Forecast Discussions mentioning any of
"HRRR" "RR" "RUC13" "RUC" received at GSD on 02/24/12
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1110 PM MST TUE FEB 21 2012
.UPDATE...
OBS CONTINUE TO SHOW WINDS INCREASING AT THE AIR FORCE ACADEMY.
NEW RUC GUIDANCE IS INDICATING WINDS WILL LIKELY KEEP UP AT HIGH
WIND CRITERIA OVER THE EAST SLOPES OF THE PIKES PEAK REGION AND C
MTNS THROUGH TOMORROW MORNING. FOR THIS REASON HAVE DECIDED TO
ISSUE A HIGH WIND WARNING THROUGH ABOUT 15Z TOMORROW. /HODANISH
&&
.PREV DISCUSSION... /ISSUED 954 PM MST TUE FEB 21 2012/
UPDATE...
A COUPLE OF THE USAFA AWOS SENSORS ARE INDICATING WINDS REACHING
MARGINAL HIGH WIND CRITERIA OVER THE LAST HOUR OR SO. SOUNDINGS
INDICATE THESE STRONG WINDS WILL LAST UNTIL ABOUT MIDNIGHT AND
WILL ONLY SLOWLY WEAKEN AS THE REVERSE SHEAR DISSIPATES. FOR THIS
REASON I DO NOT PLAN ON ISSUING ANY HIGH WIND HILITES FOR THE
RAMPART RANGE REGION AT THIS TIME.
AVIATION...
VFR CONDITIONS EXPECTED AT ALL 3 TAF SITES NEXT 24H. GUSTY WEST
WINDS WILL BE POSSIBLE AT KPUB NEXT 24H.
WINDS SHOULD STAY LIGHT AT KCOS...BUT STRONG GUSTY SFC WINDS WILL
BE NOTED JUST WEST OF KCOS DURING THE NEXT 24H.
PREV DISCUSSION... /ISSUED 758 PM MST TUE FEB 21 2012/
UPDATE...
MAIN CHANGE WAS TO ISSUE A FIRE WX WATCH FOR TOMORROW FOR THE
PLAINS...AND HAVE DISCUSSED THIS IN MORE DETAIL IN THE FIRE
WEATHER SEGMENT BELOW.
AFTER LOOKING AT THE 00Z NAM ALONG WITH OTHER SHORT TERM GUIDANCE
PRODUCTS...HAVE DECIDED TO NOT ISSUE ANY HIGH WIND HILITES FOR
THE PIKES PEAK REGION. IT WILL BE WINDY...ESPECIALLY IMMEDIATELY
EAST AND SOUTHEAST OF THE PIKES PEAK MASIF...BUT I DO NOT EXPECT
WE WILL SEE WIDESPREAD GUSTS REACHING CRITERIA. /34
FIRE WEATHER...
HAVE ISSUED A FIRE WX WATCH FOR ALL OF THE PLAINS EXCEPT N EL PASO
COUNTY. IT WILL BE BREEZY TO WINDY ACROSS THE REGION TOMORROW AND
RH VALUES AT MANY LOCATIONS WILL BE REACHING CRITERIA. PUEBLO
DISPATCH UPDATED THE FUELS PAGE AND QUITE A FEW COUNTIES ON THE
PLAINS ARE NOW CRITICAL.
THE STRONGEST WINDS ACROSS S EL PASO COUNTY WILL BE IN THE
IMMEDIATE VICINITY OF PIKES PEAK. MANY AREAS EAST OF I-25 IN
SOUTHERN EL PASO COUNTY WILL HAVE LIGHT WINDS TOMORROW.
PREV DISCUSSION... /ISSUED 253 PM MST TUE FEB 21 2012/
SHORT TERM...
(TONIGHT AND WEDNESDAY)
WINDY!!...
CURRENTLY...THE UPPER LEVEL PATTERN CONSISTS OF A LONGWAVE TROUGH
OVER THE CENTRAL CONUS AND HIGH PRESSURE OFF THE WEST COAST. THIS
HAS PUT COLORADO UNDER STRONG NORTHWESTERLY FLOW. OROGRAPHIC
UPSLOPE HAS LED TO LIGHT SNOW FOR THE CENTRAL MOUNTAINS. OTHERWISE
BREEZY CONDITIONS AND DRY WEATHER HAVE SPREAD ACROSS THE REGION.
WINDS ARE CURRENTLY AVERAGING 25 TO 40 MPH FOR MANY
LOCATIONS...ESPECIALLY THE HIGHER ELEVATIONS AND ALONG AND WEST OF
I-25. TEMPERATURES HAVE WARMED THIS AFTERNOON INTO THE UPPER 50S TO
LOWER 60S FOR THE PLAINS.
TONIGHT...STRONG NORTHWESTERLY FLOW WILL CONTINUE ACROSS THE STATE
WITH CONTINUED LIGHT SNOW FOR THE CENTRAL MOUNTAINS. SNOW
ACCUMULATIONS WILL BE MINOR WITH AN INCH OR TWO OVER THE WEST FACING
PEAKS. DRY CONDITIONS WILL PREVAIL FOR THE REST OF THE CWA. THE
MAIN CONCERN WILL BE THE POTENTIAL FOR STRONG WINDS. HIGH-RES
MODELS ARE INDICATING THE POTENTIAL FOR DOWNSLOPE...PRIMARILY ACROSS
THE FRONT RANGE NORTH OF THE PALMER DIVIDE. HOWEVER AREAS OVER
TELLER COUNTY AND WESTERN EL PASO COUNTY WILL LIKELY SEE A PERIOD OF
STRONG WINDS TONIGHT. WINDS GUSTING TO NEAR 70 MPH WILL BE POSSIBLE
OVER THE HIGHER ELEVATIONS...WITH GUSTS IN EXCESS OF 50 MPH POSSIBLE
WEST OF I-25 OVER WESTERN EL PASO COUNTY. A FEW AREAS PRONE TO
STRONG GUSTS COULD SEE AN OCCASIONAL GUST TO HIGH WIND CRITERIA.
WEDNESDAY...SEVERAL THINGS TO TALK ABOUT. STRONG NORTHWESTERLY FLOW
WILL CONTINUE ALOFT WITH CONTINUED LIGHT CENTRAL MOUNTAIN SNOW. A
COMBINATION OF MIXING AND LEE TROUGH WILL HELP BRING THE STRONG
WINDS ALOFT DOWN. WIDESPREAD GUSTY WINDS ARE EXPECTED WITH MANY
AREAS ACROSS THE PLAINS SEEING GUSTS IN EXCESS OF 30 MPH. HIGHER
ELEVATIONS AND THE ADJACENT PLAINS WEST OF I-25 WILL SEE THE
STRONGEST WINDS THROUGHOUT THE DAY. WITH THE STRONG
MIXING...TEMPERATURES ARE FORECAST TO RISE INTO THE UPPER 60S TO
LOWER 70S FOR THE PLAINS. HUMIDITY VALUES ARE EXPECTED TO REMAIN
LOW...WITH VALUES UNDER 15 PERCENT FOR SOUTHERN PORTIONS OF THE
PLAINS. THE COMBINATION OF STRONG WINDS AND LOW HUMIDITY VALUES
WILL PRODUCE HAZARDOUS FIRE WEATHER CONDITIONS...AND CAUTION IS
ADVISED FOR ANY OUTDOOR FLAMES. 88
LONG TERM...
(WEDNESDAY NIGHT THROUGH TUESDAY)
AN UPR TROF WL DROP SOUTH INTO THE STATE WED NIGHT AND
THU...BRINGING COLDER AIR TO THE FORECAST AREA...AND IT LOOKS A
BIT WINDY OVR THE MTS AND SOME OF THE HIGH VALLEYS. WED NIGHT
THERE SHOULD BE SOME SNOW OVER THE CENTRAL CO MTS. THU MORNING
BOTH THE NAM AND THE GFS SHOW SOME PCPN DEVELOPING AND MOVING
SOUTH OVR THE PALMER DVD. THE NAM IS A LITTLE FASTER BRING PCPN TO
THAT AREA THAN THE GFS. WITH SFC HIGH PRESSURE BUILDING INTO THE
SERN PLAINS THRU MORNING...THE LOW LEVEL FLOW BECOMES EASTERLY AND
THE GFS AND NAM MOVE THE FOCUS OF LIGHT PCPN SOUTHWARD TO SRN EL
PASO AND PUEBLO COUNTIES AND UP AGAINST THE WET MTS FOR THE
AFTERNOON HOURS...WHILE THE SFC WINDS BECOME MORE NORTHERLY OVR
MOST OF EL PASO COUNTY AND MOST OF THE FAR SERN PLAINS. BOTH
MODELS HAVE LITTLE QFP ASSOCIATED WITH THIS SYSTEM FOR ERN AREAS.
PCPN DOES CONTINUE OVR THE CENTRAL MTS THRU THU...SNOW
ACCUMULATIONS FOR WED NIGHT THRU THU IS EXPECTED TO GENERALLY BE
3-6 INCHES. RIGHT NOW IT IS LOOKING LIKE HIGHS ON THU SHOULD BE
JUST A LITTLE BELOW NORMAL OVR THE SERN PLAINS AND AROUND NORMAL
FOR THE SAN LUIS VALLEY. THU EVENING THE PCPN IS EXPECTED TO SHIFT
SOUTH TO LAS ANIMAS COUNTY.
IT STILL LOOKS LIKE IT COULD BE FAIRLY WINDY OVR THE HYR
ELEVATIONS THU NIGHT...BUT THEN ON FRI THE GRADIENT OVR THE AREA
STARTS TO DECREASE AS A RIDGE STARTS BUILDING INTO THE AREA. DRY
WX IS THEN EXPECTED FOR FRI WITH AROUND NORMAL TEMPS. SAT THE FLOW
BECOMES MORE WESTERLY AGAIN AS A NEW UPR TROF MOVES INTO THE NRN
U.S. ROCKIES. THE WX WL BE DRY AND TEMPS WELL ABOVE NORMAL. THE UPR
TROF THEN MOVES ACRS THE AREA SAT NIGHT AND SUN MORNING...BRINGING
CHANCES FOR SNOW TO THE CONTDVD AGAIN...AND PROBABLY A LITTLE TO
THE ERN MTS AS WELL AND MAYBE EVEN SOME LIGHT PCPN TO THE LOWER
ELEVATIONS. THAT SYSTEM EXITS THE AREA SUN NIGHT AND THEN
GENERALLY DRY WESTERLY FLOW IS EXPECTED FOR MON. ANOTHER UPR TROF
IS THEN FORECAST TO MOVE OVR THE AREA ON TUESDAY...BRINGING
ANOTHER CHANCE FOR PCPN TO MUCH OF THE AREA.
AVIATION...
VFR CONDITIONS THROUGH THE NEXT 24 HOURS. WINDS CONTINUE TO GUST AT
KPUB AND KCOS WITH THE STRONGEST WESTERLIES AT KPUB. WINDS SHOULD
DIMINISH THROUGH THE AFTERNOON HOURS. THE POTENTIAL FOR DOWNSLOPE
WINDS OFF THE RAMPART RANGE CONTINUES FOR TONIGHT WITH STRONG WIND
GUSTS AT KCOS POSSIBLE BY AROUND 10Z. PRIOR TO THE ONSET OF STRONG
WINDS...LLWS CAN BE EXPECTED. WINDS IN EXCESS OF 35 KTS WILL BE
POSSIBLE THROUGH THE EARLY MORNING HOURS. WINDS ARE FORECAST TO
INCREASE AT KPUB DURING THE MID MORNING HOURS WITH GUSTS THROUGHOUT
THE DAY. 88
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH WEDNESDAY AFTERNOON FOR COZ227>237.
HIGH WIND WARNING UNTIL 8 AM MST WEDNESDAY FOR COZ060-061-081-
082-084-085.
&&
$$
34/34
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1022 PM EST THU FEB 23 2012
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL BRING A WINTRY MIX AND HAZARDOUS
CONDITIONS DURING THE MORNING COMMUTE...GRADUALLY CHANGING OVER
TO RAIN TOWARDS THE MIDDAY INTO AFTERNOON HOURS. GUSTY WINDS ARE
LIKELY FRIDAY NIGHT AND SATURDAY AS THIS STORM EXITS. HIGH
PRESSURE KEEPS CONDITIONS DRY THROUGH MUCH OF THE EARLY WEEK. A
COLD FRONT SWINGS THROUGH NEW ENGLAND MONDAY NIGHT.
&&
.NEAR TERM /UNTIL MIDNIGHT TONIGHT/...
10 PM UPDATE...
THE CALM BEFORE THE STORM. HAVE UPDATED TEMPERATURE AND DEWPOINT
GRIDS ACCORDINGLY TO REFLECT THE LATEST FORECAST TRENDS. FOR THE
MOST PART EVERYTHING REMAINS ON TRACK WITHIN THE NEAR TERM.
WATCHING AN AREA OF CLEARING PER LATEST SATELLITE TRENDS WHICH
SHOULD ALLOW FOR A BRIEF PERIOD OF RADIATIONAL COOLING RESULTING
IN TEMPS TO FALL BELOW FRZG. THIS IS PRESENTLY THE CASE ACROSS
THE CT VALLEY RGN.
&&
.SHORT TERM /MIDNIGHT THROUGH 6 PM FRIDAY/...
10 PM UPDATE...
LOOKING AT 18Z AND LATEST 0Z GUIDANCE ATTESTS TO AN AREA OF
DEFINITIVE FRONTOGENETICAL BANDING /AND STRONG VIGOROUS LIFT THRU
THE DENDRITIC GROWTH ZONE REGION/ ALONG AND SOUTH OF THE MASS
PIKE BEGINNING AROUND 4-5 AM AND CONTINUING ON THROUGH THE MORNING
COMMUTE INTO THE MID-MORNING HRS. CHALLENGES TO OVERCOME CONCERN
THE AMOUNT OF PRECIPITATION EXPECTED COUPLED WITH SFC TEMPS AND
BOUNDARY LYR PROFILE UP TO H7. THE LATEST RUNS FROM THE HRRR AND
0Z NAM /INCLUDING THE 12Z RUNS OF THE NMM- AND ARW- CORE WRF
SOLNS/ HAVE PROGRESSIVELY SHOWN THAT ALTHO INITIALLY PRECIPITATION
MAY START OUT IN THE FORM OF RAIN...THE HEAVY NATURE OF THE PRECIP
SHOULD COOL THE LOWER ATMOS COLUMN DOWN TO ITS RESPECTIVE WET-BULB
TEMP /LIKELY AT OR BELOW FRZG/ RESULTING IN THE RAIN TO TRANSITION
OVER TO SNOW. ANTICIPATING MOST LOCALES WILL LIKELY HOVER AROUND
THE FRZG MARK.
AS THE AREA OF LOW PRES BECOMES MORE DYNAMIC ACROSS THE ERN GRT
LKS RGN...MDL SOUNDINGS ARE HIGHLIGHTING A PRONOUNCED WARMING
AROUND H8 WITH INCREASED S/SWLY FLOW AT THE LOW-MID LVLS WHICH
WILL LIKELY RESULT IN SNOW TO TRANSITION TO SLEET. SPATIAL AND
TEMPORAL SPECIFICS ARE DIFFICULT TO PIN DOWN...BUT ONE THING IS
FOR CERTAIN AND THAT SIMPLY IS THE FACT THAT IT WILL BE A MESSY
MORNING COMMUTE FOR LOCALES ALONG AND S OF THE MASS PIKE WITH A
WINTRY MIX RESULTING IN HAZARDOUS DRIVING CONDITIONS AND REDUCED
VISIBILITIES. IMPORTANT TO NOTE IS THE LIKELY IMPACTS TO METRO
AREAS SUCH AS HARTFORD...PROVIDENCE...AND SOUTH BOSTON.
WILL CONTINUE WITH THE CURRENT WINTER WX ADVISORIES...AND HAVE
ISSUED A SPECIAL WEATHER STATEMENT FOR ALL OTHER AREAS ADVISING OF
ISSUES ANTICIPATED DURING THE MORNING COMMUTE. AM WATCHING
CLOSELY THE LATEST 0Z MDL FCSTS FOR FURTHER GUIDANCE. WILL UPDATE
ACCORDINGLY.
AS FOR SNOW TOTALS...AM EXPECTING BANDING THRU THE S TIER OF NEW
ENGLAND AS STATED PREVIOUSLY ALONG AND S OF THE MASS PIKE. WITH
THE INFLUENCE OF WARMER AIR ALOFT...WE MAY NOT SEE A PROLONGED
PERIOD OF SNOW...AND A TRANSITION OVER TO SLEET. LOOKING AT ACCUMS
AROUND 1-2 INCHES PRESENTLY. WILL UPDATE ACCORDINGLY WITH THE
LATEST FCST GUIDANCE. AS KNOWN THERE ARE DIFFERENCES IN ACCUM
BETWEEN SNOW AND SLEET AS SNOW HAS A FLUFF FACTOR. ELY ONSHORE
FLOW INCREASING WITH THE DEEPENING SYS WILL KEEP MUCH OF THE PRECIP
ALONG THE SHORELINES AS MAINLY RAIN /ALTHO AN INITIAL BURST OF
SNOW CANT BE RULED OUT FOR THE WRN CAPE/.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
HIGHLIGHTS...
* SEASONABLE TEMPERATURES EXPECTED THIS WEEKEND
* COLD FRONT MOVES THROUGH MONDAY NIGHT
* STORM MOVES THROUGH MIDDLE OF NEXT WEEK
MODEL DISCUSSION...23/12Z MODELS ARE IN GOOD AGREEMENT THROUGH EARLY
NEXT WEEK. AFTER THAT THERE ARE SOME DIFFERENCES IN HOW A LOW
PRESSURE MOVES THROUGH THE REGION MID-WEEK. THE GFS BRINGS THE LOW
PRESSURE INSIDE OVER NEW YORK AND NORTHERN NEW ENGLAND. THIS IS A
WARMER SCENARIO WHICH WOULD KEEP MOST OF THE PRECIP LIQUID. THE
ECMWF TAKES A MORE COASTAL TRACK WHICH COULD BRING IN ENOUGH COLD
AIR FOR SOME WINTRY PRECIPITATION.
FRIDAY NIGHT...LOW PRESSURE OVER THE AREA WILL MOVE INTO THE
MARITIMES. AS THE LOW DEPARTS THE AREA...ANY LINGERING PRECIP IN THE
AREA WILL DIMINISH AND GUSTY WINDS WILL DEVELOP AS THE PRESSURE
GRADIENT TIGHTENS.
SATURDAY AND SUNDAY...HIGH PRESSURE BUILDS INTO THE REGION BRINGING
SEASONABLY COOL...DRY WEATHER TO SOUTHERN NEW ENGLAND.
MONDAY...LOW PRESSURE MOVES ACROSS QUEBEC BRINGING A COLD FRONT
THROUGH THE REGION MONDAY NIGHT. AT THIS POINT IT LOOKS LIKE IT
WILL BE A DRY FRONTAL PASSAGE.
TUESDAY THROUGH THURSDAY...LOW PRESSURE APPROACHES THE AREA LATE
TUESDAY INTO WEDNESDAY. AS STATED ABOVE IN THE MODEL DISCUSSION
SECTION...THERE ARE DISCREPANCIES REGARDING THE PATH OF THE LOW.
THE EVENTUAL PATH WILL BE THE MAIN FACTOR IN DETERMINING PTYPE FOR
THIS STORM. THERE IS A POSSIBILITY OF A PERIOD OF WINTRY
PRECIPITATION DURING THIS TIME FRAME.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
TONIGHT...
VFR CONDITIONS FOR MUCH OF THE NIGHT. HIGH PRESSURE MOVES OFFSHORE
AROUND MIDNIGHT...AT WHICH POINT THE SURFACE WINDS BECOME LIGHT
EAST. INCREASING MOISTURE ALOFT WILL BRING INCREASING CLOUDS AT OR
ABOVE 8000 FEET...LIGHT SNOW IN THE CT VALLEY BY 4 AM AND MVFR
CONDITIONS IN THE CT VALLEY BY 6 AM. HIGH CONFIDENCE.
FRIDAY...
PRECIPITATION CHANCES STEADILY INCREASE AFTER 6 AM. EXPECT MIX OF
RAIN/SNOW SOUTH OF THE TURNPIKE WHILE NORTHWARD WILL BE ALL SNOW
FOR MOST OF THE MORNING. HIGH CONFIDENCE THAT TAFS WILL
DETERIORATE TO AT LEAST IFR CONDITIONS DURING THE MORNING...LOW
CONFIDENCE ON TIMING. CONDITIONS WILL GRADUALLY IMPROVE TOWARD
EVENING.
KBOS TERMINAL...
VFR FOR MOST OF THE NIGHT. NORTHWEST WINDS BECOME LIGHT/VARIABLE
DURING THE NIGHT...THEN PICK UP FROM THE EAST LATE AT NIGHT.
CLOUDS LOWER AND THICKEN LATE AT NIGHT WITH MVFR CONDITIONS AROUND
SUNRISE AS PRECIPITATION STARTS. PRECIPITATION MAY START AS LIGHT
SNOW...BUT SHOULD CHANGE TO RAIN DURING THE MORNING. PERIOD OF IFR
CEILINGS/VSBYS IN RAIN DURING FRIDAY. WINDS THEN SHIFT TO WEST
FRIDAY NIGHT WITH CEILINGS/VSBYS IMPROVING. HIGH CONFIDENCE IN TAF
THROUGH 09Z. MODERATE CONFIDENCE THEREAFTER...EXCEPT LOW
CONFIDENCE IN TIMING OF PRECIPITATION CHANGE TO RAIN.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
FRIDAY NIGHT...MODERATE CONFIDENCE. MVFR/IFR CONDITIONS IN -SN
ACROSS THE NW SHOULD IMPROVE TO VFR BY 06Z. WINDS GUST UP TO 30
KNOTS...PARTICULARLY ON THE COAST.
SATURDAY THROUGH TUESDAY...MODERATE TO HIGH CONFIDENCE. VFR. WINDS
GUST UP TO 30 KNOTS SATURDAY...PARTICULARLY ON THE COAST.
&&
.MARINE...
TONIGHT...
WINDS WILL DIMINISH ACROSS THE WATERS AS HIGH PRES BUILDS INTO THE
RGN. EXPECT WAVES TO STILL REMAIN AROUND 5 FEET FOR THE OPEN
WATERS...SMALL CRAFT ADVISORIES ARE CONTINUED. WILL SEE
SEAS BEGIN TO BUILD AFTER MIDNIGHT AND INTO FRIDAY IN RESPONSE TO
A BUILDING SYSTEM THRU THE GREAT LAKES...ELY FLOW TO INCREASE
ALONG WITH WAVE HEIGHTS.
FRIDAY...
STRONG STORM SYSTEM POISED TO LIFT THRU NEW ENGLAND. ELY FLOW WILL
CONTINUE ACROSS THE AREA AND WILL LIKELY TO SEE WINDS GUSTING IN
EXCESS OF 25 KTS WITH BUILDING SEAS UP TO 10 FT. THERE IS A LOW
PROBABILITY OF GALE FORCE WIND GUSTS LATE IN THE PD.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
FRIDAY NIGHT AND SATURDAY...WINDS AND SEAS INCREASE AS LOW PRESSURE
MOVES OVER THE WATERS. A GALE WATCH HAS BEEN ISSUED FOR THIS TIME
PERIOD. EASTERLY WINDS TO START WILL SWITCH AROUND TO THE WEST
EARLY SATURDAY.
SATURDAY NIGHT AND SUNDAY...WINDS AND SEAS DIMINISH AS HIGH PRESSURE
STARTS TO BUILD OVER THE WATERS. SMALL CRAFT ADVISORIES WILL LIKELY
BE NEEDED FOR AT LEAST A PORTION OF THIS TIME.
SUNDAY NIGHT...WINDS BELOW 25 KTS. SEAS WILL BE 5-6 FEET ON THE
OUTER WATERS...DIMINISHING BELOW 5 FEET AFTER MIDNIGHT.
MONDAY...WINDS AND SEAS WILL REMAIN BELOW SMALL CRAFT CRITERIA.
MONDAY NIGHT THROUGH TUESDAY...WINDS AND SEAS WILL RISE FOR A BRIEF
PERIOD MONDAY NIGHT AS A COLD FRONT MOVES ACROSS THE WATERS. THEN
WINDS AND SEAS DIMINISH BELOW SMALL CRAFT CRITERIA AND REMAIN THERE
THROUGH TUESDAY.
&&
.CLIMATE...
FEBRUARY OF 2012 IS SHAPING UP TO BE ANOTHER MONTH WITH WELL ABOVE
NORMAL TEMPERATURES IN SOUTHERN NEW ENGLAND. IN FACT...FROM JULY
2011 ONWARD EVERY MONTH HAS AVERAGED ABOVE NORMAL TEMPERATURES AT
ALL 4 MAJOR CLIMATE SITES.
FEBRUARY MONTHLY AVERAGE AND DEPARTURES THROUGH THE 21TH:
BOSTON - 36.3 DEGREES WHICH IS +5.2 ABOVE NORMAL: TIED FOR 5TH
TOP 5 WARMEST FEBRUARIES IN BOSTON SINCE 1872
1) 38.0 DEGREES IN 1925
2) 37.6 DEGREES IN 1984
3) 37.3 DEGREES IN 1976
4) 36.4 DEGREES IN 1954 AND 1981
5) 36.3 DEGREES IN 2002
PROVIDENCE - 35.2 DEGREES WHICH IS +3.9 ABOVE NORMAL
TOP 5 WARMEST FEBRUARIES IN PROVIDENCE SINCE 1905: NOT IN TOP 5
1) 37.4 DEGREES IN 1981
2) 37.1 DEGREES IN 1984
3) 37.0 DEGREES IN 1998
4) 36.5 DEGREES IN 1997
5) 36.3 DEGREES IN 1949
WINDSOR LOCKS - 35.4 DEGREES WHICH IS +6.4 ABOVE NORMAL: 3RD SO FAR
TOP 5 WARMEST FEBRUARIES IN WINDSOR LOCKS SINCE 1905
1) 36.2 DEGREES IN 1954 AND 1998
2) 35.6 DEGREES IN 1925
3) 35.3 DEGREES IN 1981
4) 34.8 DEGREES IN 1976
5) 34.7 DEGREES IN 1997
WORCESTER - 32.2 DEGREES WHICH IS +5.9 ABOVE NORMAL
TOP 5 WARMEST FEBRUARIES IN WORCESTER SINCE 1892: NOT IN TOP 5
1) 34.0 DEGREES IN 1984
2) 33.4 DEGREES IN 1925
3) 32.9 DEGREES IN 1998
4) 32.8 DEGREES IN 1981
5) 32.4 DEGREES IN 1954
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...WINTER WEATHER ADVISORY FROM 1 AM TO 7 PM EST FRIDAY FOR
MAZ002>004-008>010-026.
NH...WINTER WEATHER ADVISORY FROM 1 AM TO 7 PM EST FRIDAY FOR
NHZ011-015.
RI...NONE.
MARINE...GALE WATCH FROM FRIDAY EVENING THROUGH SATURDAY AFTERNOON FOR
ANZ230>237-250-251-254>256.
SMALL CRAFT ADVISORY UNTIL 7 PM EST FRIDAY FOR ANZ235-237-250-
254>256.
&&
$$
SYNOPSIS...RLG/DUNTEN
NEAR TERM...SIPPRELL
SHORT TERM...SIPPRELL
LONG TERM...RLG
AVIATION...WTB/RLG/DUNTEN
MARINE...RLG/DUNTEN
CLIMATE...WFO BOX
EAST CENTRAL FLORIDA FORECAST DISCUSSION
NWS MELBOURNE FL
908 PM EST THU FEB 23 2012
.DISCUSSION...
...VERY WARM FRIDAY WITH GUSTY SOUTHWEST WINDS...
TONIGHT...THE GRADIENT BETWEEN HIGH PRESSURE RIDGE TO OUR SOUTH
AND AN APPROACHING FRONTAL TROUGH WILL PRODUCE INCREASING SOUTHWEST
LOW LEVEL FLOW INTO FRIDAY. SFC WINDS WILL PARTIALLY DECOUPLE
OVERNIGHT WITH MILD NIGHT TIME LOWS.
EXPECT SOME STRATUS CLOUDS TO DEVELOP OVERNIGHT IN RESIDUAL LL
MOISTURE AND THE OVERNIGHT RUC SHOWS 35 KNOT WINDS AT 925 MB ACROSS
THE NORTH AND ABOUT 20 KNOTS IN THE SOUTH.
FRI...(PREVIOUS) A FRONTAL BOUNDARY WILL MOVE THROUGH NORTH FLORIDA
DURING THE MORNING AND APPROACH THE LOCAL AREA LATE. EXPECT QUITE
GUSTY SURFACE WINDS. WILL BE LIKELY ISSUING A LAKE WIND ADVISORY FOR
A PORTION OF THE AREA WITH 850 MB TEMPS AROUND 16 DEGREES
CELSIUS...MAX TEMPS SHOULD REACH THE UPPER 80S THREATENING RECORDS
AT DAYTONA AND VERO BEACH.
&&
.AVIATION...
CONDITIONS WILL BE VFR THROUGH EARLY THIS EVENING. DURING THE
OVERNIGHT HOURS SOME STRATUS IS EXPECTED TO DEVELOP ESPECIALLY FOR
THE INTERIOR TERMINALS. CEILINGS SHOULD BE NEAR FL010 BUT WILL
PROBABLY DIP A LITTLE BELOW THAT. DO NOT EXPECT THE STRATUS TO HANG
AROUND AS LONG FRI MORNING. GUSTY SOUTHWEST WINDS 20-25 KNOTS SHOULD
OCCUR DURING THE LATE MORNING AND AFTERNOON.
&&
.MARINE...
SFC AND BUOY OBS NO LONGER REQUIRE CAUTION STMT OVERNIGHT. GUIDANCE
HOWEVER FOR FRIDAY SUPPORTS ANOTHER HEADLINE FOR CAUTION FOR WINDS
FOR A GOOD PORTION OF THE WATERS DUE TO A RESURGENCE IN
PRE-FRONTAL SW FLOW.
&&
.FIRE WEATHER...
FRI...MIN RH VALUES WILL BE IN THE UPPER 40S TO LOWER 50S BUT GUSTY
SOUTHWEST WINDS COMBINED WITH VERY WARM TEMPERATURES WILL CAUSE THE
FIRE SPREAD THREAT TO INCREASE TO A HIGH DANGER.
&&
.CLIMATE...
RECORD HIGHS FOR FRIDAY FEB 24
DAB 88 1962
MCO 90 1962
MLB 92 1962
VRB 86 1962
&&
.MLB WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
&&
$$
JP/RW
AREA FORECAST DISCUSSION...UPDATED
NWS TALLAHASSEE FL
515 AM EST Wed Feb 22 2012
...Updated for issuance of Dense Fog Advisory and for 12Z aviation
package...
.Update...
A dense fog advisory has been issued until 9AM EST/8AM CST for
portions of the FL Panhandle, southeast Alabama, southwest Georgia,
and the western Big Bend. Numerous locations within the advisory
area have seen visibilities drop to one quarter mile or less early
this morning. These low visibilities will make travel difficult in
spots until mid-morning when conditions will begin to improve.
.SYNOPSIS...
08Z water vapor and H4 RUC analysis shows northern stream flow
arriving over the Pacific Northwest/British Columbia coast before
carving out a broad longwave trough over much of the CONUS to the
east of the continental divide. A weak impulse embedded within this
flow over the southern Plains will quickly slide eastward toward the
forecast area by this evening. Southern stream flow extends from the
west coast of Mexico eastward over the northern Gulf/Gulf coastal
region, and continues to pump abundant mid/upper level moisture
overhead. One other feature of note, is a cutoff upper low spinning
over the Baja region of Mexico. This energy has been a real "thorn
in our side" the past couple of days as global models have had
significant difficulty with its evolution. Will discuss this further
below.
At the surface, ridge axis runs from the central FL peninsula
northward to our forecast area. Light winds and a slow low level
moisture return on the western periphery of the ridge is resulting
in area of fog this morning. Temperatures are generally in the upper
40s to middle 50s, and with expanding areas of fog/lower clouds,
don`t anticipate much further of a temperature drop.
&&
.SHORT TERM (Today through Friday)...
Today, Weather will start out quiet, however changes will take place
by the end of the day. Surface high pressure currently in place will
shift south and east with time in response to adjusting mass fields
ahead of the weak approaching northern stream impulse. Ahead of this
impulse, low/mid level SW flow will increase allowing a broad WAA
regime to expand across the area. GFS/ECMWF show increasing low
level ascent/upglide along the 295-310K surfaces overtaking the
area, with the deepest ascent/moisture fields over the southern/SE
zones. Always a tough call in these scenarios as to just where the
most numerous showers will end up. Generally speaking, NWP guidance
is often too slow in the development of upglide/WAA precipitation.
Took this into account and allowed showers to develop into the
coastal areas of the FL panhandle around noon, and then quickly
expand north and east through the afternoon. Based on general NWP
agreement in where the deeper lift will occur, have highest rain
chances 60-80% south of a line from Dothan to Moultrie to Valdosta.
Still expect at least some shower activity north of this line based
on latest hi-res ensemble CAM guidance, however confidence in the
overall coverage is lower, and will take PoPs down to 40-50%. In
addition, will add isolated thunderstorms to the grids due to
showalter indices between -2 to 0. Not out of the question that a
few of these storms may be on the strong side (wind gust the main
threat) as strengthening flow will result in deep layer shear
profiles supportive of organized convection.
Tonight, Weak synoptic forcing and best upglide will shift into the
eastern Big Bend/Suwannee River Valley by later this evening, and
then exit our region around midnight. Looks like there may be just
enough forcing left behind to support isolated showers into the
early morning hours, however doesn`t look too impressive and will
allow Pops to drop below 20% for all zones. SW low level flow off
the Gulf will keep our temps warm with lows in the mid/upper
50s inland and lower 60s at the coast.
Thursday, Upper level pattern will begin to amplify as shortwave
energy drops down the backside of the main northern stream trough.
Associated surface low pressure will push east from the Central
Plains toward the Ohio Valley, with a trailing cold front down along
the MS valley. Deep southerly low level flow will give us a rather
warm and humid day for the end of February. Good diurnal mixing and
850mb temps around 14-15C will allow many inland locations to reach
the mid/upper 70s (perhaps a few spots touching 80). Along the
immediate coast temps will be a bit cooler with the flow off the
shelf waters. Model agreement in several hundred J/KG of mixed layer
CAPE during the afternoon argued for a slight rain chances (a
few isolated "pop-up" showers/storms away from the coast).
Friday,
Threat for severe storms is not gone, however the overall threat
has lowered from 24 hours ago. Global guidance members now all agree
that the northern stream trough will not dig enough to grab the
cutoff energy over the Mexican Baja and eject it eastward fast
enough for phasing. This is good news in general as resulting
synoptic lift and kinematic fields appear not as impressive. As the
upper trough moves toward the eastern CONUS, the associated surface
cold front will still approach and cross our region, with a good
chance for a round of showers and storms. GFS has a faster frontal
passage and argues for the best rain chances late Thursday night
into Friday, while the ECMWF suggest during the day Friday/Friday
night. As mentioned above, although the threat has lowered, can`t
let our guard down in term of severe potential, as sufficient shear
for organized convection is still progged by the global guidance.
Will continue to monitor.
&&
.LONG TERM (Friday Night through next Wednesday)...
Guidance is not in good agreement for much of the extended period.
Much of the discrepancy through the weekend is tied to the evolution
of the cut-off low currently dropping into the Baja region of
Mexico. Guidance has all trended towards a much slower solution as
this feature treks east towards the Gulf of Mexico. However, the 00Z
ECMWF/Canadian have the feature picked up by the northern stream
flow Friday night, while the GFS is 12+ hours slower. The main
impact of this slower motion is to develop a more substantial sfc
reflection over the SW Gulf late Saturday which helps push an large
area of overrunning precip into the forecast are on Sunday. The
ECMWF/Canadian solution keeps the area dry for this period. HPC
prefers to quicker solution, and will follow suit with a dry
forecast for Sunday.
