 MPH RED BLUFF TO
REDDING HAVE ISSUED A WIND ADVISORY THROUGH 4 AM AND UPDATED WINDS
GRIDS TO REFLECT THIS. EXPECT WINDS TO DIMINISH WITH PASSAGE OF
FRONT AROUND 4 AM. RAIN SHOULD BEGIN IN THE SRN SAC VALLEY AFTER
MIDNIGHT WITH THE BULK OF THE PRECIP BETWEEN 2-6 AM AHEAD OF
FRONTAL BOUNDARY. WINDS COULD ALSO BE BREEZY THROUGH MID MORNING
UNTIL FRONT PASSES...BUT WILL DIMINISH IN THE AFTERNOON.
PREVIOUS DISCUSSION...
SHORT-WAVE RIDGE OVER NORCAL BEGINNING TO GIVE WAY AHEAD OF
STRONGER WAVE THAT WILL MOVE ONSHORE TONIGHT AND SPREAD SOUTH
MONDAY. STRONG WARM ADVECTION CONTINUES TO BRING MOSTLY LIGHT
AMOUNTS OF PRECIP MAINLY TO THE NORTH OF I-80. LOW SNOW LEVELS
REMAIN LOCKED IN NORTH OF REDDING...BUT SOME INCREASE IN SNOW
LEVEL IS EXPECTED LATER TONIGHT AS STRONGER SOUTHERLY FLOW
ATTEMPTS TO SCOUR OUT THE REMAINING COLD AIR.
HEAVIER PRECIP WILL DEVELOP LATER TONIGHT AND SPREAD SOUTH ON
MONDAY AS THE COLD FRONT MOVES THROUGH. TIMING STILL LOOKS LIKE
THE FRONT WILL MAKE IT TO THE SAC AREA AROUND MIDDAY MONDAY.
SCATTERED SHOWERS EXPECTED BEHIND THE FRONT MONDAY AFTERNOON.
CONTINUING UPSLOPE FLOW AND CAA WILL CONTINUE SHOWERS OVER THE
WEST SLOPES OF THE NORTHERN SIERRA MONDAY NIGHT INTO TUESDAY WHILE
THE VALLEY IS EXPECTED TO SEE A DIMINISHING THREAT OF SHOWERS AS
SUBSIDENCE AND NORTHWESTERLY FLOW TAKE HOLD. THE HEAVIEST PERIOD
OF SNOW ALONG I-80 APPEARS TO BE FOCUSED FROM LATER TONIGHT
THROUGH MONDAY WITH WELL OVER A FOOT OF SNOW EXPECTED ABOVE 5000
FEET ELEVATION.
MOSTLY DRY WEATHER EXPECTED WEDNESDAY AS UPPER RIDGE MOVES OVHD
NORCAL...THOUGH INCREASING WARM ADVECTION AHEAD OF THE NEXT
STRONGER SYSTEM LIKELY TO BRING SOME LIGHT PRECIP BACK INTO THE
NORTHERN MOUNTAINS BY THE AFTERNOON.
&&
.EXTENDED DISCUSSION (THURSDAY THROUGH SUNDAY)
MORE PRECIPITATION AND PERIODS OF BREEZY AND GUSTY SOUTHERLY
WINDS AS A BROAD TROUGH OFFSHORE ROTATES SEVERAL SHORTWAVES
THROUGH THE AREA. PRECIPITATION MAY STAY MAINLY NORTH OF INTERSTATE
80 WEDNESDAY NIGHT BUT SPREAD SOUTH DURING THE DAY THURSDAY AS AN
INCH PW PLUME MOVES SOUTH ALONG THE COAST. SNOW LEVELS WILL BE
AROUND 500 FT IN SHASTA COUNTY TO AROUND 2500 FT ALONG THE SIERRA
WEDNESDAY NIGHT INTO THURSDAY MORNING AND RISE TO AROUND 2000 TO
4000 FT BY THURSDAY EVENING. SNOW WILL BE POSSIBLE AROUND REDDING
WEDNESDAY NIGHT INTO THURSDAY MORNING WITH COLD AIR POSSIBLY BEING
TRAPPED IN THE VALLEY. SNOW LEVELS ARE EXPECTED TO RISE TO AROUND
3000 TO 5000 FT ON SATURDAY AND DROP AGAIN TO AROUND 2000 TO 3500
FEET ON SUNDAY. ALTHOUGH THERE IS STILL SOME UNCERTAINTY IN
WEEKEND FORECAST DUE TO VARIABILITY IN THE TIMING OF THE TROUGH
MOVING INLAND. MODELS STILL VARY WITH WHEN THIS TROUGH MAY MOVE
INLAND WITH THE ECMWF MOVING THE TROUGH ONSHORE ON SUNDAY AND THE
18Z OPERATIONAL GFS HOLDING IT OFFSHORE BUT THE GFS ENSEMBLE MEAN
IS IN BETWEEN THE TWO ON TIMING. PRECIPITABLE WATER VALUES AROUND
AN INCH WITH A PLUME OFF THE COAST THURSDAY AND SUNDAY. AROUND AN
INCH TO 3 INCHES OF RAIN ARE POSSIBLE IN THE SACRAMENTO VALLEY AND
POSSIBLY UP TO AN INCH IN THE NORTHERN SAN JOAQUIN VALLEY AND
SEVERAL FEET OF SNOW ARE POSSIBLE OVER THE MOUNTAINS THURSDAY
THROUGH SUNDAY.
&&
.AVIATION...
LOW PRESSURE SYSTEM WILL BRING WIDESPREAD PRECIP ALONG WITH BREEZY
SOUTHERLY WINDS HIS EVENING AS A COLD FRONT APPROACHES. WIND GUSTS
IN THE VALLEY WILL REACH UP TO 26 TO 32 KT TONIGHT.
VFR/MVFR CONDITIONS WILL CDEVELOP FOR SAC METRO TAF SITES AND
KSCK TONIGHT WITH PERIODS OF RAIN. IFR AND LOCAL LIFR CONDITIONS
WILL BE POSSIBLE OVER THE NORTHERN SACRAMENTO VALLEY. SNOW LEVELS
OTHERWISE AROUND 2000 FEET WITH IFR/LIFR CONDITIONS FROM SNOW
CONTINUING THROUGH MONDAY IN THE FOOTHILLS AND MOUNTAINS. SNOW
LEVELS AROUND 1000 TO 2000 FEET OVER SHASTA COUNTY AND TO 4500
FEET OVER THE SIERRA TONIGHT.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL MIDNIGHT PST MONDAY NIGHT BURNEY
BASIN / EASTERN SHASTA COUNTY...WEST SLOPE NORTHERN SIERRA
NEVADA...WESTERN PLUMAS COUNTY/LASSEN PARK.
WIND ADVISORY UNTIL 4 AM PST MONDAY NORTHERN SACRAMENTO VALLEY.
WINTER STORM WARNING UNTIL 4 AM PST MONDAY ABOVE 1500 FEET FOR
THE SHASTA LAKE AREA / NORTHERN SHASTA COUNTY.
&&
$$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
411 AM EST MON DEC 17 2012
.SHORT TERM /TODAY THROUGH TUESDAY/...
MAIN FCST CONCERN REMAINS CHC FOR SVR CONVECTION TODAY. 00Z MODEL
RUNS NOT SHOWING MUCH CHANGE FROM PREVIOUS RUNS...BEST TIMING FOR
VERTICAL WIND SHEAR AND INSTABILITY WILL BE 15Z-21Z. PROBLEM IS
THAT WE SAW NORTH WINDS MUCH OF THE DAY AND EVENING SUNDAY...IN
RESPONSE TO LOW FROM LARGE PERSISTENT PRECIP AREA...WHICH MINIMIZED
NORTHWARD MOISTURE TRANSPORT. LATEST RAP ANALYSIS ALSO SHOWING THAT
MUCAPE REMAINS NEAR ZERO IN THE REGION EXCEPT ALONG THE GULF COAST.
USUALLY SEE ELEVATED INSTABILITY SURGING NORTHEAST AT THIS TIME OF
NIGHT PRECEDING FRONT AND STORMS. 06Z NAM STARTING TO AGREE WITH
LATEST ANALYSIS IN THE NEAR TERM BUT STILL APPEARS A LITTLE TOO
QUICK BRINGING HIGHER THETA-E AIR AND HIGHER CAPE NORTH BY 15Z.
ASSUMING MODELS ON TRACK WITH INSTABILITY...SHOULD SEE SVR THREAT
DEVELOP AFTER 15Z. DO NOT SEE ANY THREAT OF HAIL GREATER THAN ONE
INCH. DAMAGING WINDS AND AN ISOLATED TORNADO THREAT REMAIN POSSIBLE
BUT CONTINGENT ON MOISTURE TRANSPORT AND INSTABILITY DEVELOPING AS
FCST. WILL HAVE TO WATCH REAL TIME ANALYSIS CLOSELY THIS MORNING.
PRECIP WILL MOVE OUT QUICKLY TONIGHT. NO ISSUES WITH FCST BEYOND
THIS. DRY AIR SHOULD FILTER IN SLOWLY BUT ENOUGH TO PRECLUDE
DEVELOPMENT OF FOG. USED MAV/MET/ECMWF MOS BLEND FOR TEMPS.
SNELSON
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
MAIN FORECAST CONCERN IN THE EXTENDED PERIODS IS THE FAIRLY STRONG
COLD FRONT EXPECTED ON THURSDAY. WEAK RIDGING OVER THE SOUTHEAST
AT THE BEGINNING OF THE EXTENDED PERIODS...WITH NEARLY NEARLY
ZONAL UPPER LEVEL FLOW...SFC HIGH AND DRY CONDITIONS ON WEDNESDAY.
ALTHOUGH THERE ARE SOME DISCREPANCIES EXTENDED MODELS ARE IN GOOD
AGREEMENT WITH GENERAL PATTERN MIDWEEK. AN UPPER LEVEL SHORT WAVE
CROSSES THE ROCKIES ON WEDNESDAY LIFTING INTO THE OHIO VALLEY BY
THURSDAY AFTERNOON. GFS IS DEEPER AND CUTS OFF THE LOW BY THURSDAY
AFTERNOON...ECMWF IS SLOWER TO CUT OFF LOW BUT BY THURSDAY NIGHT
BOTH MODELS ARE SIMILAR IN LOCATION AND STRENGTH OF LOW. WITH WEAK
RIDGING AND SURFACE HIGH SHIFTING EAST ON WEDNESDAY MODELS ARE IN
AGREEMENT THAT BEST MOISTURE RETURNS THURSDAY MORNING AHEAD OF THE
COLD FRONT WHICH MOVES ACROSS THE FORECAST AREA RATHER QUICKLY BY
THURSDAY EVENING. INSTABILITY IS LIMITED HOWEVER BOTH GFS AND
ECMWF AREA SHOWING GOOD SHEAR...AND GIVEN THE STRENGTH OF THE FRONT
WILL CONTINUE ISOLATED THUNDERSTORMS DURING THE DAY. RAINFALL
RATES WILL BE HALF INCH OR LESS BASED UPON THE SPEED OF THE STORM.
ZONAL FLOW ALOFT AND SURFACE HIGH PRESSURE BUILD BACK IN FOR THE
WEEKEND. GFS SHOWING SOME MOISTURE RETURN SATURDAY BUT MAINLY
EXPECT AN INCREASE IN CLOUDS ACROSS THE FORECAST AREA SATURDAY AND
SUNDAY. GUIDANCE TEMPERATURES ARE PRETTY CLOSE AND WILL TAKE A
BLEND OF MAV/ECMWF MOS THROUGH THE EXTENDED PERIODS.
ATWELL
&&
.PREV DISCUSSION... /ISSUED 137 AM EST MON DEC 17 2012/
AVIATION...
06Z UPDATE...
PRIMARY CONCERN IS DEVELOPMENT OF LIFR CIGS AND VSBYS THIS
MORNING AND TSRA LIKELIHOOD THIS AFTERNOON. CIGS AND VSBYS NOW
FALLING QUICKLY AS PRECIP HAS ENDED AND MOIST SFC AND RADIATIONAL
COOLING IS ENHANCING STRATUS LAYER. LIFR LIKELY TO PERSIST THROUGH
15Z WHEN NEXT BAND OF PRECIP TO MOVE IN. TSRA MORE LIKELY TODAY
THAN LAST 24 HRS WITH BETTER INSTABILITY. WILL UP CHCS TO TEMPO
FOR TSRA BETWEEN 16-22Z AT ATL AND SIMILAR TIMES AT OTHER TAF
SITES. SE WINDS WILL SHIFT TO SSW AROUND WHEN PRECIP STARTS IN THE
LATE MORNING. CLOUDS AND PRECIP WILL KEEP SPEEDS FROM GETTING TOO
STRONG BUT BY MID AFTERNOON...COULD SEE A FEW GUSTS OF 15-18KTS.
PRECIP SHOULD END BY 00Z.
//ATL CONFIDENCE...06Z UPDATE...
MEDIUM CONFIDENCE ON TSRA TIMING.
HIGH ON ALL OTHER ELEMENTS.
SNELSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 62 47 62 36 / 80 10 5 5
ATLANTA 64 47 61 41 / 90 10 5 5
BLAIRSVILLE 57 41 56 29 / 90 10 5 5
CARTERSVILLE 63 42 59 32 / 100 10 5 5
COLUMBUS 69 50 65 40 / 80 10 5 5
GAINESVILLE 60 45 60 39 / 90 10 5 5
MACON 70 49 66 35 / 80 20 5 5
ROME 64 41 60 33 / 90 10 5 5
PEACHTREE CITY 66 42 62 32 / 90 10 5 5
VIDALIA 74 56 69 42 / 80 40 0 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SNELSON
LONG TERM....ATWELL
AVIATION...SNELSON
AREA FORECAST DISCUSSION
NWS LINCOLN IL
230 AM CST MON DEC 17 2012
.DISCUSSION...
ISSUED 230 AM CST MON DEC 17 2012
PRIMARY FOCUS FOR THIS FORECAST INVOLVES THE MAJOR STORM SYSTEM
THAT WILL BE CROSSING THE MIDWEST WEDNESDAY NIGHT AND THURSDAY...
INCLUDING PRECIPITATION TYPES AND STRONG WINDS. RAIN POTENTIAL
LATER TODAY IS A SECONDARY CONCERN.
SHORT TERM...TODAY THROUGH TUESDAY...
MAIN FOCUS FOR ANY RAIN TODAY IS WITH A SURFACE LOW CURRENTLY OVER
SOUTH CENTRAL MISSOURI...WITH A FRONTAL BOUNDARY ARCING NORTHEAST
ALONG THE OHIO RIVER. BEST PRECIPITATION CHANCES WILL BE NEAR THE
OHIO VALLEY AS THE LOW RIDES UP THE BOUNDARY...BUT SOME OF THE
RAIN FROM THIS SYSTEM MAY REACH INTO SOUTHEAST ILLINOIS. IN
ADDITION...A SHORTWAVE CURRENTLY OVER KANSAS/OKLAHOMA WILL SWING
ACROSS ILLINOIS THIS AFTERNOON. GFS AND CANADIAN MODELS DEVELOP
SOME LIGHT QPF FROM MISSOURI NORTHEAST INTO CENTRAL ILLINOIS
PRIMARILY THIS AFTERNOON...ALTHOUGH SOUNDINGS OFF THE RAP MODEL
SHOW QUITE A BIT OF DRY AIR ABOVE THE PERSISTENT INVERSION AROUND
900 MB. HIGHEST POPS TODAY WILL MAINLY BE SOUTH OF I-72...BUT WILL
CARRY SOME SLIGHTS NORTHWEST OF THE ILLINOIS RIVER. ANOTHER
SHORTWAVE WILL TRACK INTO THE WESTERN GREAT LAKES ON TUESDAY...BUT
IT STILL APPEARS ANY ASSOCIATED PRECIP WITH THIS FEATURE WILL
REMAIN TO OUR NORTH.
LONG TERM...WEDNESDAY THROUGH SUNDAY...
A STRONG UPPER WAVE COMING ONTO THE PACIFIC COAST ON TUESDAY IS
STILL ON TRACK TO HELP DEVELOP A MAJOR STORM SYSTEM ACROSS THE
CENTRAL PLAINS ON WEDNESDAY. STILL A FAIR AMOUNT OF SPREAD AMONG
THE EVENING MODELS ON TIMING AND PLACEMENT OF THE CENTRAL
LOW. EACH MODEL SHOWING SOME CONSISTENCY WITH ITS PREVIOUS
RUN...BUT NOT AMONGST EACH OTHER...WITH THE NAM THE FURTHEST
NORTHWEST AND THE ECMWF THE FURTHEST SOUTH. THIS IS GOING TO BE
CRITICAL IN DETERMINING THE EXACT PLACEMENT OF HEAVY SNOW ACROSS
PORTIONS OF THE MIDWEST. GIVEN THAT THE PARENT WAVE HAS NOT BEEN
ADEQUATELY SAMPLED BY THE UPPER AIR NETWORK YET...THESE
INCONSISTENCIES ARE NOT UNUSUAL.
THIS FORECAST PACKAGE WILL GO WITH A GFS/ECMWF BLEND...WITH THE
LOW ROUGHLY PARALLELING THE ILLINOIS RIVER LATE WEDNESDAY NIGHT
AND EARLY THURSDAY. RAIN IS EXPECTED TO OVERSPREAD THE AREA
WEDNESDAY EVENING...WITH SOME POTENTIAL FOR THUNDER IN THE
SOUTHEAST CWA LATE WEDNESDAY NIGHT IN THE WARM SECTOR. THE COLD
AIR WILL RAPIDLY POUR IN BEHIND THE LOW ON THURSDAY MORNING...WITH
FORECAST SOUNDINGS SHOWING A FAIRLY CLEAN AND RAPID TRANSITION
FROM RAIN TO SNOW GOING FROM WEST TO EAST ACROSS THE CWA. HEAVIEST
SNOWFALL IN THE DEFORMATION ZONE WOULD BE MORE ACROSS EASTERN IOWA
INTO SOUTHERN WISCONSIN...BUT AN INCH OR TWO OF SNOW IS POSSIBLE
NORTH OF A BLOOMINGTON TO CANTON LINE. ACCUMULATIONS MAY BE
HAMPERED BY THE UNSEASONABLY WARM GROUND...BUT A HEAVY FALLING
SNOW MAY BE ENOUGH TO OVERCOME THAT. WHAT SNOW DOES FALL WILL BLOW
AROUND QUITE A BIT...AS ALL MODELS SHOW VERY WINDY CONDITIONS
DEVELOPING THURSDAY AS THE LOW PULLS AWAY. BUFKIT SOUNDINGS OFF
THE GFS SHOW SURFACE GUSTS AROUND 45 MPH THURSDAY AFTERNOON AND
EARLY EVENING. ANY LINGERING SNOW SHOULD TAPER OFF THURSDAY
EVENING.
THE REMAINDER OF THE FORECAST PERIOD IS EXPECTED TO BE QUIET...
WITH TEMPERATURES RUNNING BELOW NORMAL.
GEELHART
&&
.AVIATION...
ISSUED 1145 PM CST SUN DEC 16 2012
PERSISTENT LOW LEVEL CLOUDS AND MVFR CONDITIONS WILL BE THE RULE
MUCH OF THE TAF PERIOD OVERNIGHT AND THROUGH THE DAY ON MONDAY.
THERE SHOULD BE A BRIEF TIME PRIOR TO OR AROUND DAYBREAK WHEN IFR
CIGS ARE ANTICIPATED. A FEW TAF SITES ARE ALREADY WITHIN 100-300
FT OF IFR CEILINGS...SO CONFIDENCE IS FAIRLY HIGH THIS WILL OCCUR.
INCREASING HIGH AND MID LEVEL CLOUDINESS DURING THE EARLY MORNING WILL
KEEP THE LOW CLOUDS AND MVFR CIGS IN PLACE THROUGH THE MORNING AND
MUCH OF THE AFTERNOON. PARTS OF CENTRAL IL SOUTHEAST OF A KSPI-
KCMI LINE WILL BE ON THE NORTHERN FRINGES OF SOME LIGHT RAIN AS A
RESULT OF A SHORTWAVE MOVING INTO THE OHIO VALLEY. HAVE INTRODUCED
VCSH INTO THE TAF DURING THE AFTERNOON AS A RESULT.
A SHIFT OF THE MAIN UPPER LEVEL SHORTWAVE TROF AXIS TO OUR EAST
DURING THE LATE AFTERNOON AND EVENING MONDAY WILL RESULT IN
SUBSIDENCE...SOMEWHAT DRIER AIR...AND AN EVENTUAL END TO THE MVFR
CONDITIONS.
MILLER
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1140 PM CST SUN DEC 16 2012
.UPDATE...
HAVE UPDATED THE FORECAST TO REMOVE PRECIPITATION WORDING AS MUCH OF
THE LIGHT RAIN/SNOW HAS DISSIPATED ACROSS CENTRAL IOWA. ALSO HAVE
INCREASED AREA OF PATCHY FOG MENTION TO INCLUDE NORTHWESTERN CWA
THIS EVENING...AND UPGRADED ALL FOG MENTION LATE TONIGHT TO AREAS OF
FOG VERSUS THE PATCHY IN THE PREVIOUS GRIDS. BUFKIT SOUNDINGS
SHOWING DECENT SATURATION NEAR THE SURFACE LATE TONIGHT WITH LOW
STRATUS ACROSS NORTHWESTERN IOWA/SRN MN STILL EXPECTED TO CONTINUE
PROGRESSING SOUTH SOUTHEASTWARD OVERNIGHT. AREAS BENEATH THE LOWER
CLOUDS ALREADY DROPPING INTO THE 1/2 MILE TO 2 MILE RANGE...SO
EXPECT AREAS ESPECIALLY ACROSS NORTHERN IOWA TO DROP OFF LATE
TONIGHT AS TEMPERATURES CONTINUE TO COOL OFF A BIT MORE AND
DEWPOINTS REMAIN IN THE MID TO UPPER TEENS.
.SHORT TERM /TONIGHT/...
CHALLENGING FORECAST ESPECIALLY FROM A FOG AND LOW CLOUDS
PERSPECTIVE. FOG AND LOW CLOUDS HAVE BEEN STUBBORN IN LIFTING TODAY
ESPECIALLY ACROSS THE SOUTHERN...CENTRAL AND EASTERN CWA. AND IN THE
NORTHWESTERN CWA WHERE THE FOG AND LOW CLOUDS DID LIFT...ANOTHER
AREA OF LOW CLOUDS HAS BEEN MOVING SOUTHEAST FROM SOUTH DAKOTA AND
MINNESOTA.
HAVE TAKEN A SOMEWHAT PESSIMISTIC APPROACH TO THE LOW CLOUDS AND FOG
FOR TONIGHT. ALTHOUGH BUFKIT NAM SOUNDINGS ARE OPTIMISTIC...THE
BUFKIT RAP SOUNDINGS ARE QUITE PESSIMISTIC. THE FORECAST TENDS TO
SPLIT THE DIFFERENCE WITH A LEAN TOWARD THE LOW CLOUDS AND FOG BEING
STUBBORN. LOW LEVEL MOISTURE IS EXPECTED TO REMAIN PLENTIFUL
OVERNIGHT ESPECIALLY IN THOSE AREAS THAT STILL HAVE LOW CLOUDS AND
FOG. WITH WIND SPEEDS DECREASING OVERNIGHT...MIXING WILL DIMINISH
AND THE FOG IS EXPECTED TO COME BACK. THUS HAVE GONE WITH PATCHY FOG
WORDING IN MANY AREAS FOR TONIGHT/S FCST GRIDS. IN THE NORTHWESTERN
CWA...HAVE BROUGHT THE CLOUDS BACK IN ALONG WITH THE POSSIBILITY OF
PATCHY FOG THERE AS WELL. THE LOWEST VISIBILITIES IN THE FOG ARE
EXPECTED TO BE IN THE NORTHEASTERN CWA.
ON A DIFFERENT NOTE...SOME WEAK FRONTOGENETICAL FORCING HAS LED TO
AN AREA OF ECHOES ON THE RADAR MAINLY ACROSS THE WESTERN CWA TODAY.
OVER TIME THE ECHOES HAVE SPREAD EASTWARD...INDICATING THAT THE
FORCING IS TRANSLATING EASTWARD...WHICH IS SUPPORTED BY MODEL CROSS
SECTIONS. SINCE THE PRECIP IS NOT EXPECTED TO REACH THE GROUND
MUCH...IF AT ALL...HAVE GONE ONLY WITH SLIGHT CHANCE POPS ACROSS THE
SOUTHERN CWA INTO THIS EVE. THERE IS A DRY ENOUGH LAYER BETWEEN THE
LAYER OF FORCING AND THE LOWER LEVEL MOISTURE THAT THE PRECIP IS NOT
EXPECTED TO MAKE IT THROUGH THAT DRIER LAYER.
.LONG TERM /MONDAY THROUGH SUNDAY/...
A PAIR OF SUCCESSIVE 500 MB SHORTWAVES WILL MOVE ACROSS NORTHERN
IOWA...THE FIRST ON MONDAY AND THE SECOND ON TUESDAY MORNING. AT THE
SURFACE A HIGH PRESSURE RIDGE WILL CROSS THE AREA ON MONDAY...WITH
THE MID-LEVEL SHORTWAVE GENERATING CLOUDS BUT FORECAST SOUNDINGS
INDICATING TOO MUCH DRY AIR IN THE LOWER LEVELS TO RESULT IN
PRECIPITATION. ON MONDAY NIGHT HOWEVER THE RIDGE WILL MOVE OFF TO
THE EAST...AND A SURFACE LOW WILL DEVELOP AROUND THE BLACK HILLS
AHEAD OF THE APPROACHING SECOND WAVE AND MOVE QUICKLY EASTWARD
TOWARD IOWA. THIS WILL CAUSE SURFACE WINDS TO COME AROUND QUICKLY TO
SOUTH BY EARLY TUESDAY MORNING WITH AN INCREASE IN ATMOSPHERIC
MOISTURE. AS THE WAVE AND LOW CROSS THE AREA ON TUESDAY MORNING IT
WILL PROVIDE A BRIEF OPPORTUNITY FOR SOME LIGHT SNOW ACROSS OUR FAR
NORTH BEFORE THE SYSTEM CLEARS OUT RAPIDLY TO THE EAST. AT THIS TIME
WILL STICK WITH JUST SLIGHT POPS ROUGHLY NORTH OF HIGHWAY 20 ON
TUESDAY MORNING...AND LITTLE IF ANY ACCUMULATION IS ANTICIPATED.
THE BIGGEST POTENTIAL WEATHER IMPACT OF THE SEVEN DAY FORECAST WILL
COME FROM A LONGWAVE 500 MB TROUGH COMING ASHORE OVER THE PACIFIC
U.S. COAST LATE ON TUESDAY. IT STILL APPEARS THAT THIS TROUGH WILL
NOT BE FULLY PHASED...AND THAT MOST OF THE ENERGY WILL DIG INTO THE
SOUTHERN STREAM WITH A NORTHERN STREAM WAVE TRAILING SLIGHTLY
BEHIND. AS THE OVERALL SYSTEM MOVES EASTWARD TOWARD THE CENTRAL U.S.
AND IOWA THE COMPLICATED EVOLUTION OF THE TWO INTERTWINED WAVES WILL
HAVE DRAMATIC IMPACTS ON THE DETAILS OF THEIR ASSOCIATED SENSIBLE
WEATHER. THE SOUTHERN STREAM WAVE WILL GENERATE A STRONG SURFACE LOW
PRESSURE CENTER OVER THE SOUTHERN HIGH PLAINS ON TUESDAY NIGHT/EARLY
WEDNESDAY...WHICH WILL SUBSEQUENTLY MOVE EAST NORTHEAST ACROSS
MISSOURI AND ILLINOIS...WITH A LARGE SWATH OF SNOW SPREADING ALONG
THE NORTHWESTERN FLANK OF THE TRACK. HOWEVER THE PHASING
ISSUES...COMBINED WITH THE FACT THAT THE ENTIRE SYSTEM IS STILL WELL
OFFSHORE AND NOT BEING SAMPLED BY THE UPPER AIR NETWORK...ARE
WREAKING HAVOC WITH THE FORECAST OF THE STORM TRACK BEING OUTPUT BY
THE VARIOUS PROGNOSTIC MODELS. A SHIFT OF 50 OR 100 MILES ONE WAY OR
ANOTHER WILL MAKE THE DIFFERENCE BETWEEN THE HEAVIER SNOW SWATH
FALLING ACROSS CENTRAL IOWA...SOUTHEASTERN IOWA...OR NORTHEASTERN
MISSOURI. GIVEN THE INHERENT UNCERTAINTY IN THIS SCENARIO AND POOR
CONSISTENCY AMONG THE MODELS HAVE OPTED TO KEEP THE FORECAST VERY
CLOSE TO PREVIOUS ISSUANCES...WITH LIKELY TO CATEGORICAL POPS ACROSS
ABOUT THE SOUTHEASTERN HALF OR TWO THIRDS OF THE CWA. IT IS STILL
TOO EARLY TO MAKE ANY FORECAST OF SNOWFALL AMOUNTS...BUT SEVERAL
INCHES OF SNOWFALL ARE LIKELY TO THE NORTHWEST OF THE LOW AND
PROBABLY SOMEWHERE IN THE SOUTHEASTERN HALF OF OUR AREA. THIS WILL
BE CLOSELY MONITORED OVER THE NEXT SEVERAL DAYS.
THE MIDWEEK SYSTEM WILL CLEAR OUT QUICKLY LATE THURSDAY AND THURSDAY
NIGHT...AFTER WHICH QUIET AND DRY WEST NORTHWESTERLY 500 MB FLOW
WILL BE ESTABLISHED. THIS WILL LEAD TO COOLER WEATHER...ESPECIALLY
IF A SNOW PACK IS IN PLACE AFTER THE WEDNESDAY/THURSDAY STORM...WITH
NO ADDITIONAL PRECIPITATION IN THE FORECAST.
&&
.AVIATION...17/06Z
LIFR/IFR STRATUS HAS MOVED INTO THE NORTHERN TAF SITES AND IS
EXPECTED TO CONTINUE TO PROGRESS SOUTH TO SOUTHEASTWARD IN AREAS
ALONG AND NORTHEAST OF THE SFC HIGH AXIS. VSBYS EXPECTED TO CONTINUE
TO LOWER THROUGH THE NIGHT AS WELL BENEATH THE HIGH...WITH
POSSIBILITY OF LIFR/IFR VSBYS AS WELL. GREATEST CHANCES WILL BE AT
KMCW AND KFOD. WINDS WILL SHIFT AROUND TO THE NORTHEAST TO EAST
THROUGH MONDAY MORNING...AND THEN AROUND TO THE SOUTH TO SOUTHEAST
BY LATE MONDAY AFTERNOON INTO MONDAY EVENING AS THE SFC HIGH AXIS
MOVES THROUGH THE CWA. ONCE WINDS GO SOUTH...EXPECT CIGS TO SCOUR
OUT SOME WITH POSSIBLY MVFR/LOW VFR CIGS EXPECTED.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...ZOGG
LONG TERM...LEE
AVIATION...BEERENDS
UPDATE...BEERENDS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1015 PM CST SUN DEC 16 2012
.AVIATION...06Z KGRI TAF. LOW CLOUDS HAVE MOVED FURTHER EAST AND
MID CLOUDS HAVE MOVED IN FROM THE WEST. EXPECT IT WILL BE MORE
DIFFICULT NOW FOR THE LOW CLOUDS TO SPREAD BACK INTO KGRI GIVEN
RECENT MODEL RUNS THAT PUSH A SFC TROUGH THROUGH PRIOR TO DAWN
AND TURN THE SFC WINDS TO WESTERLY. THEREFORE...HAVE REMOVED TEMPO
GROUP THAT HAD INDICATED IFR CONDITIONS FOR THE HOURS AROUND DAWN.
BELIEVE THAT VFR CONDITIONS WILL PERSIST THROUGH THE TAF VALID
PERIOD.
&&
.PREV DISCUSSION... /ISSUED 900 PM CST SUN DEC 16 2012/
UPDATE...SNOW FLURRIES HAVE BEEN REPORTED WEST OF OUR CWA AND
EXPECT THESE WILL SLIDE ACROSS OUR FORECAST AREA OVER THE NEXT FEW
HOURS. ANY SNOW FLURRIES OR BRIEF LIGHT SNOW WILL LIKELY END
BEFORE DAWN. IR SATELLITE IMAGERY INDICATES COOLING CLOUD TOPS
THIS EVENING ACROSS SOUTH CENTRAL NEBRASKA AND FORECAST MODELS
SHOW A WEAK VORT MAX PRESSING EAST ACROSS THE REGION.
CONSEQUENTLY...DESPITE THE LACK OF MODEL QPF...BELIEVE THAT FLURRIES
WILL CONTINUE TO BE POSSIBLE WITH THIS UPPER TROUGH AS IT SLIDES
EAST TONIGHT.
PREV DISCUSSION... /ISSUED 337 PM CST SUN DEC 16 2012/
SHORT TERM...TONIGHT AND TOMORROW.
UPPER LEVEL SATELLITE DATA HAS SHOW A FEW SMALL DISTURBANCES
SHIFTING ACROSS THE PLAINS TODAY...ONE OF WHICH BROUGHT SOME LIGHT
SNOW TO PORTIONS OF THE CWA THIS MORNING. TRACE AMOUNTS UP NEAR
A HALF OF AN INCH WERE REPORTED...AND BY MIDDAY PRECIPITATION
TRENDS HAD FALLEN BACK TO JUST A FEW SCATTERED FLURRIES IN
NORTHEASTERN PORTIONS OF THE CWA. CLOUD COVER HAS BEEN
ANNOYING...THE NORTHEASTERN HALF OF THE CWA HAS BEEN STUCK UNDER
STUBBORN LOW LEVEL STRATUS...VS THE WESTERN HALF WHICH HAS SEEN
PLENTY OF SUN. SURFACE ANALYSIS SHOWS A RIDGE AXIS EXTENDING
THROUGH THE CENTRAL/EASTERN PORTIONS OF THE REGION...KEEPING WINDS
GENERALLY ON THE LIGHT AND AT TIMES VARIABLE SIDE. THANKS TO THE
CLOUD COVER...EASTERN LOCATIONS HAVE HUNG AROUND THE LOW 30S THIS
AFTERNOON...OUT WEST HAS REACHED INTO THE LOWER 40S.
KEPT THE FORECAST TONIGHT DRY...THOUGH MODELS ARE SHOWING ANOTHER
WEAK DISTURBANCE SWINGING THOUGH THE REGION...POTENTIALLY BRINGING
SOME ADDITIONAL LIGHT PRECIPITATION. AT THIS POINT...SHOULD ANY
PRECIPITATION FALL...IT LOOKS TO REMAIN JUST OFF TO THE
SOUTH/SOUTHWEST OF THE CWA. AT THE SURFACE...A WEAK TROUGH AXIS
GETS PUSHED THROUGH AS THE DISTURBANCE CROSSES...EVENTUALLY
BRINGING A WESTERLY COMPONENT TO THE WINDS. AHEAD OF THAT
SWITCH...CONCERNED ABOUT THE POTENTIAL FOR SOME PATCHY FOG
DEVELOPMENT...AS THE WINDS REMAIN LIGHT/CALM WITH NOT AS MUCH IN
THE WAY OF CLOUD COVER EXPECTED. WITH THE NAM/SREF BOTH SHOWING
REDUCED VISIBILITIES AND THE RAP NOT TOO FAR OUTSIDE THE CWA
BOUNDARY...DECIDED TO INSERT A PATCHY FOG MENTION ACROSS PORTIONS
OF SC NEB.
INTO MONDAY...EXPECTING TO SEE WEAK SHORTWAVE UPPER LEVEL RIDGING
OVER THE REGION...KEEPING CONDITIONS QUIET. SHOULD SEE VARIABLE
SKY COVER THROUGH THE DAY WITH UPPER LEVEL CLOUDS STREAMING IN.
AT THE SURFACE...THE CWA IS COMING UNDER INCREASING INFLUENCE OF
LOW PRESSURE DEVELOPING OVER THE HIGH PLAINS...RESULTING IN WINDS
BECOMING MORE SOUTHERLY WITH TIME. AFTER LOW TEMPERATURES TONIGHT
EXPECTED IN THE TEENS TO LOWER 20S...HIGHS ON MONDAY LOOK TO REACH
INTO THE LOWER 40S TO NEAR 50.
LONG TERM...MONDAY NIGHT THROUGH SUNDAY.
MAIN CHALLENGE REMAINS DETERMINING CHANCES AND TIMING OF SNOW FOR
WEDNESDAY/WEDNESDAY NIGHT.
WE BEGIN THE LONG TERM FORECAST MONDAY NIGHT WITH ZONAL FLOW. THE
FLOW REMAINS QUITE PROGRESSIVE AS A SIGNIFICANT TROUGH DEVELOPS IN
THE WESTERN UNITED STATES BY TUESDAY. AS A RESPONSE TO THIS
DEEPENING TROUGH TO THE WEST...PLENTY OF WARM AIR WILL ARRIVE ON
TUESDAY AND PLACE OUR HIGH TEMPERATURES WELL ABOVE NORMAL BY ABOUT
15 DEGREES OR SO. THIS ABOVE NORMAL WEATHER WILL MOST CERTAINLY
NOT LAST AS THE TROUGH PROGRESSES QUICKLY TO THE EAST AND AN
ASSOCIATED COLD FRONT SWINGS IN FROM THE NORTHWEST VERY LATE
TUESDAY NIGHT INTO WEDNESDAY. A SHARP COOL DOWN WILL ENSUE.
THE TIMELINE FOR THIS NEXT WAVE IS TRENDING TOWARD A SOONER ARRIVAL
AND SOONER EXIT. ISENTROPIC LIFT BEGINS EARLY WEDNESDAY MORNING
BEHIND A QUICKLY MOVING COLD FRONT...WITH THIS FORCING GIVING WAY
TO MID-LEVEL FRONTOGENETIC FORCING LATER IN THE DAY.
ALSO...LARGER SCALE SYNOPTIC FORCING BECOMES STRONGER AS THE DAY
WEARS ON AND IS FORECAST TO BE RESPECTABLE FOR A SHORT
TIME...ADDING ANOTHER LAYER OF FORCING TO AID IN SNOW PRODUCTION.
THE ECMWF INDICATES THAT SYNOPTIC FORCING WILL PEAK NEAR 00Z
THURSDAY. THIS WAVE IS A QUICK HITTER...HOWEVER...WITH MOST IF NOT
ALL FORCING EAST OF THE CWA BY MIDNIGHT WEDNESDAY NIGHT...WHICH
WILL ALSO END ANY SNOW PRODUCTION. WITH THIS WAVE BEING SUCH A
QUICK HITTER...SNOW AMOUNTS ARE STILL ON TRACK FOR UP TO 4 INCHES
OR SO FOR SOMEBODY NEARBY...BUT THIS PROBABLY WOULD NOT BE A
UBIQUITOUS SNOW AMOUNT. IF THIS SYSTEM SLOWS DOWN JUST A
BIT...THIS COULD MEAN MORE SNOW WITH LARGER SNOW AMOUNTS AND
PLENTY OF WIND TO CREATE DRIFTING SNOW POTENTIAL. WIND ALOFT FOR
WEDNESDAY AFTERNOON AND EVENING IS QUITE STRONG AND BLOWING SNOW
WILL BE A POTENTIAL ISSUE. THERE IS ALSO SOME DISCREPANCY AMONG
MODELS WHERE THE TRACK OF THE 700 MB CLOSED LOW WILL BE AS THE NAM
DRAGS THIS LOW ACROSS THE CENTRAL CWA...WHILE THE ECMWF TAKES THE
700 MB LOW ACROSS CENTRAL KANSAS. THE GFS DOES NOT CLOSE THE LOW
OFF...BUT DOES FAVOR A SOLUTION CLOSER TO THE ECMWF. NO QUESTION
ABOUT PRECIPITATION TYPE SO FAR...AS SOUNDINGS INDICATE ALL SNOW
WITH THIS EVENT. WE TEND TO FAVOR A MORE SOUTHERN TRACK WITH THESE
PACIFIC SYSTEMS. ALSO WEDNESDAY MAY BE A TRICKY DAY FOR HOURLY
TEMPERATURES DEPENDING ON THE TIMING OF THE COLD FRONT. WE COULD
REACH HIGHS MORE TOWARD LATE MORNING RATHER THEN IN THE AFTERNOON.
ANYWAY...TEMPERATURES WILL PROBABLY GO ALMOST NOWHERE FROM THE
LOWS ON TUESDAY NIGHT. I CONTINUED TO GO COLDER THAN ALLBLEND FOR
TEMPERATURES FOR WEDNESDAY NIGHT AND BEYOND CONSIDERING POTENTIAL
SNOW COVER.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
448 AM EST MON DEC 17 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE NORTHEAST ACROSS THE REGION THIS AFTERNOON
AND EVENING. HIGH PRESSURE WILL BUILD IN TUESDAY AND WEDNESDAY. A
STRONG COLD FRONT WILL SWEEP THROUGH THE AREA ON THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
WEAK COLD FRONT LIES A BIT NORTHWEST OF I-71 EARLY THIS MORNING.
THIS MAY CONTINUE TO SAG A BIT FURTHER SOUTH THROUGH THE MORNING.
SHOWERS HAVE BEEN OCCURRING TO THE SOUTH OF THE FRONT THROUGH MUCH
OF THE NIGHT. SHORT RANGE GUIDANCE SUGGESTS THAT THERE COULD BE A
BREAK IN THIS ACTIVITY AROUND DAYBREAK. BUT MORE SHOWERS WILL
SPREAD IN FROM THE SOUTHWEST AS A WAVE OF LOW PRESSURE TRACKS
ALONG THE FRONT.
APPEARS THAT THIS INITIAL WAVE WILL TAKE WIDESPREAD SHOWERS ACROSS
THE SOUTHEAST HALF OF THE AREA THROUGH EARLY AFTERNOON. ONCE AGAIN
THERE COULD BE A LULL IN ACTIVITY BEFORE MAIN SURFACE LOW
APPROACHES LATER IN THE DAY.
EXPECT THIS LOW TO TRACK A BIT FURTHER NORTH THAN THE INITIAL
WAVE. THUS SHOWERS WILL OCCUR ACROSS A GREATER PART OF THE
FORECAST AREA. SHOWERS WILL CONTINUE INTO THE EVENING BEFORE
TAPERING OFF LATER TONIGHT.
INSTABILITY WILL DEVELOP INTO THE SOUTHERN PORTION OF THE FORECAST
AREA THIS AFTERNOON AND EVENING. THUS SOME THUNDERSTORMS ARE
POSSIBLE. FORECAST SOUNDINGS FROM THE 00Z/06Z NAM DO NOT LOOK TOO
IMPRESSIVE. BUT LATEST RAP RUNS MANAGE A BIT MORE INSTABILITY.
CANNOT RULE OUT A FEW STRONGER STORMS MAINLY TO THE SOUTH OF
CINCINNATI LATE THIS AFTERNOON AND EARLY THIS EVENING.
CONCERNED THAT CLOUDS AND OCCASIONAL PRECIPITATION WILL LIMIT
TEMPERATURES. SO HAVE MOSTLY SHADED ON THE COOL SIDE OF GUIDANCE
FOR HIGHS. MOS LOOKED IN THE BALL PARK FOR LOWS.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
COULD BE A FEW LINGERING SHOWERS IN THE FAR EASTERN COUNTIES TO
START TUESDAY. BUT THE MAIN TREND WILL BE FOR HIGH PRESSURE TO
BUILD IN DURING THE PERIOD. A WEAK LOW WILL PASS ACROSS THE GREAT
LAKES TUESDAY NIGHT WHICH WILL TEMPORARILY SUPPRESS THE HIGH
SOMEWHAT. BUT THIS SHOULD ONLY BRING SOME CLOUDS TO THE NORTHERN
COUNTIES.
STAYED SLIGHTLY BELOW MOS FOR TUESDAY HIGHS. OTHERWISE A MOS BLEND
LOOKED REASONABLE FOR TEMPERATURES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A VIGOROUS SHORT WAVE WILL PIVOT NORTHEAST THROUGH THE REGION
DURING THE EARLY PART OF THE PERIOD. THIS WILL TAKE A DEEPENING
SURFACE LOW TO THE NORTHWEST OF THE FORECAST AREA. BUT A TRAILING
STRONG COLD FRONT WILL CROSS THE AREA ON THURSDAY. THERE ARE STILL
SOME SLIGHT TIMING DISCREPANCIES WITH THIS. HAVE GONE TOWARDS THE
SLIGHTLY SLOWER 00Z ECMWF WHICH HAS SUPPORT FROM THE 00Z CANADIAN.
SHOWERS WILL BE WIDESPREAD AHEAD OF THIS SYSTEM. THEY WILL SPREAD
INTO THE WESTERN COUNTIES LATE WEDNESDAY NIGHT AND MOVE ACROSS THE
ENTIRE AREA ON THURSDAY. TEMPERATURES WILL BE NON-DIURNAL. DO
EXPECT SOME DROP OFF IN READINGS WEDNESDAY EVENING BEFORE STARTING
TO RISE LATER IN THE NIGHT. TEMPERATURES WILL SHARPLY DROP AFTER
THE FRONTAL PASSAGE THURSDAY AFTERNOON. MODELS STILL NOT
DEVELOPING MUCH INSTABILITY WITH THIS. BUT WILL HAVE TO WATCH FOR
THUNDER POTENTIAL GIVEN STRONG DYNAMICS.
EXPECT WRAP AROUND SNOW SHOWERS WITH A BRIEF WINDOW FORM SOME LAKE
ENHANCEMENT THURSDAY NIGHT INTO FRIDAY. IN ADDITION...COLD
ADVECTION AND A STRONG PRESSURE GRADIENT WILL RESULT IN BLUSTERY
WINDS FROM AFTER FRONTAL PASSAGE RIGHT INTO FRIDAY. AS THE ENTIRE
SYSTEM LIFTS FURTHER AWAY FROM THE REGION THE WINDS WILL SUBSIDE
AND THE CHANCE OF SNOW SHOWERS WILL DIMINISH.
COLD HIGH PRESSURE CENTERED OVER THE UPPER MIDWEST WILL RIDGE
SOUTHEAST INTO THE REGION FOR THE WEEKEND. TEMPERATURES WILL BE AT
OR BELOW NORMAL FROM THURSDAY NIGHT THROUGH SUNDAY.
&&
.AVIATION /09Z MONDAY THROUGH FRIDAY/...
A FRONTAL BOUNDARY IS CURRENTLY LOCATED NEAR A LINE FROM KCVG TO
KLCK. AN AREA OF LOW PRESSURE WILL APPROACH THE AREA ON MONDAY
ENHANCING SHOWER ACTIVITY ALONG AND TO THE SE OF THIS BOUNDARY.
THIS AREA OF LOW PRESSURE WILL MOVE OUT OF THE AREA MONDAY NIGHT
AND DRY CONDITIONS WILL BEGIN TO RETURN TO THE TAF SITES BY THE
END OF THE TAF PERIOD. THE BEST INSTABILITY STAYS SOUTH OF THE TAF
SITES AND THEREFORE LEFT THUNDER OUT OF THE TAFS AT THIS TIME.
MVFR CIGS AND VSBYS WILL GRADUALLY DEVELOP ACROSS THE TAF SITES BY
MORNING AND REMAIN ACROSS THE AREA FOR MONDAY. SOME LOCATIONS MAY
ALSO BRIEFLY SEE IFR OR LIFR VSBYS OVERNIGHT AND INTO THE EARLY
MORNING DAYTIME HOURS.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES WILL BE POSSIBLE FROM
MONDAY NIGHT THROUGH TUESDAY. MVFR CONDITIONS ARE AGAIN EXPECTED ON
THURSDAY. STRONG WINDS ARE LIKELY THURSDAY AFTERNOON AND NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...NOVAK
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
118 AM EST MON DEC 17 2012
.SYNOPSIS...
A WEAK COLD FRONTAL BOUNDARY LOCATED SOUTHEAST OF THE I-71
CORRIDOR WILL SEE LOW PRESSURE MOVE TO THE NORTHEAST ALONG IT ON
MONDAY. THIS WILL COMBINE WITH AN EASTWARD MOVING UPPER LEVEL
TROUGH TO INITIATE SHOWERS AND POSSIBLY SOME THUNDERSTORMS. HIGH
PRESSURE WILL BUILD SOUTH OF THE OHIO VALLEY THROUGH THE MIDDLE OF
THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
17.00Z KILN SOUNDING CAME IN WITH MINUSCULE INSTBY...WITH < 100
J/KG MUCAPE BUT A SOMEWHAT DECENT MID-LEVEL LAPSE RATE IN EXCESS
OF 7 C/KM. MID EVENING WATER VAPOR IMAGERY CONTINUES TO DEPICT A
SHORTWAVE MOVING THROUGH IL TOWARD OH BUT SEEMS TO BE SHEARING
OUT/DEAMPLIFYING A BIT. LAST FEW SETS OF RAP DATA HAVE REALLY
BACKED OFF ON DEGREE OF FORCING WITH THIS WAVE AND HAVE DECREASED
LOW LEVEL JET FOCUS INTO THE WEAK FRONTAL BOUNDARY SAGGING
THROUGH WRN OH. THE RESULT OVER THE LAST FEW HOURS...IS A
SMALLER/LIGHTER QPF FIELD IN THE RAP OVER VERSIONS LOOKED AT
THROUGH THE AFTERNOON. EXPERIMENTAL HRRR HAS SEEN SOME
OUTAGES...BUT LAST AVAILABLE RUN /22Z/ STILL SHOWED A RATHER
HEALTHY BATCH OF SHOWERS DEVELOPING TO THE SW OF CVG AND MOVING
ACROSS OUR SRN/SERN AREAS. THE NEW 17.21 SREF PROBS FOR MEASURABLE
PRECIPITATION HAVE DECREASED MARKEDLY AS WELL FROM 17.15Z VALUES.
ALL IN ALL...WILL MAINTAIN CURRENT AXIS OF RAIN CHANCES BEGINNING
IN NEXT COUPLE OF HOURS ACROSS FAR SRN FORECAST AREA...AND PEAKING
IN THE HOURS AFTER MIDNIGHT FROM SOUTH OF CVG EAST/NORTHEAST INTO
SCNTL OH. BUT HAVE DECREASED CHANCES A BIT FROM PREVIOUS
UPDATE. STILL HAVE A LITTLE THUNDER IN THE GRIDS...BUT BASED ON
THE KILN SOUNDING LIGHTNING IS GOING TO BE TOUGH TO COME BY WITH
EQUILIBRIUM LEVEL TEMPS BARELY TO -20C AND SUCH MEAGER INSTBY.
WITH CLEARING OF HIGH CLOUDS IN THE WEST FOR A FEW HOURS THIS
EVENING...THIS ALLOWED A LOCAL TEMP DROP MORE THAN I HAD PREVIOUS
ANTICIPATED AND THUS HAVE DROPPED MIN TEMPS IN THE WESTERN 1/3RD
OF THE FORECAST AREA. A LITTLE FOG COULD FORM IN THIS AREA BUT IT
APPEARS PER SATELLITE IMAGERY THAT LOW CLOUDS ARE QUICKLY
REDEVELOPING IN THE MOIST ADVECTION SPOKE OF PREVIOUSLY. IT
WOULDN/T TAKE LONG FOR DENSE FOG TO FORM IN THIS NARROW CLEAR SLOT
BETWEEN THE LOW CLOUDS LAGGING THE WEAK COLD FRONT...AND THE THICK
CIRRUS MOVING EAST THROUGH THE AREA. WILL MONITOR.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/...
WEAK SURFACE FORCING WITH THE NEWD MOVING LOW WILL COMBINE WITH
THE UPWARD MOTION AND VORTICITY MAXIMA AHEAD OF THE UPPER LEVEL
TROUGH TO SPARK ACTIVITY LATE TONIGHT AND MORESO TOMORROW.
UNFORTUNATELY THE SHOWERS SHOULD INITIATE ALONG THE MOISTURE
CONVERGENCE AXIS WHICH IS HARD TO PLACE. BEST ESTIMATES RUN ALONG
THE OHIO RIVER SOUTHWEST OF CINCINNATI...THEN JOG NORTHEAST TO
COLUMBUS. THE LOW LEVEL FORCING WITH THE SURFACE TROUGH IS WELL
AHEAD OF THE STRONGER UPPER LEVEL FORCING WITH THE MID LEVEL
SHORTWAVE...WHICH WILL GIVE A PROLONGED POTENTIAL FOR SHOWER
ACTIVITY BUT NOT A CLEAR CUT INDICATION OF THE
HEAVIEST/STRONGEST/MOST LIKELY PLACEMENT OF THE RAIN. BY DAYBREAK
TUESDAY...THE SURFACE LOW IS WELL EAST OF THE REGION AND THE UPPER
LOW IS EXITING OHIO. ANY RAIN WILL HAVE ENDED OVERNIGHT MONDAY.
TEMPERATURES REMAIN UNSEASONABLY WARM BUT ALL OF THE GUIDANCE WERE
PEGGED WITHIN A FEW DEGREES OF EACH OTHER AND NO SIGNIFICANT
CHANGES WERE MADE HERE. CLOUD COVER WILL BE ON THE DECREASE
TUESDAY BUT ASIDE FROM THIS...IT SHOULD BE A RELATIVELY CLOUDY AND
MILD PERIOD...PARTICULARLY FOR MID DECEMBER.
SPC HAS THUNDERSTORMS OVER THE REGION WITH A SLIGHT CHANCE OF
SEVERE NOTED FOR MUCH OF KENTUCKY. WITH THE DISJOINTED NATURE OF
THE SURFACE AND UPPER FORCING...NO CLEAR CUT STRONG VORT
MAXIMA...AND SIGNIFICANT CLOUD COVER EXPECTED...I DID NOT FEEL THE
NECESSARY INGREDIENTS FOR PARTICULARLY STRONG STORMS WERE PRESENT.
THE THUNDER FORECAST I USED TOOK 12Z NAM CAPES OVER 200 AND ADDED
THEM WHERE RAIN CHANCE WAS GREATER THAN 30...YIELDING A NARROW
SWATH SOUTHEAST OF THE I-71 CORRIDOR LATER TONIGHT AND THEN
GENERALLY OVERSPREADING KY EARLY TOMORROW.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
OPERATIONAL MODELS WERE COMING INTO A BETTER AGREEMENT FOR THE NEXT
WEATHER MAKER TO AFFECT THE AREA THURSDAY INTO FRIDAY. HAVE USED A
BLEND OF THE OPERATIONAL 16.12Z GFS AND THE 16.00Z ECMWF.
THE LONG TERM WILL START OUT QUIET ON WEDNESDAY AS MID LEVEL RIDGING
WILL BE IN PLACE ACROSS THE OHIO VALLEY OUT AHEAD OF AFOREMENTIONED
WEATHER SYSTEM DEVELOPING ACROSS THE SRN PLAINS. CLOUDS WILL
INCREASE THROUGH THE DAY...BUT WE SHOULD AT LEAST SEE PARTLY TO
MOSTLY SUNNY SKIES EARLY ON. HIGH TEMPERATURES WILL CONTINUE TO BE
ABOVE NORMAL...RANGING FROM THE LOWER 50S NORTH TO THE UPPER 50S
SOUTH.
FOR THE PERIOD WEDNESDAY NIGHT INTO THURSDAY NIGHT...A DEEPENING MID
LEVEL TROF AND DEEPENING SFC LOW PRESSURE SYSTEM WILL PULL NORTHEAST
FROM THE SRN PLAINS TO THE GREAT LAKES/OHIO VALLEY REGION. THE TRACK
OF THE SFC LOW CONTINUES TO BE NW OF THE REGION...SO ANY MAJOR
WINTER WEATHER WILL STAY WELL TO OUR NW. THE LOW WILL BE ASSOCIATED
WITH A STRONG COLD FRONT. DEEP MOISTURE COMBINED WITH STRONG
SYNOPTIC SCALE FORCING WILL SPREAD SHOWERS INTO THE REGION WEDNESDAY
NIGHT AND WILL CONTINUE INTO THURSDAY. PCPN SHOULD TAPER OFF SOME
BEHIND FRONTAL PASSAGE. TEMPERATURES WILL WARM INTO THE LOWER AND MID
50S ON THURSDAY FOLLOWED BY FALLING TEMPERATURES LATE IN THE DAY
INTO THURSDAY NIGHT. COLD AIR ADVECTION IN THE WAKE OF THE LOW AND
FRONT WILL BRING SOME WRAP AROUND AND LAKE INDUCED SNOW SHOWERS LATE
THURSDAY INTO THURSDAY NIGHT. RIGHT NOW...ANY SNOW ACCUMULATION
SHOULD BE MINOR. WINDY CONDITIONS ARE FORECAST DUE TO A TIGHTENING
PRESSURE GRADIENT AND MOMENTUM TRANSFER IN THE STRONG COLD AIR
ADVECTION BEHIND FRONTAL PASSAGE THURSDAY INTO THURSDAY NIGHT. SO
WILL MENTION THIS POTENTIAL HAZARD IN THE HWO PRODUCT.
FOR FRIDAY INTO FRIDAY NIGHT...UPR LVL TROF WILL HAVE CLOSED OFF TO
OUR NORTH AND NORTHEAST...AND WILL QUICKLY MOVE AWAY FROM OUR
REGION. CLOUDS AND LINGERING SNOW SHOWERS ON FRIDAY WILL TAPER OFF
FROM SW TO NE THROUGH THE DAY...FOLLOWED BY CLEARING SKIES FRIDAY
NIGHT. THE COLDEST TEMPERATURES OF THE WEEK APPEAR TO BE ON FRIDAY
WITH HIGHS STRUGGLING TO WARM INTO THE LOWER AND MID 30S.
FOR SATURDAY INTO SUNDAY...UPR LVL CLOSED LOW IS EXPECTED TO ROTATE
NORTHEASTWARD WHILE OUR REGION STAYS IN A NORTHWEST FLOW ALOFT ALONG
WITH HIGH PRESSURE AT THE SURFACE. DRY WEATHER ALONG WITH NEAR
SEASONAL TEMPERATURES WILL BE FORECAST ATTM.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
A FRONTAL BOUNDARY IS CURRENTLY LOCATED NEAR A LINE FROM KCVG TO
KLCK. AN AREA OF LOW PRESSURE WILL APPROACH THE AREA ON MONDAY
ENHANCING SHOWER ACTIVITY ALONG AND TO THE SE OF THIS BOUNDARY.
THIS AREA OF LOW PRESSURE WILL MOVE OUT OF THE AREA MONDAY NIGHT
AND DRY CONDITIONS WILL BEGIN TO RETURN TO THE TAF SITES BY THE
END OF THE TAF PERIOD. THE BEST INSTABILITY STAYS SOUTH OF THE TAF
SITES AND THEREFORE LEFT THUNDER OUT OF THE TAFS AT THIS TIME.
MVFR CIGS AND VSBYS WILL GRADUALLY DEVELOP ACROSS THE TAF SITES BY
MORNING AND REMAIN ACROSS THE AREA FOR MONDAY. SOME LOCATIONS MAY
ALSO BRIEFLY SEE IFR OR LIFR VSBYS OVERNIGHT AND INTO THE EARLY
MORNING DAYTIME HOURS.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES WILL BE POSSIBLE FROM
MONDAY NIGHT THROUGH TUESDAY. MVFR CONDITIONS ARE AGAIN EXPECTED ON
THURSDAY. STRONG WINDS ARE LIKELY THURSDAY AFTERNOON AND NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...BINAU
SHORT TERM...FRANKS
LONG TERM...HICKMAN
AVIATION...NOVAK
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1115 PM CST SUN DEC 16 2012
.UPDATE...FOR 06Z AVIATION FORECAST
&&
.AVIATION...
BEGINNING TO SEE A LITTLE BIT OF LIGHT RAIN BREAKING OUT AROUND
MEMPHIS AT 0415Z AS SREF NOW SHOWING UPPER TROUGH THAT IS BACK
OVER SOUTHERN PLAINS BEGINNING TO MOVE THIS WAY. LATEST RUC RUN
DEVELOPS THIS ACTIVITY OVER WESTERN TENNESSEE...NORTHERN
MISSISSIPPI AND FAR WESTERN KENTUCKY THROUGH ABOUT 07Z THEN WORKS
IT NORTHEASTWARD AND INTO WESTERN MIDDLE TENNESSEE AFTER 07Z AND
INTO THE NASHVILLE AREA AROUND 09Z AND CONTINUE TO OVERSPREAD
MIDDLE TENNESSEE DURING THE LATE NIGHT. THIS ACTIVITY IS ALIGNED
PRETTY MUCH WITH THE 70 KNOT MID-LEVEL JET THAT RUNS SOUTHWEST TO
NORTHEAST AND OUT AHEAD OF A NOW STATIONARY FRONTAL BOUNDARY
DRAPED ALONG THE OHIO RIVER DOWN THROUGH POPLAR BLUFF MISSOURI TO
ABOUT TEXARKANA AT 04Z. FRONTAL BOUNDARY NOT PROGGED TO MOVE MUCH
IN THE OVERNIGHT. SELS HAS MID STATE OUTLOOKED FOR THUNDERSTORMS
ON MONDAY WITH GOOD PART OF THE MID STATE UNDER A SLIGHT RISK FOR
SEVERE. A GOOD SHOT OF POSITIVE VORTICITY WILL MOVE INTO THE MID
STATE FROM THE SOUTHWEST AROUND 14Z THROUGH 20Z ON MONDAY. BEST
CHANCE FOR THE STRONGER STORMS WOULD BE LATE MORNING THROUGH THE
AFTERNOON. BELIEVE BEST CHANCE FOR SEVERE WOULD BE EASTERN
AREAS/PLATEAU.
BOYD
&&
.PREV DISCUSSION... /ISSUED 852 PM CST SUN DEC 16 2012/
UPDATE...
LATEST RADAR IMAGERY INDICATES RAIN HAS EXITED THE FORECAST AREA
THIS EVENING...WHILE SATELLITE IMAGERY SHOWS MID/UPPER LEVEL
CLOUDS RAPIDLY SHIFTING EASTWARD AS SHORTWAVE EXITS THE REGION.
HOWEVER...LOW CLOUDS CAN BE SEEN RAPIDLY FORMING OVER WEST
TN...AND ALL MODEL GUIDANCE INDICATES REDEVELOPMENT OF SHOWERS
OVERNIGHT FROM WEST TN INTO WESTERN PARTS OF THE MID STATE. HAVE
ADJUSTED POPS TO SHOW ONLY SLIGHT CHANCE THROUGH MIDNIGHT...BUT
INCREASE TO CHANCE/LIKELY AFTERWARDS AS THE NEXT SHORTWAVE
APPROACHES AND SPAWNS NEW ACTIVITY TOWARDS SUNRISE. TWEAKED LOW
TEMPS AND SKY COVER FOR TONIGHT BASED ON LATEST TRENDS...BUT REST
OF FORECAST GENERALLY ON TRACK.
PREV DISCUSSION... /ISSUED 604 PM CST SUN DEC 16 2012/
UPDATE...FOR 00Z AVIATION FORECAST
AVIATION...
GOOD SURFACE PRESSURE GRADIENT ACROSS MIDDLE TENNESSEE WITH STRONG
PRESSURE FALLS NOW OCCURRING OVER THE WEST HALF WITH GUSTS TO 37
MPH AT BNA MOMENTS AGO. LOOK FOR WIND GUSTS ON THE ORDER OF 30 TO
35 KNOTS TO CONTINUE FOR THE NEXT HOUR OR TWO AS BACK EDGE OF RAIN
SHIELD PULLS EAST AND 80+ KNOT MID LEVEL JET PUNCHES UP THROUGH
MIDDLE TENNESSEE. LOOKS LIKE SHORT WAVE WILL WORK EASTWARD AND
EXIT MID STATE BY AROUND 03Z. I EXPECT IT WILL TAKE THE RAIN AREA
WITH IT AS IT MOVES INTO EASTERN TENNESSEE BY 03Z THIS EVENING.
ANOTHER SHORT WAVE MORE IN LINE WITH BROADER UPPER TROUGH ENERGY TO
OUR WEST WILL HEAD THIS WAY AFTER 06Z TONIGHT SO WILL HAVE AT
LEAST A MENTION OF SCATTERED SHOWERS IN THE OVERNIGHT BUT TIMING
UNCERTAIN AND CONFIDENCE LOW.
MUCAPES CLIMB > 500 J/KG DURING THE DAY MONDAY ACROSS MIDDLE
TENNESSEE SO AM EXPECTING SCATTERED THUNDERSTORMS FROM ABOUT 15Z
TO 22Z. BEST TIMING FOR FROPA BASED ON WIND SHIFT LINE WILL BE
LATE AFTERNOON AT CKV...EARLY EVENING AT BNA AND TOWARDS MIDNIGHT
MONDAY NIGHT AT CSV.
BOYD
PREV DISCUSSION... /ISSUED 310 PM CST SUN DEC 16 2012/
DISCUSSION...SFC FRONT IS STILL LOCATED WELL TO THE NW OVER THE
MID MS VALLEY BETWEEN PADUCAH AND ST LOUIS. HOWEVER...THERE IS A
SFC TEMPERATURE DISCONTINUITY OVER THE DEEP SOUTH...OVER SERN
LA...SERN MS...CNTRL AL AND CNTRL GA. ALOFT...A LARGE UPPER TROUGH
IS LOCATED OVER THE LEE OF THE ROCKIES WITH STRONG SWLY FLOW OVER
THE MS/OH VALLEYS. ONE THING...LOOKING AT LIGHTNING DATA...NUMBER
OF LIGHTNING STRIKES HAS DECLINED SIGNIFICANTLY OVER THE DEEP SOUTH
WITH FEWER THAN 5 STRIKES IN RECENT IMAGES.