Guidance is in somewhat better agreement for Monday into Tuesday as
return flow increases ahead of a deepening trough over the central
states. This should allow for at least scattered PoPs for the region
as a front moves into the southeastern states. Guidance then
diverges substantially with the evolution of the large scale flow
with a multitude of solutions. Guidance seems to generally indicate
some chance for precip Tuesday into Wednesday, so have broadbrushed
slight chance PoPs through the end of the period.
&&
.MARINE...
Surface high pressure will settle south of the forecast waters
through the day allowing a strengthening flow out of the southwest.
Expect cautionary level wind to develop by early this evening and
generally persist through Thursday. A period of advisory level winds
and seas will be possible Thursday night into Friday ahead of an
approaching cold front. Advisory level winds will then shift to the
northwest and north in the wake of this front later Friday into
Friday night.
&&
.AVIATION (Through 12Z Thursday)...
Dense fog and IFR Cigs have
developed at area terminals. Conditions will slowly improve after
sunrise this morning with a possible brief period of VFR this
afternoon. Showers and isolated thunderstorms are expected
by this afternoon, especially at Florida terminals. IFR conditions
will likely redevelop this evening and continue through the
overnight hours.
&&
.FIRE WEATHER...
Low level moisture will remain abundant across the region through
Friday ahead of an approaching front. A drier airmass will move in
during the weekend with RH values dropping into the lower 30s.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 71 59 76 64 72 / 70 40 20 20 70
Panama City 68 61 71 65 68 / 70 30 20 30 60
Dothan 72 57 79 64 67 / 60 20 20 50 60
Albany 71 57 79 65 70 / 40 20 20 40 70
Valdosta 71 60 79 64 74 / 50 50 20 20 60
Cross City 72 61 76 63 76 / 50 60 20 10 50
Apalachicola 67 62 70 65 69 / 70 40 10 20 60
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...Dense Fog Advisory until 8 AM CST this morning for Geneva-
Houston.
GA...Dense Fog Advisory until 9 AM EST this morning for Baker-Ben
Hill-Calhoun-Colquitt-Decatur-Dougherty-Early-Grady-Irwin-
Lee-Miller-Mitchell-Seminole-Terrell-Thomas-Tift-Turner-
Worth.
FL...Dense Fog Advisory until 9 AM EST /8 AM CST/ this morning for
Calhoun-Central Walton-Coastal Bay-Coastal Franklin-Coastal
Gulf-Gadsden-Holmes-Inland Bay-Inland Franklin-Inland Gulf-
Inland Wakulla-Inland Walton-Jackson-Leon-Liberty-South
Walton-Washington.
GM...None.
&&
$$
Update/Synopsis/Short Term/Marine...Mroczka
Long term/Aviation/Fire Wx...Camp
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
400 AM EST Wed Feb 22 2012
.SYNOPSIS...
08Z water vapor and H4 RUC analysis shows northern stream flow
arriving over the Pacific Northwest/British Columbia coast before
carving out a broad longwave trough over much of the CONUS to the
east of the continental divide. A weak impulse embedded within this
flow over the southern Plains will quickly slide eastward toward the
forecast area by this evening. Southern stream flow extends from the
west coast of Mexico eastward over the northern Gulf/Gulf coastal
region, and continues to pump abundant mid/upper level moisture
overhead. One other feature of note, is a cutoff upper low spinning
over the Baja region of Mexico. This energy has been a real "thorn
in our side" the past couple of days as global models have had
significant difficulty with its evolution. Will discuss this further
below.
At the surface, ridge axis runs from the central FL peninsula
northward to our forecast area. Light winds and a slow low level
moisture return on the western periphery of the ridge is resulting
in area of fog this morning. Temperatures are generally in the upper
40s to middle 50s, and with expanding areas of fog/lower clouds,
don`t anticipate much further of a temperature drop.
&&
.SHORT TERM (Today through Friday)...
Today, Weather will start out quiet, however changes will take place
by the end of the day. Surface high pressure currently in place will
shift south and east with time in response to adjusting mass fields
ahead of the weak approaching northern stream impulse. Ahead of this
impulse, low/mid level SW flow will increase allowing a broad WAA
regime to expand across the area. GFS/ECMWF show increasing low
level ascent/upglide along the 295-310K surfaces overtaking the
area, with the deepest ascent/moisture fields over the southern/SE
zones. Always a tough call in these scenarios as to just where the
most numerous showers will end up. Generally speaking, NWP guidance
is often too slow in the development of upglide/WAA precipitation.
Took this into account and allowed showers to develop into the
coastal areas of the FL panhandle around noon, and then quickly
expand north and east through the afternoon. Based on general NWP
agreement in where the deeper lift will occur, have highest rain
chances 60-80% south of a line from Dothan to Moultrie to Valdosta.
Still expect at least some shower activity north of this line based
on latest hi-res ensemble CAM guidance, however confidence in the
overall coverage is lower, and will take PoPs down to 40-50%. In
addition, will add isolated thunderstorms to the grids due to
showalter indices between -2 to 0. Not out of the question that a
few of these storms may be on the strong side (wind gust the main
threat) as strengthening flow will result in deep layer shear
profiles supportive of organized convection.
Tonight, Weak synoptic forcing and best upglide will shift into the
eastern Big Bend/Suwannee River Valley by later this evening, and
then exit our region around midnight. Looks like there may be just
enough forcing left behind to support isolated showers into the
early morning hours, however doesn`t look too impressive and will
allow Pops to drop below 20% for all zones. SW low level flow off
the Gulf will keep our temps warm with lows in the mid/upper
50s inland and lower 60s at the coast.
Thursday, Upper level pattern will begin to amplify as shortwave
energy drops down the backside of the main northern stream trough.
Associated surface low pressure will push east from the Central
Plains toward the Ohio Valley, with a trailing cold front down along
the MS valley. Deep southerly low level flow will give us a rather
warm and humid day for the end of February. Good diurnal mixing and
850mb temps around 14-15C will allow many inland locations to reach
the mid/upper 70s (perhaps a few spots touching 80). Along the
immediate coast temps will be a bit cooler with the flow off the
shelf waters. Model agreement in several hundred J/KG of mixed layer
CAPE during the afternoon argued for a slight rain chances (a
few isolated "pop-up" showers/storms away from the coast).
Friday,
Threat for severe storms is not gone, however the overall threat
has lowered from 24 hours ago. Global guidance members now all agree
that the northern stream trough will not dig enough to grab the
cutoff energy over the Mexican Baja and eject it eastward fast
enough for phasing. This is good news in general as resulting
synoptic lift and kinematic fields appear not as impressive. As the
upper trough moves toward the eastern CONUS, the associated surface
cold front will still approach and cross our region, with a good
chance for a round of showers and storms. GFS has a faster frontal
passage and argues for the best rain chances late Thursday night
into Friday, while the ECMWF suggest during the day Friday/Friday
night. As mentioned above, although the threat has lowered, can`t
let our guard down in term of severe potential, as sufficient shear
for organized convection is still progged by the global guidance.
Will continue to monitor.
&&
.LONG TERM (Friday Night through next Wednesday)...
Guidance is not in good agreement for much of the extended period.
Much of the discrepancy through the weekend is tied to the evolution
of the cut-off low currently dropping into the Baja region of
Mexico. Guidance has all trended towards a much slower solution as
this feature treks east towards the Gulf of Mexico. However, the 00Z
ECMWF/Canadian have the feature picked up by the northern stream
flow Friday night, while the GFS is 12+ hours slower. The main
impact of this slower motion is to develop a more substantial sfc
reflection over the SW Gulf late Saturday which helps push an large
area of overrunning precip into the forecast are on Sunday. The
ECMWF/Canadian solution keeps the area dry for this period. HPC
prefers to quicker solution, and will follow suit with a dry
forecast for Sunday.
Guidance is in somewhat better agreement for Monday into Tuesday as
return flow increases ahead of a deepening trough over the central
states. This should allow for at least scattered PoPs for the region
as a front moves into the southeastern states. Guidance then
diverges substantially with the evolution of the large scale flow
with a multitude of solutions. Guidance seems to generally indicate
some chance for precip Tuesday into Wednesday, so have broadbrushed
slight chance PoPs through the end of the period.
&&
.MARINE...
Surface high pressure will settle south of the forecast waters
through the day allowing a strengthening flow out of the southwest.
Expect cautionary level wind to develop by early this evening and
generally persist through Thursday. A period of advisory level winds
and seas will be possible Thursday night into Friday ahead of an
approaching cold front. Advisory level winds will then shift to the
northwest and north in the wake of this front later Friday into
Friday night.
&&
.AVIATION (Through 06Z Thursday)...
Potential for dense fog remains the big question for the remainder
of the overnight hours. Satellite and surface obs show lowering CIGS
and Vis across FL Panhandle/SE Alabama. Expect these conditions to
spread east overnight. High clouds streaming across the region may
prevent prolonged periods of sub-1/4SM vis. Cigs will be slow to
lift after sunrise with VFR conditions expected only briefly during
the early afternoon. Thereafter, low clouds will move back in by
early evening. Showers will likely impact the Florida terminals this
afternoon. There is a small chance for a thunderstorm, although
confidence too low attm to include in TAF.
&&
.FIRE WEATHER...
Low level moisture will remain abundant across the region through
Friday ahead of an approaching front. A drier airmass will move in
during the weekend with RH values dropping into the lower 30s.
&&
.PRELIMINARY POINT TEMPS/POPS...
Tallahassee 71 59 76 64 72 / 70 40 20 20 70
Panama City 68 61 71 65 68 / 70 30 20 30 60
Dothan 72 57 79 64 67 / 60 20 20 50 60
Albany 71 57 79 65 70 / 40 20 20 40 70
Valdosta 71 60 79 64 74 / 50 50 20 20 60
Cross City 72 61 76 63 76 / 50 60 20 10 50
Apalachicola 67 62 70 65 69 / 70 40 10 20 60
&&
.TAE WATCHES/WARNINGS/ADVISORIES...
AL...None.
GA...None.
FL...None.
GM...None.
&&
$$
Synopsis/Short Term/Marine...Mroczka
Long term/Aviation/Fire Wx...Camp
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
902 PM CST THU FEB 23 2012
.DISCUSSION...
901 PM CST
NO CHANGES TO GOING ADVISORY HEADLINES THIS EVENING. HOWEVER...
FORECAST REMAINS QUITE COMPLEX WITH RESPECT TO SNOW AMOUNTS AND
PRECIP TYPES THROUGH THE EARLY OVERNIGHT HOURS.
EVENING VAPOR IMAGERY SHOWS STRONG SHORT WAVE TROUGH DIGGING
EAST-SOUTHEAST ACROSS IA/MO. MAIN SFC LOW WAS OVER SOUTHERN INDIANA
WITH TROUGH TRAILING BACK THROUGH WESTERN IL/SOUTHERN IA. INITIAL
PUSH OF WARM ADVECTION RAIN/SNOW HAD GENERALLY LIFTED TO/NORTH OF
THE WI BORDER DURING THE EVENING HOURS...WHILE FARTHER TO THE WEST
REGIONAL RADAR MOSAIC DEPICTED EXTENSION OF BROAD DEVELOPING
DEFORMATION BAND FROM SOUTHWEST IA INTO SOUTHERN WI. EVIDENCE OF
FRONTOGENETICALLY FORCED ENHANCED PRECIPITATION WAS NOTED ACROSS FAR
EASTERN IA...JUST NORTH OF THE QUAD CITIES.
MUCH OF THE CWA HAS SEEN A LULL IN MORE ORGANIZED MEASURABLE PRECIP
DURING THE EVENING HOURS. 22-23Z RUNS OF THE HRRR SEEM TO HAVE A
VERY GOOD HANDLE ON TRENDS ACROSS THE REGION THROUGH MID-EVENING...
AND WOULD SUGGEST DEFORMATION PRECIP AXIS WILL GRADUALLY TRANSLATE
EAST ACROSS THE AREA DURING THE OVERNIGHT/FRIDAY MORNING HOURS.
WHILE THE CURRENT BAND NEAR DVN IS IMPRESSIVE LOOKING...HIGH RES
SHORT TERM MODEL TRENDS WOULD SUGGEST THIS WOULD WEAKEN AND BECOME
SOMEWHAT LESS FOCUS AS IT TRANSLATES EASTWARD...THOUGH ENTIRE
DEFORMATION PRECIP AREA WILL LIKELY BECOME A BIT BETTER ORGANIZED.
WITH LESS PRECIPITATION...ESPECIALLY IN THE FORM OF SNOW ACROSS THE
AREA DURING THE EARLY/MID EVENING HORUS...HAVE ADJUSTED SNOWFALL
AMOUNTS DOWN SOMEWHAT FROM PREVIOUS FORECAST...GENERALLY 2-6 INCHES
WITH THE HEAVIER AMOUNTS GENERALLY ALONG/NORTH OF INTERSTATE 88 IN
NORTHERN/NORTHEAST IL. SOME HIGHER AMOUNTS STILL NOT OUT OF THE
QUESTION GIVEN POTENTIAL FOR MESOSCALE BANDING...AND POTENTIAL FOR
CONVECTION...BUT OVERALL CONFIDENCE REMAINS FAIRLY LOW EVEN AT THIS
RELATIVELY CLOSE-IN TIME.
SOUTH OF ROUGHLY A DVN-ORD LINE HOWEVER...THE HRRR WOULD INDICATE
MORE CONVECTIVE SHOWERY TYPE PRECIP...WHICH HAS BEEN OCCURRING AS A
MIX OF RAIN/SNOW/GRAUPEL PER REPORTS IN UPSTREAM AREAS. THIS APPEARS
QUITE REASONABLE AS AREA OF STEEP MID-LEVEL LAPSE RATES...IN EXCESS
OF 7 DEG/KM PER RUC/SPC MESOANALYSIS...WILL CONTINUE TO SPREAD
ACROSS THE SOUTHERN PARTS OF THE CWFA OVERNIGHT. HAVE CONTINUED TO
INDICATE SHOWERS/CHANCE THUNDER CHANGING TO SNOW DURING THE
OVERNIGHT HOURS...WITH SNOWFALL AMOUNTS QUICKLY DECREASING THROUGH
THE I-80 CORRIDOR SOUTHWARD.
RATZER
&&
.PREV DISCUSSION...
322 PM CST
THE WINTER SYSTEM IS STILL OFFERING PLENTY OF COMPLEXITIES INTO
TONIGHT AND FRIDAY MORNING...WITH TRANSITION TIME TO SNOW AND
TOTAL DURATION OF SNOW REMAINING THE MAIN CHALLENGES WITH THE
FORECAST.
WARM AIR ADVECTION DRIVEN PRECIPITATION...AT TIMES LARGE
SNOWFLAKES UNDER THE HIGHEST REFLECTIVITY...HAS LIFTED GRADUALLY
NORTH ACROSS THE AREA THROUGH THE AFTERNOON. THIS HAS BEEN ALONG A
TIGHTENING MID-LEVEL THERMAL GRADIENT WHICH SHOULD NOT MOVE MUCH
FURTHER NORTH AT ALL INTO TONIGHT. THIS OFFERS A LIKELY
INDICATION ON WHERE THE BANDED POTENTIAL AND HEAVIER PRECIPITATION
WILL BE TONIGHT AS THE UPPER WAVE APPROACHES. AT THE SURFACE
...LOW-LEVEL TEMPERATURES AND DEW POINTS HAVE DROPPED THIS
AFTERNOON UNDER PRECIP AND GRADUALLY BACKING WINDS. TEMPERATURES
SHOULD BASICALLY NOT CLIMB ANYMORE WITH THE MAIN WARM FRONT WELL
TO THE SOUTH JUST NORTH OF THE OHIO RIVER. PER VISIBLE
SATELLITE...MOISTURE AND INSTABILITY ARE EVIDENT LIFTING NORTH OF
THIS FRONT ACROSS CENTRAL IL AND IN...EVEN WITH A POSSIBLE
EMBEDDED DISTURBANCE. SCATTERED SHOWERS AND EVEN ELEVATED STORMS
ARE EXPECTED TO DEVELOP IN THAT AREA AND POTENTIALLY CLIP THE
SOUTHEAST FORECAST AREA THIS EVE.
THE MAIN UPPER SYSTEM CONTINUES TO ORGANIZE ACROSS THE MISSOURI
RIVER VALLEY IN ASSOCIATION WITH THE DIGGING 170 KT UPPER LEVEL
JET. AS THIS TRANSLATES EAST...LARGE SCALE ASCENT WILL OVERRIDE
THE EXISTING MID-LEVEL BOUNDARY AND LIKELY LEAD TO A RE-
ENHANCEMENT OF PRECIP EARLY THIS EVENING. STRENGTHENING SYSTEM
MOISTURE RETURN ON A LOW-LEVEL JET...ALMOST MORE OF A LOW LEVEL
/900-750MB/ TROWAL...WILL WRAP INTO THE AREA AS WELL. THE LAPSE
RATES WILL STEEPEN ALOFT THROUGH THE DIFFERENTIAL TEMPERATURE
ADVECTION AND SHOULD BE ENOUGH TO SUPPORT HEAVIER PRECIP RATES
AND MAXIMIZING THE INITIAL HIGH LOW LEVEL MIXING RATIOS OF 3 TO 4
G/KG. THERE REMAINS THAT CHANCE FOR THUNDER WITH THE
INSTABILITY...WHICH WOULD LEAD TO TEMPORARY VERY HEAVY PRECIP
RATES.
OVERALL THE INCREASING SUPPORT FOR MORE STEADY AND WIDESPREAD
PRECIP WILL SUPPORT DYNAMIC COOLING. THAT COUPLED WITH THE COOLING
FROM THE DIURNAL TREND AND SLIGHT COOL ADVECTION WILL WARRANT RAIN
CHANGING TO A MORE PREVALENT SNOW FROM WEST TO EAST ACROSS THE
ADVISORY AREA THIS EVENING...MAINLY PRIOR TO 10 PM. ALREADY
THROUGH BRIGHT BANDING AND DUAL-POL PRODUCTS THE MELTING LAYER IS
NOT FAR ALOFT AT ALL ACROSS THE ENTIRE AREA. THE TIMING OF
CHANGEOVER WILL DIRECTLY IMPACT HOW MUCH SNOW...AS SOME OF THE
HEAVIER RATES ARE FAVORED IN THE HOURS IMMEDIATELY AFTER CHANGE
OVER DUE TO MID-LEVEL FGEN AND INSTABILITY. THERE SHOULD BE A
TIGHT GRADIENT IN SNOWFALL THROUGH THIS EVENING...WITH AREAS ALONG
AND SOUTH OF INTERSTATE 80 NOT EXPECTED TO SEE ANY ACCUMULATION
BASICALLY...AND THAT DEMARCATION MAY EVEN BE FURTHER NORTH TOWARDS
THE U.S. HIGHWAY 34. HAVE GUIDED ON QPF CLOSE TO THE 12Z/18Z NAM
AND 09Z SREF...WITH RATIOS ADJUSTED QUITE LOW AND GRADUALLY
INCREASING TOWARDS 15 TO 1 TOWARDS ROCKFORD WHERE DENDRITIC GROWTH
LAYER IS DEEPER.
BY LATE EVENING INTO OVERNIGHT...THE SYSTEM 850 AND 700 MB LOWS
WILL PASS OVER /OR AT THEIR CLOSEST POINT TO/ THE AREA.
DEFORMATION IS INDICATED BY ALL GUIDANCE IN THIS TIME. PRECIP TYPE
WILL TRANSITION TO SNOW OVER ALMOST THE ENTIRE AREA...BUT THE
DEEPEST MOISTURE AND INSTABILITY/NEGATIVE EPV WILL GRADUALLY BE
WANING. THE TREND IN THE EC AND NAM/SREF HAS BEEN SLOWER WITH
REMOVING THE SYSTEM...WITH ALMOST A SECONDARY FLARE UP IN THE
MORNING AS THE POSITIVELY TILTED UPPER TROUGH SHIFTS EAST. SO HAVE
HELD ON TO ACCUMULATING SNOW LONGER...ESPECIALLY ACROSS CHICAGO
AND NORTHWEST IN. EVEN SOME LAKE ENHANCEMENT IS POSSIBLE LATE
TONIGHT INTO FRIDAY MORNING. AMOUNTS AFTER DAYBREAK OF AROUND ONE
INCH ARE EXPECTED IN FAR NORTHEAST IL INTO NORTHWEST IN...WHERE
SLIGHTLY HIGHER AMOUNTS MAY OCCUR.
STORM TOTAL SNOWFALL ACCUMULATIONS THROUGH FRIDAY MORNING ARE 4 TO
7 INCHES ACROSS MUCH OF THE ADVISORY AREA...OUTSIDE OF THE
SOUTHERN COUNTIES /I-80 CORRIDOR/ WHICH HAVE QUITE A TIGHT
GRADIENT IN TOTAL SNOWFALL FORECAST. ANY LOCATIONS THAT SEE SOME
OF THE PERSISTENT HEAVIER RATES...OR THUNDER SNOW...WILL END UP
HAVING HIGHER AMOUNTS ESPECIALLY DURING THIS EVENING. A SHORT FUSE
WINTER STORM WARNING MAY BE NEEDED FOR A WHILE IF THE BANDING IS A
PARTICULARLY STRONG AND STAGNANT SIGNATURE. WITH THE TIMING OF THE
HEAVIEST SNOW BEING AT THE TAIL END AND AFTER THE EVENING RUSH
HOUR...AND RATES GRADUALLY DIMINISHING DURING THE DAYBREAK
TIME...PUBLIC IMPACTS WOULD SEEM TO BE SLIGHTLY LOWER. SO CONTINUE
TO GO WITH THE ADVISORY AT THIS TIME.
MTF
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY...
320 PM...LIGHT SNOW OR SNOW SHOWERS LIKELY TO STILL BE ONGOING
FRIDAY EVENING AS THE LOW LIFTS NORTHEAST AND COLDER AIR ADVECTS
ACROSS THE AREA. EXPECT SNOW SHOWERS TO DECREASE IN COVERAGE AND
INTENSITY THROUGH THE NIGHT BUT STILL THE POTENTIAL FOR SOME
ADDITIONAL...THOUGH MINOR ACCUMULATION FRIDAY EVENING ESPECIALLY
ACROSS NORTHEAST IL INTO NORTHWEST INDIANA. WITH AT LEAST SOME
PARTIAL CLEARING IN ADDITION TO THE COLD AIR ADVECTION...EXPECT
TEMPS TO DIP INTO THE TEENS ACROSS NORTHWEST IL AND GIVEN THE
EXPECTED SNOWFALL TONIGHT...TEMPS COULD DROP EVEN FURTHER WITH
THE FRESH SNOWPACK.
THE WEEKEND IS LOOKING FAIRLY QUIET AS A LARGE RIDGE OF HIGH
PRESSURE BUILDS ACROSS THE REGION ON SATURDAY...SHIFTING EAST
SATURDAY NIGHT INTO SUNDAY. DESPITE SUNSHINE...AIRMASS REMAINS
FAIRLY COLD SATURDAY COMBINED WITH THE SNOWPACK...HIGHS MAY ONLY
REACH LOW/MID 30S. WITH LIGHT WINDS AND CLEAR SKIES...SHOULD SEE
A QUICK DROP IN TEMPS SATURDAY EVENING BUT WITH STRONG WARMING
ALOFT OVERNIGHT...TEMPS LIKELY TO BECOME STEADY OR EVEN BEGIN
RISING A FEW DEGREES OVERNIGHT INTO SUNDAY MORNING.
ANOTHER STORM SYSTEM THEN MOVES EAST ACROSS THE UPPER MIDWEST AND
NORTHERN LAKES SUNDAY AND SUNDAY NIGHT AND IT APPEARS THE BULK OF
THE PRECIP WITH THIS SYSTEM WILL REMAIN NORTH OF THE CWA BUT AS A
WEAK COLD FRONT MOVES ACROSS THE AREA SUNDAY NIGHT...THERE COULD BE
A PASSING SNOW OR RAIN SHOWER SUNDAY NIGHT AND HAVE MAINTAINED LOW
CHANCE POPS DURING THIS TIME. WITH STRONG WARMING CONTINUING SUNDAY
AHEAD OF THIS STORM SYSTEM...DEWPOINTS RECOVER INTO THE LOWER 30S
AND DESPITE THE SNOWPACK...TEMPS HAVE THE POTENTIAL TO WARM INTO
THE 40S...PERHAPS EVEN WARMER SOUTH OF WHEREVER THE MORE
SIGNIFICANT SNOW PACK ENDS UP FALLING OVER THE NEXT DAY.
THEN COMES NEXT WEEK AND THE POTENTIAL FOR ANOTHER SIMILAR STORM
TO THE ONE TO AFFECT THE AREA TONIGHT. MODELS DIFFER ON THE OVERALL
TIMING/PROGRESSION OF THIS STORM SYSTEM WITH THE ECMWF MUCH DEEPER
AND SLOWER WITH THE LOW NOT MOVING EAST ACROSS THE AREA UNTIL
WEDNESDAY AFTERNOON...WHICH IS MUCH SLOWER THAN THE WEAKER/FASTER
GFS. APPEARS LOW LEVELS WILL BE WARM ENOUGH TO SUPPORT ALL RAIN
UNTIL THE LOW MOVES EAST WHEN PRECIP COULD QUICKLY CHANGE TO SNOW
BEFORE ENDING. TOO FAR OUT IN TIME FOR SPECIFICS AND ALSO KEPT
MENTION OF RAIN OR SNOW OVER MUCH OF THE NORTHERN CWA. CMS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 02Z...
* RAIN/DRIZZLE/GRAUPEL WILL CHANGE TO WET SNOW OVERNIGHT
* CIGS/VSBY LIKELY REMAIN IFR/LIFR THROUGH TONIGHT
* STEADY SNOW TAPERS OFF TO SCT`D SHSN BY MID MORNING FRIDAY
* CIGS/VSBYS TO STEADILY IMPROVE DURING THE DAY FRIDAY
* SHSN POSSIBLE AGAIN FRIDAY AFTERNOON
IZZI
//DISCUSSION...UPDATED 02Z...
SITUATION EVOLVING MORE SLOWLY THAN EARLIER ANTICIPATED AND HAVE
ONCE AGAIN DELAYED THE ONSET OF STEADIER SNOWFALL. RADAR/SATELLITE
TRENDS SHOW CONVECTIVEY ELEMENTS CONTINUING TO POP UP FROM CHGO
METRO SW TO UIN AREA...WITH REPORTS OF RA/SN/GS BEING RECEIVED
WITH THESE SHOWERS. UNTIL STEADIER HEAVIER DEFORMATION BAND
DEVELOPS OVER THE AREA AFTER MIDNIGHT...WOULD EXPECT TO CONTINUE
TO SEE OCNL SHRASNGS WITH PERIODIC DZ OUTSIDE OF THE SHOWERS.
STARTING TO SEE A MORE ORGANIZED FRONTOGENETIC BAND DEVELOP NEAR
THE QUAD CITIES INTO NW IL AND WOULD ANTICIPATE THIS BAND TO GROW
IN AREAL COVERAGE AND DEVELOP EAST TONIGHT...EVENTUALLY REACHING
CHICAGO METRO AREA AFTER MIDNIGHT. STILL ANTICIPATE A 4-6 HOUR
LONG PERIOD OF MODERATE TO HEAVY SNOW FOR CHICAGO...THOUGH NOW
APPEARS AS THOUGH THE MORE LIKELY TIMING IS LATE TONIGHT/EARLY
FRIDAY MORNING.
IZZI
UPDATED 00Z...
MOST CONCENTRATE BAND OF FRONTOGENETICALLY DRIVEN RAIN/WET SNOW
HAS SHIFTED NORTH OF THE TERMINALS INTO FAR SOUTHERN WISCONSIN
WITH POCKETS OF PRIMARILY RAIN REMAINING OVER NORTHERN IL. HEAVIER
BURSTS OF PRECIP EARLY THIS EVENING COULD RESULT IN RAIN MIXING
WITH OR CHANGING TO WET SNOW...HOWEVER WATER VAPOR IMAGERY SHOWS
THE UPPER LOW STILL DIGGING SOUTHEAST INTO WESTERN IOWA EARLY THIS
EVENING. SHOULD SEE FORCING FROM THIS UPPER LOW RESULT IN INCREASE
IN COVERAGE/INTENSITY OF PRECIPITATION OVER NORTHERN ILLINOIS AS
THE EVENING WEARS ON. SUSPECT COOLING REQUIRED TO CAUSE A CHANGE
OVER TO WET SNOW WILL BE DRIVEN LARGELY BY DYNAMIC COOLING/ASCENT
AS THE UPPER LOW APPROACHES...SO THIS MAKES TIMING SOMEWHAT
TRICKY. TRENDS IN SHORT RANGE MODELS AS WELL AS SATELLITE IMAGERY
TEND TO SUPPORT A SLOWER CHANGE OVER TO ALL SNOW AND HAVE DELAYED
THE SWITCH-OVER ANOTHER HOUR WITH THE LATEST SET OF TAFS.
ONCE BAND OF MODERATE TO HEAVY SNOW DEVELOPS WOULD ANTICIPATE
SEEING A A GOOD 4-6 HOUR LONG PERIOD OF MODERATE TO HEAVY SNOW AT
THE CHGO METRO TERMINALS FROM LATE THIS EVENING THROUGH MUCH OF
THE OVERNIGHT HOURS. SLOWER MOVEMENT OF THE UPPER LOW ALSO
SUPPORTS HANGING ONTO THE HEAVIER/ACCUMULATING SNOW LATER INTO THE
NIGHT/EARLY MORNING FRIDAY. HAVE CONTINUED WITH IFR VSBY SNOW
THROUGH 14Z...BUT ACTUALLY WORRIED THAT THE SNOW COULD BE HEAVIER
EVEN INTO THE FIRST PART OF THE DAY WHEN MORNING TRAFFIC PICKS UP.
HAVE MAINTAINED TEMPO FOR +TSSN IN THE TAFS AS OBSERVATIONAL DATA
AND SPC MESOANALYSIS DATA CONTINUE TO SUGGEST THE PRESENCE OF WEAK
INSTABILITY WHICH COMBINED WITH STRONG FORCING WOULD SEEM TO
SUPPORT THE THREAT OF EMBEDDED THUNDERSTORMS DEVELOPING OVERNIGHT.
STEADY SYSTEM SNOWS ARE LIKELY TO END EARLY/MID MORNING FRIDAY BUT
CYCLONIC LOW LEVEL FLOW...DEEP MOISTURE...AND EXCEPTIONALLY STEEP
LAPSE RATES WOULD SUPPORT THE CONTINUATION OF SNOW SHOWERS THROUGH
THE DAY FRIDAY. WHILE HAVE ONLY HAVE ONLY VFR SHSN IN THE TAFS FOR
NOW...POTENTIAL EXISTS FOR PERIODIC IFR VSBYS WITH ANY HEAVIER
SNOW SHOWERS FRIDAY AFTERNOON. WILL TAKE A CLOSER LOOK AT THIS
POTENTIAL WITH LATER TAF ISSUANCES.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 02Z...
* HIGH CONFIDENCE IN SWITCH OVER TO HEAVY WET SNOW...MEDIUM
CONFIDENCE ON TIMING
* LOW CONFIDENCE ON THUNDERSTORM POTENTIAL
* MEDIUM-HIGH CONFIDENCE ON ACCUMULATING SNOW LINGERING INTO EARLY
FRIDAY MORNING
* MEDIUM CONFIDENCE ON SHSN POTENTIAL FRIDAY AFTERNOON
IZZI
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
SATURDAY...VFR.
SUNDAY...SLIGHT CHANCE OF SHOWERS...OTHERWISE VFR.
MONDAY...VFR.
TUESDAY...CHANCE FOR RAIN/SNOW...POSSIBLE MVFR.
WEDNESDAY...CHANCE FOR RAIN...POSSIBLE MVFR.
RODRIGUEZ
&&
.MARINE...
116 PM CST
AN ACTIVE WEATHER PATTERN IS IN STORE FOR THE NEXT SEVERAL DAYS.
LOW PRESSURE WILL DEEPEN AS IT MOVES FROM SOUTHERN MISSOURI THIS
AFTERNOON TO THE EASTERN LAKES FRIDAY AFTERNOON. WINDS WILL BACK
FROM EAST TO NORTHWEST AND STRENGTHEN OVER LAKE MICHIGAN. SOME
GALE FORCE GUSTS ARE POSSIBLE OVER SOUTHERN LAKE MICHIGAN FRIDAY
MORNING...BUT FEEL IT WILL BE A SHORT DURATION EVENT AND WILL HOLD
OFF ON GALE HEADLINES FOR NOW. WILL CONTINUE WITH SMALL CRAFT
ADVISORY FOR THE IL AND IN NEARSHORE AREA. A RIDGE OF HIGH
PRESSURE WILL MOVE ACROSS LAKE MICHIGAN SATURDAY NIGHT BEFORE
ANOTHER LOW PRESSURE APPROACHES SUNDAY AND SUNDAY NIGHT. THIS LOW
WILL TAKE A PATH FURTHER NORTH FROM THE NORTHERN PLAINS TO LAKE
SUPERIOR...GENERATING MODERATELY STRONG SOUTHWEST FLOW OVER LAKE
MICHIGAN. THE NEXT STORM SYSTEM WILL MOVE ACROSS IL AND IN AROUND
WEDNESDAY.
ALLSOPP
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ006-ILZ013-ILZ014-ILZ022 UNTIL 9 AM
FRIDAY.
WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ019-ILZ020 UNTIL 6 AM FRIDAY.
IN...WINTER WEATHER ADVISORY...INZ001-INZ002 UNTIL 9 AM FRIDAY.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 4 PM FRIDAY.
SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1221 PM CST WED FEB 22 2012
.UPDATE...
MODELS...ESPECIALLY THE GFS CONTINUE TO SHOW A SIGNIFCANT SHIFT
WITH UPCOMING SYSTEM WITH LARGE IMPACTS FOR THE FORECAST AREA. NAM
CONTINUES TO BE FARTHER NORTH WITH THE EURO SOLUTION FARTHER
SOUTH. GFS IS FOR NOW SPLITTING THE DIFFERENCE AND ANTICIPATING
THE ARRIVAL OF THE 12Z EURO SHORTLY. STRONG FORCING WILL BEGIN
OVERNIGHT AS WARM ADVECTION INCREASES WITH STRONG MID LEVEL
FRONTOGENSIS CONTINUING INTO NORTHERN IOWA ON THURSDAY. SOME
INSTABILITY IS ALSO PRESENT IN THE CROSS SECTIONS AND MAY SEE
BANDED SNOWFALL WITH MOST LIKELY TIME FRAME FROM TOWARD SUNRISE ON
THURSDAY MORNING INTO MIDDAY THURSDAY. HAVE GONE AHEAD WITH WINTER
STORM WATCH ACROSS NORTHERN IOWA...ALONG AND NORTH OF AN TAMA-
WESTER CITY TO POCAHONTAS LINE FROM 09Z TONIGHT THROUGH THE DAY ON
THURSDAY. AMOUNTS AT THIS TIME LOOK TO BE 4 TO 8 INCHES WITH
HIGHEST AMOUNTS NEAR THE MINNESOTA BORDER. IF BANDING DOES
OCCUR...HEAVY AMOUNTS WILL LIKELY RESULT. THERE WILL LIKELY BE A
SHARP GRADIENT ON THE SOUTHERN EDGE OF THE SNOWFALL THEREFORE HAVE
BEEN SOMEWHAT LIBERAL ON INCLUDING COUNTIES ON SOUTHERN EDGE OF
THE WATCH AS MODELS STILL QUITE SPREAD ON THEIR SOLUTIONS.
&&
.PREV DISCUSSION... /ISSUED 540 AM CST WED FEB 22 2012/
UPDATED 22/12Z AVIATION DISCUSSION...
SHORT TERM /TODAY/...