UPPER TROUGH SLOWLY TRANSLATES EWD GENERATING A SFC LOW ON THE END
OF THE FRONT OVER TX WHICH PUSHES NEWD ACROSS THE MID SOUTH ON MON.
AFTER THE LOW PASSES...BRIEF WLY FLOW FROM A HIGH PRESSURE RIDGE
OVER THE GULF COAST COVERS THE AREA. LOW LEVEL FLOW QUICKLY COMES
BACK TO SLY ON TUE NGT AS A MAJOR UPPER TROUGH PLOWS THROUGH THE
PLAINS ON WED NGT. THE ASSOCD STRONG SFC LOW AND FRONT CROSSES THE
OH/TN VALLEYS ON THU BRINGING ADDITIONAL RAINFALL FOR WED NGT AND
THU.
THE FRONT PASSES ON TO THE EAST WITH A DECENT SHOT OF COLD AIR
OVER THE STATE FROM THU PM THROUGH FRI DROPPING AFTERNOON LOWS
INTO INTO THE 45-50 RANGE AND NIGHTIME LOWS INTO THE 25-30 RANGE.
GOOD WEATHER FOR THE WEEKEND WITH TEMPS A LITTLE ABOVE NORMAL.
SPC HAS OUTLOOKED SLIGHT RISK SEVERE FOR MUCH OF THE ERN HALF OF
THE MIDSTATE. PROGS SHOW INSTABILITY INCREASING SIGNIFICANTLY BY
MIDDAY WITH SIGNIFICANT 0-3 KM SHEAR.
HPC IS PREDICTING 0.1 TO 0.5 INCHES OF ADDITIONAL RAINFALL WITH
THE CURRENT SYSTEM AND ANOTHER .25 TO .75 INCHES FOR THE SYSTEM ON
WED NGT/THU.
FINALLY...THE CPC FOLKS SHOW NEAR NORMAL TEMPS FOR THE 6-14 DAY
PERIOD BUT ABOVE NORMAL RAINFALL.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
01
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
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
329 AM CST MON DEC 17 2012
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
329 AM CST MON DEC 17 2012
THE MAIN FOCUS FOR THE EARLY PORTION OF THE WEEK IS WITH THE
POTENTIAL FOR LIGHT SNOW ON TUESDAY FOLLOWED BY THE BEGINNING OF A
POSSIBLE WINTER STORM ON WEDNESDAY NIGHT.
CURRENTLY...EXTENSIVE CLOUD COVER REACHES FROM THE GREAT LAKES
THROUGH THE UPPER MISSISSIPPI RIVER VALLEY TO THE DAKOTAS BEFORE
CLEARING TO THE SOUTHWEST ALONG A WARM FRONT THAT EXTENDS FROM A
LOW IN FAR SOUTHEAST MONTANA THROUGH CENTRAL NEBRASKA. WINDS WILL
BE OUT OF THE NORTHWEST THROUGH MUCH OF TODAY WITH A SURFACE LOW
IN THE CENTRAL GREAT LAKES AND A RIDGE OF HIGH PRESSURE MOVING
ACROSS MINNESOTA. 17.00Z NAM/GFS AND 17.06Z RAP SOUNDINGS SHOW A
PERSISTENTLY STRONG INVERSION CENTERED ON 900MB THAT SHOULD KEEP
THE LOW LEVEL MOISTURE TRAPPED UNDERNEATH IT THROUGH THE DAY AND
SKIES ON THE CLOUDIER SIDE. THE SATURATED PORTION OF THIS PROFILE
DOES DIP DOWN TO AROUND -10C...SO THERE COULD BE SOME ICE THAT
DEVELOPS IF ANY LOW LEVEL LIFT CAN HELP TO PRODUCE SOME FLURRIES.
SOME RADAR RETURNS AND SURFACE OBS ARE REPORTING -SN OUT IN THE
SIOUX FALLS AREA CLOSER TO A WEAKENING AREA OF LOW PRESSURE...BUT
AM EXPECTING THAT AS THIS LOW TRIES TO RUN INTO THE RIDGE THAT IT
SHOULD LOSE MUCH OF ITS LOW LEVEL LIFT AND THAT THERE WONT BE MUCH
LEFT TO IT AS IT APPROACHES THE AREA.
A WEAK MID LEVEL SHORT WAVE TROUGH BREAKS TO THE EAST OF A CLOSED
LOW CURRENTLY IN THE PACIFIC NORTHWEST AND HELPS TO FORM AN
ELONGATED WEST TO EAST TROUGH THAT EXTENDS FROM THE DAKOTAS INTO
THE GREAT LAKES LATE TONIGHT INTO TOMORROW. THIS FEATURE WILL
PRODUCE SOME SLIGHTLY BETTER MID LEVEL LIFT THAT WILL BE AIDED BY
A PAIR OF SURFACE LOWS THAT WILL PROPAGATE EAST ALONG WITH IT. THE
NORTHERN SURFACE LOW WILL STICK TO THE DAKOTAS...BUT A SOUTHERN
LOW IS FORECAST TO TRACK ACROSS NORTHERN IOWA INTO SOUTHERN
WISCONSIN ON TUESDAY AND SHOULD PROVIDE SOME BETTER LIFT TO
DEVELOP A BAND OF PRECIPITATION TO THE NORTHEAST SIDE OF IT. THE
QG FORCING FROM THE MID LEVEL TROUGH APPEARS TO BE SLIGHTLY OFF
TIMING-WISE FROM THE LOW LEVEL FRONTOGENESIS TO WHERE THE
FORCING/MOISTURE IS NOT PARTICULARLY DEEP. THIS IS LIKELY WHY QPF
AMOUNTS ARE NOT MORE THAN A FEW HUNDREDTHS OF AN INCH WITH THIS
SYSTEM. SNOWFALL TOTALS WILL LIKELY BE SOMEWHERE IN THE HALF INCH
TO INCH RANGE WITH THE HIGHER TOTALS MORE LIKELY ACROSS SOUTHEAST
MINNESOTA AND WEST CENTRAL WISCONSIN WHERE THE PRECIPITATION TYPE
WILL REMAIN SNOW THROUGH THE DAY WHILE SOME RAIN COULD MIX IN
ACROSS NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN. THE DENDRITIC
GROWTH ZONE REMAINS FAIRLY SMALL AT LESS THAN A 100MB THROUGHOUT
THE DAY...SO AM NOT EXPECTING VERY HIGH SNOW TO LIQUID RATIOS FOR
THIS EVENT.
SKIES SHOULD CLEAR OUT TUESDAY NIGHT AS THE FRONT/TROUGH MOVES
THROUGH AND A RIDGE OF HIGH PRESSURE PUSHES IN FROM THE WEST. THIS
WILL SET THE STAGE FOR THE INITIAL STAGES OF A WINTER STORM THAT
WILL LIKELY AFFECT SOME OR ALL OF THE REGION. THE INITIAL BAND OF
PRECIPITATION WILL DEVELOP WEDNESDAY AFTERNOON ACROSS IOWA DUE TO
STRONG LOW LEVEL FRONTOGENETIC FORCING AS THE MAIN MID LEVEL
TROUGH ENTERS THE SOUTHERN PLAINS AND THE SURFACE LOW STARTS TO
DEEPEN IN THE SOUTHERN PLAINS. SOME DIFFERENCES ALREADY START TO
ARISE WEDNESDAY AFTERNOON BETWEEN THE 17.00Z MODEL RUNS WITH THE
ECMWF BEING THE SLOWEST TO BRING THE FRONTOGENETIC BAND INTO IOWA
WHILE THE GFS STRETCHES QPF ALL THE WAY INTO SOUTHWEST MICHIGAN.
THE NAM SHOWS A DRIER SOLUTION THAN WHAT THE GFS IS ADVERTISING
AND IS FURTHER TO THE WEST TO START OUT ON WEDNESDAY AFTERNOON.
WENT MAINLY WITH A 17.00Z GFS/ECMWF BLEND OVER THIS PERIOD AND
KEPT THE PRECIPITATION CHANCES MAINLY IN NORTHEAST IOWA. THE MID
LEVEL TROUGH THEN BEGINS TO CLOSE OFF WEDNESDAY NIGHT WITH THE
SURFACE LOW DEEPENING. THE OVERALL RESULT OF WHAT THE 17.00Z...AND
MANY PREVIOUS RUNS...PRODUCE IS A MAJOR WINTER STORM THAT MOVES
THROUGH THE GREAT LAKES REGION. THE QUESTION AT THIS POINT IS
WHERE THE CORE OF THE TROUGH/SURFACE LOW WILL TRACK.
TO START OUT...THE 17.00Z AND 17.06Z NAM ARE WARM/DEEP OUTLIERS IN
COMPARISON TO THE 17.00Z AND PREVIOUS RUNS OF THE ECMWF/GFS/GEM WITH
TAKING THE SURFACE LOW UP ALONG THE MISSISSIPPI RIVER. THE 17.06Z
RUN DOES APPEAR TO BE TRENDING A LITTLE TO THE EAST...BUT IS STILL
TOO FAR ON THE WEST SIDE OF THE TRACKS TO BE CONSIDERED. WITH MANY
OF THE SREF MEMBERS USING THE NAM...IT ALSO APPEARS TO BE HEAVILY
SKEWED BY IT AND IS TOO FAR WEST AS WELL WITH ITS QPF/LOW TRACK.
THE HIGHEST CONFIDENCE HAS TO BE PLACED WITH THE ECMWF WHICH HAS
BEEN NEARLY IDENTICAL FOR THE PAST 4 RUNS IN REGARD TO TIMING AND
PLACEMENT OF THE SURFACE LOW AND HEAVIEST SNOW BAND. THIS SOLUTION
TAKES THE LOW FROM ST LOUIS TOWARD NORTHERN INDIANA AND DETROIT
WITH THE HEAVIEST SNOW BAND GOING FROM EASTERN IOWA TO SOUTHEAST
WISCONSIN. THE GFS IS NOT TOO FAR OFF FROM THIS SOLUTION...BUT IS
A LITTLE FURTHER WEST OF THIS TRACK AND FASTER WITH THE LOW WHILE
THE GEM IS SOMEWHERE IN BETWEEN THE TWO.
FAVORED THE 17.00Z ECMWF WITH THIS FORECAST...SO WHILE CONFIDENCE
IS RATHER HIGH THAT THIS WINTER STORM WILL OCCUR...THE CONFIDENCE
IS NOT HIGH ENOUGH IN WHERE THE HEAVIEST SNOW BAND WILL END UP TO
ISSUE A LONG LEAD TIME WINTER STORM WATCH. PARTICULARLY SO SINCE
THE ECMWF TAKES THE HIGHER SNOW TOTALS TO THE EAST OF THE FORECAST
AREA. THE COUNTIES THAT ARE MOST LIKELY UNDER THE THREAT OF THE
HEAVIEST SNOWS ARE FROM JUNEAU/ADAMS COUNTIES IN WISCONSIN DOWN TO
CLAYTON COUNTY IN IOWA BASED ON THESE 17.00Z ECMWF/GFS/GEM
RESULTS.
.LONG TERM...THURSDAY THROUGH SUNDAY
329 AM CST MON DEC 17 2012
THE STORM WILL CONTINUE INTO THURSDAY...BUT HOW FAR WEST THE SNOW
LINGERS IS THE MAIN QUESTION. PERHAPS THE BIGGER ISSUE WILL BE
WITH THE STRONG WINDS THAT ACCOMPANY THIS STORM THAT SHOULD LEAD
TO SOME BLOWING SNOW WITH SUSTAINED WINDS REACHING 25 MPH AND
LIKELY GUSTING ABOVE 30 MPH. BY THURSDAY NIGHT...THE STORM WILL
LIKELY HAVE ENDED ACROSS WESTERN WISCONSIN WITH HIGH PRESSURE
PUSHING DOWN FROM SOUTH CENTRAL CANADA. THIS RIDGE WILL REMAIN IN
PLACE THROUGH NEXT WEEKEND AND WILL...ALONG WITH THE FRESH
SNOW PACK...PROVIDE FOR COLD AND DRY CONDITIONS WITH LOWS DROPPING
DOWN INTO THE SINGLE DIGITS.
&&
.AVIATION...THROUGH 06Z TUESDAY
1131 PM CST SUN DEC 16 2012
BIGGEST FORECAST CHALLENGE IS ON CEILINGS HEIGHTS THROUGH THE TAF
PERIOD. SURFACE HIGH OVER SOUTHEASTERN NORTH DAKOTA DRIFTS SOUTH
OVERNIGHT INTO MONDAY. 17.00Z NAM BUFKIT SOUNDING SHOWS MOISTURE
TRAPPED UNDER THE INVERSION...BUT SHALLOWING OUT WITH TIME AND EVEN
SCATTERING OUT BY AFTERNOON. HOWEVER...INFRARED SATELLITE IMAGERY
SHOWING EXTENSIVE LOW STRATUS THROUGHOUT THE
DAKOTAS/MINNESOTA/IOWA AND WISCONSIN...AND 00Z SOUNDING AT ABR
NEAR THE HIGH SHOWS SATURATED LAYER 2700 FEET DEEP. THUS RATHER
PESSIMISTIC THAT THESE LOW CLOUDS WILL SCATTER OUT ANYTIME SOON.
DID KEEP IFR CEILINGS AT KRST THROUGH 23Z THEN LIFTED INTO THE
MVFR CATEGORY. FOR KLSE...EXPECT CEILINGS IN THE UPPER IFR TO
LOWER MVFR CATEGORY THROUGH 15Z...THEN MVFR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
329 AM CST MON DEC 17 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1131 PM CST SUN DEC 16 2012
.SHORT TERM...TONIGHT THROUGH WEDNESDAY
238 PM CST SUN DEC 16 2012
MAIN FORECAST CONCERNS ARE ON PRECIPITATION CHANCES AND TYPE FOR
TUESDAY AND WEDNESDAY.
CURRENTLY AS OF 20Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED A POTENT SHORTWAVE TROUGH APPROACHING THE PACIFIC NORTHWEST
AND BROAD TROUGHING ENCOMPASSING MUCH OF THE CENTRAL U.S. INTO THE
WESTERN GREAT LAKES. WITHIN THIS BROAD TROUGHING...THERE ARE VERY
FEW SHORTWAVES THAT LOOK TO HAVE ANY IMPACT ON OUR FORECAST AREA
DURING THE NEXT FEW DAYS. THE ONLY SHORTWAVE REALLY OF NOTE WAS OVER
WESTERN PORTIONS OF MONTANA AND WYOMING. AT THE SURFACE...LOW
PRESSURE WAS OVER UPPER MICHIGAN WHILE HIGH PRESSURE COVERED THE
DAKOTAS INTO WESTERN MINNESOTA. IN-BETWEEN THE TWO...NORTHERLY WINDS
ARE DRIVING COLDER LOW LEVEL AIR INTO THE FORECAST AREA. SURFACE
TEMPERATURES HAVE FALLEN INTO THE 20S OVER PORTIONS OF SOUTHEAST
MINNESOTA WHILE THE REST OF THE AREA REMAINS MOSTLY IN THE 30S. THE
COLD AIR EXTENDS UP TO 850MB WITH 12Z SOUNDINGS FROM BIS...ABR AND
MPX SHOWING -4C TEMPERATURES. ALONG WITH THE COLDER AIR...EXTENSIVE
LOW STRATUS EXISTS FROM THE DAKOTAS INTO THE FORECAST AREA...TRAPPED
BELOW A COLD FRONTAL/SUBSIDENCE INVERSION SHOWN ON THE
AFOREMENTIONED SOUNDINGS. AS THE COLD AIR HAS BEEN FLOWING IN...SOME
FOG HAS DEVELOPED...DUE TO RECENT RAIN AND MELTING SNOW.
VISIBILITIES DROPPED EVEN DOWN TO 1/4SM MILE IN SOME PLACES IN
SOUTHEAST MINNESOTA. LAST ITEM TO NOTE IS A QUICK SNOW DEPTH
COMPARISON TO OBSERVED. THE 16.12Z NAM HAS WAY TOO MUCH SNOW ALONG
AND SOUTH OF I-90...AS ITS SNOW DEPTH INFORMATION HAS NOT UPDATED
SINCE 00Z ON THE 15TH.
TONIGHT AND MONDAY...WEAK UPPER RIDGING WITHIN THE BROAD TROUGH IS
FORECAST TO BUILD INTO THE AREA FOR TONIGHT AND MUCH OF MONDAY...
AHEAD OF THAT SHORTWAVE OVER WESTERN MONTANA AND WYOMING. GOOD MODEL
AGREEMENT EXISTS THAT THE SHORTWAVE WILL REACH WESTERN MINNESOTA BY
00Z TUESDAY. THE WEAK UPPER RIDGING BUILDING IN COMBINED WITH THE
SURFACE RIDGING COMING IN AT THE SURFACE FAVORS DRY CONDITIONS
THROUGH MONDAY. THE BIGGEST QUESTION IS IF THIS STRATUS CAN
DISSIPATE AT ALL. TOUGH TO USE THE NAM...PARTICULARLY ALONG AND
SOUTH OF I-90...SINCE IT HAS TOO MUCH SNOW AND THIS IS INFLUENCING
ITS HANDLING OF BOUNDARY LAYER. HOWEVER...BOTH GFS AND RAP SOUNDINGS
WHICH HAVE A BETTER HANDLE ON THE SNOW DEPTH SITUATION SUGGEST THE
STRATUS WILL DEFINITELY STAY IN PLACE TONIGHT. LOOKS LIKE THERE IS
ENOUGH STIRRING OF THE BOUNDARY LAYER TO PREVENT MORE THAN PATCHY
FOG. PERHAPS THERE IS A SHOT OF DIURNAL MIXING OUT THE STRATUS
TOMORROW...THOUGH MID AND HIGH CLOUDS WILL INCREASE AHEAD OF THE
APPROACHING SHORTWAVE. AS A RESULT...MAINLY CLOUDY CONDITIONS WILL
PREVAIL. THIS MEANS TEMPERATURES FOR THE MOST PART ARE GOING TO BE
INFLUENCED BY ADVECTION. A BLEND OF GUIDANCE SEEMED REASONABLE FOR
BOTH LOWS AND HIGHS.
MONDAY NIGHT AND TUESDAY...THE SHORTWAVE OVER WESTERN MINNESOTA AT
00Z TUESDAY IS SLATED TO CROSS THE AREA MONDAY NIGHT...BUT IT LOOKS
LIKE IT WILL COME THROUGH WITH LITTLE FANFARE OUTSIDE OF SOME
MID/HIGH CLOUDS. THIS IS BECAUSE OF PLENTIFUL DRY AIR IN-BETWEEN
THESE MID/HIGH CLOUDS AND A POSSIBLE HANGING AROUND VERY LOW STRATUS
DECK. OF MORE SIGNIFICANCE IS LATE IN THE NIGHT AND HEADING INTO THE
DAY TUESDAY...WHEN WARM ADVECTION IMPACTS FROM THE POTENT TROUGH
APPROACHING THE PACIFIC NORTHWEST CURRENTLY BEGIN TO MOVE IN. AT 12Z
TUESDAY...MODELS SHOW THE POTENT TROUGH...ALBEIT IN A MUCH WEAKER
STATE AFTER CROSSING THE NORTHERN ROCKIES...STRETCHED FROM THE
DAKOTAS INTO NORTHWEST IOWA. THIS TROUGH SLIDES EAST THROUGH MUCH OF
THE AREA ON TUESDAY...IN RESPONSE TO BUILDING 500MB HEIGHTS
DOWNSTREAM OF DEEP TROUGHING COMING INTO CALIFORNIA. MODELS HAVE
COME INTO GOOD AGREEMENT SHOWING A BAND OF ISENTROPIC LIFT/MID-LEVEL
FRONTOGENESIS ACCOMPANYING THIS TROUGH PASSAGE...YIELDING A BAND OF
QPF LIFTING NORTHWARD THROUGH THE FORECAST AREA DURING THE DAY
TUESDAY. PRECIPITATION COULD DEVELOP AS EARLY AS AFTER MIDNIGHT
MONDAY NIGHT AS SUGGESTED BY THE 16.12Z GFS AND SOME OF THE 16.09Z
SREF ENSEMBLES. HAVE CONFINED A 20 PERCENT CHANCE FOR MONDAY NIGHT
TO SOUTHEAST MINNESOTA. GIVEN THE GOOD AGREEMENT FOR TUESDAY...
INCREASED CHANCES UP TOWARDS 50...HIGHEST NORTH OF I-90 WHERE THE
BEST CONSENSUS EXISTS. HIGHER CHANCES MAY BE NECESSARY IN FUTURE
FORECASTS. AMOUNTS DO NOT LOOK LIKE A WHOLE LOT...BETWEEN THE BAND
LIFTING NORTH AND LIFT THAT IS QUALITATIVELY MODERATE AT BEST.
PRECIPITATION TYPE COULD BE AN ISSUE...WITH THE 16.12Z NAM SHOWING A
WARM NOSE AROUND 2C AROUND 2000 FT AGL ACCOMPANYING THE BAND. THE
GFS SUGGESTS ALL SNOW AND WILL PLAY THAT ROUTE FOR NOW AS IT SEEMS
THAT THE WARM NOSE SHOULD ACTUALLY COME IN SOUTH OF THE BAND. AFTER
THE PASSAGE OF THE BAND...THE GFS AND NAM SHOWS SKIES CLEARING OUT.
THIS MAY OCCUR AND IF IT DOES...TEMPERATURES SOUTH OF I-90 COULD POP
INTO THE 40S. FOR NOW TAKING A CONSENSUS APPROACH AS THE ECMWF
SUGGESTS A SLOWER LIFT NORTH OF THE BAND.
TUESDAY NIGHT AND WEDNESDAY...ATTENTION BEGINS TO SHIFT TO THE
TROUGHING OVER CALIFORNIA AT 00Z WEDNESDAY. GOOD MODEL AGREEMENT
EXISTS OF IT SLIDING ACROSS ARIZONA AND NEW MEXICO DURING THIS
PERIOD...RESULTING IN DEEPENING LOW PRESSURE ACROSS THE OKLAHOMA AND
TEXAS PANHANDLES. DOWNSTREAM...500MB HEIGHTS CONTINUE TO RISE...
PARTICULARLY ACROSS THE LOWER AND MID-MISSISSIPPI RIVER VALLEY. THIS
IN TURN SETS UP A STRENGTHENING MID-LEVEL FRONTOGENESIS ZONE
INITIALLY ACROSS COLORADO...THEN SPREADING UP THROUGH KANSAS...
EASTERN NEBRASKA AND EVENTUALLY IOWA BY WEDNESDAY AFTERNOON. THE
16.12Z NAM APPEARS TO BE AN OUTLIER IN EJECTING THE SURFACE SYSTEM
NORTH TO KANSAS CITY BY 00Z THURSDAY...COMPARED TO THE
GFS/ECMWF/UKMET/CANADIAN WHICH ALL HOLD IT BACK OVER OKLAHOMA. THE
FASTER EJECTING NAM WOULD ALLOW WARMER AIR TO ENTER SOUTHERN
SECTIONS OF THE FORECAST AREA ON WEDNESDAY AS WELL AS PRECIP INTO
SOUTH CENTRAL MINNESOTA. THE LATTER MORE FAVORED GROUP REQUIRES
HAVING SOME CHANCES OF PRECIPITATION...SNOW OR RAIN/SNOW MIX...TO
SOUTHERN SECTIONS OF THE FORECAST AREA WEDNESDAY AFTERNOON.
OTHERWISE...THE REST OF THE PERIOD IS DRY. WEAK PRESSURE GRADIENT
AFTER MIDNIGHT TUESDAY NIGHT PLUS POSSIBLE CLEARING WOULD
RESULT IN GOOD RADIATIONAL COOLING CONDITIONS...THOUGH THE EXTENT OF
CLEARING IS UNCERTAIN AT THIS TIME. PLUS...MID/HIGH CLOUDS MAY
ALREADY BE APPROACHING THE AREA ASSOCIATED WITH THE FRONTOGENESIS
TUESDAY NIGHT...THICKENING OVER THE AREA ON WEDNESDAY. THUS HAVE
STAYED TOWARD A GUIDANCE BLEND FOR BOTH HIGHS AND LOWS.
.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY
238 PM CST SUN DEC 16 2012
FOCUS CONTINUES TO BE ON THE DEEP TROUGHING COMING OUT OF NEW MEXICO
AND THE ASSOCIATED SURFACE SYSTEM IN OKLAHOMA.
ECMWF/CANADIAN/GFS/UKMET AND GFS ENSEMBLES ALL STILL SUGGEST PHASING
OF THIS TROUGHING AND A NORTHERN STREAM TROUGH DROPPING DOWN INTO
THE NORTHERN PLAINS. HOWEVER...TRENDS OF THE ABOVE MODELS ARE ALL
SHOWING THIS PHASING TAKING PLACE FARTHER EAST WITH THE TRACKS NOW
MAINLY GOING UP THROUGH INDIANA. THIS TREND IS GETTING CONCERNING
FOR PRECIPITATION FOR WEDNESDAY NIGHT AND THURSDAY...ESPECIALLY
OVER THE NORTHWEST 1/3 OR SO WHERE IT COULD END UP DRY. CERTAINLY
PLENTY OF TIME FOR ADJUSTMENTS FOR THE TRACK GIVEN THAT THE DEEP
TROUGH PORTION IS STILL SOUTH OF THE ALEUTIANS. ADJUSTED THE
PRECIPITATION CHANCES SLIGHTLY DOWNWARD FOR WEDNESDAY NIGHT AND
THURSDAY TO ACCOUNT FOR THE SOUTHEAST TREND...BUT AT LEAST AT THIS
TIME THE SOUTHEAST HALF OF THE FORECAST AREA STILL LOOKS GOOD TO
PICK UP SOME ACCUMULATING SNOW.
AFTER THE WEDNESDAY NIGHTTHURSDAY SYSTEM...THE PATTERN LOOKS QUIET
WITH UPPER RIDGING DOMINATING THE WESTERN HALF OF THE U.S. OR SO AND
THE FORECAST AREA IN WEST TO NORTHWEST FLOW AND HIGH PRESSURE AT THE
SURFACE. CERTAINLY SOME COLDER AIR WILL COME DOWN IN THE WAKE OF THE
SYSTEM...SENDING TEMPERATURES DOWN TO NEAR OR JUST BELOW NORMAL...
BUT IT APPEARS THIS WILL BE SHORT-LIVED AS 500MB HEIGHTS RISE.
&&
.AVIATION...THROUGH 06Z TUESDAY
1131 PM CST SUN DEC 16 2012
BIGGEST FORECAST CHALLENGE IS ON CEILINGS HEIGHTS THROUGH THE TAF
PERIOD. SURFACE HIGH OVER SOUTHEASTERN NORTH DAKOTA DRIFTS SOUTH
OVERNIGHT INTO MONDAY. 17.00Z NAM BUFKIT SOUNDING SHOWS MOISTURE
TRAPPED UNDER THE INVERSION...BUT SHALLOWING OUT WITH TIME AND EVEN
SCATTERING OUT BY AFTERNOON. HOWEVER...INFRARED SATELLITE IMAGERY
SHOWING EXTENSIVE LOW STRATUS THROUGHOUT THE
DAKOTAS/MINNESOTA/IOWA AND WISCONSIN...AND 00Z SOUNDING AT ABR
NEAR THE HIGH SHOWS SATURATED LAYER 2700 FEET DEEP. THUS RATHER
PESSIMISTIC THAT THESE LOW CLOUDS WILL SCATTER OUT ANYTIME SOON.
DID KEEP IFR CEILINGS AT KRST THROUGH 23Z THEN LIFTED INTO THE
MVFR CATEGORY. FOR KLSE...EXPECT CEILINGS IN THE UPPER IFR TO
LOWER MVFR CATEGORY THROUGH 15Z...THEN MVFR.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
238 PM CST SUN DEC 16 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...RABERDING
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
456 AM MST MON DEC 17 2012
.SHORT TERM...WE/RE SETTING UP FOR A VERY WINDY 12-18HRS IN THE
HIGH COUNTRY AND FRONT RANGE FOOTHILLS. ALREADY SEEING WLY SFC
WINDS GUSTING IN THE 50-55 MPH RANGE AT A NUMBER OF HIGH MTN
MONITORING SITE. THE CROSS MTN PRES GRADIENT CONTINUES TO
INCREASE WITH A 8MB DEN-GJT GRADIENT AT THIS HOUR...AND THE RUC
WAS ALSO INDICATING A STRENGTHENING MTN TOP STABLE LAYER WITH
SLIGHT WARMING ALOFT. IN ADDITION...BOTH THE RUC AND NAM SHOW A
LEE SIDE MTN WAVE AMPLYING THROUGH THE DAY. AS THIS IS GOING
ON...MODELS SHOW THE NOSE OF A POWERFUL PACIFIC JET REACHING
NWRN COLORADO THIS AFTERNOON...AND TRAVERSING THE NRN HALF OF
THE STATE OVERNIGHT WITH THE ARRIVAL OF EVEN STRONGER WINDS AT ITS
CORE. ITS OVERNIGHT WHEN MODELS SHOW THESE ESPLY STRONG WINDS
LOWERING IN ALTITUDE TO NEAR MTN TOP LEVEL. NOT OUT OF THE
QUESTION THAT WINDS ABOVE TIMBERLINE COULD EXCEED 70 MPH CREATING
SERIOUS WHITEOUT CONDITIONS. HOW FAR SOUTH MIGHT WE EXPECT ALL
THIS. AT THIS TIME IT WOULD APPEAR MTN AREAS ROUGHLY ALONG AND
NORTH OF INTERSTATE 70 WILL BE GROUND ZERO. MTN ZONE 31 IS
PRESENTLY UNDER A WINTER STORM WARNING..AND NRN MTN ZONE 33 A
WINTER WEATHER ADVISORY. NO CHANGES TO CURRENT HIGHLIGHTS AT THIS
TIME EVEN THOUGH FEW N-CENTRAL MTN LOCALES REPORTING ACCUMULATING
SNOWFALL ATTM...WITH ONLY LIGHT SNOWFALL UP AT EISENHOWER TUNNEL
VIA CDOT MTN CAMS. DO NOT SEE MUCH IN THE WAY OF SNOW
ACCUMULATION IN THE HIGH COUNTRY THIS MORNING AND POSSIBLY INTO
EARLY AFTERNOON WITH POOR LAPSE RATES OVER THE AREA. ITS LATE
THIS AFTERNOON AS WINDS INCREASE THAT THE INSTABILITY INCREASES
AND MOISTURE DEEPENS ACCORDING TO MODEL SOUNDINGS AND CROSS
SECTIONS. BUT ITS OVERNIGHT WHEN EVERYTHING COMES TOGETHER FOR A
NASTY SITUATION IN THE HIGH COUNTRY. THE WINTER WEATHER ADVISORY
FOR ZONE 34 MAY NEED TO BE UPGRADED TO A STORM WARNING OR POSSIBLY
A BLIZZARD WARNING SHOULD WINDS AND SNOWFALL BECOME GREATER THAN
NOW EXPECTED. MAY ALSO NEED TO ADD MTN ZONE 34 TO HIGHLIGHTS IF
THE CORE OF THE JET SAGS FARTHER SOUTH.
MEANWHILE...ON THE PLAINS WESTERLY FLOW OFF THE FRONT RANGE WILL
WARM TEMPS WELL ABOVE AVERAGE TODAY...PARTICULARLY IN THE WINDIER
AREA ALONG THE BASE OF THE FOOTHILLS. COULD SEE GUSTS IN THE 30-40
MPH IN THE CHINOOK ZONE WEST OF I-25 AND 15-30 MPH FARTHER OUT
ACROSS THE PLAINS. SFC WINDS ON THE PLAINS EXPECTED TO DECOUPLE
FROM THE 130+KT WINDS ALOFT THIS EVENING. PLAINS WILL ALSO REMAIN
DRY THROUGH ALL THIS...EXCEPT PERHAPS UP ALONG THE WYOMING BORDER
WHERE A FEW SNOW SHWRS MAY MOVE OFF THE FOOTHILLS OVERNIGHT.
.LONG TERM...MAIN CONCERN WILL BE CONTINUED WIND AND SNOW IN THE
MOUNTAINS ON TUESDAY...AND THEN DEVELOPING SNOW AND COLDER
TEMPERATURES ON THE PLAINS LATE TUESDAY NIGHT AND WEDNESDAY. AS
FORECAST CONFIDENCE INCREASES WITH CONSISTENT MODEL SOLUTIONS IT
APPEARS THIS WILL BE THE FIRST WIDESPREAD SNOW EVENT SINCE EARLIER
THIS FALL. FOR TUESDAY..MOISTURE DEPTH IS RATHER SHALLOW IN THE
MOUNTAINS SO EXPECT MAINLY LIGHT SNOWFALL DURING THE DAY. MOISTURE
DEPTH INCREASES LATE TUESDAY AND TUESDAY NIGHT AS THE MAIN UPPER
TROF APPROACHES COLORADO AND THEN MOVES ACROSS THE STATE ON
WEDNESDAY AS A STRONG OPEN WAVE. QG FIELDS SHOWING FAIRLY STRONG
UPWARD ASCENT AS THE TROF PASSES BY. SURFACE LOW PRESSURE WILL BE
DEEPENING TUESDAY NIGHT ACROSS SOUTHEAST COLORADO WHICH WILL
INCREASE WINDS FROM THE NORTH AND NORTHEAST AND AIRMASS SATURATES.
COMPILATION OF MODELS SHOWING ANYWHERE FROM 2-6 INCHES OF SNOW
OVER THE PLAINS BY LATE WEDNESDAY GIVEN A PERIOD OF 8-12 HOURS OF
SNOWFALL. GIVEN THE AMOUNT OF WINDS WOULD EXPECT WINTER WEATHER
ADVISORIES MAY BE NEEDED AT SOME POINT ON THE PLAINS BUT STILL
HAVE TO TIME TO NARROW DOWN THE DETAILS.
THE SNOW WILL DECREASE WEDNESDAY AFTERNOON WITH GRADUAL CLEARING
EXPECTED WEDNESDAY NIGHT ACROSS THE STATE. CROSS SECTIONS
INDICATING STRONGER WINDS DEVELOPING AGAIN BEHIND THE TROF OVER
THE MOUNTAINS AND EAST SLOPES. THIS MAY RESULT IN ISSUES WITH
BLOWING SNOW OVER THE FOOTHILLS AND ADJACENT PLAINS. LOOKING FOR A
DRY PERIOD WITH MODERATING TEMPERATURES FOR THURSDAY THROUGH THE
WEEKEND. AS A SIDE NOTE...LONG RANGE MODELS ARE SHOWING ANOTHER
POSSIBLE STORM DEVELOPING AROUND CHRISTMAS GIVE OR TAKE A DAY ON
EITHER SIDE. STILL A LOT OF VARYING SOLUTIONS SO WON`T GET TOO
EXCITED YET.
&&
.AVIATION...WINDS MAIN CONCERN IN THE DENVER AREA TODAY. BJC NEAR
THE FOOTHILLS ALREADY SEEING PERIODIC WEST WINDS OF 20-25KTS.
WINDS EVEN STRONGER THAN THIS LIKELY TO BECOME MORE PERSIST AT
BJC AS THE MORNING PROGRESSES WITH WLY GUSTS APCHG 45KTS BY
AFTERNOON. SLY WINDS AT DIA AND APA ALSO EXPECTED TO PICK UP IN
THE NEXT FEW HRS AS THEY SHIFT TO A WESTERLY COMPONENT. COULD SEE
GUSTS IN THE 20-35KTS AT BOTH AIRPORTS BY MID TO LATE
AFTERNOON...AND THROUGHOUT THE AFTERNOON. NO PRECIP AT THIS
TIME...SO VFR CIGS AND VSBYS. BY NIGHTFALL SHOULD SEE A STEADY
DROP OF IN WINDS AT DIA AND APA...BUT GUSTY WLY WINDS LIKELY TO
CONTINUE AT BJC FOR MUCH OF THE EVENING.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 5 AM MST TUESDAY FOR COZ031.
WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY FOR COZ033.
&&
$$
SHORT TERM...BAKER
LONG TERM....ENTREKIN
AVIATION...BAKER
AREA FORECAST DISCUSSION
NWS TAUNTON MA
952 AM EST MON DEC 17 2012
.SYNOPSIS...
A WINTRY MIX OF PRECIPITATION WILL CONTINUE TODAY TO THE NORTH OF MA
TURNPIKE AND AWAY FROM THE IMMEDIATE COAST...RESULTING IN HAZARDOUS
TRAVEL. THE PRECIPITATION SHOULD FINALLY CHANGE TO ALL RAIN TONIGHT
AND TUESDAY...WITH THE NEXT WAVE OF LOW PRESSURE. ANOTHER
POTENTIALLY STRONG LOW PRESSURE SYSTEM SHOULD BRING ANOTHER ROUND OF
MAINLY RAIN AND GUSTY WINDS LATE THU INTO FRI.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
10 AM UPDATE...
ALLOWED FREEZING RAIN TO EXPIRE FOR N CT AND ADJACENT W MA AS
TEMPERATURES HAVE CLIMBED TO ABOVE FREEZING. WINTER WEATHER
ADVISORY REMAINS IN EFFECT FOR MUCH OF INTERIOR MA AND SW NH WHERE
READINGS WILL BE SLOW TO RISE THROUGH AFTERNOON. 12Z HRRR HAS A
GOOD HANDLE ON SURFACE TEMPERATURES AND BRINGS MUCH OF NE MA ABOVE
32F BY NOON...WHILE COLD AIR REMAINS LOCKED FARTHER INLAND DUE TO
WEAK FLOW.
OTHERWISE EXPECT LITTLE CHANGE THROUGH AFTERNOON WITH PERIODS OF
RAIN/DRIZZLE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
***A ROUND OF HEAVY RAIN EXPECTED LATE TONIGHT INTO TUESDAY***
TONIGHT AND TUESDAY...
WE STILL MAY BE DEALING WITH ISOLATED POCKETS OF LIGHT FREEZING RAIN
DURING THE EARLY EVENING ACROSS THE HIGHER TERRAIN OF THE MONADNOCKS
IN SOUTHERN NH. THIS IS BASED ON THE SHALLOW COLD AIR WHICH IS
BEING DEPICTED MUCH BETTER BY SOME OF OUR HIGH RESOLUTION MODELS
HOWEVER...THE NEXT LOW PRESSURE SYSTEM APPROACHING FROM THE WEST
SHOULD ALLOW THESE TEMPS TO RISE OVERNIGHT BRINGING AN END TO ANY
ICING THREATS.
THIS NEXT WAVE OF LOW PRESSURE APPROACHES LATE TONIGHT AND INTO
TUESDAY. THIS SHOULD BRING A PERIOD OF HEAVY RAIN...THAT MAY RESULT
IN TYPICAL NUISANCE URBAN AND POOR DRAINAGE STREET FLOODING. THERE
ALSO IS SOME ELEVATED INSTABILITY...SO DID INCLUDED A SLIGHT CHANCE
OF THUNDER IN THE FORECAST.
THE HEAVIEST/STEADIEST OF THE RAIN SHOULD COME TO AN END BY MID TO
LATE AFTERNOON ON TUE...BUT SOME SCATTERED SHOWERS WILL PERSIST. IN
ADDITION...AREAS OF FOG WILL BE AN ISSUE TONIGHT/TUE AND SOME OF IT
MAY BE LOCALLY DENSE AT TIMES. HIGH TEMPS SHOULD RECOVER WELL INTO
THE 50S ACROSS SOUTHEAST NEW ENGLAND BY TUESDAY AFTERNOON...AS THIS
AREA LOOKS TO WARM SECTOR.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
HIGHLIGHTS...
* A FEW LEFT OVER RAIN/SNOW SHOWERS POSSIBLE TUE NIGHT/WED
* MAINLY RAIN EXPECTED LATE THU/FRI BUT POSSIBLY BEGINS AS SOME
ICE/SNOW ACROSS THE INTERIOR
* A PERIOD OF STRONG WINDS POSSIBLE ON FRIDAY
* COLDER WEATHER LIKELY BY NEXT WEEKEND
DETAILS...
TUESDAY NIGHT AND WEDNESDAY...
VERTICALLY STACKED LOW PRESSURE WILL SLOWLY MOVE AWAY FROM THE
REGION. WHILE MUCH OF TUE NIGHT/WED SHOULD END UP DRY...A FEW LEFT
OVER RAIN AND PERHAPS EVEN A FEW SNOW SHOWERS WILL BE POSSIBLE
ACROSS THE INTERIOR. HOWEVER...PRECIPITATION AMOUNTS SHOULD BE
RATHER LIGHT.
LATE THURSDAY AND FRIDAY...
A POTENTIALLY STRONG LOW PRESSURE SYSTEM WILL BRING MAINLY RAIN TO
THE REGION LATE THU/FRI AS ONE MAIN LOW HEADS UP TOWARDS THE GREAT
LAKES...FLOODING OUR REGION WITH MILD AIR. HOWEVER...IT MAY BE COLD
ENOUGH AT THE ONSET FOR A PERIOD OF ICE/SNOW ACROSS PORTIONS OF
THE INTERIOR. A SECONDARY LOW MAY TRY TO DEVELOP SOMEWHERE NEAR
THE MID ATLANTIC/NORTHEAST COAST. IF THAT ENDS UP TRACKING TO OUR
WEST AS WELL...A STRONG SOUTHERLY LOW LEVEL JET MAY RESULT IN A
PERIOD OF STRONG WINDS MIXING DOWN TO THE SURFACE. ALWAYS A
CHALLENGE TO SEE HOW MUCH OF THESE WINDS WOULD BE ABLE TO MIX DOWN
IN THE INVERSION...BUT SOMETHING TO CERTAINLY WATCH.
SATURDAY AND SUNDAY...
MODELS IN GENERALLY AGREEMENT IN AN UPPER LEVEL TROUGH SETTING UP
ACROSS NEW ENGLAND. THIS SHOULD BRING COLDER WEATHER TO THE REGION.
FOR NOW WE JUST WENT WITH SLIGHT CHANCE POPS...AS UPPER TROUGH
OVERHEAD MAY RESULT IN A FEW FLURRIES/SNOW SHOWERS AT TIMES. THE
ONE THING WILL HAVE TO WATCH IS THE POTENTIAL FOR AN INVERTED TROUGH
TO SETUP. THE 00Z ECMWF HINTS AT THAT FEATURE...WHICH IF HAPPENED
COULD RESULT IN MORE IN THE WAY OF PRECIPITATION. THOSE FEATURES
ARE ALWAYS TRICKY TO FORECAST EVEN IN THE VERY NEAR TERM...SO NO
POINT TALKING MORE ABOUT IT AT THIS POINT BUT ITS SOMETHING TO KEEP
AN EYE ON.
&&
.AVIATION /15Z MONDAY THROUGH FRIDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
15Z UPDATE...
MODERATE CONFIDENCE. LITTLE CHANGE IN CONDITIONS THROUGH EARLY
AFTERNOON WITH IFR/MVFR. LIGHT ICING REMAINS A CONCERN ACROSS
INTERIOR MA THROUGH MID AFTERNOON AND ACROSS SW NH INTO THIS
EVENING...GENERALLY 1/10 INCH. PERIODS OF RAIN/DRIZZLE
ELSEWHERE THROUGH TONIGHT.
KBOS TAF...MODERATE CONFIDENCE IN TAF. CIGS MAY BRIEFLY IMPROVE TO
MVFR /OVC012/ FOR A TIME THIS AFTERNOON.
KBDL TAF...MODERATE CONFIDENCE IN TAF. CIGS WILL VARY BETWEEN IFR
/OVC008/ AND MVFR /OVC015/ THROUGH AFTERNOON.
OUTLOOK...TONIGHT THROUGH FRIDAY...
TONIGHT NIGHT AND TUESDAY...MODERATE TO HIGH CONFIDENCE. IFR TO
LIFR CONDITIONS EXPECTED IN RAIN AND AREAS OF FOG. LOW RISK OF AN
ISOLATED THUNDERSTORM OR TWO LATE
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...MODERATE CONFIDENCE. SHOULD
SEE GRADUAL IMPROVEMENT TO VFR CONDITIONS BUT UNCERTAIN ON THE EXACT
TIMING. GUSTY NORTHWEST WINDS EXPECTED ON WED.
THURSDAY AND FRIDAY...MODERATE CONFIDENCE. MVFR TO IFR CONDITIONS
POSSIBLE LATE THU INTO FRIDAY AS THE NEXT SYSTEM MOVES INTO THE
REGION.
&&
.MARINE...
HIGH CONFIDENCE FOR SMALL CRAFT ADVISORY CONDITIONS OUTSIDE BOSTON
HARBOR AND NARRAGANSETT BAY. HAVE EXTEND SCA FOR THE BAYS AS 5FT
WAVES WILL BE SLOW TO REDUCE AS STRONG WIND SPEEDS WILL PREVAIL.
VSBYS WILL REMAIN LOW THROUGH MOST OF THE PERIOD ESP IN HEAVIER
RAIN SHOWERS.
OUTLOOK...TONIGHT THROUGH FRIDAY...
TONIGHT AND TUESDAY...MODERATE TO HIGH CONFIDENCE. SEAS WILL REMAIN
ABOVE SCA THRESHOLDS ACROSS THE OUTER-WATERS...BUT WINDS SHOULD
TEMPORARILY DIMINISH.
TUESDAY NIGHT AND WEDNESDAY...MODERATE TO HIGH CONFIDENCE. IN THE
WAKE OF LOW PRESSURE EXPECT WINDS TO INCREASE OUT OF THE NORTHWEST.
WILL PROBABLY NEED A GALE WATCH VERY LATE TUE NIGHT INTO WED...AS
THERE IS THE POTENTIAL FOR 35 TO 40 KNOT WIND GUSTS OVER THE OPEN
WATERS. ITS CLOSE TO A 5TH PERIOD EVENT SO DECIDED TO LET THE NEXT
SHIFT DECIDE ON THESE POSSIBLE HEADLINES.
THURSDAY AND FRIDAY...MODERATE CONFIDENCE. WINDS/SEAS WILL DIMINISH
TEMPORARILY. HOWEVER...THE NEXT LOW PRESSURE SYSTEM WILL BRING THE
POTENTIAL FOR A PERIOD OF GALE FORCE WIND GUSTS AND HIGH SEAS.
&&
.TIDES/COASTAL FLOODING...
EASTERLY WINDS ALONG WITH THE POTENTIAL FOR A 1 FOOT STORM SURGE MAY
RESULT IN SOME SPLASH OVER DURING TODAY/S MID DAY HIGH TIDE ALONG
THE EASTERN MA COAST. THEREFORE...WE WILL GO AHEAD AND ISSUE A
COASTAL FLOOD STATEMENT FOR THIS REGION.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...WINTER WEATHER ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR
MAZ002>010-012-026.
NH...WINTER WEATHER ADVISORY UNTIL 8 PM EST THIS EVENING FOR NHZ011-
012-015.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
ANZ231>234.
SMALL CRAFT ADVISORY UNTIL 5 PM EST TUESDAY FOR ANZ235-237-250-
251-254>256.
&&
$$
SYNOPSIS...FRANK/DUNTEN
NEAR TERM...JWD
SHORT TERM...FRANK
LONG TERM...FRANK
AVIATION...JWD
MARINE...BELK/FRANK/DUNTEN
TIDES/COASTAL FLOODING...DUNTEN
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
654 AM EST MON DEC 17 2012
.PREV DISCUSSION... /ISSUED 411 AM EST MON DEC 17 2012/
SHORT TERM /TODAY THROUGH TUESDAY/...
MAIN FCST CONCERN REMAINS CHC FOR SVR CONVECTION TODAY. 00Z MODEL
RUNS NOT SHOWING MUCH CHANGE FROM PREVIOUS RUNS...BEST TIMING FOR
VERTICAL WIND SHEAR AND INSTABILITY WILL BE 15Z-21Z. PROBLEM IS
THAT WE SAW NORTH WINDS MUCH OF THE DAY AND EVENING SUNDAY...IN
RESPONSE TO LOW FROM LARGE PERSISTENT PRECIP AREA...WHICH MINIMIZED
NORTHWARD MOISTURE TRANSPORT. LATEST RAP ANALYSIS ALSO SHOWING THAT
MUCAPE REMAINS NEAR ZERO IN THE REGION EXCEPT ALONG THE GULF COAST.
USUALLY SEE ELEVATED INSTABILITY SURGING NORTHEAST AT THIS TIME OF
NIGHT PRECEDING FRONT AND STORMS. 06Z NAM STARTING TO AGREE WITH
LATEST ANALYSIS IN THE NEAR TERM BUT STILL APPEARS A LITTLE TOO
QUICK BRINGING HIGHER THETA-E AIR AND HIGHER CAPE NORTH BY 15Z.
ASSUMING MODELS ON TRACK WITH INSTABILITY...SHOULD SEE SVR THREAT
DEVELOP AFTER 15Z. DO NOT SEE ANY THREAT OF HAIL GREATER THAN ONE
INCH. DAMAGING WINDS AND AN ISOLATED TORNADO THREAT REMAIN POSSIBLE
BUT CONTINGENT ON MOISTURE TRANSPORT AND INSTABILITY DEVELOPING AS
FCST. WILL HAVE TO WATCH REAL TIME ANALYSIS CLOSELY THIS MORNING.
PRECIP WILL MOVE OUT QUICKLY TONIGHT. NO ISSUES WITH FCST BEYOND
THIS. DRY AIR SHOULD FILTER IN SLOWLY BUT ENOUGH TO PRECLUDE
DEVELOPMENT OF FOG. USED MAV/MET/ECMWF MOS BLEND FOR TEMPS.
SNELSON
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
MAIN FORECAST CONCERN IN THE EXTENDED PERIODS IS THE FAIRLY STRONG
COLD FRONT EXPECTED ON THURSDAY. WEAK RIDGING OVER THE SOUTHEAST
AT THE BEGINNING OF THE EXTENDED PERIODS...WITH NEARLY NEARLY
ZONAL UPPER LEVEL FLOW...SFC HIGH AND DRY CONDITIONS ON WEDNESDAY.
ALTHOUGH THERE ARE SOME DISCREPANCIES EXTENDED MODELS ARE IN GOOD
AGREEMENT WITH GENERAL PATTERN MIDWEEK. AN UPPER LEVEL SHORT WAVE
CROSSES THE ROCKIES ON WEDNESDAY LIFTING INTO THE OHIO VALLEY BY
THURSDAY AFTERNOON. GFS IS DEEPER AND CUTS OFF THE LOW BY THURSDAY
AFTERNOON...ECMWF IS SLOWER TO CUT OFF LOW BUT BY THURSDAY NIGHT
BOTH MODELS ARE SIMILAR IN LOCATION AND STRENGTH OF LOW. WITH WEAK
RIDGING AND SURFACE HIGH SHIFTING EAST ON WEDNESDAY MODELS ARE IN
AGREEMENT THAT BEST MOISTURE RETURNS THURSDAY MORNING AHEAD OF THE
COLD FRONT WHICH MOVES ACROSS THE FORECAST AREA RATHER QUICKLY BY
THURSDAY EVENING. INSTABILITY IS LIMITED HOWEVER BOTH GFS AND
ECMWF AREA SHOWING GOOD SHEAR...AND GIVEN THE STRENGTH OF THE FRONT
WILL CONTINUE ISOLATED THUNDERSTORMS DURING THE DAY. RAINFALL
RATES WILL BE HALF INCH OR LESS BASED UPON THE SPEED OF THE STORM.
ZONAL FLOW ALOFT AND SURFACE HIGH PRESSURE BUILD BACK IN FOR THE
WEEKEND. GFS SHOWING SOME MOISTURE RETURN SATURDAY BUT MAINLY
EXPECT AN INCREASE IN CLOUDS ACROSS THE FORECAST AREA SATURDAY AND
SUNDAY. GUIDANCE TEMPERATURES ARE PRETTY CLOSE AND WILL TAKE A
BLEND OF MAV/ECMWF MOS THROUGH THE EXTENDED PERIODS.
ATWELL
&&
.AVIATION...
12Z UPDATE...
LIFR CIGS WERE SLOW TO DEVELOP BUT FINALLY DEVELOPED IN NORTH GA
AIRPORTS INCLUDING ATL. PRECIP MOVING IN THIS MORNING AS WELL BUT
CIGS/VSBYS SLOW TO FALL TO THE WEST WHERE RAIN HAS BEEN FALLING.
WILL CONTINUE TO MONITOR TRENDS BUT EXPECT CIGS TO FALL TO NEAR
IFR ONCE RAIN COOLS AND FURTHER SATURATES LOW LEVELS. INSTABILITY
HAS BEEN SLOW TO DEVELOP OVERNIGHT...NOW EXPECT MOST INSTABILITY
THIS AFTERNOON TO BE OVER MIDDLE GA SO HAVE REMOVED TSRA FROM FCST
FOR ATL METRO TAFS AND AHN. WINDS HAVE ALREADY BECOME SSW AND
SHOULD SWITCH TO WEST AROUND 21Z WHEN PRECIP TAPERS OFF AND FRONT
MOVES IN.
//ATL CONFIDENCE...12Z UPDATE...
MEDIUM CONFIDENCE ON IFR CIGS THIS MORNING.
HIGH ON ALL OTHER ELEMENTS.
SNELSON
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 62 47 62 36 / 90 20 5 5
ATLANTA 64 47 61 41 / 90 10 5 5
BLAIRSVILLE 57 41 56 29 / 90 20 5 5
CARTERSVILLE 63 42 59 32 / 100 10 5 5
COLUMBUS 69 50 65 40 / 90 10 5 5
GAINESVILLE 60 45 60 39 / 90 20 5 5
MACON 70 49 66 35 / 90 20 5 5
ROME 64 41 60 33 / 90 10 5 5
PEACHTREE CITY 66 42 62 32 / 90 10 5 5
VIDALIA 74 56 69 42 / 80 50 0 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...SNELSON
LONG TERM....ATWELL
AVIATION...SNELSON
AREA FORECAST DISCUSSION
NWS LINCOLN IL
528 AM CST MON DEC 17 2012
.DISCUSSION...
ISSUED 230 AM CST MON DEC 17 2012
PRIMARY FOCUS FOR THIS FORECAST INVOLVES THE MAJOR STORM SYSTEM
THAT WILL BE CROSSING THE MIDWEST WEDNESDAY NIGHT AND THURSDAY...
INCLUDING PRECIPITATION TYPES AND STRONG WINDS. RAIN POTENTIAL
LATER TODAY IS A SECONDARY CONCERN.
SHORT TERM...TODAY THROUGH TUESDAY...
MAIN FOCUS FOR ANY RAIN TODAY IS WITH A SURFACE LOW CURRENTLY OVER
SOUTH CENTRAL MISSOURI...WITH A FRONTAL BOUNDARY ARCING NORTHEAST
ALONG THE OHIO RIVER. BEST PRECIPITATION CHANCES WILL BE NEAR THE
OHIO VALLEY AS THE LOW RIDES UP THE BOUNDARY...BUT SOME OF THE
RAIN FROM THIS SYSTEM MAY REACH INTO SOUTHEAST ILLINOIS. IN
ADDITION...A SHORTWAVE CURRENTLY OVER KANSAS/OKLAHOMA WILL SWING
ACROSS ILLINOIS THIS AFTERNOON. GFS AND CANADIAN MODELS DEVELOP
SOME LIGHT QPF FROM MISSOURI NORTHEAST INTO CENTRAL ILLINOIS
PRIMARILY THIS AFTERNOON...ALTHOUGH SOUNDINGS OFF THE RAP MODEL
SHOW QUITE A BIT OF DRY AIR ABOVE THE PERSISTENT INVERSION AROUND
900 MB. HIGHEST POPS TODAY WILL MAINLY BE SOUTH OF I-72...BUT WILL
CARRY SOME SLIGHTS NORTHWEST OF THE ILLINOIS RIVER. ANOTHER
SHORTWAVE WILL TRACK INTO THE WESTERN GREAT LAKES ON TUESDAY...BUT
IT STILL APPEARS ANY ASSOCIATED PRECIP WITH THIS FEATURE WILL
REMAIN TO OUR NORTH.
LONG TERM...WEDNESDAY THROUGH SUNDAY...
A STRONG UPPER WAVE COMING ONTO THE PACIFIC COAST ON TUESDAY IS
STILL ON TRACK TO HELP DEVELOP A MAJOR STORM SYSTEM ACROSS THE
CENTRAL PLAINS ON WEDNESDAY. STILL A FAIR AMOUNT OF SPREAD AMONG
THE EVENING MODELS ON TIMING AND PLACEMENT OF THE CENTRAL
LOW. EACH MODEL SHOWING SOME CONSISTENCY WITH ITS PREVIOUS
RUN...BUT NOT AMONGST EACH OTHER...WITH THE NAM THE FURTHEST
NORTHWEST AND THE ECMWF THE FURTHEST SOUTH. THIS IS GOING TO BE
CRITICAL IN DETERMINING THE EXACT PLACEMENT OF HEAVY SNOW ACROSS
PORTIONS OF THE MIDWEST. GIVEN THAT THE PARENT WAVE HAS NOT BEEN
ADEQUATELY SAMPLED BY THE UPPER AIR NETWORK YET...THESE
INCONSISTENCIES ARE NOT UNUSUAL.
THIS FORECAST PACKAGE WILL GO WITH A GFS/ECMWF BLEND...WITH THE
LOW ROUGHLY PARALLELING THE ILLINOIS RIVER LATE WEDNESDAY NIGHT
AND EARLY THURSDAY. RAIN IS EXPECTED TO OVERSPREAD THE AREA
WEDNESDAY EVENING...WITH SOME POTENTIAL FOR THUNDER IN THE
SOUTHEAST CWA LATE WEDNESDAY NIGHT IN THE WARM SECTOR. THE COLD
AIR WILL RAPIDLY POUR IN BEHIND THE LOW ON THURSDAY MORNING...WITH
FORECAST SOUNDINGS SHOWING A FAIRLY CLEAN AND RAPID TRANSITION
FROM RAIN TO SNOW GOING FROM WEST TO EAST ACROSS THE CWA. HEAVIEST
SNOWFALL IN THE DEFORMATION ZONE WOULD BE MORE ACROSS EASTERN IOWA
INTO SOUTHERN WISCONSIN...BUT AN INCH OR TWO OF SNOW IS POSSIBLE
NORTH OF A BLOOMINGTON TO CANTON LINE. ACCUMULATIONS MAY BE
HAMPERED BY THE UNSEASONABLY WARM GROUND...BUT A HEAVY FALLING
SNOW MAY BE ENOUGH TO OVERCOME THAT. WHAT SNOW DOES FALL WILL BLOW
AROUND QUITE A BIT...AS ALL MODELS SHOW VERY WINDY CONDITIONS
DEVELOPING THURSDAY AS THE LOW PULLS AWAY. BUFKIT SOUNDINGS OFF
THE GFS SHOW SURFACE GUSTS AROUND 45 MPH THURSDAY AFTERNOON AND
EARLY EVENING. ANY LINGERING SNOW SHOULD TAPER OFF THURSDAY
EVENING.
THE REMAINDER OF THE FORECAST PERIOD IS EXPECTED TO BE QUIET...
WITH TEMPERATURES RUNNING BELOW NORMAL.
GEELHART
&&
.AVIATION...
ISSUED 520 AM CST MON DEC 17 2012
MVFR CONDTIONS...WITH LOCAL IFR CIGS...ARE EXPECTED TO CONTINUE
THIS FORECAST PERIOD. WEAK WEATHER SYSTEM WILL MOVE ACROSS THE
AREA TODAY WHICH MAY BRING SOME LIGHT RAIN TO PARTS OF THE
FORECAST AREA BUT COVERAGE STILL APPEARS TO BE TOO LIMITED TO
INCLUDE IN TAFS OTHER THAN VCSH. FORECAST SOUNDINGS AND TIME
HEIGHT CROSS SECTIONS CONTINUE TO SHOW THE MOISTURE TRAPPED
BELOW A RATHER STRONG LOW LEVEL INVERSION WHICH WILL BE VERY
SLOW TO BREAK OVER THE NEXT 12 TO 18 HOURS. MODELS CONTINUE TO
SUGGEST IN THE WAKE OF THE WEATHER SYSTEM THAT MOVES THRU THE
AREA TODAY...SOME BREAK UP OF THE MOISTURE MAY OCCUR IN THE LOW
LEVELS BUT WILL BE A BIT MORE CONSERVATIVE THAN WHAT MODELS WERE
INDICATING FOR THIS AFTN. WILL BRING CIGS UP TO VFR IN MOST
LOCATIONS...EXCEPT CMI...AFTER 00Z. SURFACE WINDS WILL REMAIN
LIGHT TODAY...MOSTLY OUT OF A NORTHERLY DIRECTION.
SMITH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1012 AM EST MON DEC 17 2012
.SYNOPSIS...
ISSUED AT 315 AM EST MON DEC 17 2012
LOW PRESSURE OVER EASTERN LAKE SUPERIOR WILL WEAKEN AND MOVE TOWARD
JAMES BAY TODAY. CHANCES FOR RAIN AND SNOW WILL CONTINUE TO DECREASE
THROUGH TONIGHT AS THIS OCCURS. A WEAK LOW PRESSURE SYSTEM PASSING
TO OUR SOUTH MAY BRING LIGHT RAIN AND SNOW TUESDAY AFTERNOON INTO
TUESDAY NIGHT. A MUCH STRONGER SYSTEM WILL MOVE INTO THE REGION
THURSDAY...WITH WINTER STORM CONDITIONS EXPECTED IN AT LEAST SOME
PARTS OF THE GREAT LAKES REGION.
&&
.UPDATE...
ISSUED AT 1009 AM EST MON DEC 17 2012
BROAD TROUGHINESS REMAINS OVER THE GREAT LAKES...WITH ONE RATHER
COMPACT EMBEDDED VORT LOBE EXITING EASTERN UPPER MICHIGAN. LOW LEVEL
MOISTURE REMAINS ABUNDANT...AS EVIDENT BY WIDESPREAD STRATUS AND 12Z
LOCAL SOUNDING WHICH HAD A MOISTURE-RICH PROFILE UP THROUGH H80.
TOP-DOWN DRYING ALREADY EVIDENT JUST UPSTREAM...WITH KGRB SOUNDING
SHOWING RAPID DEPLETION OF MOISTURE ABOVE H85 CENTERED INVERSION.
THIS DRYING WILL CONTINUE TO SPREAD EAST...WITH A RAPID FALL-OFF OF
MID LEVEL MOISTURE INTO THIS AFTERNOON...ESPECIALLY ACROSS NORTHERN
LOWER MICHIGAN. COMBINE THIS WITH JUST MARGINALLY UNSTABLE LOW LEVEL
PROFILES OVER LAKE MICHIGAN (HIGH RES RAP ANALYSIS SHOWED -6C H85
AIR OVER THE BIG POND)...AND ONGOING LIGHT LAKE EFFECT SNOW/RAIN
SHOWERS SHOULD TAPER OFF THROUGH EARLY AFTERNOON. MOISTURE REMAINS
SOMEWHAT DEEPER OVER LAKE SUPERIOR...SUGGESTING LIGHT RAIN/SNOW
SHOWERS CONTINUING THROUGH MUCH OF THIS AFTERNOON...PERHAPS BRINGING
SOME VERY MINOR SNOW ACCUMULATIONS (SUB ONE INCH) OVER THE FAVORED
SNOWBELTS. TEMPERATURES LOOK TO REMAIN PRETTY STEADY-STATE IN THE
MID AND UPPER 30S AS DIURNAL INFLUENCES ARE COUNTERED BY WEAKISH LOW
LEVEL CAA. ABOVE WELL HANDLED BY INHERITED FORECAST WITH ONLY
COSMETIC CHANGES NEEDED TO ACCOUNT FOR REAL-TIME RADAR TRENDS.
UPDATE ISSUED AT 700 AM EST MON DEC 17 2012
SOME FINE-TUNING...PUSHING MORNING POPS A LITTLE FURTHER SOUTH
INTO THE HTL/CAD AREAS...AND KEEPING PRECIP MIXED A FEW MORE HOURS
IN EASTERN UPPER BEFORE GOING ALL SNOW. NEWLY ARRIVING STAFF
MEMBERS REPORT SEEING A FEW WET FLAKES MIXING IN ON THE
COMMUTE...SO HAVE ADDED IN A MIX A BIT SOONER OVER THE HIGH
TERRAIN IN THE GLR AREA.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 315 AM EST MON DEC 17 2012
RATHER NEBULOUS FORECAST AS WE WELCOME THE NEW WORK WEEK...WITH MAIN
ISSUES BEING CLOUD COVER/TEMPS AND SMALL CHANCES FOR MAINLY NUISANCE
LAKE SNOW SHOWERS/FLURRIES. EARLY MORNING ANALYSIS PLACES WEAK
SURFACE LOW OVER THE EASTERN TIP OF LAKE SUPERIOR...WITH ITS
ASSOCIATED WEAK OCCLUDED FRONTAL BOUNDARY SLOWLY WORKING THROUGH
NORTHERN LOWER. JUST A SUBTLE WIND SHIFT WITH THIS FEATURE...BUT
WITH A SLIGHTLY COOLER AIR MASS GRADUALLY FILTERING INTO THE CWA
(STILL NOT VERY COLD FOR MID DECEMBER). REGIONAL RADAR MOSAIC SHOWS
EARLIER LAST BATCH OF SHOWERS EXITING THE AREA...AS WEAK SECONDARY
UPPER VORT IS TRACKING OVERHEAD...WHILE SATELLITE PICS/OBS SHOW
QUITE THE EXPANSIVE LOW STRATUS CLOUD DECK WELL ENTRENCHED ALL
THROUGHOUT THE GREAT LAKES/UPPER MIDWEST.