TODAYS FORECAST IS RATHER COMPLEX AND IT DOESNT HELP THAT THE
MODELS ARE NOT HANDLING THE FINE DETAILS WELL AT ALL. A PRETTY WEAK
VORT MAX MOVED ACROSS THE FORECAST AREA DURING THE OVERNIGHT AND
THAT WAS ENOUGH TO PRODUCE SOME VERY LIGHT RAIN AND AREAS OF
DRIZZLE. CLEARLY THERE IS MORE MOISTURE IN THE ATMOSPHERE THAN THE
MODELS ARE SUGGESTING. LOOKING UPSTREAM ON WATER VAPOR OVERLAID
WITH RUC 500MB VORTICITY...THERE IS ANOTHER VORT MAX PROGGED TO PUSH
ACROSS THE FORECAST AREA BETWEEN 12 AND 15Z. NAM12 TIME HEIGHT
CROSS SECTIONS SHOW THE WEAK LIFT COMING ACROSS AREA HOWEVER IT
SHOWS SOME DRY LOW LEVEL AIR. HOWEVER...IT DID A POOR JOB WITH
MOISTURE WITH THE LAST VORT MAX SO I HAVE TO BELIEVE IT IS NOT
CAPTURING THE DEPTH OF MOISTURE WELL FOR THIS NEXT SHOT. FOR THAT
REASON I HAVE PUT A SLIGHT CHANCE OF RAIN WITH AREAS OF DRIZZLE
ALONG THE EXPECTED PATH OF THIS NEXT VORT MAX.
TAKING A LOOK AT TEMPS...THEY ARE ALL OVER THE PLACE. IN PART DUE
TO CLOUD COVER AND IN PART DUE TO SOME LOW LEVEL WINDS THAT ARE MORE
SOUTH SOUTHWEST THAN WEST. THE PROBLEM IS THAT TEMPS CURRENTLY ARE
HOVERING RIGHT AT OR JUST BELOW FREEZING. I EXPECT LITTLE TEMP
CHANGE BETWEEN NOW AND 12-13Z OR MAYBE A DROP OF A DEGREE OR TWO.
WITH MOISTURE IN PLACE AND WEAK LIFT AND TEMPS HOVERING AT OR JUST
BELOW FREEZING I HAD TO PUT A MENTION OF FREEZING DRIZZLE IN THE
FORECAST ON THE NORTHERN FRINGE OF THE PATH OF THE NEXT SHOT OF
VORTICITY COMING AT US. I EXPECT THIS ALL TO OCCUR THIS MORNING
YET.
FOR THE REST OF TODAY WE ARE SORT OF IN LIMBO WAITING FOR THE NEXT
SYSTEM TO MOVE IN TONIGHT. I EXPECT TO SEE A FAIR AMOUNT OF MID AND
HIGH LEVEL CLOUD COVER TODAY THEN GRADUALLY MOISTENING UP AS THE
AFTERNOON PROGRESSES. AT THIS POINT I REALLY DON/T SEE MUCH IN THE
WAY OF PRECIP FOR THE AFTERNOON BUT AS MOISTEN UP AHEAD OF THE
SYSTEM TONIGHT...I THINK WE WILL SEE SOME DRIZZLE ACROSS THE AREA.
FOR NOW I JUST HAVE IT ACROSS THE NORTH BUT POTENTIALLY COULD BE
MORE WIDESPREAD THAN THAT. SHOULD BE A FAIRLY MILD DAY AS WE MIX
SOME OF THE WARMER AIR ALOFT DOWN. I WENT A LITTLE AGGRESSIVE ON
THE WARM UP TODAY BUT WE WILL HAVE CLOUD COVER TODAY WHICH WILL
IMPACT THE WARM UP. IF WE HAVE A LOWER CLOUD DECK THAN WHAT I AM
THINKING THEN WE MAY BE TOO WARM. WE WILL NEED TO WATCH THAT.
LONG TERM /TONIGHT THROUGH WEDNESDAY/...
COMPLICATED FORECAST THIS EXTENDED PERIOD. A NUMBER OF FAST MOVING
WAVES IMPACTING THE REGION OVER THE NEXT 24 HOURS AND LITTLE MODEL
CONSENSUS ON TRACK AND PLACEMENT OF FEATURES. MODELS HAVING A
DIFFICULT TIME RESOLVING THE ENERGY AND THIS WILL MOST LIKELY RESULT
IN FURTHER REFINEMENT IN THE NEXT 1 TO 2 PACKAGES. FIRST WAVE
EXPECTED TO ARRIVE TONIGHT. NAM/GFS CONTINUE TO SHOW A MORE
NORTHERLY SOLUTION OVER NORTHERN IOWA FOR THE FIRST WAVE WHILE THE
GEM/EURO ARE TAKING THE ENERGY FARTHER SOUTH AND ACROSS NORTHERN
MISSOURI. WITH SOME COORDINATION CHALLENGES...HAVE OPTED TO BROAD
BRUSH THE REGION WITH CHANCE POPS...BUT WOULD HAVE PREFERRED TO
FOCUS MORE ON THE SOUTH FOR THE FIRST WAVE. THERMAL PROFILES AND SFC
TEMPERATURES POINT TO MOSTLY LIGHT SNOW NORTH AND A RAIN SNOW MIX
CENTRAL WITH SHOWERS SOUTH HALF. WITH THE SECOND AND STRONGER WAVE
IMPACTING THE AREA ON THURSDAY WHICH DEEPENS AND SLOWS AS IT CROSSES
THE REGION. THE AREA OF WARM AIR ADVECTION ALONG AND AHEAD OF IT IS
ALSO ACCOMPANIED BY AN AREA OF WEAK STABILITY...AND NEGATIVE EPV.
THOUGH IT LOOKS VERY PROBABLE THAT THE PRECIPITATION MAY BE
ACCOMPANIED BY THUNDER...THE LACK OF ANY CONSISTENCY IN TRACK THIS
MORNING MAKES IT DIFFICULT TO PLACE WHERE THIS MIGHT OCCUR. FOR
NOW...HAVE LEFT THE MENTION OUT OF THE FORECAST SO THE AREA CAN BE
BETTER REFINED LATER TODAY. NONE THE LESS...THE AREA WITH GREATER
LIFT IS LIKELY TO SEE SNOW OVERTAKE THE RAIN/SNOW MIX AS CONVECTION
ENHANCES THE PRODUCTION OF SNOW OVER RAIN SHOWERS. CURRENTLY AM
GOING TO GO WITH AN AREA BOUNDED BY JUST SOUTH OF I80 IN THE SOUTH
AND NEAR HIGHWAY 20 IN THE NORTH. WITH THE MIX MOST LIKELY FROM US
30 NORTH...THE HEAVIER SNOWFALL IS MAINLY EXPECTED BETWEEN US 30 AND
US 20 WHERE A BAND OF 1-3 MAY FALL. THIS BEARS WATCHING CLOSELY AND
WILL CAUTION ONCOMING SHIFT THAT FURTHER REFINEMENTS AND DETAIL WILL
BE NEEDED. NO HEADLINES PLANNED RIGHT NOW...AND WILL LET THE NEXT
SHIFT WORK THROUGH THE POSSIBILITY OF HEAVIER SNOW...IF THE NEWER
MODEL RUNS SHOW MORE CONSENSUS. AS THE LOW DEEPENS OVER THE
REGION...A SECONDARY H500 LOW WILL EXTEND BACK INTO CENTRAL IOWA
THURSDAY NIGHT AND LIKELY DROP ANOTHER 1 TO 2 INCHES OF SNOW OVER
THE NORTHEAST THIRD OF THE FORECAST AREA. PLAYING IT CONSERVATIVE
FOR NOW...DUE TO UNCERTAINTY WITH THE MODELS. COLD AIR AND LIGHT
SNOW AND FLURRIES WILL CONTINUE ON FRIDAY WITH LIGHT ACCUMULATIONS
POSSIBLE. BY SATURDAY A RIDGE WILL REPLACE THIS FIRST BATCH OF
ENERGY PRIOR TO THE LARGER SYSTEM APPROACHING FOR SUNDAY/MONDAY.
MODELS CONTINUE TO SHOW LITTLE OVERALL CONSENSUS YET...THOUGH THE
GEM/EURO HAVE SHOWN CONSISTENCY BETWEEN THESE TWO MODELS THE PAST
FEW RUNS. THE GFS IS STILL MUCH DEEPER...EARLIER...AND MAY BE TOO
QUICK TO ADVANCE THE ENERGY EAST AND WIND UP THE LOW. WITH THAT IN
MIND...HAVE BEEN LEANING TOWARD A WARMER SOLUTION FOR SUNDAY WITH
COORDINATION OF SURROUNDING OFFICES AND FAVORING RAIN SHOWERS FOR
NOW. STRONG COLD FRONT AND SNOW CHANCES RETURN SUNDAY NIGHT AS COLD
AIR WRAPS INTO THE SYSTEM. THE REAL SNOW SHOULD FALL WELL NORTHWEST
OF US IN THE DAKOTAS AND MINNESOTA BASED ON ALL THREE MED RANGE
MODELS WHICH ARE NOW BACKING THE LOW NORTHWEST WITH TIME. MUCH
COLDER AIR RETURNS FOR MONDAY AND TUESDAY WITH SOME RECOVERY BY
WEDNESDAY.
AVIATION DISCUSSION...22/18Z
RELATIVELY QUIET WEATHER THIS AFTERNOON WITH AS FIRST SHORT WAVE
PULLS TO THE EAST. THEREFORE...GENERALLY VFR CONDITIONS ARE
EXPECTED AT THE TAF SITES. ONLY EXCEPTIONS IS SOME NARROW BAND OF
STRATUS NEAR KMCW. OTHERWISE...WILL SEE INCREASING CLOUDS THIS
EVENING AHEAD OF THE APPROACHING SHORTWAVE WITH PCPN DEVELOPING
TOWARD MIDNIGHT AS WAA INTENSIFIES. RAIN IS EXPECTED PRIMARILY
SOUTH OF KFOD TO KALO LINE WITH RAIN CHANGING TO SNOW FARTHER
NORTH. THE PRECIPITATION WILL PERSIST ACROSS NORTHERN IOWA INTO
THURSDAY MORNING WITH WIDESPREAD IFR CONDITIONS AT KMCW AND
POSSIBLY KFOD AND KALO AS WELL. SURFACE WINDS WILL BECOME
SOUTHEAST TONIGHT SWITCHING TO THE NORTHWEST AND INCREASING ON
THURSDAY MORNING.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH THURSDAY AFTERNOON
FOR BLACK HAWK-BREMER-BUTLER-CERRO GORDO-EMMET-FRANKLIN-GRUNDY-
HAMILTON-HANCOCK-HARDIN-HUMBOLDT-KOSSUTH-PALO ALTO-POCAHONTAS-
TAMA-WEBSTER-WINNEBAGO-WORTH-WRIGHT.
&&
$$
.SHORT TERM UPDATE...COGIL
.LONG TERM...REV
.AVIATION...COGIL
AREA FORECAST DISCUSSION...UPDATED
NWS DES MOINES IA
540 AM CST WED FEB 22 2012
.UPDATED 22/12Z AVIATION DISCUSSION...
.SHORT TERM /TODAY/...
TODAYS FORECAST IS RATHER COMPLEX AND IT DOESNT HELP THAT THE
MODELS ARE NOT HANDLING THE FINE DETAILS WELL AT ALL. A PRETTY WEAK
VORT MAX MOVED ACROSS THE FORECAST AREA DURING THE OVERNIGHT AND
THAT WAS ENOUGH TO PRODUCE SOME VERY LIGHT RAIN AND AREAS OF
DRIZZLE. CLEARLY THERE IS MORE MOISTURE IN THE ATMOSPHERE THAN THE
MODELS ARE SUGGESTING. LOOKING UPSTREAM ON WATER VAPOR OVERLAID
WITH RUC 500MB VORTICITY...THERE IS ANOTHER VORT MAX PROGGED TO PUSH
ACROSS THE FORECAST AREA BETWEEN 12 AND 15Z. NAM12 TIME HEIGHT
CROSS SECTIONS SHOW THE WEAK LIFT COMING ACROSS AREA HOWEVER IT
SHOWS SOME DRY LOW LEVEL AIR. HOWEVER...IT DID A POOR JOB WITH
MOISTURE WITH THE LAST VORT MAX SO I HAVE TO BELIEVE IT IS NOT
CAPTURING THE DEPTH OF MOISTURE WELL FOR THIS NEXT SHOT. FOR THAT
REASON I HAVE PUT A SLIGHT CHANCE OF RAIN WITH AREAS OF DRIZZLE
ALONG THE EXPECTED PATH OF THIS NEXT VORT MAX.
TAKING A LOOK AT TEMPS...THEY ARE ALL OVER THE PLACE. IN PART DUE
TO CLOUD COVER AND IN PART DUE TO SOME LOW LEVEL WINDS THAT ARE MORE
SOUTH SOUTHWEST THAN WEST. THE PROBLEM IS THAT TEMPS CURRENTLY ARE
HOVERING RIGHT AT OR JUST BELOW FREEZING. I EXPECT LITTLE TEMP
CHANGE BETWEEN NOW AND 12-13Z OR MAYBE A DROP OF A DEGREE OR TWO.
WITH MOISTURE IN PLACE AND WEAK LIFT AND TEMPS HOVERING AT OR JUST
BELOW FREEZING I HAD TO PUT A MENTION OF FREEZING DRIZZLE IN THE
FORECAST ON THE NORTHERN FRINGE OF THE PATH OF THE NEXT SHOT OF
VORTICITY COMING AT US. I EXPECT THIS ALL TO OCCUR THIS MORNING
YET.
FOR THE REST OF TODAY WE ARE SORT OF IN LIMBO WAITING FOR THE NEXT
SYSTEM TO MOVE IN TONIGHT. I EXPECT TO SEE A FAIR AMOUNT OF MID AND
HIGH LEVEL CLOUD COVER TODAY THEN GRADUALLY MOISTENING UP AS THE
AFTERNOON PROGRESSES. AT THIS POINT I REALLY DON/T SEE MUCH IN THE
WAY OF PRECIP FOR THE AFTERNOON BUT AS MOISTEN UP AHEAD OF THE
SYSTEM TONIGHT...I THINK WE WILL SEE SOME DRIZZLE ACROSS THE AREA.
FOR NOW I JUST HAVE IT ACROSS THE NORTH BUT POTENTIALLY COULD BE
MORE WIDESPREAD THAN THAT. SHOULD BE A FAIRLY MILD DAY AS WE MIX
SOME OF THE WARMER AIR ALOFT DOWN. I WENT A LITTLE AGGRESSIVE ON
THE WARM UP TODAY BUT WE WILL HAVE CLOUD COVER TODAY WHICH WILL
IMPACT THE WARM UP. IF WE HAVE A LOWER CLOUD DECK THAN WHAT I AM
THINKING THEN WE MAY BE TOO WARM. WE WILL NEED TO WATCH THAT.
.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
COMPLICATED FORECAST THIS EXTENDED PERIOD. A NUMBER OF FAST MOVING
WAVES IMPACTING THE REGION OVER THE NEXT 24 HOURS AND LITTLE MODEL
CONSENSUS ON TRACK AND PLACEMENT OF FEATURES. MODELS HAVING A
DIFFICULT TIME RESOLVING THE ENERGY AND THIS WILL MOST LIKELY RESULT
IN FURTHER REFINEMENT IN THE NEXT 1 TO 2 PACKAGES. FIRST WAVE
EXPECTED TO ARRIVE TONIGHT. NAM/GFS CONTINUE TO SHOW A MORE
NORTHERLY SOLUTION OVER NORTHERN IOWA FOR THE FIRST WAVE WHILE THE
GEM/EURO ARE TAKING THE ENERGY FARTHER SOUTH AND ACROSS NORTHERN
MISSOURI. WITH SOME COORDINATION CHALLENGES...HAVE OPTED TO BROAD
BRUSH THE REGION WITH CHANCE POPS...BUT WOULD HAVE PREFERRED TO
FOCUS MORE ON THE SOUTH FOR THE FIRST WAVE. THERMAL PROFILES AND SFC
TEMPERATURES POINT TO MOSTLY LIGHT SNOW NORTH AND A RAIN SNOW MIX
CENTRAL WITH SHOWERS SOUTH HALF. WITH THE SECOND AND STRONGER WAVE
IMPACTING THE AREA ON THURSDAY WHICH DEEPENS AND SLOWS AS IT CROSSES
THE REGION. THE AREA OF WARM AIR ADVECTION ALONG AND AHEAD OF IT IS
ALSO ACCOMPANIED BY AN AREA OF WEAK STABILITY...AND NEGATIVE EPV.
THOUGH IT LOOKS VERY PROBABLE THAT THE PRECIPITATION MAY BE
ACCOMPANIED BY THUNDER...THE LACK OF ANY CONSISTENCY IN TRACK THIS
MORNING MAKES IT DIFFICULT TO PLACE WHERE THIS MIGHT OCCUR. FOR
NOW...HAVE LEFT THE MENTION OUT OF THE FORECAST SO THE AREA CAN BE
BETTER REFINED LATER TODAY. NONE THE LESS...THE AREA WITH GREATER
LIFT IS LIKELY TO SEE SNOW OVERTAKE THE RAIN/SNOW MIX AS CONVECTION
ENHANCES THE PRODUCTION OF SNOW OVER RAIN SHOWERS. CURRENTLY AM
GOING TO GO WITH AN AREA BOUNDED BY JUST SOUTH OF I80 IN THE SOUTH
AND NEAR HIGHWAY 20 IN THE NORTH. WITH THE MIX MOST LIKELY FROM US
30 NORTH...THE HEAVIER SNOWFALL IS MAINLY EXPECTED BETWEEN US 30 AND
US 20 WHERE A BAND OF 1-3 MAY FALL. THIS BEARS WATCHING CLOSELY AND
WILL CAUTION ONCOMING SHIFT THAT FURTHER REFINEMENTS AND DETAIL WILL
BE NEEDED. NO HEADLINES PLANNED RIGHT NOW...AND WILL LET THE NEXT
SHIFT WORK THROUGH THE POSSIBILITY OF HEAVIER SNOW...IF THE NEWER
MODEL RUNS SHOW MORE CONSENSUS. AS THE LOW DEEPENS OVER THE
REGION...A SECONDARY H500 LOW WILL EXTEND BACK INTO CENTRAL IOWA
THURSDAY NIGHT AND LIKELY DROP ANOTHER 1 TO 2 INCHES OF SNOW OVER
THE NORTHEAST THIRD OF THE FORECAST AREA. PLAYING IT CONSERVATIVE
FOR NOW...DUE TO UNCERTAINTY WITH THE MODELS. COLD AIR AND LIGHT
SNOW AND FLURRIES WILL CONTINUE ON FRIDAY WITH LIGHT ACCUMULATIONS
POSSIBLE. BY SATURDAY A RIDGE WILL REPLACE THIS FIRST BATCH OF
ENERGY PRIOR TO THE LARGER SYSTEM APPROACHING FOR SUNDAY/MONDAY.
MODELS CONTINUE TO SHOW LITTLE OVERALL CONSENSUS YET...THOUGH THE
GEM/EURO HAVE SHOWN CONSISTENCY BETWEEN THESE TWO MODELS THE PAST
FEW RUNS. THE GFS IS STILL MUCH DEEPER...EARLIER...AND MAY BE TOO
QUICK TO ADVANCE THE ENERGY EAST AND WIND UP THE LOW. WITH THAT IN
MIND...HAVE BEEN LEANING TOWARD A WARMER SOLUTION FOR SUNDAY WITH
COORDINATION OF SURROUNDING OFFICES AND FAVORING RAIN SHOWERS FOR
NOW. STRONG COLD FRONT AND SNOW CHANCES RETURN SUNDAY NIGHT AS COLD
AIR WRAPS INTO THE SYSTEM. THE REAL SNOW SHOULD FALL WELL NORTHWEST
OF US IN THE DAKOTAS AND MINNESOTA BASED ON ALL THREE MED RANGE
MODELS WHICH ARE NOW BACKING THE LOW NORTHWEST WITH TIME. MUCH
COLDER AIR RETURNS FOR MONDAY AND TUESDAY WITH SOME RECOVERY BY
WEDNESDAY.
&&
.AVIATION DISCUSSION...22/12Z
A COUPLE OF UPPER LEVEL DISTURBANCES WILL PASS ACROSS THE TAF
LOCATIONS THROUGH THE FORECAST PERIOD. ONE DISTURBANCE WILL MOVE
THROUGH BY 18Z. THIS WILL BRING A POTENTIAL FOR LIGHT RAIN OR
DRIZZLE TO KDSM AND KOTM WITH PATCHY FREEZING DRIZZLE OR LIGHT SNOW
TO KALO AND KMCW WITH MAINLY DRIZZLE AND FOG ELSEWHERE. THE NEXT
DISTURBANCE WILL COME TONIGHT PRODUCING MVFR CIGS AND RAIN ACROSS
THE SOUTH WITH SNOW ACROSS THE NORTH.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...FAB
LONG TERM...REV
AVIATION...FAB
AREA FORECAST DISCUSSION
NWS DES MOINES IA
316 AM CST WED FEB 22 2012
.SHORT TERM /TODAY/...
TODAYS FORECAST IS RATHER COMPLEX AND IT DOESNT HELP THAT THE
MODELS ARE NOT HANDLING THE FINE DETAILS WELL AT ALL. A PRETTY WEAK
VORT MAX MOVED ACROSS THE FORECAST AREA DURING THE OVERNIGHT AND
THAT WAS ENOUGH TO PRODUCE SOME VERY LIGHT RAIN AND AREAS OF
DRIZZLE. CLEARLY THERE IS MORE MOISTURE IN THE ATMOSPHERE THAN THE
MODELS ARE SUGGESTING. LOOKING UPSTREAM ON WATER VAPOR OVERLAID
WITH RUC 500MB VORTICITY...THERE IS ANOTHER VORT MAX PROGGED TO PUSH
ACROSS THE FORECAST AREA BETWEEN 12 AND 15Z. NAM12 TIME HEIGHT
CROSS SECTIONS SHOW THE WEAK LIFT COMING ACROSS AREA HOWEVER IT
SHOWS SOME DRY LOW LEVEL AIR. HOWEVER...IT DID A POOR JOB WITH
MOISTURE WITH THE LAST VORT MAX SO I HAVE TO BELIEVE IT IS NOT
CAPTURING THE DEPTH OF MOISTURE WELL FOR THIS NEXT SHOT. FOR THAT
REASON I HAVE PUT A SLIGHT CHANCE OF RAIN WITH AREAS OF DRIZZLE
ALONG THE EXPECTED PATH OF THIS NEXT VORT MAX.
TAKING A LOOK AT TEMPS...THEY ARE ALL OVER THE PLACE. IN PART DUE
TO CLOUD COVER AND IN PART DUE TO SOME LOW LEVEL WINDS THAT ARE MORE
SOUTH SOUTHWEST THAN WEST. THE PROBLEM IS THAT TEMPS CURRENTLY ARE
HOVERING RIGHT AT OR JUST BELOW FREEZING. I EXPECT LITTLE TEMP
CHANGE BETWEEN NOW AND 12-13Z OR MAYBE A DROP OF A DEGREE OR TWO.
WITH MOISTURE IN PLACE AND WEAK LIFT AND TEMPS HOVERING AT OR JUST
BELOW FREEZING I HAD TO PUT A MENTION OF FREEZING DRIZZLE IN THE
FORECAST ON THE NORTHERN FRINGE OF THE PATH OF THE NEXT SHOT OF
VORTICITY COMING AT US. I EXPECT THIS ALL TO OCCUR THIS MORNING
YET.
FOR THE REST OF TODAY WE ARE SORT OF IN LIMBO WAITING FOR THE NEXT
SYSTEM TO MOVE IN TONIGHT. I EXPECT TO SEE A FAIR AMOUNT OF MID AND
HIGH LEVEL CLOUD COVER TODAY THEN GRADUALLY MOISTENING UP AS THE
AFTERNOON PROGRESSES. AT THIS POINT I REALLY DON/T SEE MUCH IN THE
WAY OF PRECIP FOR THE AFTERNOON BUT AS MOISTEN UP AHEAD OF THE
SYSTEM TONIGHT...I THINK WE WILL SEE SOME DRIZZLE ACROSS THE AREA.
FOR NOW I JUST HAVE IT ACROSS THE NORTH BUT POTENTIALLY COULD BE
MORE WIDESPREAD THAN THAT. SHOULD BE A FAIRLY MILD DAY AS WE MIX
SOME OF THE WARMER AIR ALOFT DOWN. I WENT A LITTLE AGGRESSIVE ON
THE WARM UP TODAY BUT WE WILL HAVE CLOUD COVER TODAY WHICH WILL
IMPACT THE WARM UP. IF WE HAVE A LOWER CLOUD DECK THAN WHAT I AM
THINKING THEN WE MAY BE TOO WARM. WE WILL NEED TO WATCH THAT.
.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
COMPLICATED FORECAST THIS EXTENDED PERIOD. A NUMBER OF FAST MOVING
WAVES IMPACTING THE REGION OVER THE NEXT 24 HOURS AND LITTLE MODEL
CONSENSUS ON TRACK AND PLACEMENT OF FEATURES. MODELS HAVING A
DIFFICULT TIME RESOLVING THE ENERGY AND THIS WILL MOST LIKELY RESULT
IN FURTHER REFINEMENT IN THE NEXT 1 TO 2 PACKAGES. FIRST WAVE
EXPECTED TO ARRIVE TONIGHT. NAM/GFS CONTINUE TO SHOW A MORE
NORTHERLY SOLUTION OVER NORTHERN IOWA FOR THE FIRST WAVE WHILE THE
GEM/EURO ARE TAKING THE ENERGY FARTHER SOUTH AND ACROSS NORTHERN
MISSOURI. WITH SOME COORDINATION CHALLENGES...HAVE OPTED TO BROAD
BRUSH THE REGION WITH CHANCE POPS...BUT WOULD HAVE PREFERRED TO
FOCUS MORE ON THE SOUTH FOR THE FIRST WAVE. THERMAL PROFILES AND SFC
TEMPERATURES POINT TO MOSTLY LIGHT SNOW NORTH AND A RAIN SNOW MIX
CENTRAL WITH SHOWERS SOUTH HALF. WITH THE SECOND AND STRONGER WAVE
IMPACTING THE AREA ON THURSDAY WHICH DEEPENS AND SLOWS AS IT CROSSES
THE REGION. THE AREA OF WARM AIR ADVECTION ALONG AND AHEAD OF IT IS
ALSO ACCOMPANIED BY AN AREA OF WEAK STABILITY...AND NEGATIVE EPV.
THOUGH IT LOOKS VERY PROBABLE THAT THE PRECIPITATION MAY BE
ACCOMPANIED BY THUNDER...THE LACK OF ANY CONSISTENCY IN TRACK THIS
MORNING MAKES IT DIFFICULT TO PLACE WHERE THIS MIGHT OCCUR. FOR
NOW...HAVE LEFT THE MENTION OUT OF THE FORECAST SO THE AREA CAN BE
BETTER REFINED LATER TODAY. NONE THE LESS...THE AREA WITH GREATER
LIFT IS LIKELY TO SEE SNOW OVERTAKE THE RAIN/SNOW MIX AS CONVECTION
ENHANCES THE PRODUCTION OF SNOW OVER RAIN SHOWERS. CURRENTLY AM
GOING TO GO WITH AN AREA BOUNDED BY JUST SOUTH OF I80 IN THE SOUTH
AND NEAR HIGHWAY 20 IN THE NORTH. WITH THE MIX MOST LIKELY FROM US
30 NORTH...THE HEAVIER SNOWFALL IS MAINLY EXPECTED BETWEEN US 30 AND
US 20 WHERE A BAND OF 1-3 MAY FALL. THIS BEARS WATCHING CLOSELY AND
WILL CAUTION ONCOMING SHIFT THAT FURTHER REFINEMENTS AND DETAIL WILL
BE NEEDED. NO HEADLINES PLANNED RIGHT NOW...AND WILL LET THE NEXT
SHIFT WORK THROUGH THE POSSIBILITY OF HEAVIER SNOW...IF THE NEWER
MODEL RUNS SHOW MORE CONSENSUS. AS THE LOW DEEPENS OVER THE
REGION...A SECONDARY H500 LOW WILL EXTEND BACK INTO CENTRAL IOWA
THURSDAY NIGHT AND LIKELY DROP ANOTHER 1 TO 2 INCHES OF SNOW OVER
THE NORTHEAST THIRD OF THE FORECAST AREA. PLAYING IT CONSERVATIVE
FOR NOW...DUE TO UNCERTAINTY WITH THE MODELS. COLD AIR AND LIGHT
SNOW AND FLURRIES WILL CONTINUE ON FRIDAY WITH LIGHT ACCUMULATIONS
POSSIBLE. BY SATURDAY A RIDGE WILL REPLACE THIS FIRST BATCH OF
ENERGY PRIOR TO THE LARGER SYSTEM APPROACHING FOR SUNDAY/MONDAY.
MODELS CONTINUE TO SHOW LITTLE OVERALL CONSENSUS YET...THOUGH THE
GEM/EURO HAVE SHOWN CONSISTENCY BETWEEN THESE TWO MODELS THE PAST
FEW RUNS. THE GFS IS STILL MUCH DEEPER...EARLIER...AND MAY BE TOO
QUICK TO ADVANCE THE ENERGY EAST AND WIND UP THE LOW. WITH THAT IN
MIND...HAVE BEEN LEANING TOWARD A WARMER SOLUTION FOR SUNDAY WITH
COORDINATION OF SURROUNDING OFFICES AND FAVORING RAIN SHOWERS FOR
NOW. STRONG COLD FRONT AND SNOW CHANCES RETURN SUNDAY NIGHT AS COLD
AIR WRAPS INTO THE SYSTEM. THE REAL SNOW SHOULD FALL WELL NORTHWEST
OF US IN THE DAKOTAS AND MINNESOTA BASED ON ALL THREE MED RANGE
MODELS WHICH ARE NOW BACKING THE LOW NORTHWEST WITH TIME. MUCH
COLDER AIR RETURNS FOR MONDAY AND TUESDAY WITH SOME RECOVERY BY
WEDNESDAY.
&&
.AVIATION DISCUSSION...22/06Z
SEVERAL PIECES OF UPPER LEVEL ENERGY WILL PASS ACROSS IOWA DURING
THE FORECAST PERIOD. POSSIBLE SPRINKLES OR SNOW FLURRIES OVERNIGHT
INTO EARLY WEDNESDAY MORNING WITH BRIEF LOCAL MVFR CIGS POSSIBLE.
THE STRONGEST PIECE OF ENERGY WILL ARRIVE LATE IN THE AFTERNOON AND
EVENING. EXPECT MVFR CIGS AND PRECIPITATION TO AFFECT ALL SITES FOR
THE END OF THE PERIOD. WINDS WILL BE LIGHT TONIGHT BECOMING WESTERLY
DURING THE DAY WEDNESDAY.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...FAB
LONG TERM...REV
AVIATION...DONAVON
AREA FORECAST DISCUSSION
NWS TOPEKA KS
511 PM CST THU FEB 23 2012
...AVIATION UPDATE...
.DISCUSSION...
SEE PREV DISCUSSION.
&&
.AVIATION...
THE 18Z NAM AND 21Z RUC CONTINUE TO SUGGEST SOME MVFR CIGS POSSIBLE
AT TOP AND FOE WITH 925 RH INCREASING ABOVE 90 PERCENT. MHK APPEARS
TO REMAIN JUST WEST OF THE LOWER CIGS. WITH SOME MODEL
CONSISTENCY...WILL INTRODUCE SOME CIGS AROUND 2500 FT. OTHERWISE
EXPECT WINDY CONDITIONS TO PERSIST DUE TO THE STRONG PRESSURE
GRADIENT. DEEP MIXING FRIDAY AFTERNOON SHOULD ALLOW GUTSY WINDS TO
CONTINUE.
WOLTERS
&&
.PREV DISCUSSION... /307 PM CST THU FEB 23 2012/
THURSDAY EVENING THROUGH FRIDAY...SECONDARY PRESSURE SURGE AND
SUBSIDENCE WILL PRODUCE THE STRONGEST WINDS ACROSS THE AREA THROUGH
THE EVENING HOURS WITH GUSTS AROUND 50 MPH EXPECTED. UPPER LOW NOW
ACROSS EASTERN NEBRASKA WILL PIVOT SE OVERNIGHT WITH SOME STRATUS
EXPECTED TO DROP INTO THE NORTHERN CWA OVERNIGHT BUT PRECIP SHOULD
BE LIMITED TO AREAS NEAR THE NEBRASKA BORDER OR NORTHWARD.
ANOTHER WINDY AND COOLER DAY IS EXPECTED FRIDAY WITH HIGHS IN THE
MID TO UPPER 40S EXPECTED AS ANY STRATUS SHOULD SCATTER OUT BY
AFTERNOON.
FRIDAY EVENING THROUGH THURSDAY...STRONG WINDS CHARACTERIZE THE
UPCOMING WEEKEND AS THE NEXT DEEPENING SURFACE TROF TRACKS ACROSS
WESTERN KANSAS. THE SYSTEM WILL PASS THROUGH DRY AS A STRENGTHENING
PRESSURE GRADIENT WILL INCREASE WIND SPEEDS SATURDAY AFTERNOON
THROUGH SUNDAY. IN ADDITION...WELL MIXED PROFILER SOUNDINGS SUGGEST
HIGHS TO BE IN THE LOWER 50S SATURDAY INTO THE UPPER 50S SUNDAY.
AS THE AFOREMENTIONED UPPER TROUGH LIFTS NORTHEAST ANOTHER
PROGRESSIVE NEGATIVELY TILTED TROUGH BUILDS OVER THE WESTERN
CONUS MONDAY INTO TUESDAY. THE CLOSED SURFACE LOW IS SHOWN TO DEEPEN
AS IT LIFTS NORTHEAST ACROSS THE CENTRAL PLAINS. AMPLE MOISTURE
PROVIDED FROM THE GULF WILL DEVELOP DECENT CHANCES FOR RAIN OR
SNOW OVER THE CWA. WHILE THE 12Z ECMWF IS FASTER THAN THE 12Z
GFS...BOTH MODELS SEEM TO BE FAIRLY AGGRESSIVE IN THE STRENGTH OF
THE SYSTEM AND THE DECENT QPF AMOUNTS. AT THIS TIME...SIDED MORE
WITH THE ECMWF WHICH PLACES AREAS SOUTH OF INTERSTATE 70 IN THE
UNSTABLE WARM SECTOR WITH MUCAPES VALUES NEAR 300 J/KG AND 60 KTS
OF 0-6 KM SHEAR. DECIDED TO INCLUDE ISOLATED THUNDER TUESDAY
AFTERNOON INTO THE EVENING HOURS FOR THESE PARTICULAR AREAS WHILE
NORTH OF INTERSTATE 70 IS DEPICTING A MIXTURE OF LIGHT RAIN OR
LIGHT SNOW. BY TUESDAY EVENING...COLDER AIR WRAPPING ON THE
BACKSIDE OF THE LOW SHOULD TRANSITION ALL PRECIP TO LIGHT SNOW
BEFORE THE SYSTEM EXITS WEDNESDAY MORNING. VARIABILITY IN TIMING
AND TRACK OF THIS SYSTEM BETWEEN THE MODELS IS LARGE AND YET TO BE
RESOLVED THIS MANY DAYS OUT.
BOWEN
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 9 PM CST THIS EVENING FOR KSZ011-012-024-026-
038>040-054>056-058-059.
WIND ADVISORY UNTIL 6 PM CST THIS EVENING FOR KSZ008>010-020>023-
034>037.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
329 AM CST WED FEB 22 2012
.DISCUSSION...
BREEZY SEVERAL DAYS AHEAD...WITH DAILY CHANGES IN TEMPERATURES QUITE
NOTICEABLE. SPECIFICS ON THESE VALUES AND HUMIDITY LEVELS TODAY ARE THE
MAIN CHALLENGES THROUGH THE LATE WEEK.