FOR TODAY...BROAD UPPER TROUGHING WILL CONTINUE TO DOMINATE THE
GREAT LAKES REGION...AS STRONGER SOUTHERN STREAM ENERGY LIFTS
THROUGH THE TENNESSEE VALLEY. AIRMASS THROUGH THE DAY WILL BECOME
INCREASINGLY COOL ALOFT (H8 TEMPS AROUND -6C BY MIDDAY) WHILE ALSO
DRYING OUT ACROSS NORTHERN LOWER. EASTERN UPPER WILL BE A DIFFERENT
STORY AS APPROACH OF YET ANOTHER WEAK SHORTWAVE BRINGS A BRIEF ROUND
OF DEEPER MOISTURE ACROSS EASTERN LAKE SUPERIOR. THAT SETUP IN
COMBINATION WITH MARGINAL LAKE INSTABILITY SHOULD GIVEN AT LEAST
DECENT COVERAGE OF MAINLY LIGHT LAKE SNOW SHOWERS THROUGH THE DAY
ACROSS NORTHERN CHIPPEWA COUNTY IN A MEAN WEST/NORTHWEST FLOW
REGIME. ACCUMULATIONS SHOULD BE HINDERED BY SURFACE TEMPS AT OR
SLIGHTLY ABOVE FREEZING...BUT PERHAPS UP TO AN INCH COULD FALL.
NORTHERN LOWER LOOKS MUCH MORE PALTRY AS MOISTURE IS VERY THIN AND
OVERLAKE INSTABILITY IS EVEN WORSE (DELTA T VALUES UP AROUND 12C).
THAT SETUP SHOULD GIVE US PLENTY OF LAKE STRATUS...AND MAYBE A FEW
LIGHT SNOW SHOWERS...BUT PROBABLY MORE LIKE JUST SOME FLURRIES...
WITH THOSE LIKELY TO END THROUGH THE AFTERNOON AS MOISTURE FURTHER
THINS TO BELOW 900MB. HIGHS DEFINITELY A BIT CLOSER TO NORMAL BUT
STILL ABOVE...WITH READINGS MAINLY IN THE 32-38F RANGE.
TONIGHT LOOKS EVEN MORE QUIET AS THE WEAK SURFACE LOW PROGRESSES
TOWARD JAMES BAY...WHILE STRONGER LOW PRESSURE SLIDES THROUGH THE
OHIO VALLEY. THIS WILL ALLOW LOW LEVEL RIDGING TO BUILD INTO
NORTHERN MICHIGAN THROUGH THE NIGHT. WEAKENING GRADIENT SHOULD ALLOW
FOR SOME LAND BREEZE DEVELOPMENT...THEORETICALLY HELPING PUSH SOME
OF THE LAKE STRATUS CLOSER TO THE COASTS. HOWEVER...DEGREE OF
CLEARING REMAINS TO BE SEEN...AND NOT OVERLY ENTHUSIASTIC GIVEN SUCH
WIDESPREAD STRATUS SPREAD WELL UPSTREAM THROUGH THE NORTHERN
PLAINS/UPPER MIDWEST. DON`T FORESEE MUCH IN THE WAY OF ANY LINGERING
LAKE SNOW SHOWERS AS MOISTURE IS EVEN MORE THIN...BUT SUPPOSE A
ROGUE FLURRY IS POSSIBLE. OVERNIGHT LOWS WILL BE TIED TO DEGREE OF
CLEARING...BUT GIVEN OUR RECENT HISTORY AND STRONGER LIKELIHOOD FOR
CLOUDS TO PREVAIL...FEEL WARMER IS PROBABLY BETTER...AND WILL SIDE
WITH READINGS MAINLY IN THE UPPER HALF OF THE 20S TO LOWER 30S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 315 AM EST MON DEC 17 2012
MILD AND RELATIVELY UNEVENTFUL WX WILL HOLD INTO WEDNESDAY. A
VARIETY OF OPTIONS ARE POSSIBLE AFTER THAT...THOUGH /UNEVENTFUL/
DOES NOT APPEAR TO BE ONE OF THEM. A WEAK N-S ORIENTED RIDGE AXIS
WILL BE OVER LOWER MI EARLY TUESDAY...TEMPORARILY DISLODGED BY A
VERY WEAK SURFACE WAVE TRANSITING FAR SOUTHERN LOWER MI IN THE
EVENING. SMALL PRECIP CHANCES MAY BE IN THE OFFING TUE-WED...BUT THE
MAIN SHOW WILL CLEARLY OCCUR AFTER THAT.
TUESDAY...850MB THERMAL TROF WILL BE DISPLACED EAST ACROSS LAKE
HURON DURING THE DAY...ALLOWING FOR A 2-3C RECOVERY TO -4 TO -7C.
THE STRONGEST WARM ADVECTION/ISENTROPIC ASCENT WILL FOCUS JUST TO
OUR SW...MOVING TOWARD SOUTHERN LAKE MI IN THE AFTERNOON. THIS IS IN
ADVANCE OF A 1004MB LOW MOVING EAST FROM CENTRAL IOWA TO NORTHERN
IL. FGEN FORCING WILL CONTRIBUTE TO A BAND OF MOISTENING ALOFT THAT
EVENTUALLY REACHES NE WI...CENTRAL AND SOUTHERN LOWER MI LATE. DRIER
AIR BELOW 800MB WILL BE MORE STUBBORN TO DISLODGE...BUT MODEL
SOUNDINGS ARE MORE OPTIMISTIC IN PROGGING PRECIP DOWN TO THE SURFACE
BY LATE AFTERNOON/EARLY EVENING. SO EARLIER ADDITION OF CHANCE POPS
TO PARTS OF NW LOWER MI STILL LOOKS VERY REASONABLE. WILL REMOVE A
MENTION OF MIX OVER THE HIGHER TERRAIN (CAD AREA)...WHERE SNOW
SHOULD PREVAIL IF PRECIP DEVELOPS. CLOSER TO LAKE MI (MBL/FKS)...A
RA/SN MENTION IS GOOD. PLENTY OF CLOUDS FOR MOST...COULD BE SOME
THIN SPOTS EARLY IN NE LOWER BEFORE MID/HIGH CLOUDS THICKEN. MAX
TEMPS IN THE 30S.
TUE NIGHT/WEDNESDAY...WARM ADVECTION/FGEN BAND OF MID-LEVEL MOISTURE
WILL CONTINUE TO LIFT ACROSS THE FORECAST AREA TUE NIGHT.
HOWEVER...LIFT WILL WEAKEN WITH TIME...ESPECIALLY OVERNIGHT...AS THE
WEAK SURFACE LOW REACHES LAKE ERIE AND FILLS. SMALL CHANCE POPS ARE
STILL REASONABLE FOR MUCH OF NORTHERN LOWER MI TUE EVENING (STILL
HOLDING ONTO A MIX IN COASTAL AREAS)...BUT SLIGHT CHANCE OR LESS
WILL SUFFICE BY THE TIME THE BAND LIFTS ACROSS EASTERN UPPER/FAR NE
LOWER MI OVERNIGHT. STRATUS SHOULD BE CONSIDERABLE BEHIND THE
DEPARTING BAND...BUT THERE MAY SOME BREAKS IN THE FAR SE. HIGH
PRESSURE MAKES A BRIEF RETURN WED MORNING...THEN SHUNTS EAST AS LOW
PRESSURE DEEPENS IN OK. PRECIP MAY START TO BREAK OUT IN
IOWA/NORTHERN IL DURING THE DAY...BUT NOT THIS FAR NE. IF WE GET
LUCKY...WE COULD SEE SOME BRIEF PERIODS OF SUN AS LOW LEVEL MOISTURE
GETS INCREASINGLY THIN...BUT MID/HIGH CLOUD WILL BE ON THE INCREASE
LATE.
MIN TEMPS ABOVE GUIDANCE GIVEN ABUNDANT CLOUDS...MID 20S TO LOWER
30S. MAX TEMPS MID 30S TO NEAR 40F.
REST OF THE FORECAST...YESTERDAYS TIGHTLY-CLUSTERED SOLUTIONS WERE
DESTINED NOT TO REPEAT. THE DAY SHIFT NOTED A TREND TOWARD A LESS
AMPLIFIED AND MORE SOUTHERLY TRACK FOR THE LOW FORECAST TO CROSS THE
LAKES REGION LATE THURSDAY. TONIGHT...WE/VE MOVED BACK TO A MEAN
THAT LOOKS SIMILAR TO LAST NIGHT...THOUGH WITH MORE IN THE WAY OF
MODEL SPREAD. THEY (AND I) CONTINUE TO STRUGGLE A BIT WITH COMPETING
ELEMENTS. WE HAVE A TON OF ENERGY POURING INTO THE PAC COAST TO PUSH
THINGS ALONG...AND A WEAK BLOCKING RIDGE OVER FAR EASTERN CANADA.
THE BLOCK IS NOT IMPRESSIVE AND WILL BE DISLODGED...BUT HOW QUICKLY?
THE INCOMING UPPER TROF TAKES ON A NEGATIVE TILT...BUT OVERALL THE
PATTERN IS QUITE PROGRESSIVE AND NOT HIGHLY AMPLIFIED. HOW MUCH WILL
THE SYSTEM WRAP UP...SLOW DOWN...AND GET TUGGED NW (IF AT ALL)?
THE NAM AND DGEX REPRESENT DEEPER AND MORE NORTHERLY TRACKS THAT
WOULD BE MORE RAIN AND LESS SNOW FOR US. 00Z ECMWF OFFERS THE MOST
SOUTHERLY...SNOWIEST SOLUTION. GFS/GEM ARE SOMEWHERE IN BETWEEN...
THOUGH WITH THE GEM SLOWER THAN THE REST OF THE MODELS. SOME SORT OF
GEM/GFS/ECMWF MISH-MASH IS MOST APPROPRIATE...AS WE STILL HAVE TIME
TO SEE HOW THE DETAILS FALL OUT.
PRECIP SHOULD ARRIVE IN SW SECTIONS OVERNIGHT WED NIGHT...MAINLY AS
SNOW. A TRACK ACROSS CENTRAL LOWER MI LATE THURSDAY WILL OPEN UP AT
LEAST THE SE HALF OF THE FORECAST AREA TO MIX WITH/TURN TO RAIN.
WINDY/SNOWY CONDITIONS LATE THURSDAY NIGHT INTO FRIDAY AS SYSTEM
DEPARTS. POTENTIAL FOR SUBSTANTIAL LAKE ENHANCEMENT...BUT VERY
DIFFICULT TO ANSWER THE FETCH QUESTION YET GIVEN MODEL DIFFS. WILL
TRY TO ADD A FEW DETAILS TO THE HAZ WX OUTLOOK. COLDER TEMPS (NEAR
CLIMO) OVER THE WEEKEND...WITH DECREASING CHANCES FOR LAKE EFFECT AS
SURFACE RIDGING TRIES TO EDGE EAST.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 633 AM EST MON DEC 17 2012
MVFR CIGS WILL REMAIN OVER ALL TAF SITES THROUGH THE TAF
PERIOD...AS SLIGHTLY DRIER AIR MOVES IN AND SURFACE LOW MOVES INTO
ONTARIO AND WEAKENS. LITTLE TO NO CHANCE THAT THE CLOUD DECK WILL
SCOUR OUT TONIGHT WITH MFVR CLOUDS EXTENDING ALL THROUGH THE
WESTERN GREAT LAKES INTO THE NORTHERN PLAINS...WITH WEAK WINDS AND
NO SIGNIFICANT AIR MASS CHANGE FURTHER HELPING TO KEEP CLOUDS IN
PLACE. WE WILL SEE SOME NUISANCE LAKE EFFECT -SHRA OR -SHSN
ACROSS APN/PLN/TVC TODAY...BUT NOTHING THAT WILL CREATE PROBLEMS
IN TERMS OF RESTRICTING VSBY`S.
&&
.MARINE...
ISSUED AT 315 AM EST MON DEC 17 2012
LIGHT WINDS AND LOW WAVES ARE EXPECTED AS WE HEAD INTO THE MID WEEK
PERIOD...AS WEAK LOW PRESSURE DRIFTS OUT OF THE REGION TODAY...ONLY
TO BE REPLACED BY HIGH PRESSURE THROUGH AT LEAST WEDNESDAY EVENING.
THE ONE EXCEPTION WILL BE TODAY...AS SLIGHTLY STRONGER WINDS WILL BE
FOUND ACROSS THE WATERS (STILL LESS THAN 20 KNOTS) AS COOLER AIR
FILTERS INTO THE REGION. AFTER THAT...STRONG LOW PRESSURE IS
EXPECTED TO TRACK THROUGH THE REGION WEDNESDAY NIGHT THROUGH
FRIDAY...USHERING IN A PERIOD OF MUCH STRONGER WINDS...WITH GALE
FORCE GUSTS VERY POSSIBLE. WIDESPREAD RAIN AND/OR SNOW IS ALSO
EXPECTED TO ACCOMPANY THIS SYSTEM...WITH LAKE EFFECT SNOW SHOWERS
AND CONTINUED GUSTY CONDITIONS LIKELY FOR THE WEEKEND.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...MB
SYNOPSIS...JZ
SHORT TERM...LAWRENCE
LONG TERM...JZ
AVIATION...NS
MARINE...LAWRENCE
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
933 AM CST MON DEC 17 2012
.UPDATE...
ISSUED AT 928 AM CST MON DEC 17 2012
HAVE BEEN GETTING REPORTS OF SOME LIGHT SNOW ACCUMULATION WITHIN
THE PRECIPITATION BAND THAT CURRENTLY EXTENDS FROM MEXICO TO
PITTSFIELD. THIS IS COINCIDENT WITH A BAND OF MID-LEVEL FRONTOGENESIS
DEPICTED BY THE RAP THAT WILL SINK SOUTH AND DECREASE IN INTENSITY.
FOR NOW HAVE ADDED WINTRY MIX WORDING TO THE NORTHERN THIRD OF THE
CWA WITH SOME MINOR SNOW ACCUMULATIONS. HAVE STUCK WITH JUST RAIN
IN THE FORECAST THIS AFTERNOON AS RAP SOUNDINGS ARE SHOWING A
SLIGHTLY WARMER BOUNDARY LAYER. ALSO LOWERED TEMPERATURES OVER THE
NORTHERN PART OF THE CWA TODAY GIVEN THE PRECIPITATION AND CLOUDS.
BRITT
&&
.SHORT TERM...
ISSUED AT 322 AM CST MON DEC 17 2012
(TODAY THROUGH TUESDAY NIGHT)
THE COLD FRONT WHICH PASSED SOUTH OF OUR AREA YESTERDAY HAS STALLED
OVER NORTHEAST ARKANSAS...THE MISSOURI BOOT HEEL AND EXTREME
SOUTHERN ILLINOIS THIS MORNING. ALOFT...A DEEPENING SHORTWAVE IS
MOVING EAST FROM THE GREAT PLAINS INTO WESTERN MISSOURI. THE
SHORTWAVE WILL CONTINUE MOVING EAST TODAY AND INTERACT WITH A
RELATIVELY SHALLOW LAYER OF LOW LEVEL MOISTURE. RADAR OVER
SOUTHEAST KANSAS SHOWS A COUPLE OF BANDS OF LIGHT RAIN MOVING EAST
NORTHEAST. EXPECT THESE BANDS TO CONTINUE MOVING EAST WITH THE
SHORTWAVE TODAY...PERHAPS EXPANDING IN AREAL COVERAGE AS THE WAVE
ENCOUNTERS THE SOMEWHAT DEEPER MOISTURE IN PLACE OVER OUR AREA.
HAVE INCREASED POPS A BIT TO SHOW THIS...HOWEVER...ANY PRECIP THAT
DOES FALL SHOULD BE VERY LIGHT AND MAY NOT MEASURE. TEMPS SHOULD BE
COOLER TODAY ACROSS THE SOUTHERN 1/2 OF THE CWFA BEHIND THE
FRONT...ESPECIALLY IF THERE`S PRECIP IN THE AREA. TEMPS BEHIND THE
FRONT YESTERDAY WERE GENERALLY IN THE LOW TO MID 40S...SO GUIDANCE
TEMPS LOOKED PRETTY REASONABLE.
UPPER LEVEL RIDGE BUILDS OVER THE REGION LATE TONIGHT INTO TUESDAY
WHICH DIVERTS ANOTHER SHORTWAVE TO OUR NORTH. HOWEVER...THE WAVE
TURNS OUR LOW LEVEL FLOW BACK AROUND TO THE SOUTHWEST WHICH QUICKLY
BRINGS WARMER AIR BACK INTO THE MID-MISSISSIPPI VALLEY. FORECAST
SOUNDINGS ARE INDICATING A RELATIVELY CLOUD-FREE DAY AS WELL UNDER
THE UPPER RIDGE...SO EXPECT WARMING BACK INTO THE 50S...NEAR 60 IN
CENTRAL MO. WILL SEE INCREASING HIGH CLOUDS TUESDAY NIGHT AHEAD OF
THE NEXT STORM SYSTEM...THAT AND PERSISTENT SOUTHERLY FLOW OVER MUCH
OF THE AREA SHOULD KEEP TEMPS RELATIVELY MILD IN THE MID TO UPPER
30S.
CARNEY
&&
.LONG TERM...
ISSUED AT 322 AM CST MON DEC 17 2012
(WEDNESDAY THROUGH SUNDAY)
PRIMARY FOCUS CONTINUES TO BE STRONG STORM DEVELOPING WEDNESDAY OVER
THE PLAINS AND MOVING INTO THE MIDWEST WEDNESDAY NIGHT. MODEL
SOLUTIONS ARE...IF ANYTHING...LESS CERTAIN THAN THEY WERE
YESTERDAY. EACH ONE SEEMS TO HAVE A DIFFERENT TRACK FOR THE STORM.
NAM...GFS...AND GEM TAKE THE SURFACE AND 850MB LOW WELL NORTH OF ST.
LOUIS...WHILE THE ECMWF MOVES THE LOW ALMOST DIRECTLY OVER THE METRO
AREA...AND IS ABOUT 6HRS SLOWER IN ITS EASTWARD PROGRESSION OF THE
STORM THAN THE OTHER MODELS. OBVIOUSLY THE SLOWER/MORE SOUTHERN
ECMWF IS MORE FAVORABLE FOR SNOW IN NORTHERN PORTIONS OF THE CWFA.
IT`S ALSO MORE CONSISTENT WITH PREVIOUS MODEL RUNS...SO HAVE LEANED
IN THIS DIRECTION. IF YOU BELIEVE THE ECMWF VERBATIM...RAIN AND
THUNDERSTORMS WILL BE THE RULE ACROSS THE ENTIRE AREA AT LEAST
THROUGH MIDNIGHT...PROBABLY UNTIL SOMETIME BETWEEN 09Z AND 12Z
THURSDAY MORNING. SHOULD SEE PRECIP CHANGE OVER RAPIDLY ACROSS THE
AREA FROM 12Z THROUGH 18Z THURSDAY AS COLD AIR WRAPS AROUND THE
LOW. THE VAST MAJORITY OF THE AREA PROBABLY WON`T EVEN SEE A
DUSTING IN THIS SCENARIO...HOWEVER PARTS OF NORTHEAST MISSOURI AND
WEST CENTRAL ILLINOIS COULD SEE SOME LIGHT ACCUMULATIONS. THE OTHER
BIG IMPACT OF THIS STORM LOOKS TO BE WIND. FORECAST SOUNDINGS ARE
SHOWING WIND GUSTS IN EXCESS OF 35KTS. WILL HAVE TO KEEP AN EYE ON
THIS FOR A POTENTIAL WIND ADVISORY.
REMAINDER OF THE FORECAST LOOKS PRETTY QUIET WITH QUASI-ZONAL FLOW
ALOFT BEHIND THE STORM. LOOKS LIKE TEMPERATURES WILL BE SEASONABLY
COOL FOR FRIDAY AND SATURDAY...WITH COOLING TEMPS ON SUNDAY AS THE
FLOW AMPLIFIES WITH LOW PRESSURE OVER THE EAST COAST PUSHING COLD
CANADIAN AIR SOUTH THROUGH THE MISSISSIPPI VALLEY.
CARNEY
&&
.AVIATION...
ISSUED AT 513 AM CST MON DEC 17 2012
LOW PRESSURE MOVING ALONG A STALLED FRONTAL BOUNDARY TO OUR SOUTH
WILL INSURE IFR CONDITIONS AND SCATTERED SHOWERS THIS MORNING
ALONG AND SOUTH OF I-7O. CEILING AND VISIBILITY TO RISE BACK TO
MVFR CONDITIONS LATER THIS AFTERNOON FROM WEST TO EAST AS THE WEAK
STORM SYSTEM EXITS TO THE EAST. STRATUS WILL EVENTUALLY LIFT NORTH
AND EAST OF THE CWA TONIGHT LOW LEVEL FLOW BECOMES SOUTHERLY.
SPECIFICS FOR KSTL...
IFR CONDITIONS ARE EXPECTED THIS MORNING WITH SCATTERED SHOWERS AS
AREA OF LOW PRESSURE PASSES TO THE SOUTHEAST OF THE TERMINAL. WIND
TO VEER FROM NORTH TO NORTHWEST TODAY AND EVENTUALLY TO THE SOUTH
TONIGHT. STRATUS WILL BE SLOW TO CLEAR UNTIL WIND BECOMES
SOUTHERLY AND ADVECTS IT TO THE NORTHEAST. HAVE THEREFORE PUSHED
CLEARING TO LATE TONIGHT.
CVKING
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
527 AM CST MON DEC 17 2012
.AVIATION...12Z KGRI TAF. VFR CONDITIONS EXPECTED THROUGH MUCH OF
THE TAF PERIOD...WITH LIFR CONDITIONS NOT OUT OF THE QUESTION FOR
A TIME THIS MORNING. BIGGEST CONCERN WITHIN THE NEXT SIX HOURS IS
AN AREA OF STRATUS...CURRENTLY NEAR KODX AND KBVN...MOVING
SOUTHEAST AT AROUND 20KTS. GIVEN THE CURRENT MOVEMENT OF THIS
STRATUS DECK...THE EXTREME WESTERN PERIPHERY COULD CLIP KGRI
STARTING AROUND 14Z. IF THE PATH OF THIS DECK SHIFTS SLIGHTLY TO
THE EAST...OR IF THE WESTERN EDGE OF THIS DECK ERODES
SOMEWHAT...THEN KGRI COULD ESCAPE WITH VFR CONDITIONS THROUGHOUT
THE TAF PERIOD. THERE ARE NOT HOWEVER ANY SUCH INDICATIONS OF THIS
DECK CHANGING PATH FOR ERODING AND GIVEN THIS...OPTED TO GO WITH
TEMPO LIFR CEILINGS AT KGRI 14-17Z. ASSUMING THE STRATUS CLEARS
THE AREA BY MIDDAY...MID LEVEL CLOUDS WITH CEILINGS NEAR 8000FT
AGL SHOULD BE ALL THAT IS LEFT TO CONTEND WITH THROUGH THE
REMAINDER OF THE TAF PERIOD. THE SURFACE WIND WILL VARY FROM THE
WEST/NORTHWEST TO THE SOUTHWEST THROUGH THE TAF PERIOD...AND
VISIBILITY RESTRICTIONS ARE NOT CURRENTLY EXPECTED THROUGH THE
NEXT 24 HOURS.
&&
.PREV DISCUSSION... /ISSUED 516 AM CST MON DEC 17 2012/
SHORT TERM...THROUGH WEDNESDAY NIGHT. THE PRIMARY CONCERN DURING
THE NEXT 72 HOURS CONTINUES TO BE STILL APPEARS TO BE OUR FIRST
WIDESPREAD ACCUMULATING SNOW/BLOWING SNOW EVENT OF THE SEASON WED
INTO WED NIGHT. OVERALL LITTLE HAS CHANGED IN PREVIOUS
THINKING...AS CONFIDENCE IS FAIRLY HIGH THAT HEADLINE-WORTHY
CONDITIONS FEATURING AT LEAST A FEW INCHES OF SNOW AND PLENTY OF
WIND BE REALIZED FOR MOST IF NOT ALL OF THE AREA...BUT THE DETAILS
REGARDING TOTAL ACCUMULATION POTENTIAL ARE STILL UNCERTAIN...AND
CAUTION IS ADVISED AGAINST TAKING THE CURRENT SNOWFALL FORECAST
TOO LITERALLY JUST YET AS THE SYSTEM IS STILL WELL OUT OVER THE
PACIFIC.
STARTING OFF AT 09Z THIS MORNING...THERE ARE A FEW PESKY ISSUES TO
CONSIDER WELL BEFORE THE WED STORM ARRIVES. OBJECTIVE SURFACE
ANALYSIS FEATURES A WEAKISH 1007MB LOW OVER THE FAR NORTHERN
CWA...WITH A VERY SUBTLE TROUGH AXIS TRAILING SOUTH NEAR THE
HIGHWAY 281 CORRIDOR...DOING LITTLE MORE THAN SEPARATING A LIGHT
BUT STEADY WESTERLY BREEZE IN WESTERN COUNTIES...FROM SLIGHTLY
MORE SOUTHERLY LIGHT BREEZES IN THE EAST. TEMPS EARLY THIS
MORNING HAVE TRENDED A FEW DEGREES WARMER THAN EARLIER
FORECAST...WITH LOWS LIKELY ENDING UP IN THE MID 20S MOST
AREAS...EXCEPT FOR COLDER IN THE TYPICAL DAWSON/VALLEY COUNTIES
CORRIDOR. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA
REVEAL A MODEST MID LEVEL SHORTWAVE TROUGH AXIS TRACKING DIRECTLY
OVER THE CWA AT THIS HOUR...ALTHOUGH WITH THE MAJORITY OF UPWARD
FORCING ALREADY WELL OFF TO THE EAST...SKIES HAVE LARGELY CLEARED
BEHIND THIS UPPER TROUGH AXIS...WHICH ACTUALLY BROUGHT A NARROW
LINE OF LIGHT SLEET SHOWERS TO PRIMARILY THE SOUTHWESTERN 1/4 OF
THE CWA ON SUNDAY EVENING. UNFORTUNATELY...WHAT ORIGINALLY
APPEARED TO BE A FAIRLY STRAIGHTFORWARD SKY COVER FORECAST HAS
BEEN COMPLICATED BY A FAIRLY SOLID PROTRUSION OF VERY LOW STRATUS
THAT IS CURRENTLY SINKING SOUTH ACROSS NORTH CENTRAL
NEBRASKA...AND IS POISED TO OVERTAKE AT LEAST A FEW COUNTIES IN
THE CWA NORTH OF HIGHWAY 92 OVER THE NEXT FEW HOURS. THIS LOW
CLOUD DECK IS ALSO ASSOCIATED WITH AT LEAST PATCHY FOG WITH
VISIBILITY AROUND/UNDER 1 MILE.
FORECAST WISE...THE OBVIOUS VERY SHORT TERM ISSUE TODAY IS THE
AFOREMENTIONED LOW STRATUS JUST NOW MOVING INTO OUR FAR NORTHERN
COUNTIES...AS THIS WAS NOT WELL-ANTICIPATED BY MODELS AT ALL. THE
LATEST RAP RUNS HAVE FINALLY CAUGHT ONTO IT SOMEWHAT PER THE
950-925MB RELATIVE HUMIDITY FIELDS...AND THUS THE GENERAL
EXPECTATION IS THAT THIS STRATUS AND ASSOCIATED FOG WILL IN FACT
INVADE ROUGHLY THE 5 NORTHEASTERN-MOST COUNTIES SUCH AS
NANCE/GREELEY OVER THE NEXT FEW HOURS...AND POSSIBLY HANG AROUND
WELL INTO THE DAYLIGHT HOURS BEFORE FINALLY PUSHING OUT TO THE
NORTHEAST BY EARLY-MID AFTERNOON. ALTHOUGH THIS STRATUS IS
CURRENTLY NOT EXPECTED TO SINK AS FAR SOUTHWEST AS GRAND
ISLAND/HASTINGS...THIS WILL BEAR WATCHING AS IT COULD GET SOMEWHAT
CLOSE. ALTHOUGH AM CURRENTLY NOT AWARE OF ANY DENSE FOG ASSOCIATED
WITH THIS STRATUS DECK...CURRENTLY HAVE PATCHY FOG IN THE GRIDS
THROUGH 15Z IN BOTH THE NORTHEASTERN AND FAR SOUTHERN CWA...WITH
THE LATTER ASSOCIATED WITH A COMPLETELY SEPARATE AREA OF LOW
STRATUS BARELY SKIRTING SOUTH OF THE AREA ACROSS CENTRAL KS.
MOVING ON TO OTHER ELEMENTS OF TODAY/S FORECAST...THOSE AREAS THAT
DON/T GET SOCKED IN SHOULD REALIZE QUITE A BIT OF SUNSHINE
TODAY...ALTHOUGH AT LEAST THIN MID/HIGH CLOUDS WILL BE ON THE
INCREASE FROM THE WEST THIS AFTERNOON AHEAD OF THE NEXT VERY
SUBTLE MID LEVEL WAVE. AT THE SURFACE...LOW PRESSURE DEVELOPING
ALONG AN AXIS FROM MT TO NORTHWEST NEB TODAY WILL GRADUALLY TURN
BREEZES MORE SOUTHERLY...WITH SUSTAINED SPEEDS AT LEAST 10-15 MPH
IN MOST AREAS WITH SOME HIGHER GUSTS. RAISED HIGHS TEMPS 1-3
DEGREES FROM PREVIOUS FORECAST IN SOME AREAS...BUT OVERALL SIMILAR
TO PREVIOUS WITH MOST NEB ZONES MID-UPPER 40S AND KS ZONES MAINLY
LOW-MID 50S.
TONIGHT...THE NEXT MID LEVEL SHORTWAVE TROUGH WILL TRACK PRIMARILY
ACROSS THE NORTHERN 1/2 OF NEB...WITH ISENTROPIC LIFT AHEAD OF
THIS WAVE POSSIBLY SPARKING SOME FLURRIES OR LIGHT ACCUMULATING
SNOW WITHIN 100 MILES OR SO NORTH/NORTHEAST OF THE CWA...BUT AM
NOT FORECASTING ANY SNOW TO AFFECT OUR LOCAL AREA AT THIS TIME. A
SURFACE LOW ASSOCIATED WITH THIS WAVE WILL TRACK ACROSS NORTHERN
NEB THROUGH THE NIGHT...SIMILAR TO THE ONE THIS MORNING EXCEPT
STRONGER. THIS WILL INDUCE A NOTICEABLY WESTERLY BREEZE
OVERNIGHT...WITH SUSTAINED SPEEDS LIKELY NEAR OR EXCEEDING 15 MPH
FOR AT LEAST A FEW HOURS. DESPITE MOSTLY CLEAR SKIES...THESE WEST
WINDS SHOULD HELP HOLD TEMPS UP FAIRLY EFFICIENTLY. MADE LITTLE
CHANGE TO LOW TEMPS...KEEPING THEM PRIMARILY MID 20S...BUT WOULD
NOT BE SURPRISED TO SEE SOME AREAS HOLD UP CLOSER TO 30.
TUESDAY LOOKS TO BE A FAIRLY TRANQUIL/MILD DAY AHEAD OF THE
APPROACHING PRIMARY STORM SYSTEM...WHICH WILL FINALLY BE COMING
ONSHORE IN SOUTHERN CAL. MEANWHILE...SUBTLE SHORTWAVE RIDING WILL
DOMINATE THE CENTRAL PLAINS ALOFT...WHILE AT THE
SURFACE...FAIRLY LIGHT BUT STEADY WESTERLY BREEZES WILL PREVAIL IN
THE WAKE OF THE LOW DEPARTING EAST TOWARD THE LOWER GREAT LAKES.
MADE VERY LITTLE CHANGE TO HIGHS...AS THIS SHOULD BE THE MILDEST
DAY OF THE WEEK IN MOST AREAS AND AM AIMING FOR UPPER 40S
NORTH/NEAR 50 TRI-CITIES AND MID-UPPER 50S KS ZONES.
TUES NIGHT...IT REMAIN PRECIP FREE ACROSS THE CWA...ALTHOUGH
CHANGES WILL GET UNDERWAY AS EAST-NORTHEAST SURFACE WINDS RAMP UP
TO 15+ MPH AS THE NIGHT GOES ON...IN RESPONSE TO CYCLOGENESIS
TAKING PLACE IN THE SOUTHEAST CO/OK PANHANDLE AREA. ALOFT...THERE
IS GOOD MODEL CONSENSUS AMONGST THE NAM/GFS/ECMWF THAT THE
POWERFUL SHORTWAVE AXIS WILL BE NEAR THE 4-CORNERS AT 12Z WED
MORNING. FOR LOW TEMPS...ALMOST NO CHANGE WITH UPPER 20S/LOW 30S.
LAST BUT CERTAINLY NOT LEAST...THE WEDNESDAY INTO WED NIGHT
PERIODS PROMISE TO BE QUITE ACTIVE...BUT AS STATED AT THE
TOP...THE DETAILS REGARDING SNOW ACCUMULATIONS ARE STILL A BIT
SKETCHY. IN SHORT...MODEL CONSENSUS ON THE TRACK OF THE UPPER WAVE
IS PRETTY DECENT...AS IT MIGRATES FROM THE 4-CORNERS REGION AT
SUNRISE WEDNESDAY...TO OVER THE HEART OF NEB/KS EARLY WED
EVENING...TO SOMEWHERE OVER IA/MO BY SUNRISE THURS MORNING. THE
NAM HAS BEEN A BIT OF AN OUTLIER VERSUS OTHER MODELS IN
INTENSIFYING/CLOSING OFF THE 500MB CIRCULATION DIRECTLY OVER THE
CWA AS THE WAVE PASSES...WHICH IN TURN RESULTS IN SOME FAIRLY
CONCERNING MODEL-GENERATED SNOW AMOUNTS IN EXCESS OF 6 INCHES
MAINLY NORTH OF I-80. HOWEVER...BOTH THE GFS/ECMWF MAINTAIN A BIT
MORE SOUTHERN TRACK OF THE SYSTEM...TAKING THE PRIMARY SURFACE LOW
GENERALLY ACROSS THE OK/KS BORDER INTO CENTRAL MO...VERSUS THE NAM
WHICH TAKES THE SURFACE LOW MORE OVER THE KC METRO AREA. THIS
TRACK WILL OBVIOUSLY PROVE CRITICAL AS TO WHETHER THE NORTHERN 1/2
OR SOUTHERN 1/2 OF THE CWA WILL REALIZE THE MOST SNOW...AND FOR
NOW HAVE GENERALLY USED A BLEND OF MODEL SOLUTIONS FOR THIS
MORNING/S FORECAST...WHICH RESULTS IN A VERY ROUGH STORM TOTAL
SNOW FORECAST OF 2-4 INCHES CWA-WIDE. CERTAINLY IT IS POSSIBLE
THAT SOME AREAS COULD SEE MORE THAN THIS...BUT UNTIL THE TRACK
BECOMES A BIT CLEARER IT WOULD NOT BE WISE TO TRY PINPOINTING
HIGHER THAN THIS. ALTHOUGH THIS IS A FAIRLY PROGRESSIVE
SYSTEM...IT WILL HAVE QUITE A BIT GOING FOR IT IN TERMS OF STRONG
UPPER JET DIVERGENCE AND ASSOCIATED MID LEVEL
FRONTOGENESIS/DEFORMATION. TIMING-WISE...THE GENERAL EXPECTATION
IS THAT SNOW WILL FIRST BREAK OUT MAINLY ACROSS THE NORTHWEST 1/3
OF THE CWA/NORTHWEST OF THE TRI-CITIES/DURING THE MORNING
HOURS...AND THEN RAPIDLY EXPAND ACROSS THE REMAINDER OF THE AREA
WED AFTERNOON INTO WED EVENING...WHILE AT THE SAME TIME SUSTAINED
SPEEDS WILL RAMP UP INTO THE 20-30 MPH RANGE WITH GUSTS TO AROUND
40 MPH...FIRST FROM THE NORTHEAST AND THEN SWINGING AROUND TO THE
NORTHWEST BY EVENING. VISIBILITY RESTRICTIONS WILL BE AN ISSUE FOR
SURE...BUT NOT THINKING BLIZZARD CRITERIA OF WIDESPREAD 1/4 MILE
OR LESS AT THIS POINT. LIKELY 60-70 POPS ARE IN PLACE FOR MUCH OF
THE CWA DURING THE AFTERNOON/EVENING HOURS...AND THESE WILL LIKELY
BE RAISED FURTHER OVER THE NEXT FEW DAYS. AFTER
MIDNIGHT...LINGERED SOME 20-30 POPS WITHIN THE EASTERN 1/2 OF THE
CWA...BUT THE VAST MAJORITY OF ACCUMULATIONS SHOULD BE DONE BY
THEN...AND CERTAINLY SHOULD BE OVER WITH WELL BEFORE SUNRISE.
WINDS SHOULD ALSO DIMINISH SOMEWHAT PRIOR TO SUNRISE...RESULTING
IN IMPROVING VISIBILITIES IN ANY BLOWING SNOW. TEMPS ON WED WILL
ESSENTIALLY RISE VERY LITTLE IF ANY FROM OVERNIGHT LOWS...AND KEPT
HIGHS IN THE LOW 30S EXCEPT IN THE FAR SOUTHEAST...WHERE UPPER 30S
COULD BE ATTAINABLE. ALTHOUGH NOT EXPECTING MUCH OF AN ISSUE WITH
SLEET/FREEZING RAIN WITH THIS SYSTEM...WILL HAVE TO WATCH FAR
SOUTHEAST AREAS AROUND BELOIT KS AS THINGS FIRST GET UNDERWAY...AS
TEMPS ALOFT COULD BE JUST WARM ENOUGH FOR A BRIEF WINTRY MIX
BEFORE AN OUTRIGHT CHANGEOVER TO SNOW. FOR NOW THOUGH...HAVE KEPT
ALL MENTION OF MIXED-PHASE OUT OF THE GRIDS.
LONG TERM...STARTING 12Z THURSDAY. GUIDANCE FROM THE
EC...OPERATIONAL GFS AND GEFS-MEAN ALL SUGGEST MID AND UPPER LEVEL
RIDGING WILL PERSIST OVER THE CENTRAL CONUS THROUGHOUT THE LONG
TERM FORECAST PERIOD. THE OVERALL LACK IN KINEMATIC FORCING SHOULD
PRESENT DRY CONDITIONS AS A RESULT. GUIDANCE FROM THE EC AND
OPERATIONAL GFS SUGGEST THE DEPARTING STORM SYSTEM TO OUR EAST
WILL PROVIDE A STIFF NORTHWEST WIND TO OUR AREA THROUGH MUCH OF
THURSDAY. THE INCREASING POTENTIAL FOR FRESH SNOW PACK ACROSS THE
AREA...WORKING IN CONCERT WITH LOW LEVEL COLD AIR
ADVECTION...MEANS TEMPERATURES WILL PROBABLY HAVE DIFFICULTY
CLIMBING ALL THAT FAR ON THURSDAY. GIVEN THIS...WENT AHEAD AND
UNDERCUT ALLBLEND BY 2-3 DEGREES FOR MANY LOCATIONS ACROSS THE CWA
WHICH PRESENTS HIGHS IN THE LOW 30S FOR THE MOST PART. THERE IS A
CHANCE THURSDAY HIGH TEMPERATURES WILL NEED TO BE DECREASED MORE
IN THE COMING DAYS SHOULD THE ANTICIPATED SNOWFALL MATERIALIZE ON
WEDNESDAY. CLEAR SKIES AND A DECREASING LOW LEVEL WIND
FIELD...ALONG WITH A FEW INCHES OF SNOW ON THE GROUND...WILL
LIKELY PRESENT A COLD NIGHT THURSDAY NIGHT. ~30 DEGREE TEMPERATURE
DROP-OFFS DO NOT SEEM UNREASONABLE GIVEN THE EXPECTED SYNOPTIC
SETUP...WHICH WOULD PROVIDE OVERNIGHT LOWS GENERALLY IN THE LOW
TEENS. ALLBLEND ONLY PROVIDE LOWS IN THE MID TO UPPER TEENS AND AS
A RESULT...WENT AHEAD AND UNDERCUT ALLBLEND BY A COUPLE DEGREES
BUT MUCH LIKE THE HIGHS ON THURSDAY...THERE IS A POSSIBILITY THAT
THURSDAY NIGHT LOWS WILL NEED TO BE DECREASED A BIT MORE IN THE
COMING DAYS. A PERSISTENT WESTERLY COMPONENT TO THE LOW LEVEL WIND
FIELD...ALONG WITH MODEST LOW LEVEL WARM AIR ADVECTION...SHOULD
HELP THE SNOW PACK ERODE QUITE A BIT HEADING INTO FRIDAY...WITH A
RESULTANT WARMING TREND EXPECTED. NO REAL REASON TO DISAGREE WITH
ALLBLEND WHICH PRESENTED AFTERNOON HIGHS IN THE 30S AND 40S AND
FRIDAY NIGHT LOWS IN THE MID TO UPPER TEENS. THERE ARE INDICATIONS
FROM THE EC AND OPERATIONAL GFS OF A BACKDOOR COLD FRONT PUSHING
ACROSS THE AREA HEADING INTO THE DAY SATURDAY...WITH ALLBLEND
PRESENTING A SUBTLE COOLING TREND TO FINISH THE LONG TERM FORECAST
PERIOD. NO REASON TO DISAGREE WITH ALLBLEND SO LEFT SUNDAY HIGH
TEMPERATURE IN THE 30S FOR MOST LOCATIONS ACROSS THE CWA.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...PFANNKUCH
AVIATION/LONG TERM...BRYANT
AREA FORECAST DISCUSSION
NWS HASTINGS NE
516 AM CST MON DEC 17 2012
.SHORT TERM...THROUGH WEDNESDAY NIGHT. THE PRIMARY CONCERN DURING
THE NEXT 72 HOURS CONTINUES TO BE STILL APPEARS TO BE OUR FIRST
WIDESPREAD ACCUMULATING SNOW/BLOWING SNOW EVENT OF THE SEASON WED
INTO WED NIGHT. OVERALL LITTLE HAS CHANGED IN PREVIOUS
THINKING...AS CONFIDENCE IS FAIRLY HIGH THAT HEADLINE-WORTHY
CONDITIONS FEATURING AT LEAST A FEW INCHES OF SNOW AND PLENTY OF
WIND BE REALIZED FOR MOST IF NOT ALL OF THE AREA...BUT THE DETAILS
REGARDING TOTAL ACCUMULATION POTENTIAL ARE STILL UNCERTAIN...AND
CAUTION IS ADVISED AGAINST TAKING THE CURRENT SNOWFALL FORECAST
TOO LITERALLY JUST YET AS THE SYSTEM IS STILL WELL OUT OVER THE
PACIFIC.
STARTING OFF AT 09Z THIS MORNING...THERE ARE A FEW PESKY ISSUES TO
CONSIDER WELL BEFORE THE WED STORM ARRIVES. OBJECTIVE SURFACE
ANALYSIS FEATURES A WEAKISH 1007MB LOW OVER THE FAR NORTHERN
CWA...WITH A VERY SUBTLE TROUGH AXIS TRAILING SOUTH NEAR THE
HIGHWAY 281 CORRIDOR...DOING LITTLE MORE THAN SEPARATING A LIGHT
BUT STEADY WESTERLY BREEZE IN WESTERN COUNTIES...FROM SLIGHTLY
MORE SOUTHERLY LIGHT BREEZES IN THE EAST. TEMPS EARLY THIS
MORNING HAVE TRENDED A FEW DEGREES WARMER THAN EARLIER
FORECAST...WITH LOWS LIKELY ENDING UP IN THE MID 20S MOST
AREAS...EXCEPT FOR COLDER IN THE TYPICAL DAWSON/VALLEY COUNTIES
CORRIDOR. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA
REVEAL A MODEST MID LEVEL SHORTWAVE TROUGH AXIS TRACKING DIRECTLY
OVER THE CWA AT THIS HOUR...ALTHOUGH WITH THE MAJORITY OF UPWARD
FORCING ALREADY WELL OFF TO THE EAST...SKIES HAVE LARGELY CLEARED
BEHIND THIS UPPER TROUGH AXIS...WHICH ACTUALLY BROUGHT A NARROW
LINE OF LIGHT SLEET SHOWERS TO PRIMARILY THE SOUTHWESTERN 1/4 OF
THE CWA ON SUNDAY EVENING. UNFORTUNATELY...WHAT ORIGINALLY
APPEARED TO BE A FAIRLY STRAIGHTFORWARD SKY COVER FORECAST HAS
BEEN COMPLICATED BY A FAIRLY SOLID PROTRUSION OF VERY LOW STRATUS
THAT IS CURRENTLY SINKING SOUTH ACROSS NORTH CENTRAL
NEBRASKA...AND IS POISED TO OVERTAKE AT LEAST A FEW COUNTIES IN
THE CWA NORTH OF HIGHWAY 92 OVER THE NEXT FEW HOURS. THIS LOW
CLOUD DECK IS ALSO ASSOCIATED WITH AT LEAST PATCHY FOG WITH
VISIBILITY AROUND/UNDER 1 MILE.
FORECAST WISE...THE OBVIOUS VERY SHORT TERM ISSUE TODAY IS THE
AFOREMENTIONED LOW STRATUS JUST NOW MOVING INTO OUR FAR NORTHERN
COUNTIES...AS THIS WAS NOT WELL-ANTICIPATED BY MODELS AT ALL. THE
LATEST RAP RUNS HAVE FINALLY CAUGHT ONTO IT SOMEWHAT PER THE
950-925MB RELATIVE HUMIDITY FIELDS...AND THUS THE GENERAL
EXPECTATION IS THAT THIS STRATUS AND ASSOCIATED FOG WILL IN FACT
INVADE ROUGHLY THE 5 NORTHEASTERN-MOST COUNTIES SUCH AS
NANCE/GREELEY OVER THE NEXT FEW HOURS...AND POSSIBLY HANG AROUND
WELL INTO THE DAYLIGHT HOURS BEFORE FINALLY PUSHING OUT TO THE
NORTHEAST BY EARLY-MID AFTERNOON. ALTHOUGH THIS STRATUS IS
CURRENTLY NOT EXPECTED TO SINK AS FAR SOUTHWEST AS GRAND
ISLAND/HASTINGS...THIS WILL BEAR WATCHING AS IT COULD GET SOMEWHAT
CLOSE. ALTHOUGH AM CURRENTLY NOT AWARE OF ANY DENSE FOG ASSOCIATED
WITH THIS STRATUS DECK...CURRENTLY HAVE PATCHY FOG IN THE GRIDS
THROUGH 15Z IN BOTH THE NORTHEASTERN AND FAR SOUTHERN CWA...WITH
THE LATTER ASSOCIATED WITH A COMPLETELY SEPARATE AREA OF LOW
STRATUS BARELY SKIRTING SOUTH OF THE AREA ACROSS CENTRAL KS.
MOVING ON TO OTHER ELEMENTS OF TODAY/S FORECAST...THOSE AREAS THAT
DON/T GET SOCKED IN SHOULD REALIZE QUITE A BIT OF SUNSHINE
TODAY...ALTHOUGH AT LEAST THIN MID/HIGH CLOUDS WILL BE ON THE
INCREASE FROM THE WEST THIS AFTERNOON AHEAD OF THE NEXT VERY
SUBTLE MID LEVEL WAVE. AT THE SURFACE...LOW PRESSURE DEVELOPING
ALONG AN AXIS FROM MT TO NORTHWEST NEB TODAY WILL GRADUALLY TURN
BREEZES MORE SOUTHERLY...WITH SUSTAINED SPEEDS AT LEAST 10-15 MPH
IN MOST AREAS WITH SOME HIGHER GUSTS. RAISED HIGHS TEMPS 1-3
DEGREES FROM PREVIOUS FORECAST IN SOME AREAS...BUT OVERALL SIMILAR
TO PREVIOUS WITH MOST NEB ZONES MID-UPPER 40S AND KS ZONES MAINLY
LOW-MID 50S.
TONIGHT...THE NEXT MID LEVEL SHORTWAVE TROUGH WILL TRACK PRIMARILY
ACROSS THE NORTHERN 1/2 OF NEB...WITH ISENTROPIC LIFT AHEAD OF
THIS WAVE POSSIBLY SPARKING SOME FLURRIES OR LIGHT ACCUMULATING
SNOW WITHIN 100 MILES OR SO NORTH/NORTHEAST OF THE CWA...BUT AM
NOT FORECASTING ANY SNOW TO AFFECT OUR LOCAL AREA AT THIS TIME. A
SURFACE LOW ASSOCIATED WITH THIS WAVE WILL TRACK ACROSS NORTHERN
NEB THROUGH THE NIGHT...SIMILAR TO THE ONE THIS MORNING EXCEPT
STRONGER. THIS WILL INDUCE A NOTICEABLY WESTERLY BREEZE
OVERNIGHT...WITH SUSTAINED SPEEDS LIKELY NEAR OR EXCEEDING 15 MPH
FOR AT LEAST A FEW HOURS. DESPITE MOSTLY CLEAR SKIES...THESE WEST
WINDS SHOULD HELP HOLD TEMPS UP FAIRLY EFFICIENTLY. MADE LITTLE
CHANGE TO LOW TEMPS...KEEPING THEM PRIMARILY MID 20S...BUT WOULD
NOT BE SURPRISED TO SEE SOME AREAS HOLD UP CLOSER TO 30.
TUESDAY LOOKS TO BE A FAIRLY TRANQUIL/MILD DAY AHEAD OF THE
APPROACHING PRIMARY STORM SYSTEM...WHICH WILL FINALLY BE COMING
ONSHORE IN SOUTHERN CAL. MEANWHILE...SUBTLE SHORTWAVE RIDING WILL
DOMINATE THE CENTRAL PLAINS ALOFT...WHILE AT THE
SURFACE...FAIRLY LIGHT BUT STEADY WESTERLY BREEZES WILL PREVAIL IN
THE WAKE OF THE LOW DEPARTING EAST TOWARD THE LOWER GREAT LAKES.
MADE VERY LITTLE CHANGE TO HIGHS...AS THIS SHOULD BE THE MILDEST
DAY OF THE WEEK IN MOST AREAS AND AM AIMING FOR UPPER 40S
NORTH/NEAR 50 TRI-CITIES AND MID-UPPER 50S KS ZONES.
TUES NIGHT...IT REMAIN PRECIP FREE ACROSS THE CWA...ALTHOUGH
CHANGES WILL GET UNDERWAY AS EAST-NORTHEAST SURFACE WINDS RAMP UP
TO 15+ MPH AS THE NIGHT GOES ON...IN RESPONSE TO CYCLOGENESIS
TAKING PLACE IN THE SOUTHEAST CO/OK PANHANDLE AREA. ALOFT...THERE
IS GOOD MODEL CONSENSUS AMONGST THE NAM/GFS/ECMWF THAT THE
POWERFUL SHORTWAVE AXIS WILL BE NEAR THE 4-CORNERS AT 12Z WED
MORNING. FOR LOW TEMPS...ALMOST NO CHANGE WITH UPPER 20S/LOW 30S.
LAST BUT CERTAINLY NOT LEAST...THE WEDNESDAY INTO WED NIGHT
PERIODS PROMISE TO BE QUITE ACTIVE...BUT AS STATED AT THE
TOP...THE DETAILS REGARDING SNOW ACCUMULATIONS ARE STILL A BIT
SKETCHY. IN SHORT...MODEL CONSENSUS ON THE TRACK OF THE UPPER WAVE
IS PRETTY DECENT...AS IT MIGRATES FROM THE 4-CORNERS REGION AT
SUNRISE WEDNESDAY...TO OVER THE HEART OF NEB/KS EARLY WED
EVENING...TO SOMEWHERE OVER IA/MO BY SUNRISE THURS MORNING. THE
NAM HAS BEEN A BIT OF AN OUTLIER VERSUS OTHER MODELS IN
INTENSIFYING/CLOSING OFF THE 500MB CIRCULATION DIRECTLY OVER THE
CWA AS THE WAVE PASSES...WHICH IN TURN RESULTS IN SOME FAIRLY
CONCERNING MODEL-GENERATED SNOW AMOUNTS IN EXCESS OF 6 INCHES
MAINLY NORTH OF I-80. HOWEVER...BOTH THE GFS/ECMWF MAINTAIN A BIT
MORE SOUTHERN TRACK OF THE SYSTEM...TAKING THE PRIMARY SURFACE LOW
GENERALLY ACROSS THE OK/KS BORDER INTO CENTRAL MO...VERSUS THE NAM
WHICH TAKES THE SURFACE LOW MORE OVER THE KC METRO AREA. THIS
TRACK WILL OBVIOUSLY PROVE CRITICAL AS TO WHETHER THE NORTHERN 1/2
OR SOUTHERN 1/2 OF THE CWA WILL REALIZE THE MOST SNOW...AND FOR
NOW HAVE GENERALLY USED A BLEND OF MODEL SOLUTIONS FOR THIS
MORNING/S FORECAST...WHICH RESULTS IN A VERY ROUGH STORM TOTAL
SNOW FORECAST OF 2-4 INCHES CWA-WIDE. CERTAINLY IT IS POSSIBLE
THAT SOME AREAS COULD SEE MORE THAN THIS...BUT UNTIL THE TRACK
BECOMES A BIT CLEARER IT WOULD NOT BE WISE TO TRY PINPOINTING
HIGHER THAN THIS. ALTHOUGH THIS IS A FAIRLY PROGRESSIVE
SYSTEM...IT WILL HAVE QUITE A BIT GOING FOR IT IN TERMS OF STRONG
UPPER JET DIVERGENCE AND ASSOCIATED MID LEVEL
FRONTOGENESIS/DEFORMATION. TIMING-WISE...THE GENERAL EXPECTATION
IS THAT SNOW WILL FIRST BREAK OUT MAINLY ACROSS THE NORTHWEST 1/3
OF THE CWA/NORTHWEST OF THE TRI-CITIES/DURING THE MORNING
HOURS...AND THEN RAPIDLY EXPAND ACROSS THE REMAINDER OF THE AREA
WED AFTERNOON INTO WED EVENING...WHILE AT THE SAME TIME SUSTAINED
SPEEDS WILL RAMP UP INTO THE 20-30 MPH RANGE WITH GUSTS TO AROUND
40 MPH...FIRST FROM THE NORTHEAST AND THEN SWINGING AROUND TO THE
NORTHWEST BY EVENING. VISIBILITY RESTRICTIONS WILL BE AN ISSUE FOR
SURE...BUT NOT THINKING BLIZZARD CRITERIA OF WIDESPREAD 1/4 MILE
OR LESS AT THIS POINT. LIKELY 60-70 POPS ARE IN PLACE FOR MUCH OF
THE CWA DURING THE AFTERNOON/EVENING HOURS...AND THESE WILL LIKELY
BE RAISED FURTHER OVER THE NEXT FEW DAYS. AFTER
MIDNIGHT...LINGERED SOME 20-30 POPS WITHIN THE EASTERN 1/2 OF THE
CWA...BUT THE VAST MAJORITY OF ACCUMULATIONS SHOULD BE DONE BY
THEN...AND CERTAINLY SHOULD BE OVER WITH WELL BEFORE SUNRISE.
WINDS SHOULD ALSO DIMINISH SOMEWHAT PRIOR TO SUNRISE...RESULTING
IN IMPROVING VISIBILITIES IN ANY BLOWING SNOW. TEMPS ON WED WILL
ESSENTIALLY RISE VERY LITTLE IF ANY FROM OVERNIGHT LOWS...AND KEPT
HIGHS IN THE LOW 30S EXCEPT IN THE FAR SOUTHEAST...WHERE UPPER 30S
COULD BE ATTAINABLE. ALTHOUGH NOT EXPECTING MUCH OF AN ISSUE WITH
SLEET/FREEZING RAIN WITH THIS SYSTEM...WILL HAVE TO WATCH FAR
SOUTHEAST AREAS AROUND BELOIT KS AS THINGS FIRST GET UNDERWAY...AS
TEMPS ALOFT COULD BE JUST WARM ENOUGH FOR A BRIEF WINTRY MIX
BEFORE AN OUTRIGHT CHANGEOVER TO SNOW. FOR NOW THOUGH...HAVE KEPT
ALL MENTION OF MIXED-PHASE OUT OF THE GRIDS.
.LONG TERM...STARTING 12Z THURSDAY. GUIDANCE FROM THE
EC...OPERATIONAL GFS AND GEFS-MEAN ALL SUGGEST MID AND UPPER
LEVEL RIDGING WILL PERSIST OVER THE CENTRAL CONUS THROUGHOUT THE
LONG TERM FORECAST PERIOD. THE OVERALL LACK IN KINEMATIC FORCING
SHOULD PRESENT DRY CONDITIONS AS A RESULT. GUIDANCE FROM THE EC
AND OPERATIONAL GFS SUGGEST THE DEPARTING STORM SYSTEM TO OUR EAST
WILL PROVIDE A STIFF NORTHWEST WIND TO OUR AREA THROUGH MUCH OF
THURSDAY. THE INCREASING POTENTIAL FOR FRESH SNOWPACK ACROSS THE
AREA...WORKING IN CONCERT WITH LOW LEVEL COLD AIR
ADVECTION...MEANS TEMPERATURES WILL PROBABLY HAVE DIFFICULTY
CLIMBING ALL THAT FAR ON THURSDAY. GIVEN THIS...WENT AHEAD AND
UNDERCUT ALLBLEND BY 2-3 DEGREES FOR MANY LOCATIONS ACROSS THE CWA
WHICH PRESENTS HIGHS IN THE LOW 30S FOR THE MOST PART. THERE IS A
CHANCE THURSDAY HIGH TEMPERATURES WILL NEED TO BE DECREASED MORE
IN THE COMING DAYS SHOULD THE ANTICIPATED SNOWFALL MATERIALIZE ON
WEDNESDAY. CLEAR SKIES AND A DECREASING LOW LEVEL WIND
FIELD...ALONG WITH A FEW INCHES OF SNOW ON THE GROUND...WILL
LIKELY PRESENT A COLD NIGHT THURSDAY NIGHT. ~30 DEGREE TEMPERATURE
DROP-OFFS DO NOT SEEM UNREASONABLE GIVEN THE EXPECTED SYNOPTIC
SETUP...WHICH WOULD PROVIDE OVERNIGHT LOWS GENERALLY IN THE LOW
TEENS. ALLBLEND ONLY PROVIDE LOWS IN THE MID TO UPPER TEENS AND AS
A RESULT...WENT AHEAD AND UNDERCUT ALLBLEND BY A COUPLE DEGREES
BUT MUCH LIKE THE HIGHS ON THURSDAY...THERE IS A POSSIBILITY THAT
THURSDAY NIGHT LOWS WILL NEED TO BE DECREASED A BIT MORE IN THE
COMING DAYS. A PERSISTENT WESTERLY COMPONENT TO THE LOW LEVEL WIND
FIELD...ALONG WITH MODEST LOW LEVEL WARM AIR ADVECTION...SHOULD
HELP THE SNOWPACK ERODE QUITE A BIT HEADING INTO FRIDAY...WITH A
RESULTANT WARMING TREND EXPECTED. NO REAL REASON TO DISAGREE WITH
ALLBLEND WHICH PRESENTED AFTERNOON HIGHS IN THE 30S AND 40S AND
FRIDAY NIGHT LOWS IN THE MID TO UPPER TEENS. THERE ARE INDICATIONS
FROM THE EC AND OPERATIONAL GFS OF A BACKDOOR COLD FRONT PUSHING
ACROSS THE AREA HEADING INTO THE DAY SATURDAY...WITH ALLBLEND
PRESENTING A SUBTLE COOLING TREND TO FINISH THE LONG TERM FORECAST
PERIOD. NO REASON TO DISAGREE WITH ALLBLEND SO LEFT SUNDAY HIGH
TEMPERATURE IN THE 30S FOR MOST LOCATIONS ACROSS THE CWA.
&&
.PREV DISCUSSION... /ISSUED 1015 PM CST SUN DEC 16 2012/
AVIATION...06Z KGRI TAF. LOW CLOUDS HAVE MOVED FURTHER EAST AND
MID CLOUDS HAVE MOVED IN FROM THE WEST. EXPECT IT WILL BE MORE
DIFFICULT NOW FOR THE LOW CLOUDS TO SPREAD BACK INTO KGRI GIVEN
RECENT MODEL RUNS THAT PUSH A SFC TROUGH THROUGH PRIOR TO DAWN
AND TURN THE SFC WINDS TO WESTERLY. THEREFORE...HAVE REMOVED TEMPO
GROUP THAT HAD INDICATED IFR CONDITIONS FOR THE HOURS AROUND DAWN.
BELIEVE THAT VFR CONDITIONS WILL PERSIST THROUGH THE TAF VALID
PERIOD.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
SHORT TERM...PFANNKUCH
LONG TERM...BRYANT
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1024 AM EST MON DEC 17 2012
.SYNOPSIS...
CLOUDY SKIES WILL PREVAIL ACROSS THE REGION TODAY WITH RAIN
RETURNING LATE THIS AFTERNOON TO SOUTHWESTERN NEW YORK STATE. A LOW
WILL TRACK ACROSS PENNSYLVANIA AND INTO SOUTHERN NEW ENGLAND WHICH
WILL BRING A STEADY RAIN INTO THE REMAINDER OF THE REGION THIS
EVENING WITH RAIN LINGERING INTO TUESDAY. WARM TEMPERATURES WILL
CONTINUE THROUGH MUCH OF THE WEEK BEFORE A TURN TOWARDS COLDER AND
MORE WINTRY WEATHER BY FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
REGIONAL RADARS THIS LATE MORNING DISPLAY THE AREA OF RAIN/WINTRY
MIX NOW EXITING OUR CWA TO THE NORTH AND EAST. A LITTLE DRIZZLE MAY
LINGER ACROSS THE NORTH COUNTRY FOR ANOTHER HOUR...OTHERWISE WE WILL
HAVE A BRIEF DRY PERIOD BEFORE THE NEXT SYSTEM ARRIVES FROM THE OHIO
VALLEY.
SATELLITE IMAGERY THIS MORNING DISPLAYS PLENTY OF CLOUDS ACROSS THE
GREAT LAKES AND NORTHEAST REGION. BUFKIT SOUNDINGS OF THE NAM AND
GFS DISPLAY ABUNDANT MOISTURE IN THE LOWEST 5K FEET AND EXPECT
CLOUDY SKIES TO REMAIN THROUGH THE BULK OF THE DAY.
ANOTHER DAY OF MUCH ABOVE NORMAL TEMPERATURES TO MOST
LOCATIONS...WITH HIGHS NEAR OR ABOVE 50 ACROSS THE WESTERN TWO
THIRDS OF THE CWA. A DEVELOPING SOUTHWESTERLY FLOW MAY KEEP BUFFALO
FROM RISING MUCH ABOVE 50...BUT DOWNSLOPING WILL CONTINUE IN THE
GENESEE VALLEY AND FINGER LAKES REGIONS...WHERE TEMPERATURES SHOULD
REACH THE LOWER TO MID 50S.
AN UPPER LEVEL TROF AND ASSOCIATED SURFACE LOW WILL TRACK FROM THE
OHIO VALLEY AND INTO THE REGION TONIGHT. NAM BUFKIT INDICATES LIFT
WELL ALOFT ASSOCIATED WITH THE UPPER TROF...AS WELL AS WARM AIR
ADVECTION IN THE MID-LEVELS. GFS/RGEM/NAM AND SREF ENSEMBLES ARE IN
EXCELLENT AGREEMENT IN TERMS OF QPF...AND GIVEN THE LARGE-SCALE
NATURE OF THE PRECIPITATION HAVE A HIGH CONFIDENCE IN MEASURABLE
PRECIPITATION TONIGHT. NOTED THE 09Z HRRR AND THE 06Z RUN OF THE
NAM ARE A BIT SLOWER THAN PREVIOUS GUIDANCE...SO TRY TO BLEND THIS
SLOWER TIMING WITH FASTER MODELS SUCH AS THE GFS. USING THIS
APPROACH...EXPECT RAIN WILL SPREAD FROM SOUTH TO NORTH THIS
EVENING...LIKELY ENTERING WESTERN PORTIONS OF THE SOUTHERN TIER
AROUND OR JUST AFTER.
THIS SHOULD BE A FAIRLY SOAKING RAINFALL...BRINGING AN AVERAGE OF A
HALF INCH OF RAIN TO THE REGION TONIGHT. LOCALLY HIGHER AMOUNTS TO
AN INCH ARE POSSIBLE...WITH THE BEST CHANCE OF THIS IN LOCATIONS
EAST OF ROCHESTER. FORTUNATELY...WARMER AIR SHOULD BE IN PLACE BY
TONIGHT...WITH ALL PRECIPITATION LIKELY FALLING AS RAIN. EXPECT
FOG WILL DEVELOP IN SOME AREAS TONIGHT
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
WIDESPREAD STEADY RAIN WILL BE ACROSS THE AREA TUESDAY MORNING IN
AREA OF STRONG ISENTROPIC ASCENT AHEAD OF THE APPROACHING SURFACE
LOW. LATEST MODELS CONTINUING TO SUGGEST THAT THE LOW WILL REFORM
ALONG THE SOUTHERN NEW ENGLAND COAST DURING THE DAY TUESDAY AND MOVE
UP THE NEW ENGLAND COAST. AS THIS HAPPENS...COLDER AIR WILL BE DRAWN
INTO THE STATE TUESDAY AFTERNOON AND TUESDAY NIGHT. THIS SHOULD
RESULT IN A GRADUAL TRANSITION TO SOME SCATTERED LAKE/OROGRAPHICALLY
ENHANCED RAIN/SNOW SHOWERS WITH ALL SNOW BECOMING LIKELY OVER THE
HIGHER TERRAIN. ANY SNOW ACCUMULATIONS SHOULD BE LIMITED TO LESS
THAN 2 INCHES AND LIKELY CONFINED TO THE HIGHER TERRAIN TUESDAY
NIGHT.
BUILDING HEIGHTS EXPECTED ON WEDNESDAY IN RESPONSE TO STRONG
SHORTWAVE MOVING ACROSS THE FOUR CORNERS REGION. WEAK SURFACE RIDGE
BUILDING ACROSS THE REGION SHOULD BRING MAINLY QUIET WEATHER
WEDNESDAY AND WEDNESDAY NIGHT...ALTHOUGH THERE MAY BE SOME LINGERING
LIGHT PRECIPITATION ACROSS THE NORTH COUNTRY WEDNESDAY. PERHAPS THE
POTENTIAL FOR A TOUCH OF SUN WEDNESDAY MAY HELP TO GET TEMPERATURES
INTO THE UPPER 30S TO LOWER 40S.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A SIGNIFICANT STORM MAY BRING MUCH MORE IMPACTFUL WEATHER LATE NEXT
WEEK INTO THE WEEKEND BROUGHT ON BY A DIGGING UPPER LEVEL TROUGH
WHICH LOOKS TO TAKE ON A NEGATIVE TILT OVER THE GREAT LAKES. THERE
ARE STILL SOME DIFFERENCES MAINLY IN TIMING OF THE SURFACE LOW WITH
THE 12Z GFS ABOUT SIX HOURS FASTER THAN THE 12Z ECMWF BUT THERE IS
NOW SOME AGREEMENT IN THE TRACK SHIFTING SOMEWHERE OVER THE EASTERN
LAKES THURSDAY THROUGH FRIDAY. THE 12Z GFS SHOWS THE LOW CENTER
TRACKING JUST TO THE NORTHWEST OF THE LAKES WHILE THE 12Z ECMWF
SHOWS THE STORM TRACK ACROSS OUR FORECAST AREA ALONG THE I-90
CORRIDOR. THE GFS TRACK IS A CLIMATOLOGICALLY FAVORED TRACK FOR HIGH
WINDS WITH 12Z BUFKIT PROFILES SHOWING WIND GUSTS TO 50 OR 60 MPH
POSSIBLE ON FRIDAY ONCE THE SYSTEM SHIFTS TO OUR EAST AND COLD
ADVECTION HELPS MIX 60 TO 70 KT WINDS AT 850MB TO THE SURFACE. THE
ECMWF TRACK WOULD NOT BRING WINDS AS STRONG WITH THE CENTER SHIFTING
OVERHEAD.
AHEAD OF THIS POTENTIAL WIND IMPACT SOUTHERLY FLOW EAST OF THE
STORM SYSTEM WILL BRING WARM AIR AND INCREASING MOISTURE. FORECAST
HIGHS ON THURSDAY LOOK TO BE ABOVE NORMAL AVERAGING IN THE MID 40S
ACROSS INLAND AREAS AND UPPER 40S TO NEAR 50 ALONG THE LAKE SHORES
WITH A DOWNSLOPING SOUTHERLY WIND. WITH SUCH MILD TEMPERATURES ANY
CHANCE FOR PRECIPITATION WOULD COME IN THE FORM OF RAIN DURING THE
DAY. THURSDAY NIGHT WE SHOULD SEE A CHANGE TO A PERIOD OF COOLER
WEATHER AS THE UPPER LEVEL TROUGH SHIFTS OVER THE LOWER LAKES AND
THE SURFACE LOW CROSSES NEAR NEW YORK.
THE COOL DOWN CONTINUES FRIDAY INTO SATURDAY WITH BOTH MODELS
SHIFTING THE LOW EAST OR NORTH EAST OF THE FORECAST AREA. LIKELY
PROBABILITIES FOR WIDESPREAD SYNOPTIC SNOW AND GUSTY WINDS ARE ARE
INCLUDED IN THE FORECAST FOR FRIDAY WITH SURFACE TEMPERATURES ONLY
IN THE 30S. BOTH MODELS CONTINUE TO SHOW COLD AIR IN PLACE THROUGH
THE WEEKEND WITH WEST TO NORTHWEST WINDS OVER THE LAKES WHICH
FAVORS A SET UP FOR ACCUMULATING LAKE EFFECT SNOW DOWN WIND OF
THE LAKES OVER THE WEEKEND.
&&
.AVIATION /16Z MONDAY THROUGH FRIDAY/...
AN AREA OF RAIN WILL LIFT NORTHEAST AND OUT OF THE REGION THROUGH
MID-MORNING...WITH OTHERWISE DRY CONDITIONS ACROSS THE REGION.
CIGS WILL BE THE MAIN CONCERN FOR TODAY. FOR THE MOST
PART...EXPECT EITHER VFR OR MVFR CONDITIONS TODAY. THE EXCEPTION TO
THIS IS JHW...WHERE FOG AND CIGS BLO 1000 FEET SHOULD LINGER
THROUGH MUCH OF THIS MORNING BEFORE FINALLY LIFTING. CONFIDENCE IS
MODERATE TO LOW IN TIMING OF THIS.
RAIN WILL SPREAD INTO THE REGION THIS EVENING...WITH CONDITIONS
EXPECTED TO LOWER TO IFR AS THE FLOW BECOMES MORE NE AND THEN NW.
OUTLOOK...
TUESDAY...WIDESPREAD IFR WITH RAIN.
WEDNESDAY...MAINLY VFR.
THURSDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
THURSDAY NIGHT...MVFR WITH A CHANCE OF SHOWERS. GUSTY WINDS.
FRIDAY...MVFR/IFR WITH A CHANCE OF SNOW. GUSTY WINDS.
&&
.MARINE...
HAVE DROPPED THE SCA FOR THE EASTERN HALF OF LAKE ONTARIO AS WINDS
AND WAVES CONTINUE TO DIMINISH. WAVES WILL STILL NEAR 4 FEET THIS
MORNING ACROSS FAR NORTHEASTERN PORTIONS OF THE LAKE...BUT A
WEAKENING PRESSURE GRADIENT WILL ALLOW THESE WINDS AND WAVES TO
FURTHER DIMINISH THIS AFTERNOON.
WINDS WILL INCREASE AGAIN OUT OF THE NORTHWEST LATER TUESDAY BEHIND
ANOTHER AREA OF LOW PRESSURE. THIS MAY BRING SMALL CRAFT ADVISORY
CONDITIONS ONCE AGAIN...ESPECIALLY ON LAKE ONTARIO. THESE WINDS WILL
CONTINUE TUESDAY NIGHT BEFORE DIMINISHING ON WEDNESDAY.
A STRONGER STORM SYSTEM IS FORECAST TO MOVE INTO THE VICINITY OF THE
LOWER LAKES BY THURSDAY NIGHT AND FRIDAY. THIS MAY BRING A PERIOD OF
STRONGER WINDS...ALTHOUGH THE DETAILS REMAIN VERY UNCERTAIN.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...APFFEL/THOMAS
NEAR TERM...APFFEL/THOMAS
SHORT TERM...TMA
LONG TERM...SMITH
AVIATION...APFFEL
MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS BUFFALO NY
725 AM EST MON DEC 17 2012
.SYNOPSIS...
WEAKENING LOW PRESSURE WILL LIFT INTO CANADA TODAY...WITH LINGERING
SHOWERS TAPERING OFF. ANOTHER LOW WILL TRACK ACROSS PENNSYLVANIA AND
INTO SOUTHERN NEW ENGLAND WHICH WILL BRING A STEADY RAIN TO THE
REGION THIS EVENING AND INTO TUESDAY. WARM TEMPERATURES WILL
CONTINUE THROUGH MUCH OF THE WEEK BEFORE A TURN TOWARDS COLDER AND
MORE WINTRY WEATHER BY FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AT 700 AM...RADAR SHOWS A FAIRLY LARGE AREA OF STEADY RAIN ACROSS
LEWIS AND JEFFERSON COUNTIES. THIS WILL LIFT NORTHEAST OF THE CWA
THROUGH MID-MORNING. NEARBY MESONET SITES REPORT TEMPERATURES
CLOSE TO FREEZING...SO PATCHY AREAS OF FREEZING RAIN STILL CAN/T
BE RULED OUT EVEN THOUGH THE MAJORITY OF PRECIPITATION IS FALLING
AS RAIN. ANY THREATS OF ICING WILL END BY MID-MORNING AS THE RAIN
ENDS AND TEMPERATURES RISE ABOVE FREEZING.
ONCE THIS SHORTWAVE AND WEAK FRONTAL BOUNDARY EXIT THIS
MORNING...EXPECT A DRY PERIOD ACROSS MUCH OF WESTERN NEW YORK FOR
MUCH OF THE DAYLIGHT HOURS. BUFKIT SOUNDINGS SUGGEST THERE IS A
LIMITED OPPORTUNITY FOR SOME BREAKS OF SUNSHINE THIS MORNING AND
EARLY AFTERNOON...AS MOISTURE THINS OUT. THIS WILL BRING ANOTHER
DAY OF MUCH ABOVE NORMAL TEMPERATURES TO MOST LOCATIONS...WITH
HIGHS NEAR OR ABOVE 50 ACROSS THE WESTERN TWO THIRDS OF THE CWA. A
DEVELOPING SOUTHWESTERLY FLOW MAY KEEP BUFFALO FROM RISING MUCH
ABOVE 50...BUT DOWNSLOPING WILL CONTINUE IN THE GENESEE VALLEY AND
FINGER LAKES REGIONS...WHERE TEMPERATURES SHOULD REACH THE LOWER
TO MID 50S.
AN UPPER LEVEL TROF AND ASSOCIATED SURFACE LOW WILL TRACK FROM THE
OHIO VALLEY AND INTO THE REGION TONIGHT. NAM BUFKIT INDICATES LIFT
WELL ALOFT ASSOCIATED WITH THE UPPER TROF...AS WELL AS WARM AIR
ADVECTION IN THE MID-LEVELS. GFS/RGEM/NAM AND SREF ENSEMBLES ARE IN
EXCELLENT AGREEMENT IN TERMS OF QPF...AND GIVEN THE LARGE-SCALE
NATURE OF THE PRECIPITATION HAVE A HIGH CONFIDENCE IN MEASURABLE
PRECIPITATION TONIGHT. NOTED THE 09Z HRRR AND THE 06Z RUN OF THE
NAM ARE A BIT SLOWER THAN PREVIOUS GUIDANCE...SO TRY TO BLEND THIS
SLOWER TIMING WITH FASTER MODELS SUCH AS THE GFS. USING THIS
APPROACH...EXPECT RAIN WILL SPREAD FROM SOUTH TO NORTH THIS
EVENING...LIKELY ENTERING WESTERN PORTIONS OF THE SOUTHERN TIER
AROUND OR JUST AFTER.
THIS SHOULD BE A FAIRLY SOAKING RAINFALL...BRINGING AN AVERAGE OF A
HALF INCH OF RAIN TO THE REGION TONIGHT. LOCALLY HIGHER AMOUNTS TO
AN INCH ARE POSSIBLE...WITH THE BEST CHANCE OF THIS IN LOCATIONS
EAST OF ROCHESTER. FORTUNATELY...WARMER AIR SHOULD BE IN PLACE BY
TONIGHT...WITH ALL PRECIPITATION LIKELY FALLING AS RAIN. EXPECT
FOG WILL DEVELOP IN SOME AREAS TONIGHT
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
WIDESPREAD STEADY RAIN WILL BE ACROSS THE AREA TUESDAY MORNING IN
AREA OF STRONG ISENTROPIC ASCENT AHEAD OF THE APPROACHING SURFACE
LOW. LATEST MODELS CONTINUING TO SUGGEST THAT THE LOW WILL REFORM
ALONG THE SOUTHERN NEW ENGLAND COAST DURING THE DAY TUESDAY AND MOVE
UP THE NEW ENGLAND COAST. AS THIS HAPPENS...COLDER AIR WILL BE DRAWN
INTO THE STATE TUESDAY AFTERNOON AND TUESDAY NIGHT. THIS SHOULD
RESULT IN A GRADUAL TRANSITION TO SOME SCATTERED LAKE/OROGRAPHICALLY
ENHANCED RAIN/SNOW SHOWERS WITH ALL SNOW BECOMING LIKELY OVER THE
HIGHER TERRAIN. ANY SNOW ACCUMULATIONS SHOULD BE LIMITED TO LESS
THAN 2 INCHES AND LIKELY CONFINED TO THE HIGHER TERRAIN TUESDAY
NIGHT.
BUILDING HEIGHTS EXPECTED ON WEDNESDAY IN RESPONSE TO STRONG
SHORTWAVE MOVING ACROSS THE FOUR CORNERS REGION. WEAK SURFACE RIDGE
BUILDING ACROSS THE REGION SHOULD BRING MAINLY QUIET WEATHER
WEDNESDAY AND WEDNESDAY NIGHT...ALTHOUGH THERE MAY BE SOME LINGERING
LIGHT PRECIPITATION ACROSS THE NORTH COUNTRY WEDNESDAY. PERHAPS THE
POTENTIAL FOR A TOUCH OF SUN WEDNESDAY MAY HELP TO GET TEMPERATURES
INTO THE UPPER 30S TO LOWER 40S.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A SIGNIFICANT STORM MAY BRING MUCH MORE IMPACTFUL WEATHER LATE NEXT
WEEK INTO THE WEEKEND BROUGHT ON BY A DIGGING UPPER LEVEL TROUGH
WHICH LOOKS TO TAKE ON A NEGATIVE TILT OVER THE GREAT LAKES. THERE
ARE STILL SOME DIFFERENCES MAINLY IN TIMING OF THE SURFACE LOW WITH
THE 12Z GFS ABOUT SIX HOURS FASTER THAN THE 12Z ECMWF BUT THERE IS
NOW SOME AGREEMENT IN THE TRACK SHIFTING SOMEWHERE OVER THE EASTERN
LAKES THURSDAY THROUGH FRIDAY. THE 12Z GFS SHOWS THE LOW CENTER
TRACKING JUST TO THE NORTHWEST OF THE LAKES WHILE THE 12Z ECMWF
SHOWS THE STORM TRACK ACROSS OUR FORECAST AREA ALONG THE I-90
CORRIDOR. THE GFS TRACK IS A CLIMATOLOGICALLY FAVORED TRACK FOR HIGH
WINDS WITH 12Z BUFKIT PROFILES SHOWING WIND GUSTS TO 50 OR 60 MPH
POSSIBLE ON FRIDAY ONCE THE SYSTEM SHIFTS TO OUR EAST AND COLD
ADVECTION HELPS MIX 60 TO 70 KT WINDS AT 850MB TO THE SURFACE. THE
ECMWF TRACK WOULD NOT BRING WINDS AS STRONG WITH THE CENTER SHIFTING
OVERHEAD.
AHEAD OF THIS POTENTIAL WIND IMPACT SOUTHERLY FLOW EAST OF THE
STORM SYSTEM WILL BRING WARM AIR AND INCREASING MOISTURE. FORECAST
HIGHS ON THURSDAY LOOK TO BE ABOVE NORMAL AVERAGING IN THE MID 40S
ACROSS INLAND AREAS AND UPPER 40S TO NEAR 50 ALONG THE LAKE SHORES
WITH A DOWNSLOPING SOUTHERLY WIND. WITH SUCH MILD TEMPERATURES ANY
CHANCE FOR PRECIPITATION WOULD COME IN THE FORM OF RAIN DURING THE
DAY. THURSDAY NIGHT WE SHOULD SEE A CHANGE TO A PERIOD OF COOLER
WEATHER AS THE UPPER LEVEL TROUGH SHIFTS OVER THE LOWER LAKES AND
THE SURFACE LOW CROSSES NEAR NEW YORK.
THE COOL DOWN CONTINUES FRIDAY INTO SATURDAY WITH BOTH MODELS
SHIFTING THE LOW EAST OR NORTH EAST OF THE FORECAST AREA. LIKELY
PROBABILITIES FOR WIDESPREAD SYNOPTIC SNOW AND GUSTY WINDS ARE ARE
INCLUDED IN THE FORECAST FOR FRIDAY WITH SURFACE TEMPERATURES ONLY
IN THE 30S. BOTH MODELS CONTINUE TO SHOW COLD AIR IN PLACE THROUGH
THE WEEKEND WITH WEST TO NORTHWEST WINDS OVER THE LAKES WHICH
FAVORS A SET UP FOR ACCUMULATING LAKE EFFECT SNOW DOWN WIND OF
THE LAKES OVER THE WEEKEND.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AN AREA OF RAIN WILL LIFT NORTHEAST AND OUT OF THE REGION THROUGH
MID-MORNING...WITH OTHERWISE DRY CONDITIONS ACROSS THE REGION.
CIGS WILL BE THE MAIN CONCERN FOR TODAY. FOR THE MOST
PART...EXPECT EITHER VFR OR MVFR CONDITIONS TODAY. THE EXCEPTION TO
THIS IS JHW...WHERE FOG AND CIGS BLO 1000 FEET SHOULD LINGER
THROUGH MUCH OF THIS MORNING BEFORE FINALLY LIFTING. CONFIDENCE IS
MODERATE TO LOW IN TIMING OF THIS.
RAIN WILL SPREAD INTO THE REGION THIS EVENING...WITH CONDITIONS
EXPECTED TO LOWER TO IFR AS THE FLOW BECOMES MORE NE AND THEN NW.
OUTLOOK...
TUESDAY...WIDESPREAD IFR WITH RAIN.
WEDNESDAY...MAINLY VFR.
THURSDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
THURSDAY NIGHT...MVFR WITH A CHANCE OF SHOWERS. GUSTY WINDS.
FRIDAY...MVFR/IFR WITH A CHANCE OF SNOW. GUSTY WINDS.
&&
.MARINE...
MODERATE SOUTHERLY WINDS WILL TAPER OFF THROUGH THIS MORNING. THIS
WILL MAINTAIN SMALL CRAFT ADVISORY CONDITIONS AT THE NORTHEAST END
OF LAKE ONTARIO THROUGH THIS MORNING. THE PRESSURE GRADIENT WILL
RELAX ACROSS THE AREA THIS AFTERNOON...ALLOWING WINDS TO DIMINISH.
WINDS WILL INCREASE AGAIN OUT OF THE NORTHWEST LATER TUESDAY BEHIND
ANOTHER AREA OF LOW PRESSURE. THIS MAY BRING SMALL CRAFT ADVISORY
CONDITIONS ONCE AGAIN...ESPECIALLY ON LAKE ONTARIO. THESE WINDS WILL
CONTINUE TUESDAY NIGHT BEFORE DIMINISHING ON WEDNESDAY.
A STRONGER STORM SYSTEM IS FORECAST TO MOVE INTO THE VICINITY OF THE
LOWER LAKES BY THURSDAY NIGHT AND FRIDAY. THIS MAY BRING A PERIOD OF
STRONGER WINDS...ALTHOUGH THE DETAILS REMAIN VERY UNCERTAIN.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR LOZ044-
045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...TMA
LONG TERM...SMITH
AVIATION...APFFEL
MARINE...APFFEL/TMA
AREA FORECAST DISCUSSION
NWS BUFFALO NY
640 AM EST MON DEC 17 2012
.SYNOPSIS...
WEAKENING LOW PRESSURE WILL LIFT INTO CANADA TODAY...WITH LINGERING
SHOWERS TAPERING OFF. ANOTHER LOW WILL TRACK ACROSS PENNSYLVANIA AND
INTO SOUTHERN NEW ENGLAND WHICH WILL BRING A STEADY RAIN TO THE
REGION THIS EVENING AND INTO TUESDAY. WARM TEMPERATURES WILL
CONTINUE THROUGH MUCH OF THE WEEK BEFORE A TURN TOWARDS COLDER AND
MORE WINTRY WEATHER BY FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AT 600 AM...RADAR SHOWS A FAIRLY LARGE AREA OF STEADY RAIN EAST OF
LAKE ONTARIO. MODEL GUIDANCE HAS NOT HAD A VERY GOOD HANDLE ON
THIS...WITH SEVERAL OF THE 00Z MODELS STRUGGLING TO HANDLE A
SHORTWAVE WHICH IS MOVING ACROSS A WEAK SURFACE BOUNDARY AND
ASSOCIATED TROF. THE 00Z RGEM AND THE 04Z HRRR DO CAPTURE THIS
FAIRLY WELL...AND PROVIDE FAIRLY GOOD GUIDANCE THROUGH THE EARLY
MORNING HOURS. FOLLOWING THIS...EXPECT THIS AREA TO LIFT OUT OF
THE CWA AROUND MID-MORNING.
THERE CONTINUES TO BE ONE LINGERING AREA OF CONCERN ACROSS LEWIS
COUNTY EARLY THIS MORNING. AIR TO THE NORTH AND EAST OF OUR CWA IS
CONSIDERABLY COOLER. THE VAST MAJORITY OF OBSERVATIONS FROM AND
AROUND LEWIS COUNTY ARE REPORTING TEMPERATURES IN THE MID TO UPPER
30S...BUT THERE STILL MAY BE A FEW SPOTS NEAR FREEZING. SOUNDINGS
SUGGEST ANY AREAS BELOW FREEZING WOULD GET FREEZING RAIN. BECAUSE
OF THE ISOLATED NATURE OF SUB- FREEZING TEMPERATURES...WILL NOT
ISSUE AN ADVISORY...BUT WILL HIGHLIGHT THE POTENTIAL IN AN SPS
PRODUCT. TEMPERATURES WILL SLOWLY RISE EAST OF LAKE ONTARIO
TODAY...WITH HIGHS FROM AROUND 40 TO THE UPPER 40S...WITH THE
COOLEST TEMPERATURES REMAINING ACROSS LEWIS COUNTY.
ONCE THIS SHORTWAVE AND WEAK FRONTAL BOUNDARY EXIT TO THE NORTHEAST
THIS MORNING...EXPECT A DRY PERIOD ACROSS MUCH OF WESTERN NEW YORK
FOR MUCH OF THE DAYLIGHT HOURS. OUTSIDE OF LINGERING LOW LEVEL
MOISTURE IN THE SOUTHERN TIER...BUFKIT SOUNDINGS SUGGEST EVEN AN
OPPORTUNITY FOR SOME BREAKS OF SUNSHINE LATE THIS MORNING AND EARLY
AFTERNOON...AS MOISTURE THINS OUT. THIS WILL BRING ANOTHER DAY OF
MUCH ABOVE NORMAL TEMPERATURES TO MOST LOCATIONS...WITH HIGHS NEAR
OR ABOVE 50 ACROSS THE WESTERN TWO THIRDS OF THE CWA. A DEVELOPING
SOUTHWESTERLY FLOW MAY KEEP BUFFALO FROM RISING MUCH ABOVE 50...BUT
DOWNSLOPING WILL CONTINUE IN THE GENESEE VALLEY AND FINGER LAKES
REGIONS...WHERE TEMPERATURES SHOULD REACH THE LOWER TO MID 50S.
AN UPPER LEVEL TROF AND ASSOCIATED SURFACE LOW WILL TRACK FROM THE
OHIO VALLEY AND INTO THE REGION TONIGHT. NAM BUFKIT INDICATES LIFT
WELL ALOFT ASSOCIATED WITH THE UPPER TROF...AS WELL AS WARM AIR
ADVECTION IN THE MID-LEVELS. GFS/RGEM/NAM AND SREF ENSEMBLES ARE IN
EXCELLENT AGREEMENT IN TERMS OF QPF...AND GIVEN THE LARGE-SCALE
NATURE OF THE PRECIPITATION HAVE A HIGH CONFIDENCE IN MEASURABLE
PRECIPITATION TONIGHT. RAIN WILL SPREAD FROM SOUTH TO NORTH THIS
EVENING...LIKELY ENTERING WESTERN PORTIONS OF THE SOUTHERN TIER JUST
AROUND SUNSET.
THIS SHOULD BE A FAIRLY SOAKING RAINFALL...BRINGING AN AVERAGE OF A
HALF INCH OF RAIN TO THE REGION TONIGHT. LOCALLY HIGHER AMOUNTS TO
AN INCH ARE POSSIBLE...WITH THE BEST CHANCE OF THIS IN LOCATIONS
EAST OF ROCHESTER. FORTUNATELY...WARMER AIR SHOULD BE IN PLACE BY
TONIGHT...WITH ALL PRECIPITATION LIKELY FALLING AS RAIN.
EXPECT SOME PATCHY FOG EARLY THIS MORNING IN THE VALLEYS OF THE
SOUTHERN TIER...WITH A BIT MORE WIDESPREAD FOG POSSIBLE TONIGHT.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
WIDESPREAD STEADY RAIN WILL BE ACROSS THE AREA TUESDAY MORNING IN
AREA OF STRONG ISENTROPIC ASCENT AHEAD OF THE APPROACHING SURFACE
LOW. LATEST MODELS CONTINUING TO SUGGEST THAT THE LOW WILL REFORM
ALONG THE SOUTHERN NEW ENGLAND COAST DURING THE DAY TUESDAY AND MOVE
UP THE NEW ENGLAND COAST. AS THIS HAPPENS...COLDER AIR WILL BE DRAWN
INTO THE STATE TUESDAY AFTERNOON AND TUESDAY NIGHT. THIS SHOULD
RESULT IN A GRADUAL TRANSITION TO SOME SCATTERED LAKE/OROGRAPHICALLY
ENHANCED RAIN/SNOW SHOWERS WITH ALL SNOW BECOMING LIKELY OVER THE
HIGHER TERRAIN. ANY SNOW ACCUMULATIONS SHOULD BE LIMITED TO LESS
THAN 2 INCHES AND LIKELY CONFINED TO THE HIGHER TERRAIN TUESDAY
NIGHT.
BUILDING HEIGHTS EXPECTED ON WEDNESDAY IN RESPONSE TO STRONG
SHORTWAVE MOVING ACROSS THE FOUR CORNERS REGION. WEAK SURFACE RIDGE
BUILDING ACROSS THE REGION SHOULD BRING MAINLY QUIET WEATHER
WEDNESDAY AND WEDNESDAY NIGHT...ALTHOUGH THERE MAY BE SOME LINGERING
LIGHT PRECIPITATION ACROSS THE NORTH COUNTRY WEDNESDAY. PERHAPS THE
POTENTIAL FOR A TOUCH OF SUN WEDNESDAY MAY HELP TO GET TEMPERATURES
INTO THE UPPER 30S TO LOWER 40S.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
A SIGNIFICANT STORM MAY BRING MUCH MORE IMPACTFUL WEATHER LATE NEXT
WEEK INTO THE WEEKEND BROUGHT ON BY A DIGGING UPPER LEVEL TROUGH
WHICH LOOKS TO TAKE ON A NEGATIVE TILT OVER THE GREAT LAKES. THERE
ARE STILL SOME DIFFERENCES MAINLY IN TIMING OF THE SURFACE LOW WITH
THE 12Z GFS ABOUT SIX HOURS FASTER THAN THE 12Z ECMWF BUT THERE IS
NOW SOME AGREEMENT IN THE TRACK SHIFTING SOMEWHERE OVER THE EASTERN
LAKES THURSDAY THROUGH FRIDAY. THE 12Z GFS SHOWS THE LOW CENTER
TRACKING JUST TO THE NORTHWEST OF THE LAKES WHILE THE 12Z ECMWF
SHOWS THE STORM TRACK ACROSS OUR FORECAST AREA ALONG THE I-90
CORRIDOR. THE GFS TRACK IS A CLIMATOLOGICALLY FAVORED TRACK FOR HIGH
WINDS WITH 12Z BUFKIT PROFILES SHOWING WIND GUSTS TO 50 OR 60 MPH
POSSIBLE ON FRIDAY ONCE THE SYSTEM SHIFTS TO OUR EAST AND COLD
ADVECTION HELPS MIX 60 TO 70 KT WINDS AT 850MB TO THE SURFACE. THE
ECMWF TRACK WOULD NOT BRING WINDS AS STRONG WITH THE CENTER SHIFTING
OVERHEAD.
AHEAD OF THIS POTENTIAL WIND IMPACT SOUTHERLY FLOW EAST OF THE
STORM SYSTEM WILL BRING WARM AIR AND INCREASING MOISTURE. FORECAST
HIGHS ON THURSDAY LOOK TO BE ABOVE NORMAL AVERAGING IN THE MID 40S
ACROSS INLAND AREAS AND UPPER 40S TO NEAR 50 ALONG THE LAKE SHORES
WITH A DOWNSLOPING SOUTHERLY WIND. WITH SUCH MILD TEMPERATURES ANY
CHANCE FOR PRECIPITATION WOULD COME IN THE FORM OF RAIN DURING THE
DAY. THURSDAY NIGHT WE SHOULD SEE A CHANGE TO A PERIOD OF COOLER
WEATHER AS THE UPPER LEVEL TROUGH SHIFTS OVER THE LOWER LAKES AND
THE SURFACE LOW CROSSES NEAR NEW YORK.
THE COOL DOWN CONTINUES FRIDAY INTO SATURDAY WITH BOTH MODELS
SHIFTING THE LOW EAST OR NORTH EAST OF THE FORECAST AREA. LIKELY
PROBABILITIES FOR WIDESPREAD SYNOPTIC SNOW AND GUSTY WINDS ARE ARE
INCLUDED IN THE FORECAST FOR FRIDAY WITH SURFACE TEMPERATURES ONLY
IN THE 30S. BOTH MODELS CONTINUE TO SHOW COLD AIR IN PLACE THROUGH
THE WEEKEND WITH WEST TO NORTHWEST WINDS OVER THE LAKES WHICH
FAVORS A SET UP FOR ACCUMULATING LAKE EFFECT SNOW DOWN WIND OF
THE LAKES OVER THE WEEKEND.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AN AREA OF RAIN WILL LIFT NORTHEAST AND OUT OF THE REGION THROUGH
MID-MORNING...WITH OTHERWISE DRY CONDITIONS ACROSS THE REGION.
CIGS WILL BE THE MAIN CONCERN FOR TODAY. FOR THE MOST
PART...EXPECT EITHER VFR OR MVFR CONDITIONS TODAY. THE EXCEPTION TO
THIS IS JHW...WHERE FOG AND CIGS BLO 1000 FEET SHOULD LINGER
THROUGH MUCH OF THIS MORNING BEFORE FINALLY LIFTING. CONFIDENCE IS
MODERATE TO LOW IN TIMING OF THIS.
RAIN WILL SPREAD INTO THE REGION THIS EVENING...WITH CONDITIONS
EXPECTED TO LOWER TO IFR AS THE FLOW BECOMES MORE NE AND THEN NW.
OUTLOOK...
TUESDAY...WIDESPREAD IFR WITH RAIN.
WEDNESDAY...MAINLY VFR.
THURSDAY...VFR/MVFR WITH A CHANCE OF SHOWERS.
THURSDAY NIGHT...MVFR WITH A CHANCE OF SHOWERS. GUSTY WINDS.
FRIDAY...MVFR/IFR WITH A CHANCE OF SNOW. GUSTY WINDS.
&&
.MARINE...
MODERATE SOUTHERLY WINDS WILL TAPER OFF THROUGH THIS MORNING. THIS
WILL MAINTAIN SMALL CRAFT ADVISORY CONDITIONS AT THE NORTHEAST END
OF LAKE ONTARIO THROUGH THIS MORNING. THE PRESSURE GRADIENT WILL
RELAX ACROSS THE AREA THIS AFTERNOON...ALLOWING WINDS TO DIMINISH.
WINDS WILL INCREASE AGAIN OUT OF THE NORTHWEST LATER TUESDAY BEHIND
ANOTHER AREA OF LOW PRESSURE. THIS MAY BRING SMALL CRAFT ADVISORY
CONDITIONS ONCE AGAIN...ESPECIALLY ON LAKE ONTARIO. THESE WINDS WILL
CONTINUE TUESDAY NIGHT BEFORE DIMINISHING ON WEDNESDAY.
A STRONGER STORM SYSTEM IS FORECAST TO MOVE INTO THE VICINITY OF THE
LOWER LAKES BY THURSDAY NIGHT AND FRIDAY. THIS MAY BRING A PERIOD OF
STRONGER WINDS...ALTHOUGH THE DETAILS REMAIN VERY UNCERTAIN.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR LOZ044-
045.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...TMA
LONG TERM...SMITH
AVIATION...APFFEL
MARINE...APFFEL/TMA
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
648 AM EST MON DEC 17 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE NORTHEAST ACROSS THE REGION THIS AFTERNOON
AND EVENING. HIGH PRESSURE WILL BUILD IN TUESDAY AND WEDNESDAY. A
STRONG COLD FRONT WILL SWEEP THROUGH THE AREA ON THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
WEAK COLD FRONT LIES A BIT NORTHWEST OF I-71 EARLY THIS MORNING.
THIS MAY CONTINUE TO SAG A BIT FURTHER SOUTH THROUGH THE MORNING.
SHOWERS HAVE BEEN OCCURRING TO THE SOUTH OF THE FRONT THROUGH MUCH
OF THE NIGHT. SHORT RANGE GUIDANCE SUGGESTS THAT THERE COULD BE A
BREAK IN THIS ACTIVITY AROUND DAYBREAK. BUT MORE SHOWERS WILL
SPREAD IN FROM THE SOUTHWEST AS A WAVE OF LOW PRESSURE TRACKS
ALONG THE FRONT.
APPEARS THAT THIS INITIAL WAVE WILL TAKE WIDESPREAD SHOWERS ACROSS
THE SOUTHEAST HALF OF THE AREA THROUGH EARLY AFTERNOON. ONCE AGAIN
THERE COULD BE A LULL IN ACTIVITY BEFORE MAIN SURFACE LOW
APPROACHES LATER IN THE DAY.
EXPECT THIS LOW TO TRACK A BIT FURTHER NORTH THAN THE INITIAL
WAVE. THUS SHOWERS WILL OCCUR ACROSS A GREATER PART OF THE
FORECAST AREA. SHOWERS WILL CONTINUE INTO THE EVENING BEFORE
TAPERING OFF LATER TONIGHT.
INSTABILITY WILL DEVELOP INTO THE SOUTHERN PORTION OF THE FORECAST
AREA THIS AFTERNOON AND EVENING. THUS SOME THUNDERSTORMS ARE
POSSIBLE. FORECAST SOUNDINGS FROM THE 00Z/06Z NAM DO NOT LOOK TOO
IMPRESSIVE. BUT LATEST RAP RUNS MANAGE A BIT MORE INSTABILITY.
CANNOT RULE OUT A FEW STRONGER STORMS MAINLY TO THE SOUTH OF
CINCINNATI LATE THIS AFTERNOON AND EARLY THIS EVENING.
CONCERNED THAT CLOUDS AND OCCASIONAL PRECIPITATION WILL LIMIT
TEMPERATURES. SO HAVE MOSTLY SHADED ON THE COOL SIDE OF GUIDANCE
FOR HIGHS. MOS LOOKED IN THE BALL PARK FOR LOWS.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
COULD BE A FEW LINGERING SHOWERS IN THE FAR EASTERN COUNTIES TO
START TUESDAY. BUT THE MAIN TREND WILL BE FOR HIGH PRESSURE TO
BUILD IN DURING THE PERIOD. A WEAK LOW WILL PASS ACROSS THE GREAT
LAKES TUESDAY NIGHT WHICH WILL TEMPORARILY SUPPRESS THE HIGH
SOMEWHAT. BUT THIS SHOULD ONLY BRING SOME CLOUDS TO THE NORTHERN
COUNTIES.
STAYED SLIGHTLY BELOW MOS FOR TUESDAY HIGHS. OTHERWISE A MOS BLEND
LOOKED REASONABLE FOR TEMPERATURES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A VIGOROUS SHORT WAVE WILL PIVOT NORTHEAST THROUGH THE REGION
DURING THE EARLY PART OF THE PERIOD. THIS WILL TAKE A DEEPENING
SURFACE LOW TO THE NORTHWEST OF THE FORECAST AREA. BUT A TRAILING
STRONG COLD FRONT WILL CROSS THE AREA ON THURSDAY. THERE ARE STILL
SOME SLIGHT TIMING DISCREPANCIES WITH THIS. HAVE GONE TOWARDS THE
SLIGHTLY SLOWER 00Z ECMWF WHICH HAS SUPPORT FROM THE 00Z CANADIAN.
SHOWERS WILL BE WIDESPREAD AHEAD OF THIS SYSTEM. THEY WILL SPREAD
INTO THE WESTERN COUNTIES LATE WEDNESDAY NIGHT AND MOVE ACROSS THE
ENTIRE AREA ON THURSDAY. TEMPERATURES WILL BE NON-DIURNAL. DO
EXPECT SOME DROP OFF IN READINGS WEDNESDAY EVENING BEFORE STARTING
TO RISE LATER IN THE NIGHT. TEMPERATURES WILL SHARPLY DROP AFTER
THE FRONTAL PASSAGE THURSDAY AFTERNOON. MODELS STILL NOT
DEVELOPING MUCH INSTABILITY WITH THIS. BUT WILL HAVE TO WATCH FOR
THUNDER POTENTIAL GIVEN STRONG DYNAMICS.
EXPECT WRAP AROUND SNOW SHOWERS WITH A BRIEF WINDOW FORM SOME LAKE
ENHANCEMENT THURSDAY NIGHT INTO FRIDAY. IN ADDITION...COLD
ADVECTION AND A STRONG PRESSURE GRADIENT WILL RESULT IN BLUSTERY
WINDS FROM AFTER FRONTAL PASSAGE RIGHT INTO FRIDAY. AS THE ENTIRE
SYSTEM LIFTS FURTHER AWAY FROM THE REGION THE WINDS WILL SUBSIDE
AND THE CHANCE OF SNOW SHOWERS WILL DIMINISH.
COLD HIGH PRESSURE CENTERED OVER THE UPPER MIDWEST WILL RIDGE
SOUTHEAST INTO THE REGION FOR THE WEEKEND. TEMPERATURES WILL BE AT
OR BELOW NORMAL FROM THURSDAY NIGHT THROUGH SUNDAY.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
A FRONTAL BOUNDARY CONTINUES TO BE POSITIONED FROM AROUND KCVG TO
KCMH. AN AREA OF LOW PRESSURE WILL MOVE NORTHEAST AND ACROSS THE
AREA TODAY AND ENHANCE RAIN SHOWER ACTIVITY. THIS AREA OF LOW
PRESSURE WILL BEGIN TO MOVE NE OF THE AREA TONIGHT AND RAIN WILL
COME TO AN END ACROSS THE FA.
CIGS ARE GENERALLY PRETTY LOW NW OF THE BOUNDARY WITH KDAY
EXPERIENCING LIFR CONDITIONS. SE OF THIS BOUNDARY MANY LOCATIONS
HAVE MVFR TO VFR CIGS AND VSBYS. WITH THIS BOUNDARY NEAR MANY OF
THE TAF SITES ANY SLIGHT MOVEMENT IN THE BOUNDARY COULD CAUSE A
CHANGE IN WIND SHIFT AND IN CIGS. TIMED OUT THE MOVEMENT OF THE
BOUNDARY IN THE TAFS AND THE SUBSEQUENT CHANGES IN THE CIG
FORECASTS.
KEPT THUNDER MENTION OUT OF THE TAFS FOR NOW AS THE BEST
INSTABILITY WILL REMAIN SOUTH OF THE TAF SITES.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES WILL BE POSSIBLE ON
TUESDAY. MVFR CONDITIONS ARE AGAIN EXPECTED ON THURSDAY. STRONG
WINDS ARE LIKELY THURSDAY AFTERNOON AND NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...NOVAK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
533 AM CST MON DEC 17 2012
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
329 AM CST MON DEC 17 2012
THE MAIN FOCUS FOR THE EARLY PORTION OF THE WEEK IS WITH THE
POTENTIAL FOR LIGHT SNOW ON TUESDAY FOLLOWED BY THE BEGINNING OF A
POSSIBLE WINTER STORM ON WEDNESDAY NIGHT.
CURRENTLY...EXTENSIVE CLOUD COVER REACHES FROM THE GREAT LAKES
THROUGH THE UPPER MISSISSIPPI RIVER VALLEY TO THE DAKOTAS BEFORE
CLEARING TO THE SOUTHWEST ALONG A WARM FRONT THAT EXTENDS FROM A
LOW IN FAR SOUTHEAST MONTANA THROUGH CENTRAL NEBRASKA. WINDS WILL
BE OUT OF THE NORTHWEST THROUGH MUCH OF TODAY WITH A SURFACE LOW
IN THE CENTRAL GREAT LAKES AND A RIDGE OF HIGH PRESSURE MOVING
ACROSS MINNESOTA. 17.00Z NAM/GFS AND 17.06Z RAP SOUNDINGS SHOW A
PERSISTENTLY STRONG INVERSION CENTERED ON 900MB THAT SHOULD KEEP
THE LOW LEVEL MOISTURE TRAPPED UNDERNEATH IT THROUGH THE DAY AND
SKIES ON THE CLOUDIER SIDE. THE SATURATED PORTION OF THIS PROFILE
DOES DIP DOWN TO AROUND -10C...SO THERE COULD BE SOME ICE THAT
DEVELOPS IF ANY LOW LEVEL LIFT CAN HELP TO PRODUCE SOME FLURRIES.
SOME RADAR RETURNS AND SURFACE OBS ARE REPORTING -SN OUT IN THE
SIOUX FALLS AREA CLOSER TO A WEAKENING AREA OF LOW PRESSURE...BUT
AM EXPECTING THAT AS THIS LOW TRIES TO RUN INTO THE RIDGE THAT IT
SHOULD LOSE MUCH OF ITS LOW LEVEL LIFT AND THAT THERE WONT BE MUCH
LEFT TO IT AS IT APPROACHES THE AREA.
A WEAK MID LEVEL SHORT WAVE TROUGH BREAKS TO THE EAST OF A CLOSED
LOW CURRENTLY IN THE PACIFIC NORTHWEST AND HELPS TO FORM AN
ELONGATED WEST TO EAST TROUGH THAT EXTENDS FROM THE DAKOTAS INTO
THE GREAT LAKES LATE TONIGHT INTO TOMORROW. THIS FEATURE WILL
PRODUCE SOME SLIGHTLY BETTER MID LEVEL LIFT THAT WILL BE AIDED BY
A PAIR OF SURFACE LOWS THAT WILL PROPAGATE EAST ALONG WITH IT. THE
NORTHERN SURFACE LOW WILL STICK TO THE DAKOTAS...BUT A SOUTHERN
LOW IS FORECAST TO TRACK ACROSS NORTHERN IOWA INTO SOUTHERN
WISCONSIN ON TUESDAY AND SHOULD PROVIDE SOME BETTER LIFT TO
DEVELOP A BAND OF PRECIPITATION TO THE NORTHEAST SIDE OF IT. THE
QG FORCING FROM THE MID LEVEL TROUGH APPEARS TO BE SLIGHTLY OFF
TIMING-WISE FROM THE LOW LEVEL FRONTOGENESIS TO WHERE THE
FORCING/MOISTURE IS NOT PARTICULARLY DEEP. THIS IS LIKELY WHY QPF
AMOUNTS ARE NOT MORE THAN A FEW HUNDREDTHS OF AN INCH WITH THIS
SYSTEM. SNOWFALL TOTALS WILL LIKELY BE SOMEWHERE IN THE HALF INCH
TO INCH RANGE WITH THE HIGHER TOTALS MORE LIKELY ACROSS SOUTHEAST
MINNESOTA AND WEST CENTRAL WISCONSIN WHERE THE PRECIPITATION TYPE
WILL REMAIN SNOW THROUGH THE DAY WHILE SOME RAIN COULD MIX IN
ACROSS NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN. THE DENDRITIC
GROWTH ZONE REMAINS FAIRLY SMALL AT LESS THAN A 100MB THROUGHOUT
THE DAY...SO AM NOT EXPECTING VERY HIGH SNOW TO LIQUID RATIOS FOR
THIS EVENT.
SKIES SHOULD CLEAR OUT TUESDAY NIGHT AS THE FRONT/TROUGH MOVES
THROUGH AND A RIDGE OF HIGH PRESSURE PUSHES IN FROM THE WEST. THIS
WILL SET THE STAGE FOR THE INITIAL STAGES OF A WINTER STORM THAT
WILL LIKELY AFFECT SOME OR ALL OF THE REGION. THE INITIAL BAND OF
PRECIPITATION WILL DEVELOP WEDNESDAY AFTERNOON ACROSS IOWA DUE TO
STRONG LOW LEVEL FRONTOGENETIC FORCING AS THE MAIN MID LEVEL
TROUGH ENTERS THE SOUTHERN PLAINS AND THE SURFACE LOW STARTS TO
DEEPEN IN THE SOUTHERN PLAINS. SOME DIFFERENCES ALREADY START TO
ARISE WEDNESDAY AFTERNOON BETWEEN THE 17.00Z MODEL RUNS WITH THE
ECMWF BEING THE SLOWEST TO BRING THE FRONTOGENETIC BAND INTO IOWA
WHILE THE GFS STRETCHES QPF ALL THE WAY INTO SOUTHWEST MICHIGAN.
THE NAM SHOWS A DRIER SOLUTION THAN WHAT THE GFS IS ADVERTISING
AND IS FURTHER TO THE WEST TO START OUT ON WEDNESDAY AFTERNOON.
WENT MAINLY WITH A 17.00Z GFS/ECMWF BLEND OVER THIS PERIOD AND
KEPT THE PRECIPITATION CHANCES MAINLY IN NORTHEAST IOWA. THE MID
LEVEL TROUGH THEN BEGINS TO CLOSE OFF WEDNESDAY NIGHT WITH THE
SURFACE LOW DEEPENING. THE OVERALL RESULT OF WHAT THE 17.00Z...AND
MANY PREVIOUS RUNS...PRODUCE IS A MAJOR WINTER STORM THAT MOVES
THROUGH THE GREAT LAKES REGION. THE QUESTION AT THIS POINT IS
WHERE THE CORE OF THE TROUGH/SURFACE LOW WILL TRACK.
TO START OUT...THE 17.00Z AND 17.06Z NAM ARE WARM/DEEP OUTLIERS IN
COMPARISON TO THE 17.00Z AND PREVIOUS RUNS OF THE ECMWF/GFS/GEM WITH
TAKING THE SURFACE LOW UP ALONG THE MISSISSIPPI RIVER. THE 17.06Z
RUN DOES APPEAR TO BE TRENDING A LITTLE TO THE EAST...BUT IS STILL
TOO FAR ON THE WEST SIDE OF THE TRACKS TO BE CONSIDERED. WITH MANY
OF THE SREF MEMBERS USING THE NAM...IT ALSO APPEARS TO BE HEAVILY
SKEWED BY IT AND IS TOO FAR WEST AS WELL WITH ITS QPF/LOW TRACK.
THE HIGHEST CONFIDENCE HAS TO BE PLACED WITH THE ECMWF WHICH HAS
BEEN NEARLY IDENTICAL FOR THE PAST 4 RUNS IN REGARD TO TIMING AND
PLACEMENT OF THE SURFACE LOW AND HEAVIEST SNOW BAND. THIS SOLUTION
TAKES THE LOW FROM ST LOUIS TOWARD NORTHERN INDIANA AND DETROIT
WITH THE HEAVIEST SNOW BAND GOING FROM EASTERN IOWA TO SOUTHEAST
WISCONSIN. THE GFS IS NOT TOO FAR OFF FROM THIS SOLUTION...BUT IS
A LITTLE FURTHER WEST OF THIS TRACK AND FASTER WITH THE LOW WHILE
THE GEM IS SOMEWHERE IN BETWEEN THE TWO.
FAVORED THE 17.00Z ECMWF WITH THIS FORECAST...SO WHILE CONFIDENCE
IS RATHER HIGH THAT THIS WINTER STORM WILL OCCUR...THE CONFIDENCE
IS NOT HIGH ENOUGH IN WHERE THE HEAVIEST SNOW BAND WILL END UP TO
ISSUE A LONG LEAD TIME WINTER STORM WATCH. PARTICULARLY SO SINCE
THE ECMWF TAKES THE HIGHER SNOW TOTALS TO THE EAST OF THE FORECAST
AREA. THE COUNTIES THAT ARE MOST LIKELY UNDER THE THREAT OF THE
HEAVIEST SNOWS ARE FROM JUNEAU/ADAMS COUNTIES IN WISCONSIN DOWN TO
CLAYTON COUNTY IN IOWA BASED ON THESE 17.00Z ECMWF/GFS/GEM
RESULTS.
.LONG TERM...THURSDAY THROUGH SUNDAY
329 AM CST MON DEC 17 2012
THE STORM WILL CONTINUE INTO THURSDAY...BUT HOW FAR WEST THE SNOW
LINGERS IS THE MAIN QUESTION. PERHAPS THE BIGGER ISSUE WILL BE
WITH THE STRONG WINDS THAT ACCOMPANY THIS STORM THAT SHOULD LEAD
TO SOME BLOWING SNOW WITH SUSTAINED WINDS REACHING 25 MPH AND
LIKELY GUSTING ABOVE 30 MPH. BY THURSDAY NIGHT...THE STORM WILL
LIKELY HAVE ENDED ACROSS WESTERN WISCONSIN WITH HIGH PRESSURE
PUSHING DOWN FROM SOUTH CENTRAL CANADA. THIS RIDGE WILL REMAIN IN
PLACE THROUGH NEXT WEEKEND AND WILL...ALONG WITH THE FRESH
SNOW PACK...PROVIDE FOR COLD AND DRY CONDITIONS WITH LOWS DROPPING
DOWN INTO THE SINGLE DIGITS.
&&
.AVIATION...TODAY AND TONIGHT
531 AM CST MON DEC 17 2012
LOW CLOUDS WILL REMAIN TRAPPED BELOW A SUBSIDENCE INVERSION
THROUGH EARLY THIS EVENING. CEILINGS WILL CONTINUE TO BE LIFR/IFR AT
KRST AND MVFR AT KLSE. AS A LOW PRESSURE SYSTEM APPROACHES THE
REGION...THE INVERSION WILL BREAK BETWEEN 18.02Z AND 18.08Z. THIS
WILL RESULT IN THE CEILINGS CLIMBING INTO THE 4 TO 5K RANGE FOR A
COUPLE OF HOURS...AND THEN ONCE AGAIN BECOME MVFR AS THE CLOUDS
LOWER AHEAD OF APPROACHING LOW PRESSURE SYSTEM.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
329 AM CST MON DEC 17 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
334 PM MST MON DEC 17 2012
.SHORT TERM...WEB CAMS SHOWING SNOW ACROSS MOUNTAINS
CONTINUING...THOUGH A BIT IMPROVEMENT IN THE LAST FEW HOURS. ALSO
SOME GUSTS AROUND 50 MPH ALONG THE DIVIDE...WHICH HAS BEEN
CREATING AREAS OF BLOWING AND DRIFITING SNOW. LATEST SNOWTELL OBS
SUGGESTING ABOUT 6 INCHES OF SNOW HAD FALLEN ACROSS ZONE 31 IN THE
LAST 6 HOURS...WITH PERHAPS 2 TO 4 INCHES FOR ZONES 33 AND 34.
ACROSS FOOTHILLS AND ALONG URBAN CORRIDOR...WESTERLY WINDS GUSTING
IN THE 30-40 MPH RANGE MOST AREAS. STRONG PACIFIC JET STILL
EXPECTED TO MOVE ACROSS NORTHERN COLORADO DURING THE EVENING AND
OVERNIGHT WITH STRONGER WINDS LOWERING TO NEAR MOUNTAIN TOP. MODEL
CROSS SECTIONS INDICATING INCREASING LAPSE RATES ALONG WITH MID
LEVEL ASCENT. SHOULD SEE MOUNTAIN SNOW BEGIN TO INCREASE AGAIN
DURING THE EVENING AS THE LIFT INCREASES. LOCAL SNOW MODEL STILL
YIELDING ROUGHLY 5-10 INCHES ACROSS ZONE 31 TONIGHT...WITH AROUND
4-8 INCHES FOR ZONES 33 AND 34. THIS LOOKS REASONABLE BUT MAY NEED
TO ADD A FEW INCHES FOR THE DYNAMICS. FEEL CURRENT WARNING FOR
ZONE 31 AND ADVISORY FOR 33 STILL ON TRACK. BUT WILL ALSO INCLUDE
ZONE 34 IN THE ADVISORY...THOUGH AMOUNTS MAY NOT MEET CRITERIA
THERE WILL BE SUFFICIENT BLOWING SNOW. ACROSS PLAINS SHOULD SEE
WINDS BEGIN TO DECOUPLE THOUGH WILL REMAIN A BIT GUSTY NEAR THE
FOOTHILLS. LATEST RUC SHOWS SOME LIGHT PRECIP ACROSS ZONE 38 THIS
EVENING...STILL LOOKS REASONABLE WITH THE APPROACHING LIFT. ON
TUESDAY...FLOW ALOFT WEAKENS A BIT AS THE JET CORE HEADS EAST AND
BECOMES MORE SOUTHWEST AS AN UPPER TROUGH APPROACHES THE GREAT
BASIN. WILL STILL BE A BIT GUSTY ACROSS THE RIDGES. SOUTHWEST
FLOW NOT FAVORABLE FOR DECENT MOUNTAIN SNOWFALL. MID LEVEL QG
ACENT ALSO DECREASES. WOULD EXPECT SNOW TO CONTINUE WITH FAIRLY
GOOD MOISTURE...BUT SHOULD BE LIGHT. WILL NOT EXTEND HILITES
BEYOND 12Z. ACROSS PLAINS...SURFACE WINDS TO BECOME EASTERLY WITH
THE DEVELOPMENT OF AN ANTICYCLONE. LATEST GFS AND ECMWF SHOWS SOME
LIGHT QPF DURING THE AFTERNOON...MAY BE A BIT OVERDONE AS LOW
LEVEL STILL LOOK DRY.
.LONG TERM...MODELS CONTINUE TO ADVERTISE A SIGNIFICANT WINTER
WEATHER EVENT ACROSS THE FORECAST AREA ON WEDNESDAY. FROM TUESDAY
EVENING THROUGH WEDNESDAY EVENING AN UPPER TROUGH WILL BE MOVING
OVER THE STATE WHILE A SURFACE LOW OVER SOUTHEAST COLORADO
UNDERGOES STRONG CYCLOGENESIS. A STRONG COLD FRONT WILL MOVE OVER
NORTHERN COLORADO...INCLUDING THE MOUNTAINS...TUESDAY EVENING.
UPSLOPE WINDS WILL THEN CONTINUE THROUGH THE PRE-DAWN HOURS AND
STRENGTHEN THROUGH THE DAY WEDNESDAY. THE UPPER TROUGH WILL
CONTAIN PLENTY OF DYNAMICS ACCORDING TO THE Q-G DIAGNOSTICS
PACKAGE. THE PRESENCE OF THE STRONG UPPER LEVEL JET OVER THE PAST
FEW DAYS MAKE THE MODEL SOLUTIONS VERY BELIEVABLE. THE NAM QPF
AMOUNTS ARE A FAIR AMOUNT HIGHER THAN THE GFS AND ECMWF SOLUTIONS
CONCERNING HOW MUCH SNOW WE GET ON WEDNESDAY. ALL MODELS AGREE
QUITE A BIT OF WIND DEVELOPING. WITH THE THREAT OF SIGNIFICANT
BLOWING SNOW BECAUSE OF THE WIND...WILL ISSUE A WINTER STORM WATCH
ACROSS THE PLAINS. SNOW AMOUNTS OF 3 TO 6 INCHES WILL BE TOO LIGHT
IF THE NAM IS RIGHT. WIND GUSTS OF 25 TO 40 MPH MIGHT BE COMMON AT
THE HEIGHT OF THE STORM. PERIODS OF SNOW WILL BE ONGOING IN THE
MOUNTAINS DUE TO THE DYNAMICS OVER THE STATE.
THE UPPER TROUGH WILL BE MOVING EAST OF COLORADO BY WEDNESDAY
EVENING WHICH WILL BRING A RAPID END TO THE SNOW EVENT. LINGERING
SHOWERS IN THE EVENING WILL COME TO AN END OVERNIGHT. FOR THE
PERIOD THURSDAY THROUGH SUNDAY...STRONG UPPER RIDGING WILL BE OVER
THE STATE WITH DRY WEATHER FROM THE MOUNTAINS EASTWARD WITH
TEMPERATURES TRENDING TOWARD SEASONAL NORMALS.
EARLY NEXT WEEK LOOKS LIKE ANOTHER TROUGH MAY BE APPROACHING THE
STATE IF THE ECMWF IS CORRECT. FOR THE TIME BEING WILL JUST
MENTION AN INCREASING CHANCE OF SNOW IN THE MOUNTAINS AS THE STATE
COMES UNDER THE SOUTHWESTERLY FLOW AHEAD OF THE TROUGH.
&&
.AVIATION...WESTERLY WINDS TO CONTINUE ACROSS THE DENVER
AREA THROUGH 02Z...WITH SOME GUSTS TO TO 35 KTS. WINDS TO DECREASE
AT DEN AND APA AND BECOME SOUTHWESTERLY DURING THE EVENING BUT
SHOULD REMAIN WESTERLY AND GUSTY AT BJC. AFTER 15Z TUESDAY...
MODELS SHOW THE DEVELOPMENT OF AN ANTICYCLONE IN THE DENVER
AREA...WITH WIND BECOMING EASTERLY. VFR TO CONTINUE WITH NO
PRECIPITATION EXPECTED.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TUESDAY NIGHT THROUGH WEDNESDAY
AFTERNOON FOR COZ038>051.
WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY FOR COZ034.
WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY FOR COZ033.
WINTER STORM WARNING UNTIL 5 AM MST TUESDAY FOR COZ031.
&&
$$
SHORT TERM...D-L
LONG TERM....DANKERS
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1007 AM MST MON DEC 17 2012
.UPDATE...
&&
.SHORT TERM...WEB CAMS ACROSS MOUNTAINS SHOWING SNOW CONTINUING...
WITH SOME SIGNS OF INCREASING IN THE STEAMBOAT AREA AS WELL AS
ACROSS THE HIGHER ELEVATIONS OF GRAND...BOULDER AND LARIMER
COUNTIES. WILL MAINTAIN THE CURRENT HILITES FOR ZONES 31 AND 33
THOUGH NOT EXPECTING MUCH ACCUMULATION THROUGH THIS AFTERNOON.
WINDS HAVE ALSO BEEN STEADILY INCREASING AS CROSS MOUNTAIN
PRESSURE GRADIENT INCREASES...WITH 1500M GJT-DEN GRADIENT AT 9.53
MB. BOTH RUC AND NAM CONTINUE TO SHOW WINDS ACROSS MOUNTAINS AND
FOOTHILLS INCREASING THROUGH THE DAY AS NOSE OF STRONG PACIFIC JET
MOVES INTO NORTHWEST COLORADO. RUC CROSS SECTIONS INDICATE 50 KTS
OF CROSS MOUNTAIN FLOW MOVING DOWN THE LEE SLOPES OF THE FOOTHILLS
BY 20Z. SHOULD CONTINUE TO SEE AN INCREASE IN WINDS OVER THE
MOUNTAINS AND ALONG THE FOOTHILLS WITH WINDS SPREADING ACROSS THE
PLAINS. AT THIS TIME...NOT EXPECTING WINDS REACHING HIGH WIND
CRITERIA AS LAPSE RATES BEGIN TO INCREASE AND LIMIT STABILITY.
OVERALL...CURRENT FORECASTS STILL SEEM ON TRACK. LATEST RAP SHOWS
SOME LIGHT QPF ACROSS NORTHERN PLAINS AFTER 20Z IN AREA OF FAVORED
LIFT ASSOCIATED WITH THE APPROACHING JET. MAY NEED TO INCLUDE THE
FAR NORTHEAST CORNER.
.AVIATION...GUSTY WESTERLY WINDS TO CONTINUE TO BE THE MAIN
CONCERN ACROSS THE DENVER AREA THIS AFTERNOON AND EVENING. CURRENT
TAF TREND STILL SEEM ON TRACK WITH GUSTS TO 40 KTS POSSIBLE. MAY
NEED TO KEEP MORE OF A SOUTHWEST COMPONENT FOR A FEW HOURS PER
RUC AND NAM.
&&
.PREV DISCUSSION... /ISSUED 456 AM MST MON DEC 17 2012/
SHORT TERM...WE/RE SETTING UP FOR A VERY WINDY 12-18HRS IN THE
HIGH COUNTRY AND FRONT RANGE FOOTHILLS. ALREADY SEEING WLY SFC
WINDS GUSTING IN THE 50-55 MPH RANGE AT A NUMBER OF HIGH MTN
MONITORING SITE. THE CROSS MTN PRES GRADIENT CONTINUES TO
INCREASE WITH A 8MB DEN-GJT GRADIENT AT THIS HOUR...AND THE RUC
WAS ALSO INDICATING A STRENGTHENING MTN TOP STABLE LAYER WITH
SLIGHT WARMING ALOFT. IN ADDITION...BOTH THE RUC AND NAM SHOW A
LEE SIDE MTN WAVE AMPLYING THROUGH THE DAY. AS THIS IS GOING
ON...MODELS SHOW THE NOSE OF A POWERFUL PACIFIC JET REACHING
NWRN COLORADO THIS AFTERNOON...AND TRAVERSING THE NRN HALF OF
THE STATE OVERNIGHT WITH THE ARRIVAL OF EVEN STRONGER WINDS AT ITS
CORE. ITS OVERNIGHT WHEN MODELS SHOW THESE ESPLY STRONG WINDS
LOWERING IN ALTITUDE TO NEAR MTN TOP LEVEL. NOT OUT OF THE
QUESTION THAT WINDS ABOVE TIMBERLINE COULD EXCEED 70 MPH CREATING
SERIOUS WHITEOUT CONDITIONS. HOW FAR SOUTH MIGHT WE EXPECT ALL
THIS. AT THIS TIME IT WOULD APPEAR MTN AREAS ROUGHLY ALONG AND
NORTH OF INTERSTATE 70 WILL BE GROUND ZERO. MTN ZONE 31 IS
PRESENTLY UNDER A WINTER STORM WARNING..AND NRN MTN ZONE 33 A
WINTER WEATHER ADVISORY. NO CHANGES TO CURRENT HIGHLIGHTS AT THIS
TIME EVEN THOUGH FEW N-CENTRAL MTN LOCALES REPORTING ACCUMULATING
SNOWFALL ATTM...WITH ONLY LIGHT SNOWFALL UP AT EISENHOWER TUNNEL
VIA CDOT MTN CAMS. DO NOT SEE MUCH IN THE WAY OF SNOW
ACCUMULATION IN THE HIGH COUNTRY THIS MORNING AND POSSIBLY INTO
EARLY AFTERNOON WITH POOR LAPSE RATES OVER THE AREA. ITS LATE
THIS AFTERNOON AS WINDS INCREASE THAT THE INSTABILITY INCREASES
AND MOISTURE DEEPENS ACCORDING TO MODEL SOUNDINGS AND CROSS
SECTIONS. BUT ITS OVERNIGHT WHEN EVERYTHING COMES TOGETHER FOR A
NASTY SITUATION IN THE HIGH COUNTRY. THE WINTER WEATHER ADVISORY
FOR ZONE 34 MAY NEED TO BE UPGRADED TO A STORM WARNING OR POSSIBLY
A BLIZZARD WARNING SHOULD WINDS AND SNOWFALL BECOME GREATER THAN
NOW EXPECTED. MAY ALSO NEED TO ADD MTN ZONE 34 TO HIGHLIGHTS IF
THE CORE OF THE JET SAGS FARTHER SOUTH.
MEANWHILE...ON THE PLAINS WESTERLY FLOW OFF THE FRONT RANGE WILL
WARM TEMPS WELL ABOVE AVERAGE TODAY...PARTICULARLY IN THE WINDIER
AREA ALONG THE BASE OF THE FOOTHILLS. COULD SEE GUSTS IN THE 30-40
MPH IN THE CHINOOK ZONE WEST OF I-25 AND 15-30 MPH FARTHER OUT
ACROSS THE PLAINS. SFC WINDS ON THE PLAINS EXPECTED TO DECOUPLE
FROM THE 130+KT WINDS ALOFT THIS EVENING. PLAINS WILL ALSO REMAIN
DRY THROUGH ALL THIS...EXCEPT PERHAPS UP ALONG THE WYOMING BORDER
WHERE A FEW SNOW SHWRS MAY MOVE OFF THE FOOTHILLS OVERNIGHT.
LONG TERM...MAIN CONCERN WILL BE CONTINUED WIND AND SNOW IN THE
MOUNTAINS ON TUESDAY...AND THEN DEVELOPING SNOW AND COLDER
TEMPERATURES ON THE PLAINS LATE TUESDAY NIGHT AND WEDNESDAY. AS
FORECAST CONFIDENCE INCREASES WITH CONSISTENT MODEL SOLUTIONS IT
APPEARS THIS WILL BE THE FIRST WIDESPREAD SNOW EVENT SINCE EARLIER
THIS FALL. FOR TUESDAY..MOISTURE DEPTH IS RATHER SHALLOW IN THE
MOUNTAINS SO EXPECT MAINLY LIGHT SNOWFALL DURING THE DAY. MOISTURE
DEPTH INCREASES LATE TUESDAY AND TUESDAY NIGHT AS THE MAIN UPPER
TROF APPROACHES COLORADO AND THEN MOVES ACROSS THE STATE ON
WEDNESDAY AS A STRONG OPEN WAVE. QG FIELDS SHOWING FAIRLY STRONG
UPWARD ASCENT AS THE TROF PASSES BY. SURFACE LOW PRESSURE WILL BE
DEEPENING TUESDAY NIGHT ACROSS SOUTHEAST COLORADO WHICH WILL
INCREASE WINDS FROM THE NORTH AND NORTHEAST AND AIRMASS SATURATES.