VERY STRONG JET AGAIN SAMPLED FROM THE BERING SEA AREA EAST INTO
CENTRAL BRITISH COLUMBIA THEN SOUTHEAST INTO WYOMING WITH SPEEDS OF
150-180KT. DEEP UPPER LOW WAS OVER THE WESTERN GREAT LAKES WITH A
FEW SHORTWAVES MOVING THROUGH THE MAIN JET. 0Z 850MB TEMPERATURES
RANGED FROM 1C AT KTOP TO 5C AT KDDC TO 14C AT KAMA. SLIGHTLY HIGHER
MOISTURE THROUGHOUT THE LOWER TROPOSPHERE WAS NOTED AT KLBF IN
COMPARISON TO KTOP. SCATTERED MID AND HIGH CLOUDS WERE MOVING
THROUGH KANSAS WITH TEMPS STILL IN THE UPPER 30S TO MIDDLE 40S AT
08Z.
WEST TO NORTHWEST FLOW TO AGAIN BE QUITE DEEP THROUGH THE DAYTIME
PERIODS...PROMOTING DEEP MIXING AND GUSTY WINDS. SURFACE LOW
PRESSURE WILL ORGANIZE IN THE NORTHERN PLAINS AHEAD OF A SHORTWAVE
TROF...WITH WEST TO SLIGHTLY NORTHWEST WINDS FOR TODAY. TRAJECTORIES
OF ABOVE THE FIRST FEW THOUSAND FEET WILL HAVE A NORTHERLY
COMPONENT...AND THE BETTER WESTERN NEBRASKA-AREA MOISTURE WILL
ADVECT INTO THE AREA...KEEPING DEWPOINTS FROM DROPPING TOO FAR. EVEN
TRIMMING GUIDANCE A FEW DEGREES KEEPS RELATIVE HUMIDITIES IN THE
UPPER 20S TO MIDDLE 30S FOR MOST LOCATIONS. WIND SPEEDS ALSO LOOK
MARGINAL AT BEST FOR RED FLAG CRITERIA...WITH BETTER CLOUD COVER
EXPECTED FOR THE AFTERNOON HELPING TO KEEP PERSISTENT GUSTS IN
CHECK. HAVE INCREASED THE HIGH TEMPERATURE GRADIENT A BIT GIVEN THE
SLIGHT VARIATION IN WEST TO NORTHWEST WINDS FROM SOUTHERN TO
NORTHEAST LOCATIONS. COLD FRONT WITH THE SHORTWAVE TO ARRIVE LATE
TONIGHT...WITH MID LEVEL BAROCLINICITY INCREASING AS THE SHORTWAVE
NEARS THURSDAY. STILL SOMEWHAT DRY MID-LOW LEVELS WILL KEEP PRECIP
AT BAY...WITH STRONG NORTHWEST WINDS BRINGING 850MB TEMPS SOME
10-12C COOLER THAN TODAY. DEEP-LAYER WINDS DONT APPEAR STRONG ENOUGH
FOR ADVISORY SPEEDS HOWEVER. AFTERNOON TEMPERATURES MAY BE RATHER
STEADY AND HAVE ADVERTISED SUCH IN THE FORECAST. 500MB TEMPS DROP TO
NEAR -34C BY THURSDAY NIGHT...WITH VERY DEEP MIXING PROGGED BY BOTH
GFS AND NAM FRIDAY AFTERNOON. SUSTAINED SPEEDS SHOULD REMAIN SHORT
OF ADVISORY LEVELS...BUT COULD SEE GUSTS BE A PROBLEM WITH GOOD
DOWNWARD MOTION AND LOTS OF SUN.
TRENDED DOWN LOWS FRIDAY NIGHT WITH WINDS FINALLY WEAKENING AND
UPPER RIDGE NEARING. SOUTH WINDS INCREASE FOR SATURDAY AND LIKELY
INTO MUCH OF SUNDAY AS THE NEXT UPPER TROF NEARS. SOME DIFFERENCES
TAKE SHAPE WITH FAST THIS SYSTEM WILL BE...BUT SOUTHWEST WINDS
SHOULD BE ADEQUATE TO PUSH HIGHS BACK INTO THE UPPER 50S FOR AT
LEAST SOUTHERN AND EASTERN AREAS BEFORE THE FRONT WOULD ARRIVE ON
THE FASTER GFS. MOISTURE MAY BE DEEP ENOUGH FOR LIGHT PRECIPITATION
SUNDAY NIGHT. KEPT CHANCE POPS IN FOR TUESDAY...BUT CONFIDENCE NOT
HIGH AS DISCREPANCIES INCREASE. AIRMASS COMING IN BEHIND THE
SUNDAY/SUNDAY NIGHT SYSTEM IS SOURCED FROM NORTHWEST CANADA...WITH
HIGHS AT LEAST SEVERAL DEGREES BELOW NORMAL A GOOD BET.
65
&&
.AVIATION...
THE 00Z NAM AND 03Z RUC FORECAST SOUNDINGS CONTINUE TO SHOW A STRONG
NOCTURNAL INVERSION OVERNIGHT AS LOW LEVEL WINDS INCREASE TO AROUND
40KTS. BECAUSE OF THIS WILL INCLUDE A MENTION OF WIND SHEER AROUND
1000FT FOR THE EARLY MORNING. BY WEDNESDAY AFTERNOON THE BOUNDARY
LAYER IS EXPECTED TO MIX OUT WITH DRY ADIABATIC LAPSE RATES. THIS
COULD ENCOURAGE SOME GUSTS DURING THE AFTERNOON. OTHERWISE DRY LOW
LEVELS OF THE ATMOSPHERE WILL ALLOW VFR CONDITIONS TO PREVAIL.
WOLTERS
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1105 PM CST TUE FEB 21 2012
...AVIATION UPDATE...
.DISCUSSION...
SEE PREV DISCUSSION.
&&
.AVIATION...
THE 00Z NAM AND 03Z RUC FORECAST SOUNDINGS CONTINUE TO SHOW A STRONG
NOCTURNAL INVERSION OVERNIGHT AS LOW LEVEL WINDS INCREASE TO AROUND
40KTS. BECAUSE OF THIS WILL INCLUDE A MENTION OF WIND SHEER AROUND
1000FT FOR THE EARLY MORNING. BY WEDNESDAY AFTERNOON THE BOUNDARY
LAYER IS EXPECTED TO MIX OUT WITH DRY ADIABATIC LAPSE RATES. THIS
COULD ENCOURAGE SOME GUSTS DURING THE AFTERNOON. OTHERWISE DRY LOW
LEVELS OF THE ATMOSPHERE WILL ALLOW VFR CONDITIONS TO PREVAIL.
WOLTERS
&&
.PREV DISCUSSION... /334 PM CST TUE FEB 21 2012/
WESTERLY FLOW IN THE MID LEVELS WILL CONTINUE THROUGH THE PERIOD. A
SHORTWAVE WILL DROP SOUTHWEST OUT OF THE PACIFIC NORTHWEST LATE
TONIGHT WITH INCREASE IN MID LEVEL MOISTURE SO EXPECT A MID CLOUD
DECK TO MOVE OVER AFTER MIDNIGHT THEN EXIT DURING THE MORNING HOURS
ON TUESDAY. AS ANOTHER WAVE MOVES ACROSS THE NORTHERN PLAINS ON
TUESDAY MORE CLOUDS WILL MOVE INTO THE FAR NORTHERN COUNTIES IN THE
AFTERNOON NEAR THE NEBRASKA BORDER.
TONIGHT THE WINDS WILL DROP OFF AFTER SUNSET AS THE WINDS DECOUPLE
IN THE BOUNDARY LAYER. THIS WILL ALLOW TEMPERATURES TO COOL INTO THE
LOW TO MID 30S.
ON TUESDAY...THE COMBINATION OF WESTERLY DOWNSLOPE FLOW...ABUNDANT
SUNSHINE AND MIXING DOWN FROM 800 MB WILL YIELD HIGHS IN THE LOW TO
MID 60S FOR MUCH OF THE AREA. WEST WINDS WILL GUST OVER 20 MPH IN
THE AFTERNOON.
53
NEXT SHORTWAVE TROUGH MOVING ACROSS THE NORTHERN PLAINS WEDNESDAY
NIGHT/THURSDAY WILL FOCUS PRECIP TO THE NORTH OF THE AREA WITH
STILL A DRY FCST FOR THIS PERIOD. HOWEVER...AFTER WESTERLY WINDS
MOST OF THE NIGHT...A FRONT WILL BEGIN TO TRAVERSE THE CWA LATE IN
THE NIGHT. THE TIMING OF THE FRONT WILL LIKELY BE TOO LATE TO HAVE
A LOT OF IMPACT ON LOW TEMPS...EXCEPT MAYBE THE FAR NORTH WHERE A
FEW READINGS IN THE MIDDLE 30S ARE EXPECTED. ELSEWHERE...TEMPS
EXPECTED TO REMAIN WELL ABOVE NORMAL WITH LOWS SOUTH OF I 70
GENERALLY 40 TO 43 DEGREES. THE AFFECTS OF THE COLDER AIR MOVING
INTO THE CWA BEHIND THE FRONT WILL BE FELT MORE DURING THE DAY
THURSDAY AS HIGH TEMPS TOP OUT IN THE UPPER 40S AND LOWER 50S...OR
ABOUT 10 TO 15 DEGREES COOLER THAN WEDNESDAY ALONG WITH A BLUSTERY
NORTHWEST.
THE COOLEST HIGHS STILL LOOK TO BE ON FRIDAY WHERE THE COOLER LOWS
IN THE 20S TO AROUND 30 WILL HELP TO LIMIT THE DAYTIME HIGHS TO THE
40S. THE UPPER LEVEL PATTERN INTO THE WEEKEND STILL SHOWS THE UPPER
LEVEL SHORTWAVE TROUGH OVER THE GREAT LAKES MOVING OFF THE EAST
COAST WITH ANOTHER STRONG UPPER TROUGH ADVANCING FROM THE PACIFIC
NORTHWEST AND INTO THE NORTHERN PLAINS BY SUNDAY. WARM AIR ADVECTION
AHEAD OF THIS SYSTEM OVER THE WEEKEND SHOULD PUSH HIGHS INTO THE
LOWER 50S IN MANY AREAS BEFORE THE NORTHERN PLAINS WAVE PUSHES
ANOTHER COLD FRONT ACROSS THE CWA SUNDAY NIGHT. THIS WILL PROVIDE
THE NEXT CHANCE FOR RAIN OR POSSIBLY SOME SNOW SUNDAY NIGHT AS THE
COLDER AIR OVERSPREADS THE AREA BEHIND THE FRONT.
THERE MAY THEN BE A BRIEF BREAK IN PRECIP CHANCES DURING THE DAY ON
MONDAY BEFORE ANOTHER SYSTEM APPROACHES THE CENTRAL PLAINS FROM THE
ROCKIES LATER MONDAY NIGHT INTO TUESDAY. IF THIS SCENARIO
HAPPENS...MORE COLD AIR WOULD ALREADY BE IN PLACE AHEAD OF IT AND
THEREFORE SNOW CHANCES WOULD BE A LITTLE HIGHER. IT IS DIFFICULT
THIS FAR OUT IN THIS PATTERN TO GO WITH AN ALL SNOW FORECAST FOR AN
EXTENDED PERIOD OF TIME. WILL GO WITH A LIGHT SNOW/RAIN SNOW MIX
MONDAY NIGHT AND TUESDAY FOR NOW WITH HIGHS TUESDAY IN THE 30S. 63
&&
.TOP WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1019 PM EST THU FEB 23 2012
.Update...
Issued at 1019 PM EST Feb 23 2012
Going to need to update the forecast quickly as convection is on the
rebound across our western sections. It appears that nocturnal
cooling is quickly eroding the elevated mix/warm layer and
convection is now being able to develop vertically with the
reduction in convective inhibition. Recent radar imagery reveals
showers and thunderstorms quickly developing west of I-65...but
still well out ahead of the surface frontal boundary. Storms do not
appear to be rooted in the surface layer...yet. Main threats look
to be gusty winds and possibly some large hail.
Updated products out shortly.
Update issued at 938 PM EST Feb 23 2012
Convection continues to rumble across our eastern sections this
evening. Parameters never really got in sync with each other to
produce a severe weather. We did have one decent storm that popped
across Bullitt county that produced a decent amount of dime sized
hail. Those storms have quickly moved to the northeast and are close
to exiting our Bluegrass counties. Other convection continues to
struggle across the eastern portions of south-central Kentucky.
Convection appears to be driven in large part by large scale ascent
ahead of an approaching trough axis. 00Z BNA sounding showed a very
deep mixed layer in the lower levels with some instability aloft.
Much of the activity across south-central KY appears to be elevated
as well.
Surface front is now pushing into western Kentucky. Some
development has recently popped up across northwest Tennessee near
Clarksville. Will be watching this activity as it is closer to the
better moisture and may eventually become rooted near the surface.
This activity...if it holds together would affect our far southern
counties over the next few hours. For now...have kept slight-chance
PoPs in the west with the highest PoPs in the east for the next few
hours. If convection to our southwest holds together, will need to
raise PoPs a bit more in the south. Overall threat of severe
weather looks greatly diminished...however any storm will be capable
of producing heavy rains, gusty winds, small hail, and cloud to
ground lightning.
Updated forecast and text products are already out.
Update issued at 635 PM EST Feb 23 2012
Did a quick update to the forecast to account for the batch of
convection that fired up east of I-65 and will affect the Bluegrass
region early this evening. Elsewhere, lowered PoPs slightly for the
next few hours and then ramped them back up as the frontal boundary
to the west swings through the region.
It appears that we`re in a waiting game this evening with regards to
the severe weather threat. Initial batch of convection fired just
west of I-65 late this afternoon. However, strong moisture
convergence and theta-e advection appears to have spawn the
convective cluster that is currently moving through the Bluegrass
region.
Looking at the mesoscale analysis...it appears that several
variables are present which are limiting our convective potential at
the present time. First...the strong mid-level westerly flow has
prevent moisture transport northward from the south. While the
models indicated that mid-50s dewpoints would advect north...that
has not happened...yet. Secondly, ACARS soundings out of SDF this
afternoon reveal an elevated mixed layer which has led to increasing
values of convective inhibition...generally across the south and
western sections of the forecast area. Convection across the
Bluegrass is not rooted at the surface...but appears to be elevated
in nature. The strong westerly flow has also resulted in bulk shear
values of over 70kts. Vertical and 3-D analysis of the radar data
with the initial storms indicated that the shear was tilting the
updrafts quite a bit to the NE with increasing height.
While it appears that we may be entering a relative minimum in
convective coverage, recent observations do show moisture pooling
out ahead of the surface cold frontal boundary which is still west
of the Wabash and Mississippi Rivers. Quality moisture is still
lacking, but dewpoints are getting into the mid 50s. With the onset
of nocturnal cooling...I believe that this elevated mixed/warm layer
will likely mix out. This perhaps may be already occurring to the
west as inhibition is weakening quickly to the west and CAPE values
have increased a bit according to the latest SPC mesoanalysis.
I believe that we still have a window of opportunity for convection
this evening as the front pushes into the region. The HRRR and
other high resolution models appear to have backed off convection
slightly. However, these models have a history of being a bit too
pessimistic with convection in the past. The other thing we have
noted is that the surface winds have started to shift back to
southwest in areas to our west. This will likely result in a
lowering of storm-relative helicity and may result in a lesser
threat for updrafts to obtain or sustain rotation. Will continue to
monitor things closely over the next couple of hours and amend the
forecast as required.
.Short Term (Tonight through Friday night)...
Updated at 300 PM EST Feb 23 2012
...Severe Weather Possible Through This Evening...
As of 20Z, a 990 mb surface low was over central Missouri, and its
associated warm front extended eastward across Kentucky. Starting
to see more of a cloud band coinciding with the east-west pressure
trough and wind shift. A fairly extensive cu field centered on the
confluence of the Wabash and Ohio Rivers seems to be the most likely
point to initiate severe convection in the next few hours.
SPC continues to advertise a slight risk, with a better than 30%
chance for severe wind gusts centered on the Ohio River. Tornado
probabilities have been lowered, but there is still concern
especially north of the boundary, where helicity is enhanced due to
the SE surface winds.
Temperatures have warmed sufficiently even north of the boundary
that the instability is there. However the low-level moisture return
has been slower to arrive, so we will have only a narrow window to
initiate storms late this afternoon. Worst weather is still expected
from roughly 22Z through 03Z, and at this point it is largely a
waiting game for convective initiation. Damaging winds, large hail,
and isolated tornadoes are all still in play.
Cold pool associated with the upper trof and low-level cold
advection will make for a chilly and raw Friday. Will maintain a low
overcast, with the chance for light rain especially in the northern
counties. POPs will range from a dry forecast south of the
Parkways...to a low-end chance in southern Indiana, and QPF will be
quite low. Tight pressure gradient behind the exiting low, and
efficient mixing will keep sustained winds at 15-25 mph with a few
gusts over 35 mph. Expect a very minimal recovery in temps, with
highs barely cracking 50 in the south. Lows Friday night will dip
into the upper 20s, which is actually just a couple degrees below
normal for this time of year. Expect a few flurries late in the
evening as the cold air finally arrives, but not looking for any
snow accumulation at all and will not mention a measurable POP.
.Long Term (Saturday through Thursday)...
Updated at 300 PM EST Feb 23 2012
Sat/Sun/Mon we`ll sit in a quiet weather period with temperatures
steadily increasing each day. Sfc high pressure will be in control
Sat/Sun with return flow beginning on Monday. Zonal flow aloft will
dominate Sat-Mon. While high temps will only be in the lower 40s
Sat, they should increase to the 50s for Sun/Mon. Low temps will be
in the mid 20s Sat night, but mid to upper 30s for Sun/Mon nights.
By Mon night, a strong upper level trough will drop south into the
Rockies creating lee side sfc cyclogenesis sometime early next
week. Models vary on the timing and sfc low/front evolution, but
generally it looks like the upper trough will push east into the
Midwest by Wed/Thurs with a sfc low pushing through the upper
Midwest. Ahead of this system, isentropic lift and very subtle
upper level waves passing through the region will begin Monday night
allowing for a 20% chance of rain showers over south central KY.
Lift and moisture return will continue to increase Tues combined
with weak upper level waves justifying an increase in POPs over the
entire area. Tues night or early Wed, the cold front or a warm
front and cold front (depending on which model soln you buy) will
cross the region causing showers and thunderstorms. There is still
quite a bit of discrepancy in the model sfc feature solns and so did
not make big changes to this forecast. As previously mentioned,
high temps for Tues/Wed will likely be warmer than what`s currently
in the forecast especially if we get a good warm surge ahead the
cold front. Will continue mid 50s to around 60 for highs Tues/Wed
until more certainty can be achieved.
Wed night/Thurs, precip should move east of the area with sfc high
pressure settling in again. High temps will cool back into the mid
40s to around 50.
&&
.Aviation (00Z TAF Issuance)...
Updated at 615 PM EST Feb 23 2012
East-west surface warm frontal boundary is currently located along
and just north of I-64. Pocket of enhanced theta-e advection
combined with strong moisture convergence seems to whats driving
initial batch of convection moving across east-central Kentucky.
Surface low still remains out towards the STL area with a surface
cold front extending southwestward. Frontal boundary has yet to
cross the Wabash or Mississippi Rivers. This front is forecast to
swing eastward through the region tonight bringing a chance of
additional convection to the region.
For KLEX...initial batch of convection will affect the terminal
early in the forecast period. There will likely be a break in the
precipitation after 24/01Z but some additional development to the
west may swing through later on. For now will keep VCSH in the
forecast through 24/08Z while keeping conditions VFR. Winds will
remain out of the southwest and then shift to the west by 24/14Z and
remain quite gusty during the day on Friday.
For KSDF...initial batch of convection developed just east of the
terminal. With the frontal boundary out to the west...expect
additional development to take place this evening with the best time
for convection between 24/00-04Z. Most precipitation should be out
of the terminal by 24/07Z. Southwest winds are likely this evening
and into the overnight hours before shifting to the west by 24/14Z.
Winds are likely to be quite strong on Friday with sustained 15-20kt
and gusts up 30kts being possible.
For KBWG...Plan on keeping VCTS in the TAF through 24/04Z as frontal
boundary remains to the west and will be pushing through. Feel that
precipitation will be east of the terminal by 24/06Z with VFR
conditions prevailing. Southwest winds of 8-14kts can be expected
this evening with a shift to the west occurring late tonight and
early Friday morning. West winds of 15-20kts with gusts of 25-30kts
will be possible during the day on Friday.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........MJ
Short Term.......RAS
Long Term........AMS
Aviation.........MJ
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
939 PM EST THU FEB 23 2012
.Update...
Issued at 938 PM EST Feb 23 2012
Convection continues to rumble across our eastern sections this
evening. Parameters never really got in sync with each other to
produce a severe weather. We did have one decent storm that popped
across Bullitt county that produced a decent amount of dime sized
hail. Those storms have quickly moved to the northeast and are close
to exiting our Bluegrass counties. Other convection continues to
struggle across the eastern portions of south-central Kentucky.
Convection appears to be driven in large part by large scale ascent
ahead of an approaching trough axis. 00Z BNA sounding showed a very
deep mixed layer in the lower levels with some instability aloft.
Much of the activity across south-central KY appears to be elevated
as well.
Surface front is now pushing into western Kentucky. Some
development has recently popped up across northwest Tennessee near
Clarksville. Will be watching this activity as it is closer to the
better moisture and may eventually become rooted near the surface.
This activity...if it holds together would affect our far southern
counties over the next few hours. For now...have kept slight-chance
PoPs in the west with the highest PoPs in the east for the next few
hours. If convection to our southwest holds together, will need to
raise PoPs a bit more in the south. Overall threat of severe
weather looks greatly diminished...however any storm will be capable
of producing heavy rains, gusty winds, small hail, and cloud to
ground lightning.
Updated forecast and text products are already out.
Update issued at 635 PM EST Feb 23 2012
Did a quick update to the forecast to account for the batch of
convection that fired up east of I-65 and will affect the Bluegrass
region early this evening. Elsewhere, lowered PoPs slightly for the
next few hours and then ramped them back up as the frontal boundary
to the west swings through the region.
It appears that we`re in a waiting game this evening with regards to
the severe weather threat. Initial batch of convection fired just
west of I-65 late this afternoon. However, strong moisture
convergence and theta-e advection appears to have spawn the
convective cluster that is currently moving through the Bluegrass
region.
Looking at the mesoscale analysis...it appears that several
variables are present which are limiting our convective potential at
the present time. First...the strong mid-level westerly flow has
prevent moisture transport northward from the south. While the
models indicated that mid-50s dewpoints would advect north...that
has not happened...yet. Secondly, ACARS soundings out of SDF this
afternoon reveal an elevated mixed layer which has led to increasing
values of convective inhibition...generally across the south and
western sections of the forecast area. Convection across the
Bluegrass is not rooted at the surface...but appears to be elevated
in nature. The strong westerly flow has also resulted in bulk shear
values of over 70kts. Vertical and 3-D analysis of the radar data
with the initial storms indicated that the shear was tilting the
updrafts quite a bit to the NE with increasing height.
While it appears that we may be entering a relative minimum in
convective coverage, recent observations do show moisture pooling
out ahead of the surface cold frontal boundary which is still west
of the Wabash and Mississippi Rivers. Quality moisture is still
lacking, but dewpoints are getting into the mid 50s. With the onset
of nocturnal cooling...I believe that this elevated mixed/warm layer
will likely mix out. This perhaps may be already occurring to the
west as inhibition is weakening quickly to the west and CAPE values
have increased a bit according to the latest SPC mesoanalysis.
I believe that we still have a window of opportunity for convection
this evening as the front pushes into the region. The HRRR and
other high resolution models appear to have backed off convection
slightly. However, these models have a history of being a bit too
pessimistic with convection in the past. The other thing we have
noted is that the surface winds have started to shift back to
southwest in areas to our west. This will likely result in a
lowering of storm-relative helicity and may result in a lesser
threat for updrafts to obtain or sustain rotation. Will continue to
monitor things closely over the next couple of hours and amend the
forecast as required.
.Short Term (Tonight through Friday night)...
Updated at 300 PM EST Feb 23 2012
...Severe Weather Possible Through This Evening...
As of 20Z, a 990 mb surface low was over central Missouri, and its
associated warm front extended eastward across Kentucky. Starting
to see more of a cloud band coinciding with the east-west pressure
trough and wind shift. A fairly extensive cu field centered on the
confluence of the Wabash and Ohio Rivers seems to be the most likely
point to initiate severe convection in the next few hours.
SPC continues to advertise a slight risk, with a better than 30%
chance for severe wind gusts centered on the Ohio River. Tornado
probabilities have been lowered, but there is still concern
especially north of the boundary, where helicity is enhanced due to
the SE surface winds.
Temperatures have warmed sufficiently even north of the boundary
that the instability is there. However the low-level moisture return
has been slower to arrive, so we will have only a narrow window to
initiate storms late this afternoon. Worst weather is still expected
from roughly 22Z through 03Z, and at this point it is largely a
waiting game for convective initiation. Damaging winds, large hail,
and isolated tornadoes are all still in play.
Cold pool associated with the upper trof and low-level cold
advection will make for a chilly and raw Friday. Will maintain a low
overcast, with the chance for light rain especially in the northern
counties. POPs will range from a dry forecast south of the
Parkways...to a low-end chance in southern Indiana, and QPF will be
quite low. Tight pressure gradient behind the exiting low, and
efficient mixing will keep sustained winds at 15-25 mph with a few
gusts over 35 mph. Expect a very minimal recovery in temps, with
highs barely cracking 50 in the south. Lows Friday night will dip
into the upper 20s, which is actually just a couple degrees below
normal for this time of year. Expect a few flurries late in the
evening as the cold air finally arrives, but not looking for any
snow accumulation at all and will not mention a measurable POP.
.Long Term (Saturday through Thursday)...
Updated at 300 PM EST Feb 23 2012
Sat/Sun/Mon we`ll sit in a quiet weather period with temperatures
steadily increasing each day. Sfc high pressure will be in control
Sat/Sun with return flow beginning on Monday. Zonal flow aloft will
dominate Sat-Mon. While high temps will only be in the lower 40s
Sat, they should increase to the 50s for Sun/Mon. Low temps will be
in the mid 20s Sat night, but mid to upper 30s for Sun/Mon nights.
By Mon night, a strong upper level trough will drop south into the
Rockies creating lee side sfc cyclogenesis sometime early next
week. Models vary on the timing and sfc low/front evolution, but
generally it looks like the upper trough will push east into the
Midwest by Wed/Thurs with a sfc low pushing through the upper
Midwest. Ahead of this system, isentropic lift and very subtle
upper level waves passing through the region will begin Monday night
allowing for a 20% chance of rain showers over south central KY.
Lift and moisture return will continue to increase Tues combined
with weak upper level waves justifying an increase in POPs over the
entire area. Tues night or early Wed, the cold front or a warm
front and cold front (depending on which model soln you buy) will
cross the region causing showers and thunderstorms. There is still
quite a bit of discrepancy in the model sfc feature solns and so did
not make big changes to this forecast. As previously mentioned,
high temps for Tues/Wed will likely be warmer than what`s currently
in the forecast especially if we get a good warm surge ahead the
cold front. Will continue mid 50s to around 60 for highs Tues/Wed
until more certainty can be achieved.
Wed night/Thurs, precip should move east of the area with sfc high
pressure settling in again. High temps will cool back into the mid
40s to around 50.
&&
.Aviation (00Z TAF Issuance)...
Updated at 615 PM EST Feb 23 2012
East-west surface warm frontal boundary is currently located along
and just north of I-64. Pocket of enhanced theta-e advection
combined with strong moisture convergence seems to whats driving
initial batch of convection moving across east-central Kentucky.
Surface low still remains out towards the STL area with a surface
cold front extending southwestward. Frontal boundary has yet to
cross the Wabash or Mississippi Rivers. This front is forecast to
swing eastward through the region tonight bringing a chance of
additional convection to the region.
For KLEX...initial batch of convection will affect the terminal
early in the forecast period. There will likely be a break in the
precipitation after 24/01Z but some additional development to the
west may swing through later on. For now will keep VCSH in the
forecast through 24/08Z while keeping conditions VFR. Winds will
remain out of the southwest and then shift to the west by 24/14Z and
remain quite gusty during the day on Friday.
For KSDF...initial batch of convection developed just east of the
terminal. With the frontal boundary out to the west...expect
additional development to take place this evening with the best time
for convection between 24/00-04Z. Most precipitation should be out
of the terminal by 24/07Z. Southwest winds are likely this evening
and into the overnight hours before shifting to the west by 24/14Z.
Winds are likely to be quite strong on Friday with sustained 15-20kt
and gusts up 30kts being possible.
For KBWG...Plan on keeping VCTS in the TAF through 24/04Z as frontal
boundary remains to the west and will be pushing through. Feel that
precipitation will be east of the terminal by 24/06Z with VFR
conditions prevailing. Southwest winds of 8-14kts can be expected
this evening with a shift to the west occurring late tonight and
early Friday morning. West winds of 15-20kts with gusts of 25-30kts
will be possible during the day on Friday.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........MJ
Short Term.......RAS
Long Term........AMS
Aviation.........MJ
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
643 PM EST THU FEB 23 2012
.Update...
Update issued at 643 PM EST Feb 23 2012
Did a quick update to the forecast to account for the batch of
convection that fired up east of I-65 and will affect the Bluegrass
region early this evening. Elsewhere, lowered PoPs slightly for the
next few hours and then ramped them back up as the frontal boundary
to the west swings through the region.
It appears that we`re in a waiting game this evening with regards to
the severe weather threat. Initial batch of convection fired just
west of I-65 late this afternoon. However, strong moisture
convergence and theta-e advection appears to have spawn the
convective cluster that is currently moving through the Bluegrass
region.
Looking at the mesoscale analysis...it appears that several
variables are present which are limiting our convective potential at
the present time. First...the strong mid-level westerly flow has
prevent moisture transport northward from the south. While the
models indicated that mid-50s dewpoints would advect north...that
has not happened...yet. Secondly, ACARS soundings out of SDF this
afternoon reveal an elevated mixed layer which has led to increasing
values of convective inhibition...generally across the south and
western sections of the forecast area. Convection across the
Bluegrass is not rooted at the surface...but appears to be elevated
in nature. The strong westerly flow has also resulted in bulk shear
values of over 70kts. Vertical and 3-D analysis of the radar data
with the initial storms indicated that the shear was tilting the
updrafts quite a bit to the NE with increasing height.
While it appears that we may be entering a relative minimum in
convective coverage, recent observations do show moisture pooling
out ahead of the surface cold frontal boundary which is still west
of the Wabash and Mississippi Rivers. Quality moisture is still
lacking, but dewpoints are getting into the mid 50s. With the onset
of nocturnal cooling...I believe that this elevated mixed/warm layer
will likely mix out. This perhaps may be already occurring to the
west as inhibition is weakening quickly to the west and CAPE values
have increased a bit according to the latest SPC mesoanalysis.
I believe that we still have a window of opportunity for convection
this evening as the front pushes into the region. The HRRR and
other high resolution models appear to have backed off convection
slightly. However, these models have a history of being a bit too
pessimistic with convection in the past. The other thing we have
noted is that the surface winds have started to shift back to
southwest in areas to our west. This will likely result in a
lowering of storm-relative helicity and may result in a lesser
threat for updrafts to obtain or sustain rotation. Will continue to
monitor things closely over the next couple of hours and amend the
forecast as required.
.Short Term (Tonight through Friday night)...
Updated at 300 PM EST Feb 23 2012
...Severe Weather Possible Through This Evening...
As of 20Z, a 990 mb surface low was over central Missouri, and its
associated warm front extended eastward across Kentucky. Starting
to see more of a cloud band coinciding with the east-west pressure
trough and wind shift. A fairly extensive cu field centered on the
confluence of the Wabash and Ohio Rivers seems to be the most likely
point to initiate severe convection in the next few hours.
SPC continues to advertise a slight risk, with a better than 30%
chance for severe wind gusts centered on the Ohio River. Tornado
probabilities have been lowered, but there is still concern
especially north of the boundary, where helicity is enhanced due to
the SE surface winds.
Temperatures have warmed sufficiently even north of the boundary
that the instability is there. However the low-level moisture return
has been slower to arrive, so we will have only a narrow window to
initiate storms late this afternoon. Worst weather is still expected
from roughly 22Z through 03Z, and at this point it is largely a
waiting game for convective initiation. Damaging winds, large hail,
and isolated tornadoes are all still in play.
Cold pool associated with the upper trof and low-level cold
advection will make for a chilly and raw Friday. Will maintain a low
overcast, with the chance for light rain especially in the northern
counties. POPs will range from a dry forecast south of the
Parkways...to a low-end chance in southern Indiana, and QPF will be
quite low. Tight pressure gradient behind the exiting low, and
efficient mixing will keep sustained winds at 15-25 mph with a few
gusts over 35 mph. Expect a very minimal recovery in temps, with
highs barely cracking 50 in the south. Lows Friday night will dip
into the upper 20s, which is actually just a couple degrees below
normal for this time of year. Expect a few flurries late in the
evening as the cold air finally arrives, but not looking for any
snow accumulation at all and will not mention a measurable POP.
.Long Term (Saturday through Thursday)...
Updated at 300 PM EST Feb 23 2012
Sat/Sun/Mon we`ll sit in a quiet weather period with temperatures
steadily increasing each day. Sfc high pressure will be in control
Sat/Sun with return flow beginning on Monday. Zonal flow aloft will
dominate Sat-Mon. While high temps will only be in the lower 40s
Sat, they should increase to the 50s for Sun/Mon. Low temps will be
in the mid 20s Sat night, but mid to upper 30s for Sun/Mon nights.
By Mon night, a strong upper level trough will drop south into the
Rockies creating lee side sfc cyclogenesis sometime early next
week. Models vary on the timing and sfc low/front evolution, but
generally it looks like the upper trough will push east into the
Midwest by Wed/Thurs with a sfc low pushing through the upper
Midwest. Ahead of this system, isentropic lift and very subtle
upper level waves passing through the region will begin Monday night
allowing for a 20% chance of rain showers over south central KY.
Lift and moisture return will continue to increase Tues combined
with weak upper level waves justifying an increase in POPs over the
entire area. Tues night or early Wed, the cold front or a warm
front and cold front (depending on which model soln you buy) will
cross the region causing showers and thunderstorms. There is still
quite a bit of discrepancy in the model sfc feature solns and so did
not make big changes to this forecast. As previously mentioned,
high temps for Tues/Wed will likely be warmer than what`s currently
in the forecast especially if we get a good warm surge ahead the
cold front. Will continue mid 50s to around 60 for highs Tues/Wed
until more certainty can be achieved.
Wed night/Thurs, precip should move east of the area with sfc high
pressure settling in again. High temps will cool back into the mid
40s to around 50.
&&
.Aviation (00Z TAF Issuance)...
Updated at 615 PM EST Feb 23 2012
East-west surface warm frontal boundary is currently located along
and just north of I-64. Pocket of enhanced theta-e advection
combined with strong moisture convergence seems to whats driving
initial batch of convection moving across east-central Kentucky.
Surface low still remains out towards the STL area with a surface
cold front extending southwestward. Frontal boundary has yet to
cross the Wabash or Mississippi Rivers. This front is forecast to
swing eastward through the region tonight bringing a chance of
additional convection to the region.
For KLEX...initial batch of convection will affect the terminal
early in the forecast period. There will likely be a break in the
precipitation after 24/01Z but some additional development to the
west may swing through later on. For now will keep VCSH in the
forecast through 24/08Z while keeping conditions VFR. Winds will
remain out of the southwest and then shift to the west by 24/14Z and
remain quite gusty during the day on Friday.
For KSDF...initial batch of convection developed just east of the
terminal. With the frontal boundary out to the west...expect
additional development to take place this evening with the best time
for convection between 24/00-04Z. Most precipitation should be out
of the terminal by 24/07Z. Southwest winds are likely this evening
and into the overnight hours before shifting to the west by 24/14Z.
Winds are likely to be quite strong on Friday with sustained 15-20kt
and gusts up 30kts being possible.