COMPILATION OF MODELS SHOWING ANYWHERE FROM 2-6 INCHES OF SNOW
OVER THE PLAINS BY LATE WEDNESDAY GIVEN A PERIOD OF 8-12 HOURS OF
SNOWFALL. GIVEN THE AMOUNT OF WINDS WOULD EXPECT WINTER WEATHER
ADVISORIES MAY BE NEEDED AT SOME POINT ON THE PLAINS BUT STILL
HAVE TO TIME TO NARROW DOWN THE DETAILS.
THE SNOW WILL DECREASE WEDNESDAY AFTERNOON WITH GRADUAL CLEARING
EXPECTED WEDNESDAY NIGHT ACROSS THE STATE. CROSS SECTIONS
INDICATING STRONGER WINDS DEVELOPING AGAIN BEHIND THE TROF OVER
THE MOUNTAINS AND EAST SLOPES. THIS MAY RESULT IN ISSUES WITH
BLOWING SNOW OVER THE FOOTHILLS AND ADJACENT PLAINS. LOOKING FOR A
DRY PERIOD WITH MODERATING TEMPERATURES FOR THURSDAY THROUGH THE
WEEKEND. AS A SIDE NOTE...LONG RANGE MODELS ARE SHOWING ANOTHER
POSSIBLE STORM DEVELOPING AROUND CHRISTMAS GIVE OR TAKE A DAY ON
EITHER SIDE. STILL A LOT OF VARYING SOLUTIONS SO WON`T GET TOO
EXCITED YET.
AVIATION...WINDS MAIN CONCERN IN THE DENVER AREA TODAY. BJC NEAR
THE FOOTHILLS ALREADY SEEING PERIODIC WEST WINDS OF 20-25KTS.
WINDS EVEN STRONGER THAN THIS LIKELY TO BECOME MORE PERSIST AT
BJC AS THE MORNING PROGRESSES WITH WLY GUSTS APCHG 45KTS BY
AFTERNOON. SLY WINDS AT DIA AND APA ALSO EXPECTED TO PICK UP IN
THE NEXT FEW HRS AS THEY SHIFT TO A WESTERLY COMPONENT. COULD SEE
GUSTS IN THE 20-35KTS AT BOTH AIRPORTS BY MID TO LATE
AFTERNOON...AND THROUGHOUT THE AFTERNOON. NO PRECIP AT THIS
TIME...SO VFR CIGS AND VSBYS. BY NIGHTFALL SHOULD SEE A STEADY
DROP OF IN WINDS AT DIA AND APA...BUT GUSTY WLY WINDS LIKELY TO
CONTINUE AT BJC FOR MUCH OF THE EVENING.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 5 AM MST TUESDAY FOR COZ031.
WINTER WEATHER ADVISORY UNTIL 5 AM MST TUESDAY FOR COZ033.
&&
$$
SHORT TERM...D-L
LONG TERM....ENTREKIN
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
328 PM EST MON DEC 17 2012
.SYNOPSIS...
AN APPROACHING COLD FRONT WILL MOVE THROUGH THE FORECAST AREA
TONIGHT. SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL OCCUR
AHEAD OF THE FRONT. DRY HIGH PRESSURE BEHIND THE FRONT WILL
DOMINATE TUESDAY AND WEDNESDAY. ANOTHER COLD FRONT WILL MOVE INTO
THE AREA THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
SHOWERS HAVE OVERSPREAD THE FORECAST AREA ASSOCIATED WITH THE H85
JET. SURFACE-BASED INSTABILITY WAS CONFINED TO SOUTH GEORGIA
WHERE EARLY AFTERNOON LI VALUES WERE NEAR -2. THE NAM FORECAST OF
LI/S LOWERING TO NEAR -4 IN THE FORECAST AREA DURING THE AFTERNOON
APPEARS OVERDONE. INSTABILITY SHOULD REMAIN LIMITED BECAUSE OF
CLOUDINESS AND WIDESPREAD RAIN. THE RAP APPEARS MORE REASONABLE
WITH POSITIVE LI/S THROUGH THE AFTERNOON WITH GREATER INSTABILITY
THIS EVENING AFTER THE MOISTURE BECOMES SHALLOW AND MORE COOLING
ALOFT OCCURS AS THE UPPER TROUGH MOVES INTO THE AREA. SEVERE
THUNDERSTORMS ARE NOT OUT OF THE QUESTION BECAUSE OF HIGH SHEAR
BUT WE BELIEVE THE CHANCE IS LOW BECAUSE OF A LACK OF SURFACE-
BASED INSTABILITY. SHOWERS SHOULD END FROM WEST TO EAST AS THE
DEEPER MOISTURE AND H85 JET AHEAD OF THE FRONT SHIFTS EAST OF THE
AREA THIS EVENING. MIXING ASSOCIATED WITH THE FRONT SHOULD HELP HOLD UP
TEMPERATURES TONIGHT. WE USED THE WARMER TEMPERATURE GUIDANCE.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
DRY HIGH PRESSURE BEHIND THE COLD FRONT WILL DOMINATE TUESDAY
THROUGH WEDNESDAY NIGHT. STRONG RADIATIONAL COOLING WILL OCCUR
TUESDAY NIGHT. THE TEMPERATURE GUIDANCE WAS CLOSE THROUGH THE
PERIOD.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
THE GFS AND ECMWF SHOW A COLD FRONT IN THE FORECAST AREA THURSDAY
OR THURSDAY NIGHT. THE MODELS SHOW STRONG SHEAR ASSOCIATED WITH
THIS FRONT WITH H85 WINDS NEAR 60 KNOTS. THUNDERSTORMS WITH
DAMAGING WIND COULD POSSIBLY OCCUR ALTHOUGH INSTABILITY SHOULD BE
A LIMITING FACTOR. DRY HIGH PRESSURE BEHIND THIS FRONT SHOULD
DOMINATE DURING THE REST OF THE MEDIUM-RANGE PERIOD.
&&
.AVIATION /21Z MONDAY THROUGH SATURDAY/...
HIGHLY VARIABLE CONDITIONS CONTINUE ACROSS THE TAF SITES...WITH MVFR
AND IFR EXPECTED TO DOMINATE THE PERIOD.
COLD FRONT MAKING SLOW PROGRESS ACROSS THE WESTERN GULF REGION. AN
AREA OF SHOWER ALONG WITH SOME THUNDERSTORMS ACROSS EXTREME SRN GA
AND THE PANHANDLE OF FL WILL CONTINUE TO MOVE NORTHEAST THROUGHOUT
THE AFTERNOON. SATELLITE IMAGERY SHOWS PLENTY OF CLOUDS ACROSS THE
AREA AND PLENTY MORE UPSTREAM...SO EXPECT CLOUDY CONDITIONS FOR MUCH
OF THE TAF PERIOD. HAVE CONTINUED WITH RAIN IN THE FORECAST THROUGH
THE AFTERNOON...HOWEVER HAVE NOT INCLUDED THUNDER. EXPECT
THUNDERSTORMS TO REMAIN SOUTH AND EAST OF THE TERMINALS WHERE
AIR MASS IS UNSTABLE. THE RAIN WILL BEGIN TO DIMINISH ACROSS THE
AREA THIS EVENING INTO TONIGHT...HOWEVER WITH PLENTY OF MOISTURE
AND 30 TO 40 KT LOW LEVEL JET EXPECT LOW CLOUDS AND FOG TO LINGER
LATE INTO THE PERIOD. ON TUESDAY...EXPECT CLEARING TO BEGIN RATHER
QUICKLY AS TIGHT SURFACE PRESSURE GRADIENT BETWEEN DEPARTING FRONT
AND HIGH BUILDING IN FROM THE WEST WILL PRODUCE BREEZY CONDITIONS
BEGINNING AROUND 15Z.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS AGAIN POSSIBLE THURSDAY
MORNING INTO FRIDAY MORNING AS ANOTHER COLD FRONT CROSSES THE
REGION. BREEZY CONDITIONS POSSIBLE THURSDAY NIGHT AND FRIDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
214 PM EST MON DEC 17 2012
.SYNOPSIS...
AN APPROACHING COLD FRONT WILL MOVE THROUGH THE FORECAST AREA
TONIGHT. SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL OCCUR
AHEAD OF THE FRONT. DRY HIGH PRESSURE BEHIND THE FRONT WILL
DOMINATE TUESDAY AND WEDNESDAY. ANOTHER COLD FRONT WILL MOVE INTO
THE AREA THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SHOWERS HAVE OVERSPREAD THE FORECAST AREA ASSOCIATED WITH THE H85
JET. SURFACE-BASED INSTABILITY WAS CONFINED TO SOUTH GEORGIA
WHERE EARLY AFTERNOON LI VALUES WERE NEAR -2. THE NAM FORECAST OF
LI/S LOWERING TO NEAR -4 IN THE FORECAST AREA DURING THE AFTERNOON
APPEARS OVERDONE. INSTABILITY SHOULD REMAIN LIMITED BECAUSE OF
CLOUDINESS AND WIDESPREAD RAIN. THE RAP APPEARS MORE REASONABLE
WITH POSITIVE LI/S THROUGH THE AFTERNOON WITH GREATER INSTABILITY
THIS EVENING AFTER THE MOISTURE BECOMES SHALLOW AND MORE COOLING
ALOFT OCCURS AS THE UPPER TROUGH MOVES INTO THE AREA. SEVERE
THUNDERSTORMS ARE NOT OUT OF THE QUESTION BECAUSE OF HIGH SHEAR
BUT WE BELIEVE THE CHANCE IS LOW BECAUSE OF A LACK OF SURFACE-
BASED INSTABILITY. SHOWERS SHOULD END FROM WEST TO EAST AS THE
DEEPER MOISTURE AND H85 JET AHEAD OF THE FRONT SHIFTS EAST OF THE
AREA THIS EVENING. MIXING ASSOCIATED WITH THE FRONT SHOULD HELP HOLD UP
TEMPERATURES TONIGHT. WE USED THE WARMER TEMPERATURE GUIDANCE.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
DRY HIGH PRESSURE BEHIND THE COLD FRONT WILL DOMINATE TUESDAY
THROUGH WEDNESDAY NIGHT. STRONG RADIATIONAL COOLING WILL OCCUR
TUESDAY NIGHT. THE TEMPERATURE GUIDANCE WAS CLOSE THROUGH THE
PERIOD.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
THE GFS AND ECMWF SHOW A COLD FRONT IN THE FORECAST AREA THURSDAY
OR THURSDAY NIGHT. THE MODELS SHOW STRONG SHEAR ASSOCIATED WITH
THIS FRONT WITH H85 WINDS NEAR 60 KNOTS. THUNDERSTORMS WITH
DAMAGING WIND COULD POSSIBLY OCCUR ALTHOUGH INSTABILITY SHOULD BE
A LIMITING FACTOR. DRY HIGH PRESSURE BEHIND THIS FRONT SHOULD
DOMINATE DURING THE REST OF THE MEDIUM-RANGE PERIOD.
&&
.AVIATION /19Z MONDAY THROUGH SATURDAY/...
HIGHLY VARIABLE CONDITIONS CONTINUE ACROSS THE TAF SITES...WITH MVFR
AND IFR EXPECTED TO DOMINATE THE PERIOD.
COLD FRONT MAKING SLOW PROGRESS ACROSS THE WESTERN GULF REGION. AN
AREA OF SHOWER ALONG WITH SOME THUNDERSTORMS ACROSS EXTREME SRN GA
AND THE PANHANDLE OF FL WILL CONTINUE TO MOVE NORTHEAST THROUGHOUT
THE AFTERNOON. SATELLITE IMAGERY SHOWS PLENTY OF CLOUDS ACROSS THE
AREA AND PLENTY MORE UPSTREAM...SO EXPECT CLOUDY CONDITIONS FOR MUCH
OF THE TAF PERIOD. HAVE CONTINUED WITH RAIN IN THE FORECAST THROUGH
THE AFTERNOON...HOWEVER HAVE NOT INCLUDED THUNDER AS CONFIDENCE IS
LOW AT THIS TIME FOR OCCURRENCE AT ANY TAF SITES. THE BEST CHANCE
FOR THUNDER WOULD BE THE SOUTHERN/EASTERN TAFS CLOSER TO THE MORE
UNSTABLE CONDITIONS...AGS/DNL/OGB. THE RAIN WILL BEGIN TO DIMINISH
ACROSS THE AREA THIS EVENING INTO TONIGHT...HOWEVER WITH PLENTY OF
MOISTURE AND 30 TO 40 KT LOW LEVEL JET EXPECT LOW CLOUDS AND FOG TO
LINGER LATE INTO THE PERIOD. ON TUESDAY...EXPECT CLEARING TO BEGIN
RATHER QUICKLY AS TIGHT SURFACE PRESSURE GRADIENT BETWEEN DEPARTING
FRONT AND HIGH BUILDING IN FROM THE WEST WILL PRODUCE BREEZY
CONDITIONS BEGINNING AROUND 15Z.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS AGAIN POSSIBLE THURSDAY
MORNING INTO FRIDAY MORNING AS ANOTHER COLD FRONT CROSSES THE
REGION. BREEZY CONDITIONS POSSIBLE THURSDAY NIGHT AND FRIDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
119 PM EST MON DEC 17 2012
.SYNOPSIS...
AN APPROACHING COLD FRONT WILL MOVE THROUGH THE FORECAST AREA
TONIGHT. SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL OCCUR
AHEAD OF THE FRONT. DRY HIGH PRESSURE BEHIND THE FRONT WILL
DOMINATE TUESDAY AND WEDNESDAY. ANOTHER COLD FRONT WILL MOVE INTO
THE AREA THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SHOWERS HAVE OVERSPREAD THE FORECAST AREA ASSOCIATED WITH THE H85
JET. SURFACE-BASED INSTABILITY WAS CONFINED TO SOUTH GEORGIA
WHERE EARLY AFTERNOON LI VALUES WERE NEAR -2. THE NAM FORECAST OF
LI/S LOWERING TO NEAR -4 IN THE FORECAST AREA DURING THE AFTERNOON
APPEARS OVERDONE. INSTABILITY SHOULD REMAIN LIMITED BECAUSE OF
CLOUDINESS AND WIDESPREAD RAIN. THE RAP APPEARS MORE REASONABLE
WITH POSITIVE LI/S THROUGH THE AFTERNOON WITH GREATER INSTABILITY
THIS EVENING AFTER THE MOISTURE BECOMES SHALLOW AND MORE COOLING
ALOFT OCCURS AS THE UPPER TROUGH MOVES INTO THE AREA. SEVERE
THUNDERSTORMS ARE NOT OUT OF THE QUESTION BECAUSE OF HIGH SHEAR
BUT WE BELIEVE THE CHANCE IS LOW BECAUSE OF A LACK OF SURFACE-
BASED INSTABILITY. SHOWERS SHOULD END FROM WEST TO EAST AS THE
DEEPER MOISTURE AND H85 JET AHEAD OF THE FRONT SHIFTS EAST OF THE
AREA THIS EVENING. MIXING ASSOCIATED WITH THE FRONT SHOULD HELP HOLD UP
TEMPERATURES TONIGHT. WE USED THE WARMER TEMPERATURE GUIDANCE.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
DRY HIGH PRESSURE BEHIND THE COLD FRONT WILL DOMINATE TUESDAY
THROUGH WEDNESDAY NIGHT. STRONG RADIATIONAL COOLING WILL OCCUR
TUESDAY NIGHT. THE TEMPERATURE GUIDANCE WAS CLOSE THROUGH THE
PERIOD.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
THE GFS AND ECMWF SHOW A COLD FRONT IN THE FORECAST AREA THURSDAY
OR THURSDAY NIGHT. THE MODELS SHOW STRONG SHEAR ASSOCIATED WITH
THIS FRONT WITH H85 WINDS NEAR 60 KNOTS. THUNDERSTORMS WITH
DAMAGING WIND COULD POSSIBLY OCCUR ALTHOUGH INSTABILITY SHOULD BE
A LIMITING FACTOR. DRY HIGH PRESSURE BEHIND THIS FRONT SHOULD
DOMINATE DURING THE REST OF THE MEDIUM-RANGE PERIOD.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
HIGHLY VARIABLE CONDITIONS CONTINUE ACROSS THE TAF SITES...WITH MVFR
AND IFR EXPECTED TO DOMINATE THE PERIOD.
COLD FRONT MAKING SLOW PROGRESS ACROSS THE WESTERN GULF REGION. AN
AREA OF SHOWER ALONG WITH SOME THUNDERSTORMS ACROSS EXTREME SRN GA
AND THE PANHANDLE OF FL WILL CONTINUE TO MOVE NORTHEAST THROUGHOUT
THE AFTERNOON. SATELLITE IMAGERY SHOWS PLENTY OF CLOUDS ACROSS THE
AREA AND PLENTY MORE UPSTREAM...SO EXPECT CLOUDY CONDITIONS FOR MUCH
OF THE TAF PERIOD. HAVE CONTINUED WITH RAIN IN THE FORECAST THROUGH
THE AFTERNOON...HOWEVER HAVE NOT INCLUDED THUNDER AS CONFIDENCE IS
LOW AT THIS TIME FOR OCCURRENCE AT ANY TAF SITES. THE BEST CHANCE
FOR THUNDER WOULD BE THE SOUTHERN/EASTERN TAFS CLOSER TO THE MORE
UNSTABLE CONDITIONS...AGS/DNL/OGB. THE RAIN WILL BEGIN TO DIMINISH
ACROSS THE AREA THIS EVENING INTO TONIGHT...HOWEVER WITH PLENTY OF
MOISTURE AND 30 TO 40 KT LOW LEVEL JET EXPECT LOW CLOUDS AND FOG TO
LINGER LATE INTO THE PERIOD. ON TUESDAY...EXPECT CLEARING TO BEGIN
RATHER QUICKLY AS TIGHT SURFACE PRESSURE GRADIENT BETWEEN DEPARTING
FRONT AND HIGH BUILDING IN FROM THE WEST WILL PRODUCE BREEZY
CONDITIONS BEGINNING AROUND 15Z.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS AGAIN POSSIBLE THURSDAY
MORNING INTO FRIDAY MORNING AS ANOTHER COLD FRONT CROSSES THE
REGION. BREEZY CONDITIONS POSSIBLE THURSDAY NIGHT AND FRIDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
109 PM EST MON DEC 17 2012
.SYNOPSIS...
AN APPROACHING COLD FRONT WILL MOVE THROUGH THE FORECAST AREA
TONIGHT. SHOWERS AND POSSIBLY A FEW THUNDERSTORMS WILL OCCUR
AHEAD OF THE FRONT. DRY HIGH PRESSURE BEHIND THE FRONT WILL
DOMINATE TUESDAY AND WEDNESDAY. ANOTHER COLD FRONT WILL MOVE INTO
THE AREA THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SHOWERS HAVE OVERSPREAD THE FORECAST AREA ASSOCIATED WITH THE H85
JET. SURFACE-BASED INSTABILITY WAS CONFINED TO SOUTH GEORGIA
WHERE EARLY AFTERNOON LI VALUES WERE NEAR -2. THE NAM FORECAST OF
LI/S LOWERING TO NEAR -4 IN THE FORECAST AREA DURING THE AFTERNOON
APPEARS OVERDONE. INSTABILITY SHOULD REMAIN LIMITED BECAUSE OF
CLOUDINESS AND WIDESPREAD RAIN. THE RAP APPEARS MORE REASONABLE
WITH POSITIVE LI/S THROUGH THE AFTERNOON WITH GREATER INSTABILITY
THIS EVENING AFTER THE MOISTURE BECOMES SHALLOW AND MORE COOLING
ALOFT OCCURS AS THE UPPER TROUGH MOVES INTO THE AREA. SEVERE
THUNDERSTORMS ARE NOT OUT OF THE QUESTION BECAUSE OF HIGH SHEAR
BUT WE BELIEVE THE CHANCE IS LOW BECAUSE OF A LACK OF SURFACE-
BASED INSTABILITY. SHOWERS SHOULD END FROM WEST TO EAST AS THE
DEEPER MOISTURE AND H85 JET AHEAD OF THE FRONT SHIFTS EAST OF THE
AREA. MIXING ASSOCIATED WITH THE FRONT SHOULD HELP HOLD UP
TEMPERATURES TONIGHT. WE USED THE WARMER TEMPERATURE GUIDANCE.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
DRY HIGH PRESSURE BEHIND THE COLD FRONT WILL DOMINATE TUESDAY
THROUGH WEDNESDAY NIGHT. STRONG RADIATIONAL COOLING WILL OCCUR
TUESDAY NIGHT. THE TEMPERATURE GUIDANCE WAS CLOSE THROUGH THE
PERIOD.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
THE GFS AND ECMWF SHOW A COLD FRONT IN THE FORECAST AREA THURSDAY
OR THURSDAY NIGHT. THE MODELS SHOW STRONG SHEAR ASSOCIATED WITH
THIS FRONT WITH H85 WINDS NEAR 60 KNOTS. THUNDERSTORMS WITH
DAMAGING WIND COULD POSSIBLY OCCUR ALTHOUGH INSTABILITY SHOULD BE
A LIMITING FACTOR. DRY HIGH PRESSURE BEHIND THIS FRONT SHOULD
DOMINATE DURING THE REST OF THE MEDIUM-RANGE PERIOD.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
HIGHLY VARIABLE CONDITIONS CONTINUE ACROSS THE TAF SITES...WITH MVFR
AND IFR EXPECTED TO DOMINATE THE PERIOD.
COLD FRONT MAKING SLOW PROGRESS ACROSS THE WESTERN GULF REGION. AN
AREA OF SHOWER ALONG WITH SOME THUNDERSTORMS ACROSS EXTREME SRN GA
AND THE PANHANDLE OF FL WILL CONTINUE TO MOVE NORTHEAST THROUGHOUT
THE AFTERNOON. SATELLITE IMAGERY SHOWS PLENTY OF CLOUDS ACROSS THE
AREA AND PLENTY MORE UPSTREAM...SO EXPECT CLOUDY CONDITIONS FOR MUCH
OF THE TAF PERIOD. HAVE CONTINUED WITH RAIN IN THE FORECAST THROUGH
THE AFTERNOON...HOWEVER HAVE NOT INCLUDED THUNDER AS CONFIDENCE IS
LOW AT THIS TIME FOR OCCURRENCE AT ANY TAF SITES. THE BEST CHANCE
FOR THUNDER WOULD BE THE SOUTHERN/EASTERN TAFS CLOSER TO THE MORE
UNSTABLE CONDITIONS...AGS/DNL/OGB. THE RAIN WILL BEGIN TO DIMINISH
ACROSS THE AREA THIS EVENING INTO TONIGHT...HOWEVER WITH PLENTY OF
MOISTURE AND 30 TO 40 KT LOW LEVEL JET EXPECT LOW CLOUDS AND FOG TO
LINGER LATE INTO THE PERIOD. ON TUESDAY...EXPECT CLEARING TO BEGIN
RATHER QUICKLY AS TIGHT SURFACE PRESSURE GRADIENT BETWEEN DEPARTING
FRONT AND HIGH BUILDING IN FROM THE WEST WILL PRODUCE BREEZY
CONDITIONS BEGINNING AROUND 15Z.
EXTENDED AVIATION OUTLOOK...RESTRICTIONS AGAIN POSSIBLE THURSDAY
MORNING INTO FRIDAY MORNING AS ANOTHER COLD FRONT CROSSES THE
REGION. BREEZY CONDITIONS POSSIBLE THURSDAY NIGHT AND FRIDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
1231 PM EST MON DEC 17 2012
.PREV DISCUSSION... /ISSUED 654 AM EST MON DEC 17 2012/
SHORT TERM /TODAY THROUGH TUESDAY/...
MAIN FCST CONCERN REMAINS CHC FOR SVR CONVECTION TODAY. 00Z MODEL
RUNS NOT SHOWING MUCH CHANGE FROM PREVIOUS RUNS...BEST TIMING FOR
VERTICAL WIND SHEAR AND INSTABILITY WILL BE 15Z-21Z. PROBLEM IS
THAT WE SAW NORTH WINDS MUCH OF THE DAY AND EVENING SUNDAY...IN
RESPONSE TO LOW FROM LARGE PERSISTENT PRECIP AREA...WHICH
MINIMIZED NORTHWARD MOISTURE TRANSPORT. LATEST RAP ANALYSIS ALSO
SHOWING THAT MUCAPE REMAINS NEAR ZERO IN THE REGION EXCEPT ALONG
THE GULF COAST. USUALLY SEE ELEVATED INSTABILITY SURGING NORTHEAST
AT THIS TIME OF NIGHT PRECEDING FRONT AND STORMS. 06Z NAM STARTING
TO AGREE WITH LATEST ANALYSIS IN THE NEAR TERM BUT STILL APPEARS A
LITTLE TOO QUICK BRINGING HIGHER THETA-E AIR AND HIGHER CAPE NORTH
BY 15Z. ASSUMING MODELS ON TRACK WITH INSTABILITY...SHOULD SEE SVR
THREAT DEVELOP AFTER 15Z. DO NOT SEE ANY THREAT OF HAIL GREATER
THAN ONE INCH. DAMAGING WINDS AND AN ISOLATED TORNADO THREAT
REMAIN POSSIBLE BUT CONTINGENT ON MOISTURE TRANSPORT AND
INSTABILITY DEVELOPING AS FCST. WILL HAVE TO WATCH REAL TIME
ANALYSIS CLOSELY THIS MORNING.
PRECIP WILL MOVE OUT QUICKLY TONIGHT. NO ISSUES WITH FCST BEYOND
THIS. DRY AIR SHOULD FILTER IN SLOWLY BUT ENOUGH TO PRECLUDE
DEVELOPMENT OF FOG. USED MAV/MET/ECMWF MOS BLEND FOR TEMPS.
SNELSON
LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
MAIN FORECAST CONCERN IN THE EXTENDED PERIODS IS THE FAIRLY STRONG
COLD FRONT EXPECTED ON THURSDAY. WEAK RIDGING OVER THE SOUTHEAST
AT THE BEGINNING OF THE EXTENDED PERIODS...WITH NEARLY NEARLY
ZONAL UPPER LEVEL FLOW...SFC HIGH AND DRY CONDITIONS ON WEDNESDAY.
ALTHOUGH THERE ARE SOME DISCREPANCIES EXTENDED MODELS ARE IN GOOD
AGREEMENT WITH GENERAL PATTERN MIDWEEK. AN UPPER LEVEL SHORT WAVE
CROSSES THE ROCKIES ON WEDNESDAY LIFTING INTO THE OHIO VALLEY BY
THURSDAY AFTERNOON. GFS IS DEEPER AND CUTS OFF THE LOW BY THURSDAY
AFTERNOON...ECMWF IS SLOWER TO CUT OFF LOW BUT BY THURSDAY NIGHT
BOTH MODELS ARE SIMILAR IN LOCATION AND STRENGTH OF LOW. WITH WEAK
RIDGING AND SURFACE HIGH SHIFTING EAST ON WEDNESDAY MODELS ARE IN
AGREEMENT THAT BEST MOISTURE RETURNS THURSDAY MORNING AHEAD OF THE
COLD FRONT WHICH MOVES ACROSS THE FORECAST AREA RATHER QUICKLY BY
THURSDAY EVENING. INSTABILITY IS LIMITED HOWEVER BOTH GFS AND
ECMWF AREA SHOWING GOOD SHEAR...AND GIVEN THE STRENGTH OF THE FRONT
WILL CONTINUE ISOLATED THUNDERSTORMS DURING THE DAY. RAINFALL
RATES WILL BE HALF INCH OR LESS BASED UPON THE SPEED OF THE STORM.
ZONAL FLOW ALOFT AND SURFACE HIGH PRESSURE BUILD BACK IN FOR THE
WEEKEND. GFS SHOWING SOME MOISTURE RETURN SATURDAY BUT MAINLY
EXPECT AN INCREASE IN CLOUDS ACROSS THE FORECAST AREA SATURDAY AND
SUNDAY. GUIDANCE TEMPERATURES ARE PRETTY CLOSE AND WILL TAKE A
BLEND OF MAV/ECMWF MOS THROUGH THE EXTENDED PERIODS.
ATWELL
&&
.AVIATION...
18Z UPDATE...
IFR CEILINGS THE MAIN CONCERN FOR MOST TAF SITES EVENTUALLY
DEVELOPING OVER MCN. MAIN VSBY RESTRICTIONS ASSOCIATED WITH THE
RAIN AREA WITH BEST THUNDERSTORMS CHANCES ABOUT MCN S THIS AFTERNOON.
PRECIP DIMINISHES THIS AFTERNOON AND EVENING. UNSURE HOW MUCH FOG
THERE COULD BE OVERNIGHT. SURFACE WINDS SSW BECOMING W 5-10 KTS.
//ATL CONFIDENCE...18Z UPDATE...
HIGH CONFIDENCE FOR IFR CIGS...WEATHER AND WINDS INTO THE OVERNIGHT.
LOW TO MEDIUM CONFIDENCE FOR VSBYS.
BDL
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 58 47 62 36 / 70 20 0 0
ATLANTA 59 47 61 41 / 50 20 0 0
BLAIRSVILLE 54 41 56 29 / 50 40 0 0
CARTERSVILLE 61 42 59 32 / 30 20 0 0
COLUMBUS 63 50 65 40 / 90 10 0 0
GAINESVILLE 57 45 60 39 / 50 20 0 0
MACON 62 49 66 35 / 100 20 0 0
ROME 61 41 60 33 / 40 20 0 0
PEACHTREE CITY 60 42 62 32 / 60 20 0 0
VIDALIA 73 56 69 42 / 90 20 0 0
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...BDL
LONG TERM....DEESE
AVIATION...BDL
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
158 PM CST MON DEC 17 2012
.DISCUSSION...
1215 PM CST
SOME SMALL CHANGES MADE TO THE AFTERNOON FORECAST...MAINLY TO
INHIBIT TEMPS A FEW DEGREES AND TO INCLUDE THE MENTION OF SNOW IN
THE SOUTHEAST FORECAST AREA. WELL-DEFINED UPPER WAVE IS MOVING ENE
OVER THE LOWER OHIO VALLEY EARLY THIS AFTERNOON. A FAIRLY
IMPRESSIVE UPPER LEVEL TEMPERATURE GRADIENT EXISTS ON THE NORTH
AND NORTHWEST SIDE OF THIS SYSTEM...AND WITH THE SYSTEM ITSELF
STILL INTENSIFYING...THIS AREA IS FAVORED FOR FRONTOGENESIS AND
POTENTIALLY ENHANCED PRECIP ENOUGH TO OVERCOME A DRY PART OF THE
COLUMN. SURE ENOUGH...RADAR ECHOES HAVE BEEN INCREASING ACROSS
CENTRAL IL AND THE SOUTHEAST FORECAST AREA. WITH MARGINAL WET BULB
TEMPERATURES...A POTENTIAL FOR WET BIG-FLAKED SNOW EXISTS. THIS
HAS ALREADY BEEN OBSERVED IN LINCOLN /AAA/. BOTH THE RAP AND NAM
INDICATE OMEGA WITHIN THE DENDRITIC GROWTH AREA LIKELY AIDING IN
LARGER FLAKES THAT ARE LESS SUSCEPTIBLE TO MELT/SUBLIMATE ON THEIR
WAY DOWNWARD. THESE MODELS INDICATE THIS FORCING NEAR -15C TO
CONTINUE THROUGH MID-AFTERNOON...WHICH MAKES SENSE ON THE SYNOPTIC
SCALE WITH THE PATH AND EVOLUTION OF THE SYSTEM. A DUSTING COULD
HAPPEN BUT OVERALL NO REAL ACCUMULATION EXPECTED.
EARLY LOOK AT 12Z GUIDANCE FOR THE UPCOMING SNOW EVENT INDICATES
NO DRAMATIC SHIFTS...HOWEVER PLENTY OF INTERESTING FEATURES ARE
EVIDENT. THE NAM/GFS/SREF CONTINUE TO FAVOR A MORE NORTHWARD TRACK
OF THE PANHANDLE HOOK...WITH THE EC AND GEM SOUTH. THIS RESULTS
IN DRASTIC DIFFERENCES IN THERMAL PROFILES AND SNOWFALL DURATION
AND THUS ACCUMULATION ACROSS A LARGE PART OF THE AREA. MOST OF THE
GUIDANCE AGREES ON IMPRESSIVELY STRONG WINDS CORRELATING WITH THE
COLUMN COOLING ON THU AFTERNOON AND EVE. THE GENERAL IDEA REMAINS
STRONG TO HAVE SOME RAIN INDICATED WEDNESDAY NIGHT INTO THURSDAY
MORNING IN THE FORECAST AND THEN TRENDING MORE TOWARD SNOW AND
BLOWING SNOW.
MTF/RC
//PREV DISCUSSION...
337 AM CST
FORECAST CONCERNS FOCUS MAINLY ON A COUPLE OF CHANCES FOR SOME LIGHT
PRECIPITATION ACROSS PORTIONS OF THE CWA LATER TODAY/THIS EVENING
AND AGAIN TUESDAY...WITH ATTENTION THEN QUICKLY TURNING TO THE
POTENTIAL FOR A STRONG WINTER STORM FOR THE UPPER MIDWEST WEDNESDAY
NIGHT THROUGH THURSDAY.
SURFACE LOW PRESSURE ACROSS THE NORTHERN GREAT LAKES REGION
CONTINUES TO DRIFT SLOWLY AWAY TO THE NORTHEAST EARLY THIS MORNING.
COLD FRONT WHICH PUSHED ACROSS THE AREA SUNDAY HAS EDGED SOUTHEAST
TO THE OHIO RIVER VALLEY...WHILE WEAK HIGH PRESSURE HAS SPREAD INTO
ILLINOIS FROM THE WEST. LOOKING ALOFT...BROAD TROUGHING LINGERS
ACROSS THE CENTRAL CONUS TO THE SOUTH OF A CLOSED UPPER LOW OVER
WESTERN ONTARIO. SLOW PROGRESSION OF FEATURES AND PRESENCE OF
SEVERAL SMALLER AMPLITUDE MID-LEVEL SHORT WAVES HAVE PREVENTED
STRONG DRYING/SUBSIDENCE AND CLEARING OF LOW CLOUDS ACROSS THE
REGION. GOES WATER VAPOR IMAGERY DEPICTS A COUPLE OF SUCH MID-LEVEL
SHORT WAVES UPSTREAM OF THE REGION TODAY...ONE LIFTING OUT OF THE
RED RIVER VALLEY OF THE SOUTH TOWARD THE LOWER OHIO VALLEY...AND
ANOTHER ACROSS THE CENTRAL PLAINS OF NEBRASKA/KANSAS. NEAR-TERM
GUIDANCE ARE IN AGREEMENT IN BRINGING THESE FEATURES EAST ACROSS THE
MID/UPPER MISSISSIPPI AND OHIO VALLEYS THROUGH THIS EVENING. MAIN
FOCUS FOR MEASURABLE PRECIPITATION SHOULD REMAIN LARGELY WITH WEAK
SURFACE LOW REFLECTION WHICH PROPAGATES ALONG THE AFOREMENTIONED LOW
LEVEL BAROCLINIC ZONE ALONG THE OHIO RIVER...THOUGH VARIOUS GUIDANCE
INCLUDING THE GFS/ECMWF/SREF AND GEM ALL INDICATE A LITTLE LIGHT QPF
STREAK FROM SOUTHEAST KS ACROSS CENTRAL MO AND INTO CENTRAL IL WHICH
INCLUDES OUR FAR SOUTHERN COUNTIES IN ASSOCIATION WITH THE CENTRAL
PLAINS VORT AND POCKET OF MID-LEVEL MOISTURE. ALREADY SEEING SOME
LIGHT RADAR RETURNS ACROSS SOUTHERN KS AT THIS HOUR...WHICH GUIDANCE
SUGGESTS WOULD AFFECT PARTS OF THE WFO LOT CWA ROUGHLY SOUTH OF A
PONTIAC-VALPARAISO LINE THIS AFTERNOON AND EARLY EVENING. LOW LEVEL
THERMAL/MOISTURE PROFILES SUGGEST THIS WOULD MAINLY BE LIGHT
RAIN/SPRINKLES...WITH PRECIP EXPECTED TO END THIS EVENING BEFORE LOW
LEVEL THICKNESS DECREASES ENOUGH FOR MIXED PRECIP.
STRONG UPPER JET STREAK NOTED IN 00Z RAOB ANALYSIS CURRENTLY PUSHING
ACROSS THE OREGON COAST IS PROJECTED TO SPREAD ACROSS THE CENTRAL
CONUS TONIGHT...INDUCING LOW PRESSURE DEVELOPMENT ACROSS THE
NORTHERN PLAINS/UPPER MIDWEST. GUIDANCE DEPICTS WEAK SURFACE LOW
PRESSURE MOVING ALONG THE IL/WI BORDER AREA TUESDAY AFTERNOON...
WITH REGION OF WARM ADVECTION AND RESULTANT ASCENT FOCUSED ACROSS
SOUTHERN WI/FAR NORTHERN IL. ISENTROPIC PROGS IN 290-295 K LAYER
INDICATE A PERIOD OF SATURATION AND FAIRLY GOOD CONVERGENCE ACROSS
THE NORTHERN PARTS OF THE CWA TUESDAY MORNING...WITH SEVERAL
GUIDANCE SETS PRODUCING A LITTLE LIGHT QPF. WHILE NOT EXPECTED TO
AMOUNT TO MUCH...THERMAL PROFILES EARLY TUESDAY DO INDICATE THE
POTENTIAL FOR A LITTLE LIGHT SNOW TO MIX/CHANGE TO LIGHT RAIN DURING
THE MORNING HOURS...BEFORE LARGELY SHIFTING NORTHEAST ACROSS WI/LAKE
MICHIGAN. HAVE ONLY CARRIED SLIGHT CHANCE POPS FOR LIGHT PRECIP OVER
NORTHERN IL...WITH A LITTLE BETTER CHANCE RIGHT ALONG THE WISCONSIN
BORDER.
MEDIUM RANGE GUIDANCE REMAINS REMARKABLY SIMILAR IN AMPLIFYING UPPER
FLOW ACROSS THE CONUS TUESDAY NIGHT INTO WEDNESDAY...AS SYSTEM
CURRENTLY SEEN NEAR 150W 40N IN NORTHERN HEMISPHERIC WATER VAPOR
IMAGERY AMPLIFIES ALONG THE WEST COAST AND INDUCES BROAD DOWNSTREAM
RIDGE ACROSS OUR REGION. GUIDANCE MAINTAINS TREND OF UPPER TROUGH
DIGGING ACROSS THE FOUR CORNERS REGION BY 12Z WEDNESDAY...WITH
SURFACE CYCLOGENESIS OCCURRING OVER THE TX/OK PANHANDLE REGION.
UPPER TROUGH THEN ADVANCES ACROSS THE PLAINS...BECOMING NEGATIVELY
TILTED ACROSS THE MIDWEST AND EVENTUALLY CLOSING OFF THE MID-LEVEL
CIRCULATION OVER THE WESTERN GREAT LAKES ON THURSDAY. THE ASSOCIATED
SURFACE LOW MEANWHILE...DEEPENS AS IT TREKS NORTHEAST ACROSS
MISSOURI AND ILLINOIS LATE WEDNESDAY NIGHT/THURSDAY MORNING AND INTO
LOWER MICHIGAN BY THURSDAY EVENING. WHILE MODEL SOLUTIONS HAVE BEEN
FAIRLY STEADY IN THEIR DEPICTION OF THE OVERALL SCENARIO FOR THE
PAST FEW DAYS OF MODEL RUNS...SOME DETAIL DIFFERENCES DO REMAIN WITH
RESPECT TO THE TRACK OF THE SURFACE LOW. 00Z GEFS ENSEMBLE
CLUSTERING HAS TIGHTENED UP FROM ITS 12Z RUN YESTERDAY...WITH A
MEDIAN SOLUTION TRACK JUST SOUTHEAST OF CHICAGO. THE NAM/SREF ARE
THE FARTHEST WEST...ACTUALLY TAKING THE LOW ACROSS FAR NORTHWEST IL.
THE 00Z GEM FOLLOWS A SIMILAR TRACK...THOUGH IS SLOWER BY A GOOD 6+
HOURS. THE 00Z ECMWF IS SIMILAR IN SPEED/TIMING TO THE GEM...THOUGH
TRACKS FARTHER TO THE RIGHT ALONG A DANVILLE-GOSHEN LINE...OR ABOUT
50 MILES WEST OF THE 12Z ECMWF TRACK. OFTEN...DEEPENING NEGATIVELY
TILTED STORM SYSTEMS EMERGING FROM THE SOUTHWEST TEND TO BE
DEEPER...SLOWER AND TRACK FARTHER TO THE WEST/NORTHWEST THAN MODELS
INITIALLY FORECAST...SO PERHAPS IT IS NOT TOO SURPRISING TO SEE THE
ECMWF TREND BACK NORTHWEST JUST A BIT. AT THIS POINT...HAVE BASED
FORECAST ALONG THE LINES OF A 00Z GEM/00Z ECMWF BLEND ALLOWING FOR
THE SLOWER TIMING OF THESE TWO SOLUTIONS...WITH A LOW TRACK THAT AT
LEAST INITIALLY WRAPS WARMER AIR AND RAIN INTO THE EASTERN HALF OF
THE CWA. THUS HAVE MAINTAINED A PROGRESSION OF RAIN/SNOW
NORTHWEST...RAIN EAST...EVENTUALLY CHANGING TO ALL SNOW AS THE LOW
PASSES THURSDAY AND COLD AIR WRAPS INTO THE DEPARTING LOW. WILL
CONTINUE TO HIGHLIGHT THE POTENTIAL FOR A SIGNIFICANT STORM ACROSS
THE REGION IN THE HWO...THOUGH STILL A BIT EARLY TO NAIL DOWN WHERE
SPECIFIC SNOW AMOUNTS WOULD FALL EXCEPT THE CONCEPT OF MORE ACROSS
THE NORTHWEST PART OF THE CWA AND SIGNIFICANTLY LESS IN THE
SOUTHEAST. IN ADDITION TO THE POTENTIAL FOR SNOW...VERY WINDY
CONDITIONS ARE ANTICIPATED BY THURSDAY NIGHT...AS THE DEEPENING LOW
MOVES INTO LOWER MICHIGAN...WITH NORTHWEST WINDS POTENTIALLY GUSTING
INTO THE 45 MPH RANGE.
A BRIEF PERIOD OF COLDER BUT QUIET WEATHER MOVES INTO THE AREA
FRIDAY THROUGH THE WEEKEND...WITH SOME LINGERING SNOW SHOWERS
DOWNWIND OF LAKE MICHIGAN INTO INDIANA/MICHIGAN.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* HOW LATE INTO NIGHT MVFR CEILINGS WILL HOLD ON BEFORE
CLEARING...OR POSSIBLY NOT CLEARING AND PERSISTING THROUGH THE
NIGHT.
TRS
//DISCUSSION...UPDATED 18Z...
WIDESPREAD MVFR STRATUS ACROSS THE REGION WITH CEILINGS DOWN TO
IFR WELL OFF TO THE W THROUGH NW ACROSS IA...MN AND SE WI. VERY
WEEK PRESSURE GRADIENT ACROSS THE REGION SO LOW LEVEL FLOW IS IF
NOT NIL THEN VERY LIGHT. AS THE AFTERNOON PROGRESSES AND THROUGH
THE EVENING A WEAK RIDGE OF HIGH PRESSURE WILL BUILD SE FROM MN
AND WI TO OVER THE LOCAL AREA. WINDS SHOULD GENERALLY FAVOR A NW
TO N DIRECTION BUT REMAIN IN THE 3 TO 6 KT RANGE AND THEN BECOME
LIGHT AND VARIABLE OR CALM AGAIN AS THE RIDGE AXIS SETTLES OVER
THE LOCAL TERMINALS TONIGHT.
BY 12Z TUE LOW PRESSURE IS TO HAVE MOVED E FROM THE CENTRAL
PLAINS TO AROUND THE WESTERN IA AREA. IN RESPONSE WINDS BY
DAYBREAK SHOULD HAVE TURNED TO OUT SSE AS THE LOW CONTINUES TO
APPROACH THE AREA FROM THE W.
THERE IS A SLIGHT CHANCE OF SOME VERY LIGHT PRECIPITATION DURING
THU ACROSS NORTHERN IL THOUGH MODELS INDICATING SIGNIFICANT
SATURATION PRESSURE DEFICITS PERSIST WHILE BEST ISENTROPIC
UPGLIDE/OMEGA MOVE OVER THE AREA DURING THE MORNING LEAVING
BETTER CHANCE OF LIGHT SNOWFALL ACROSS SOUTHERN MN AND CENTRAL
WI.
MODEL THERMAL PROFILES AND MOS GUIDANCE ALL SUGGESTING THAT THE
LOW LEVEL INVERSION WILL WEAKEN AND THE STRATUS CLOUDS WILL
DISSIPATE DURING THE NIGHT WHILE MID LEVEL CLOUDS SPREAD OVER THE
AREA AHEAD OF A SHORT WAVE CURRENTLY OVER ID MOVES E TO THE
PLAINS OVERNIGHT.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN NIL/LIGHT AND VARIABLE WINDS REST OF
AFTERNOON AND TONIGHT.
* HIGH CONFIDENCE CEILINGS WILL REMAIN AOA 015 THRESHOLD REST OF
DAY AND FIRST PART OF EVENING.
* MODERATE CONFIDENCE STRATUS DECK WILL DISSIPATE BUT CONFIDENCE
IN TIMING OF ITS OCCURRENCE DURING THE OVERNIGHT IS LOW.
* HIGH CONFIDENCE THAT NO SIGNIFICANT PRECIPITATION WILL FALL OVER
THE LOCAL AREA TUE A.M.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
* TUESDAY NIGHT AND WEDNESDAY...VFR.
* WEDNESDAY NIGHT...RAIN DEVELOPING. IFR POSSIBLE.
* THURSDAY...RAIN CHANGING TO SNOW. IFR/LIFR LIKELY. BECOMING
VERY WINDY WITH GUSTS 35+ KTS BY EVENING.
* THURSDAY NIGHT...VERY WINDY WITH GUSTS 35+ KT. SNOW ENDING.
BLOWING SNOW. LIFR IMPROVING TO MVFR.
* FRIDAY...GUSTY NORTHWEST WINDS. VFR.
* SATURDAY AND SUNDAY...VFR.
&&
.MARINE...
312 AM...NORTHWEST STORM FORCE WINDS TO 50 KT NOW EXPECTED BY
LATE THURSDAY AFTERNOON AND CONTINUING INTO THURSDAY NIGHT.
MAIN FORECAST CONCERN/CHALLENGE REMAINS THE POWERFUL WINTER STORM
EXPECTED TO MOVE ACROSS THE GREAT LAKES REGION THURSDAY/THURSDAY
NIGHT. THERE REMAINS UNCERTAINTY REGARDING THE EXACT TRACK OF THE
LOW FROM THE VARIOUS FORECAST MODELS THOUGH THERE IS SOME
CONSENSUS THAT THIS STORM WILL TRACK VERY CLOSE TO OR PERHAPS OVER
SOUTHERN LAKE MICHIGAN. THE STORM WILL BE IN THE PROCESS OF
RAPIDLY DEEPENING DURING THIS TIME. IF THIS STORM DOES INDEED
FOLLOW THIS TRACK...WINDS WILL RAPIDLY INCREASE THURSDAY
AFTERNOON AND CONTINUE INTO THURSDAY NIGHT WITH FORECAST SOUNDINGS
SHOWING GUSTS INTO THE 45-50KT RANGE WHICH COULD BE TOO LOW THOUGH
STRONGEST WINDS PROBABLY WOULD ONLY LAST 4-8 HOURS THOUGH GALES
SHOULD PERSIST WELL INTO FRIDAY AS THEY SLOWLY RELAX INTO FRIDAY
EVENING.
IN THE SHORTER TERM...LOW PRESSURE OVER THE NORTHERN LAKES WILL
LIFT NORTH TODAY AND WEAKEN...THIS WILL MAINTAIN A MODEST WESTERLY
GRADIENT OVER THE NORTHERN HALF OF THE LAKE THIS MORNING. WINDS
WILL TURN NORTHERLY OVER THE SOUTH END OF THE LAKE AHEAD OF A WEAK
RIDGE OF HIGH PRESSURE WHICH WILL MOVE ACROSS THE WESTERN LAKES
OVERNIGHT. ANOTHER LOW WILL BE MOVING NORTHEAST ACROSS THE OHIO
VALLEY THIS AFTERNOON AND DEEPENING AS IT MOVES TOWARD NEW ENGLAND
ON TUESDAY. SO HOW STRONG THE NORTHERLY GRADIENT BECOMES ON THE
SOUTH END OF THE LAKE LATER TODAY WILL NEED TO BE MONITORED.
ANOTHER FAST MOVING LOW WILL MOVE ACROSS THE IL/WI REGION ON
TUESDAY AND THEN ACROSS SOUTHERN LAKE MICHIGAN TUESDAY EVENING.
THE GRADIENT MAY INCREASE ENOUGH TO SUPPORT 15-25 KT ON THE FAR
SOUTH END OF THE LAKE AHEAD OF THE LOW AND AGAIN FROM THE WEST
TUESDAY EVENING AS THE LOW PASSES. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS CHICAGO/ROMEOVILLE IL
1230 PM CST MON DEC 17 2012
.DISCUSSION...
1215 PM CST
SOME SMALL CHANGES MADE TO THE AFTERNOON FORECAST...MAINLY TO
INHIBIT TEMPS A FEW DEGREES AND TO INCLUDE THE MENTION OF SNOW IN
THE SOUTHEAST FORECAST AREA. WELL-DEFINED UPPER WAVE IS MOVING ENE
OVER THE LOWER OHIO VALLEY EARLY THIS AFTERNOON. A FAIRLY
IMPRESSIVE UPPER LEVEL TEMPERATURE GRADIENT EXISTS ON THE NORTH
AND NORTHWEST SIDE OF THIS SYSTEM...AND WITH THE SYSTEM ITSELF
STILL INTENSIFYING...THIS AREA IS FAVORED FOR FRONTOGENESIS AND
POTENTIALLY ENHANCED PRECIP ENOUGH TO OVERCOME A DRY PART OF THE
COLUMN. SURE ENOUGH...RADAR ECHOES HAVE BEEN INCREASING ACROSS
CENTRAL IL AND THE SOUTHEAST FORECAST AREA. WITH MARGINAL WET BULB
TEMPERATURES...A POTENTIAL FOR WET BIG-FLAKED SNOW EXISTS. THIS
HAS ALREADY BEEN OBSERVED IN LINCOLN /AAA/. BOTH THE RAP AND NAM
INDICATE OMEGA WITHIN THE DENDRITIC GROWTH AREA LIKELY AIDING IN
LARGER FLAKES THAT ARE LESS SUSCEPTIBLE TO MELT/SUBLIMATE ON THEIR
WAY DOWNWARD. THESE MODELS INDICATE THIS FORCING NEAR -15C TO
CONTINUE THROUGH MID-AFTERNOON...WHICH MAKES SENSE ON THE SYNOPTIC
SCALE WITH THE PATH AND EVOLUTION OF THE SYSTEM. A DUSTING COULD
HAPPEN BUT OVERALL NO REAL ACCUMULATION EXPECTED.
EARLY LOOK AT 12Z GUIDANCE FOR THE UPCOMING SNOW EVENT INDICATES
NO DRAMATIC SHIFTS...HOWEVER PLENTY OF INTERESTING FEATURES ARE
EVIDENT. THE NAM/GFS/SREF CONTINUE TO FAVOR A MORE NORTHWARD TRACK
OF THE PANHANDLE HOOK...WITH THE EC AND GEM SOUTH. THIS RESULTS
IN DRASTIC DIFFERENCES IN THERMAL PROFILES AND SNOWFALL DURATION
AND THUS ACCUMULATION ACROSS A LARGE PART OF THE AREA. MOST OF THE
GUIDANCE AGREES ON IMPRESSIVELY STRONG WINDS CORRELATING WITH THE
COLUMN COOLING ON THU AFTERNOON AND EVE. THE GENERAL IDEA REMAINS
STRONG TO HAVE SOME RAIN INDICATED WEDNESDAY NIGHT INTO THURSDAY
MORNING IN THE FORECAST AND THEN TRENDING MORE TOWARD SNOW AND
BLOWING SNOW.
MTF/RC
&&
.PREV DISCUSSION...
337 AM CST
FORECAST CONCERNS FOCUS MAINLY ON A COUPLE OF CHANCES FOR SOME LIGHT
PRECIPITATION ACROSS PORTIONS OF THE CWA LATER TODAY/THIS EVENING
AND AGAIN TUESDAY...WITH ATTENTION THEN QUICKLY TURNING TO THE
POTENTIAL FOR A STRONG WINTER STORM FOR THE UPPER MIDWEST WEDNESDAY
NIGHT THROUGH THURSDAY.
SURFACE LOW PRESSURE ACROSS THE NORTHERN GREAT LAKES REGION
CONTINUES TO DRIFT SLOWLY AWAY TO THE NORTHEAST EARLY THIS MORNING.
COLD FRONT WHICH PUSHED ACROSS THE AREA SUNDAY HAS EDGED SOUTHEAST
TO THE OHIO RIVER VALLEY...WHILE WEAK HIGH PRESSURE HAS SPREAD INTO
ILLINOIS FROM THE WEST. LOOKING ALOFT...BROAD TROUGHING LINGERS
ACROSS THE CENTRAL CONUS TO THE SOUTH OF A CLOSED UPPER LOW OVER
WESTERN ONTARIO. SLOW PROGRESSION OF FEATURES AND PRESENCE OF
SEVERAL SMALLER AMPLITUDE MID-LEVEL SHORT WAVES HAVE PREVENTED
STRONG DRYING/SUBSIDENCE AND CLEARING OF LOW CLOUDS ACROSS THE
REGION. GOES WATER VAPOR IMAGERY DEPICTS A COUPLE OF SUCH MID-LEVEL
SHORT WAVES UPSTREAM OF THE REGION TODAY...ONE LIFTING OUT OF THE
RED RIVER VALLEY OF THE SOUTH TOWARD THE LOWER OHIO VALLEY...AND
ANOTHER ACROSS THE CENTRAL PLAINS OF NEBRASKA/KANSAS. NEAR-TERM
GUIDANCE ARE IN AGREEMENT IN BRINGING THESE FEATURES EAST ACROSS THE
MID/UPPER MISSISSIPPI AND OHIO VALLEYS THROUGH THIS EVENING. MAIN
FOCUS FOR MEASURABLE PRECIPITATION SHOULD REMAIN LARGELY WITH WEAK
SURFACE LOW REFLECTION WHICH PROPAGATES ALONG THE AFOREMENTIONED LOW
LEVEL BAROCLINIC ZONE ALONG THE OHIO RIVER...THOUGH VARIOUS GUIDANCE
INCLUDING THE GFS/ECMWF/SREF AND GEM ALL INDICATE A LITTLE LIGHT QPF
STREAK FROM SOUTHEAST KS ACROSS CENTRAL MO AND INTO CENTRAL IL WHICH
INCLUDES OUR FAR SOUTHERN COUNTIES IN ASSOCIATION WITH THE CENTRAL
PLAINS VORT AND POCKET OF MID-LEVEL MOISTURE. ALREADY SEEING SOME
LIGHT RADAR RETURNS ACROSS SOUTHERN KS AT THIS HOUR...WHICH GUIDANCE
SUGGESTS WOULD AFFECT PARTS OF THE WFO LOT CWA ROUGHLY SOUTH OF A
PONTIAC-VALPARAISO LINE THIS AFTERNOON AND EARLY EVENING. LOW LEVEL
THERMAL/MOISTURE PROFILES SUGGEST THIS WOULD MAINLY BE LIGHT
RAIN/SPRINKLES...WITH PRECIP EXPECTED TO END THIS EVENING BEFORE LOW
LEVEL THICKNESS DECREASES ENOUGH FOR MIXED PRECIP.
STRONG UPPER JET STREAK NOTED IN 00Z RAOB ANALYSIS CURRENTLY PUSHING
ACROSS THE OREGON COAST IS PROJECTED TO SPREAD ACROSS THE CENTRAL
CONUS TONIGHT...INDUCING LOW PRESSURE DEVELOPMENT ACROSS THE
NORTHERN PLAINS/UPPER MIDWEST. GUIDANCE DEPICTS WEAK SURFACE LOW
PRESSURE MOVING ALONG THE IL/WI BORDER AREA TUESDAY AFTERNOON...
WITH REGION OF WARM ADVECTION AND RESULTANT ASCENT FOCUSED ACROSS
SOUTHERN WI/FAR NORTHERN IL. ISENTROPIC PROGS IN 290-295 K LAYER
INDICATE A PERIOD OF SATURATION AND FAIRLY GOOD CONVERGENCE ACROSS
THE NORTHERN PARTS OF THE CWA TUESDAY MORNING...WITH SEVERAL
GUIDANCE SETS PRODUCING A LITTLE LIGHT QPF. WHILE NOT EXPECTED TO
AMOUNT TO MUCH...THERMAL PROFILES EARLY TUESDAY DO INDICATE THE
POTENTIAL FOR A LITTLE LIGHT SNOW TO MIX/CHANGE TO LIGHT RAIN DURING
THE MORNING HOURS...BEFORE LARGELY SHIFTING NORTHEAST ACROSS WI/LAKE
MICHIGAN. HAVE ONLY CARRIED SLIGHT CHANCE POPS FOR LIGHT PRECIP OVER
NORTHERN IL...WITH A LITTLE BETTER CHANCE RIGHT ALONG THE WISCONSIN
BORDER.
MEDIUM RANGE GUIDANCE REMAINS REMARKABLY SIMILAR IN AMPLIFYING UPPER
FLOW ACROSS THE CONUS TUESDAY NIGHT INTO WEDNESDAY...AS SYSTEM
CURRENTLY SEEN NEAR 150W 40N IN NORTHERN HEMISPHERIC WATER VAPOR
IMAGERY AMPLIFIES ALONG THE WEST COAST AND INDUCES BROAD DOWNSTREAM
RIDGE ACROSS OUR REGION. GUIDANCE MAINTAINS TREND OF UPPER TROUGH
DIGGING ACROSS THE FOUR CORNERS REGION BY 12Z WEDNESDAY...WITH
SURFACE CYCLOGENESIS OCCURRING OVER THE TX/OK PANHANDLE REGION.
UPPER TROUGH THEN ADVANCES ACROSS THE PLAINS...BECOMING NEGATIVELY
TILTED ACROSS THE MIDWEST AND EVENTUALLY CLOSING OFF THE MID-LEVEL
CIRCULATION OVER THE WESTERN GREAT LAKES ON THURSDAY. THE ASSOCIATED
SURFACE LOW MEANWHILE...DEEPENS AS IT TREKS NORTHEAST ACROSS
MISSOURI AND ILLINOIS LATE WEDNESDAY NIGHT/THURSDAY MORNING AND INTO
LOWER MICHIGAN BY THURSDAY EVENING. WHILE MODEL SOLUTIONS HAVE BEEN
FAIRLY STEADY IN THEIR DEPICTION OF THE OVERALL SCENARIO FOR THE
PAST FEW DAYS OF MODEL RUNS...SOME DETAIL DIFFERENCES DO REMAIN WITH
RESPECT TO THE TRACK OF THE SURFACE LOW. 00Z GEFS ENSEMBLE
CLUSTERING HAS TIGHTENED UP FROM ITS 12Z RUN YESTERDAY...WITH A
MEDIAN SOLUTION TRACK JUST SOUTHEAST OF CHICAGO. THE NAM/SREF ARE
THE FARTHEST WEST...ACTUALLY TAKING THE LOW ACROSS FAR NORTHWEST IL.
THE 00Z GEM FOLLOWS A SIMILAR TRACK...THOUGH IS SLOWER BY A GOOD 6+
HOURS. THE 00Z ECMWF IS SIMILAR IN SPEED/TIMING TO THE GEM...THOUGH
TRACKS FARTHER TO THE RIGHT ALONG A DANVILLE-GOSHEN LINE...OR ABOUT
50 MILES WEST OF THE 12Z ECMWF TRACK. OFTEN...DEEPENING NEGATIVELY
TILTED STORM SYSTEMS EMERGING FROM THE SOUTHWEST TEND TO BE
DEEPER...SLOWER AND TRACK FARTHER TO THE WEST/NORTHWEST THAN MODELS
INITIALLY FORECAST...SO PERHAPS IT IS NOT TOO SURPRISING TO SEE THE
ECMWF TREND BACK NORTHWEST JUST A BIT. AT THIS POINT...HAVE BASED
FORECAST ALONG THE LINES OF A 00Z GEM/00Z ECMWF BLEND ALLOWING FOR
THE SLOWER TIMING OF THESE TWO SOLUTIONS...WITH A LOW TRACK THAT AT
LEAST INITIALLY WRAPS WARMER AIR AND RAIN INTO THE EASTERN HALF OF
THE CWA. THUS HAVE MAINTAINED A PROGRESSION OF RAIN/SNOW
NORTHWEST...RAIN EAST...EVENTUALLY CHANGING TO ALL SNOW AS THE LOW
PASSES THURSDAY AND COLD AIR WRAPS INTO THE DEPARTING LOW. WILL
CONTINUE TO HIGHLIGHT THE POTENTIAL FOR A SIGNIFICANT STORM ACROSS
THE REGION IN THE HWO...THOUGH STILL A BIT EARLY TO NAIL DOWN WHERE
SPECIFIC SNOW AMOUNTS WOULD FALL EXCEPT THE CONCEPT OF MORE ACROSS
THE NORTHWEST PART OF THE CWA AND SIGNIFICANTLY LESS IN THE
SOUTHEAST. IN ADDITION TO THE POTENTIAL FOR SNOW...VERY WINDY
CONDITIONS ARE ANTICIPATED BY THURSDAY NIGHT...AS THE DEEPENING LOW
MOVES INTO LOWER MICHIGAN...WITH NORTHWEST WINDS POTENTIALLY GUSTING
INTO THE 45 MPH RANGE.
A BRIEF PERIOD OF COLDER BUT QUIET WEATHER MOVES INTO THE AREA
FRIDAY THROUGH THE WEEKEND...WITH SOME LINGERING SNOW SHOWERS
DOWNWIND OF LAKE MICHIGAN INTO INDIANA/MICHIGAN.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* LENGTH OF TIME MVFR AND LOCALIZED IFR CEILINGS WILL HOLD ON
INTO THE EVENING/TONIGHT AND IF WILL REMAIN AOA 015 THRESHOLD
WHICH HAS OPERATIONAL IMPACTS ON ORD AND MDW TRAFFIC.
TRS
//DISCUSSION...UPDATED 18Z...
WIDESPREAD MVFR STRATUS ACROSS THE REGION WITH CEILINGS DOWN TO
IFR WELL OFF TO THE W THROUGH NW ACROSS IA...MN AND SE WI. VERY
WEEK PRESSURE GRADIENT ACROSS THE REGION SO LOW LEVEL FLOW IS IF
NOT NIL THEN VERY LIGHT. AS THE AFTERNOON PROGRESSES AND THROUGH
THE EVENING A WEAK RIDGE OF HIGH PRESSURE WILL BUILD SE FROM MN
AND WI TO OVER THE LOCAL AREA. WINDS SHOULD GENERALLY FAVOR A NW
TO N DIRECTION BUT REMAIN IN THE 3 TO 6 KT RANGE AND THEN BECOME
LIGHT AND VARIABLE OR CALM AGAIN AS THE RIDGE AXIS SETTLES OVER
THE LOCAL TERMINALS TONIGHT.
BY 12Z TUE LOW PRESSURE IS TO HAVE MOVED E FROM THE CENTRAL
PLAINS TO AROUND THE WESTERN IA AREA. IN RESPONSE WINDS BY
DAYBREAK SHOULD HAVE TURNED TO OUT SSE AS THE LOW CONTINUES TO
APPROACH THE AREA FROM THE W.
THERE IS A SLIGHT CHANCE OF SOME VERY LIGHT PRECIPITATION DURING
THU ACROSS NORTHERN IL THOUGH MODELS INDICATING SIGNIFICANT
SATURATION PRESSURE DEFICITS PERSIST WHILE BEST ISENTROPIC
UPGLIDE/OMEGA MOVE OVER THE AREA DURING THE MORNING LEAVING
BETTER CHANCE OF LIGHT SNOWFALL ACROSS SOUTHERN MN AND CENTRAL
WI.
MODEL THERMAL PROFILES AND MOS GUIDANCE ALL SUGGESTING THAT THE
LOW LEVEL INVERSION WILL WEAKEN AND THE STRATUS CLOUDS WILL
DISSIPATE DURING THE NIGHT WHILE MID LEVEL CLOUDS SPREAD OVER THE
AREA AHEAD OF A SHORT WAVE CURRENTLY OVER ID MOVES E TO THE
PLAINS OVERNIGHT.
TRS
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN NIL/LIGHT AND VARIABLE WINDS INTO THE NIGHT.
* HIGH CONFIDENCE CEILINGS WILL REMAIN AOA 015 THRESHOLD REST OF
DAY.
* MODERATE CONFIDENCE STRATUS DECK WILL DISSIPATE BUT CONFIDENCE
IN TIMING DURING THE OVERNIGHT IS LOW.
* HIGH CONFIDENCE THAT NO SIGNIFICANT PRECIPITATION WILL FALL OVER
THE LOCAL AREA.
TRS
//OUTLOOK FOR ORD/MDW FOR 00Z WEDNESDAY-12Z MONDAY...UPDATED 12Z...
* TUESDAY NIGHT AND WEDNESDAY...VFR.
* WEDNESDAY NIGHT...RAIN DEVELOPING. IFR POSSIBLE.
* THURSDAY...RAIN CHANGING TO SNOW. IFR/LIFR LIKELY. BECOMING
VERY WINDY WITH GUSTS 35+ KTS BY EVENING.
* THURSDAY NIGHT...VERY WINDY WITH GUSTS 35+ KT. SNOW ENDING.
BLOWING SNOW. LIFR IMPROVING TO MVFR.
* FRIDAY...GUSTY NORTHWEST WINDS. VFR.
* SATURDAY AND SUNDAY...VFR.
&&
.MARINE...
312 AM...NORTHWEST STORM FORCE WINDS TO 50 KT NOW EXPECTED BY
LATE THURSDAY AFTERNOON AND CONTINUING INTO THURSDAY NIGHT.
MAIN FORECAST CONCERN/CHALLENGE REMAINS THE POWERFUL WINTER STORM
EXPECTED TO MOVE ACROSS THE GREAT LAKES REGION THURSDAY/THURSDAY
NIGHT. THERE REMAINS UNCERTAINTY REGARDING THE EXACT TRACK OF THE
LOW FROM THE VARIOUS FORECAST MODELS THOUGH THERE IS SOME
CONSENSUS THAT THIS STORM WILL TRACK VERY CLOSE TO OR PERHAPS OVER
SOUTHERN LAKE MICHIGAN. THE STORM WILL BE IN THE PROCESS OF
RAPIDLY DEEPENING DURING THIS TIME. IF THIS STORM DOES INDEED
FOLLOW THIS TRACK...WINDS WILL RAPIDLY INCREASE THURSDAY
AFTERNOON AND CONTINUE INTO THURSDAY NIGHT WITH FORECAST SOUNDINGS
SHOWING GUSTS INTO THE 45-50KT RANGE WHICH COULD BE TOO LOW THOUGH
STRONGEST WINDS PROBABLY WOULD ONLY LAST 4-8 HOURS THOUGH GALES
SHOULD PERSIST WELL INTO FRIDAY AS THEY SLOWLY RELAX INTO FRIDAY
EVENING.
IN THE SHORTER TERM...LOW PRESSURE OVER THE NORTHERN LAKES WILL
LIFT NORTH TODAY AND WEAKEN...THIS WILL MAINTAIN A MODEST WESTERLY
GRADIENT OVER THE NORTHERN HALF OF THE LAKE THIS MORNING. WINDS
WILL TURN NORTHERLY OVER THE SOUTH END OF THE LAKE AHEAD OF A WEAK
RIDGE OF HIGH PRESSURE WHICH WILL MOVE ACROSS THE WESTERN LAKES
OVERNIGHT. ANOTHER LOW WILL BE MOVING NORTHEAST ACROSS THE OHIO
VALLEY THIS AFTERNOON AND DEEPENING AS IT MOVES TOWARD NEW ENGLAND
ON TUESDAY. SO HOW STRONG THE NORTHERLY GRADIENT BECOMES ON THE
SOUTH END OF THE LAKE LATER TODAY WILL NEED TO BE MONITORED.
ANOTHER FAST MOVING LOW WILL MOVE ACROSS THE IL/WI REGION ON
TUESDAY AND THEN ACROSS SOUTHERN LAKE MICHIGAN TUESDAY EVENING.
THE GRADIENT MAY INCREASE ENOUGH TO SUPPORT 15-25 KT ON THE FAR
SOUTH END OF THE LAKE AHEAD OF THE LOW AND AGAIN FROM THE WEST
TUESDAY EVENING AS THE LOW PASSES. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1157 AM CST MON DEC 17 2012
.DISCUSSION...
ISSUED 1040 AM CST MON DEC 17 2012
UPDATING THE FORECAST TO INCREASE RAIN CHANCES TODAY SE OF THE IL RIVER
WITH LIKELY POPS AND ALSO COOLING THE HIGHS A BIT WITH LOW CLOUDS
LINGERING ALL DAY. SLEET MAY BE MIXED IN WITH THE RAIN LATE THIS
MORNING NORTH OF I-72. JUST HAD A REPORT OF SLEET WITH THE RAIN AT
MOUNT PULASKI IN SE LOGAN COUNTY AROUND 1030 AM. HIGHS MOSTLY IN
THE LOW TO MID 40S THIS AFTERNOON...RANGING FROM THE UPPER 30S TO
NEAR 40F OVER THE IL RIVER VALLEY IN THE NW TO THE UPPER 40S AND
LOWER 50S NEAR THE WABASH RIVER. THUNDERSTORM CURRENTLY JUST EAST
OF LAWRENCE COUNTY AND LIFTING NE ACROSS SW INDIANA. SPC HAS THUNDERSTORM
CHANCES SE OF I-70 TODAY WHILE SLIGHT RISK OF SEVERE STORM IS OVER
CENTRAL/WESTERN KY...MID TN AND FAR SE INDIANA.
1004 MB LOW PRESSURE ALONG THE KY/IL BORDER BETWEEN EVANSVILLE AND
PADUCAH TO LIFT NE INTO SOUTHERN OH BY THIS EVENING. MEANWHILE A
SHORT WAVE NEAR KC TO MOVE ACROSS SOUTHERN IL THIS EVENING. THIS
TO KEEP A GOOD CHANCE OF RAIN SHOWERS TODAY SE OF THE IL RIVER AND
LINGERING IN EASTERN/SE IL THIS EVENING. NNE WINDS LESS THAN 10
MPH TO TURN NW LATER THIS AFTERNOON AND EVENING.
07
&&
.AVIATION...
ISSUED 1155 AM CST MON DEC 17 2012
IFR TO MVFR VSBYS AND CEILINGS EXPECTED THIS AFTERNOON ACROSS THE
CENTRAL IL TERMINAL AIRPORTS WITH A MIXTURE OF RAIN/SNOW SHOWERS SE
OF THE IL RIVER/PIA. JUST HAVE VCSH AT PIA WITH LIGHT FOG/HAZE 5-6
MILES WHICH WILL BE ON NORTHWEST EDGE OF PRECIPITATION TODAY.
PRECIPITATION SHOULD DIMINISH FROM WEST TO EAST LATER THIS
AFTERNOON AND EARLY EVENING BETWEEN 21Z-03Z. CLOUD BASES OF
500-1500 FT EXPECTED TO ELEVATE TO VFR DURING TONIGHT FROM WEST TO
EAST...THOUGH NOT A CMI IN EASTERN IL UNTIL LATER TONIGHT...AFTER
09Z. 1003 MB LOW PRESSURE DEEPENING A BIT NEAR EVANSVILLE ALONG
THE IN/KY BORDER TO LIFT NE INTO THE MID ATLANTIC STATES BY
06Z/MIDNIGHT TONIGHT. MEANWHILE A SHORT WAVE NEAR KC TO MOVE EAST
ACROSS SOUTHERN IL THIS EVENING...WHILE ANOTHER SHORT WAVE OVER
THE NORTHERN ROCKIES MOVE EAST INTO IA BY 18Z/NOON TUE. MODELS
HAVE BEEN TOO QUICK TO CLEAR OUT LOW CLOUDS AND TOOK A MORE
PESTIMISTIC ROUTE WITH KEEPING LOW CLOUDS AROUND LONGER INTO
TONIGHT. NNE WINDS 4-8 KTS TURNING NW DURING THE AFTERNOON AND
EVENING AND THEN BECOME BREEZY SSW TUE MORNING AHEAD OF 1001 MB
SURFACE LOW PRESSURE MOVING INTO CENTRAL/EASTERN IA BY MIDDAY TUE.
INCREASING WINDS SHOULD LIFT OUT LOW CLOUDS WHILE BAND OF MID
LEVEL CLOUDS POSSIBLE LATE TONIGHT INTO TUE MORNING.
07
&&
.PREV DISCUSSION...
ISSUED 230 AM CST MON DEC 17 2012
PRIMARY FOCUS FOR THIS FORECAST INVOLVES THE MAJOR STORM SYSTEM
THAT WILL BE CROSSING THE MIDWEST WEDNESDAY NIGHT AND THURSDAY...
INCLUDING PRECIPITATION TYPES AND STRONG WINDS. RAIN POTENTIAL
LATER TODAY IS A SECONDARY CONCERN.
SHORT TERM...TODAY THROUGH TUESDAY...
MAIN FOCUS FOR ANY RAIN TODAY IS WITH A SURFACE LOW CURRENTLY OVER
SOUTH CENTRAL MISSOURI...WITH A FRONTAL BOUNDARY ARCING NORTHEAST
ALONG THE OHIO RIVER. BEST PRECIPITATION CHANCES WILL BE NEAR THE
OHIO VALLEY AS THE LOW RIDES UP THE BOUNDARY...BUT SOME OF THE
RAIN FROM THIS SYSTEM MAY REACH INTO SOUTHEAST ILLINOIS. IN
ADDITION...A SHORTWAVE CURRENTLY OVER KANSAS/OKLAHOMA WILL SWING
ACROSS ILLINOIS THIS AFTERNOON. GFS AND CANADIAN MODELS DEVELOP
SOME LIGHT QPF FROM MISSOURI NORTHEAST INTO CENTRAL ILLINOIS
PRIMARILY THIS AFTERNOON...ALTHOUGH SOUNDINGS OFF THE RAP MODEL
SHOW QUITE A BIT OF DRY AIR ABOVE THE PERSISTENT INVERSION AROUND
900 MB. HIGHEST POPS TODAY WILL MAINLY BE SOUTH OF I-72...BUT WILL
CARRY SOME SLIGHTS NORTHWEST OF THE ILLINOIS RIVER. ANOTHER
SHORTWAVE WILL TRACK INTO THE WESTERN GREAT LAKES ON TUESDAY...BUT
IT STILL APPEARS ANY ASSOCIATED PRECIP WITH THIS FEATURE WILL
REMAIN TO OUR NORTH.
LONG TERM...WEDNESDAY THROUGH SUNDAY...
A STRONG UPPER WAVE COMING ONTO THE PACIFIC COAST ON TUESDAY IS
STILL ON TRACK TO HELP DEVELOP A MAJOR STORM SYSTEM ACROSS THE
CENTRAL PLAINS ON WEDNESDAY. STILL A FAIR AMOUNT OF SPREAD AMONG
THE EVENING MODELS ON TIMING AND PLACEMENT OF THE CENTRAL
LOW. EACH MODEL SHOWING SOME CONSISTENCY WITH ITS PREVIOUS
RUN...BUT NOT AMONGST EACH OTHER...WITH THE NAM THE FURTHEST
NORTHWEST AND THE ECMWF THE FURTHEST SOUTH. THIS IS GOING TO BE
CRITICAL IN DETERMINING THE EXACT PLACEMENT OF HEAVY SNOW ACROSS
PORTIONS OF THE MIDWEST. GIVEN THAT THE PARENT WAVE HAS NOT BEEN
ADEQUATELY SAMPLED BY THE UPPER AIR NETWORK YET...THESE
INCONSISTENCIES ARE NOT UNUSUAL.
THIS FORECAST PACKAGE WILL GO WITH A GFS/ECMWF BLEND...WITH THE
LOW ROUGHLY PARALLELING THE ILLINOIS RIVER LATE WEDNESDAY NIGHT
AND EARLY THURSDAY. RAIN IS EXPECTED TO OVERSPREAD THE AREA
WEDNESDAY EVENING...WITH SOME POTENTIAL FOR THUNDER IN THE
SOUTHEAST CWA LATE WEDNESDAY NIGHT IN THE WARM SECTOR. THE COLD
AIR WILL RAPIDLY POUR IN BEHIND THE LOW ON THURSDAY MORNING...WITH
FORECAST SOUNDINGS SHOWING A FAIRLY CLEAN AND RAPID TRANSITION
FROM RAIN TO SNOW GOING FROM WEST TO EAST ACROSS THE CWA. HEAVIEST
SNOWFALL IN THE DEFORMATION ZONE WOULD BE MORE ACROSS EASTERN IOWA
INTO SOUTHERN WISCONSIN...BUT AN INCH OR TWO OF SNOW IS POSSIBLE
NORTH OF A BLOOMINGTON TO CANTON LINE. ACCUMULATIONS MAY BE
HAMPERED BY THE UNSEASONABLY WARM GROUND...BUT A HEAVY FALLING
SNOW MAY BE ENOUGH TO OVERCOME THAT. WHAT SNOW DOES FALL WILL BLOW
AROUND QUITE A BIT...AS ALL MODELS SHOW VERY WINDY CONDITIONS
DEVELOPING THURSDAY AS THE LOW PULLS AWAY. BUFKIT SOUNDINGS OFF
THE GFS SHOW SURFACE GUSTS AROUND 45 MPH THURSDAY AFTERNOON AND
EARLY EVENING. ANY LINGERING SNOW SHOULD TAPER OFF THURSDAY
EVENING.
THE REMAINDER OF THE FORECAST PERIOD IS EXPECTED TO BE QUIET...
WITH TEMPERATURES RUNNING BELOW NORMAL.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1043 AM CST MON DEC 17 2012
.DISCUSSION...
ISSUED 1040 AM CST MON DEC 17 2012
UPDATING THE FORECAST TO INCREASE RAIN CHANCES TODAY SE OF THE IL RIVER
WITH LIKELY POPS AND ALSO COOLING THE HIGHS A BIT WITH LOW CLOUDS
LINGERING ALL DAY. SLEET MAY BE MIXED IN WITH THE RAIN LATE THIS
MORNING NORTH OF I-72. JUST HAD A REPORT OF SLEET WITH THE RAIN AT
MOUNT PULASKI IN SE LOGAN COUNTY AROUND 1030 AM. HIGHS MOSTLY IN
THE LOW TO MID 40S THIS AFTERNOON...RANGING FROM THE UPPER 30S TO
NEAR 40F OVER THE IL RIVER VALLEY IN THE NW TO THE UPPER 40S AND
LOWER 50S NEAR THE WABASH RIVER. THUNDERSTORM CURRENTLY JUST EAST
OF LAWRENCE COUNTY AND LIFTING NE ACROSS SW INDIANA. SPC HAS THUNDERSTORM
CHANCES SE OF I-70 TODAY WHILE SLIGHT RISK OF SEVERE STORM IS OVER
CENTRAL/WESTERN KY...MID TN AND FAR SE INDIANA.
1004 MB LOW PRESSURE ALONG THE KY/IL BORDER BETWEEN EVANSVILLE AND
PADUCAH TO LIFT NE INTO SOUTHERN OH BY THIS EVENING. MEANWHILE A
SHORT WAVE NEAR KC TO MOVE ACROSS SOUTHERN IL THIS EVENING. THIS
TO KEEP A GOOD CHANCE OF RAIN SHOWERS TODAY SE OF THE IL RIVER AND
LINGERING IN EASTERN/SE IL THIS EVENING. NNE WINDS LESS THAN 10
MPH TO TURN NW LATER THIS AFTERNOON AND EVENING.
07
&&
.AVIATION...
ISSUED 520 AM CST MON DEC 17 2012
MVFR CONDTIONS...WITH LOCAL IFR CIGS...ARE EXPECTED TO CONTINUE
THIS FORECAST PERIOD. WEAK WEATHER SYSTEM WILL MOVE ACROSS THE
AREA TODAY WHICH MAY BRING SOME LIGHT RAIN TO PARTS OF THE
FORECAST AREA BUT COVERAGE STILL APPEARS TO BE TOO LIMITED TO
INCLUDE IN TAFS OTHER THAN VCSH. FORECAST SOUNDINGS AND TIME
HEIGHT CROSS SECTIONS CONTINUE TO SHOW THE MOISTURE TRAPPED
BELOW A RATHER STRONG LOW LEVEL INVERSION WHICH WILL BE VERY
SLOW TO BREAK OVER THE NEXT 12 TO 18 HOURS. MODELS CONTINUE TO
SUGGEST IN THE WAKE OF THE WEATHER SYSTEM THAT MOVES THRU THE
AREA TODAY...SOME BREAK UP OF THE MOISTURE MAY OCCUR IN THE LOW
LEVELS BUT WILL BE A BIT MORE CONSERVATIVE THAN WHAT MODELS WERE
INDICATING FOR THIS AFTN. WILL BRING CIGS UP TO VFR IN MOST
LOCATIONS...EXCEPT CMI...AFTER 00Z. SURFACE WINDS WILL REMAIN
LIGHT TODAY...MOSTLY OUT OF A NORTHERLY DIRECTION.
SMITH
&&
.PREV DISCUSSION...
ISSUED 230 AM CST MON DEC 17 2012
PRIMARY FOCUS FOR THIS FORECAST INVOLVES THE MAJOR STORM SYSTEM
THAT WILL BE CROSSING THE MIDWEST WEDNESDAY NIGHT AND THURSDAY...
INCLUDING PRECIPITATION TYPES AND STRONG WINDS. RAIN POTENTIAL
LATER TODAY IS A SECONDARY CONCERN.
SHORT TERM...TODAY THROUGH TUESDAY...
MAIN FOCUS FOR ANY RAIN TODAY IS WITH A SURFACE LOW CURRENTLY OVER
SOUTH CENTRAL MISSOURI...WITH A FRONTAL BOUNDARY ARCING NORTHEAST
ALONG THE OHIO RIVER. BEST PRECIPITATION CHANCES WILL BE NEAR THE
OHIO VALLEY AS THE LOW RIDES UP THE BOUNDARY...BUT SOME OF THE
RAIN FROM THIS SYSTEM MAY REACH INTO SOUTHEAST ILLINOIS. IN
ADDITION...A SHORTWAVE CURRENTLY OVER KANSAS/OKLAHOMA WILL SWING
ACROSS ILLINOIS THIS AFTERNOON. GFS AND CANADIAN MODELS DEVELOP
SOME LIGHT QPF FROM MISSOURI NORTHEAST INTO CENTRAL ILLINOIS
PRIMARILY THIS AFTERNOON...ALTHOUGH SOUNDINGS OFF THE RAP MODEL
SHOW QUITE A BIT OF DRY AIR ABOVE THE PERSISTENT INVERSION AROUND
900 MB. HIGHEST POPS TODAY WILL MAINLY BE SOUTH OF I-72...BUT WILL
CARRY SOME SLIGHTS NORTHWEST OF THE ILLINOIS RIVER. ANOTHER
SHORTWAVE WILL TRACK INTO THE WESTERN GREAT LAKES ON TUESDAY...BUT
IT STILL APPEARS ANY ASSOCIATED PRECIP WITH THIS FEATURE WILL
REMAIN TO OUR NORTH.
LONG TERM...WEDNESDAY THROUGH SUNDAY...
A STRONG UPPER WAVE COMING ONTO THE PACIFIC COAST ON TUESDAY IS
STILL ON TRACK TO HELP DEVELOP A MAJOR STORM SYSTEM ACROSS THE
CENTRAL PLAINS ON WEDNESDAY. STILL A FAIR AMOUNT OF SPREAD AMONG
THE EVENING MODELS ON TIMING AND PLACEMENT OF THE CENTRAL
LOW. EACH MODEL SHOWING SOME CONSISTENCY WITH ITS PREVIOUS
RUN...BUT NOT AMONGST EACH OTHER...WITH THE NAM THE FURTHEST
NORTHWEST AND THE ECMWF THE FURTHEST SOUTH. THIS IS GOING TO BE
CRITICAL IN DETERMINING THE EXACT PLACEMENT OF HEAVY SNOW ACROSS
PORTIONS OF THE MIDWEST. GIVEN THAT THE PARENT WAVE HAS NOT BEEN
ADEQUATELY SAMPLED BY THE UPPER AIR NETWORK YET...THESE
INCONSISTENCIES ARE NOT UNUSUAL.
THIS FORECAST PACKAGE WILL GO WITH A GFS/ECMWF BLEND...WITH THE
LOW ROUGHLY PARALLELING THE ILLINOIS RIVER LATE WEDNESDAY NIGHT
AND EARLY THURSDAY. RAIN IS EXPECTED TO OVERSPREAD THE AREA
WEDNESDAY EVENING...WITH SOME POTENTIAL FOR THUNDER IN THE
SOUTHEAST CWA LATE WEDNESDAY NIGHT IN THE WARM SECTOR. THE COLD
AIR WILL RAPIDLY POUR IN BEHIND THE LOW ON THURSDAY MORNING...WITH
FORECAST SOUNDINGS SHOWING A FAIRLY CLEAN AND RAPID TRANSITION
FROM RAIN TO SNOW GOING FROM WEST TO EAST ACROSS THE CWA. HEAVIEST
SNOWFALL IN THE DEFORMATION ZONE WOULD BE MORE ACROSS EASTERN IOWA
INTO SOUTHERN WISCONSIN...BUT AN INCH OR TWO OF SNOW IS POSSIBLE
NORTH OF A BLOOMINGTON TO CANTON LINE. ACCUMULATIONS MAY BE
HAMPERED BY THE UNSEASONABLY WARM GROUND...BUT A HEAVY FALLING
SNOW MAY BE ENOUGH TO OVERCOME THAT. WHAT SNOW DOES FALL WILL BLOW
AROUND QUITE A BIT...AS ALL MODELS SHOW VERY WINDY CONDITIONS
DEVELOPING THURSDAY AS THE LOW PULLS AWAY. BUFKIT SOUNDINGS OFF
THE GFS SHOW SURFACE GUSTS AROUND 45 MPH THURSDAY AFTERNOON AND
EARLY EVENING. ANY LINGERING SNOW SHOULD TAPER OFF THURSDAY
EVENING.
THE REMAINDER OF THE FORECAST PERIOD IS EXPECTED TO BE QUIET...
WITH TEMPERATURES RUNNING BELOW NORMAL.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
330 PM CST MON DEC 17 2012
.SYNOPSIS...
LIGHT WINDS AND LINGERING LOW LEVEL MOISTURE HAS KEPT LOW CLOUDS AND
LIGHT FOG IN PLACE TODAY ACROSS THE FORECAST AREA. AS A RESULT...
TEMPERATURES HAVE STRUGGLED TO CLIMB...HAVING ONLY REACHED THE UPPER
20S NORTH TO MID 30S SOUTH THIS AFTERNOON. MSAS ANALYSIS INDICATED A
RIDGE OF HIGH PRESSURE REACHED FROM TX TO MN...FLANKED BY LOW
PRESSURE MOVING ALONG A COLD FRONT IN NORTHERN KY TO THE SE...AND A
LEE TROUGH REACHING FROM NORTHERN MT TO EASTERN CO. IN THE UPPER
LEVELS...A TROUGH AXIS REACHED FROM THE EASTERN DAKOTAS TO THE MO
BOOTHEEL REGION. UPSTREAM...12Z ANALYSIS INDICATED A 160 KT JET AT
300 MT MOVING IN THE STRONG...NEARLY ZONAL FLOW...ACROSS NORTHERN CA
INTO THE GREAT BASIN REGION. AN UPPER LOW WAS OFF THE NORTHERN BC
COAST WITH A TROUGH AXIS EXTENDING S-SW INTO THE PACIFIC.
&&
.SHORT TERM...TONIGHT AND TUESDAY...
DEVELOPING ACTIVE PATTERN WILL SEND ANOTHER ROUND OF PRECIPITATION
THROUGH THE REGION TONIGHT INTO EARLY TUESDAY. FORECAST CHALLENGES
CENTER ON THIS PRECIPITATION LATE TONIGHT INTO TUESDAY...ALONG WITH
LOW CLOUDS AND FOG.
LATEST VISIBLE SATELLITE IMAGES SHOW AN AREA OF CLOUDS OVER NORTH
CENTRAL MO INTO SOUTHERN IA...SLOWLY MIGRATING EASTWARD WITH THE
UPPER LEVEL TROUGH. AS THIS EXTENDS EASTWARD INTO THE SOUTHERN THIRD
OF THE FORECAST AREA AROUND SUNSET...THERE WILL BE A POTENTIAL FOR
THICKENING OF THE FOG THAT HAS LINGERED OVER SE IA AND ADJACENT
AREAS OF MO AND IL THIS EVENING. BASED ON LATEST RAP LOW LEVEL
MOISTURE FIELDS...STRATUS WILL LIKELY REMAIN IN PLACE THROUGH THE
NIGHT OVER THE REMAINDER OF THE FORECAST AREA...AND LIKELY FILL BACK
IN ANY HOLES THAT DEVELOP ACROSS THE SOUTH. WILL GO WITH PATCHY FOG
WORDING FOR NOW AND MONITOR THE SOUTH THIS EVENING FOR POSSIBLE
UPDATES TO MORE DENSE OR WIDESPREAD COVERAGE. A STRIKE AGAINST FOG
TONIGHT WILL BE THE INCOMING SUBSIDENCE BEHIND THE UPPER LEVEL WAVE
AND INCREASING WINDS TOWARD MORNING AS A SURFACE LOW APPROACHES.
AS SEEN TODAY...CLOUDS...LINGERING MOISTURE AND WEAK WINDS WILL
LIMIT DIURNAL TEMPERATURE CURVES AND HAVE KEPT MINS CLOSE TO CURRENT
DEWPOINTS...FROM THE MID 20S NORTH TO LOWER 30S SOUTH.
THE FOCUS THEN TURNS TO AN IMPULSE IN THE FAST ZONAL FLOW ALOFT THAT
WAS MOVING ACROSS CENTRAL ID AT MIDDAY. MODELS DEVELOP THIS INTO A
CLIPPER LIKE LOW PRESSURE SYSTEM AS THE ENERGY MOVES OVER THE LEE
TROUGH TONIGHT. THIS FAST MOVING LOW DEVELOPS OVER NEB LATE
TONIGHT...THEN HEADS EASTWARD OVER THE FORECAST AREA DURING THE
DAY TUESDAY. HAVE GENERALLY FOLLOWED A BLEND OF THE GFS/ECMWF AND
GEM WITH THIS FEATURE...WHICH DEVELOPS A NW TO SE ORIENTED WARM
ADVECTION WING OF LIGHT SNOW OVER THE CENTRAL PART OF THE FORECAST
AREA BETWEEN 06Z AND 12Z AND HAVE KEPT CHANCE POPS THERE. THE
POTENTIAL FOR LIGHT SNOW OR FLURRIES SHOULD THEN SHIFT TO THE FAR
NORTH AND NORTHEAST BY AFTERNOON AS THE LOW MOVES TOWARD CHICAGO.
WITH LIMITED MOISTURE AND RAPID PROGRESSION...SNOWFALL AMOUNTS
SHOULD BE WELL BELOW AN INCH IN MOST LOCATIONS WITH THE BEST CHANCES
OF A LIGHT COATING NORTH OF THE HIGHWAY 30 CORRIDOR. HAVE TRENDED
SOME PARTIAL CLEARING FROM SW TO NE IN THE AFTERNOON...BUT THIS MAY
END UP BEING TOO OPTIMISTIC DUE TO THE LINGERING MOISTURE AND
CYCLONIC FLOW THROUGH THE AFTERNOON. BRISK WESTERLY WINDS IN THE FAR
SOUTH MAY ALLOW TEMPERATURES TO REACH THE UPPER 40S...WHILE HIGHS IN
THE NORTH ARE KEPT IN THE UPPER 30S.
SHEETS
.LONG TERM...TUESDAY NIGHT THROUGH NEXT MONDAY...
ALL LONG TERM FCST ENERGY INTO HANDLING MIDWEEK STORM SYSTEM...WITH
THE WEEKEND LOOKING IN BETWEEN SYSTEMS AND RATHER BENIGN/SEASONABLE
ANYWAY THROUGH EARLY MONDAY. ASSESSING THE LATEST 12Z MEDIUM RANGE
MODEL RUNS AS WELL AS THE NAM...SURPRISINGLY GOOD AGREEMENT WITH
GENERAL SFC LOW AND MID LEVEL LOW PATHS BUT WITH SOME TRACKING
SPEED AND STRENGTH VARIANCES. THIS TAKING INTO ACCOUNT BULK OF WAVE
ENERGY THAT WILL DRIVE THE STORM STILL OFF THE PACIFIC NORTHWEST
COAST AND SOUTH OF THE GULF OF AK. ALL MODELS BUT THE 12Z ECMWF THAT
IS. WHILE THE OTHERS HAVE TRENDED FURTHER NORTH AND WEST WITH THEIR
LATEST 12Z RUNS WHICH MAKE FOR MORE OF A PRECIP TYPE/AMOUNT CHALLENGE
FOR THE DVN CWA...THE CONSISTENT ECMWF WOULD STILL IMPACT MOST OF THE
LOCAL FCST AREA WITH A QUICKER SWITCH OVER TO SNOW AND MORE AREAS
STARTING OFF AS SNOW TO BEGIN WITH. THE ENSEMBLE SFC LOW TRACK OF
THE 12Z GFS/NAM/UKMET/GEM ALL HOOK THE DEVELOPING LOW FROM THE OK
PANHANDLE ON WED UP THROUGH NORTHEAST MO/WEST CENTRAL IL LATE WED
NIGHT...TO A NORTH CENTRAL IL POSITION BY THU MORNING...AND THEN
BOMB IT OUT ACRS LOWER MI INTO THU EVENING. THE 12Z EURO MAINTAINS
A TRACK FURTHER TO THE SOUTHEAST OF THE ENSEMBLE PATH...SOUTHWEST MO
TO NEAR THE STL AREA BY THU MORNING AND THEN OFF TO WEST CENTRAL
INDIANA BY EARLY THU AFTERNOON. THE ENSEMBLE OF SOLUTIONS BESIDES THE
ECMWF WOULD GENERALLY SUGGEST MUCH OF THE SOUTHEAST HALF TO TWO
THIRDS OF THE FCST AREA TO BE RAIN OR EVEN EXPERIENCE SOME
CONVECTION THROUGH MIDNIGHT WED NIGHT...WHILE THE NORTHWEST THIRD
MIXES AND DYNAMICALLY COOLS INTO WET ACCUMULATING SNOW AFTER 03Z
THU. AS DEF ZONE CONTINUES TO FORM AND LLVL COLD CONVEYOR IN-WRAPS
AND INCREASES...THESE MODELS GENERALLY SUGGEST THE SWITCH OVER TO
WET SNOW TO CONTINUE FROM WEST-NORTHWEST TO THE EAST AFTER MIDNIGHT
AND INTO EARLY THU MORNING ACRS THE DVN CWA. 3-7 INCHES POSSIBLE BY
12Z THU ALONG AND WEST OF A LINE FROM SIGOURNEY IA...TO EAST OF
CEDAR RAPIDS AND TO WEST OF DBQ. SOME ADDITIONAL ACCUMS OF 1-2
INCHES IN THESE AREAS POSSIBLE THROUGH 18Z THU...BUT BULK OF
ACCUMULATING SNOW TO SWITCH EASTWARD ACRS THE REST OF THE CWA WITH 3-
6 INCHES POSSIBLE ALONG AND NORTH OF A LINE FROM MT PLEASANT IA...TO
THE QUAD CITIES..AND TO STERLING IL.
WHILE THE NORTHWEST THIRD AND NORTH CENTRAL PORTIONS OF THE DVN CWA
MAY EVENTUALLY GET 4-8+ INCHES BY THU EVENING...THE ENSEMBLES MINUS
THE ECMWF SUGGEST THE HIGHEST SNOWFALL TOTALS OF 8-12+ INCHES OCCUR
WEST AND NORTH OF THE DVN CWA ACRS SOUTH CENTRAL IA...UP THROUGH
NORTHEASTERN IA INTO SW/CENTRAL WI. EXTENT OF BOMBING CYCLONE TO THE
EAST STILL INDICATED BY BULK OF THE MODEL RUNS TO DRIVE VERY STRONG
NORTH BECOMING NORTHWEST WINDS LATE WED NIGHT AND ESPECIALLY ON
THU...SUSTAINED 25 TO 35 MPH WITH GUSTS TO AT LEAST 45 MPH. GRAVITY
WAVE PHENOMENA WEST OF RAPIDLY DEEPENING CYCLONE COULD ALSO PRODUCE
ISOLATED GUSTS OVER 50 MPH AT MAX DEEPENING STAGE ON THU. THUS WHERE
ACCUMULATING SNOWS OCCUR...NEAR BLIZZARD OR BLIZZARD CONDITIONS VERY
POSSIBLE. BACK TO THE ECMWF...IT/S TRACK WOULD MEAN MORE OF A DIRECT
HIT UPON THE LOCAL AREA AND HIGHER SNOW AMOUNTS FURTHER EAST AND
SOUTH...ESPECIALLY TAKING INTO ACCOUNT SOME FUJI-WARA EFFECT OF
SECONDARY VORT INTERACTING IN TROF BASE AND ENHANCING DEF ZONE SNOWS
ACRS THE LOCAL AREA ON THU. DESPITE ONGOING MODEL UNCERTAINTY AND
THE SYSTEM TO BE BETTER SAMPLED FOR THE 00Z RUNS TONIGHT AND
ESPECIALLY 12Z TUE...WILL ISSUE A WINTER STORM WATCH FOR ROUGHLY THE
NORTHWEST HALF OF THE DVN CWA FOR WED NIGHT AND THU GIVING A NOD
SOMEWHAT TO THE ENSEMBLE TRACK. THE STRONG WINDS LOOK TO BE A LARGE
IMPACT EVEN FOR ADVISORY LEVEL OR SLIGHTLY LESS SNOW AMOUNTS. DO FEEL
THE CWA WILL HAVE TO EVENTUALLY BE DIVIDED INTO WINTER STORM WARNING
AND ADVISORY AREAS...BUT WHERE AN WHEN STILL UP IN THE AIR. A
WATCHFUL EYE WILL ALSO NEED TO BE OPEN FOR TRENDS ON THE NEXT 1-2
MODEL RUNS BACK CLOSER TO THE CONSISTENT ECMWF...WHICH WOULD THEN
WARRANT THE NEED OF EXPANDING THE WATCH SOUTH AND EAST. ..12..
&&
.AVIATION...
STRATUS AND FOG WILL LIKELY REMAIN IN PLACE TONIGHT...WITH LATEST
TRENDS NOW SUGGESTING LIGHT SNOW OR FLURRIES MAY IMPACT CID...DBQ
AND POSSIBLY MLI TOWARD DAWN TUESDAY. LINGERING LOW LEVEL MOISTURE
AND LIGHT WINDS WILL CONTINUE IFR AND POSSIBLE LIFR CONDITIONS DUE
TO LOW CIGS AND FOG THROUGH THE NIGHT. A FAST MOVING LOW PRESSURE
SYSTEM MOVING OUT OF THE ROCKIES WILL SPREAD LIGHT SNOW OR FLURRIES
ACROSS EASTERN IA AND NW IL LATE TONIGHT AND INTO TUESDAY MORNING.
CONFIDENCE IS INCREASING THAT THIS PRECIPITATION MAY AFFECT AT LEAST
THE DBQ TERMINAL...AND THIS WILL LIKELY BE REFLECTED IN UPDATES THIS
EVENING. OTHERWISE...CURRENT FORECASTS HAVE CONDITIONS IMPROVING TO
MVFR AFTER SUNRISE TUESDAY. SHEETS
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
AFTERNOON FOR BENTON-BUCHANAN-CEDAR-CLINTON-DELAWARE-
DUBUQUE-HENRY IA-IOWA-JACKSON-JEFFERSON-JOHNSON-JONES-
KEOKUK-LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
AFTERNOON FOR JO DAVIESS-ROCK ISLAND.
MO...NONE.
&&
$$
SHEETS/12
AREA FORECAST DISCUSSION
NWS PADUCAH KY
1014 AM CST MON DEC 17 2012
.UPDATE...
ISSUED AT 1014 AM CST MON DEC 17 2012
UPDATED THE PUBLIC GRIDS TO REFLECT LATEST OBSERVATIONAL AND
GUIDANCE TRENDS. SOLID LOW OVERCAST CONDITIONS EXIST ALONG AND
NORTH OF A SURFACE BOUNDARY RUNNING FROM NEAR KPOF TO NEAR KEHR.
LATEST LAMP GUIDANCE IS QUITE PESSIMISTIC...KEEPING OVERCAST
CONDITIONS WELL INTO THIS EVENING. THE LATEST RUC AND NAM PUSH THE
BOUNDARY EASTWARD THROUGH THE AREA THIS AFTERNOON. THE LOW CLOUDS
SHOULD PUSH IN BEHIND THE BOUNDARY. THIS SHOULD LEAD TO LITTLE
WARMING BEHIND THE BOUNDARIES CURRENT LOCATION...AND SOME COOLING
THIS AFTERNOON ONCE THE FRONT MOVES THROUGH A GIVEN LOCATION. USED
RUC DATA TO ACHIEVE THESE ADJUSTMENTS.
AHEAD OF THE BOUNDARY...MAINLY OVER WEST KENTUCKY STRATOCU WILL
ALLOW SOME MODEST WARMING. HOWEVER...SIGNIFICANT DESTABILIZATION
WILL HAVE A HARD TIME DEVELOPING. FEEL THAT SHOWERS WILL
INCREASE/SPREAD EAST NORTHEAST ACROSS WEST KENTUCKY THROUGH EARLY
AFTERNOON...AND SOME THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE
LATER THIS AFTERNOON...AS IT MOVES OUT OF OUR FORECAST AREA. WILL
HAVE TO MONITOR CLOSELY THIS AFTERNOON...BUT WOULD BE SURPRISED TO
SEE ANYTHING MORE THAN AN ISOLATED HAIL OR WIND REPORT.
&&
.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 340 AM CST MON DEC 17 2012
SHOWERS CONTINUE TO DEVELOP ACROSS WEST KENTUCKY EARLY THIS
MORNING. MODELS ARE INDICATING LI`S ANYWHERE FROM -1 TO -5...AND
CAPE VALUES OF 300 TO 1000 J/KG ACROSS EXTREME SOUTHEAST
MISSOURI...WEST KENTUCKY...AND SOUTHWEST INDIANA TODAY...MAINLY
DURING THE MORNING HOURS. MODELS SHOW MINIMAL QPF ACROSS OUR
REGION TODAY...SO SLIGHT TO LOW CHANCE POPS RIGHT NOW LOOK
REASONABLE ACROSS THE AFOREMENTIONED REGIONS. SPC HAS THE EASTERN
THIRD OF THE PAH FORECAST AREA IN A SLIGHT RISK TODAY WHERE MODELS
ARE SHOWING THE BEST INSTABILITY. ACTIVITY SHOULD BEGIN TAPERING
OFF THIS AFTERNOON...AND ANY LINGERING PRECIP SHOULD MOVE OUT OF
THE REGION BY MID EVENING AT THE LATEST.
WINDS SWITCH TO THE NORTHWEST LATE TODAY AND INTO TONIGHT...WHICH
WILL BRIEFLY BRING IN COOLER AIR TO THE AREA. BY TUESDAY...WITH
SOME SUNSHINE AND A QUICK RETURN OF SOUTHERLY WINDS...TEMPERATURES
WILL CLIMB BACK INTO THE MIDDLE TO UPPER 50S. HIGH PRESSURE WILL
CONTINUE TO BUILD OVER THE SOUTHEAST U.S. FOR THE EARLY PART OF
THE WORK WEEK...KEEPING US DRY AND EXTREMELY MILD INTO WEDNESDAY.
CLOUDS WILL INCREASE WEDNESDAY AHEAD OF THE APPROACHING STRONG
COLD FRONT. ECMWF HINTS AT SOME PRECIP MAKING INTO OUR FAR
WEST COUNTIES BY LATE WEDNESDAY...SO KEPT A SLIGHT CHANCE OF
SHOWERS WEDNESDAY AFTERNOON FOR THE OZARK FOOTHILLS OF MISSOURI.
.LONG TERM...(WEDNESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 340 AM CST MON DEC 17 2012
VIGOROUS H5 WAVE IS FORECAST TO BE OVER THE FOUR CORNERS REGION
MIDDAY WEDNESDAY...AND RAPIDLY MOVE EAST INTO THE CENTRAL PLAINS BY
MIDNIGHT WEDNESDAY NIGHT. BY MIDDAY THURSDAY THE STRENGTHENING
WAVE SHOULD BE OVER CENTRAL ILLINOIS. SURFACE LOW PRESSURE IS
FORECAST TO TRACK NORTHEAST FROM NCNTRL OKLAHOMA WEDNESDAY EVENING
TO JUST NORTH OF ST. LOUIS THURSDAY MORNING TO SOUTH CENTRAL
MICHIGAN BY THURSDAY EVENING. THIS LOW TRACK IS BASED ON A CONSENSUS
TRACK SIMILAR TO YESTERDAY...AND CLOSE TO THE 12Z UKMET...ALL OF
WHICH IS A COMPROMISE TO THE FASTER/SLIGHTLY FARTHER NORTH TRACK
OF THE 00Z GFS VS. THE SLOWER FARTHER SOUTH 12Z/00Z ECMWF RUNS.
WENT INTO THE LOW END OF CATEGORICAL FOR POPS WEDNESDAY NIGHT.
TEMPS SHOULD REMAIN STEADY NEARLY ALL NIGHT GIVEN WELL ESTABLISHED
WARM SECTOR OVER THE AREA. PROSPECT FOR SEVERE WEATHER STILL HIGHLY
CONDITIONAL...MAINLY WITH RESPECT TO INSTABILITY. CANNOT RULE IT
OUT GIVEN THE STRENGTH AND DYNAMIC NATURE OF THE SYSTEM...RESULTANT
WIND FIELDS. BUT STILL REMAINS TO BE SEEN HOW MUCH OF A FAVORABLE
AIR MASS AND RESPECTABLE INSTABILITY WILL BE IN PLAY.
POPS SHOULD END FAIRLY QUICKLY FROM SW TO NE AS THE SYSTEM QUICKLY
DEPARTS THURSDAY. ABANDONED DIURNAL ASPECT AS STRONG WNW WINDS
AND CAA WILL ALLOW TEMPS AND DEW POINTS TO DROP SHARPLY THROUGH THE
DAY...ESPECIALLY THE MORNING HOURS IN THE WAKE OF THE FRONT.
LINGERED ONLY A SLIGHT CHANCE RW-/SW- UP ALONG THE I-64 CORRIDOR
THURSDAY AFTERNOON GIVEN THE QUICK SYSTEM DEPARTURE AND BETTER
MOISTURE TO OUR NORTH.
QUIET WEATHER FOR THE REMAINDER OF THE LONG TERM FORECAST...AS THE
MODELS DEVELOP A MUNDANE QUASI ZONAL FLOW PATTERN OVER MUCH OF
THE CONUS...SOME SLIGHT AMPLIFICATION TOWARD THE END OF THE
PERIOD. TEMPERATURES WILL BE CLOSE TO NORMAL THROUGH THE PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 541 AM CST MON DEC 17 2012
IFR TO LIFR CIGS AND MVFR TO IFR VSBYS EXPECTED THROUGH
18Z...THOUGH BOTH COULD BE HIGHLY VARIABLE. SHOWER CHANCES NOT
HIGH ENOUGH TO INCLUDE IN TAFS. OVERALL CONDITIONS SHOULD
IMPROVE BY A CATEGORY THIS AFTERNOON. LIGHT WINDS THIS MORNING
WILL BECOME WEST THEN NORTHWEST AT 6 TO 11 KTS THIS AFTERNOON AND
EVENING. VFR CONDITIONS WILL RETURN BETWEEN 05Z AND 10Z.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&
$$
UPDATE...DRS
SHORT TERM...RST
LONG TERM....CN
AVIATION...RST
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1241 PM EST MON DEC 17 2012
.SYNOPSIS...
ISSUED AT 315 AM EST MON DEC 17 2012
LOW PRESSURE OVER EASTERN LAKE SUPERIOR WILL WEAKEN AND MOVE TOWARD
JAMES BAY TODAY. CHANCES FOR RAIN AND SNOW WILL CONTINUE TO DECREASE
THROUGH TONIGHT AS THIS OCCURS. A WEAK LOW PRESSURE SYSTEM PASSING
TO OUR SOUTH MAY BRING LIGHT RAIN AND SNOW TUESDAY AFTERNOON INTO
TUESDAY NIGHT. A MUCH STRONGER SYSTEM WILL MOVE INTO THE REGION
THURSDAY...WITH WINTER STORM CONDITIONS EXPECTED IN AT LEAST SOME
PARTS OF THE GREAT LAKES REGION.
&&
.UPDATE...
ISSUED AT 1237 PM EST MON DEC 17 2012
LIGHT LAKE EFFECT SNOW AND RAIN SHOWERS CONTINUE ACROSS THE
FAVORED AREAS OF EASTERN UPPER AND NORTHWEST LOWER MICHIGAN AS
WEAKISH CAA CONTINUES. STILL EXPECT COVERAGE TO TAPER OFF RATHER
QUICKLY THROUGH THE AFTERNOON OVER NORTHWEST LOWER AS OFF THE DECK
DRYING FURTHER DEEPENS. LIGHT SNOW SHOWERS EXPECTED INTO THE EARLY
EVENING NEAR WHITEFISH BAY OVER EASTERN UPPER WITH MINIMAL
ACCUMULATIONS.
UPDATE ISSUED AT 1009 AM EST MON DEC 17 2012
BROAD TROUGHINESS REMAINS OVER THE GREAT LAKES...WITH ONE RATHER
COMPACT EMBEDDED VORT LOBE EXITING EASTERN UPPER MICHIGAN. LOW LEVEL
MOISTURE REMAINS ABUNDANT...AS EVIDENT BY WIDESPREAD STRATUS AND 12Z
LOCAL SOUNDING WHICH HAD A MOISTURE-RICH PROFILE UP THROUGH H80.
TOP-DOWN DRYING ALREADY EVIDENT JUST UPSTREAM...WITH KGRB SOUNDING
SHOWING RAPID DEPLETION OF MOISTURE ABOVE H85 CENTERED INVERSION.
THIS DRYING WILL CONTINUE TO SPREAD EAST...WITH A RAPID FALL-OFF OF
MID LEVEL MOISTURE INTO THIS AFTERNOON...ESPECIALLY ACROSS NORTHERN
LOWER MICHIGAN. COMBINE THIS WITH JUST MARGINALLY UNSTABLE LOW LEVEL
PROFILES OVER LAKE MICHIGAN (HIGH RES RAP ANALYSIS SHOWED -6C H85
AIR OVER THE BIG POND)...AND ONGOING LIGHT LAKE EFFECT SNOW/RAIN
SHOWERS SHOULD TAPER OFF THROUGH EARLY AFTERNOON. MOISTURE REMAINS
SOMEWHAT DEEPER OVER LAKE SUPERIOR...SUGGESTING LIGHT RAIN/SNOW
SHOWERS CONTINUING THROUGH MUCH OF THIS AFTERNOON...PERHAPS BRINGING
SOME VERY MINOR SNOW ACCUMULATIONS (SUB ONE INCH) OVER THE FAVORED
SNOWBELTS. TEMPERATURES LOOK TO REMAIN PRETTY STEADY-STATE IN THE
MID AND UPPER 30S AS DIURNAL INFLUENCES ARE COUNTERED BY WEAKISH LOW
LEVEL CAA. ABOVE WELL HANDLED BY INHERITED FORECAST WITH ONLY
COSMETIC CHANGES NEEDED TO ACCOUNT FOR REAL-TIME RADAR TRENDS.
UPDATE ISSUED AT 700 AM EST MON DEC 17 2012
SOME FINE-TUNING...PUSHING MORNING POPS A LITTLE FURTHER SOUTH
INTO THE HTL/CAD AREAS...AND KEEPING PRECIP MIXED A FEW MORE HOURS
IN EASTERN UPPER BEFORE GOING ALL SNOW. NEWLY ARRIVING STAFF
MEMBERS REPORT SEEING A FEW WET FLAKES MIXING IN ON THE
COMMUTE...SO HAVE ADDED IN A MIX A BIT SOONER OVER THE HIGH
TERRAIN IN THE GLR AREA.
&&
.SHORT TERM...(TODAY THROUGH TONIGHT)
ISSUED AT 315 AM EST MON DEC 17 2012
RATHER NEBULOUS FORECAST AS WE WELCOME THE NEW WORK WEEK...WITH MAIN
ISSUES BEING CLOUD COVER/TEMPS AND SMALL CHANCES FOR MAINLY NUISANCE
LAKE SNOW SHOWERS/FLURRIES. EARLY MORNING ANALYSIS PLACES WEAK
SURFACE LOW OVER THE EASTERN TIP OF LAKE SUPERIOR...WITH ITS
ASSOCIATED WEAK OCCLUDED FRONTAL BOUNDARY SLOWLY WORKING THROUGH
NORTHERN LOWER. JUST A SUBTLE WIND SHIFT WITH THIS FEATURE...BUT
WITH A SLIGHTLY COOLER AIR MASS GRADUALLY FILTERING INTO THE CWA
(STILL NOT VERY COLD FOR MID DECEMBER). REGIONAL RADAR MOSAIC SHOWS
EARLIER LAST BATCH OF SHOWERS EXITING THE AREA...AS WEAK SECONDARY
UPPER VORT IS TRACKING OVERHEAD...WHILE SATELLITE PICS/OBS SHOW
QUITE THE EXPANSIVE LOW STRATUS CLOUD DECK WELL ENTRENCHED ALL
THROUGHOUT THE GREAT LAKES/UPPER MIDWEST.
FOR TODAY...BROAD UPPER TROUGHING WILL CONTINUE TO DOMINATE THE
GREAT LAKES REGION...AS STRONGER SOUTHERN STREAM ENERGY LIFTS
THROUGH THE TENNESSEE VALLEY. AIRMASS THROUGH THE DAY WILL BECOME
INCREASINGLY COOL ALOFT (H8 TEMPS AROUND -6C BY MIDDAY) WHILE ALSO
DRYING OUT ACROSS NORTHERN LOWER. EASTERN UPPER WILL BE A DIFFERENT
STORY AS APPROACH OF YET ANOTHER WEAK SHORTWAVE BRINGS A BRIEF ROUND
OF DEEPER MOISTURE ACROSS EASTERN LAKE SUPERIOR. THAT SETUP IN
COMBINATION WITH MARGINAL LAKE INSTABILITY SHOULD GIVEN AT LEAST
DECENT COVERAGE OF MAINLY LIGHT LAKE SNOW SHOWERS THROUGH THE DAY
ACROSS NORTHERN CHIPPEWA COUNTY IN A MEAN WEST/NORTHWEST FLOW
REGIME. ACCUMULATIONS SHOULD BE HINDERED BY SURFACE TEMPS AT OR
SLIGHTLY ABOVE FREEZING...BUT PERHAPS UP TO AN INCH COULD FALL.
NORTHERN LOWER LOOKS MUCH MORE PALTRY AS MOISTURE IS VERY THIN AND
OVERLAKE INSTABILITY IS EVEN WORSE (DELTA T VALUES UP AROUND 12C).
THAT SETUP SHOULD GIVE US PLENTY OF LAKE STRATUS...AND MAYBE A FEW
LIGHT SNOW SHOWERS...BUT PROBABLY MORE LIKE JUST SOME FLURRIES...
WITH THOSE LIKELY TO END THROUGH THE AFTERNOON AS MOISTURE FURTHER
THINS TO BELOW 900MB. HIGHS DEFINITELY A BIT CLOSER TO NORMAL BUT
STILL ABOVE...WITH READINGS MAINLY IN THE 32-38F RANGE.
TONIGHT LOOKS EVEN MORE QUIET AS THE WEAK SURFACE LOW PROGRESSES
TOWARD JAMES BAY...WHILE STRONGER LOW PRESSURE SLIDES THROUGH THE
OHIO VALLEY. THIS WILL ALLOW LOW LEVEL RIDGING TO BUILD INTO
NORTHERN MICHIGAN THROUGH THE NIGHT. WEAKENING GRADIENT SHOULD ALLOW
FOR SOME LAND BREEZE DEVELOPMENT...THEORETICALLY HELPING PUSH SOME
OF THE LAKE STRATUS CLOSER TO THE COASTS. HOWEVER...DEGREE OF
CLEARING REMAINS TO BE SEEN...AND NOT OVERLY ENTHUSIASTIC GIVEN SUCH
WIDESPREAD STRATUS SPREAD WELL UPSTREAM THROUGH THE NORTHERN
PLAINS/UPPER MIDWEST. DON`T FORESEE MUCH IN THE WAY OF ANY LINGERING
LAKE SNOW SHOWERS AS MOISTURE IS EVEN MORE THIN...BUT SUPPOSE A
ROGUE FLURRY IS POSSIBLE. OVERNIGHT LOWS WILL BE TIED TO DEGREE OF
CLEARING...BUT GIVEN OUR RECENT HISTORY AND STRONGER LIKELIHOOD FOR
CLOUDS TO PREVAIL...FEEL WARMER IS PROBABLY BETTER...AND WILL SIDE
WITH READINGS MAINLY IN THE UPPER HALF OF THE 20S TO LOWER 30S.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 315 AM EST MON DEC 17 2012
MILD AND RELATIVELY UNEVENTFUL WX WILL HOLD INTO WEDNESDAY. A
VARIETY OF OPTIONS ARE POSSIBLE AFTER THAT...THOUGH /UNEVENTFUL/
DOES NOT APPEAR TO BE ONE OF THEM. A WEAK N-S ORIENTED RIDGE AXIS
WILL BE OVER LOWER MI EARLY TUESDAY...TEMPORARILY DISLODGED BY A
VERY WEAK SURFACE WAVE TRANSITING FAR SOUTHERN LOWER MI IN THE
EVENING. SMALL PRECIP CHANCES MAY BE IN THE OFFING TUE-WED...BUT THE
MAIN SHOW WILL CLEARLY OCCUR AFTER THAT.
TUESDAY...850MB THERMAL TROF WILL BE DISPLACED EAST ACROSS LAKE
HURON DURING THE DAY...ALLOWING FOR A 2-3C RECOVERY TO -4 TO -7C.
THE STRONGEST WARM ADVECTION/ISENTROPIC ASCENT WILL FOCUS JUST TO
OUR SW...MOVING TOWARD SOUTHERN LAKE MI IN THE AFTERNOON. THIS IS IN
ADVANCE OF A 1004MB LOW MOVING EAST FROM CENTRAL IOWA TO NORTHERN
IL. FGEN FORCING WILL CONTRIBUTE TO A BAND OF MOISTENING ALOFT THAT
EVENTUALLY REACHES NE WI...CENTRAL AND SOUTHERN LOWER MI LATE. DRIER
AIR BELOW 800MB WILL BE MORE STUBBORN TO DISLODGE...BUT MODEL
SOUNDINGS ARE MORE OPTIMISTIC IN PROGGING PRECIP DOWN TO THE SURFACE
BY LATE AFTERNOON/EARLY EVENING. SO EARLIER ADDITION OF CHANCE POPS
TO PARTS OF NW LOWER MI STILL LOOKS VERY REASONABLE. WILL REMOVE A
MENTION OF MIX OVER THE HIGHER TERRAIN (CAD AREA)...WHERE SNOW
SHOULD PREVAIL IF PRECIP DEVELOPS. CLOSER TO LAKE MI (MBL/FKS)...A
RA/SN MENTION IS GOOD. PLENTY OF CLOUDS FOR MOST...COULD BE SOME
THIN SPOTS EARLY IN NE LOWER BEFORE MID/HIGH CLOUDS THICKEN. MAX
TEMPS IN THE 30S.
TUE NIGHT/WEDNESDAY...WARM ADVECTION/FGEN BAND OF MID-LEVEL MOISTURE
WILL CONTINUE TO LIFT ACROSS THE FORECAST AREA TUE NIGHT.
HOWEVER...LIFT WILL WEAKEN WITH TIME...ESPECIALLY OVERNIGHT...AS THE
WEAK SURFACE LOW REACHES LAKE ERIE AND FILLS. SMALL CHANCE POPS ARE
STILL REASONABLE FOR MUCH OF NORTHERN LOWER MI TUE EVENING (STILL
HOLDING ONTO A MIX IN COASTAL AREAS)...BUT SLIGHT CHANCE OR LESS
WILL SUFFICE BY THE TIME THE BAND LIFTS ACROSS EASTERN UPPER/FAR NE
LOWER MI OVERNIGHT. STRATUS SHOULD BE CONSIDERABLE BEHIND THE
DEPARTING BAND...BUT THERE MAY SOME BREAKS IN THE FAR SE. HIGH
PRESSURE MAKES A BRIEF RETURN WED MORNING...THEN SHUNTS EAST AS LOW
PRESSURE DEEPENS IN OK. PRECIP MAY START TO BREAK OUT IN
IOWA/NORTHERN IL DURING THE DAY...BUT NOT THIS FAR NE. IF WE GET
LUCKY...WE COULD SEE SOME BRIEF PERIODS OF SUN AS LOW LEVEL MOISTURE
GETS INCREASINGLY THIN...BUT MID/HIGH CLOUD WILL BE ON THE INCREASE
LATE.
MIN TEMPS ABOVE GUIDANCE GIVEN ABUNDANT CLOUDS...MID 20S TO LOWER
30S. MAX TEMPS MID 30S TO NEAR 40F.
REST OF THE FORECAST...YESTERDAYS TIGHTLY-CLUSTERED SOLUTIONS WERE
DESTINED NOT TO REPEAT. THE DAY SHIFT NOTED A TREND TOWARD A LESS
AMPLIFIED AND MORE SOUTHERLY TRACK FOR THE LOW FORECAST TO CROSS THE
LAKES REGION LATE THURSDAY. TONIGHT...WE/VE MOVED BACK TO A MEAN
THAT LOOKS SIMILAR TO LAST NIGHT...THOUGH WITH MORE IN THE WAY OF
MODEL SPREAD. THEY (AND I) CONTINUE TO STRUGGLE A BIT WITH COMPETING
ELEMENTS. WE HAVE A TON OF ENERGY POURING INTO THE PAC COAST TO PUSH
THINGS ALONG...AND A WEAK BLOCKING RIDGE OVER FAR EASTERN CANADA.
THE BLOCK IS NOT IMPRESSIVE AND WILL BE DISLODGED...BUT HOW QUICKLY?
THE INCOMING UPPER TROF TAKES ON A NEGATIVE TILT...BUT OVERALL THE
PATTERN IS QUITE PROGRESSIVE AND NOT HIGHLY AMPLIFIED. HOW MUCH WILL
THE SYSTEM WRAP UP...SLOW DOWN...AND GET TUGGED NW (IF AT ALL)?
THE NAM AND DGEX REPRESENT DEEPER AND MORE NORTHERLY TRACKS THAT
WOULD BE MORE RAIN AND LESS SNOW FOR US. 00Z ECMWF OFFERS THE MOST
SOUTHERLY...SNOWIEST SOLUTION. GFS/GEM ARE SOMEWHERE IN BETWEEN...
THOUGH WITH THE GEM SLOWER THAN THE REST OF THE MODELS. SOME SORT OF
GEM/GFS/ECMWF MISH-MASH IS MOST APPROPRIATE...AS WE STILL HAVE TIME
TO SEE HOW THE DETAILS FALL OUT.
PRECIP SHOULD ARRIVE IN SW SECTIONS OVERNIGHT WED NIGHT...MAINLY AS
SNOW. A TRACK ACROSS CENTRAL LOWER MI LATE THURSDAY WILL OPEN UP AT
LEAST THE SE HALF OF THE FORECAST AREA TO MIX WITH/TURN TO RAIN.
WINDY/SNOWY CONDITIONS LATE THURSDAY NIGHT INTO FRIDAY AS SYSTEM
DEPARTS. POTENTIAL FOR SUBSTANTIAL LAKE ENHANCEMENT...BUT VERY
DIFFICULT TO ANSWER THE FETCH QUESTION YET GIVEN MODEL DIFFS. WILL
TRY TO ADD A FEW DETAILS TO THE HAZ WX OUTLOOK. COLDER TEMPS (NEAR
CLIMO) OVER THE WEEKEND...WITH DECREASING CHANCES FOR LAKE EFFECT AS
SURFACE RIDGING TRIES TO EDGE EAST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1237 PM EST MON DEC 17 2012
PERSISTENT MVFR/LOW END VFR OVERCAST EXPECTED TO CONTINUE THROUGH
THE TAF CYCLE AS ABUNDANT LOW LEVEL MOISTURE REMAINS LOCKED IN PLACE.
SOME LIGHT RAIN SHOWERS EXPECTED VC KTVC AND KPLN FOR A FEW MORE
HOURS BEFORE THEY DISSIPATE. LIGHT WINDS WILL ALSO CONTINUE
THROUGH THE DURATION.
&&
.MARINE...
ISSUED AT 315 AM EST MON DEC 17 2012
LIGHT WINDS AND LOW WAVES ARE EXPECTED AS WE HEAD INTO THE MID WEEK
PERIOD...AS WEAK LOW PRESSURE DRIFTS OUT OF THE REGION TODAY...ONLY
TO BE REPLACED BY HIGH PRESSURE THROUGH AT LEAST WEDNESDAY EVENING.
THE ONE EXCEPTION WILL BE TODAY...AS SLIGHTLY STRONGER WINDS WILL BE
FOUND ACROSS THE WATERS (STILL LESS THAN 20 KNOTS) AS COOLER AIR
FILTERS INTO THE REGION. AFTER THAT...STRONG LOW PRESSURE IS
EXPECTED TO TRACK THROUGH THE REGION WEDNESDAY NIGHT THROUGH
FRIDAY...USHERING IN A PERIOD OF MUCH STRONGER WINDS...WITH GALE
FORCE GUSTS VERY POSSIBLE. WIDESPREAD RAIN AND/OR SNOW IS ALSO
EXPECTED TO ACCOMPANY THIS SYSTEM...WITH LAKE EFFECT SNOW SHOWERS
AND CONTINUED GUSTY CONDITIONS LIKELY FOR THE WEEKEND.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...NONE.
LS...NONE.
&&
$$
UPDATE...MB
SYNOPSIS...JZ
SHORT TERM...LAWRENCE
LONG TERM...JZ
AVIATION...MB
MARINE...LAWRENCE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1237 PM EST MON DEC 17 2012
.UPDATE...
ISSUED AT 1120 AM EST MON DEC 17 2012
SHORTWAVE THAT BROUGHT LGT SNOW/FLURRIES TO NORTHERN CWA EARLIER
THIS MORNING IS SLIDING OVR FAR EASTERN LK SUPERIOR NEAR WHITEFISH
POINT/SAULT STE MARIE. FEATURE PRETTY IMPRESSIVE LOOKING ON WV WITH
TIGHT SPIN NOTED. CANADIAN RADAR/SFC OBS SHOWING WIDESPREAD LGT
PRECIP FM ERY TO ANJ. VSBY AT ERY NOW DOWN TO 4SM...INDICATING SNOW
IS INTENSIFYING SOME. COULD SEE ADDITIONAL SNOW ACCUMS UP TO 1 INCH
THROUGH EARLY AFTN...BUT WOULD BE PRETTY LOCALIZED OVR NORTHERN LUCE
COUNTY. SEEMS LIKE RAIN/SNOW MIX SEEN AT CYAM/ANJ THIS MORNING IS
STAYING JUST TO NORTH OF ERY TOWARD WHITEFISH POINT. ELSEWHERE JUST A
FEW FLURRIES/SNOW SHOWERS ARE ONGOING OVR NCNTRL CWA AND MAYBE KEWEENAW
TOO...THOUGH CMX HAS NOT REPORTED ANYTHING IN A WHILE. GOING POPS
WERE IN FINE SHAPE...LITTLE CHANGES MADE THERE. LINGERING LGT SNOW
SHOULD BE EXITING THE EASTERN CWA THIS EVENING.
BASED ON 12Z SOUNDING FM GRB SHOWING MOISTURE UP TO 875MB TRAPPED
BENEATH INCREASING SUBSIDENCE INVERSION...LOW SUN ANGLE IN MID
DECEMBER AND LACK OF DRY AIR ADVECTION INTO REGION...HAVE KEPT SKIES
CLOUDY THROUGH THE DAY AND EVEN INTO TONIGHT. RAP ONLY MODEL THAT
HAD GOOD HANDLE ON DEPTH OF MOISTURE. NAM SOUNDING AT GRB FOR 12Z
SHOWED THIN LAYER OF MOISTURE AT 950MB WITH DRYING ABOVE...WHICH WAS
NOT EVEN CLOSE. USING THE RAP AND EXTRAPOLATION OF THAT MODEL...HAVE
CARRIED CLOUDY SKIES THROUGH TONIGHT. OVERALL IMPACT TO FORECAST IS
NOT HUGE. TEMPS WILL REMAIN FAIRLY STEADY TODAY /MID 20S WEST TO MID
30S EAST/ AND MIN TEMPS TONIGHT MAY JUST STAY IN THE 20S DUE TO THE
EXTENSIVE CLOUDS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM EST MON DEC 17 2012
LOW PRESSURE RESTING OVER THE UPPER GREAT LAKES EARLY THIS MORNING
WILL CONTINUE TO MOVE NORTHEASTWARD INTO THE NEW ENGLAND STATES AND
NORTHERN ONTARIO. AS IT DOES A WEAK RIDGE OF HIGH PRESSURE ALOFT AND
AT THE SURFACE WILL SLIDE INTO THE AREA...AND REMAIN THROUGH LATE
MONDAY NIGHT. THAT BEING SAID...WITH LACK OF ANY MENTIONABLE SYSTEMS
IN THE AREA...THE WEATHER WILL BE FAIRLY QUIET FOR THE START OF THE
WORK WEEK.