For KBWG...Plan on keeping VCTS in the TAF through 24/04Z as frontal
boundary remains to the west and will be pushing through. Feel that
precipitation will be east of the terminal by 24/06Z with VFR
conditions prevailing. Southwest winds of 8-14kts can be expected
this evening with a shift to the west occurring late tonight and
early Friday morning. West winds of 15-20kts with gusts of 25-30kts
will be possible during the day on Friday.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........MJ
Short Term.......RAS
Long Term........AMS
Aviation.........MJ
AREA FORECAST DISCUSSION
NWS JACKSON KY
1238 AM EST WED FEB 22 2012
.UPDATE...
ISSUED AT 1238 AM EST WED FEB 22 2012
MADE SOME MINOR TWEAKS TO TEMPERATURES AND DEWPOINTS. ALSO DECREASED
SKY COVER FOR THE REST OF THE NIGHT WITH CLOUDS PUSHING OFF TO THE
NORTHEAST. SOME MORE HIGHS CLOUDS WILL SPREAD IN LATE TONIGHT...BUT
SHOULD BE MORE SCATTERED IN NATURE. I DID SLOW DOWN THE ARRIVAL OF
PRECIPITATION INTO OUR AREA TOMORROW MORNING GIVEN THE LATEST HRRR
AND RUC SHOWING NO MOISTURE IN OUR VICINITY UNTIL AT LEAST 18Z. GOING
TO HAVE TO TAKE A GOOD LOOK AT TOMORROW AFTERNOON BECAUSE INSTABILITY
IS LOOKING A BIT BETTER AND WITH TREMENDOUS SHEAR...WE COULD HAVE A
DAMAGING WIND THREAT. NEXT UPDATE WILL TRY TO CAPTURE MORE OF THE
CURRENT THINKING.
UPDATE ISSUED AT 947 PM EST TUE FEB 21 2012
UPDATED THE ZONES AND GRIDDED FORECASTS TO REFLECT CURRENT CONDITIONS
AND MODEL TRENDS. THE REST OF THE FORECAST IS ON TRACK. ANY CHANGES
WERE REALLY QUITE MINOR.
UPDATE ISSUED AT 633 PM EST TUE FEB 21 2012
UPDATED THE ZONES AND GRIDS TO DECREASE THE CLOUDS QUICKER AND TO
ADJUST THE TEMPERATURE...WINDS...AND DEWPOINTS TO REFLECT CURRENT
CONDITIONS AND MODEL TRENDS. THE REST OF THE FORECAST IS ON TRACK AND
THE NEXT UPDATE WILL BE SENT OUT BY 10 PM.
&&
.SHORT TERM...(TONIGHT THROUGH THURSDAY)
ISSUED AT 347 PM EST TUE FEB 21 2012
WARM AIR ADVECTION WILL PERSIST THROUGH THE PERIOD...WITH TEMPS
CONTINUING TO CLIMB. GREATER LOW LEVEL MOISTURE WILL FINALLY BE
ADVECTED INTO OUR AREA ON WEDNESDAY...ESPECIALLY IN SOUTHERN AND
EASTERN COUNTIES. COMBINED WITH FORECAST COOLING IN THE MID AND
UPPER LEVELS...THE RESULTING STEEP LAPSE RATES AND INSTABILITY SHOULD
RESULT IN AT LEAST SCATTERED SHOWERS. CAN NOT RULE OUT A FEW
LIGHTNING STRIKES EITHER. WITH STRONG ENVIRONMENTAL WINDS
ALOFT...THIS POSES A VERY SMALL RISK OF HIGH WINDS IF CONVECTION CAN
MIX THESE WINDS DOWN. ACTIVITY MAY PERSIST INTO WEDNESDAY NIGHT IN
THE WARM AIR ADVECTION REGIME...BUT WARMING ALOFT LATE WEDNESDAY
NIGHT AND THURSDAY WOULD NIX CONVECTION.
WILL LOOK FOR SOME RIDGE/VALLEY DIFFERENCES AGAIN EACH NIGHT.
HOWEVER...THINK THAT WINDS WILL WORK TO KEEP MANY OF THE NORMALLY
COLDER LOCATIONS FROM DECOUPLING COMPLETELY...WHICH WOULD RESTRICT
THE COLDEST TEMPERATURES TO THE DEEPEST VALLEYS IN THE EAST AND
SOUTHEAST.
.LONG TERM.../THURSDAY NIGHT THROUGH TUESDAY/
THE MODEL CONSENSUS GENERALLY HAS RIDGING CENTERED NEAR HISPANIOLA
AND RIDGING OFF THE WEST COAST OF THE US WITH TROUGHING IN BETWEEN
TO START THE PERIOD. THIS TROUGH WILL GRADUALLY SHIFT NORTH AND
NORTHEAST THROUGH SAT...WITH THE AXIS OF THIS TROUGH PASSING EAST
FRI NIGHT OR SAT. AS THE TROUGH APPROACHES...A RATHER POTENT SFC LOW
IS EXPECTED TO TRACK THROUGH THE OH VALLEY REGION ON THU NIGHT INTO
EARLY ON FRI. THIS SCENARIO WOULD ALSO SEND A COLD FRONT ACROSS THE
AREA LATE THU NIGHT OR FRI. THE DEEPER 20/00Z ECMWF AND 20/12Z ECMWF
LEAD TO A WETTER AND SOMEWHAT MORE DYNAMIC SOLUTION THAN RECENT GFS
RUNS. RIDGING WILL THEN WORK INTO THE REGION OVER THE WEEKEND...BUT
WILL NOT LINGER ALL THAT LONG AND IS PROGGED BY THE 20/00Z ECMWF AND
20/12Z ECMWF TO SHIFT EAST OF THE AREA BY LATE SUN NIGHT...WHILE
THIS OCCURS A BIT FASTER IN THE LESS AMPLIFIED 12Z GFS. OVERALL...
UNCERTAINTY INCREASES TO VERY LOW CONFIDENCE FROM LATE SUN ON...AS
THE RECENT GFS RUNS ARE NEARLY 24 HOURS FASTER BRINGING A TROUGH AND
ASSOCIATED SFC SYSTEM EAST INTO THE PLAINS AND ON INTO THE EASTERN
CONUS FROM THE ROCKIES AND WESTERN US MOUNTAINS COMPARED TO THE
ECMWF. SOME BRIEF RIDGING COULD BUILD INTO THE REGION BY THE END OF
THE PERIOD DEPENDING ON TIMING.
WITH TIMING UNCERTAINTIES A BLEND OF MODEL CONSENSUS AND THE
PREVIOUS FORECAST IS GENERALLY THE BEST APPROACH AT THIS TIME.
EXCEPT FOR TIMING OF EITHER GENERALLY AT NIGHT OR EARLY MORNING...
SOME THUNDERSTORMS...POSSIBLY STRONG...MIGHT BE A CONCERN FOR THU
NIGHT INTO EARLY ON FRI. THE RECENT SPC DAY 3 OUTLOOK BRUSHES THE
SOUTHWEST CWA WITH A SLIGHT RISK OF SEVERE THUNDERSTORMS. INSTABILITY
MAY BE RATHER LIMITED ESPECIALLY IN AREAS FURTHER TO THE NORTH...BUT
AT LEAST SOME GUSTY SHOWERS OR ISOLATED THUNDER SEEM PROBABLE WITH
OR PRECEDING THE COLD FRONT...WITH UNCERTAINTY IN THE EXACT TIMING.
OVERALL...RECENT MODEL RUNS ARE BRINGING INCREASING CONFIDENCE IN
MEASURABLE RAINFALL AT SOME POINT WITH THE FRONT. HAVE OPTED TO ADD
ISOLATED THUNDER TO THE GRIDS FOR THU NIGHT AT THIS POINT AND ADD
THUNDER CHANCES TO THE HWO. ALTHOUGH THE HIGHEST POPS WITH THIS
SYSTEM WILL BE WITH THE COLD FRONT...WEAKER SHORTWAVES PASSING BY IN
THE FLOW AS LATE AS FRI NIGHT AND EARLY SAT WILL BRING A CONTINUED
CHANCE FOR PRECIP...WITH ANY PRECIP THAT FALLS BY LATE FRI NIGHT OR
EARLY SAT IN THE SOUTHEAST TRENDING TOWARD SNOW SHOWERS OR
FLURRIES...AS IT WILL BE RATHER COLD ALOFT DESPITE SFC TEMPS NOT
GETTING MUCH BELOW FREEZING IF THAT IN THE LOWER ELEVATIONS. SAT
NIGHT INTO SUN...THERE SHOULD BE AT LEAST A BRIEF RESPITE FROM THE
PRECIP CHANCES...BUT A RATHER PROGRESSIVE PATTERN LEADS TO THE
THREAT OF PRECIP RETURNING BY LATE SUN NIGHT INTO MON AND LINGERING
THROUGH THE END OF THE PERIOD.
TEMPERATURES WILL BEGIN ON THE MILD SIDE...850 MB TEMPS ARE PROGGED
TO BE GENERALLY IN THE 8 TO 10C RANGE OR SO AT THE START OF THE
PERIOD...AND THEN FALL BEHIND THE COLD FRONT TO AROUND -8C OR COLDER
AROUND 12Z ON SAT...BUT THEN MODERATE BY LATE SAT NIGHT AND
SUN...WITH THIS TREND CONTINUING INTO THE START OF THE NEW WEEK. AT
THE SFC THIS SHOULD YIELD RATHER MILD TEMPERATURES AT THE START OF
THE PERIOD...WITH TEMPS FALLING TO NEAR OR SLIGHTLY BELOW NORMAL ON
FRI...WITH THE LARGEST DEPARTURES FROM NORMAL OVER THE WEEKEND.
SATURDAY SHOULD END UP BEING THE COLDEST DAY. TEMPS ARE THEN MORE OR
LESS EXPECTED TO BE NEAR NORMAL AT THE END OF THE PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1238 AM EST WED FEB 22 2012
MARGINAL LOW LEVEL WIND SHEAR TONIGHT. REALLY CAN`T JUSTIFY PUTTING IT
IN THE TAFS TONIGHT WITH SUCH MARGINAL CONDITIONS. HOWEVER...IF IT
WARRANTS...IT MAY BE ADDED WITH AN UPDATE A BIT LATER ON.
OTHERWISE...MAIN FORECAST CONCERN WILL BE POTENTIAL FOR CONVECTION
WEDNESDAY AFTERNOON AND EVENING AND SOME GUSTY DAMAGING WINDS WITH
THIS ACTIVITY. RIGHT NOW...TOO MUCH UNCERTAINTY TO PIN DOWN A TIMING
OF THE CONVECTION...BUT SOMETIME BETWEEN 18Z AND 00Z IS A GOOD BET.
MORE SHOWERS DEVELOP ALONG A CONVERGENCE BOUNDARY TOMORROW NIGHT
WHICH WILL GIVE ANOTHER ROUND OF SHOWERS OVERNIGHT. WINDS WILL BE
GUSTY TODAY OUT OF THE SOUTHWEST...BUT NOT QUITE AS STRONG AS
YESTERDAY. WELL THAT IS UNLESS YOU ARE NEAR A THUNDERSTORM WHICH
COULD PRODUCE A STRONG GUST OF WIND.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KAS
SHORT TERM...HAL
LONG TERM....JP
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
826 PM EST THU FEB 23 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE FROM THE MIDDLE MISSISSIPPI VALLEY TONIGHT TO
LAKE ERIE FRIDAY AFTERNOON WITH SHOWERS OVERNIGHT INTO EARLY
FRIDAY...CHANGING TO SNOW SHOWERS FRIDAY AFTERNOON. IT WILL TURN
VERY WINDY AND MUCH COLDER BEHIND A STRONG COLD FRONT FOR FRIDAY
AFTERNOON WITH BLUSTERY AND COLD CONDITIONS SATURDAY.
&&
.NEAR TERM /THROUGH FRIDAY/...
MODELS IN FAIRLY GOOD AGREEMENT WITH WARM FRONT LIFTING NORTH
ACROSS REGION TONIGHT AS SURFACE LOW MOVES EAST FROM THE MIDDLE
MISSISSIPPI VALLEY. LATEST RADAR SHOWS PRECIPITATION ALONG THE
WARM FRONT MOVING EAST/NORTHEAST...KEPT LIKELY TO CATEGORICAL POPS FOR THE
OVERNIGHT PERIOD. CHANCE OF THUNDER FROM THE ZANESVILLE AREA STILL
REMAINS OUT OF THE FORECAST...THINKING GREATEST INSTABILITY AND
FORCING WILL BE SOUTH OF OUR CWA. TEMPERATURES OVERNIGHT WILL BE
STEADY IN THE SOUTH WHILE TEMPERATURES WILL BE SLOWLY RISING
ACROSS THE NORTH.
POWERFUL COLD FRONT SWINGING UNDERNEATH SURFACE LOW TRACKING
TOWARD LAKE ERIE FRIDAY WILL BRING MUCH COLDER TEMPERATURES BY
AFTERNOON AFTER A RELATIVELY MILD START. EXACT TIMING OF FRONTAL
PASSAGE WILL DETERMINE HOW WARM MORNING READINGS ARE AS AN HOUR OR
TWO DIFFERENCE WILL PLAY HAVOC WITH FORECAST LOWS. MORNING RAIN
SHOWERS WILL TRANSITION TO SNOW SHOWERS IN THE AFTERNOON AS
TEMPERATURES FALL THROUGH THE 30S. TIGHT PRESSURE GRADIENT WITH
COLD ADVECTION AND FAIRLY HIGH INVERSION WILL ALLOW FOR VERY
GUSTY WINDS ALONG AND BEHIND THE FRONT. UPGRADED HIGH WIND WATCH
TO HIGH WIND WARNING FOR RIDGES. PUT OUT AN ADVISORY FOR THE
BALANCE OF THE AREA.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
STRONG COLD ADVECTION IN WEST TO NORTHWEST FLOW FRIDAY NIGHT INTO
SATURDAY WITH SNOW SHOWERS INTO SATURDAY EVENING. BEST
ACCUMULATION WILL BE IN THE SOUTHEAST RIDGES WITH TOTAL SNOWFALL
OF 3 TO 6 INCHES EXPECTED OVER A 24 TO 36 HOUR PERIOD WITH 2 TO 4
ACROSS THE I-80 CORRIDOR AND AN INCH OR LESS ELSEWHERE.
TEMPERATURES WELL BELOW NORMAL INTO SATURDAY NIGHT. WINDS WILL
DIMINISH BUT REMAIN QUITE GUSTY INTO SATURDAY. SURFACE RIDGE WILL
WORK EAST ACROSS REGION LATER SATURDAY NIGHT AND SUNDAY
DIMINISHING SNOW SHOWERS SATURDAY EVENING AND CLEARING SKIES
SUNDAY. TEMPERATURES SUNDAY WILL RECOVER TO NEAR NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
HIGH PRESSURE WILL MAINTAIN DRY AND ABOVE SEASONABLE CONDITIONS FOR
THE FIRST HALF OF THE LONG TERM PERIOD AS AN UPPER LEVEL SHORTWAVE
CROSSES THE NORTHERN GREAT LAKES MONDAY. BOTH THE ECMWF AND GFS HAVE
THIS WAVE AND IT`S ATTENDANT SURFACE LOW PRESSURE SYSTEM STRETCH A
FRONT JUST ACROSS THE LOWER GREAT LAKES. THIS FRONT THEN BECOMES A
MECHANISM FOR WHICH ADDITIONAL WAVES WILL RIDE ALONG...SIMILAR TO
TODAY`S LOW PRESSURE SYSTEM.
WHILE TIMING AND STRENGTH ISSUES BEGIN TO DEVELOP BETWEEN THE
MODELS...BOTH THE GFS/ECMWF DEVELOP A LOW THAT IS PROGGED TO
APPROACH THE REGION TUESDAY NIGHT AND WEDNESDAY BRINGING RAIN
WEDNESDAY AND A CHANGE TO SNOW SHOWERS FOR THURSDAY.
WITH DECENT MODEL CONSENSUS THROUGH THE PERIOD...KEPT A BLEND OF THE
GFS/ECMWF WHICH IS CLOSE TO HPC GUIDANCE NUMBERS. THIS MAINTAINS
TEMPERATURES ABOUT 5-10 DEGREES ABOVE NORMAL MONDAY THROUGH
WEDNESDAY FOLLOWED BY A RETURN TO SEASONABLE LEVELS BY LATE
THURSDAY.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
BASED TAF FORECAST ON BLEND OF HRRR AND NAM MODEL OUTPUT.
EXPECT PRE-WARM-FRONTAL MVFR RAIN BAND TO PASS NORTHEASTWARD THROUGH
THE UPPER OHIO VALLEY 02Z-10Z.
HAVE HIGH CONFIDENCE THAT WINDS WILL THEN BECOME THE MAIN AVIATION
HAZARD, AS FLIGHT CONDITIONS SHOULD VARY NO LOWER THAN MVFR
THROUGH FRIDAY EVENING.
NAM MODEL PROFILES SHOW WINDS INCREASING IN SPEED TO 40 KTS AT ABOVE
2 KFT AGL LATE TONIGHT, WHILE WINDS IN THE STABLE SURFACE LAYER
REMAIN LESS THAN 10 KTS. HENCE EXPECT LOW LEVEL WIND SHEAR TO
DEVELOP WITH THE WARM FRONTAL PASSAGE 10Z-14Z.
DURING THE COLD FRONTAL PASSAGE, 13Z-18Z, VERTICAL MIXING WILL HELP
SOUTHWEST WINDS TO GUST OVER 30 KTS. POSTFRONTAL WESTERLY WINDS
ALOFT WILL BE FASTER, HENCE SURFACE WIND GUSTS MAY PEAK AT OVER 40
KTS, 18Z-03Z.
OUTLOOK...FRIDAY NIGHT THROUGH TUESDAY...
A PROLONGED PERIOD OF RESTRICTIONS LIKELY WITH POST-SYSTEM
LAKE-ENHANCED SNOW SHOWERS FRIDAY NIGHT AND SATURDAY, PARTICULARLY
NORTH AND NEAR THE MOUNTAINS. VFR SUNDAY INTO TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...HIGH WIND WARNING FROM 10 AM TO 10 PM EST FRIDAY FOR MDZ001.
OH...WIND ADVISORY FROM 10 AM TO 7 PM EST FRIDAY FOR OHZ039>041-
048>050-057>059-068-069.
PA...WIND ADVISORY FROM 10 AM TO 10 PM EST FRIDAY FOR PAZ007>009-
013>016-020>023-029-031-073-075.
HIGH WIND WARNING FROM 10 AM TO 10 PM EST FRIDAY FOR PAZ074-
076.
WV...WIND ADVISORY FROM 10 AM TO 7 PM EST FRIDAY FOR WVZ001>004-012.
WIND ADVISORY FROM 10 AM TO 10 PM EST FRIDAY FOR WVZ021-022.
HIGH WIND WARNING FROM 10 AM TO 10 PM EST FRIDAY FOR WVZ023-
041.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
654 PM EST THU FEB 23 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE FROM MISSOURI TONIGHT TO LAKE ERIE FRIDAY
AFTERNOON WITH SHOWERS OVERNIGHT INTO EARLY FRIDAY...CHANGING TO
SNOW SHOWERS FRIDAY AFTERNOON. IT WILL TURN VERY WINDY AND MUCH
COLDER BEHIND A STRONG COLD FRONT FOR FRIDAY AFTERNOON WITH
BLUSTERY AND COLD CONDITIONS SATURDAY.
&&
.NEAR TERM /THROUGH FRIDAY/...
MODELS IN FAIRLY GOOD AGREEMENT WITH WARM FRONT LIFTING NORTH
ACROSS REGION TONIGHT AS SURFACE LOW MOVES EAST FROM MISSOURI.
CONFIDENT ENOUGH TO LOWER POPS BASED ON LATEST HI-RES MODELS AND
CURRENT RADAR TRENDS...KEPT PRECIPITATION OUT OF CWA UNTIL 03Z.
ALSO TOOK OUT THE CHANCE OF THUNDER FROM THE ZANESVILLE AREA...THINKING
GREATEST INSTABILITY AND FORCING WILL BE SOUTH OF OUR CWA.
TEMPERATURES OVERNIGHT WILL BE STEADY IN THE SOUTH WHILE
TEMPERATURES WILL BE SLOWLY RISING ACROSS THE NORTH.
POWERFUL COLD FRONT SWINGING UNDERNEATH SURFACE LOW TRACKING
TOWARD LAKE ERIE FRIDAY WILL BRING MUCH COLDER TEMPERATURES BY
AFTERNOON AFTER A RELATIVELY MILD START. EXACT TIMING OF FRONTAL
PASSAGE WILL DETERMINE HOW WARM MORNING READINGS ARE AS AN HOUR OR
TWO DIFFERENCE WILL PLAY HAVOC WITH FORECAST LOWS. MORNING RAIN
SHOWERS WILL TRANSITION TO SNOW SHOWERS IN THE AFTERNOON AS
TEMPERATURES FALL THROUGH THE 30S. TIGHT PRESSURE GRADIENT WITH
COLD ADVECTION AND FAIRLY HIGH INVERSION WILL ALLOW FOR VERY
GUSTY WINDS WITH AND BEHIND FRONT. HIGH WIND WATCH FOR RIDGES MID
MORNING INTO THE EVENING WITH ADVISORY CRITERIA WIND GUSTS
PROBABLE ELSEWHERE. LATER SHIFTS WILL NEED TO DETERMINE TIMING AND
EXTENT FOR ANY WIND ADVISORY.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
STRONG COLD ADVECTION IN WEST TO NORTHWEST FLOW FRIDAY NIGHT INTO
SATURDAY WITH SNOW SHOWERS INTO SATURDAY EVENING. BEST
ACCUMULATION WILL BE IN THE SOUTHEAST RIDGES WITH TOTAL SNOWFALL
OF 3 TO 6 INCHES EXPECTED OVER A 24 TO 36 HOUR PERIOD WITH 2 TO 4
ACROSS THE I-80 CORRIDOR AND AN INCH OR LESS ELSEWHERE.
TEMPERATURES WELL BELOW NORMAL INTO SATURDAY NIGHT. WINDS WILL
DIMINISH BUT REMAIN QUITE GUSTY INTO SATURDAY. SURFACE RIDGE WILL
WORK EAST ACROSS REGION LATER SATURDAY NIGHT AND SUNDAY
DIMINISHING SNOW SHOWERS SATURDAY EVENING AND CLEARING SKIES
SUNDAY. TEMPERATURES SUNDAY WILL RECOVER TO NEAR NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
HIGH PRESSURE WILL MAINTAIN DRY AND ABOVE SEASONABLE CONDITIONS FOR
THE FIRST HALF OF THE LONG TERM PERIOD AS AN UPPER LEVEL SHORTWAVE
CROSSES THE NORTHERN GREAT LAKES MONDAY. BOTH THE ECMWF AND GFS HAVE
THIS WAVE AND IT`S ATTENDANT SURFACE LOW PRESSURE SYSTEM STRETCH A
FRONT JUST ACROSS THE LOWER GREAT LAKES. THIS FRONT THEN BECOMES A
MECHANISM FOR WHICH ADDITIONAL WAVES WILL RIDE ALONG...SIMILAR TO
TODAY`S LOW PRESSURE SYSTEM.
WHILE TIMING AND STRENGTH ISSUES BEGIN TO DEVELOP BETWEEN THE
MODELS...BOTH THE GFS/ECMWF DEVELOP A LOW THAT IS PROGGED TO
APPROACH THE REGION TUESDAY NIGHT AND WEDNESDAY BRINGING RAIN
WEDNESDAY AND A CHANGE TO SNOW SHOWERS FOR THURSDAY.
WITH DECENT MODEL CONSENSUS THROUGH THE PERIOD...KEPT A BLEND OF THE
GFS/ECMWF WHICH IS CLOSE TO HPC GUIDANCE NUMBERS. THIS MAINTAINS
TEMPERATURES ABOUT 5-10 DEGREES ABOVE NORMAL MONDAY THROUGH
WEDNESDAY FOLLOWED BY A RETURN TO SEASONABLE LEVELS BY LATE
THURSDAY.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
BASED TAF FORECAST ON BLEND OF HRRR AND NAM MODEL OUTPUT.
EXPECT PRE-WARM-FRONTAL MVFR RAIN BAND TO PASS NORTHEASTWARD THROUGH
THE UPPER OHIO VALLEY 02Z-10Z.
HAVE HIGH CONFIDENCE THAT WINDS WILL THEN BECOME THE MAIN AVIATION
HAZARD, AS FLIGHT CONDITIONS SHOULD VARY NO LOWER THAN MVFR
THROUGH FRIDAY EVENING.
NAM MODEL PROFILES SHOW WINDS INCREASING IN SPEED TO 40 KTS AT ABOVE
2 KFT AGL LATE TONIGHT, WHILE WINDS IN THE STABLE SURFACE LAYER
REMAIN LESS THAN 10 KTS. HENCE EXPECT LOW LEVEL WIND SHEAR TO
DEVELOP WITH THE WARM FRONTAL PASSAGE 10Z-14Z.
DURING THE COLD FRONTAL PASSAGE, 13Z-18Z, VERTICAL MIXING WILL HELP
SOUTHWEST WINDS TO GUST OVER 30 KTS. POSTFRONTAL WESTERLY WINDS
ALOFT WILL BE FASTER, HENCE SURFACE WIND GUSTS MAY PEAK AT OVER 40
KTS, 18Z-03Z.
OUTLOOK...FRIDAY NIGHT THROUGH TUESDAY...
A PROLONGED PERIOD OF RESTRICTIONS LIKELY WITH POST-SYSTEM
LAKE-ENHANCED SNOW SHOWERS FRIDAY NIGHT AND SATURDAY, PARTICULARLY
NORTH AND NEAR THE MOUNTAINS. VFR SUNDAY INTO TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...HIGH WIND WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING FOR
MDZ001.
OH...NONE.
PA...HIGH WIND WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING FOR
PAZ074-076.
WV...HIGH WIND WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING FOR
WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1218 PM EST WED FEB 22 2012
.SYNOPSIS...
WEAK LOW PRESSURE, COMING EAST FROM ILLINOIS, WILL BRING SHOWERS
LATER TODAY AND TONIGHT. A STRONG LOW PRESSURE SYSTEM, COMING
EAST FROM COLORADO, WILL BRING ADDITIONAL SHOWERS THURSDAY INTO
FRIDAY, FOLLOWED BY A COOL DOWN TO SEASONABLE TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
MADE UPDATES TO THIS AFTERNOON AND EVENINGS FORECAST BASED OFF OF
THE CURRENT RADAR AND SATELLITE COVERAGE OF PRECIPITATION AND
CLOUD COVER. THE HRRR...RUC...SREF DO NOT BRING PRECIPITATION INTO
OUR COUNTIES UNTIL CLOSE TO 00Z SO HAVE PUSHED BACK TIMING OF POPS
FOR THE OVERNIGHT PERIOD JUST SLIGHTLY.
THE WEAK SURFACE LOW WILL APPROACH TONIGHT AND THE ASSOCIATED
SHORTWAVE DROPPING THROUGH THE BROAD 500MB TROUGH WILL HELP TO
PROGRESS A LINE OF SHOWERS ACROSS THE REGION OVERNIGHT. MAINTAINED
LIKELY POPS FOR PORTIONS OF THE OVERNIGHT AS THE HI-RES MODELS
MAINTAIN A DECENT LINE OF PRECIPITATION ORGANIZING AND REACHING THE
EASTERN ZONES BY 06Z.
AS WAS THE CASE YESTERDAY EVENING...SOME GUSTS COULD APPROACH
25-30MPH THIS AFTERNOON AS SUGGESTED BY THE NAM AND GFS MODEL
PROFILES.
MAINTAINED TEMPERATURES AROUND MAV/MET GUIDANCE WHICH IS ROUGHLY
10 DEGREES ABOVE NORMAL FOR TONIGHT.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
GFS/NAM SUPPORT THE FRONTAL BOUNDARY STALLING ACROSS THE AREA ON
THURSDAY WITH A FEW RIPPLES IN THE MID-LEVEL FLOW SERVING TO KEEP
CHANCE POPS IN THE FORECAST THROUGH THE DAY. POPS WILL INCREASE LATE
IN THE DAY ON THURSDAY AS A SURFACE LOW DEVELOPS IN THE OHIO VALLEY.
THURSDAY WILL BE THE WARMEST DAY OF THE WEEK, MOST NOTICEABLY FOR
LOCATIONS SOUTH OF THE BOUNDARY. TEMPS WILL WARM TO AROUND 15
DEGREES ABOVE NORMAL WITH IT NOT OUT OF THE QUESTION THAT SOME
LOCATIONS WILL REACH THE 60S.
THE SURFACE LOW WILL CROSS THE AREA THURSDAY NIGHT WITH A MORE
VIGOROUS SHORT WAVE MOVING ACROSS THE EASTERN GREAT LAKES ON FRIDAY.
A STRONG COLD FRONT WILL CROSS EARLY FRIDAY, WITH LIKELY
POPS UNTIL ITS PASSAGE. IN THE WAKE OF THE FRONT, COLD AIR ADVECTION
WILL KICK IN WITH PRECIPITATION BEGINNING TO CHANGE OVER TO SNOW
NORTH OF PITTSBURGH LATE IN THE DAY AS THICKNESSES DECREASE. 850MB
TEMPS WILL ONLY COOL TO AROUND -8C BY FRIDAY EVENING, SO LAKE EFFECT
SHOULD BE LIMITED. HIGHS ON FRIDAY AROUND 5 DEGREES ABOVE NORMAL
WILL LIKELY BE REACHED IN THE MORNING HOURS BEFORE COLDER AND
MORE SEASONABLE AIR IS ADVECTED INTO THE AREA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
PER RECENT HPC-PREFERRED ECMWF MODEL GUIDANCE, EXPECT POST SYSTEM
COOL DOWN TO PROVIDE A MIX WITH SNOW SHOWERS FRIDAY NIGHT AND
SATURDAY. ENSUING HIGH PRESSURE WILL PROVIDE A DRY BREAK SUNDAY INTO
MONDAY.
WITH THE UPPER LEVEL JETSTREAM ORIENTATION BECOMING MORE SOUTHWEST,
A LOW PRESSURE SYSTEM, DEVELOPING ACROSS THE SOUTHERN PLAINS SUNDAY,
WILL MOVE NORTHEAST TO NEW YORK STATE EARLY TUESDAY. HENCE EXPECT A
MIX OF RAIN AND SNOW SHOWERS ACROSS THE UPPER OHIO VALLEY MONDAY
NIGHT AND TUESDAY.
FORECASTED HIGH TEMPERATURES TO BE ABOUT 5 DEGREES COLDER THAN
NORMAL SATURDAY. LOWS SATURDAY NIGHT CAN BE CLOSER TO NORMAL,
DEPENDING ON EXTENT OF LINGERING CLOUDS.
TEMPERATURES SHOULD REBOUND TO NEAR NORMAL LEVEL SUNDAY AND UP TO
ABOUT 5 DEGREES WARMER THAN NORMAL MONDAY INTO TUESDAY.
&&
.AVIATION /17Z WEDNESDAY THROUGH SUNDAY/...
PER BLEND OF RECENT SURFACE, RADAR, AND SATELLITE DATA, COUPLED
WITH RECENT HRRR AND NAM MODEL OUTPUT, EXPECT VFR TODAY WITH
CLOUD CEILINGS NO LOWER THAN 5 KFT AGL, EXCEPT IN SCATTERED
SHOWERS WHERE CEILINGS MAY LOWER TO NEAR MVFR LEVELS. SURFACE
WINDS CAN GUST TO 20 KTS.
WITH LOW PRESSURE COMING EAST FROM ILLINOIS, EXPECT NUMEROUS MVFR
SHOWERS TO SPREAD WEST TO EAST ACROSS THE UPPER OHIO VALLEY AFTER
21Z.
OUTLOOK...THURSDAY THROUGH SUNDAY...
A PROLONGED PERIOD OF RESTRICTIONS POSSIBLE WITH RAIN SHOWERS
THURSDAY INTO FRIDAY, WITH PASSAGE OF STRONG LOW PRESSURE SYSTEM,
FOLLOWED BY POST-SYSTEM COLD POOL LOW CLOUDS AND SCATTERED SNOW
SHOWERS FRIDAY NIGHT INTO SATURDAY. HIGH PRESSURE SHOULD RESTORE
VFR SUNDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
853 AM EST WED FEB 22 2012
.SYNOPSIS...
WEAK LOW PRESSURE, COMING EAST FROM ILLINOIS, WILL BRING SHOWERS
LATER TODAY AND TONIGHT. A STRONG LOW PRESSURE SYSTEM, COMING
EAST FROM COLORADO, WILL BRING ADDITIONAL SHOWERS THURSDAY INTO
FRIDAY, FOLLOWED BY A COOL DOWN TO SEASONABLE TEMPERATURES.
&&
.NEAR TERM /THROUGH TONIGHT/...
PER BLEND OF RECENT SURFACE, RADAR, AND SATELLITE DATA, COUPLED
WITH RECENT HRRR AND NAM MODEL OUTPUT, HAVE TWEAKED COVERAGE OF
CLOUDS AND SHOWERS INTO THE AFTERNOON. FORECASTED AFTERNOON HIGH
TEMPERATURES CLOSE TO BLEND OF RECENT GFS AND NAM MOS. SURFACE
WINDS CAN GUST TO 25-30 MPH.
AS LOW PRESSURE, COMING EAST FROM ILLINOIS, PASSED THROUGH THE
UPPER OHIO VALLEY TONIGHT, SHOWERS WILL BECOME LIKELY.
ACCOMPANYING CLOUDS WILL HELP KEEP LOW TEMPERATURES MORE THAN 10
DEGREES WARMER THAN NORMAL.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
GFS/NAM SUPPORT THE FRONTAL BOUNDARY STALLING ACROSS THE AREA ON
THURSDAY WITH A FEW RIPPLES IN THE MID-LEVEL FLOW SERVING TO KEEP
CHANCE POPS IN THE FORECAST THROUGH THE DAY. POPS WILL INCREASE LATE
IN THE DAY ON THURSDAY AS A SURFACE LOW DEVELOPS IN THE OHIO VALLEY.
THURSDAY WILL BE THE WARMEST DAY OF THE WEEK, MOST NOTICEABLY FOR
LOCATIONS SOUTH OF THE BOUNDARY. TEMPS WILL WARM TO AROUND 15
DEGREES ABOVE NORMAL WITH IT NOT OUT OF THE QUESTION THAT SOME
LOCATIONS WILL REACH THE 60S.
THE SURFACE LOW WILL CROSS THE AREA THURSDAY NIGHT WITH A MORE
VIGOROUS SHORT WAVE MOVING ACROSS THE EASTERN GREAT LAKES ON FRIDAY.
A STRONG COLD FRONT WILL CROSS EARLY FRIDAY, WITH LIKELY
POPS UNTIL ITS PASSAGE. IN THE WAKE OF THE FRONT, COLD AIR ADVECTION
WILL KICK IN WITH PRECIPITATION BEGINNING TO CHANGE OVER TO SNOW
NORTH OF PITTSBURGH LATE IN THE DAY AS THICKNESSES DECREASE. 850MB
TEMPS WILL ONLY COOL TO AROUND -8C BY FRIDAY EVENING, SO LAKE EFFECT
SHOULD BE LIMITED. HIGHS ON FRIDAY AROUND 5 DEGREES ABOVE NORMAL
WILL LIKELY BE REACHED IN THE MORNING HOURS BEFORE COLDER AND
MORE SEASONABLE AIR IS ADVECTED INTO THE AREA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
PER RECENT HPC-PREFERRED ECMWF MODEL GUIDANCE, EXPECT POST SYSTEM
COOL DOWN TO PROVIDE A MIX WITH SNOW SHOWERS FRIDAY NIGHT AND
SATURDAY. ENSUING HIGH PRESSURE WILL PROVIDE A DRY BREAK SUNDAY INTO
MONDAY.
WITH THE UPPER LEVEL JETSTREAM ORIENTATION BECOMING MORE SOUTHWEST,
A LOW PRESSURE SYSTEM, DEVELOPING ACROSS THE SOUTHERN PLAINS SUNDAY,
WILL MOVE NORTHEAST TO NEW YORK STATE EARLY TUESDAY. HENCE EXPECT A
MIX OF RAIN AND SNOW SHOWERS ACROSS THE UPPER OHIO VALLEY MONDAY
NIGHT AND TUESDAY.
FORECASTED HIGH TEMPERATURES TO BE ABOUT 5 DEGREES COLDER THAN
NORMAL SATURDAY. LOWS SATURDAY NIGHT CAN BE CLOSER TO NORMAL,
DEPENDING ON EXTENT OF LINGERING CLOUDS.
TEMPERATURES SHOULD REBOUND TO NEAR NORMAL LEVEL SUNDAY AND UP TO
ABOUT 5 DEGREES WARMER THAN NORMAL MONDAY INTO TUESDAY.
&&
.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
PER BLEND OF RECENT SURFACE, RADAR, AND SATELLITE DATA, COUPLED
WITH RECENT HRRR AND NAM MODEL OUTPUT, EXPECT VFR TODAY WITH
CLOUD CEILINGS NO LOWER THAN 5 KFT AGL, EXCEPT IN SCATTERED
SHOWERS WHERE CEILINGS MAY LOWER TO NEAR MVFR LEVELS. SURFACE
WINDS CAN GUST TO 20 KTS.
WITH LOW PRESSURE COMING EAST FROM ILLINOIS, EXPECT NUMEROUS MVFR
SHOWERS TO SPREAD WEST TO EAST ACROSS THE UPPER OHIO VALLEY AFTER
21Z.
OUTLOOK...THURSDAY THROUGH SUNDAY...
A PROLONGED PERIOD OF RESTRICTIONS POSSIBLE WITH RAIN SHOWERS
THURSDAY INTO FRIDAY, WITH PASSAGE OF STRONG LOW PRESSURE SYSTEM,
FOLLOWED BY POST-SYSTEM COLD POOL LOW CLOUDS AND SCATTERED SNOW
SHOWERS FRIDAY NIGHT INTO SATURDAY. HIGH PRESSURE SHOULD RESTORE
VFR SUNDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
432 AM EST WED FEB 22 2012
.SYNOPSIS...
UNSETTLED WEATHER WITH PERIODS OF RAIN SHOWERS AND ABOVE NORMAL
TEMPERATURES CAN BE EXPECTED TODAY AND THURSDAY AS WEAK DISTURBANCES
MOVE ACROSS THE UPPER OHIO VALLEY. A SURFACE LOW WILL BRING THE BEST
CHANCE OF RAIN ACROSS THE AREA THURSDAY NIGHT INTO FRIDAY WITH A
STRONG COLD FRONT PUSHING ACROSS THE REGION. THIS WILL ALLOW FOR
MORE SEASONABLE WEATHER OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES THE UPPER OHIO VALLEY
IN A SOUTHWESTERLY FLOW WITH VORT ENERGY ALONG A WEAK SHORT WAVE
SHIFTING NORTHEAST OF THE AREA. AT THE SURFACE, A FRONTAL
BOUNDARY HAS SHIFTED EAST OF THE AREA, WITH SOUTHWESTERLY WINDS IN
ITS WAKE.
A FEW LINGERING SHOWERS WILL MOVE ACROSS THE I-80 CORRIDOR,
OTHERWISE A DRY START TO THE DAY CAN BE EXPECTED ACROSS THE AREA.
BY LATE MORNING, CHC POPS RETURN TO THE FORECAST AS THE NEXT AREA
OF WEAK VORT ENERGY MOVES INTO THE AREA AND 1000-300MB COLUMN
SATURATES. THE BEST CHANCE FOR RAIN SHOWERS WILL BE THIS EVENING
FOR AREAS NORTHWEST OF PITTSBURGH. NAM12 INDICATES THE BEST
FORCING WILL SET UP ALONG A CONVERGENCE ZONE THAT WILL DEVELOP
WITH A FRONTAL BOUNDARY.
A WEAK SURFACE LOW PASSING NORTH OF THE AREA WILL PUSH THE
AFOREMENTIONED FRONTAL BOUNDARY WITH LIKELY POPS SOUTHEASTWARD INTO
WESTERN PA AND NORTH-CENTRAL WV TONIGHT.
FOR TEMPS, WARM AIR ADVECTION WILL BE ONGOING THROUGHOUT THE DAY
WITH 850 TEMPS WARMING TO 0-2C ACROSS THE AREA. FORECAST TEMPS
THROUGH THIS PERIOD ARE CLOSE TO A MAV/MET BLEND, AROUND 10 DEGREES
ABOVE NORMAL.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
GFS/NAM SUPPORT THE FRONTAL BOUNDARY STALLING ACROSS THE AREA ON
THURSDAY WITH A FEW RIPPLES IN THE MID-LEVEL FLOW SERVING TO KEEP
CHANCE POPS IN THE FORECAST THROUGH THE DAY. POPS WILL INCREASE LATE
IN THE DAY ON THURSDAY AS A SURFACE LOW DEVELOPS IN THE OHIO VALLEY.
THURSDAY WILL BE THE WARMEST DAY OF THE WEEK, MOST NOTICEABLY FOR
LOCATIONS SOUTH OF THE BOUNDARY. TEMPS WILL WARM TO AROUND 15
DEGREES ABOVE NORMAL WITH IT NOT OUT OF THE QUESTION THAT SOME
LOCATIONS WILL REACH THE 60S.
THE SURFACE LOW WILL CROSS THE AREA THURSDAY NIGHT WITH A MORE
VIGOROUS SHORT WAVE MOVING ACROSS THE EASTERN GREAT LAKES ON FRIDAY.
A STRONG COLD FRONT WILL CROSS EARLY FRIDAY, WITH LIKELY
POPS UNTIL ITS PASSAGE. IN THE WAKE OF THE FRONT, COLD AIR ADVECTION
WILL KICK IN WITH PRECIPITATION BEGINNING TO CHANGE OVER TO SNOW
NORTH OF PITTSBURGH LATE IN THE DAY AS THICKNESSES DECREASE. 850MB
TEMPS WILL ONLY COOL TO AROUND -8C BY FRIDAY EVENING, SO LAKE EFFECT
SHOULD BE LIMITED. HIGHS ON FRIDAY AROUND 5 DEGREES ABOVE NORMAL
WILL LIKELY BE REACHED IN THE MORNING HOURS BEFORE COLDER AND
MORE SEASONABLE AIR IS ADVECTED INTO THE AREA.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
PER RECENT HPC-PREFERRED ECMWF MODEL GUIDANCE, EXPECT POST SYSTEM
COOL DOWN TO PROVIDE A MIX WITH SNOW SHOWERS FRIDAY NIGHT AND
SATURDAY. ENSUING HIGH PRESSURE WILL PROVIDE A DRY BREAK SUNDAY INTO
MONDAY.
WITH THE UPPER LEVEL JETSTREAM ORIENTATION BECOMING MORE SOUTHWEST,
A LOW PRESSURE SYSTEM, DEVELOPING ACROSS THE SOUTHERN PLAINS SUNDAY,
WILL MOVE NORTHEAST TO NEW YORK STATE EARLY TUESDAY. HENCE EXPECT A
MIX OF RAIN AND SNOW SHOWERS ACROSS THE UPPER OHIO VALLEY MONDAY
NIGHT AND TUESDAY.
FORECASTED HIGH TEMPERATURES TO BE ABOUT 5 DEGREES COLDER THAN
NORMAL SATURDAY. LOWS SATURDAY NIGHT CAN BE CLOSER TO NORMAL,
DEPENDING ON EXTENT OF LINGERING CLOUDS.
TEMPERATURES SHOULD REBOUND TO NEAR NORMAL LEVEL SUNDAY AND UP TO
ABOUT 5 DEGREES WARMER THAN NORMAL MONDAY INTO TUESDAY.
&&
.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
GENERAL VFR CAN BE EXPECTED THIS MORNING FOR ALL PORTS. A FEW
SCATTERED SHOWERS CAN BE EXPECTED ACROSS THE NORTH THIS MORNING. AS
LOW PRESSURE MOVES INTO THE REGION FROM THE WEST...EXPECT THAT
ANOTHER ROUND OF SHOWERS WILL DEVELOP BY LATE THIS AFTERNOON AND
MAY BRING A CHANCE OF RESTRICTIONS IN SHOWERS.
OUTLOOK...WEDNESDAY NIGHT THROUGH SUNDAY...
RESTRICTIONS POSSIBLE WITH RAIN SHOWERS WEDNESDAY NIGHT AND
THURSDAY. A STRONG COLD FRONTAL PASSAGE DAYTIME FRIDAY...CAN
RESULT IN A MORE PROLONGED PERIOD OF RESTRICTIONS FRIDAY INTO
SATURDAY NIGHT...WITH RAIN SHOWERS DAYTIME FRIDAY FOLLOWED BY COLD
POOL LOW CLOUDS AND SCATTERED SNOW SHOWERS FRIDAY NIGHT INTO
SATURDAY. HIGH PRESSURE SHOULD RESTORE VFR SUNDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
140 AM EST WED FEB 22 2012
.SYNOPSIS...
UNSETTLED WEATHER WITH PERIODS OF RAIN SHOWERS AND ABOVE NORMAL
TEMPERATURES CAN BE EXPECTED TODAY AND THURSDAY AS WEAK DISTURBANCES
MOVE ACROSS THE UPPER OHIO VALLEY. A SURFACE LOW WILL BRING THE BEST
CHANCE OF RAIN ACROSS THE AREA THURSDAY NIGHT INTO FRIDAY WITH A
STRONG COLD FRONT PUSHING ACROSS THE REGION LATE ON FRIDAY. THIS
WILL ALLOW FOR MORE SEASONABLE WEATHER OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
06Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO ACCOUNT
FOR RECENT RADAR TRENDS AND TO WARM TEMPS THROUGH DAWN.
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES THE UPPER OHIO VALLEY
IN A SOUTHWESTERLY FLOW WITH VORT ENERGY ALONG A WEAK SHORT WAVE
CROSSING THE AREA. A BROKEN LINE OF RAIN SHOWERS TRIGGERED BY THE
WAVE ALOFT IS PUSHING ACROSS WESTERN PA. AT THE SURFACE, A
FRONTAL BOUNDARY HAS SHIFTED EAST OF THE AREA, WITH SOUTHWESTERLY
WINDS IN ITS WAKE. THE SW FLOW HAS ALLOWED FOR TEMPERATURES TO
REMAIN FAIRLY STEADY OVERNIGHT.
TODAY...AFTER SHOWERS PUSH EAST THROUGH DAWN, A DRY SWATH OF AIR
ABOVE 600MB WILL SHIFT ACROSS THE AREA AND ALLOW FOR A DRY START
TO THE DAY. AFTER 18Z, CHC POPS RETURN TO THE FORECAST AS THE NEXT
AREA OF WEAK VORT ENERGY MOVES INTO THE AREA AND 1000-300MB COLUMN
SATURATES. THE BEST CHANCE FOR RAIN SHOWERS WILL INTO THIS EVENING
WILL BE NORTHWEST OF PITTSBURGH WITH THE NAM12 INDICATING THE BEST
FORCING SETTING UP ALONG A CONVERGENCE ZONE THAT WILL DEVELOP WITH
A FRONTAL BOUNDARY.
A WEAK SURFACE LOW PASSING NORTH OF THE AREA WILL PUSH THE
AFOREMENTIONED FRONTAL BOUNDARY WITH LIKELY POPS SOUTHEASTWARD INTO
WESTERN PA AND NORTH-CENTRAL WV TONIGHT.
FOR TEMPS, WARM AIR ADVECTION WILL BE ONGOING THROUGHOUT THE DAY
WITH 850 TEMPS WARMING TO 0-2C ACROSS THE AREA. FORECAST TEMPS
THROUGH THIS PERIOD ARE CLOSE TO A MAV/MET BLEND, AROUND 10 DEGREES
ABOVE NORMAL.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
PRECIPITATION PROBABILITIES WILL REMAIN IN THE HIGH CHANCE TO LIKELY
RANGE THROUGH THE SHORT TERM PERIOD. MODELS SHOW A WARM FRONTAL
BOUNDARY SETTING UP ALONG THE OHIO VALLEY WEDNESDAY NIGHT AND
THURSDAY...WHILE A SHORT WAVE MOVES ACROSS THE REGION.
A SURFACE LOW IS EXPECTED TO DEVELOP OVER THE MID MS VALLEY AS THE
MAIN UPPER TROUGH DIGS SOUTHEASTWARD INTO THE UPPER MIDWEST. THE
SURFACE LOW IS PROGGED TO STRENGTHEN AS IT TRACKS NORTHEAST ACROSS
OUR FORECAST AREA THURSDAY NIGHT AND FRIDAY.
TEMPERATURES WILL STAY ABOVE NORMAL WEDNESDAY INTO FRIDAY...WITH
HIGHS REACHING WELL INTO THE 50S AND PUSHING 60 FAR SOUTH THURSDAY
AFTERNOON.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
PER RECENT HPC-PREFERRED ECMWF MODEL GUIDANCE, EXPECT POST SYSTEM
COOL DOWN TO PROVIDE A MIX WITH SNOW SHOWERS FRIDAY NIGHT AND
SATURDAY. ENSUING HIGH PRESSURE WILL PROVIDE A DRY BREAK SUNDAY INTO
MONDAY.
WITH THE UPPER LEVEL JETSTREAM ORIENTATION BECOMING MORE SOUTHWEST,
A LOW PRESSURE SYSTEM, DEVELOPING ACROSS THE SOUTHERN PLAINS SUNDAY,
WILL MOVE NORTHEAST TO NEW YORK STATE EARLY TUESDAY. HENCE EXPECT A
MIX OF RAIN AND SNOW SHOWERS ACROSS THE UPPER OHIO VALLEY MONDAY
NIGHT AND TUESDAY.
FORECASTED HIGH TEMPERATURES TO BE ABOUT 5 DEGREES COLDER THAN
NORMAL SATURDAY. LOWS SATURDAY NIGHT CAN BE CLOSER TO NORMAL,
DEPENDING ON EXTENT OF LINGERING CLOUDS.
TEMPERATURES SHOULD REBOUND TO NEAR NORMAL LEVEL SUNDAY AND UP TO
ABOUT 5 DEGREES WARMER THAN NORMAL MONDAY INTO TUESDAY.
&&
.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
CONDITIONS WILL GENERALLY REMAIN VFR OVERNIGHT...EXCEPT FOR POSSIBLE
MVFR RESTRICTIONS IN A BAND OF SHOWERS MOVING THROUGH BY 08Z.
UPSTREAM SITES HAVE OBSERVED UP TO 35KT GUSTS WITH THIS LINE OF
SHOWERS...AND HAVE INCLUDED TEMPO GROUPS FOR WIND GUSTS. REST
OF OVERNIGHT PERIOD SHOULD REMAIN QUIET...THEN SW GUSTS TO 20 KTS
WILL DEVELOP WEDNESDAY MORNING. AS LOW PRESSURE MOVES INTO THE
REGION FROM THE WEST...EXPECT THAT ANOTHER ROUND OF SHOWERS WILL
DEVELOP BY LATE AFTERNOON.
OUTLOOK...WEDNESDAY NIGHT THROUGH SUNDAY...
RESTRICTIONS POSSIBLE WITH RAIN SHOWERS WEDNESDAY NIGHT AND
THURSDAY. A STRONG COLD FRONTAL PASSAGE DAYTIME FRIDAY...CAN
RESULT IN A MORE PROLONGED PERIOD OF RESTRICTIONS FRIDAY INTO
SATURDAY NIGHT...WITH RAIN SHOWERS DAYTIME FRIDAY FOLLOWED BY COLD
POOL LOW CLOUDS AND SCATTERED SNOW SHOWERS FRIDAY NIGHT INTO
SATURDAY. HIGH PRESSURE SHOULD RESTORE VFR SUNDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
108 AM EST WED FEB 22 2012
.SYNOPSIS...
UNSETTLED WEATHER WITH PERIODS OF RAIN SHOWERS AND ABOVE NORMAL
TEMPERATURES CAN BE EXPECTED TODAY AND THURSDAY AS WEAK DISTURBANCES
MOVE ACROSS THE UPPER OHIO VALLEY. A SURFACE LOW WILL BRING THE BEST
CHANCE OF RAIN ACROSS THE AREA THURSDAY NIGHT INTO FRIDAY WITH A
STRONG COLD FRONT PUSHING ACROSS THE REGION LATE ON FRIDAY. THIS
WILL ALLOW FOR MORE SEASONABLE WEATHER OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
06Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO ACCOUNT
FOR RECENT RADAR TRENDS AND TO WARM TEMPS THROUGH DAWN.
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES THE UPPER OHIO VALLEY
IN A SOUTHWESTERLY FLOW WITH VORT ENERGY ALONG A WEAK SHORT WAVE
CROSSING THE AREA. A BROKEN LINE OF RAIN SHOWERS TRIGGERED BY THE
WAVE ALOFT IS PUSHING ACROSS WESTERN PA. AT THE SURFACE, A
FRONTAL BOUNDARY HAS SHIFTED EAST OF THE AREA, WITH SOUTHWESTERLY
WINDS IN ITS WAKE. THE SW FLOW HAS ALLOWED FOR TEMPERATURES TO
REMAIN FAIRLY STEADY OVERNIGHT.
TODAY...AFTER SHOWERS PUSH EAST THROUGH DAWN, A DRY SWATH OF AIR
ABOVE 600MB WILL SHIFT ACROSS THE AREA AND ALLOW FOR A DRY START
TO THE DAY. AFTER 18Z, CHC POPS RETURN TO THE FORECAST AS THE NEXT
AREA OF WEAK VORT ENERGY MOVES INTO THE AREA AND 1000-300MB COLUMN
SATURATES. THE BEST CHANCE FOR RAIN SHOWERS WILL INTO THIS EVENING
WILL BE NORTHWEST OF PITTSBURGH WITH THE NAM12 INDICATING THE BEST
FORCING SETTING UP ALONG A CONVERGENCE ZONE THAT WILL DEVELOP WITH
A FRONTAL BOUNDARY.
A WEAK SURFACE LOW PASSING NORTH OF THE AREA WILL PUSH THE
AFOREMENTIONED FRONTAL BOUNDARY WITH LIKELY POPS SOUTHEASTWARD TO
ACROSS INTO WESTERN PA AND NORTH-CENTRAL WV TONIGHT.
FOR TEMPS, WARM AIR ADVECTION WILL BE ONGOING THROUGHOUT THE DAY
WITH 850 TEMPS WARMING TO 0-2C ACROSS THE AREA. FORECAST TEMPS
THROUGH THIS PERIOD ARE CLOSE TO A MAV/MET BLEND, AROUND 10 DEGREES
ABOVE NORMAL.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
PRECIPITATION PROBABILITIES WILL REMAIN IN THE HIGH CHANCE TO LIKELY
RANGE THROUGH THE SHORT TERM PERIOD. MODELS SHOW A WARM FRONTAL
BOUNDARY SETTING UP ALONG THE OHIO VALLEY WEDNESDAY NIGHT AND
THURSDAY...WHILE A SHORT WAVE MOVES ACROSS THE REGION.
A SURFACE LOW IS EXPECTED TO DEVELOP OVER THE MID MS VALLEY AS THE
MAIN UPPER TROUGH DIGS SOUTHEASTWARD INTO THE UPPER MIDWEST. THE
SURFACE LOW IS PROGGED TO STRENGTHEN AS IT TRACKS NORTHEAST ACROSS
OUR FORECAST AREA THURSDAY NIGHT AND FRIDAY.
TEMPERATURES WILL STAY ABOVE NORMAL WEDNESDAY INTO FRIDAY...WITH
HIGHS REACHING WELL INTO THE 50S AND PUSHING 60 FAR SOUTH THURSDAY
AFTERNOON.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
PER RECENT HPC-PREFERRED ECMWF MODEL GUIDANCE, EXPECT POST SYSTEM
COOL DOWN TO PROVIDE A MIX WITH SNOW SHOWERS FRIDAY NIGHT AND
SATURDAY. ENSUING HIGH PRESSURE WILL PROVIDE A DRY BREAK SUNDAY INTO
MONDAY.
WITH THE UPPER LEVEL JETSTREAM ORIENTATION BECOMING MORE SOUTHWEST,
A LOW PRESSURE SYSTEM, DEVELOPING ACROSS THE SOUTHERN PLAINS SUNDAY,
WILL MOVE NORTHEAST TO NEW YORK STATE EARLY TUESDAY. HENCE EXPECT A
MIX OF RAIN AND SNOW SHOWERS ACROSS THE UPPER OHIO VALLEY MONDAY
NIGHT AND TUESDAY.
FORECASTED HIGH TEMPERATURES TO BE ABOUT 5 DEGREES COLDER THAN
NORMAL SATURDAY. LOWS SATURDAY NIGHT CAN BE CLOSER TO NORMAL,
DEPENDING ON EXTENT OF LINGERING CLOUDS.
TEMPERATURES SHOULD REBOUND TO NEAR NORMAL LEVEL SUNDAY AND UP TO
ABOUT 5 DEGREES WARMER THAN NORMAL MONDAY INTO TUESDAY.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
CONDITIONS WILL GENERALLY REMAIN VFR OVERNIGHT...EXCEPT FOR POSSIBLE
MVFR RESTRICTIONS IN A BAND OF SHOWERS MOVING THROUGH BY 08Z.
UPSTREAM SITES HAVE OBSERVED UP TO 30 KT GUSTS WITH THIS LINE OF
SHOWERS...AND HAVE INCLUDED TEMPO GROUPS FOR THESE CONDITIONS. REST
OF OVERNIGHT PERIOD SHOULD REMAIN QUIET...THEN SW GUSTS TO 20 KTS
WILL DEVELOP WEDNESDAY MORNING. AS LOW PRESSURE MOVES INTO THE
REGION FROM THE WEST...EXPECT THAT ANOTHER ROUND OF SHOWERS WILL
DEVELOP BY LATE AFTERNOON.
OUTLOOK...WEDNESDAY NIGHT THROUGH SUNDAY...
RESTRICTIONS POSSIBLE WITH RAIN SHOWERS WEDNESDAY NIGHT AND
THURSDAY. A STRONG COLD FRONTAL PASSAGE DAYTIME FRIDAY...CAN
RESULT IN A MORE PROLONGED PERIOD OF RESTRICTIONS FRIDAY INTO
SATURDAY NIGHT...WITH RAIN SHOWERS DAYTIME FRIDAY FOLLOWED BY COLD
POOL LOW CLOUDS AND SCATTERED SNOW SHOWERS FRIDAY NIGHT INTO
SATURDAY. HIGH PRESSURE SHOULD RESTORE VFR SUNDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
945 PM EST THU FEB 23 2012
.UPDATE...
ISSUED AT 935 PM EST THU FEB 23 2012
BASICALLY MOVED THE TOTAL SNOWFALL NORTHWARD. A WINTER STORM
WARNING IS NOW IN EFFECT FOR ALL COUNTIES BUT THE NRN ROW...WHERE
A WINTER WEATHER ADVISORY IS IN EFFECT.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 945 PM EST THU FEB 23 2012
THE GFS AND NAM CONTINUE TO SHOW THE TROWAL ORIENTED ENE FROM THE
MKG/GRAND HAVEN AREA TO SAGINAW BAY. THE HRRR PCPN FIELDS ALSO
POINT TO THIS. LOOKING AT THE LATEST IR IMAGERY...THE SRN EDGE OF
THE COLDER CLOUD TOPS LINE UP WITH WHERE THE MODELS INDICATE THE
TROWAL WILL SET UP. ALL OF THIS SUGGESTS TO ME THAT THE MAX
SNOWFALL WILL BE A BIT FARTHER NORTH THAN WHERE WE EARLIER
THOUGHT. AS SUCH...WE ADDED SOME WARNING HEADLINES TO COVER THE
CWA EXCEPT FOR THE FAR NRN ROW...WHERE WE ADDED AN ADVISORY.
MAX FGEN WILL SET UP OVER THE CENTRAL CWA AND A GENERAL 5-9 INCH
SNOW CAN BE EXPECTED. HEAVIEST SNOWFALL WILL LIKELY BEGIN AFTER
MIDNIGHT AND CONTINUE INTO FRIDAY MORNING. THIS SNOW WILL BE A
WET/HEAVY SNOW AND WILL HAVE AN IMPACT ON THE MORNING COMMUTE. THE
PCPN WILL END FROM WEST TO EAST FRIDAY LATE MORNING/AFTERNOON.
AFTER THE UPPER UPPER LOW MOVES EAST OF THE AREA FRIDAY
AFTERNOON... THAT ALLOWS THE BETTER COLD ADVECTION TO BEGIN. WITH
CYCLONIC FLOW... 850 MB TMPS BELOW -10C MOVING IN WITH DEEP
MOISTURE ON NORTHWEST WINDS... LAKE EFFECT SNOW DEVELOPS AND
CONTINUES THROUGH THE NIGHT. THE BEST SNOWFALL FOR THIS WILL BE
DURING THE OVERNIGHT HOURS. ANOTHER 2 TO 4 INCHES ARE EXPECTED
WITH THAT IN THE TYPICAL NW FLOW AREAS. THIS TIME THROUGH THE AIR
TEMP WILL BE BELOW FREEZING SO THIS SNOW WILL BE MORE OF A FLUFFY
SNOW. ONCE AGAIN THERE IS GOOD LIFT IN THE DGZ BUT THE BEST LIFT
IS ACTUALLY BELOW THE DGZ SO THIS WILL NOT BE AS FLUFFY AS SOME
LAKE EFFECT EVENTS HAVE BEEN.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 415 PM EST THU FEB 23 2012
LINGERING LAKE EFFECT SNOW SHOWERS SATURDAY MORNING WILL END IN THE
AFTERNOON AS UPPER LEVEL FLOW BECOMES ANTICYCLONIC. DRY WEATHER IS
FORECAST SATURDAY NIGHT AND SUNDAY WITH UPPER RIDGING IN PLACE.
AT THIS TIME WE WILL MAINTAIN VERY LOW POPS FOR SUNDAY NIGHT INTO
MONDAY AS WEAK LOW PRESSURE MOVES ACROSS THE LAKE SUPERIOR REGION.
HOWEVER IT IS NOTED THAT OVERALL MEDIUM RANGE GUIDANCE TRENDS KEEP
LIGHT QPF TIED TO THIS SYSTEM NORTH OF OUR FCST AREA... SO FUTURE
SHIFTS MAY BE ABLE TO GO WITH A DRY FCST SUNDAY NIGHT/MONDAY.
A BETTER CHC FOR PCPN SHOULD COME FOR THE MIDDLE PORTION OF NEXT
WEEK AS A SOUTHERN PLAINS LOW TRACKS ENE INTO THE LOWER GREAT LAKES
REGION BY TUESDAY NIGHT/WEDNESDAY. LIGHT PCPN MAY ARRIVE AS EARLY AS
TUESDAY PRECEDING THAT SYSTEM... BUT THE BETTER CHC FOR PCPN SHOULD
HOLD OFF UNTIL TUESDAY NIGHT AND WEDNESDAY AS SUGGESTED BY 12Z ECMWF
GUIDANCE.
TRENDED THE MAX TEMP FCST A BIT MILDER FOR WEDNESDAY WITH POTENTIAL
FOR A RAIN/SNOW MIX. TEMPS SHOULD AVG NEAR TO SLIGHTLY ABOVE NORMAL
THROUGH THE LONG RANGE FCST PERIOD.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 600 PM EST THU FEB 23 2012
MAIN CHANGES TO THIS UPDATE WERE TO DELAY TIMING OF RAIN AND SNOW
AND TO INCREASE NORTHEAST WINDS OVERNIGHT. WE STILL EXPECT LIFR
CONDITIONS AREAWIDE RELATED TO MODERATE/HEAVY SNOW AND INCREASING
WINDS. THUNDER COULD EVEN ACCOMPANY PRECIPITATION AT THE
KAZO...KBTL...KJXN TERMINALS ALONG THE I-94 CORRIDOR. A BRIEF
PERIOD OF FREEZING RAIN IS POSSIBLE DURING THE CHANGEOVER...BUT WE
DO NOT EXPECT SIGNIFICANT ICING OVERALL. THIS LOOKS LIKE A PROLONGED
EVENT...SO KEPT IFR CONDITIONS AFTER 12Z.
&&
.MARINE...
ISSUED AT 415 PM EST THU FEB 23 2012
I HAVE ISSUED A SMALL CRAFT ADVISORY DUE TO THE INCREASING NORTH
WINDS TONIGHT THROUGH SATURDAY AFTERNOON. WINDS SHOULD INCREASE TO
15 TO 25 KNOTS OVERNIGHT AND CONTINUE INTO SATURDAY BEFORE
DIMINISHING DURING THE LATE AFTERNOON.
&&
.HYDROLOGY...
ISSUED AT 415 PM EST THU FEB 23 2012
THERE ARE NO WARNINGS OR ADVIOSRIES IN EFFECT FOR AREA RIVERS OR
STREAMS. TEMPERATURES ARE NOT EXPECTED TO GET COLD ENOUGH FOR ICE
JAMS TO BE AN ISSUE. METLING OF THE SNOW THAT FALLS SHOULD BE SLOW
ENOUGH TO NOT BE MUCH OF AN ISSUE EITHER.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING UNTIL NOON EST FRIDAY FOR MIZ043>046-
050>052-056>059-064>067-071>074.
WINTER WEATHER ADVISORY UNTIL NOON EST FRIDAY FOR MIZ037>040.
LM...SMALL CRAFT ADVISORY UNTIL 7 PM EST SATURDAY FOR LMZ844>849.
&&
$$
UPDATE...93
SHORT TERM...WDM 93
LONG TERM....LAURENS
AVIATION...TJT
MARINE...WDM
HYDROLOGY...WDM
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
733 PM EST THU FEB 23 2012
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 423 PM EST THU FEB 23 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
FROM MANITOBA AND NRN ONTARIO INTO THE SRN PLAINS. A VIGOROUS
SHORTWAVE TROUGH MOVING THROUGH SRN NEBRASKA SUPPORTED A BAND OF
MODERATE TO HEAVY SNOW OVER SE SD INTO NRN IA AND RAIN TO THE EAST.
AN UPSTREAM SHRTWV NEAR LAKE WINNIPEG WAS BRINGING MAINLY JUST LIGHT
SNOW OR FLURRIES IN SRN MANITOBA AND NW ONTARIO. AT THE SFC...A 990
MB LOW WAS LOCATED OVER SE MO WHILE A WEAKER 1002 MB LOW MOVING
THROUGH SE MANITOBA. A WEAK TROUGH EXTENDED FROM WEST TO EAST ACROSS
UPPER MI LEAVING VERY LIGHT WINDS OVER THE AREA. WITH PLENTY OF LOW
LEVEL MOISTURE IN PLACE THE WEAK NNE FLOW COMBINED WITH 850 MB TEMPS
AROUND -9C WAS ENOUGH TO SUPPORT SOME LIGHT SNOW SHOWERS INTO N
CNTRL UPPER MI.
EXPECT AREAS OF LIGHT SNOW SHOWERS OR FLURRIES TO PERSIST INTO THIS
EVENING CNTRL AND WEST WITH THE TROUGH OVER THE AREA AND WEAK FLOW
OFF OF LAKE SUPERIOR. ANY ACCUMULATIONS SHOULD ONLY AMOUNT TO A
TRACE OR A FEW TENTHS. AS THE MANITOBA SHRTWV MOVES TOWARD THE AREA
LATE TONIGHT INTO FRIDAY...MID LEVEL QVECTOR CONV ASSOCIATED WITH
THIS FEATURES WILL SUPPORT AN EXPANDING AREA OF LIGHT SNOW FROM NE
MN INTO WRN LAKE SUPERIOR AND WEST UPPER MI. SINCE THE NNW WINDS LOW
LEVEL WINDS FCST REMAIN RELATIVELY LIGHT THERE IS STILL SIGNIFICANT
UNCERTAINTY REGARDING THE LAKE ENHANCED SNOW POTENTIAL INTO WEST
UPPER MI AS THE HIGH RES MODELS SHOW DIFFERING SCENARIOS. THE BEST
CHANCE FOR SNOW OVER THE WEST IS EXPECTED DURING THE AFTERNOON AS
THE SHORTWAVE APPROACHES AND COLDER AIR MOVES IN WITH 850 MB TEMPS
DROP TO NEAR -12C. IF STRONGER LOW LEVEL CONV OR ONSHORE WINDS
DEVELOP SNOW AMOUNTS OF A COUPLE INCHES WILL BE POSSIBLE BY EVENING.
SCT -SHSN SHOULD ALSO DEVELOP OVER THE REST OF NRN UPPER MI AS NRLY
WINDS INCREASE. HOWEVER...SINCE THE DEEPER MOISTURE REMAINS TO THE
WEST...ONLY CHANCE POPS WERE INCLUDED.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 423 PM EST THU FEB 23 2012
FRI NGT...A CYC NLY FLOW WL DOMINATE THE UPR GRT LKS AS A SHRTWV
DIGGING SEWD THRU MN MAINTAINS LOWER HGTS/HIER MID LVL RH OVER THE
UPR LKS. ALTHOUGH THE FCST H85 TEMPS IN THE -12C TO -14C ARE NOT
PARTICULARLY COLD...OPTED TO MAINTAIN LIKELY POPS IN AREAS FAVORED
BY THE NNW LLVL FLOW GIVEN THE DEEP MSTR PROFILE. WENT WITH THE
HIER POPS OVER THE W CLOSER TO THE TRACK OF THE MN DISTURBANCE.
SAT...EXPECT LINGERING LES IN THE MRNG TO DIMINISH WITH THE APRCH OF
SHRTWV RDG IN PROGRESSIVE FLOW ALF AND ARRIVAL OF RISING H5 UP TO
100M BTWN 12Z-24Z/SFC HI PRES IN THE WAKE OF DEPARTING SHRTWV.
ALTHOUGH FCST LLVL NW FLOW IS FAVORABLE FOR LES IN AREAS E OF MQT...
MODELS CONSISTENTLY SHOW DRY AIR IN ONTARIO PASSING OVER ERN LK SUP
AND LIMITING SN CHCS OVER THE ERN CWA. SO CUT POPS/SN AMOUNTS SHOWN
IN PREVIOUS FCSDT.
SAT NGT...ALTHOUGH A FEW -SHSN MAY LINGER NEAR LK SUP IN THE EVNG...
BACKING FLOW TO THE SSW OVERNGT WITH PASSAGE OF RDG AXIS TO THE E
AND APRCH OF STRONG SHRTWV/SFC LO THRU THE NRN PLAINS WL PUSH ANY
REMAINING -SHSN OUT INTO THE OPEN LAKE. WITH SOME CLRG/LGT WINDS
UNDER THE RDG AXIS/PWAT ARND 0.15 INCH...TEMPS OVER THE INTERIOR MAY
FALL SHARPLY IN THE EVNG BEFORE THICKENING HI/MID CLDS RETURN LATE
WITH DVLPG ISENTROPIC ASCENT AHEAD OF THE INCOMING SHRTWV/SFC LO AND
CAUSE READINGS TO RISE LATER. TENDED TOWARD THE LO END OF GUIDANCE
FOR MIN TEMPS IN THIS AREA WITH A NON DIURNAL TEMP TREND.
SUN/SUN NGT...MODELS HAVE TRENDED A BIT FASTER WITH THE INCOMING
FCST LO PRES AS SUPPORTING SHRTWV IS FCST TO SHEAR OUT AS IT MOVES
INTO CONFLUENCE ZN BTWN MEAN RDG OVER THE SE CONUS AND PERSISTENT
WNW FLOW ALF OVER NE CAN ON SW FLANK OF CLOSED LO NEAR THE DAVIS
STRAIT. ALTHOUGH THE 12Z GFS SHOWS A MORE SHEARED OUT/WEAKER
DISTURBANCE WHILE THE CNDN MODEL DEPICTS A DEEPER SYS...VARIOUS
GUIDANCE IS IN GOOD AGREEMENT SHOWING THE LO PRES TRACK ACRS THE NRN
TIER OF THE CWA/SRN LK SUP. THIS TRACK SHOULD MINIMIZE THE THREAT OF
SGNFT SN ACCUM OVER THE FA WITH MORE PERSISTENT DEEPER FGEN UNDER
DEFORMATION ZN PASSING TO THE W AND N AND POTENTIAL DRY SLOTTING
ESPECIALL OVER THE SRN TIER CLOSER TO SUPPORTING JET CORE AXIS.