BEHIND THE EXITING SHORTWAVE...MOISTURE WILL BE SLOW TO EXIT...AS
925-850MB DEWPOINT DEPRESSIONS ARE AROUND 1-2C THROUGH MONDAY
MORNING ACROSS MUCH OF THE CWA. COLD AIR WILL FILTER INTO THE
WESTERN CWA ON WESTERLY TO NORTHWESTERLY WINDS THROUGHOUT THE DAY
TODAY...EVENTUALLY REACHING -8C TO -9C. GIVEN THE LINGERING MOISTURE
AND LAKE TEMP-850MB TEMP DIFFERENCE OF AROUND 12C-14C THINKING
WESTERN UPPER MICHIGAN AND FAR EASTERN UPPER MICHIGAN WILL SEE SOME
LAKE EFFECT SNOW SHOWERS. SNOW SHOWERS WILL SLOWLY BECOME MORE
ISOLATED LATE MONDAY AFTERNOON INTO MONDAY EVENING AS THE DRIEST AIR
AND ANTICYCLONIC FLOW SETTLE INTO THE REGION. THINKING THERE COULD
BE SOME BREAKS IN CLOUD COVER MONDAY AFTERNOON SOUTH CENTRAL AND
WEST WITH THIS DRYING...BUT EXPECT AREAS NEAR LAKE
SUPERIOR...ESPECIALLY FURTHEST EAST...WILL STAY CLOUDY. ANY BROKEN
SPOTS WILL QUICKLY DIMINISH LATE MONDAY NIGHT AS ANOTHER SHORTWAVE
APPROACHES THE REGION AND WINDS BECOME MORE SOUTHERLY.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 406 AM EST MON DEC 17 2012
A SURFACE LOW IS EXPECTED TO BE ALONG THE U.S./CANADIAN BORDER NEAR
NORTHWEST ND AT THE START OF THE PERIOD. A WEAK SURFACE TROUGH
STRETCHING ESE FROM THIS LOW WILL MOVE THROUGH THE CWA TUESDAY
AFTERNOON/EVENING...BUT DECAYS AS THE UPPER ENERGY WEAKENS AND
SHIFTS TO THE NORTHEAST. MEANWHILE...ANOTHER WEAK LOW OVER THE
CENTRAL MISSISSIPPI VALLEY WILL SHIFT EAST TOWARDS SOUTHERN LAKE
MICHIGAN AND DISSIPATE. WITH THE BULK OF THE ENERGY SPLITTING THE
CWA...DON/T EXPECT MUCH CHANCE FOR PRECIPITATION AND FEEL THAT THE
GOING SLIGHT CHANCES ARE REASONABLE FOR THE BROAD/WEAK WAA AND WILL
FOLLOW SUIT. ONCE THIS SHIFTS TO THE NORTHEAST TUESDAY NIGHT INTO
WEDNESDAY MORNING...AREA WILL BE BETWEEN SYSTEMS AND SHOULD LEAD TO
A QUIET DAY ON WEDNESDAY. WITH THE COLD AIR LOCKED WELL TO THE NORTH
OF THE AREA...ABOVE NORMAL TEMPERATURES WILL CONTINUE TUESDAY AND
WEDNESDAY.
ATTENTION THEN TURNS TO THE STRONG LOW PRESSURE SYSTEM TO AFFECT THE
GREAT LAKES REGION THURSDAY AND THURSDAY NIGHT...WITH THE STRONG
N-NW FLOW LAKE EFFECT INTO THE WEEKEND. WAVE CURRENTLY SOUTH OF
ALASKA AND OVER THE PACIFIC WILL BE THE ONE TO WATCH AS IT MOVES
INTO THE WESTERN CONUS ON TUESDAY AND THEN INTO THE CENTRAL PLAINS
ON WEDNESDAY NIGHT. AS THE TROUGH EXITS INTO THE GREAT LAKES
REGION...IT IS EXPECTED TO BECOME NEGATIVELY TILTED AND SEND A LOW
THROUGH THE CENTRAL GREAT LAKES. WHERE THIS LOW TRACKS WILL
DETERMINE MUCH OF THE SNOWFALL POTENTIAL FOR UPPER MICHIGAN ON
THURSDAY AND THURSDAY NIGHT.
ALL OF THE MODELS SEEM TO HAVE THE SAME IDEA WITH THE LOW
DEVELOPING AND MOVING THROUGH THE CENTRAL GREAT LAKES...IT/S JUST
PINNING DOWN THE EXACT TRACK THAT THEY ARE STRUGGLING WITH. ECMWF
SEEMS TO BE THE MOST CONSISTENT OVER THE LAST 4-5 RUNS...WHILE THE
GEM/GFS/UKMET HAVE BEEN BOUNCING AROUND IN BOTH SPEED AND
LOCATION. THE ECMWF TRACK...WHICH HAS STRONG SUPPORT FROM IT/S
ENSEMBLE MEMBERS AND ALSO THE RECENT GEM AND GEM ENSEMBLE MEAN
TRACKS THE LOW THROUGH SOUTHEAST LOWER MICHIGAN THURSDAY AFTERNOON
AND EVENING. MEANWHILE...THE LATEST GFS TRACKS IT ACROSS NORTHERN
LOWER MICHIGAN AND HAS SUPPORT OF IT/S ENSEMBLE MEMBERS AND THE
UKMET. WITH THE SYSTEM OVER THE OCEAN AND NEAR ALASKA...WANT TO
TREND TOWARDS THE ECMWF DUE TO CONSISTENCY AND IT/S SUPERIOR
HANDLING/INITIALIZING OF SATELLITE DATA IN THAT AREA. IN
ADDITION...WITH THE TROUGH NOT DIGGING TOO DEEP AND WITH LIMITED
COLD AIR SPILLING SOUTH WITH THE TROUGH...WONDER IF THE SOUTHERN
SOLN WILL PAN OUT COMPARED TO MORE COLD AIR SHARPENING THE UPPER
TROUGH IN A MORE TRADITIONAL WINTER WEATHER SITUATION. BUT WITH THE
POTENTIAL HIGH IMPACT...FEEL THAT FOLLOWING A GENERAL CONSENSUS
FROM THE GFS/ECMWF/GEM IS THE WAY TO GO AT THIS POINT.
THIS GENERAL CONSENSUS WOULD PUSH AN INITIAL WAVE OF WAA
PRECIPITATION ACROSS THE EASTERN HALF OF THE CWA LATE WEDNESDAY
NIGHT AND INTO THURSDAY AND THEN TRANSITION TO LAKE ENHANCE
SNOW NEAR LAKE SUPERIOR WHILE THE TROWAL TRACKS ACROSS NORTHERN
LAKE MICHIGAN OR NORTHWEST LOWER MICHIGAN. AS FOR THE SYNOPTIC
PRECIPITATION...OVERALL CONSENSUS WOULD HAVE THE HIGHEST AMOUNTS
NEAR THE LAKE MICHIGAN SHORELINE AND GENERALLY HIGH END ADVISORY
SNOWFALL AMOUNTS EAST OF A LINE FROM ISHPEMING TO IRON MOUNTAIN.
WHEN FACTORING IN THE WIND AND SOME BLOWING SNOW COULD SEE SOME
HIGHER HEADLINES. THEREFORE...WILL CONTINUE TO MENTION IN THE HWO
AND TOP NEWS STORIES.
THE OTHER FACTOR WITH THIS SYSTEM IS LAKE ENHANCEMENT OFF LAKE
SUPERIOR AS WINDS TURN TO THE NORTH ON THURSDAY AND THEN TO THE
NORTHWEST THURSDAY NIGHT. BEST DEEP MOISTURE FOR LAKE ENHANCEMENT
LOOKS TO BE FROM MARQUETTE COUNTY AND EASTWARD ON THURSDAY AFTERNOON
INTO THURSDAY NIGHT. HAVEN/T HAD ANY GOOD CLEAR DAYS TO GET A RECENT
SATELLITE ESTIMATE OF THE LAKE SUPERIOR TEMPS...BUT GLERL ANALYSIS
INDICATES VALUES IN THE 3-4C RANGE WHICH WOULD PRODUCE DELTA-T
VALUES OF 10-12. WITH THE WIND DIRECTIONS THURSDAY AFTERNOON
INTO THURSDAY NIGHT...THINK THE BEST LOCATIONS FOR LAKE ENHANCEMENT
WILL BE OVER MARQUETTE/ALGER COUNTIES WITH THE NORTHERLY WINDS
TAPPING INTO THE LONGEST FETCH AND SOME ENHANCED CONVERGENCE WITH
THE BACKING CYCLONIC FLOW THROUGH THURSDAY NIGHT. AS HAS BEEN THE
CASE THIS WINTER...THE LIMITED AMOUNT OF COLD AIR BEHIND THE
SYSTEM LEADS TO UNCERTAINTY IN THE AMOUNT OF LAKE ENHANCEMENT AND
RESULTING SNOWFALL AMOUNTS. FARTHER WEST THE SNOW POTENTIAL IS UP IN
THE AIR...AS IT WILL LARGELY DEPEND ON THE LOW TRACK TO PROVIDE
ENOUGH MOISTURE FOR LAKE ENHANCE/EFFECT SNOW. THIS LAKE ENHANCE SNOW
SHOULD CONTINUE INTO FRIDAY ALTHOUGH IT IS EXPECTED TO DIMINISH INTO
THE AFTERNOON AS THE DEEPER MOISTURE DEPARTS AND AN UPPER RIDGE
BEGINS TO BUILD INTO THE AREA.
AFTER THE SYSTEM SHIFTS TO THE NORTHEAST ON FRIDAY...EXPECT THE
AREA TO BE UNDER PERSISTANT N-NW FLOW INTO THE WEEKEND. THIS IS DUE
TO THE UPPER TROUGH BECOMING CLOSED OFF AND STALLING OVER THE NEW
ENGLAND STATES IN RESPONSE TO AN UPSTREAM UPPER LOW SE OF
GREENLAND. THIS WILL PUT THE CWA BETWEEN THE EXITING SURFACE LOW
AND HIGH PRESSURE CENTERED OVER LAKE WINNIPEG. LES LOCATIONS WILL
DEPEND ON HOW THE PRESSURE FIELD SETS UP...BUT AT THIS POINT IT
LOOKS LIKE NORTHERLY WIND LOCATIONS ON THURSDAY NIGHT WITH THE LAKE
ENHANCEMENT...THEN TRANSFERRING TO NORTHWEST FLOW LAKE EFFECT ON
FRIDAY AND CONTINUING INTO THE WEEKEND. INITIAL LOOK WOULD SUPPORT
THE POTENTIAL FOR PERSISTENT LAKE EFFECT DURING THIS PERIOD...BUT
THERE ARE SEVERAL FACTORS THAT ARE LIKELY TO LIMIT THE INTENSITY.
THE FIRST LIMITING FACTOR IS THE LIMITED AMOUNT OF COLD AIR...WHICH
THE BUILDING RIDGE ON FRIDAY AFTERNOON THROUGH SATURDAY MORNING
WORKS TO PUT DELTA-T VALUES IN THE 9-13 RANGE. SECOND...THE
SUBSIDENCE INVERSION TAKES HOLD ON FRIDAY NIGHT /INVERSION HEIGHTS
FALL TO 4KFT/ WITH THE SYSTEM SHIFTING TO THE EAST. THIS SHOULD
GREATLY DIMINISH LES INTENSITY THROUGH THE NIGHT AND INTO SATURDAY.
AND THIRD IS THAT THE STRONG WINDS ON FRIDAY INTO FRIDAY NIGHT WILL
LEAD TO LESS RESIDENCE TIME OVER LAKE SUPERIOR AND ALSO CAUSE
FRACTURING OF ANY LARGER DENDRITIC SNOWFLAKES...ALTHOUGH THERE MAY
NOT BE TOO MANY BASED OFF BUFKIT SOUNDINGS. THEREFORE...HAVE
DIMINISHED THE POPS THROUGH THE DAY FRIDAY AND INTO SATURDAY MORNING
BEFORE SECOND WAVE MOVES THROUGH SAT AFTERNOON INTO SAT
NIGHT...PROVIDING SOME ADDITIONAL DEEPER MOISTURE. THE AMOUNT OF
MOISTURE AND TIMING OF THE WAVE DIFFERS IN THE MODELS...SO WILL JUST
KEEP LOW CHANCE POPS IN THE NORTHWEST WIND FAVORED LOCATIONS INTO
SUNDAY.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1233 PM EST MON DEC 17 2012
EXPECT LOW MVFR CLOUD DECK TO PERSIST THROUGH THE REST OF THE DAY
AS MOISTURE THROUGH 3-4KFT IS TRAPPED BENEATH SUBSIDENCE INVERSION.
LIMITED DRY AIR ADVECTION AND LOW SUN ANGLE FOR MID DECEMBER WILL NOT
HELP MIX OUT THE CLOUDS TODAY AS WELL. CIGS AT ALL SITES SHOULD
TRANSITION TO AN OVC VFR MID CLOUD DECK LATER TONIGHT INTO TUESDAY AS
WINDS BECOME MORE SOUTHWEST TO SOUTH HELPING TO SCOUR OUT LOW-LEVEL
MOISTURE.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 406 AM EST MON DEC 17 2012
AS HIGH PRESSURE SHIFTS INTO THE AREA TODAY...WEST TO NORTHWEST
WINDS OF 15 TO 25 KTS WILL DIE DOWN TO GENERALLY LESS THAN 15 KTS BY
LATE TONIGHT.
MAIN TIME OF CONCERN FOR THE MARINE FORECAST IS DURING THE END OF
THE WEEK AS A LOW PRESSURE SYSTEM MOVES THROUGH THE CENTRAL GREAT
LAKES. SEEMS VERY LIKELY THAT NORTH TO NORTHWEST GALES OF
35-40KTS WILL OCCUR OVER MUCH OF THE LAKE THURSDAY INTO FRIDAY. THE
NORTHWEST WINDS WILL REMAIN IN PLACE INTO THE WEEKEND...ALTHOUGH T
THEY SHOULD ONLY BE 20-30KTS...AS LAKE SUPERIOR IS SITUATED BETWEEN
THE LOW OVER THE NEW ENGLAND STATES AND HIGH PRESSURE OVER LAKE
WINNIPEG.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...JLA
SHORT TERM...MCD
LONG TERM...SRF
AVIATION...JLA
MARINE...MCD/SRF
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1129 AM EST MON DEC 17 2012
.UPDATE...
ISSUED AT 1120 AM EST MON DEC 17 2012
SHORTWAVE THAT BROUGHT LGT SNOW/FLURRIES TO NORTHERN CWA EARLIER
THIS MORNING IS SLIDING OVR FAR EASTERN LK SUPERIOR NEAR WHITEFISH
POINT/SAULT STE MARIE. FEATURE PRETTY IMPRESSIVE LOOKING ON WV WITH
TIGHT SPIN NOTED. CANADIAN RADAR/SFC OBS SHOWING WIDESPREAD LGT
PRECIP FM ERY TO ANJ. VSBY AT ERY NOW DOWN TO 4SM...INDICATING SNOW
IS INTENSIFYING SOME. COULD SEE ADDITIONAL SNOW ACCUMS UP TO 1 INCH
THROUGH EARLY AFTN...BUT WOULD BE PRETTY LOCALIZED OVR NORTHERN LUCE
COUNTY. SEEMS LIKE RAIN/SNOW MIX SEEN AT CYAM/ANJ THIS MORNING IS
STAYING JUST TO NORTH OF ERY TOWARD WHITEFISH POINT. ELSEWHERE JUST A
FEW FLURRIES/SNOW SHOWERS ARE ONGOING OVR NCNTRL CWA AND MAYBE KEWEENAW
TOO...THOUGH CMX HAS NOT REPORTED ANYTHING IN A WHILE. GOING POPS
WERE IN FINE SHAPE...LITTLE CHANGES MADE THERE. LINGERING LGT SNOW
SHOULD BE EXITING THE EASTERN CWA THIS EVENING.
BASED ON 12Z SOUNDING FM GRB SHOWING MOISTURE UP TO 875MB TRAPPED
BENEATH INCREASING SUBSIDENCE INVERSION...LOW SUN ANGLE IN MID
DECEMBER AND LACK OF DRY AIR ADVECTION INTO REGION...HAVE KEPT SKIES
CLOUDY THROUGH THE DAY AND EVEN INTO TONIGHT. RAP ONLY MODEL THAT
HAD GOOD HANDLE ON DEPTH OF MOISTURE. NAM SOUNDING AT GRB FOR 12Z
SHOWED THIN LAYER OF MOISTURE AT 950MB WITH DRYING ABOVE...WHICH WAS
NOT EVEN CLOSE. USING THE RAP AND EXTRAPOLATION OF THAT MODEL...HAVE
CARRIED CLOUDY SKIES THROUGH TONIGHT. OVERALL IMPACT TO FORECAST IS
NOT HUGE. TEMPS WILL REMAIN FAIRLY STEADY TODAY /MID 20S WEST TO MID
30S EAST/ AND MIN TEMPS TONIGHT MAY JUST STAY IN THE 20S DUE TO THE
EXTENSIVE CLOUDS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 406 AM EST MON DEC 17 2012
LOW PRESSURE RESTING OVER THE UPPER GREAT LAKES EARLY THIS MORNING
WILL CONTINUE TO MOVE NORTHEASTWARD INTO THE NEW ENGLAND STATES AND
NORTHERN ONTARIO. AS IT DOES A WEAK RIDGE OF HIGH PRESSURE ALOFT AND
AT THE SURFACE WILL SLIDE INTO THE AREA...AND REMAIN THROUGH LATE
MONDAY NIGHT. THAT BEING SAID...WITH LACK OF ANY MENTIONABLE SYSTEMS
IN THE AREA...THE WEATHER WILL BE FAIRLY QUIET FOR THE START OF THE
WORK WEEK.
BEHIND THE EXITING SHORTWAVE...MOISTURE WILL BE SLOW TO EXIT...AS
925-850MB DEWPOINT DEPRESSIONS ARE AROUND 1-2C THROUGH MONDAY
MORNING ACROSS MUCH OF THE CWA. COLD AIR WILL FILTER INTO THE
WESTERN CWA ON WESTERLY TO NORTHWESTERLY WINDS THROUGHOUT THE DAY
TODAY...EVENTUALLY REACHING -8C TO -9C. GIVEN THE LINGERING MOISTURE
AND LAKE TEMP-850MB TEMP DIFFERENCE OF AROUND 12C-14C THINKING
WESTERN UPPER MICHIGAN AND FAR EASTERN UPPER MICHIGAN WILL SEE SOME
LAKE EFFECT SNOW SHOWERS. SNOW SHOWERS WILL SLOWLY BECOME MORE
ISOLATED LATE MONDAY AFTERNOON INTO MONDAY EVENING AS THE DRIEST AIR
AND ANTICYCLONIC FLOW SETTLE INTO THE REGION. THINKING THERE COULD
BE SOME BREAKS IN CLOUD COVER MONDAY AFTERNOON SOUTH CENTRAL AND
WEST WITH THIS DRYING...BUT EXPECT AREAS NEAR LAKE
SUPERIOR...ESPECIALLY FURTHEST EAST...WILL STAY CLOUDY. ANY BROKEN
SPOTS WILL QUICKLY DIMINISH LATE MONDAY NIGHT AS ANOTHER SHORTWAVE
APPROACHES THE REGION AND WINDS BECOME MORE SOUTHERLY.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 406 AM EST MON DEC 17 2012
A SURFACE LOW IS EXPECTED TO BE ALONG THE U.S./CANADIAN BORDER NEAR
NORTHWEST ND AT THE START OF THE PERIOD. A WEAK SURFACE TROUGH
STRETCHING ESE FROM THIS LOW WILL MOVE THROUGH THE CWA TUESDAY
AFTERNOON/EVENING...BUT DECAYS AS THE UPPER ENERGY WEAKENS AND
SHIFTS TO THE NORTHEAST. MEANWHILE...ANOTHER WEAK LOW OVER THE
CENTRAL MISSISSIPPI VALLEY WILL SHIFT EAST TOWARDS SOUTHERN LAKE
MICHIGAN AND DISSIPATE. WITH THE BULK OF THE ENERGY SPLITTING THE
CWA...DON/T EXPECT MUCH CHANCE FOR PRECIPITATION AND FEEL THAT THE
GOING SLIGHT CHANCES ARE REASONABLE FOR THE BROAD/WEAK WAA AND WILL
FOLLOW SUIT. ONCE THIS SHIFTS TO THE NORTHEAST TUESDAY NIGHT INTO
WEDNESDAY MORNING...AREA WILL BE BETWEEN SYSTEMS AND SHOULD LEAD TO
A QUIET DAY ON WEDNESDAY. WITH THE COLD AIR LOCKED WELL TO THE NORTH
OF THE AREA...ABOVE NORMAL TEMPERATURES WILL CONTINUE TUESDAY AND
WEDNESDAY.
ATTENTION THEN TURNS TO THE STRONG LOW PRESSURE SYSTEM TO AFFECT THE
GREAT LAKES REGION THURSDAY AND THURSDAY NIGHT...WITH THE STRONG
N-NW FLOW LAKE EFFECT INTO THE WEEKEND. WAVE CURRENTLY SOUTH OF
ALASKA AND OVER THE PACIFIC WILL BE THE ONE TO WATCH AS IT MOVES
INTO THE WESTERN CONUS ON TUESDAY AND THEN INTO THE CENTRAL PLAINS
ON WEDNESDAY NIGHT. AS THE TROUGH EXITS INTO THE GREAT LAKES
REGION...IT IS EXPECTED TO BECOME NEGATIVELY TILTED AND SEND A LOW
THROUGH THE CENTRAL GREAT LAKES. WHERE THIS LOW TRACKS WILL
DETERMINE MUCH OF THE SNOWFALL POTENTIAL FOR UPPER MICHIGAN ON
THURSDAY AND THURSDAY NIGHT.
ALL OF THE MODELS SEEM TO HAVE THE SAME IDEA WITH THE LOW
DEVELOPING AND MOVING THROUGH THE CENTRAL GREAT LAKES...IT/S JUST
PINNING DOWN THE EXACT TRACK THAT THEY ARE STRUGGLING WITH. ECMWF
SEEMS TO BE THE MOST CONSISTENT OVER THE LAST 4-5 RUNS...WHILE THE
GEM/GFS/UKMET HAVE BEEN BOUNCING AROUND IN BOTH SPEED AND
LOCATION. THE ECMWF TRACK...WHICH HAS STRONG SUPPORT FROM IT/S
ENSEMBLE MEMBERS AND ALSO THE RECENT GEM AND GEM ENSEMBLE MEAN
TRACKS THE LOW THROUGH SOUTHEAST LOWER MICHIGAN THURSDAY AFTERNOON
AND EVENING. MEANWHILE...THE LATEST GFS TRACKS IT ACROSS NORTHERN
LOWER MICHIGAN AND HAS SUPPORT OF IT/S ENSEMBLE MEMBERS AND THE
UKMET. WITH THE SYSTEM OVER THE OCEAN AND NEAR ALASKA...WANT TO
TREND TOWARDS THE ECMWF DUE TO CONSISTENCY AND IT/S SUPERIOR
HANDLING/INITIALIZING OF SATELLITE DATA IN THAT AREA. IN
ADDITION...WITH THE TROUGH NOT DIGGING TOO DEEP AND WITH LIMITED
COLD AIR SPILLING SOUTH WITH THE TROUGH...WONDER IF THE SOUTHERN
SOLN WILL PAN OUT COMPARED TO MORE COLD AIR SHARPENING THE UPPER
TROUGH IN A MORE TRADITIONAL WINTER WEATHER SITUATION. BUT WITH THE
POTENTIAL HIGH IMPACT...FEEL THAT FOLLOWING A GENERAL CONSENSUS
FROM THE GFS/ECMWF/GEM IS THE WAY TO GO AT THIS POINT.
THIS GENERAL CONSENSUS WOULD PUSH AN INITIAL WAVE OF WAA
PRECIPITATION ACROSS THE EASTERN HALF OF THE CWA LATE WEDNESDAY
NIGHT AND INTO THURSDAY AND THEN TRANSITION TO LAKE ENHANCE
SNOW NEAR LAKE SUPERIOR WHILE THE TROWAL TRACKS ACROSS NORTHERN
LAKE MICHIGAN OR NORTHWEST LOWER MICHIGAN. AS FOR THE SYNOPTIC
PRECIPITATION...OVERALL CONSENSUS WOULD HAVE THE HIGHEST AMOUNTS
NEAR THE LAKE MICHIGAN SHORELINE AND GENERALLY HIGH END ADVISORY
SNOWFALL AMOUNTS EAST OF A LINE FROM ISHPEMING TO IRON MOUNTAIN.
WHEN FACTORING IN THE WIND AND SOME BLOWING SNOW COULD SEE SOME
HIGHER HEADLINES. THEREFORE...WILL CONTINUE TO MENTION IN THE HWO
AND TOP NEWS STORIES.
THE OTHER FACTOR WITH THIS SYSTEM IS LAKE ENHANCEMENT OFF LAKE
SUPERIOR AS WINDS TURN TO THE NORTH ON THURSDAY AND THEN TO THE
NORTHWEST THURSDAY NIGHT. BEST DEEP MOISTURE FOR LAKE ENHANCEMENT
LOOKS TO BE FROM MARQUETTE COUNTY AND EASTWARD ON THURSDAY AFTERNOON
INTO THURSDAY NIGHT. HAVEN/T HAD ANY GOOD CLEAR DAYS TO GET A RECENT
SATELLITE ESTIMATE OF THE LAKE SUPERIOR TEMPS...BUT GLERL ANALYSIS
INDICATES VALUES IN THE 3-4C RANGE WHICH WOULD PRODUCE DELTA-T
VALUES OF 10-12. WITH THE WIND DIRECTIONS THURSDAY AFTERNOON
INTO THURSDAY NIGHT...THINK THE BEST LOCATIONS FOR LAKE ENHANCEMENT
WILL BE OVER MARQUETTE/ALGER COUNTIES WITH THE NORTHERLY WINDS
TAPPING INTO THE LONGEST FETCH AND SOME ENHANCED CONVERGENCE WITH
THE BACKING CYCLONIC FLOW THROUGH THURSDAY NIGHT. AS HAS BEEN THE
CASE THIS WINTER...THE LIMITED AMOUNT OF COLD AIR BEHIND THE
SYSTEM LEADS TO UNCERTAINTY IN THE AMOUNT OF LAKE ENHANCEMENT AND
RESULTING SNOWFALL AMOUNTS. FARTHER WEST THE SNOW POTENTIAL IS UP IN
THE AIR...AS IT WILL LARGELY DEPEND ON THE LOW TRACK TO PROVIDE
ENOUGH MOISTURE FOR LAKE ENHANCE/EFFECT SNOW. THIS LAKE ENHANCE SNOW
SHOULD CONTINUE INTO FRIDAY ALTHOUGH IT IS EXPECTED TO DIMINISH INTO
THE AFTERNOON AS THE DEEPER MOISTURE DEPARTS AND AN UPPER RIDGE
BEGINS TO BUILD INTO THE AREA.
AFTER THE SYSTEM SHIFTS TO THE NORTHEAST ON FRIDAY...EXPECT THE
AREA TO BE UNDER PERSISTANT N-NW FLOW INTO THE WEEKEND. THIS IS DUE
TO THE UPPER TROUGH BECOMING CLOSED OFF AND STALLING OVER THE NEW
ENGLAND STATES IN RESPONSE TO AN UPSTREAM UPPER LOW SE OF
GREENLAND. THIS WILL PUT THE CWA BETWEEN THE EXITING SURFACE LOW
AND HIGH PRESSURE CENTERED OVER LAKE WINNIPEG. LES LOCATIONS WILL
DEPEND ON HOW THE PRESSURE FIELD SETS UP...BUT AT THIS POINT IT
LOOKS LIKE NORTHERLY WIND LOCATIONS ON THURSDAY NIGHT WITH THE LAKE
ENHANCEMENT...THEN TRANSFERRING TO NORTHWEST FLOW LAKE EFFECT ON
FRIDAY AND CONTINUING INTO THE WEEKEND. INITIAL LOOK WOULD SUPPORT
THE POTENTIAL FOR PERSISTENT LAKE EFFECT DURING THIS PERIOD...BUT
THERE ARE SEVERAL FACTORS THAT ARE LIKELY TO LIMIT THE INTENSITY.
THE FIRST LIMITING FACTOR IS THE LIMITED AMOUNT OF COLD AIR...WHICH
THE BUILDING RIDGE ON FRIDAY AFTERNOON THROUGH SATURDAY MORNING
WORKS TO PUT DELTA-T VALUES IN THE 9-13 RANGE. SECOND...THE
SUBSIDENCE INVERSION TAKES HOLD ON FRIDAY NIGHT /INVERSION HEIGHTS
FALL TO 4KFT/ WITH THE SYSTEM SHIFTING TO THE EAST. THIS SHOULD
GREATLY DIMINISH LES INTENSITY THROUGH THE NIGHT AND INTO SATURDAY.
AND THIRD IS THAT THE STRONG WINDS ON FRIDAY INTO FRIDAY NIGHT WILL
LEAD TO LESS RESIDENCE TIME OVER LAKE SUPERIOR AND ALSO CAUSE
FRACTURING OF ANY LARGER DENDRITIC SNOWFLAKES...ALTHOUGH THERE MAY
NOT BE TOO MANY BASED OFF BUFKIT SOUNDINGS. THEREFORE...HAVE
DIMINISHED THE POPS THROUGH THE DAY FRIDAY AND INTO SATURDAY MORNING
BEFORE SECOND WAVE MOVES THROUGH SAT AFTERNOON INTO SAT
NIGHT...PROVIDING SOME ADDITIONAL DEEPER MOISTURE. THE AMOUNT OF
MOISTURE AND TIMING OF THE WAVE DIFFERS IN THE MODELS...SO WILL JUST
KEEP LOW CHANCE POPS IN THE NORTHWEST WIND FAVORED LOCATIONS INTO
SUNDAY.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 630 AM EST MON DEC 17 2012
UPDATE AT 1130 AM EST...EXPECT CLOUDS TO PERSIST THROUGH TONIGHT AS
MOISTURE THROUGH 3-4KFT IS TRAPPED BENEATH SUBSIDENCE INVERSION.
LIMITED DRY AIR ADVECTION AND LOW SUN ANGLE FOR MID DECEMBER WILL NOT
HELP MIX OUT THE CLOUDS TODAY EITHER. CIGS SHOULD REMAIN IFR AT IWD
UNTIL TONIGHT WHEN THEY SHOULD TRANSITION TO VFR MID CLOUDS AS WINDS
BECOME MORE SOUTHWEST HELPING TO SCATTER OUT THE LOW CLOUDS. SIMILAR
FATE FOR THE CURRENT MVFR CLOUD DECK IS EXPECTED TONIGHT AT CMX AND
SAW. EXPECT OVC VFR MID CLOUD DECK BY SUNRISE TUESDAY AT ALL THE TAF
SITES.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 406 AM EST MON DEC 17 2012
AS HIGH PRESSURE SHIFTS INTO THE AREA TODAY...WEST TO NORTHWEST
WINDS OF 15 TO 25 KTS WILL DIE DOWN TO GENERALLY LESS THAN 15 KTS BY
LATE TONIGHT.
MAIN TIME OF CONCERN FOR THE MARINE FORECAST IS DURING THE END OF
THE WEEK AS A LOW PRESSURE SYSTEM MOVES THROUGH THE CENTRAL GREAT
LAKES. SEEMS VERY LIKELY THAT NORTH TO NORTHWEST GALES OF
35-40KTS WILL OCCUR OVER MUCH OF THE LAKE THURSDAY INTO FRIDAY. THE
NORTHWEST WINDS WILL REMAIN IN PLACE INTO THE WEEKEND...ALTHOUGH T
THEY SHOULD ONLY BE 20-30KTS...AS LAKE SUPERIOR IS SITUATED BETWEEN
THE LOW OVER THE NEW ENGLAND STATES AND HIGH PRESSURE OVER LAKE
WINNIPEG.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...JLA
SHORT TERM...MCD
LONG TERM...SRF
AVIATION...JLA
MARINE...MCD/SRF
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
1149 AM CST MON DEC 17 2012
.UPDATE...
ISSUED AT 1148 AM CST MON DEC 17 2012
BAND OF SNOW HAS BEEN DECREASING IN AREAL COVERAGE AND INTENSITY THE
PAST HOUR WHICH IS IN LINE WITH THE RECENT RUNS OF THE RAP WHICH
DEPICTS THE MID LEVEL FRONTOGENESIS QUICKLY DIMINISHING. HAVE HAD
REPORTS OF 1-2 INCH ACCUMULATIONS WITHIN THE BAND THIS MORNING. WILL
STILL SEE SOME WEAK ASCENT THROUGH THE AFTERNOON AHEAD OF UPPER
TROUGH WHICH BACK IN WESTERN MISSOURI...SO WILL STILL HAVE SOME
AREAS OF -RA OR -RASN THROUGH THE AFTERNOON.
ISSUED AT 928 AM CST MON DEC 17 2012
HAVE BEEN GETTING REPORTS OF SOME LIGHT SNOW ACCUMULATION WITHIN
THE PRECIPITATION BAND THAT CURRENTLY EXTENDS FROM MEXICO TO
PITTSFIELD. THIS IS COINCIDENT WITH A BAND OF MID-LEVEL FRONTOGENESIS
DEPICTED BY THE RAP THAT WILL SINK SOUTH AND DECREASE IN INTENSITY.
FOR NOW HAVE ADDED WINTRY MIX WORDING TO THE NORTHERN THIRD OF THE
CWA WITH SOME MINOR SNOW ACCUMULATIONS. HAVE STUCK WITH JUST RAIN
IN THE FORECAST THIS AFTERNOON AS RAP SOUNDINGS ARE SHOWING A
SLIGHTLY WARMER BOUNDARY LAYER. ALSO LOWERED TEMPERATURES OVER THE
NORTHERN PART OF THE CWA TODAY GIVEN THE PRECIPITATION AND CLOUDS.
BRITT
&&
.SHORT TERM...
ISSUED AT 322 AM CST MON DEC 17 2012
(TODAY THROUGH TUESDAY NIGHT)
THE COLD FRONT WHICH PASSED SOUTH OF OUR AREA YESTERDAY HAS STALLED
OVER NORTHEAST ARKANSAS...THE MISSOURI BOOT HEEL AND EXTREME
SOUTHERN ILLINOIS THIS MORNING. ALOFT...A DEEPENING SHORTWAVE IS
MOVING EAST FROM THE GREAT PLAINS INTO WESTERN MISSOURI. THE
SHORTWAVE WILL CONTINUE MOVING EAST TODAY AND INTERACT WITH A
RELATIVELY SHALLOW LAYER OF LOW LEVEL MOISTURE. RADAR OVER
SOUTHEAST KANSAS SHOWS A COUPLE OF BANDS OF LIGHT RAIN MOVING EAST
NORTHEAST. EXPECT THESE BANDS TO CONTINUE MOVING EAST WITH THE
SHORTWAVE TODAY...PERHAPS EXPANDING IN AREAL COVERAGE AS THE WAVE
ENCOUNTERS THE SOMEWHAT DEEPER MOISTURE IN PLACE OVER OUR AREA.
HAVE INCREASED POPS A BIT TO SHOW THIS...HOWEVER...ANY PRECIP THAT
DOES FALL SHOULD BE VERY LIGHT AND MAY NOT MEASURE. TEMPS SHOULD BE
COOLER TODAY ACROSS THE SOUTHERN 1/2 OF THE CWFA BEHIND THE
FRONT...ESPECIALLY IF THERE`S PRECIP IN THE AREA. TEMPS BEHIND THE
FRONT YESTERDAY WERE GENERALLY IN THE LOW TO MID 40S...SO GUIDANCE
TEMPS LOOKED PRETTY REASONABLE.
UPPER LEVEL RIDGE BUILDS OVER THE REGION LATE TONIGHT INTO TUESDAY
WHICH DIVERTS ANOTHER SHORTWAVE TO OUR NORTH. HOWEVER...THE WAVE
TURNS OUR LOW LEVEL FLOW BACK AROUND TO THE SOUTHWEST WHICH QUICKLY
BRINGS WARMER AIR BACK INTO THE MID-MISSISSIPPI VALLEY. FORECAST
SOUNDINGS ARE INDICATING A RELATIVELY CLOUD-FREE DAY AS WELL UNDER
THE UPPER RIDGE...SO EXPECT WARMING BACK INTO THE 50S...NEAR 60 IN
CENTRAL MO. WILL SEE INCREASING HIGH CLOUDS TUESDAY NIGHT AHEAD OF
THE NEXT STORM SYSTEM...THAT AND PERSISTENT SOUTHERLY FLOW OVER MUCH
OF THE AREA SHOULD KEEP TEMPS RELATIVELY MILD IN THE MID TO UPPER
30S.
CARNEY
&&
.LONG TERM...
ISSUED AT 322 AM CST MON DEC 17 2012
(WEDNESDAY THROUGH SUNDAY)
PRIMARY FOCUS CONTINUES TO BE STRONG STORM DEVELOPING WEDNESDAY OVER
THE PLAINS AND MOVING INTO THE MIDWEST WEDNESDAY NIGHT. MODEL
SOLUTIONS ARE...IF ANYTHING...LESS CERTAIN THAN THEY WERE
YESTERDAY. EACH ONE SEEMS TO HAVE A DIFFERENT TRACK FOR THE STORM.
NAM...GFS...AND GEM TAKE THE SURFACE AND 850MB LOW WELL NORTH OF ST.
LOUIS...WHILE THE ECMWF MOVES THE LOW ALMOST DIRECTLY OVER THE METRO
AREA...AND IS ABOUT 6HRS SLOWER IN ITS EASTWARD PROGRESSION OF THE
STORM THAN THE OTHER MODELS. OBVIOUSLY THE SLOWER/MORE SOUTHERN
ECMWF IS MORE FAVORABLE FOR SNOW IN NORTHERN PORTIONS OF THE CWFA.
IT`S ALSO MORE CONSISTENT WITH PREVIOUS MODEL RUNS...SO HAVE LEANED
IN THIS DIRECTION. IF YOU BELIEVE THE ECMWF VERBATIM...RAIN AND
THUNDERSTORMS WILL BE THE RULE ACROSS THE ENTIRE AREA AT LEAST
THROUGH MIDNIGHT...PROBABLY UNTIL SOMETIME BETWEEN 09Z AND 12Z
THURSDAY MORNING. SHOULD SEE PRECIP CHANGE OVER RAPIDLY ACROSS THE
AREA FROM 12Z THROUGH 18Z THURSDAY AS COLD AIR WRAPS AROUND THE
LOW. THE VAST MAJORITY OF THE AREA PROBABLY WON`T EVEN SEE A
DUSTING IN THIS SCENARIO...HOWEVER PARTS OF NORTHEAST MISSOURI AND
WEST CENTRAL ILLINOIS COULD SEE SOME LIGHT ACCUMULATIONS. THE OTHER
BIG IMPACT OF THIS STORM LOOKS TO BE WIND. FORECAST SOUNDINGS ARE
SHOWING WIND GUSTS IN EXCESS OF 35KTS. WILL HAVE TO KEEP AN EYE ON
THIS FOR A POTENTIAL WIND ADVISORY.
REMAINDER OF THE FORECAST LOOKS PRETTY QUIET WITH QUASI-ZONAL FLOW
ALOFT BEHIND THE STORM. LOOKS LIKE TEMPERATURES WILL BE SEASONABLY
COOL FOR FRIDAY AND SATURDAY...WITH COOLING TEMPS ON SUNDAY AS THE
FLOW AMPLIFIES WITH LOW PRESSURE OVER THE EAST COAST PUSHING COLD
CANADIAN AIR SOUTH THROUGH THE MISSISSIPPI VALLEY.
CARNEY
&&
.AVIATION...
ISSUED AT 1148 AM CST MON DEC 17 2012
IFR/MVFR CIGS/VSBYS ARE STILL ACROSS MUCH OF MO/IL AT THIS HOUR.
EXPECT ONLY SLOW IMPROVEMENT IN CIGS TODAY BEFORE GOING VFR
TONIGHT. HAVE INCLUDED -RA OR VCSH IN THE FIRST 1-3 HOURS AHEAD OF
AN UPPER LEVEL DISTURBANCE IN WESTERN MISSOURI. WINDS WILL
GENERALLY BE LIGHT...BUT SHOULD THEN INCREASE OUT OF THE
SOUTHWEST BY MID MORNING TUESDAY.
SPECIFICS FOR KSTL...EXPECT -DZ OR PATCHY -RA TO AFFECT THE TERMINAL
EARLY IN THE PERIOD...BUT THEN EXPECT SLOW IMPROVEMENT IN THE CIGS/VSBYS
LATER THIS AFTERNOON AND TONIGHT. LIGHT WINDS WILL BACK ROM
NORTHWEST TO WEST THROUGH THIS EVENING BEFORE INCREASING OUT OF
THE SOUTHWEST BY MID MORNING TUESDAY.
BRITT
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
349 PM CST MON DEC 17 2012
.DISCUSSION...
THE STORM OF INTEREST IS RAPIDLY APPROACHING THE PACIFIC NORTHWEST COAST.
MODELS AND TIMING TOOLS INDICATE THE DISTURBANCE IS MOVING EAST
SOUTHEAST AT 30KTS AND WILL CONTINUE SO THROUGH WEDNESDAY NIGHT.
SOME MODEL SOLNS ARE SOUTH...NORTH...WETTER AND DRIER. THE ECMWF
HAS BEEN THE MOST CONSISTENT FOCUSING THE BEST FORCING ACROSS SWRN
NEB SOUTH OF INTERSTATE 80. THE GFS...NAM AND GEM HAVE BEEN
WOBBLING NORTH AND SOUTH. THE ECM IS ALSO ABOUT 6 HOURS SLOWER
THAN THE OTHER MODELS AND SHOWS THE DRIEST BOUNDARY LAYER MOISTURE
AND PRODUCES THE LEAST QPF. THE GFS ENSEMBLE H700MB LOW TRACK AND
QPF IS A REASONABLE COMPROMISE IN TERMS OF TIMING AND CAPTURING
AREAS SOUTH OF NEBRASKA HIGHWAY 2 WITH SNOW.
THE FEATURE OF INTEREST APPEARS TO BE VERY STRONG BUT FAST MOVING
MID LEVEL FRONTOGENESIS AND DEFORMATION ALONG AND JUST NORTH OF
THE H700MB LOW. IT IS STRONGLY TILTED POSITIVELY. THIS SHOULD
PRODUCE A RELATIVELY NARROW BAND OF LIGHT TO MODERATE SNOW. THE
NAM IS SHOWING HEAVY SNOW AS TEMPERATURES ARE VERY FAVORABLE FOR
GROWTH AND THE DENDRITIC LAYER WILL BE DESCENDING AS COLD AIR
FILLS IN BEHIND THE H7 LOW. THE QUICK MOTION OF THE STORM MAKES
HEAVY SNOW LESS LIKELY.
ONE THING ALL MODELS AGREE ON ARE WIND SPEEDS. A NRN STREAM
DISTURBANCE MOVING THROUGH THE NRN PLAINS TUESDAY WILL TAP SOME
ARCTIC AIR AND THIS WILL DROP SOUTH WEDNESDAY MORNING AND GET
CAUGHT UP IN THE SFC CYCLONE. WIND SPEEDS WEDNESDAY AFTN SHOULD
INCREASE TO 15 TO 25 MPH WITH SPEEDS APPROACHING 30 MPH ACROSS FAR
SWRN NEB. MOST OF THE SNOW SHOULD BE OVER BY TIME THE WINDS COME
UP BUT THATS PERFECT FOR BLOWING SNOW.
THURSDAY THROUGH SATURDAY...A ZONAL FLOW TAKES OVER ALOFT PRODUCING
CLEAR SKIES A GRADUAL MODERATION IN TEMPERATURES. THE WEATHER MAY
BE QUIET IN NEBRASKA BUT A LARGE UPPER LEVEL RIDGE WILL BUILD
ACROSS ALASKA SUPPORTING THE DEVELOPMENT OF A VERY LARGE ARCTIC
HIGH PRESSURE SYSTEM. THIS HIGH WILL EVENTUALLY DROP SOUTH AND THE
MODELS ARE HAVING TROUBLE TIMING THE EVENTUAL ARCTIC FRONTAL
PASSAGE INTO NEBRASKA. TODAYS MODEL RUNS SUGGEST THE FRONT WILL
DROP IN MONDAY...A DAY OR SO LATER THAN YESTERDAYS MODEL SOLNS. SO
THERE IS A CHANCE OF SNOW MONDAY FOR UPSLOPE CONDITIONS.
OTHERWISE THE FCST IS STRAIGHT FORWARD. THE ARCTIC DRAPE ACROSS
NORTHEAST NEBRASKA WHILL REMAIN IN PLACE TONIGHT THROUGH 14Z
TUESDAY ACCORDING TO THE RUC. SFC LOW PRESSURE WILL DROP SOUTHEAST
ALONG THE FRONT TONIGHT. IT MAY EVEN REMAIN ON TUESDAY BUT THATS
NOT INDICATED BY ANY MODEL. THE TANDEM EFFECT OF THE NRN STREAM
LOW AND THE LOW DROPPING THROUGH NEB TONIGHT SHOULD LIFT THE
ARCTIC FRONT AND CLOUDS NORTH TUESDAY.
&&
.AVIATION...
VISUAL FLIGHT RULES FOR TERMINALS KLBF AND KVTN THROUGH 18/18Z
TUESDAY. SHORT TERM MODELS DIFFER IN AVAILABLE MOISTURE PROFILES
WHERE A BLEND OF THE RUC AND GFS WERE USED THROUGH THE PERIOD. THE
LOW STRATUS AND FOG TO THE EAST OF KVTN WILL CONTINUE TO MOVE SLOWLY
EAST WHILE WEAK RIDGING ALOFT IN THE WEST BREAKS DOWN FOR INCREASING
ZONAL FLOW OVERNIGHT. CLOUD HEIGHTS AOB 7 KFT WITH CEILINGS RANGING
BETWEEN 7 KFT TO 15 KFT THROUGH EVENING. THEN CLEARING OVERNIGHT
THROUGH 18Z TUESDAY.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...CDC
AVIATION...JACOBS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1128 AM CST MON DEC 17 2012
.AVIATION...18Z TAF. LIFR CIGS REMAIN ON THE NORTH AND EASTERN
PERIPHERIES OF THE TERMINAL LATE THIS MORNING...AND THE LOW CLOUD
DECK IS EXPECTED TO GRADUALLY MOVE EASTWARD DURING THE AFTERNOON.
A SURFACE TROUGH ALONG THE EASTERN SLOPES OF THE ROCKIES WILL
SLIDE EAST TODAY AND WINDS WILL BE FAIRLY LIGHT AND VARIABLE FOR A
FEW HOURS BEFORE SHIFTING SOUTHWEST AND SOUTHERLY UNTIL EARLY
EVENING. AS THE TROUGH MOVES THRU TONIGHT...WINDS WILL SHIFT
WESTERLY BEHIND THE SYSTEM.
&&
PREV DISCUSSION... /ISSUED 516 AM CST MON DEC 17 2012/
SHORT TERM...THROUGH WEDNESDAY NIGHT. THE PRIMARY CONCERN DURING
THE NEXT 72 HOURS CONTINUES TO BE STILL APPEARS TO BE OUR FIRST
WIDESPREAD ACCUMULATING SNOW/BLOWING SNOW EVENT OF THE SEASON WED
INTO WED NIGHT. OVERALL LITTLE HAS CHANGED IN PREVIOUS
THINKING...AS CONFIDENCE IS FAIRLY HIGH THAT HEADLINE-WORTHY
CONDITIONS FEATURING AT LEAST A FEW INCHES OF SNOW AND PLENTY OF
WIND BE REALIZED FOR MOST IF NOT ALL OF THE AREA...BUT THE DETAILS
REGARDING TOTAL ACCUMULATION POTENTIAL ARE STILL UNCERTAIN...AND
CAUTION IS ADVISED AGAINST TAKING THE CURRENT SNOWFALL FORECAST
TOO LITERALLY JUST YET AS THE SYSTEM IS STILL WELL OUT OVER THE
PACIFIC.
STARTING OFF AT 09Z THIS MORNING...THERE ARE A FEW PESKY ISSUES TO
CONSIDER WELL BEFORE THE WED STORM ARRIVES. OBJECTIVE SURFACE
ANALYSIS FEATURES A WEAKISH 1007MB LOW OVER THE FAR NORTHERN
CWA...WITH A VERY SUBTLE TROUGH AXIS TRAILING SOUTH NEAR THE
HIGHWAY 281 CORRIDOR...DOING LITTLE MORE THAN SEPARATING A LIGHT
BUT STEADY WESTERLY BREEZE IN WESTERN COUNTIES...FROM SLIGHTLY
MORE SOUTHERLY LIGHT BREEZES IN THE EAST. TEMPS EARLY THIS
MORNING HAVE TRENDED A FEW DEGREES WARMER THAN EARLIER
FORECAST...WITH LOWS LIKELY ENDING UP IN THE MID 20S MOST
AREAS...EXCEPT FOR COLDER IN THE TYPICAL DAWSON/VALLEY COUNTIES
CORRIDOR. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA
REVEAL A MODEST MID LEVEL SHORTWAVE TROUGH AXIS TRACKING DIRECTLY
OVER THE CWA AT THIS HOUR...ALTHOUGH WITH THE MAJORITY OF UPWARD
FORCING ALREADY WELL OFF TO THE EAST...SKIES HAVE LARGELY CLEARED
BEHIND THIS UPPER TROUGH AXIS...WHICH ACTUALLY BROUGHT A NARROW
LINE OF LIGHT SLEET SHOWERS TO PRIMARILY THE SOUTHWESTERN 1/4 OF
THE CWA ON SUNDAY EVENING. UNFORTUNATELY...WHAT ORIGINALLY
APPEARED TO BE A FAIRLY STRAIGHTFORWARD SKY COVER FORECAST HAS
BEEN COMPLICATED BY A FAIRLY SOLID PROTRUSION OF VERY LOW STRATUS
THAT IS CURRENTLY SINKING SOUTH ACROSS NORTH CENTRAL
NEBRASKA...AND IS POISED TO OVERTAKE AT LEAST A FEW COUNTIES IN
THE CWA NORTH OF HIGHWAY 92 OVER THE NEXT FEW HOURS. THIS LOW
CLOUD DECK IS ALSO ASSOCIATED WITH AT LEAST PATCHY FOG WITH
VISIBILITY AROUND/UNDER 1 MILE.
FORECAST WISE...THE OBVIOUS VERY SHORT TERM ISSUE TODAY IS THE
AFOREMENTIONED LOW STRATUS JUST NOW MOVING INTO OUR FAR NORTHERN
COUNTIES...AS THIS WAS NOT WELL-ANTICIPATED BY MODELS AT ALL. THE
LATEST RAP RUNS HAVE FINALLY CAUGHT ONTO IT SOMEWHAT PER THE
950-925MB RELATIVE HUMIDITY FIELDS...AND THUS THE GENERAL
EXPECTATION IS THAT THIS STRATUS AND ASSOCIATED FOG WILL IN FACT
INVADE ROUGHLY THE 5 NORTHEASTERN-MOST COUNTIES SUCH AS
NANCE/GREELEY OVER THE NEXT FEW HOURS...AND POSSIBLY HANG AROUND
WELL INTO THE DAYLIGHT HOURS BEFORE FINALLY PUSHING OUT TO THE
NORTHEAST BY EARLY-MID AFTERNOON. ALTHOUGH THIS STRATUS IS
CURRENTLY NOT EXPECTED TO SINK AS FAR SOUTHWEST AS GRAND
ISLAND/HASTINGS...THIS WILL BEAR WATCHING AS IT COULD GET SOMEWHAT
CLOSE. ALTHOUGH AM CURRENTLY NOT AWARE OF ANY DENSE FOG ASSOCIATED
WITH THIS STRATUS DECK...CURRENTLY HAVE PATCHY FOG IN THE GRIDS
THROUGH 15Z IN BOTH THE NORTHEASTERN AND FAR SOUTHERN CWA...WITH
THE LATTER ASSOCIATED WITH A COMPLETELY SEPARATE AREA OF LOW
STRATUS BARELY SKIRTING SOUTH OF THE AREA ACROSS CENTRAL KS.
MOVING ON TO OTHER ELEMENTS OF TODAY/S FORECAST...THOSE AREAS THAT
DON/T GET SOCKED IN SHOULD REALIZE QUITE A BIT OF SUNSHINE
TODAY...ALTHOUGH AT LEAST THIN MID/HIGH CLOUDS WILL BE ON THE
INCREASE FROM THE WEST THIS AFTERNOON AHEAD OF THE NEXT VERY
SUBTLE MID LEVEL WAVE. AT THE SURFACE...LOW PRESSURE DEVELOPING
ALONG AN AXIS FROM MT TO NORTHWEST NEB TODAY WILL GRADUALLY TURN
BREEZES MORE SOUTHERLY...WITH SUSTAINED SPEEDS AT LEAST 10-15 MPH
IN MOST AREAS WITH SOME HIGHER GUSTS. RAISED HIGHS TEMPS 1-3
DEGREES FROM PREVIOUS FORECAST IN SOME AREAS...BUT OVERALL SIMILAR
TO PREVIOUS WITH MOST NEB ZONES MID-UPPER 40S AND KS ZONES MAINLY
LOW-MID 50S.
TONIGHT...THE NEXT MID LEVEL SHORTWAVE TROUGH WILL TRACK PRIMARILY
ACROSS THE NORTHERN 1/2 OF NEB...WITH ISENTROPIC LIFT AHEAD OF
THIS WAVE POSSIBLY SPARKING SOME FLURRIES OR LIGHT ACCUMULATING
SNOW WITHIN 100 MILES OR SO NORTH/NORTHEAST OF THE CWA...BUT AM
NOT FORECASTING ANY SNOW TO AFFECT OUR LOCAL AREA AT THIS TIME. A
SURFACE LOW ASSOCIATED WITH THIS WAVE WILL TRACK ACROSS NORTHERN
NEB THROUGH THE NIGHT...SIMILAR TO THE ONE THIS MORNING EXCEPT
STRONGER. THIS WILL INDUCE A NOTICEABLY WESTERLY BREEZE
OVERNIGHT...WITH SUSTAINED SPEEDS LIKELY NEAR OR EXCEEDING 15 MPH
FOR AT LEAST A FEW HOURS. DESPITE MOSTLY CLEAR SKIES...THESE WEST
WINDS SHOULD HELP HOLD TEMPS UP FAIRLY EFFICIENTLY. MADE LITTLE
CHANGE TO LOW TEMPS...KEEPING THEM PRIMARILY MID 20S...BUT WOULD
NOT BE SURPRISED TO SEE SOME AREAS HOLD UP CLOSER TO 30.
TUESDAY LOOKS TO BE A FAIRLY TRANQUIL/MILD DAY AHEAD OF THE
APPROACHING PRIMARY STORM SYSTEM...WHICH WILL FINALLY BE COMING
ONSHORE IN SOUTHERN CAL. MEANWHILE...SUBTLE SHORTWAVE RIDING WILL
DOMINATE THE CENTRAL PLAINS ALOFT...WHILE AT THE
SURFACE...FAIRLY LIGHT BUT STEADY WESTERLY BREEZES WILL PREVAIL IN
THE WAKE OF THE LOW DEPARTING EAST TOWARD THE LOWER GREAT LAKES.
MADE VERY LITTLE CHANGE TO HIGHS...AS THIS SHOULD BE THE MILDEST
DAY OF THE WEEK IN MOST AREAS AND AM AIMING FOR UPPER 40S
NORTH/NEAR 50 TRI-CITIES AND MID-UPPER 50S KS ZONES.
TUES NIGHT...IT REMAIN PRECIP FREE ACROSS THE CWA...ALTHOUGH
CHANGES WILL GET UNDERWAY AS EAST-NORTHEAST SURFACE WINDS RAMP UP
TO 15+ MPH AS THE NIGHT GOES ON...IN RESPONSE TO CYCLOGENESIS
TAKING PLACE IN THE SOUTHEAST CO/OK PANHANDLE AREA. ALOFT...THERE
IS GOOD MODEL CONSENSUS AMONGST THE NAM/GFS/ECMWF THAT THE
POWERFUL SHORTWAVE AXIS WILL BE NEAR THE 4-CORNERS AT 12Z WED
MORNING. FOR LOW TEMPS...ALMOST NO CHANGE WITH UPPER 20S/LOW 30S.
LAST BUT CERTAINLY NOT LEAST...THE WEDNESDAY INTO WED NIGHT
PERIODS PROMISE TO BE QUITE ACTIVE...BUT AS STATED AT THE
TOP...THE DETAILS REGARDING SNOW ACCUMULATIONS ARE STILL A BIT
SKETCHY. IN SHORT...MODEL CONSENSUS ON THE TRACK OF THE UPPER WAVE
IS PRETTY DECENT...AS IT MIGRATES FROM THE 4-CORNERS REGION AT
SUNRISE WEDNESDAY...TO OVER THE HEART OF NEB/KS EARLY WED
EVENING...TO SOMEWHERE OVER IA/MO BY SUNRISE THURS MORNING. THE
NAM HAS BEEN A BIT OF AN OUTLIER VERSUS OTHER MODELS IN
INTENSIFYING/CLOSING OFF THE 500MB CIRCULATION DIRECTLY OVER THE
CWA AS THE WAVE PASSES...WHICH IN TURN RESULTS IN SOME FAIRLY
CONCERNING MODEL-GENERATED SNOW AMOUNTS IN EXCESS OF 6 INCHES
MAINLY NORTH OF I-80. HOWEVER...BOTH THE GFS/ECMWF MAINTAIN A BIT
MORE SOUTHERN TRACK OF THE SYSTEM...TAKING THE PRIMARY SURFACE LOW
GENERALLY ACROSS THE OK/KS BORDER INTO CENTRAL MO...VERSUS THE NAM
WHICH TAKES THE SURFACE LOW MORE OVER THE KC METRO AREA. THIS
TRACK WILL OBVIOUSLY PROVE CRITICAL AS TO WHETHER THE NORTHERN 1/2
OR SOUTHERN 1/2 OF THE CWA WILL REALIZE THE MOST SNOW...AND FOR
NOW HAVE GENERALLY USED A BLEND OF MODEL SOLUTIONS FOR THIS
MORNING/S FORECAST...WHICH RESULTS IN A VERY ROUGH STORM TOTAL
SNOW FORECAST OF 2-4 INCHES CWA-WIDE. CERTAINLY IT IS POSSIBLE
THAT SOME AREAS COULD SEE MORE THAN THIS...BUT UNTIL THE TRACK
BECOMES A BIT CLEARER IT WOULD NOT BE WISE TO TRY PINPOINTING
HIGHER THAN THIS. ALTHOUGH THIS IS A FAIRLY PROGRESSIVE
SYSTEM...IT WILL HAVE QUITE A BIT GOING FOR IT IN TERMS OF STRONG
UPPER JET DIVERGENCE AND ASSOCIATED MID LEVEL
FRONTOGENESIS/DEFORMATION. TIMING-WISE...THE GENERAL EXPECTATION
IS THAT SNOW WILL FIRST BREAK OUT MAINLY ACROSS THE NORTHWEST 1/3
OF THE CWA/NORTHWEST OF THE TRI-CITIES/DURING THE MORNING
HOURS...AND THEN RAPIDLY EXPAND ACROSS THE REMAINDER OF THE AREA
WED AFTERNOON INTO WED EVENING...WHILE AT THE SAME TIME SUSTAINED
SPEEDS WILL RAMP UP INTO THE 20-30 MPH RANGE WITH GUSTS TO AROUND
40 MPH...FIRST FROM THE NORTHEAST AND THEN SWINGING AROUND TO THE
NORTHWEST BY EVENING. VISIBILITY RESTRICTIONS WILL BE AN ISSUE FOR
SURE...BUT NOT THINKING BLIZZARD CRITERIA OF WIDESPREAD 1/4 MILE
OR LESS AT THIS POINT. LIKELY 60-70 POPS ARE IN PLACE FOR MUCH OF
THE CWA DURING THE AFTERNOON/EVENING HOURS...AND THESE WILL LIKELY
BE RAISED FURTHER OVER THE NEXT FEW DAYS. AFTER
MIDNIGHT...LINGERED SOME 20-30 POPS WITHIN THE EASTERN 1/2 OF THE
CWA...BUT THE VAST MAJORITY OF ACCUMULATIONS SHOULD BE DONE BY
THEN...AND CERTAINLY SHOULD BE OVER WITH WELL BEFORE SUNRISE.
WINDS SHOULD ALSO DIMINISH SOMEWHAT PRIOR TO SUNRISE...RESULTING
IN IMPROVING VISIBILITIES IN ANY BLOWING SNOW. TEMPS ON WED WILL
ESSENTIALLY RISE VERY LITTLE IF ANY FROM OVERNIGHT LOWS...AND KEPT
HIGHS IN THE LOW 30S EXCEPT IN THE FAR SOUTHEAST...WHERE UPPER 30S
COULD BE ATTAINABLE. ALTHOUGH NOT EXPECTING MUCH OF AN ISSUE WITH
SLEET/FREEZING RAIN WITH THIS SYSTEM...WILL HAVE TO WATCH FAR
SOUTHEAST AREAS AROUND BELOIT KS AS THINGS FIRST GET UNDERWAY...AS
TEMPS ALOFT COULD BE JUST WARM ENOUGH FOR A BRIEF WINTRY MIX
BEFORE AN OUTRIGHT CHANGEOVER TO SNOW. FOR NOW THOUGH...HAVE KEPT
ALL MENTION OF MIXED-PHASE OUT OF THE GRIDS.
LONG TERM...STARTING 12Z THURSDAY. GUIDANCE FROM THE
EC...OPERATIONAL GFS AND GEFS-MEAN ALL SUGGEST MID AND UPPER LEVEL
RIDGING WILL PERSIST OVER THE CENTRAL CONUS THROUGHOUT THE LONG
TERM FORECAST PERIOD. THE OVERALL LACK IN KINEMATIC FORCING SHOULD
PRESENT DRY CONDITIONS AS A RESULT. GUIDANCE FROM THE EC AND
OPERATIONAL GFS SUGGEST THE DEPARTING STORM SYSTEM TO OUR EAST
WILL PROVIDE A STIFF NORTHWEST WIND TO OUR AREA THROUGH MUCH OF
THURSDAY. THE INCREASING POTENTIAL FOR FRESH SNOW PACK ACROSS THE
AREA...WORKING IN CONCERT WITH LOW LEVEL COLD AIR
ADVECTION...MEANS TEMPERATURES WILL PROBABLY HAVE DIFFICULTY
CLIMBING ALL THAT FAR ON THURSDAY. GIVEN THIS...WENT AHEAD AND
UNDERCUT ALLBLEND BY 2-3 DEGREES FOR MANY LOCATIONS ACROSS THE CWA
WHICH PRESENTS HIGHS IN THE LOW 30S FOR THE MOST PART. THERE IS A
CHANCE THURSDAY HIGH TEMPERATURES WILL NEED TO BE DECREASED MORE
IN THE COMING DAYS SHOULD THE ANTICIPATED SNOWFALL MATERIALIZE ON
WEDNESDAY. CLEAR SKIES AND A DECREASING LOW LEVEL WIND
FIELD...ALONG WITH A FEW INCHES OF SNOW ON THE GROUND...WILL
LIKELY PRESENT A COLD NIGHT THURSDAY NIGHT. ~30 DEGREE TEMPERATURE
DROP-OFFS DO NOT SEEM UNREASONABLE GIVEN THE EXPECTED SYNOPTIC
SETUP...WHICH WOULD PROVIDE OVERNIGHT LOWS GENERALLY IN THE LOW
TEENS. ALLBLEND ONLY PROVIDE LOWS IN THE MID TO UPPER TEENS AND AS
A RESULT...WENT AHEAD AND UNDERCUT ALLBLEND BY A COUPLE DEGREES
BUT MUCH LIKE THE HIGHS ON THURSDAY...THERE IS A POSSIBILITY THAT
THURSDAY NIGHT LOWS WILL NEED TO BE DECREASED A BIT MORE IN THE
COMING DAYS. A PERSISTENT WESTERLY COMPONENT TO THE LOW LEVEL WIND
FIELD...ALONG WITH MODEST LOW LEVEL WARM AIR ADVECTION...SHOULD
HELP THE SNOW PACK ERODE QUITE A BIT HEADING INTO FRIDAY...WITH A
RESULTANT WARMING TREND EXPECTED. NO REAL REASON TO DISAGREE WITH
ALLBLEND WHICH PRESENTED AFTERNOON HIGHS IN THE 30S AND 40S AND
FRIDAY NIGHT LOWS IN THE MID TO UPPER TEENS. THERE ARE INDICATIONS
FROM THE EC AND OPERATIONAL GFS OF A BACKDOOR COLD FRONT PUSHING
ACROSS THE AREA HEADING INTO THE DAY SATURDAY...WITH ALLBLEND
PRESENTING A SUBTLE COOLING TREND TO FINISH THE LONG TERM FORECAST
PERIOD. NO REASON TO DISAGREE WITH ALLBLEND SO LEFT SUNDAY HIGH
TEMPERATURE IN THE 30S FOR MOST LOCATIONS ACROSS THE CWA.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1126 AM CST MON DEC 17 2012
.AVIATION...
VISUAL FLIGHT RULES FOR TERMINALS KLBF AND KVTN THROUGH 18/18Z
TUESDAY. SHORT TERM MODELS DIFFER IN AVAILABLE MOISTURE PROFILES
WHERE A BLEND OF THE RUC AND GFS WERE USED THROUGH THE PERIOD. THE
LOW STRATUS AND FOG TO THE EAST OF KVTN WILL CONTINUE TO MOVE
SLOWLY EAST WHILE WEAK RIDGING ALOFT IN THE WEST BREAKS DOWN FOR
INCREASING ZONAL FLOW OVERNIGHT. CLOUD HEIGHTS AOB 7 KFT WITH
CEILINGS RANGING BETWEEN 7 KFT TO 15 KFT THROUGH EVENING. THEN
CLEARING OVERNIGHT THROUGH 18Z TUESDAY.
&&
.PREV DISCUSSION... /ISSUED 1105 AM CST MON DEC 17 2012/
UPDATE...
THIS MORNING THE LOW CLOUDS AND AREAS OF FOG ARE SLOWLY LIFTING
AND MOVING EAST ACROSS THE FAR NORTH CENTRAL THIS MORNING. SHORT
TERM MODELS DIFFER IN MOVING THE STRATUS OUT WITH GRIDS AND
FORECAST PRODUCTS UPDATED TOWARD THE RUC SOLUTION. THE ADDITIONAL
CLOUDS AND LIGHT WINDS WILL PRODUCE LESS MIXING WITH AFTERNOON
HIGHS LOWERED ACROSS THE BOARD AS CLOUDS DEVELOP IN THE WEST...AS
SHOWN IN THE CURRENT SATELLITE LOOP.