HOWEVER...COMBINATION OF FAIRLY SHARP UPR DVGC IN LEFT EXIT OF
SUPPORTING H3 JET MAX/FAIRLY VIGOROUS ISENTROPIC ASCENT SHOWN ON THE
285K SFC /ABOUT H75/ IN THE WAD PATTERN N OF ATTENDANT WARM FNT/DEEP
LYR QVECTOR CNVGC WARRANT FCST HI LIKELY POPS SPREADING IN BY AFTN.
GIVEN FCST H7 SPECIFIC HUMIDITY OF 2 G/KG...SUSPECT UP TO 2 TO 4
INCHES OF SN MAY FALL OVER THE NW CWA ON SUN...ESPECIALLY SINCE GFS
FCST SDNGS SHOW SHARP OMEGA WITHIN THE DGZ IN THAT AREA. EXPECT THE
SYNOPTIC SCALE PCPN TO DIMINISH TO LES W-E BY EARLY MON MORNING
WITH LARGE SCALE QVECTOR DVGC/DRYING FOLLOWING THE SHRTWV/SFC LO.
SINCE THERE IS A POTENTIAL FOR ADVY SN WITH THIS DISTURBANCE...OPTED
TO RETAIN MENTION IN HWO.
IN THE EXTENDED RANGE...SOME LES IS LIKELY ON MON UNDER THE MOIST
NNW FLOW LEFT IN THE WAKE OF THE DEPARTING LO THRU SE CAN AND WITH
H85 TEMPS PROGGED TO DIP AS LO AS -15C. THE ARRIVAL OF A HI PRES RDG
WL BRING QUIET WX ON TUE. ANOTHER DISTURBANCE/SFC LO MOVING IS FCST
TO MOVE THRU THE OH VALLEY ON WED. THERE HAS BEEN CONSIDERABLE MODEL
DISAGREEMENT ON THE TRACK OF THIS SHRTWV...SO RELIED ON THE
CONSENSUS OF THE MODELS FOR THE FORECAST IN THAT PERIOD. BEST SHOT
FOR ANY ACCOMPANYING SN WL BE OVER THE S. WITH HI PRES FOLLOWING
THIS SYSTEM NEXT THU...EXPECT A DRYING TREND THEN. SINCE THE
PREVAILING ZONAL FLOW ALF THRU THE EXTENDED PERIOD WL LIMIT ARCTIC
AIR INTRUSION INTO THE CONUS...EXPECT ABV NORMAL TEMPS TO PERSIST.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 730 PM EST THU FEB 23 2012
LIGHT NORTHERLY CONVERGENT WINDS WILL BRING A PERIOD OF IFR
CONDITIONS IN LAKE EFFECT SNOW AT KSAW THROUGH 02Z...ALTHOUGH SNOW
SHOULD DIMINISH TO FLURRIES THEREAFTER. A LIGHT NRLY FLOW AND
MARGINAL OVER-WATER INSTABILITY SHOULD CONTINUE MVFR CONDITIONS AT
KSAW AND KCMX THROUGH MUCH OF TONIGHT AND FRIDAY. AT KIWD...MVFR
CONDITIONS ARE EXPECTED TO GIVE WAY TO IFR CONDITIONS BY LATE FRIDAY
MORNING AS LOW-LVL CONVERGENCE INCREASES AND ENHANCEMENT OF LAKE
EFFECT SNOW IS POSSIBLE FROM UPPER DISTURBANCE MOVING ACROSS THE
AREA.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 423 PM EST THU FEB 23 2012
NRLY WINDS INCREASING INTO THE 15 TO 25 KT RANGE ARE EXPECTED LATE
FRIDAY INTO FRIDAY NIGHT AS THE GRADIENT INCREASES IN THE WAKE OF
LOW PRESSURE MOVING TOWARD THE SRN GREAT LAKES. A LOW PRESSURE
SYSTEM MOVING THROUGH THE UPPER GREAT LAKES SUNDAY INTO MONDAY WILL
ALSO BRING A PERIOD OF STRONGER WINDS. SE WINDS TO 30 KT ARE
EXPECTED IN ADVANCE OF THE LOW ON SUN. AS THE LOW MOVES TO THE EAST
OF THE AREA MONDAY NORTH TO NORTHWEST WINDS OF 20 TO 30 KT ARE ALSO
EXPECTED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KC
AVIATION...VOSS
MARINE...JLB
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
701 PM EST THU FEB 23 2012
.UPDATE...
ISSUED AT 651 PM EST THU FEB 23 2012
RAIN MOVING INTO THE REGION THIS EVENING ALREADY CHANGING TO SNOW
IN SOME LOCATIONS...INCLUDING PLAINWELL, OSHTEMO AND MANHATTAN.
THANKS TO WOODTV FOR THE TWEET OF THIS CHANGOVER OCCURING.
THIS RAIN/SNOW WILL SPREAD NORTH OVER THE NEXT FEW HOURS WITH A
RAPID CHANGE OVER TO SNOW EXPECTED. HEAVIEST ACCUMULATIONS NOW
EXPECTED TO OCCUR FROM 12AM TO 9AM...WITH RATES UP TO 2 INCHES AN
HOUR LIKELY.
MADE ONLY A FEW TWEAKS TO THE GRIDS FOR THE NEXT FEW HOURS TO
REFLECT THE PREDOMINANT RAIN ONGOING AT THIS TIME.
OTHERWISE...REMAINING FORECAST ON TRACK.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 415 PM EST THU FEB 23 2012
THE PRIMARY ISSUE IS THE WINTER STORM HEADING TOWARD THE SOUTHERN
GREAT LAKES FOR LATER TONIGHT INTO FRIDAY. THERE IS ALSO AN ISSUE
WITH LAKE EFFECT SNOW FRIDAY AFTERNOON INTO SATURDAY.
MY CURRENT THINKING IS THERE WILL BE SNOW...HEAVY AT TIMES LATE
THIS EVENING INTO MID MORNING FRIDAY. A FEW FLASHES OF LIGHTNING
ARE NOT OUT OF THE QUESTION TONIGHT EITHER. THE HEAVIEST SNOWFALL
WILL BE NEAR AND SOUTH OF INTERSTATE 96.
THERE HAS BEEN A CURIOUS SHIFT IN THE MODELS OVER THE PAST 12
HOURS WITH THE TIMING OF THE SYSTEM. MY EARLIER THINKING BROUGHT
THE HEAVY SNOW INTO THE AREA AFTER MIDNIGHT AND ENDED IT BY MID
MORNING. HOWEVER THE 18Z NAM... THE 16Z HRRR AND 12Z ECMWF SUGGEST
THE HEAVIEST SNOWFALL MAY WELL BE MOSTLY DURING THE DAY FRIDAY.
WHAT SEEMS TO BE HAPPENING IS THE WARM ADVECTION BURST OF
PRECIPITATION WILL LARGELY TRACK EAST NORTHEAST NEAR AND SOUTH OF
INTERSTATE 94 TONIGHT. THEN THE DEFORMATION BAND WITH THE UPPER
LOW IS WHAT WILL BRING THE HEAVY SNOW TO THE CENTRAL PARTS OF THE
CWA. WITH THIS LATEST THINKING THE HEAVIEST SNOW WOULD BE FROM 05
AM THROUGH 1 PM INSTEAD OF 9 PM TILL 7 AM AS EARLIER THROUGH.
THE DEEP UPPER LOW OF COURSE MEANS STRONGER FORCING...BETTER
FGEN... AND INCREASED NEG EPV. THUS OUR IDEA OF HEAVY SNOW STILL
LOOKS GOOD...MAYBE EVEN BETTER BUT JUST SLOWER. I ADDED THUNDER
DUE TO THE NEG EPV...STRONG FGEN AND THE TQ INDEX BEING OVER 15
(SUGGEST ELEVATED THUNDERSTORMS). ALSO SUPPORTING HEAVY SNOW IS
STRONG LIFT IN THE DGZ. ONLY ISSUE THERE IS THE DGZ IS ABOVE 10000
FT AGL AND IT NARROW. ON THE OTHER HAND THE DGZ DOES FALL TO BELOW
1000O FT AFTER 06Z AND GETS DEEPER. THERE IS ANOTHER AREA OF
ENHANCED LIFT IN THE DGZ TOWARD 12Z. ALL OF THIS SUPPORTS THE IDEA
OF ENHANCED SNOWFALL ACROSS THE CENTRAL CWA WITH THIS SYSTEM.
THE ECMWF 12Z AND 18Z NAM HAVE INCREASED THE QPF (WHILE DELAYING
TIMING 6 TO 12 HOURS). SO THE BOTTOM LINE IS MIXED RAIN AND SNOW
THIS EVENING OVER THE SOUTHERN 1/3 OF THE CWA. THEN SNOW SPREADING
NORTH AND EAST AFTER MIDNIGHT WITH SNOW HEAVY AT TIMES CENTRAL CWA
FRIDAY MORNING. WE ARE EXPECTING 6 TO 10 INCHES IN THE HEAVIEST
SNOW AREA.
AFTER THE UPPER UPPER LOW MOVES EAST OF THE AREA FRIDAY
AFTERNOON... THAT ALLOWS THE BETTER COLD ADVECTION TO BEGIN. WITH
CYCLONIC FLOW... 850 MB TMPS BELOW -10C MOVING IN WITH DEEP
MOISTURE ON NORTHWEST WINDS... LAKE EFFECT SNOW DEVELOPS AND
CONTINUES THROUGH THE NIGHT. THE BEST SNOWFALL FOR THIS WILL BE
DURING THE OVERNIGHT HOURS. ANOTHER 2 TO 4 INCHES ARE EXPECTED
WITH THAT IN THE TYPICAL NW FLOW AREAS. THIS TIME THROUGH THE AIR
TEMP WILL BE BELOW FREEZING SO THIS SNOW WILL BE MORE OF A FLUFFY
SNOW. ONCE AGAIN THERE IS GOOD LIFT IN THE DGZ BUT THE BEST LIFT
IS ACTUALLY BELOW THE DGZ SO THIS WILL NOT BE AS FLUFFY AS SOME
LAKE EFFECT EVENTS HAVE BEEN.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 415 PM EST THU FEB 23 2012
LINGERING LAKE EFFECT SNOW SHOWERS SATURDAY MORNING WILL END IN THE
AFTERNOON AS UPPER LEVEL FLOW BECOMES ANTICYCLONIC. DRY WEATHER IS
FORECAST SATURDAY NIGHT AND SUNDAY WITH UPPER RIDGING IN PLACE.
AT THIS TIME WE WILL MAINTAIN VERY LOW POPS FOR SUNDAY NIGHT INTO
MONDAY AS WEAK LOW PRESSURE MOVES ACROSS THE LAKE SUPERIOR REGION.
HOWEVER IT IS NOTED THAT OVERALL MEDIUM RANGE GUIDANCE TRENDS KEEP
LIGHT QPF TIED TO THIS SYSTEM NORTH OF OUR FCST AREA... SO FUTURE
SHIFTS MAY BE ABLE TO GO WITH A DRY FCST SUNDAY NIGHT/MONDAY.
A BETTER CHC FOR PCPN SHOULD COME FOR THE MIDDLE PORTION OF NEXT
WEEK AS A SOUTHERN PLAINS LOW TRACKS ENE INTO THE LOWER GREAT LAKES
REGION BY TUESDAY NIGHT/WEDNESDAY. LIGHT PCPN MAY ARRIVE AS EARLY AS
TUESDAY PRECEDING THAT SYSTEM... BUT THE BETTER CHC FOR PCPN SHOULD
HOLD OFF UNTIL TUESDAY NIGHT AND WEDNESDAY AS SUGGESTED BY 12Z ECMWF
GUIDANCE.
TRENDED THE MAX TEMP FCST A BIT MILDER FOR WEDNESDAY WITH POTENTIAL
FOR A RAIN/SNOW MIX. TEMPS SHOULD AVG NEAR TO SLIGHTLY ABOVE NORMAL
THROUGH THE LONG RANGE FCST PERIOD.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 600 PM EST THU FEB 23 2012
MAIN CHANGES TO THIS UPDATE WERE TO DELAY TIMING OF RAIN AND SNOW
AND TO INCREASE NORTHEAST WINDS OVERNIGHT. WE STILL EXPECT LIFR
CONDITIONS AREAWIDE RELATED TO MODERATE/HEAVY SNOW AND INCREASING
WINDS. THUNDER COULD EVEN ACCOMPANY PRECIPITATION AT THE
KAZO...KBTL...KJXN TERMINALS ALONG THE I-94 CORRIDOR. A BRIEF
PERIOD OF FREEZING RAIN IS POSSIBLE DURING THE CHANGEOVER...BUT WE
DO NOT EXPECT SIGNIFICANT ICING OVERALL. THIS LOOKS LIKE A PROLONGED
EVENT...SO KEPT IFR CONDITIONS AFTER 12Z.
&&
.MARINE...
ISSUED AT 415 PM EST THU FEB 23 2012
I HAVE ISSUED A SMALL CRAFT ADVISORY DUE TO THE INCREASING NORTH
WINDS TONIGHT THROUGH SATURDAY AFTERNOON. WINDS SHOULD INCREASE TO
15 TO 25 KNOTS OVERNIGHT AND CONTINUE INTO SATURDAY BEFORE
DIMINISHING DURING THE LATE AFTERNOON.
&&
.HYDROLOGY...
ISSUED AT 415 PM EST THU FEB 23 2012
THERE ARE NO WARNINGS OR ADVIOSRIES IN EFFECT FOR AREA RIVERS OR
STREAMS. TEMPERATURES ARE NOT EXPECTED TO GET COLD ENOUGH FOR ICE
JAMS TO BE AN ISSUE. METLING OF THE SNOW THAT FALLS SHOULD BE SLOW
ENOUGH TO NOT BE MUCH OF AN ISSUE EITHER.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING UNTIL NOON EST FRIDAY FOR MIZ056>059-
064>067-071>074.
WINTER WEATHER ADVISORY UNTIL NOON EST FRIDAY FOR MIZ044>046-
050>052.
LM...SMALL CRAFT ADVISORY UNTIL 7 PM EST SATURDAY FOR LMZ844>849.
&&
$$
UPDATE...JMM
SHORT TERM...WDM
LONG TERM....LAURENS
AVIATION...TJT
MARINE...WDM
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
445 PM EST WED FEB 22 2012
.UPDATE...
ISSUED AT 444 PM EST WED FEB 22 2012
WILL BE ISSUING A WINTER STORM WATCH SHORTLY FOR THE CWA FROM
THURSDAY AFTERNOON INTO FRIDAY MORNING BASED LARGELY ON LATEST
ECMWF GUIDANCE. WILL TRY TO HAVE THE WATCH OUT BY 5 PM.
&&
.SYNOPSIS...
ISSUED AT 400 PM EST WED FEB 22 2012
A WEAK SYSTEM WILL MOVE THROUGH THE AREA EARLY TONIGHT BRINGING A
PERIOD OF SNOW SHOWERS TO AREAS NEAR AND SOUTH OF INTERSTATE 96. A
HIGH PRESSURE RIDGE WILL MOVE ACROSS THE AREA DURING THE MID
MORNING HOURS OF THURSDAY BRINGING PARTIAL CLEARING TO THE AREA.
THEN A STORM DEVELOPING IN THE SOUTHERN PLAINS WILL HEAD TO THE
SOUTH CENTRAL GREAT LAKES FOR LATE THURSDAY NIGHT AND HEAD INTO
NEW ENGLAND FRIDAY. THAT WILL BRING A PERIOD OF SIGNIFICANT
SNOWFALL TO THE AREA THURSDAY NIGHT INTO FRIDAY. SOME LAKE EFFECT
SNOW IS EXPECTED INTO SATURDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 400 PM EST WED FEB 22 2012
THERE IS THE THREAT FOR A SIGNIFICANT SNOWFALL EVENT THURSDAY
NIGHT INTO FRIDAY. CURRENT THINKING IS 4 TO 7 INCHES OVER THE
CENTRAL CWA... NEAR INTERSTATE 96. MOST OF THE SNOW SHOULD FALL
DURING THE MID TO LATE EVENING HOURS OF THURSDAY NIGHT INTO THE
MID MORNING HOURS OF FRIDAY.
THERE IS ALSO THE THREAT FOR A BRIEF BURST OF SIGNIFICANT SNOW THIS
EVENING AS A SHORTWAVE OVER WISCONSIN HEADS EAST ACROSS LAKE
MICHIGAN AND INTENSIFIES THIS EVENING. BOTH THE HRRR SUGGESTS UP
TO .25 INCHES OF QPF IN 3 HOURS OVER PARTS OF NORTHERN OTTAWA AND
CENTRAL AND NORTHERN KENT COUNTIES BY BETWEEN 9 PM AND MIDNIGHT.
SINCE THE PRECIPITATION AREA ALREADY IS OVER CENTRAL WISCONSIN AND
IS HEADED EAST... IT WOULD SEEM MORE THAN REASONABLE THIS WOULD
IMPACT CENTRAL LOWER MICHIGAN THIS EVENING. THERE IS GOOD LIFT IN
THE DGZ AS THIS FEATURE MOVES THROUGH THE AREA SO THAT SHOULD HELP
THE SNOWFLAKE PRODUCTION. WITH SURFACE DEW POINTS IN THE MID 20S
THE SNOW WILL WET BULB DOWN THE AIR TEMP QUICKLY SO SNOW WILL REACH
THE GROUND.
ONCE THAT FEATURE MOVES EAST OF THE CWA LATER THIS EVENING SHORT
WAVE RIDGING FOLLOWS LATE TONIGHT INTO MIDDAY THURSDAY. THAT
SHOULD ALLOW THE SKIES TO BECOME PARTLY CLOUDY...AT LEAST FOR A
TIME.
THEN WE HAVE THE ISSUE OF OUR STORM ON THURSDAY NIGHT. THE GFS AND
NAM HAVE BEEN CONSISTENTLY FARTHER NORTH THEN THE ECMWF HAS BEEN
WITH THIS SYSTEM. HOWEVER... THE ECMWF HAS FINALLY SHOWED A
SIGNIFICANT SHIFT NORTHWARD IN THE TRACK OF THE SYSTEM THURSDAY
NIGHT. THE REGIONAL GEM IS FARTHER NORTH AND WEST THAN IS THE
HEMISPHERIC GEM... TRACKING THE LOW NEAR DETROIT LATE THURSDAY
NIGHT. THERE IS SIGNIFICANT FGEN SUPPORT OF THIS EVENT AS IT IS
EXIT REGION OF 165 KNOT 300 MB JET CORE THAT TURNS CYCLONIC AS
IT HEADS NORTHEAST TOWARD CENTRAL OHIO FRIDAY MORNING. THIS ALSO
CREATES QUIET THE TROWAL FEATURE WITH STRONG ISOTROPIC LIFT. THERE
IS 3 TO 4 G/KG OF WATER NEAR 700 MB WHILE THIS IS GOING ON SO
SNOWFALL AMOUNTS OF 3 TO 6 INCHES SHOULD BE EASY TO DO WITH THIS
SET UP.
I WOULD HAVE ISSUED A WINTER STORM WATCH FOR THIS EVENT EXPECT FOR
THE ISSUE OF MODEL UNCERTAINTY. I WILL LET THE MIDNIGHT SHIFT
CONSIDER DOING JUST THAT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 400 PM EST WED FEB 22 2012
UNSETTLED/ACTIVE WEATHER IS EXPECTED TO GENERALLY CONTINUE THROUGH
THE LONG TERM PORTION OF THE FORECAST...IF NOT THE NEXT COUPLE OF
WEEKS. MAIN ITEMS OF CONCERN ARE LINGERING SNOW ON FRI...LAKE EFFECT
FRI NIGHT/SAT...SYSTEM COMING IN LATE SUN THROUGH MON...AND LAKE
EFFECT AGAIN ON TUE.
AN ACTIVE JET STREAM IS EXPECTED TO AFFECT MOST OF THE COUNTRY
THROUGH THE NEXT WEEK. WE ARE EXPECTING TO SEE STRONG PIECES OF
ENERGY BE PUSHED ACROSS THE COUNTRY...FUELED BY A VERY STRONG JET
OVER THE NRN PACIFIC. A LOT OF THIS ENERGY IS EXPECTED TO DIVE SE
INTO THE WRN STATES...BEFORE LIFTING E/NE TOWARD THE GREAT LAKES
REGION.
WE WILL SEE THE FIRST IN THE SERIES OF PV ANOMALIES/WAVES BE MOVING
OUT OF THE AREA AFTER DEPOSITING ACCUMULATING SNOW THU NIGHT AND
INTO FRI. IN THE WAKE OF THIS PHASED UPPER FEATURE...A POOL OF
ARCTIC AIR TO OUR NW WILL BE TAPPED AND WILL PUSH INTO THE AREA.
SYNOPTIC SNOW WILL LIKELY BE ONGOING EARLY ON FRI BEFORE TAPERING
OFF DURING THE DAY. THE SNOW WILL TRANSITION TO SOME LAKE EFFECT AS
H850 TEMPS DROP DOWN TO AROUND -10C TO -12C. WE COULD SEE SOME
DECENT LAKE EFFECT ACCUMS FOR MAINLY NW FAVORED AREAS WITH MOISTURE
POTENTIALLY UP THROUGH 10K FT LATE FRI AND FRI NIGHT. INVERSION
HEIGHTS WILL GRADUALLY FALL THROUGH SAT AS THE UPPER FLOW WILL
TRANSITION TO ANTI-CYCLONIC BY SAT EVENING.
WE WILL SEE A BRIEF BREAK IN THE WEATHER THEN SAT NIGHT THROUGH A
GOOD PORTION OF SUN FOR MOST AREAS AS RIDGING BUILDS IN. NW AREAS
COULD SEE SOME LIGHT PCPN SUN AFTERNOON AS WAA/ISENTROPIC ASCENT
STRENGTHENS AHEAD OF THE NEXT SYSTEM. THE UNSETTLED WEATHER WILL
SPREAD ACROSS THE ENTIRE AREA SUN NIGHT AS THE NEXT STRONG WAVE
DIVING INTO THE SW U.S. EARLY IN THE WEEKEND WILL LIFT NE. THIS WILL
LIKELY TAP SOME WARMER AND MOIST AIR FROM THE GULF AND ADVECT IT
INTO THE AREA LATE SUN THROUGH MON MORNING. PCPN COULD START OFF AS
SNOW...BUT SHOULD CHANGE OVER TO RAIN FOR A PERIOD SUN NIGHT AND
EARLY MON. THUNDER CAN NOT EVEN BE RULED OUT WITH THE STRONG FORCING
ASSOCIATED WITH THE SYSTEM. NOT CONFIDENT ENOUGH YET TO ADD THUNDER
INTO THE FCST.
THE COLD FRONT WILL MOVE THROUGH ON MON...AND A FLOOD OF COLDER AIR
WILL MOVE IN ACROSS THE STATE. THIS WILL HELP TO START THE LAKE
EFFECT BACK UP AS H850 TEMPS DROP BACK DOWN TO AROUND -10C TO -12C.
MODELS ARE INDICATING THOUGH THAT THE LOW LEVEL FLOW WILL TEND TO BE
NE WITH THE WAY THE RIDGE BUILDS IN FROM THE NW. THIS WILL TEND TO
LIMIT THE LAKE EFFECT CHCS AND AMOUNTS. QUITE A BIT OF UNCERTAINTY
WITH REGARDS TO TIMING AND TRACK WITH ANOTHER WAVE THAT IS EXPECTED
TO LIFT OUT FROM THE WRN U.S. BY MID WEEK NEXT WEEK.
&&
.AVIATION...(FOR THE 21Z TAFS THROUGH 21Z THURSDAY AFTERNOON)
ISSUED AT 400 PM EST WED FEB 22 2012
I UPDATED THE TAFS TO ALLOW FOR THE BURST OF SNOW ASSOCIATED WITH
THE SHORTWAVE CROSSING EASTERN WISCONSIN AT 3 PM. THIS SHOULD REACH
THE MKG/GRR TAFS SITES AROUND 03Z AND BE EAST OF THERE BY 06Z. BY
THE TIME IT REACHES LAN AROUND 05Z IT SHOULD WEAKEN. I EXPECT IFR
CIGS/VSBY AS THE SNOW BAND MOVES ACROSS THE I-96 TAFS SITES.
THE I-94 TAF SITES SHOULD SEE MVFR CONDITIONS AS THIS ROLLS
THROUGH. ALL AREAS SHOULD SEE CLEARING TO VFR BY 09Z ONCE THIS
FEATURE HAS EXITED THE AREA.
&&
.MARINE...
ISSUED AT 400 PM EST WED FEB 22 2012
WINDS AND WAVES ARE STILL IN THE SMALL CRAFT ADVISORY RANGE LATE
THIS AFTERNOON. WINDS AND WAVES WILL DIMINISH TONIGHT OVERNIGHT AS
THE SURFACE RIDGE GETS CLOSER TO THE AREA. I WILL LET THE ADVISORY
EXPIRE AS SCHEDUALED.
&&
.HYDROLOGY...
ISSUED AT 400 PM EST WED FEB 22 2012
NO SIGNIFICANT HYDROLOGY ISSUES ARE EXPECTED AS THE PRECIPITATION
THAT FALLS WILL BE IN THE FROM FOR SNOW. NONE OF RIVERS ARE AT OR
ABOVE ACTION STAGE CURRENTLY.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...TJT
SYNOPSIS...TJT
SHORT TERM...WDM
LONG TERM....NJJ
AVIATION...WDM
MARINE...WDM
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
441 PM EST WED FEB 22 2012
.UPDATE...
ISSUED AT 440 PM EST WED FEB 22 2012
WILL BE ISSUING A WINTER STORM WATCH SHORTLY FOR THE CWA FROM
THURSDAY AFTERNOON AND LASTING INTO FRIDAY AFTERNOON. THE REASON
FOR THE LONG DURATION IS TO EMCOMPASS LAKE EFFECT BEHIND THE
STORM. MORE DETAILS ON REASONING TO FOLLOW. WILL TRY TO HAVE THE
WATCH OUT BY 5 PM.
&&
.SYNOPSIS...
ISSUED AT 400 PM EST WED FEB 22 2012
A WEAK SYSTEM WILL MOVE THROUGH THE AREA EARLY TONIGHT BRINGING A
PERIOD OF SNOW SHOWERS TO AREAS NEAR AND SOUTH OF INTERSTATE 96. A
HIGH PRESSURE RIDGE WILL MOVE ACROSS THE AREA DURING THE MID
MORNING HOURS OF THURSDAY BRINGING PARTIAL CLEARING TO THE AREA.
THEN A STORM DEVELOPING IN THE SOUTHERN PLAINS WILL HEAD TO THE
SOUTH CENTRAL GREAT LAKES FOR LATE THURSDAY NIGHT AND HEAD INTO
NEW ENGLAND FRIDAY. THAT WILL BRING A PERIOD OF SIGNIFICANT
SNOWFALL TO THE AREA THURSDAY NIGHT INTO FRIDAY. SOME LAKE EFFECT
SNOW IS EXPECTED INTO SATURDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 400 PM EST WED FEB 22 2012
THERE IS THE THREAT FOR A SIGNIFICANT SNOWFALL EVENT THURSDAY
NIGHT INTO FRIDAY. CURRENT THINKING IS 4 TO 7 INCHES OVER THE
CENTRAL CWA... NEAR INTERSTATE 96. MOST OF THE SNOW SHOULD FALL
DURING THE MID TO LATE EVENING HOURS OF THURSDAY NIGHT INTO THE
MID MORNING HOURS OF FRIDAY.
THERE IS ALSO THE THREAT FOR A BRIEF BURST OF SIGNIFICANT SNOW THIS
EVENING AS A SHORTWAVE OVER WISCONSIN HEADS EAST ACROSS LAKE
MICHIGAN AND INTENSIFIES THIS EVENING. BOTH THE HRRR SUGGESTS UP
TO .25 INCHES OF QPF IN 3 HOURS OVER PARTS OF NORTHERN OTTAWA AND
CENTRAL AND NORTHERN KENT COUNTIES BY BETWEEN 9 PM AND MIDNIGHT.
SINCE THE PRECIPITATION AREA ALREADY IS OVER CENTRAL WISCONSIN AND
IS HEADED EAST... IT WOULD SEEM MORE THAN REASONABLE THIS WOULD
IMPACT CENTRAL LOWER MICHIGAN THIS EVENING. THERE IS GOOD LIFT IN
THE DGZ AS THIS FEATURE MOVES THROUGH THE AREA SO THAT SHOULD HELP
THE SNOWFLAKE PRODUCTION. WITH SURFACE DEW POINTS IN THE MID 20S
THE SNOW WILL WET BULB DOWN THE AIR TEMP QUICKLY SO SNOW WILL REACH
THE GROUND.
ONCE THAT FEATURE MOVES EAST OF THE CWA LATER THIS EVENING SHORT
WAVE RIDGING FOLLOWS LATE TONIGHT INTO MIDDAY THURSDAY. THAT
SHOULD ALLOW THE SKIES TO BECOME PARTLY CLOUDY...AT LEAST FOR A
TIME.
THEN WE HAVE THE ISSUE OF OUR STORM ON THURSDAY NIGHT. THE GFS AND
NAM HAVE BEEN CONSISTENTLY FARTHER NORTH THEN THE ECMWF HAS BEEN
WITH THIS SYSTEM. HOWEVER... THE ECMWF HAS FINALLY SHOWED A
SIGNIFICANT SHIFT NORTHWARD IN THE TRACK OF THE SYSTEM THURSDAY
NIGHT. THE REGIONAL GEM IS FARTHER NORTH AND WEST THAN IS THE
HEMISPHERIC GEM... TRACKING THE LOW NEAR DETROIT LATE THURSDAY
NIGHT. THERE IS SIGNIFICANT FGEN SUPPORT OF THIS EVENT AS IT IS
EXIT REGION OF 165 KNOT 300 MB JET CORE THAT TURNS CYCLONIC AS
IT HEADS NORTHEAST TOWARD CENTRAL OHIO FRIDAY MORNING. THIS ALSO
CREATES QUIET THE TROWAL FEATURE WITH STRONG ISOTROPIC LIFT. THERE
IS 3 TO 4 G/KG OF WATER NEAR 700 MB WHILE THIS IS GOING ON SO
SNOWFALL AMOUNTS OF 3 TO 6 INCHES SHOULD BE EASY TO DO WITH THIS
SET UP.
I WOULD HAVE ISSUED A WINTER STORM WATCH FOR THIS EVENT EXPECT FOR
THE ISSUE OF MODEL UNCERTAINTY. I WILL LET THE MIDNIGHT SHIFT
CONSIDER DOING JUST THAT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 400 PM EST WED FEB 22 2012
UNSETTLED/ACTIVE WEATHER IS EXPECTED TO GENERALLY CONTINUE THROUGH
THE LONG TERM PORTION OF THE FORECAST...IF NOT THE NEXT COUPLE OF
WEEKS. MAIN ITEMS OF CONCERN ARE LINGERING SNOW ON FRI...LAKE EFFECT
FRI NIGHT/SAT...SYSTEM COMING IN LATE SUN THROUGH MON...AND LAKE
EFFECT AGAIN ON TUE.
AN ACTIVE JET STREAM IS EXPECTED TO AFFECT MOST OF THE COUNTRY
THROUGH THE NEXT WEEK. WE ARE EXPECTING TO SEE STRONG PIECES OF
ENERGY BE PUSHED ACROSS THE COUNTRY...FUELED BY A VERY STRONG JET
OVER THE NRN PACIFIC. A LOT OF THIS ENERGY IS EXPECTED TO DIVE SE
INTO THE WRN STATES...BEFORE LIFTING E/NE TOWARD THE GREAT LAKES
REGION.
WE WILL SEE THE FIRST IN THE SERIES OF PV ANOMALIES/WAVES BE MOVING
OUT OF THE AREA AFTER DEPOSITING ACCUMULATING SNOW THU NIGHT AND
INTO FRI. IN THE WAKE OF THIS PHASED UPPER FEATURE...A POOL OF
ARCTIC AIR TO OUR NW WILL BE TAPPED AND WILL PUSH INTO THE AREA.
SYNOPTIC SNOW WILL LIKELY BE ONGOING EARLY ON FRI BEFORE TAPERING
OFF DURING THE DAY. THE SNOW WILL TRANSITION TO SOME LAKE EFFECT AS
H850 TEMPS DROP DOWN TO AROUND -10C TO -12C. WE COULD SEE SOME
DECENT LAKE EFFECT ACCUMS FOR MAINLY NW FAVORED AREAS WITH MOISTURE
POTENTIALLY UP THROUGH 10K FT LATE FRI AND FRI NIGHT. INVERSION
HEIGHTS WILL GRADUALLY FALL THROUGH SAT AS THE UPPER FLOW WILL
TRANSITION TO ANTI-CYCLONIC BY SAT EVENING.
WE WILL SEE A BRIEF BREAK IN THE WEATHER THEN SAT NIGHT THROUGH A
GOOD PORTION OF SUN FOR MOST AREAS AS RIDGING BUILDS IN. NW AREAS
COULD SEE SOME LIGHT PCPN SUN AFTERNOON AS WAA/ISENTROPIC ASCENT
STRENGTHENS AHEAD OF THE NEXT SYSTEM. THE UNSETTLED WEATHER WILL
SPREAD ACROSS THE ENTIRE AREA SUN NIGHT AS THE NEXT STRONG WAVE
DIVING INTO THE SW U.S. EARLY IN THE WEEKEND WILL LIFT NE. THIS WILL
LIKELY TAP SOME WARMER AND MOIST AIR FROM THE GULF AND ADVECT IT
INTO THE AREA LATE SUN THROUGH MON MORNING. PCPN COULD START OFF AS
SNOW...BUT SHOULD CHANGE OVER TO RAIN FOR A PERIOD SUN NIGHT AND
EARLY MON. THUNDER CAN NOT EVEN BE RULED OUT WITH THE STRONG FORCING
ASSOCIATED WITH THE SYSTEM. NOT CONFIDENT ENOUGH YET TO ADD THUNDER
INTO THE FCST.
THE COLD FRONT WILL MOVE THROUGH ON MON...AND A FLOOD OF COLDER AIR
WILL MOVE IN ACROSS THE STATE. THIS WILL HELP TO START THE LAKE
EFFECT BACK UP AS H850 TEMPS DROP BACK DOWN TO AROUND -10C TO -12C.
MODELS ARE INDICATING THOUGH THAT THE LOW LEVEL FLOW WILL TEND TO BE
NE WITH THE WAY THE RIDGE BUILDS IN FROM THE NW. THIS WILL TEND TO
LIMIT THE LAKE EFFECT CHCS AND AMOUNTS. QUITE A BIT OF UNCERTAINTY
WITH REGARDS TO TIMING AND TRACK WITH ANOTHER WAVE THAT IS EXPECTED
TO LIFT OUT FROM THE WRN U.S. BY MID WEEK NEXT WEEK.
&&
.AVIATION...(FOR THE 21Z TAFS THROUGH 21Z THURSDAY AFTERNOON)
ISSUED AT 400 PM EST WED FEB 22 2012
I UPDATED THE TAFS TO ALLOW FOR THE BURST OF SNOW ASSOCIATED WITH
THE SHORTWAVE CROSSING EASTERN WISCONSIN AT 3 PM. THIS SHOULD REACH
THE MKG/GRR TAFS SITES AROUND 03Z AND BE EAST OF THERE BY 06Z. BY
THE TIME IT REACHES LAN AROUND 05Z IT SHOULD WEAKEN. I EXPECT IFR
CIGS/VSBY AS THE SNOW BAND MOVES ACROSS THE I-96 TAFS SITES.