PREV DISCUSSION... /ISSUED 534 AM CST MON DEC 17 2012/
AVIATION...FOR THE KLBF AND KVTN TERMINALS THROUGH 12Z TUESDAY.
FOR THE KLBF TERMINAL...MID LEVEL CLOUDINESS WILL INCREASE FROM THE
SOUTHWEST LATER THIS MORNING WITH SCATTERED CIGS AOA 10000
FT AGL POSSIBLE AFTER MID MORNING. MID LEVEL CLOUDINESS WILL TRACK
EAST BY MONDAY EVENING WITH CLEAR SKIES EXPECTED THERE AFTER. FOR
THE KVTN TERMINAL...LOW LEVEL CLOUDINESS IS EXPECTED TO REMAIN JUST
TO THE EAST OF THE TERMINAL THIS MORNING...IMPACTING KANW AND KONL
WITH CIGS BLO 1000 FT AGL AND VSBYS DOWN TO A MILE. MID LEVEL
CLOUDINESS WILL INCREASE EARLY THIS AFTERNOON...WITH SCATTERED TO
BROKEN CIGS AON 10000 FT AGL POSSIBLE AFTER 21Z. AT BOTH
TERMINALS...SOUTHWESTERLY WINDS AROUND 10 KTS ARE EXPECTED
TODAY...WITH A SHIFT TO THE WEST AT 10 KTS TONIGHT.
CLB
PREV DISCUSSION... /ISSUED 303 AM CST MON DEC 17 2012/
DISCUSSION...SURFACE LOW PRESSURE WILL DEVELOP FROM NORTHERN WYOMING
TOWARD NORTHWEST NEBRASKA BY THIS AFTERNOON. SOUTH TO SOUTHWEST
WINDS ARE EXPECTED ACROSS THE FORECAST AREA TODAY AHEAD OF THE LOW.
850 MB TEMPERATURES WILL WARM SEVERAL DEGREES OVER THOSE OF
SUNDAY...AND EXPECTING HIGHS TO ALSO BE SEVERAL DEGREES WARMER AS
THAT WARMER AIR ALOFT MIXES TO THE SURFACE. THE ONE EXCEPTION FOR
THE WARMER HIGHS WILL BE ACROSS FAR SOUTHWEST NEBRASKA...WHERE
VISIBLE SATELLITE IMAGERY FROM LATE SUNDAY AFTERNOON STILL REVEALED
A FAIRLY DENSE SNOWPACK. AS THE AFOREMENTIONED SURFACE LOW MOVES
EAST TONIGHT AND TUESDAY...EXPECT A PACIFIC COLD FRONT TO SWEEP
SOUTHEAST ACROSS THE AREA. THIS FRONT WILL BRING A FEW DEGREES OF
COOLING FOR TUESDAY...ESPECIALLY ACROSS NORTH CENTRAL AND NORTHWEST
NEBRASKA.
ALL EYES THEN ON THE SYSTEM POISED TO AFFECT THE AREA WEDNESDAY. THE
GEM...ECMWF...AND GFS ARE ALL FAIRLY SIMILAR WITH THE TRACK OF THE
SYSTEM. THEY DEEPEN A SURFACE LOW BY MIDDAY WEDNESDAY ACROSS THE
TX/OK PANHANDLE REGION...AND THEN TRACK THE LOW EAST ALONG THE KS/OK
BORDER WEDNESDAY AFTERNOON AND NIGHT. IN THE UPPER LEVELS...A LOW
SHOULD TRACK EASTWARD ACROSS OR VERY CLOSE TO SOUTHWEST AND SOUTHERN
NEBRASKA. THE NAM AND SREF CONTINUE TO BE THE FARTHEST NORTH WITH
BOTH THE SURFACE AND UPPER LEVEL LOWS...BUT ARE TRENDING A LITTLE
SOUTH WITH EACH RUN. WILL DISCARD THE NAM/SREF SOLUTIONS AS THEY
CONTINUE TO TREND SLOWLY SOUTH...AND FOCUS MORE ON THE CONSISTENT
ECMWF AND GFS. NATIONAL GUIDANCE ALSO SHIED AWAY FROM THE NAM...AND
INCORPORATED THE LATEST GFS AND ECMWF INTO THEIR PRECIPITATION
FORECAST. THE NATIONAL FORECAST MATCHED CLOSE TO OUR LOCAL
FORECAST...AND HAS AROUND TWO INCHES OF SNOW ACCUMULATION ALONG
I-80...WITH LESS TO THE NORTH AND MORE TO THE SOUTH. NEARLY FOUR
INCHES IS POSSIBLE TOWARD THE NE/KS BORDER. THIS SNOW EVENT WILL
LARGELY BE DRIVEN BY STRONG FRONTOGENESIS...AND WILL NEED TO WATCH
FOR SIGNS OF POSSIBLE BANDING AND HIGHER SNOWFALL AMOUNTS THAN
CURRENTLY FORECASTED.
AFTER THIS EVENT...SEVERAL DAYS OF DRY AND NEAR SEASONABLE
TEMPERATURES ARE EXPECTED. MODELS BEYOND THE FORECAST PERIOD HINTING
AT A POSSIBLE STORM SYSTEM ORGANIZING ON OR AROUND CHRISTMAS. THIS
WILL BE MONITORED VERY CLOSELY THE NEXT FEW DAYS.
TAYLOR
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...99
AVIATION...KECK
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1105 AM CST MON DEC 17 2012
.UPDATE...
THIS MORNING THE LOW CLOUDS AND AREAS OF FOG ARE SLOWLY LIFTING
AND MOVING EAST ACROSS THE FAR NORTH CENTRAL THIS MORNING. SHORT
TERM MODELS DIFFER IN MOVING THE STRATUS OUT WITH GRIDS AND
FORECAST PRODUCTS UPDATED TOWARD THE RUC SOLUTION. THE ADDITIONAL
CLOUDS AND LIGHT WINDS WILL PRODUCE LESS MIXING WITH AFTERNOON
HIGHS LOWERED ACROSS THE BOARD AS CLOUDS DEVELOP IN THE WEST...AS
SHOWN IN THE CURRENT SATELLITE LOOP.
&&
.PREV DISCUSSION... /ISSUED 534 AM CST MON DEC 17 2012/
AVIATION...FOR THE KLBF AND KVTN TERMINALS THROUGH 12Z TUESDAY.
FOR THE KLBF TERMINAL...MID LEVEL CLOUDINESS WILL INCREASE FROM THE
SOUTHWEST LATER THIS MORNING WITH SCATTERED CIGS AOA 10000
FT AGL POSSIBLE AFTER MID MORNING. MID LEVEL CLOUDINESS WILL TRACK
EAST BY MONDAY EVENING WITH CLEAR SKIES EXPECTED THERE AFTER. FOR
THE KVTN TERMINAL...LOW LEVEL CLOUDINESS IS EXPECTED TO REMAIN JUST
TO THE EAST OF THE TERMINAL THIS MORNING...IMPACTING KANW AND KONL
WITH CIGS BLO 1000 FT AGL AND VSBYS DOWN TO A MILE. MID LEVEL
CLOUDINESS WILL INCREASE EARLY THIS AFTERNOON...WITH SCATTERED TO
BROKEN CIGS AON 10000 FT AGL POSSIBLE AFTER 21Z. AT BOTH
TERMINALS...SOUTHWESTERLY WINDS AROUND 10 KTS ARE EXPECTED
TODAY...WITH A SHIFT TO THE WEST AT 10 KTS TONIGHT.
CLB
PREV DISCUSSION... /ISSUED 303 AM CST MON DEC 17 2012/
DISCUSSION...SURFACE LOW PRESSURE WILL DEVELOP FROM NORTHERN WYOMING
TOWARD NORTHWEST NEBRASKA BY THIS AFTERNOON. SOUTH TO SOUTHWEST
WINDS ARE EXPECTED ACROSS THE FORECAST AREA TODAY AHEAD OF THE LOW.
850 MB TEMPERATURES WILL WARM SEVERAL DEGREES OVER THOSE OF
SUNDAY...AND EXPECTING HIGHS TO ALSO BE SEVERAL DEGREES WARMER AS
THAT WARMER AIR ALOFT MIXES TO THE SURFACE. THE ONE EXCEPTION FOR
THE WARMER HIGHS WILL BE ACROSS FAR SOUTHWEST NEBRASKA...WHERE
VISIBLE SATELLITE IMAGERY FROM LATE SUNDAY AFTERNOON STILL REVEALED
A FAIRLY DENSE SNOWPACK. AS THE AFOREMENTIONED SURFACE LOW MOVES
EAST TONIGHT AND TUESDAY...EXPECT A PACIFIC COLD FRONT TO SWEEP
SOUTHEAST ACROSS THE AREA. THIS FRONT WILL BRING A FEW DEGREES OF
COOLING FOR TUESDAY...ESPECIALLY ACROSS NORTH CENTRAL AND NORTHWEST
NEBRASKA.
ALL EYES THEN ON THE SYSTEM POISED TO AFFECT THE AREA WEDNESDAY. THE
GEM...ECMWF...AND GFS ARE ALL FAIRLY SIMILAR WITH THE TRACK OF THE
SYSTEM. THEY DEEPEN A SURFACE LOW BY MIDDAY WEDNESDAY ACROSS THE
TX/OK PANHANDLE REGION...AND THEN TRACK THE LOW EAST ALONG THE KS/OK
BORDER WEDNESDAY AFTERNOON AND NIGHT. IN THE UPPER LEVELS...A LOW
SHOULD TRACK EASTWARD ACROSS OR VERY CLOSE TO SOUTHWEST AND SOUTHERN
NEBRASKA. THE NAM AND SREF CONTINUE TO BE THE FARTHEST NORTH WITH
BOTH THE SURFACE AND UPPER LEVEL LOWS...BUT ARE TRENDING A LITTLE
SOUTH WITH EACH RUN. WILL DISCARD THE NAM/SREF SOLUTIONS AS THEY
CONTINUE TO TREND SLOWLY SOUTH...AND FOCUS MORE ON THE CONSISTENT
ECMWF AND GFS. NATIONAL GUIDANCE ALSO SHIED AWAY FROM THE NAM...AND
INCORPORATED THE LATEST GFS AND ECMWF INTO THEIR PRECIPITATION
FORECAST. THE NATIONAL FORECAST MATCHED CLOSE TO OUR LOCAL
FORECAST...AND HAS AROUND TWO INCHES OF SNOW ACCUMULATION ALONG
I-80...WITH LESS TO THE NORTH AND MORE TO THE SOUTH. NEARLY FOUR
INCHES IS POSSIBLE TOWARD THE NE/KS BORDER. THIS SNOW EVENT WILL
LARGELY BE DRIVEN BY STRONG FRONTOGENESIS...AND WILL NEED TO WATCH
FOR SIGNS OF POSSIBLE BANDING AND HIGHER SNOWFALL AMOUNTS THAN
CURRENTLY FORECASTED.
AFTER THIS EVENT...SEVERAL DAYS OF DRY AND NEAR SEASONABLE
TEMPERATURES ARE EXPECTED. MODELS BEYOND THE FORECAST PERIOD HINTING
AT A POSSIBLE STORM SYSTEM ORGANIZING ON OR AROUND CHRISTMAS. THIS
WILL BE MONITORED VERY CLOSELY THE NEXT FEW DAYS.
TAYLOR
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM/EXTENDED...COLE
AVIATION/TODAY...KECK
AREA FORECAST DISCUSSION
NWS BUFFALO NY
110 PM EST MON DEC 17 2012
.SYNOPSIS...
CLOUDY SKIES WILL PREVAIL ACROSS THE REGION TODAY WITH RAIN
RETURNING LATE THIS AFTERNOON TO SOUTHWESTERN NEW YORK STATE. A LOW
WILL TRACK ACROSS PENNSYLVANIA AND INTO SOUTHERN NEW ENGLAND WHICH
WILL BRING A STEADY RAIN INTO THE REMAINDER OF THE REGION THIS
EVENING WITH RAIN LINGERING INTO TUESDAY. WARM TEMPERATURES WILL
CONTINUE THROUGH MUCH OF THE WEEK BEFORE A TURN TOWARDS COLDER AND
MORE WINTRY WEATHER BY FRIDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
REGIONAL RADARS THIS EARLY AFTERNOON SHOW THE CWA DRY...THOUGH WE
WILL LOOK SOUTHWARD FOR OUR NEXT BATCH OF RAIN. EXPECT THE RAIN
ACROSS THAT IS ACROSS SOUTHERN OHIO AND NORTHERN WV AROUND NOONTIME
TO REACH THE SOUTHERN TIER LATE THIS AFTERNOON. OTHERWISE CLOUDY
SKIES AND MILD THIS AFTERNOON.
EXPECT ABOVE NORMAL TEMPERATURES FOR MOST LOCATIONS...WITH HIGHS NEAR
OR ABOVE 50 ACROSS THE WESTERN TWO THIRDS OF THE CWA. A DEVELOPING
SOUTHWESTERLY FLOW MAY KEEP BUFFALO FROM RISING MUCH ABOVE 50...BUT
DOWNSLOPING WILL CONTINUE IN THE GENESEE VALLEY AND FINGER LAKES
REGIONS...WHERE TEMPERATURES SHOULD REACH THE LOWER TO MID 50S.
AN UPPER LEVEL TROF AND ASSOCIATED SURFACE LOW WILL TRACK FROM THE
OHIO VALLEY AND INTO THE REGION TONIGHT. NAM BUFKIT INDICATES LIFT
WELL ALOFT ASSOCIATED WITH THE UPPER TROF...AS WELL AS WARM AIR
ADVECTION IN THE MID-LEVELS. GFS/RGEM/NAM AND SREF ENSEMBLES ARE IN
EXCELLENT AGREEMENT IN TERMS OF QPF...AND GIVEN THE LARGE-SCALE
NATURE OF THE PRECIPITATION HAVE A HIGH CONFIDENCE IN MEASURABLE
PRECIPITATION TONIGHT. NOTED THE 09Z HRRR AND THE 06Z RUN OF THE
NAM ARE A BIT SLOWER THAN PREVIOUS GUIDANCE...SO TRY TO BLEND THIS
SLOWER TIMING WITH FASTER MODELS SUCH AS THE GFS. USING THIS
APPROACH...EXPECT RAIN WILL SPREAD FROM SOUTH TO NORTH THIS
EVENING...LIKELY ENTERING WESTERN PORTIONS OF THE SOUTHERN TIER
AROUND OR JUST AFTER.
THIS SHOULD BE A FAIRLY SOAKING RAINFALL...BRINGING AN AVERAGE OF A
HALF INCH OF RAIN TO THE REGION TONIGHT. LOCALLY HIGHER AMOUNTS TO
AN INCH ARE POSSIBLE...WITH THE BEST CHANCE OF THIS IN LOCATIONS
EAST OF ROCHESTER. FORTUNATELY...WARMER AIR SHOULD BE IN PLACE BY
TONIGHT...WITH ALL PRECIPITATION LIKELY FALLING AS RAIN. EXPECT
FOG WILL DEVELOP IN SOME AREAS TONIGHT
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
WIDESPREAD STEADY RAIN WILL BE ACROSS THE AREA TUESDAY MORNING IN
AREA OF STRONG ISENTROPIC ASCENT AHEAD OF THE APPROACHING SURFACE
LOW. LATEST MODELS CONTINUING TO SUGGEST THAT THE LOW WILL REFORM
ALONG THE SOUTHERN NEW ENGLAND COAST DURING THE DAY TUESDAY AND MOVE
UP THE NEW ENGLAND COAST. AS THIS HAPPENS...COLDER AIR WILL BE DRAWN
INTO THE STATE TUESDAY AFTERNOON AND TUESDAY NIGHT. THIS SHOULD
RESULT IN A GRADUAL TRANSITION TO SOME SCATTERED LAKE/OROGRAPHICALLY
ENHANCED RAIN/SNOW SHOWERS WITH ALL SNOW BECOMING LIKELY OVER THE
HIGHER TERRAIN. ANY SNOW ACCUMULATIONS SHOULD BE LIMITED TO LESS
THAN 2 INCHES AND LIKELY CONFINED TO THE HIGHER TERRAIN TUESDAY
NIGHT.
BUILDING HEIGHTS EXPECTED ON WEDNESDAY IN RESPONSE TO STRONG
SHORTWAVE MOVING ACROSS THE FOUR CORNERS REGION. WEAK SURFACE RIDGE
BUILDING ACROSS THE REGION SHOULD BRING MAINLY QUIET WEATHER
WEDNESDAY AND WEDNESDAY NIGHT...ALTHOUGH THERE MAY BE SOME LINGERING
LIGHT PRECIPITATION ACROSS THE NORTH COUNTRY WEDNESDAY. PERHAPS THE
POTENTIAL FOR A TOUCH OF SUN WEDNESDAY MAY HELP TO GET TEMPERATURES
INTO THE UPPER 30S TO LOWER 40S.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
A SIGNIFICANT STORM MAY BRING MUCH MORE IMPACTFUL WEATHER LATE NEXT
WEEK INTO THE WEEKEND BROUGHT ON BY A DIGGING UPPER LEVEL TROUGH
WHICH LOOKS TO TAKE ON A NEGATIVE TILT OVER THE GREAT LAKES. THERE
ARE STILL SOME DIFFERENCES MAINLY IN TIMING OF THE SURFACE LOW WITH
THE 12Z GFS ABOUT SIX HOURS FASTER THAN THE 12Z ECMWF BUT THERE IS
NOW SOME AGREEMENT IN THE TRACK SHIFTING SOMEWHERE OVER THE EASTERN
LAKES THURSDAY THROUGH FRIDAY. THE 12Z GFS SHOWS THE LOW CENTER
TRACKING JUST TO THE NORTHWEST OF THE LAKES WHILE THE 12Z ECMWF
SHOWS THE STORM TRACK ACROSS OUR FORECAST AREA ALONG THE I-90
CORRIDOR. THE GFS TRACK IS A CLIMATOLOGICALLY FAVORED TRACK FOR HIGH
WINDS WITH 12Z BUFKIT PROFILES SHOWING WIND GUSTS TO 50 OR 60 MPH
POSSIBLE ON FRIDAY ONCE THE SYSTEM SHIFTS TO OUR EAST AND COLD
ADVECTION HELPS MIX 60 TO 70 KT WINDS AT 850MB TO THE SURFACE. THE
ECMWF TRACK WOULD NOT BRING WINDS AS STRONG WITH THE CENTER SHIFTING
OVERHEAD.
AHEAD OF THIS POTENTIAL WIND IMPACT SOUTHERLY FLOW EAST OF THE
STORM SYSTEM WILL BRING WARM AIR AND INCREASING MOISTURE. FORECAST
HIGHS ON THURSDAY LOOK TO BE ABOVE NORMAL AVERAGING IN THE MID 40S
ACROSS INLAND AREAS AND UPPER 40S TO NEAR 50 ALONG THE LAKE SHORES
WITH A DOWNSLOPING SOUTHERLY WIND. WITH SUCH MILD TEMPERATURES ANY
CHANCE FOR PRECIPITATION WOULD COME IN THE FORM OF RAIN DURING THE
DAY. THURSDAY NIGHT WE SHOULD SEE A CHANGE TO A PERIOD OF COOLER
WEATHER AS THE UPPER LEVEL TROUGH SHIFTS OVER THE LOWER LAKES AND
THE SURFACE LOW CROSSES NEAR NEW YORK.
THE COOL DOWN CONTINUES FRIDAY INTO SATURDAY WITH BOTH MODELS
SHIFTING THE LOW EAST OR NORTH EAST OF THE FORECAST AREA. LIKELY
PROBABILITIES FOR WIDESPREAD SYNOPTIC SNOW AND GUSTY WINDS ARE ARE
INCLUDED IN THE FORECAST FOR FRIDAY WITH SURFACE TEMPERATURES ONLY
IN THE 30S. BOTH MODELS CONTINUE TO SHOW COLD AIR IN PLACE THROUGH
THE WEEKEND WITH WEST TO NORTHWEST WINDS OVER THE LAKES WHICH
FAVORS A SET UP FOR ACCUMULATING LAKE EFFECT SNOW DOWN WIND OF
THE LAKES OVER THE WEEKEND.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AT 18Z MVFR AND VFR FLIGHT CONDITIONS WERE FOUND ACROSS THE REGION
TO START THE TAF PACKAGE. TO OUR SOUTH THIS EARLY AFTERNOON AN AREA
OF LOW PRESSURE WAS FOUND OVER NORTHERN KENTUCKY WITH THE NORTHERN
SHIELD OF PRECIPITATION NOW REACHING INTO SOUTHERN OHIO AND NORTHERN
WEST VIRGINIA.
THIS SURFACE LOW WILL ADVANCE NORTHEASTWARD AND PASS JUST TO OUR
SOUTH OVERNIGHT ACROSS PENNSYLVANIA. TONIGHT WINDS WILL
DIMINISH...BUT FLOW FROM A NORTHEAST DIRECTION AS THE RAIN NEARS.
THIS LIGHT...BUT NORTHEAST FLOW IS CLIMATOLOGICALLY FAVORED FOR IFR
CIGS AND VSBYS AT ALL TAF SITES. HAVE LOWERED ALL TAF SITES INTO
IFR...AND POSSIBLY BRIEF LIFR WITH A PERIOD OF RAIN OVERNIGHT. AS
THE LOW ADVANCES EASTWARD TOWARDS LONG ISLAND EARLY TUESDAY MORNING
WINDS WILL SHIFT TO A NORTHWESTERLY FLOW AND ALLOW FOR SOME
IMPROVEMENT TOWARDS MVFR.
TOWARDS MORNING A DRY SLOT MAY END THE RAIN FIRST IN THE GENESEE
VALLEY...WITH A DEFORMATION BAND/UPSLOPE SHOWERS LINGERING ACROSS
WNY. AS THE LOW NEAR LI DEEPENS OUR DRY SLOT WILL ERODE WITH SHOWERS
RETURNING EASTWARD ACROSS THE GENESEE VALLEY AND NORTH COUNTRY.
EXPECT STILL MVFR FLIGHT CONDITIONS OVER MUCH OF THE TAF SITES
THROUGH EARLY AFTERNOON.
OUTLOOK...
TUESDAY AFTERNOON AND NIGHT...RAIN ENDING WITH SLOW IMPROVEMENT
BACK TO VFR.
WEDNESDAY...MAINLY VFR.
THURSDAY...DETERIORATING TO MVFR WITH SHOWERS LIKELY IN THE AFTERNOON.
THURSDAY NIGHT...MVFR WITH RAIN SHOWERS CHANGING TO SNOW. GUSTY
WINDS.
FRIDAY...IFR WITH SNOW LIKELY. GUSTY WINDS.
SATURDAY...MVFR/IFR SNOW SHOWERS LIKELY.
&&
.MARINE...
HAVE DROPPED THE SCA FOR THE EASTERN HALF OF LAKE ONTARIO AS WINDS
AND WAVES CONTINUE TO DIMINISH. WAVES WILL STILL NEAR 4 FEET THIS
MORNING ACROSS FAR NORTHEASTERN PORTIONS OF THE LAKE...BUT A
WEAKENING PRESSURE GRADIENT WILL ALLOW THESE WINDS AND WAVES TO
FURTHER DIMINISH THIS AFTERNOON.
WINDS WILL INCREASE AGAIN OUT OF THE NORTHWEST LATER TUESDAY BEHIND
ANOTHER AREA OF LOW PRESSURE. THIS MAY BRING SMALL CRAFT ADVISORY
CONDITIONS ONCE AGAIN...ESPECIALLY ON LAKE ONTARIO. THESE WINDS WILL
CONTINUE TUESDAY NIGHT BEFORE DIMINISHING ON WEDNESDAY.
A STRONGER STORM SYSTEM IS FORECAST TO MOVE INTO THE VICINITY OF THE
LOWER LAKES BY THURSDAY NIGHT AND FRIDAY. THIS MAY BRING A PERIOD OF
STRONGER WINDS...ALTHOUGH THE DETAILS REMAIN VERY UNCERTAIN.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...NONE.
MARINE...NONE.
&&
$$
SYNOPSIS...APFFEL/THOMAS
NEAR TERM...APFFEL/THOMAS
SHORT TERM...TMA
LONG TERM...SMITH
AVIATION...THOMAS
MARINE...APFFEL/THOMAS
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
415 PM EST MON DEC 17 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE NORTHEAST THROUGH THE REGION THIS EVENING. HIGH
PRESSURE WILL BUILD IN FOR TUESDAY AND WEDNESDAY. A STRONG COLD
FRONT WILL SWEEP THROUGH THE AREA ON THURSDAY...BRINGING
PRECIPITATION AND WINDY CONDITIONS.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
AN AREA OF LOW PRESSURE WILL CONTINUE TRACKING NORTHEAST THROUGH
THE ILN CWA THIS EVENING...EVENTUALLY MOVING INTO PENNSYLVANIA AS
A SURFACE COLD FRONT BEGINS ITS PROGRESSION THROUGH THE REGION. ON
THE SOUTH SIDE OF THIS BOUNDARY...WEAK SURFACE BASED INSTABILITY
HAS BEEN ABLE TO JUST NUDGE INTO THE FAR SOUTHERN ILN
COUNTIES...WITH SOME ELEVATED INSTABILITY EXTENDING THROUGH THE
SOUTHERN 1/3 TO 1/2 OF THE CWA. ATMOSPHERIC TEMPERATURE LEVELS ARE
QUITE LOW COMPARED TO A MORE TYPICAL SPRING OR SUMMER SEVERE
EVENT...WHICH HAS FAVORED THE PRODUCTION OF LARGE AMOUNTS OF SMALL
HAIL. MOST OF THE STORMS HAVE STRUGGLED TO GROW TALL ENOUGH TO
GENERATE LARGE HAIL...EVEN AS SHEAR SEEMS SUFFICIENT TO SUPPORT
SOME ORGANIZATION.
A WEAKENING TREND IS EXPECTED TONIGHT...BUT WITH RAP AND NAM12
RUNS INDICATING SOME WEAK INSTABILITY WILL PERSIST IN SOUTHERN
OHIO / NORTHEAST KENTUCKY FOR SEVERAL HOURS. SO...THUNDER WILL BE
KEPT IN THE FORECAST. IN ADDITION...CATEGORICAL POPS WILL BE USED
AS EXTRAPOLATED FROM THE CURRENT BAND OF PRECIPITATION...BEFORE
TAPERING TO LIKELY OVERNIGHT AS THE FORCING MOVES FURTHER AWAY.
NEAR THE BASE OF THE MID-LEVEL TROUGH...AND ON THE BACK SIDE OF
THE SURFACE LOW...ADDITIONAL (GENERALLY LIGHT) PRECIPITATION IS
EXPECTED TO CONTINUE OVERNIGHT ON A WSW-ENE AXIS ACROSS THE
NORTHERN PORTIONS OF THE CWA. TEMPERATURES WILL BE COOLING DOWN
JUST ENOUGH TO ALLOW FOR A WET MIX OF RAIN AND SNOW NEAR THE END
OF THE PRECIPITATION. NO ACCUMULATIONS ARE EXPECTED.
COLD ADVECTION WILL HELP TEMPS APPROACH FREEZING IN THE NORTHWEST
CWA OVERNIGHT...WITH A GRADIENT THAT EXTENDS TO THE LOWER 40S IN
THE SOUTHEAST CORNER.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
THE SURFACE PRESSURE PATTERN WILL REMAIN COMPLICATED THROUGH THE
SHORT TERM...AS A NARROW RIDGE OF HIGH PRESSURE BUILDS IN
TUESDAY...BEFORE LOW PRESSURE MOVES EAST THROUGH THE SOUTHERN
GREAT LAKES TUESDAY NIGHT. IN THE MID LEVELS...A RIDGE WILL BUILD
OVER THE OHIO VALLEY AND SOUTHERN STATES THROUGH WEDNESDAY. DRY
WEATHER WILL CHARACTERIZE THE PERIOD...WITH FLOW REMAINING
GENERALLY SOUTHWESTERLY. TEMPERATURES WILL INCREASE A BIT FROM
TUESDAY TO WEDNESDAY...ESPECIALLY IN THE SOUTHERN COUNTIES. ON THE
OTHER HAND...LIGHTER WINDS AND CLEARING SKIES SHOULD MAKE TUESDAY
NIGHT COOLER THAN MONDAY NIGHT.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
FOR THE PERIOD WEDNESDAY NIGHT INTO THURSDAY NIGHT...A DEEPENING MID
LEVEL TROF AND DEEPENING SFC LOW PRESSURE SYSTEM WILL PULL NORTHEAST
FROM THE SRN PLAINS TO THE GREAT LAKES/OHIO VALLEY REGION. THE TRACK
OF THE SFC LOW CONTINUES TO BE NW OF THE REGION...SO ANY MAJOR
WINTER WEATHER WILL STAY TO OUR NW. THE LOW WILL BE ASSOCIATED WITH
A STRONG COLD FRONT. DEEP MOISTURE COMBINED WITH STRONG SYNOPTIC
SCALE FORCING WILL SPREAD SHOWERS INTO THE WESTERN PARTS OF THE AREA
LATE WEDNESDAY NIGHT...AND WILL CONTINUE TO PUSH EAST INTO
THURSDAY. TEMPERATURES WILL WARM INTO THE LOWER AND MID 50S ON
THURSDAY FOLLOWED BY FALLING TEMPERATURES LATE IN THE DAY INTO
THURSDAY NIGHT. COLD AIR ADVECTION IN THE WAKE OF THE LOW AND FRONT
WILL BRING SOME WRAP AROUND AND LAKE INDUCED SNOW SHOWERS LATE
THURSDAY INTO THURSDAY NIGHT. RIGHT NOW...ANY SNOW ACCUMULATION
SHOULD BE MINOR. WINDY CONDITIONS ARE FORECAST DUE TO A TIGHTENING
PRESSURE GRADIENT AND MOMENTUM TRANSFER IN THE STRONG COLD AIR
ADVECTION BEHIND FRONTAL PASSAGE THURSDAY INTO THURSDAY NIGHT. WILL
CONTINUE TO MENTION THE POSSIBILITY OF 40 MPH TO 50 MPH WIND GUSTS
IN THE HWO PRODUCT.
FOR FRIDAY INTO FRIDAY NIGHT...UPR LVL TROF WILL HAVE CLOSED OFF TO
OUR NORTH AND NORTHEAST...AND WILL MOVE AWAY FROM OUR REGION. CLOUDS
AND LINGERING SNOW SHOWERS ON FRIDAY WILL TAPER OFF FROM SW TO NE
THROUGH THE DAY...FOLLOWED BY CLEARING SKIES FRIDAY NIGHT. HIGHS ON
FRIDAY WILL STRUGGLE TO WARM INTO THE LOWER AND MID 30S.
FOR THE PERIOD SATURDAY THROUGH MONDAY...MODELS CONTINUE TO DISAGREE
WHETHER UPR LVL CLOSED LOW TO OUR NE WILL ROTATE BACK TO THE
SOUTHWEST AND ALLOW COLDER AIR TO INFILTRATE FROM THE NORTH. IF THIS
OCCURS...THERE WILL BE MORE CLOUDS ACRS OUR NORTHERN ZONES WITH LAKE
EFFECT SNOW SHOWERS STAYING DOWNWIND OF THE GREAT LAKES. FOR
NOW...HAVE KEPT THE FORECAST DRY WITH SURFACE HIGH PRESSURE AT LEAST
IN PLACE AT THE SURFACE. HAVE NOT GONE AS COLD AS THE LATEST 17.12Z
ECMWF...AND HAVE RESORTED TO A BLEND OF THIS WITH HPC GUIDANCE.
&&
.AVIATION /21Z MONDAY THROUGH SATURDAY/...
COLD FRONT ALONG I-71 CORRIDOR BETWEEN CVG AND CMH THEN JOGS
SOUTHWEST THROUGH SOUTHERN INDIANA. NORTHWEST OF THE FRONT LIFR
TO IFR CIGS AND IFR TO MVFR VSBYS ARE COMMON WITH AN EAST-
NORTHEAST WIND FIELD. THE WIDESPREAD SHOWERS SOUTHEAST OF THE
FRONT WILL LIKELY NOT AFFECT ANY MORE TAFS OUTSIDE OF KILN AND
POSSIBLY KLCK IN THE NEXT FEW HOURS.
THE SURFACE LOW WILL TRACK NORTHEAST ALONG THE BOUNDARY THIS
AFTERNOON AND EVENING. MVFR CIGS AND VSBYS WILL OCCASIONALLY DROP
LOWER...MORESO OVERNIGHT. RAPID IMPROVEMENT WILL BE FOUND ONCE
NORTHWEST WINDS CAN WORK IN SOMEWHAT DRIER AND COLDER AIR AFTER
MIDNIGHT TONIGHT.
OUTLOOK...MVFR CONDITIONS ARE POSSIBLE THURSDAY. STRONG WINDS ARE
EXPECTED THURSDAY AFTERNOON AND NIGHT.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HATZOS
NEAR TERM...HATZOS
SHORT TERM...HATZOS
LONG TERM...HICKMAN
AVIATION...FRANKS
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
250 PM EST MON DEC 17 2012
.SHORT TERM (TONIGHT AND TUESDAY)...SKIES REMAIN CLOUDY TO MOSTLY
CLOUDY THIS AFTERNOON WITH GENERALLY LIGHT RAIN SHOWERS MOVING NE
ACROSS THE FORECAST AREA ASSOCIATED WITH A WEAK SHORTWAVE ABOUT TO
EXIT THE REGION INTO THE CENTRAL APPALACHIANS. STRONG TO SEVERE
THUNDERSTORMS PRODUCING LARGE HAIL AND HIGH WINDS HAVE DEVELOPED
WITH SCATTERED ACTIVITY MOVING INTO WESTERN KY AND TN JUST WEST OF
BNA. AIR MASS TO THE WEST OF THE PLATEAU BECOMING UNSTABLE AS SKIES
HAVE CLEARED AHEAD OF STRONGER SHORTWAVE MOVING INTO THE MS AND
LOWER OH VALLEYS.
THESE STORMS LIKELY TO CONTINUE NEXT SEVERAL HOURS BEFORE WEAKENING
AS THEY MOVE INTO MORE STABLE AIRMASS IN EAST TN. NAM AND RUC MODELS
FORECAST THIS AREA TO MOVE MOSTLY NE INTO SE KY LATER THIS AFTERNOON
AND EVENING. TEMPERATURES OVER FORECAST AREA ARE NOW IN THE LOWER
50S NE AND HIGHER ELEVATIONS TO MID 50S TO NEAR 60 EXCEPT LOWER 60S
AT CHA. A FEW STRONG TO SEVERE STORMS ARE POSSIBLE EITHER LATE THIS
AFTERNOON OR EARLY EVENING MAINLY PLATEAU AND CENTRAL VALLEY WITH
HAIL TO ONE INCH AND DAMAGING WIND GUSTS. COLD FRONT ALONG MS RIVER
WILL SWING THROUGH THE EASTERN TENNESSEE VALLEY AND MOUNTAINS BY
LATE TONIGHT ENDING PRECIPITATION IN THE SOUTH THIS EVENING. A
SECONDARY FRONT AND SHORTWAVE EARLY TUESDAY WILL ALLOW SHOWERS TO
LINGER ACROSS SW VA AND EXTREME NE TN INTO EARLY TUESDAY MORNING.
SKIES WILL BEGIN TO CLEAR LATE TONIGHT FROM THE SW AND BY TUESDAY
AFTERNOON CLOUDS SHOULD START TO BREAK UP OVER NE SECTIONS. NAM/GFS
GUIDANCE SIMILAR TONIGHT SO FOLLOWED CLOSE AND FOR TUESDAY AS WELL.
HIGHS TUESDAY WILL STILL BE ABOUT 5 DEGREES ABOVE NORMAL ALL AREAS.
.LONG TERM (TUESDAY NIGHT THROUGH MONDAY)...MODELS ARE IN GOOD
AGREEMENT THROUGH THE EXTENDED PERIOD...AND GENERALLY REVEAL ONE
MAIN SYSTEM AFFECTING THE FORECAST AREA ON THURSDAY. HIGH PRESSURE
OVER THE EASTERN HALF OF THE NATION WILL BRING DRY AND TRANQUIL
CONDITIONS OVER THE FORECAST AREA FOR TUESDAY NIGHT AND WEDNESDAY. A
LOW PRESSURE SYSTEM IS THEN PROGGED TO DEVELOP OVER THE SOUTHERN
PLAINS ON WEDNESDAY...WHICH WILL THEN MOVE NORTHEASTWARD ACROSS THE
LOWER OHIO RIVER VALLEY WEDNESDAY NIGHT. A STRONG 850 MB LOW-LEVEL
JET (IN EXCESS OF 50 KT) IS PROGGED TO DEVELOP OVER THE TN RIVER
VALLEY AHEAD OF ITS TRAILING COLD FRONT. MODEL SOUNDINGS AROUND THE
MOUNTAINS INDICATE A VEERING WIND PROFILE...SOUTH TO SOUTHEASTERLY
LOW-LEVEL WINDS PERPENDICULAR TO THE MOUNTAINS...AND A DEEP STABLE
LAYER EXTENDING ABOVE THE MOUNTAIN RIDGES. THUS...IT APPEARS THAT
DAMAGING WINDS DUE TO MOUNTAIN WAVES WILL BE A GOOD POSSIBILITY LATE
WEDNESDAY NIGHT INTO THURSDAY MORNING ALONG THE FOOTHILLS OF THE
MOUNTAINS. FOR NOW...WILL PLAN TO MENTION THIS POSSIBILITY IN THE
HAZARDOUS WEATHER OUTLOOK...BUT HIGH WIND WATCHES AND/OR WARNINGS
MAY BE NEEDED FOR THE FOOTHILLS IN LATER FORECASTS. MODELS AGREE
THAT MOISTURE WILL DECREASE RAPIDLY BEHIND THE COLD FRONT THURSDAY
NIGHT...SO THAT THE CHANGE OVER TO SNOW SHOWERS BEHIND THE FRONT
SHOULD BE QUICK AND MOSTLY LIMITED TO THE HIGHER ELEVATIONS. ANOTHER
WEAK COLD FRONT IS THEN PROGGED TO MOVE THROUGH THE FORECAST AREA
SATURDAY NIGHT OR SUNDAY...BUT THE MODELS INDICATE THAT LIMITED
MOISTURE ASSOCIATED WITH IT SHOULD RESULT MAINLY IN JUST AN INCREASE
IN CLOUDS. AS FOR TEMPS...WILL TREND TOWARD THE GFS GUIDANCE NUMBERS
THROUGH THE EXTENDED PERIOD...WHICH ARE IN GOOD AGREEMENT WITH THE
ENSEMBLE MEANS.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 41 57 35 66 45 / 30 0 0 0 40
KNOXVILLE AIRPORT, TN 42 55 34 64 44 / 40 0 0 0 30
OAK RIDGE, TN 41 54 35 63 45 / 40 0 0 0 30
TRI CITIES AIRPORT, TN 39 51 30 60 38 / 50 10 0 0 20
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
TD/DMG
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
304 PM CST MON DEC 17 2012
.TONIGHT AND TUESDAY...FORECAST CONFIDENCE...MEDIUM
STUBBORN LOW CLOUD DECK CONTINUES ACROSS SOUTHERN WISCONSIN. BULK OF
MODELS CONTINUE TO SUGGEST IT WILL SCATTER OUT LATE AFTERNOON AND
EVENING...BUT MODELS ORIGINALLY HAD THE SUN POKING OUT THIS MORNING.
GIVEN EXTENT OF THIS STRATUS DECK AND RECENT MODEL
PERFORMANCE...KEPT OVERCAST SKIES THROUGH THE NIGHT. THIS IS SIMILAR
TO THE LATEST RAP...WHICH SEEMS TO HAVE A DECENT HANDLE ON THINGS.
STAYED AWAY FROM COLDEST MODELS FOR LOWS AGAIN TONIGHT...WITH THE
CLOUDS EXPECTED TO HANG AROUND.
BIG ISSUE TOMORROW IS WEAK SHORTWAVE AND SFC LOW EXPECTED TO SLIDE
THROUGH THE AREA. MODELS ARE IN BETTER AGREEMENT WITH THE TRACK OF
THIS SYSTEM...BUT THE NAM CONTINUES WITH A FARTHER NORTH SOLUTION
THAN OTHER MODELS. LEANED TOWARD THE SOUTHERN SOLUTION...BUT DID
LEAVE A LITTLE INFLUENCE FROM NAM POSSIBILITY. LATEST NAM HAS
SHIFTED A BIT SOUTH...WHICH IS ENCOURAGING THAT MAYBE SOUTHERN
SOLUTION...OR AT LEAST A BLEND OF SOLUTIONS...WAS THE WAY TO GO.
EITHER WAY...DOES NOT LOOK LIKE A TON OF PRECIP WITH THIS ONE. WILL
PROBABLY BE ALL SNOW IN THE MORNING WITH COLDER TEMPS...POSSIBLY
MIXING WITH RAIN IN THE AFTERNOON AS IT WARMS UP A BIT. NOT
EXPECTING MUCH MORE THAN A COUPLE TENTHS OF AN INCH OF SNOW. THE
BEST CHANCE FOR MEASURABLE WILL BE FROM MADISON WESTWARD WHERE IT
WILL BE COLDER WHEN THE PRECIP MOVES IN.
.TUESDAY NIGHT THROUGH WEDNESDAY...FORECAST CONFIDENCE IS HIGH.
QUIET THIS PERIOD AS WE WAIT FOR THE ARRIVAL OF THE WINTER STORM
FOR THE WESTERN GREAT LAKES. THE LOW DRIFTING THROUGH ON TUESDAY
MAY STILL HAVE SOME LIGHT RAIN/SNOW LINGERING NORTH OF PORT
WASHINGTON AS IT PEELS OFF TO THE EAST EARLY IN THE EVENING.
THE GFS IS THE FASTEST WITH THE ARRIVAL OF PRECIP AHEAD OF THE
STORM ON WEDNESDAY...SPREADING IT ACROSS THE ENTIRE CWA BY 6PM ON
WEDNESDAY. THIS IS AN OUTLIER AND WILL LIMIT ANY AFTERNOON PRECIP
CHANCES TO THE AREA SOUTHWEST OF MADISON.
.WEDNESDAY NIGHT INTO THURSDAY NIGHT...FORECAST CONFIDENCE IS
MEDIUM TO HIGH.
WE ISSUED A WINTER STORM WATCH EARLIER IN THE DAY FOR THE AREA WE
HAD THE HIGHEST CONFIDENCE OF HEAVY SNOW. THIS AREA IS WITHIN THE
OVERLAP REGION OF MOST OF THE THE MODEL SOLUTIONS. I WOULD EXPECT
ADJUSTMENTS TO THIS WATCH OVER THE NEXT FEW FORECAST CYCLES AS THE
MODELS BEGIN TO SETTLE DOWN AND HONE IN ON A CONSENSUS SOLUTION.
HERE/S THE LATEST ON OUR MODEL SUITE THAT CAME IN THIS MORNING.
THE NAM TOOK A 160 MILE SHIFT SOUTH WITH THE 12Z RUN..GOING FROM
THE MOST NORTHERN AND WARM SOLUTION...TO ONE VERY SIMILAR TO THE
GFS. THE GFS DIDN/T CHANGE VERY MUCH...IF ANYTHING IT MOVED A
NOTCH NORTH AND LOOKS WARMER IN IT/S CRITICAL 0-5000FT THERMAL
PROFILE. THE GEM /CANADIAN/ HAS PICKED UP SPEED AND DOESN/T
INTENSIFY UNTIL IT GETS EAST OF US. THE TRACK IS MORE OR LESS
UNCHANGED. AND FINALLY...THE ECMWF /EUROPEAN/ IS STEADY AS CAN
BE...NOT BUDGING MUCH AT ALL IN ITS TRACK. THE ECMWF IS THE MODEL
WITH THE MOST SOUTHERN SOLUTION. IT WOULD BRING MORE SNOW TO THE
SOUTHEAST FORECAST AREA COMPARED TO THE WESTERN AREA.
THE DYNAMIC/FORCING PROFILE HASN/T CHANGED FROM THE OVERNIGHT
INTERPRETATION. THE UPPER SYSTEM IS STILL GOING NEGATIVE TILT AND
INTENSIFYING AS IT MOVES INTO WISCONSIN. THIS WILL CAUSE THE
SURFACE LOW TO DEEPEN RAPIDLY AS IT MOVES INTO NORTHERN
ILLINOIS...VS INTENSIFYING EAST OF US. THIS MAKES THE STORM EVEN
MORE UNTRUSTWORTHY AND DANGEROUS. COLUMN COOLING CAN HAPPEN MUCH
FASTER THAN EXPECTED. THE OMEGA FORCING WITHIN THE DENDRITE
REGION...CROSS-HAIRS...EXPLODES FOR A TIME...HIGHLIGHTING SOME
PRETTY HEAVY SNOW POTENTIAL CENTERED AROUND 12Z THURSDAY MORNING.
THE POTENTIAL FOR THUNDER SNOW IS LOOKING VERY GOOD. QEPV CHARTS
AND SOUNDING ANALYSIS ARE SHOWING LOTS OF POTENTIAL FROM 750MB UP
THROUGH 500MB. PRETTY STEEP LAPSE RATES FOR THIS TIME OF YEAR.
PRECIPITABLE WATER VALUES OFF THE NAM AND THE GFS ARE ALMOST TOO
HIGH...REACHING ABOUT .75 INCH...WHICH IS ABOUT 2 STANDARD
DEVIATIONS ABOVE CLIMO. TYPICAL BIG SNOWSTORMS IN DECEMBER HAVE A
PW OF AROUND .4 TO .5. THIS SPEAKS TO THE WARMTH OF THE NAM AND
GFS. QPF AMOUNTS ARE STILL AROUND 1 INCH. SO...WHERE IT WILL BE ALL
SNOW...THIS MEANS WE COULD SEE SNOW ACCUMS PUSHING 12 INCHES NORTH
AND WEST OF MADISON. BUT...THIS IS FOLLOWING MORE OF A NAM/GFS/EC
BLEND. IF THE MODELS COME IN CLOSER TO THE ECMWF SOUTHERN
SOLUTION...EXPECT MORE SNOW TO THE SOUTHEAST.
WINDS WILL CRANK UP BY LATE MORNING ON THURSDAY WITH GUSTS
POSSIBLY HITTING 35 MPH. THIS COULD LEAD TO BLIZZARD OR NEAR
BLIZZARD CONDITIONS.
EXPECT THE SNOW TO BEGIN WINDING DOWN FROM WEST TO EAST THURSDAY
AFTERNOON INTO THE EVENING. EXPECT WINDS TO STAY UP INTO THE
EVENING...THEN SLOWLY DIMINISH.
.FRIDAY THROUGH MONDAY...FORECAST CONFIDENCE IS HIGH.
COLD HIGH PRESSURE SETTLES IN. LOOKS PRETTY QUIET AND CHILLY THIS
PERIOD.
&&
.AVIATION/00Z TAFS/...
MAINLY MVFR CIGS CONTINUE ACROSS SOUTHERN WISCONSIN. MODELS CONTINUE
TO TRY AND SCATTER THINGS OUT...BUT JUST IS NOT HAPPENING.
CONSIDERING KEEPING THE MVFR STRATUS GOING RIGHT THROUGH THE NIGHT
PER THE LATEST RAP RUN.
LOW PRESSURE WILL SLIDE THROUGH SOUTHERN WISCONSIN
TOMORROW...BRINGING A CHANCE FOR RAIN/SNOW SHOWERS. IF CONDITIONS
HAVE ACTUALLY IMPROVED BY THEN...MAY SEE CIGS GO BACK DOWN AS THE
LOW SLIDES THROUGH. NOT EXPECTING MUCH IN THE WAY OF SNOW
ACCUMULATIONS...BUT COULD SEE A COUPLE TENTHS OF AN INCH. BEST
CHANCE FOR ANY ACCUMULATION WOULD BE FROM MADISON WESTWARD...AS IT
WILL BE COLDER THERE WHEN THE PRECIP MOVES IN.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
AFTERNOON FOR WIZ046-047-051-056>058-062-063-067.
LM...NONE.
&&
$$
TONIGHT/TUESDAY AND AVIATION/MARINE...DDV
TUESDAY NIGHT THROUGH MONDAY...DAVIS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
303 PM CST MON DEC 17 2012
.SHORT TERM...TONIGHT THROUGH THURSDAY
303 PM CST MON DEC 17 2012
MAIN FORECAST CONCERNS ARE ON BRIEF LIGHT SNOW EVENT TOMORROW AND
THE POSSIBLE WINTER STORM LATE WEDNESDAY INTO THURSDAY.
CURRENTLY AS OF 21Z...WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS
SHOWED TROUGHING FROM THE GULF OF ALASKA TO OFF THE PACIFIC
NORTHWEST...A RELATIVELY POTENT SHORTWAVE CROSSING THE NORTHERN
ROCKIES...A WEAK NORTH TO SOUTH ORIENTED SHORTWAVE OVER THE FAR
EASTERN DAKOTAS AND A WEAK RIDGE SANDWICHED IN-BETWEEN THESE
SHORTWAVES. MID LEVEL CLOUDS WERE ASSOCIATED AHEAD OF THE DAKOTAS
SHORTWAVE...WITH A FEW FLURRIES FALLING OUT OF THESE OVER SOUTHWEST
MINNESOTA AND NORTHWEST IOWA. OVER THE FORECAST AREA...STRATUS
PERSISTS...BURIED UNDERNEATH A SUBSIDENCE INVERSION SEEN ON THE 12Z
MPX...GRB AND DVN SOUNDINGS. HAVING LIGHT WINDS ASSOCIATED WITH HIGH
PRESSURE AT THE SURFACE COMBINED WITH BEING AT THE BOTTOM OF THE
DAYLIGHT CYCLE HAS NOT HELPED EITHER TO GET RID OF THE STRATUS.
TEMPERATURES AS A RESULT HAVE NOT CLIMBED A WHOLE LOT FROM MORNING
LOWS. THE STRATUS ACTUALLY EXTENDS WEST ALL THE WAY INTO THE CENTRAL
DAKOTAS. FARTHER WEST...LEE TROUGHING HAS FORMED DOWNSTREAM OF THE
NORTHERN ROCKIES SHORTWAVE...ALSO AIDED BY A 130KT JET NEAR THE
TROPOPAUSE ON THE SOUTH SIDE OF THE SHORTWAVE. THERE HAS BEEN QUITE
A BIT OF PRECIPITATION ACROSS THE NORTHERN ROCKIES AS WELL AS THE
UPPER JET DRIVES IN PACIFIC MOISTURE.
TONIGHT AND TUESDAY...FOCUS IS ON THAT NORTHERN ROCKIES SHORTWAVE.
MODELS ARE IN REALLY GOOD AGREEMENT BRING THE SHORTWAVE INTO
SOUTHERN SOUTH DAKOTA BY 06Z...NEAR SIOUX CITY IOWA BY 12Z...NEAR
DUBUQUE BY 18Z AND CHICAGO BY 00Z. THIS TRACK IS A BIT FARTHER SOUTH
THAN SUGGESTED OVER THE PAST FEW DAYS...WITH PERHAPS THE CANADIAN
AND ECMWF DOING THE BEST JOB ON IT. THE SHORTWAVE AND THE ASSOCIATED
UPPER JET SOUTH OF IT ARE STRONG ENOUGH THAT OUT OF THE CURRENT LEE
TROUGHING A SURFACE LOW IS SUGGESTED TO DEVELOP. THIS LOW OF COURSE
ENDS UP TRACKING WITH THE SHORTWAVE...RESULTING IN A LOW TO
MID-LEVEL FRONTOGENESIS ZONE ON THE NORTH SIDE OF IT. MOISTURE
INITIALLY IS LIMITED...NOTED BY THE CURRENT LACK OF MID-CLOUDS
ACROSS MUCH OF THE PLAINS. HOWEVER...AS WE GO THROUGH TONIGHT...
CONDENSATION PRESSURE DEFICITS ON THE 285-290K SURFACES DECREASE AS
THE LIFT HELPS TO SATURATE THE MID-LEVELS OF THE ATMOSPHERE. SHOULD
SEE A BAND OF LIGHT SNOW BREAK OUT ACROSS SOUTH DAKOTA INTO SOUTHERN
MINNESOTA AND NORTHERN IOWA BY LATE TONIGHT...ON THE NORTH SIDE OF
THE LOW. PERHAPS SOME OF THIS SNOW SQUEAKS INTO WESTERN PORTIONS OF
THE FORECAST AREA TOWARDS 12Z. WITH THE TREND FARTHER SOUTH WITH THE
SHORTWAVE TRACK...HAVE LEANED THE FORECAST MORE TOWARDS THE 17.12Z
GFS/ECMWF IDEA VERSUS THE FARTHER NORTH BUT TRENDING SOUTH 17.12Z
NAM FOR TUESDAY. THE FRONTOGENESIS BAND OF SNOW SHOULD AFFECT MAINLY
I-90 SOUTH AND RAISED PRECIPITATION CHANCES TOWARDS 60 IN THIS AREA.
LIMITED MOISTURE NOTED BY MIXING RATIOS OF 2-3 G/KG ON THE 285-290K
SURFACES WILL KEEP QPF AMOUNTS DOWN TO AT MOST A 0.10 OF AN INCH
TOTAL LIQUID EQUIVALENT. THE LIFT IS PRIMARILY CENTERED BELOW THE
DENDRITIC GROWTH ZONE...KEEPING SNOW TO WATER RATIOS DOWN NEAR 10 TO
1...THUS ONLY UP TO AN INCH OF SNOW IS ANTICIPATED. CONCERN THOUGH
IS THAT THE SNOW IS COMING AT MORNING COMMUTE TIME...SO HAVE ISSUED
AN SPS TO ACCOUNT FOR THIS. PLENTY OF CLOUDS LOOK TO PERSIST THROUGH
THIS PERIOD THUS AGAIN TEMPERATURES IMPACTED BY ADVECTION. WITH THE
FARTHER SOUTH TRACK OF THE LOW...HAVE COOLED HIGHS DOWN FOR TUESDAY.
TUESDAY NIGHT THROUGH THURSDAY...ALL ATTENTION IS ON THE WINTER
STORM POTENTIAL...WHICH RELATES TO THE CURRENT TROUGH OFF THE
PACIFIC NORTHWEST. THAT TROUGH IS COMPOSED OF 2 PARTS...A POTENT
SHORTWAVE NEAR 42N 140 W...AND A COLD SHORTWAVE NEAR THE NORTHERN
BRITISH COLUMBIA COAST. 500MB TEMPS WERE AROUND -40C WITH THE COLD
SHORTWAVE...AND JUST AHEAD OF IT OVER NORTHERN BRITISH COLUMBIA
850MB TEMPS ARE IN THE -15 TO -25C RANGE. THE IDEA SHOWN FOR THE
PAST MANY DAYS IS THAT THESE TWO PARTS ARE EVENTUALLY GOING TO PHASE
UP AFTER CROSSING THE WESTERN U.S....RESULTING IN A DEEPENING WINTER
STORM FROM THE CENTRAL PLAINS INTO THE GREAT LAKES. THE QUESTION HAS
BEEN WHERE DOES THE PHASING OCCUR WITH RESPECT TO OUR LONGITUDE TO
HELP DETERMINE THE EXACT TRACK AND SPEED. THE ANSWER STILL IS NOT
THERE YET...HOWEVER...THE DETERMINISTIC MODEL SPREAD IS SHRINKING
AND SHOULD CONTINUE TO DO SO OVER THE NEXT FEW DAYS AS THE TROUGH
COMES INTO THE WESTERN U.S.. WITH THE 17.12Z MODEL GUIDANCE...TRACK
SPREAD RANGES FROM THE NORTHWEST SOLUTION OF THE NAM TO THE
SOUTHEAST SOLUTION OF THE ECMWF. THE GFS...UKMET AND CANADIAN LIE
IN-BETWEEN. THE NAM HAS BEEN TRENDING SOUTHEAST...THE GFS NORTHWEST
AND THE CANADIAN/ECMWF STAYING FAIRLY CLOSE. THE FORECAST FOLLOWS A
BLEND OF THE GFS...CANADIAN AND ECMWF SCENARIOS SINCE THESE SEEM TO
BE THE MOST LIKELY TO OCCUR GIVEN TRENDS. FOR WHAT ITS WORTH...THE
PAST 4 SREF RUNS ARE VERY CONSISTENT ON A FARTHER NORTHWEST TRACK
CLOSE TO OR EVEN MORE NORTHWEST THAN THE NAM. NEEDLESS TO SAY...
STILL PLENTY OF UNCERTAINTY.
SOME DETAILS...TUESDAY NIGHT INTO WEDNESDAY MORNING SHOULD STAY DRY
AS WE ARE IN-BETWEEN SYSTEMS. BIG QUESTION MARK IS IF WE CAN CLEAR.
MOST MODELS SAY WE CAN...BUT HAVING SNOW ON TUESDAY COMBINED WITH
MODELS NOT DOING THE GREATEST ON THE CURRENT STRATUS YIELDS A MORE
PESSIMISTIC VIEW. AS SUCH...HAVE INCREASED CLOUD COVER AND FURTHER
INCREASES MAY BE NECESSARY. AS THE STORM SYSTEM DEEPENS IN THE
SOUTHERN PLAINS ON WEDNESDAY...A BAND OF FRONTOGENESIS
DEVELOPS/STRENGTHENS UP INTO OUR REGION. THE GFS AND CANADIAN
PRODUCE PRECIPITATION IN THE AFTERNOON AS THEY ARE QUICKER TO
SATURATE THE LOW LEVELS AND TO BRING IN THE FORCING...COMPARED TO
THE ECMWF/NAM/UKMET. HARD TO SAY WHICH GROUP MAY BE MORE CORRECT AT
THIS POINT...THOUGH THE MORE CONSISTENT SIGNAL HAS BEEN TO WAIT
UNTIL WEDNESDAY EVENING TO BRING THE PRECIPITATION IN. THUS...FOR
NOW JUST INCLUDED 20-40 PERCENT CHANCES FROM I-90 SOUTH FOR THE
AFTERNOON. THE MAJORITY OF THE FORECAST AREA SHOULD SEE
PRECIPITATION WEDNESDAY NIGHT INTO THURSDAY MORNING...NO MATTER WHAT
MODEL SOLUTION IS FOLLOWED. IF THERE IS ANYWHERE OF CONCERN DURING
THIS PERIOD THAT MAY NOT SEE PRECIPITATION IT IS OUR FAR NORTHWEST
AS INDICATED BY THE ECMWF. THUS...HIGHEST CHANCES UP AT OR NEAR 100
ARE CONFINED TO THE SOUTHEAST HALF. PRECIPITATION SHOULD START TO
DIMINISH THURSDAY AFTERNOON AS THE SYSTEM HEADS OFF INTO LOWER
MICHIGAN.
IMPACTS/CONCERNS TO WORRY ABOUT WITH THIS WINTER STORM INCLUDE:
1. HEAVY SNOW...PRETTY GOOD MODEL CONSENSUS EXISTS THAT THE TIME
PERIOD WOULD BE WEDNESDAY NIGHT INTO THURSDAY MORNING. EXACT
PLACEMENT OF HEAVIEST SNOW IS STILL UNCERTAIN...BUT FOLLOWING THE
AFOREMENTIONED GFS/ECMWF/CANADIAN BLEND PLACES IT IN THE
SOUTHEASTERN HALF OF THE FORECAST AREA. WITH MAYBE 100 MB OF
DENDRITIC GROWTH AT MOST AND FAIRLY HIGH UP SAY BETWEEN
550-650MB...THE SNOW TO WATER RATIOS SHOULD BE TYPICAL...IN THE
10-15 TO 1 RANGE.
2. MIXED PRECIPITATION TYPES...MODEL CONSENSUS HAS BEEN TO KEEP THE
SYSTEM OFF TO OUR SOUTHEAST...KEEPING OUR AREA IN THE DEEPER COLD
AIR AND THUS SNOW AS THE MAJORITY PRECIPITATION TYPE. HOWEVER...THE
GFS SUGGESTS THAT IF THE SYSTEM CAN WRAP UP ENOUGH...EVEN GRANT AND
CLAYTON COUNTIES COULD END UP WITH SLEET OR RAIN FOR A TIME.
3. BLOWING SNOW/WIND...AS THE SYSTEM DEEPENS ON ITS WAY UP THROUGH
ILLINOIS WEDNESDAY NIGHT AND BEGINS TO PULL AWAY FROM THE AREA ON
THURSDAY...THE PRESSURE GRADIENT TIGHTENS...CAUSING NORTHWEST WINDS
TO INCREASE. THESE WINDS COULD EASILY REACH THE 15-25KT RANGE WITH
HIGHER GUSTS. COMBINING THESE WITH FALLING OR ALREADY ON THE GROUND
SNOW WOULD YIELD BLOWING SNOW...ESPECIALLY ACROSS NORTHEAST IOWA
WHICH HAS THE MOST EXPOSED TERRAIN.
WITH THE NARROWING MODEL SPREAD...ENOUGH CONFIDENCE EXISTED EARLIER
TODAY TO ISSUE A WINTER STORM WATCH FOR ABOUT THE SOUTHEASTERN HALF
OF THE FORECAST AREA. NOTE THAT THE WATCH AREA MAY NOT END UP BEING
THE FINAL WARNING AREA...THUS THE PHRASE WATCH. FURTHER REFINEMENTS
MAY OCCUR...ESPECIALLY ONCE CONFIDENCE INCREASES ENOUGH TO CHANGE
THE WATCHES TO ADVISORIES/WARNINGS.
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY
303 PM CST MON DEC 17 2012
MAIN FORECAST CONCERNS ARE TEMPERATURES THROUGH FORECAST PERIOD.
THE DETERMINISTIC 17.12Z GFS/ECMWF/GEM ARE IN GOOD AGREEMENT WITH
UPPER LEVEL TROUGH OVER THE NORTHEASTERN UNITED STATES AND UPPER
LEVEL RIDGE OVER THE EASTERN ROCKY MOUNTAINS THROUGH 18Z
SATURDAY...THEN THE MODELS BEGIN TO DIVERGE ON STRENGTH OF THE
UPPER LEVEL TROUGH OVER THE NORTHEASTERN UNITED STATES AND UPPER
LEVEL RIDGE OVER THE ROCKY MOUNTAINS. THE 17.12Z ECMWF IS MORE
AMPLIFIED WITH THE UPPER LEVEL TROUGH SATURDAY NIGHT INTO MONDAY
THAN THE 17.12Z GFS/GEM. IF THIS OCCURS...THE UPPER MIDWEST AND
GREAT LAKES REGION WILL REMAIN UNDER NORTHERLY FLOW ALOFT AND A
COLDER AIRMASS WILL FILTER INTO THE AREA. THIS WILL HAVE IMPACTS
ON TEMPERATURES...ESPECIALLY SATURDAY NIGHT INTO MONDAY. THE
17.12Z GFS INDICATES WEST TO EAST ZONAL FLOW ACROSS THE UNITED
STATES AND SLIGHTLY WARMER TEMPERATURES THAN THE 17.12Z ECMWF.
THIS WOULD RESULT IN NEAR NORMAL TEMPERATURES ACROSS FORECAST
AREA. AT THIS TIME...WILL CONTINUE WITH A CONSENSUS BLEND OF
TEMPERATURES...BASED ON THE LOW CONFIDENCE OF UPPER LEVEL FLOW
PATTERN AFTER 18Z SATURDAY.
NO REAL INDICATION OF ANY PRECIPITATION OCCURRING AS THE UPPER
FLOW PATTERN PROGGED IS MOSTLY SUBSIDENT...FAVORING HIGH PRESSURE
AT THE SURFACE.
&&
.AVIATION...THROUGH 18Z TUESDAY
1224 PM CST MON DEC 17 2012
A BROAD EXPANSIVE IFR CLOUD DECK IS IN PLACE OVER THE REGION WITH
SOME SMALL HOLES OF VFR OVER PARTS OF SOUTHWEST MN AND
NORTH CENTRAL IA. HAVE DECIDED TO TAKE A MORE PESSIMISTIC FORECAST
IN THE TAFS WITH NO LARGE CHANGE SEEN IN THE WEATHER PATTERN
OVERNIGHT. HAVE INCLUDED A TEMPO GROUP TO INDICATE THE
POSSIBILITY THAT A FEW BREAKS MAY MOVE INTO THE TAF SITES BUT IT
WILL BE SHORTER LIVED OVERNIGHT.
A WEATHER SYSTEM SHIFTING ACROSS THE AREA ON TUESDAY WILL PROVIDE
LIGHT SNOW AND IFR CONDITIONS TO THE AREA IT IMPACTS. THE SNOW
BAND COULD BE QUITE NARROW WHICH HOLDS THE POTENTIAL TO MISS THE
AIRPORTS. HOWEVER...CONFIDENCE IS HIGH ENOUGH TO PLACE IFR SNOW IN
THE TUESDAY MORNING FORECAST. THIS CAN BE FURTHER REFINED IN
FUTURE TAF ISSUANCES. THE LIGHT SNOW IS EXPECTED TO END IN THE
AFTERNOON FROM WEST TO EAST ACROSS THE AREA.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
303 PM CST MON DEC 17 2012
WI...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
AFTERNOON FOR WIZ034-041>044-053>055-061.
MN...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
AFTERNOON FOR MNZ096.
IA...WINTER STORM WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY
AFTERNOON FOR IAZ010-011-019-029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...DTJ/AJ
AVIATION...BAUMGARDT