THE I-94 TAF SITES SHOULD SEE MVFR CONDITIONS AS THIS ROLLS
THROUGH. ALL AREAS SHOULD SEE CLEARING TO VFR BY 09Z ONCE THIS
FEATURE HAS EXITED THE AREA.
&&
.MARINE...
ISSUED AT 400 PM EST WED FEB 22 2012
WINDS AND WAVES ARE STILL IN THE SMALL CRAFT ADVISORY RANGE LATE
THIS AFTERNOON. WINDS AND WAVES WILL DIMINISH TONIGHT OVERNIGHT AS
THE SURFACE RIDGE GETS CLOSER TO THE AREA. I WILL LET THE ADVISORY
EXPIRE AS SCHEDUALED.
&&
.HYDROLOGY...
ISSUED AT 400 PM EST WED FEB 22 2012
NO SIGNIFICANT HYDROLOGY ISSUES ARE EXPECTED AS THE PRECIPITATION
THAT FALLS WILL BE IN THE FROM FOR SNOW. NONE OF RIVERS ARE AT OR
ABOVE ACTION STAGE CURRENTLY.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...TJT
SYNOPSIS...TJT
SHORT TERM...WDM
LONG TERM....NJJ
AVIATION...WDM
MARINE...WDM
HYDRO...WDM
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
401 PM EST WED FEB 22 2012
.SYNOPSIS...
ISSUED AT 400 PM EST WED FEB 22 2012
A WEAK SYSTEM WILL MOVE THROUGH THE AREA EARLY TONIGHT BRINGING A
PERIOD OF SNOW SHOWERS TO AREAS NEAR AND SOUTH OF INTERSTATE 96. A
HIGH PRESSURE RIDGE WILL MOVE ACROSS THE AREA DURING THE MID
MORNING HOURS OF THURSDAY BRINGING PARTIAL CLEARING TO THE AREA.
THEN A STORM DEVELOPING IN THE SOUTHERN PLAINS WILL HEAD TO THE
SOUTH CENTRAL GREAT LAKES FOR LATE THURSDAY NIGHT AND HEAD INTO
NEW ENGLAND FRIDAY. THAT WILL BRING A PERIOD OF SIGNIFICANT
SNOWFALL TO THE AREA THURSDAY NIGHT INTO FRIDAY. SOME LAKE EFFECT
SNOW IS EXPECTED INTO SATURDAY.
&&
.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 400 PM EST WED FEB 22 2012
THERE IS THE THREAT FOR A SIGNIFICANT SNOWFALL EVENT THURSDAY
NIGHT INTO FRIDAY. CURRENT THINKING IS 4 TO 7 INCHES OVER THE
CENTRAL CWA... NEAR INTERSTATE 96. MOST OF THE SNOW SHOULD FALL
DURING THE MID TO LATE EVENING HOURS OF THURSDAY NIGHT INTO THE
MID MORNING HOURS OF FRIDAY.
THERE IS ALSO THE THREAT FOR A BRIEF BURST OF SIGNIFICANT SNOW THIS
EVENING AS A SHORTWAVE OVER WISCONSIN HEADS EAST ACROSS LAKE
MICHIGAN AND INTENSIFIES THIS EVENING. BOTH THE HRRR SUGGESTS UP
TO .25 INCHES OF QPF IN 3 HOURS OVER PARTS OF NORTHERN OTTAWA AND
CENTRAL AND NORTHERN KENT COUNTIES BY BETWEEN 9 PM AND MIDNIGHT.
SINCE THE PRECIPITATION AREA ALREADY IS OVER CENTRAL WISCONSIN AND
IS HEADED EAST... IT WOULD SEEM MORE THAN REASONABLE THIS WOULD
IMPACT CENTRAL LOWER MICHIGAN THIS EVENING. THERE IS GOOD LIFT IN
THE DGZ AS THIS FEATURE MOVES THROUGH THE AREA SO THAT SHOULD HELP
THE SNOWFLAKE PRODUCTION. WITH SURFACE DEW POINTS IN THE MID 20S
THE SNOW WILL WET BULB DOWN THE AIR TEMP QUICKLY SO SNOW WILL REACH
THE GROUND.
ONCE THAT FEATURE MOVES EAST OF THE CWA LATER THIS EVENING SHORT
WAVE RIDGING FOLLOWS LATE TONIGHT INTO MIDDAY THURSDAY. THAT
SHOULD ALLOW THE SKIES TO BECOME PARTLY CLOUDY...AT LEAST FOR A
TIME.
THEN WE HAVE THE ISSUE OF OUR STORM ON THURSDAY NIGHT. THE GFS AND
NAM HAVE BEEN CONSISTENTLY FARTHER NORTH THEN THE ECMWF HAS BEEN
WITH THIS SYSTEM. HOWEVER... THE ECMWF HAS FINALLY SHOWED A
SIGNIFICANT SHIFT NORTHWARD IN THE TRACK OF THE SYSTEM THURSDAY
NIGHT. THE REGIONAL GEM IS FARTHER NORTH AND WEST THAN IS THE
HEMISPHERIC GEM... TRACKING THE LOW NEAR DETROIT LATE THURSDAY
NIGHT. THERE IS SIGNIFICANT FGEN SUPPORT OF THIS EVENT AS IT IS
EXIT REGION OF 165 KNOT 300 MB JET CORE THAT TURNS CYCLONIC AS
IT HEADS NORTHEAST TOWARD CENTRAL OHIO FRIDAY MORNING. THIS ALSO
CREATES QUIET THE TROWAL FEATURE WITH STRONG ISOTROPIC LIFT. THERE
IS 3 TO 4 G/KG OF WATER NEAR 700 MB WHILE THIS IS GOING ON SO
SNOWFALL AMOUNTS OF 3 TO 6 INCHES SHOULD BE EASY TO DO WITH THIS
SET UP.
I WOULD HAVE ISSUED A WINTER STORM WATCH FOR THIS EVENT EXPECT FOR
THE ISSUE OF MODEL UNCERTAINTY. I WILL LET THE MIDNIGHT SHIFT
CONSIDER DOING JUST THAT.
.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 400 PM EST WED FEB 22 2012
UNSETTLED/ACTIVE WEATHER IS EXPECTED TO GENERALLY CONTINUE THROUGH
THE LONG TERM PORTION OF THE FORECAST...IF NOT THE NEXT COUPLE OF
WEEKS. MAIN ITEMS OF CONCERN ARE LINGERING SNOW ON FRI...LAKE EFFECT
FRI NIGHT/SAT...SYSTEM COMING IN LATE SUN THROUGH MON...AND LAKE
EFFECT AGAIN ON TUE.
AN ACTIVE JET STREAM IS EXPECTED TO AFFECT MOST OF THE COUNTRY
THROUGH THE NEXT WEEK. WE ARE EXPECTING TO SEE STRONG PIECES OF
ENERGY BE PUSHED ACROSS THE COUNTRY...FUELED BY A VERY STRONG JET
OVER THE NRN PACIFIC. A LOT OF THIS ENERGY IS EXPECTED TO DIVE SE
INTO THE WRN STATES...BEFORE LIFTING E/NE TOWARD THE GREAT LAKES
REGION.
WE WILL SEE THE FIRST IN THE SERIES OF PV ANOMALIES/WAVES BE MOVING
OUT OF THE AREA AFTER DEPOSITING ACCUMULATING SNOW THU NIGHT AND
INTO FRI. IN THE WAKE OF THIS PHASED UPPER FEATURE...A POOL OF
ARCTIC AIR TO OUR NW WILL BE TAPPED AND WILL PUSH INTO THE AREA.
SYNOPTIC SNOW WILL LIKELY BE ONGOING EARLY ON FRI BEFORE TAPERING
OFF DURING THE DAY. THE SNOW WILL TRANSITION TO SOME LAKE EFFECT AS
H850 TEMPS DROP DOWN TO AROUND -10C TO -12C. WE COULD SEE SOME
DECENT LAKE EFFECT ACCUMS FOR MAINLY NW FAVORED AREAS WITH MOISTURE
POTENTIALLY UP THROUGH 10K FT LATE FRI AND FRI NIGHT. INVERSION
HEIGHTS WILL GRADUALLY FALL THROUGH SAT AS THE UPPER FLOW WILL
TRANSITION TO ANTI-CYCLONIC BY SAT EVENING.
WE WILL SEE A BRIEF BREAK IN THE WEATHER THEN SAT NIGHT THROUGH A
GOOD PORTION OF SUN FOR MOST AREAS AS RIDGING BUILDS IN. NW AREAS
COULD SEE SOME LIGHT PCPN SUN AFTERNOON AS WAA/ISENTROPIC ASCENT
STRENGTHENS AHEAD OF THE NEXT SYSTEM. THE UNSETTLED WEATHER WILL
SPREAD ACROSS THE ENTIRE AREA SUN NIGHT AS THE NEXT STRONG WAVE
DIVING INTO THE SW U.S. EARLY IN THE WEEKEND WILL LIFT NE. THIS WILL
LIKELY TAP SOME WARMER AND MOIST AIR FROM THE GULF AND ADVECT IT
INTO THE AREA LATE SUN THROUGH MON MORNING. PCPN COULD START OFF AS
SNOW...BUT SHOULD CHANGE OVER TO RAIN FOR A PERIOD SUN NIGHT AND
EARLY MON. THUNDER CAN NOT EVEN BE RULED OUT WITH THE STRONG FORCING
ASSOCIATED WITH THE SYSTEM. NOT CONFIDENT ENOUGH YET TO ADD THUNDER
INTO THE FCST.
THE COLD FRONT WILL MOVE THROUGH ON MON...AND A FLOOD OF COLDER AIR
WILL MOVE IN ACROSS THE STATE. THIS WILL HELP TO START THE LAKE
EFFECT BACK UP AS H850 TEMPS DROP BACK DOWN TO AROUND -10C TO -12C.
MODELS ARE INDICATING THOUGH THAT THE LOW LEVEL FLOW WILL TEND TO BE
NE WITH THE WAY THE RIDGE BUILDS IN FROM THE NW. THIS WILL TEND TO
LIMIT THE LAKE EFFECT CHCS AND AMOUNTS. QUITE A BIT OF UNCERTAINTY
WITH REGARDS TO TIMING AND TRACK WITH ANOTHER WAVE THAT IS EXPECTED
TO LIFT OUT FROM THE WRN U.S. BY MID WEEK NEXT WEEK.
&&
.AVIATION...(FOR THE 21Z TAFS THROUGH 21Z THURSDAY AFTERNOON)
ISSUED AT 400 PM EST WED FEB 22 2012
I UPDATED THE TAFS TO ALLOW FOR THE BURST OF SNOW ASSOCIATED WITH
THE SHORTWAVE CROSSING EASTERN WISCONSIN AT 3 PM. THIS SHOULD REACH
THE MKG/GRR TAFS SITES AROUND 03Z AND BE EAST OF THERE BY 06Z. BY
THE TIME IT REACHES LAN AROUND 05Z IT SHOULD WEAKEN. I EXPECT IFR
CIGS/VSBY AS THE SNOW BAND MOVES ACROSS THE I-96 TAFS SITES.
THE I-94 TAF SITES SHOULD SEE MVFR CONDITIONS AS THIS ROLLS
THROUGH. ALL AREAS SHOULD SEE CLEARING TO VFR BY 09Z ONCE THIS
FEATURE HAS EXITED THE AREA.
&&
.MARINE...
ISSUED AT 400 PM EST WED FEB 22 2012
WINDS AND WAVES ARE STILL IN THE SMALL CRAFT ADVISORY RANGE LATE
THIS AFTERNOON. WINDS AND WAVES WILL DIMINISH TONIGHT OVERNIGHT AS
THE SURFACE RIDGE GETS CLOSER TO THE AREA. I WILL LET THE ADVISORY
EXPIRE AS SCHEDUALED.
&&
.HYDROLOGY...
ISSUED AT 400 PM EST WED FEB 22 2012
NO SIGNIFICANT HYDROLOGY ISSUES ARE EXPECTED AS THE PRECIPITATION
THAT FALLS WILL BE IN THE FROM FOR SNOW. NONE OF RIVERS ARE AT OR
ABOVE ACTION STAGE CURRENTLY.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 8 PM EST THIS EVENING FOR LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM....NJJ
AVIATION...WDM
MARINE...WDM
HYDROLOGY...WDM
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1209 AM EST WED FEB 22 2012
.UPDATE...
ISSUED AT 1011 PM EST TUE FEB 21 2012
MAIN FCST CONCERN OVERNIGHT IS SNOW ACCUMULATIONS OVER THE W.
WATER VAPOR IMAGERY SHOWS MID LEVEL LOW MOVING OVER WRN LAKE
SUPERIOR ATTM WITH ASSOCIATED MOIST...CYCLONIC FLOW SUPPORTING
-SN/-SHSN ACROSS NE MN INTO FAR NW WI AND W/NCNTRL UPPER MI. MORE
CONVECTIVE LOOKING -SHSN SPREADING ACROSS WRN UPPER MI PER KMQT
RADAR IMAGERY ARE JUST AHEAD OF RUC ANALYZED VORT MAX. PROBABLY SOME
DECENT SNOW RATES OCCURRING WITH THE 28+DBZ ECHOES...THOUGH SHORT
LIVED. FARTHER W...SNOW LOOKS LESS CONVECTIVE ON KDLH RADAR.
UPSTREAM...00Z KINL SOUNDING SHOWED DEEP MOISTURE TO 500MB.
HOWEVER...CAA AT THE LOWER LEVELS HAS BEEN MINIMAL TODAY AS 12Z AND
00Z 850MB TEMPS WERE -7C. THIS WILL PUT AIR MASS FLOWING OVER WRN
LAKE SUPERIOR AT THE MARGINAL THRESHOLD FOR LAKE ENHANCEMENT
OVERNIGHT. CONSIDERED POSSIBLE ADVY FOR ONTONAGON THRU KEWEENAW
OVERNIGHT INTO WED MORNING AS THIS WETTER SNOW (RATIO UNDER 20 TO 1)
FALLS UNDER LOWER ADVY CRITERIA (MAJORITY OF AREA AT LEAST 3 INCHES
IN 12HRS). GIVEN MARGINAL LAKE ENHANCEMENT CONDITIONS...OPTED TO
HOLD OFF ON ADVY ATTM. WOULD NOT BE SURPRISED TO SEE SOME OF THE
HIGHER TERRAIN AREAS AROUND THE PORCUPINE MTNS...BERGLAND...
ROCKLAND...TWIN LAKES AND PAINESDALE END UP AROUND 4 INCHES BY LATE
WED MORNING. HOWEVER...MAJORITY OF AREA SHOULD END UP IN THE 1-3 INCH
RANGE.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 400 PM EST TUE FEB 21 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER NRN
MN WITH A SHORTWAVE TROUGH EXTENDING INTO NW WI. 850-500 MB QVECTOR
CONV AND MID LEVEL FGEN ASSOCIATED WITH THE SHRTWV SUPPORTED A BAND
OF SNOW ACROSS CNTRL UPPER MI. SO...FAR ACCUMULATIONS HAVE BEEN
LIGHT...GENERALLY LESS THAN AN INCH. AT THE SFC...A 992 MB LOW WAS
LOCATED NEAR KINL WITH MOST OF THE SNOW AHEAD OF A TROUGH EXTENDING
TO THE SE THROUGH WRN UPPER MI INTO NE WI. ADDITIONAL SNOW OVER NE
MN WITH WRAP-AROUND MOISTURE NEAR THE MID LEVEL LOW WAS MOVING BACK
INTO NW WI.
RADAR TRENDS AND NAM/RUC FCST SUGGEST THAT THE INITIAL SNOWBAND WILL
MOVE OUT OF CNTRL UPPER MI INTO THE ERN CWA LATE THIS AFTERNOON AND
EVENING. THE SNOW AREA OVER MN IS ALSO EXPECTED TO SHIFT INTO WRN
UPPER MI THIS EVENING BRINGING POTENTIAL FOR ADDITIONAL LIGHT
ACCUMULATIONS OF AN INCH OR TWO. EVEN THOUGH THE STRONGER SYNOPTIC
FORCING IS FCST NEAR KIWD... THE COMBINATION OF CONVERGENT WRLY FLOW
AND 850 MB TEMPS DROPPING TO AROUND -8C WILL ALSO RESULT IN SOME
LAKE ENHANCED SNOW OVER NW UPPER MI WITH SNOWFALL AMOUNTS INTO THE 1
TO 3 INCH RANGE. AS THE WINDS VEER SLIGHTLY WED...THE LAKE ENHANCED
SNOW SHOULD ALSO MOVE INTO LOCATIONS NEAR LAKE SUPERIOR EAST OF
MUNISING. THE REMAINING SNOW OVER THE WEST WILL DIMINISH WED AS
HIGH PRESSURE AND DRIER AIR MOVE INTO THE AREA BEHIND THE DEPARTING
MID LEVEL LOW.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 400 PM EST TUE FEB 21 2012
THE 500MB LOW CURRENTLY OVER N MN THIS AFTERNOON WILL BE ALONG THE
ONTARIO/QUEBEC BORDER TO BEGIN THIS PERIOD. THE NEXT TROUGH SLIDING
IN FROM THE NW WILL BE BROAD...STRETCHING FROM W MANITOBA TO E LAKE
SUPERIOR/CENTRAL LAKE MI THURSDAY AFTERNOON. FCST MODELS BEGIN TO
DIVERGE EARLIER THAN NORMAL...THURSDAY AFTERNOON /DAY 2/.
THE 21/06Z NAM IS A QUICK OUTLIER...WITH A CLOSED LOW DEVELOPING
NEAR THE MACKINAC BRIDGE...BEFORE SHIFTING TO S QUEBEC FRIDAY
AFTERNOON. WHILE THE 21/06Z GFS HAS A SIMILAR TREND...IT IS APPROX 6
HOURS SLOWER. THE 21/09Z SREF TENDS TO FOLLOW A SOLUTION SIMILAR TO
THE GFS...WHILE THE 21/00Z CANADIAN IS AN AVERAGE BETWEEN THE
GFS/SREF AND THE MUCH SLOWER 21/00Z ECMWF /LOW OVER W ONTARIO WHILE
THE GFS HAS IT OVER THE S ONTARIO/QUEBEC BORDER/. THE ECMWF DOES NOT
PLACE THE LOW OVER THE S ONTARIO/QUEBEC BORDER UNTIL 12Z
SATURDAY...OR 18HRS BEHIND THE GFS. WILL PUSH THIS FORECAST CLOSER
TO A GFS SOLUTION THROUGH THE END OF THE WORK WEEK. THIS WILL RESULT
IN UPPER MI AND LAKE SUPERIOR STUCK BETWEEN THE FIRST SFC LOW
EXITING INTO QUEBEC AT 00Z THURSDAY...WITH THE STRONGER LOW
DEVELOPING OVER THE N PLAINS AND CENTRAL CANADA. A WEAK SFC TROUGH
WILL CONNECT THE TWO. THE MOST SIGNIFICANT CONTRAST THE MODELS CAN
BE SEEN OFF THE 00Z FRIDAY SFC MAP. THERE IS A CLUSTER OF MODELS
/GFS/NAM/SREF/ WITH THE LOW OVER CENTRAL TO N LOWER MI. BY CONTRAST
THE CANADIAN HAS IT ALONG THE LOWER MI/IA/OH BORDER...WITH THE ECMWF
ALONG THE CONFLUENCE OF THE OHIO AND MISSISSIPPI RIVERS. AS STATED
ABOVE...WILL PUSH THE FCST TO A MORE CENTRAL LOWER MI SOLUTION AT
00Z FRIDAY. THIS WILL KEEP THE BULK OF THE SYNOPTIC MOISTURE FALLING
JUST SOUTH OF THE CWA.
AFTER 18Z FRIDAY ALL OF THE SOLUTIONS COME INTO SOME BASIC AGREEMENT
OVER OUR CWA...WITH N TO NW WINDS AND 850MB TEMPS IN THE -8 TO -12C
RANGE. 850MB TEMPS OF -14 TO -16C SHOULD BE COMMON BY SUNDAY
AFTERNOON...BEFORE WAA ON MORE SW WINDS TAKE HOLD SATURDAY NIGHT.
STRONG SSW WINDS WILL LIKELY TAKE HOLD SUNDAY AFTERNOON INTO SUNDAY
NIGHT /DEPENDING ON THE TIMING OF THE NEXT LOW. THE ECMWF ENDS UP
BEING ROUGHLY 12 HOURS SLOWER THAN THE GFS WITH THIS NEXT SYSTEM
COMING OUT OF THE PLAINS. A STRONGER MORE NORTHERLY LOW OFF THE
ECMWF WOULD BRING 850MB TEMPS OF 2C...COMPARED TO THE WARMEST
READINGS OFF THE GFS OF -6C. AT 00Z TUESDAY THE SFC 983MB SFC LOW
OFF THE ECMWF IS OVER NE MN...WHILE AT THE SAME TIME THE
WEAKER/QUICKER GFS HAS A 1003MB LOW OVER FAR S QUEBEC. GIVEN THE
LOWER CONFIDENCE WITH THE FORECAST WILL NOT DIVE TO MUCH INTO THE
SPECIFICS...AND KEEP A CONSENSUS GOING FROM SATURDAY NIGHT ON. EVEN
WITH ALL THE DIFFERENCES...SUNDAY NIGHT LOOKED TO BE A GOOD
OPPORTUNITY TO INCLUDE LIKELY POPS OVER S CENTRAL UPPER MI.
OTHERWISE...WILL KEEP CHANCE OF LESS POPS GOING THROUGH MUCH OF THE
PERIOD WITH LOWER THAN NORMAL CONFIDENCE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1208 AM EST WED FEB 22 2012
MOISTURE/-SN/-SHSN WRAPPING AROUND MIDLEVEL LOW MOVING ACROSS WRN
LAKE SUPERIOR WILL AFFECT KIWD/KCMX/KSAW OVERNIGHT INTO THE MORNING
HRS. KCMX WILL BE IMPACTED MOST AS FAVORABLE UPSLOPE WESTERLY WIND
WILL LIKELY HOLD CONDITIONS TO IFR FOR MUCH OF THE OVERNIGHT. SOME
BRIEF PERIODS OF LIFR AND MVFR WILL ALSO OCCUR. AT KIWD...MVFR
CONDITIONS SHOULD PREVAIL WITH LESS LAKE INFLUENCE. AT KSAW...
DOWNSLOPING WIND COMPONENT SHOULD RESULT IN HIGHER MVFR CIGS...AND
-SN PROBABLY WON`T CAUSE MUCH VIS RESTRICTION. IMPROVEMENT WILL
OCCUR DURING THE DAY TODAY AS MIDLEVEL LOW DEPARTS...THOUGH MVFR
CONDITIONS WILL LIKELY LINGER AT KIWD/KCMX.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 400 PM EST TUE FEB 21 2012
AS LOW PRESSURE SLIDES EASTWARD THROUGH NRN LAKE SUPERIOR AND
INTO QUEBEC BY WED AFTERNOON...WRLY WINDS WILL INCREASE TO 20 TO 30
KT TONIGHT INTO WED. WINDS WILL DIMINISH LATE WED INTO WED NIGHT AS
HIGH PRES BUILDS INTO THE UPPER GREAT LAKES. WINDS WILL THEN REMAIN
RELATIVELY LIGHT INTO UNTIL FRI WHEN NRLY WINDS OF 15 TO 25 KT ARE
POSSIBLE AS LOW PRESSURE MOVES TO THE SOUTH OF THE REGION.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...ROLFSON
SHORT TERM...JLB
LONG TERM...KF
AVIATION...ROLFSON
MARINE...JLB
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
404 PM CST WED FEB 22 2012
.DISCUSSION...
SUMMARY...QUITE THE DAY HERE AT THE NWS OFFICE TODAY. THREE
POTENTIAL SNOW STORMS IN THE FORECAST AREA OVER THE NEXT 160 HOURS
AND PLENTY OF MODEL DISAGREEMENT TO GO ALONG WITH IT.
FIRST THINGS FIRST...SHORTWAVE PASSING THROUGH THIS AFTERNOON
YIELDING ISOLATED TO SCATTERED LIGHT SNOW SHOWERS...SHOULD BE
THROUGH EARLY THIS EVENING AND LOOKS DRY FOR SEVERAL HOURS BEFORE
THE SURFACE LOW FROM THE NORTHWEST. LOOK OF POTENTIAL WITH THIS
STORM FOR TONIGHT...BUT THE QUESTION TODAY HAS NOT BEEN IF THERE
WILL BE A 6+" SNOWBAND...BUT WHERE. IN GENERAL...THERE HAS BEEN
TWO CLUSTERS OF MODEL GUIDANCE: THE UKMET/EC IN ONE CAMP AND THE
GFS/GEM/SREF/ IN THE OTHER. THE 12Z NAM WAS AN OUTLIER TO THE
NORTH AND BROUGHT THE HEAVY SNOW ACROSS CENTRAL MN...INCLUDING THE
TWIN CITIES METRO. THE 18Z NAM JOINED THE GFS/SREF/GEM CAMP AND
CAME IN MUCH FURTHER SOUTH. DEBATED ON UPGRADING THE WATCH TO A
COMBINATION OF WARNING/ADVISORY WITH THE HEAVIEST ACCUMULATIONS IN
MARTIN AND FARIBAULT COUNTIES. IN FACT...EVEN HAD THE WARNING
DRAWN UP LATE THIS AFTERNOON...BUT THE LAST FRAME OF THE HRRR
AGREES QUITE WELL WITH THE ECMWF AND WOULD KEEP ALMOST ALL OF THE
SNOW OUT OF THE FORECAST AREA.
THERE IS ALREADY A LIGHTNING STRIKE UPSTREAM IN MONTANA THIS
AFTERNOON...WHICH IS USUALLY A PRETTY GOOD INDICATOR OF THE
STRENGTH OF THIS SYSTEM. NO SURPRISE WITH 992-993MB SURFACE LOW
DROPPING SOUTH ACROSS WESTERN IA BASED ON THE NAM/GFS...THERE IS
VERY GOOD 800-600MB FGEN TO GO ALONG WITH NEGATIVE EPV AND AT
LEAST SOME ELEVATED INSTABILITY-BEST LI APPROACHES THE FORECAST
AREA WITH 2/3 GRAM MIXING RATIOS OFF THE ISENTROPIC SURFACES. THE
FORECAST SIDES WITH THE GFS/GEM/NAM/SREF CLUSTER OF SOLUTIONS.
HOWEVER...LOW CONFIDENCE WITH NOW THE LATEST HRRR AGREEING QUITE
WELL WITH THE ECMWF. IT`S A FEAST OF FAMINE SITUATION-THERE WILL
LIKELY BE 6-10 INCHES...POSSIBLY A FOOT...IN A NARROW CORRIDOR
WHERE THE BEST FORCING SETS UP AND NOT MUCH TO THE NORTH OF IT.
DRAMATICALLY REDUCED POPS AND AMOUNT OF SNOW IN METRO...MIGHT BE
NOTHING AT. USUALLY GOOD SUBSIDENCE ON NORTH SIDE OF THE
DEFORMATION.
IN THE EXTENDED...THE SUNDAY/MONDAY SYSTEM LOOKS POTENT...JUST NOT
SOME MUCH FOR HERE WITH THE SURFACE LOW TRACKING OVERHEAD AND HIGH
POTENTIAL FOR DRY SLOT BASED ON THE ASSORTMENT OF OPERATIONAL RUNS
AND ENSEMBLE GUIDANCE. UNLESS SOMETHING CHANGES...A LOT OF SNOW
AND WIND IN THE DAKOTAS AND NORTHERN MN AND NOT MUCH HERE. GFS
SPITS OUT THE HIGHEST QPF...BUT IT MIGHT BE OVERDONE. THERE ARE
FAIRLY HIGH POPS IN THE FORECAST...BUT OVERALL...DOESN`T LOOK LIKE
ANYTHING MAJOR IN THE IMMEDIATE AREA. THERE`S ANOTHER WHOPPER OFF
THE GFS THIS TIME NEXT...BUT NOT SHOWING UP AS MUCH ON THE ECMWF
AND GFS ENSEMBLE TO SOME DEGREE. THE 12Z GFS HAD A BAND OF 12-18"
IN SOUTHERN MN...SOMETHING THAT WILL LIKELY CHANGE WITH TIME.
&&
.AVIATION.../18Z TAF ISSUANCE/
BIG ISSUE THIS TAF PERIOD IS POTENTIAL FOR A WINTER STORM LATE
TONIGHT/THURSDAY MORNING. FOR THESE TAFS...DISCARDED THE NAM /TOO
FAR NORTH/ AND BASICALLY TRENDED EVERYTHING AFTER THIS AFTERNOON
HEAVILY TOWARD THE GFS. FOR THIS AFTERNOON...WEAK UPPER WAVE
WORKING ACROSS MN WILL CONTINUE 050-100 TYPE CLOUD COVER.
EXPECTING NOTHING MORE OUT OF THESE CLOUDS THAN A BRIEF SN SHOWER
WITH MVFR CONDITIONS...BUT NOT ENOUGH TO WARRANT A TEMPO GROUP
ANYWHERE. GREATEST POTENTIAL FOR -SN TODAY WOULD BE AT STC/AXN.
FOR TONIGHT...WILL BE WATCHING WHAT IS LOOKING TO BE A BAND OF
HEAVY SNOW DEVELOPING ACROSS THE DAKOTAS THAT WILL MOVE INTO
SW/SRN MN...MAINLY SOUTH OF MPX TERMINALS. THE TERMINAL THAT LOOKS
TO BE MOST AT RISK FOR SEVERAL INCHES OF SNOW WOULD BE RWF. WHERE
SNOW DOES COME...MODELS INDICATING A SLOWER PROGRESSION WITH THIS
SYSTEM...SO DELAYED PRECIP MENTION A FEW HOURS FROM PREVIOUS TAF.
BIGGEST UNCERTAINTY IS HOW FAR NORTH DOES THE SNOW GET...GOING
WITH THE PREFERRED GFS/SREF/GEM BLEND...MSP AND EAU MAY NOT SEE
MUCH OF ANYTHING AT ALL. CIGS/VSBYS A TOUGH CALL AS WELL. IN THE
SNOW...IFR OR LOWER CONDITIONS ARE ALMOST CERTAIN...BUT NORTH OF
THE SNOW...THE GFS WOULD INDICATE IT MAY BE TOUGH TO EVEN GET
MVFR CIGS...WITH CLOUDS AT STC/MSP/RNH/EAU HANGING OUT AOA 10K FT.
KMSP...WEIGHED TAF HEAVILY TOWARD THE GFS...BUT DID NOT COMPLETELY
ABANDON THE SNOW IDEA AS THE GFS HAS. CONFIDENCE PRETTY HIGH THAT
A HEAVY BAND OF SNOW IS HEADING FOR SRN MN...BUT CONFIDENCE IS
PRETTY LOW ON JUST HOW FAR NORTH THE SNOW SHIELD MAKES. IF MSP
DOES SEE SNOW...IT WOULD LIKELY ONLY TOP OUT AROUND AN INCH GIVEN
CURRENT THINKING. CONFIDENCE IN CIG FORECAST TOMORROW LOW AS
WELL...BUT WOULD NOT BE SURPRISED IF AT LEAST MVFR CIGS SNEAK
NORTH OUT OF THE SNOW. FOR WINDS...SFC RIDGE WILL MOVE THROUGH
INTO TONIGHT...WITH WINDS MAINLY LGT AND VRB UNTIL AFTER
MIDNIGHT...WHEN THEY BECOME ESTABLISHED OUT OF THE EAST. OF COURSE
IF THE NAM SOLUTION IS CORRECT...THERE WOULD BE SIGNIFICANT WEATHER
ISSUES FOR THE MORNING RUSH TOMORROW.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER STORM WARNING FROM 3 AM TO 6 PM CST THURSDAY FOR
FARIBAULT-FREEBORN-MARTIN-WATONWAN.
WINTER WEATHER ADVISORY FROM 3 AM TO 6 PM CST THURSDAY FOR BLUE
EARTH-BROWN-REDWOOD-STEELE-WASECA.
WI...NONE.
&&
$$
CLF/MPG
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
529 PM CST Thu Feb 23 2012
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
As expected, temperatures soared well into the 60s within the warm
sector early this afternoon, even more so than anticipated with the
earlier update. 20Z surface analysis continued to show a complex
frontal structure with two surface lows extending from near Omaha to
near Moberly, with most of the CWA now located in the post-frontal
airmass. Gusty northwest winds will continue to surge east across
the remainder of the CWA through 00Z, accompanied by extensive
cloud cover and steadily falling temperatures.
Two primary concerns as we head into this evening.
1.) Wind. The RUC13 has done an outstanding job with the
placement/intensity of strong winds across Nebraska/Kansas today,
which justifies my earlier concern with respect to the ongoing wind
advisory. Increasing friction (terrain, trees, etc...) over the
eastern Plains coupled with the loss of daytime heating will both
act against a simple advection of upstream conditions into the
western CWA this evening. Already pushed back the start time of the
wind advisory until 6PM, which looks reasonable given the
juxtaposition of the strongest winds immediately south/southeast of
the digging mid-level trough axis. However, considering both minimal
impacts (after the evening commute) and the aforementioned
meteorology, am concerned that the advisory may no longer be
warranted. Still, we may see both sustained speeds and gusts locally
meet criteria (30/45), and will leave the headline active through
this evening. Still will be a windy/blustery evening regardless,
with 60s giving way to 30s by midnight.
2.) Precipitation. Satellite presentation with the mid level trough
over eastern Nebraska continues to improve this afternoon, and
additional deepening is expected as the wave digs southeast along
the Nebraska/Missouri border overnight. A compact area of vigorous
ascent and diabatic cooling immediately behind the trough, acting as
a small scale deformation band, may affect the far northern tier
counties between 9-10PM and shifting east through the overnight
hours. Given favorable dendritic snow growth profiles, it is
possible that a period of moderate to heavy snow could brush the
Iowa border counties, resulting in minor accumulations. Do expect
Iowa/Illinois to receive the brunt of this evening and for now have
painted an inch across the northern counties, but would not be
surprised if a short-fused advisory became necessary overnight.
Evening hazardous weather outlook will be amended as necessary to
reflect this impact. If concerns #1 and
#2 overlap at some point tonight, we could have an additional issue
with blowing snow/visibilities impacting travel north of highway 36.
Otherwise, gusty winds and strong cold advection will continue into
tomorrow. Previous forecast already reflected undercutting guidance
on temperatures and made no change there. Cyclonic flow will
maintain cloud cover, especially over the northeast half of the CWA
and would not be surprised to see a few sprinkles/flurries from time
to time either.
Return flow comes back in a hurry Saturday afternoon, with winds
increasing over the western CWA. Should see another 10-15 degree
gradient from northeast Missouri to eastern Kansas.
Bookbinder
Medium Range (Sunday through Thursday)...
The focus for the weather over the latter half of the forecast is on
two features; the first a shortwave due to zip east through the
Northern Plains into the Great Lakes Saturday into Sunday; the
second shortwave of note will then follow on quickly through the
Central Plains Monday night through Wednesday.
Leading shortwave, due to pass through the Plains Saturday/Sunday,
will be starved for moisture. A surface high slowly shifting east
along the Gulf Coast will effectively shut off any return moisture
from the Gulf over the weekend. Couple that observation with the
notable speed with which this shortwave jets east through the
Northern Plains, and precipitation of any form for the weekend looks
like a non-issue. Have kept the forecast dry, and boosted afternoon
highs on the expectation of breezy southwest winds. This should put
temperatures for the last day of the weekend into the 50s to low
60s.
After the passage of the weekend leading shortwave, a second wave is
due to pass through the Central Plains during the beginning of the
work week. Sunday`s shortwave, while dry, will have the ultimate
effect of shoving the baroclinic zone a little father south as weak
high pressure oozes into the Northern Plains, pushing afternoon
highs back down towards normal. This results in the second wave
kicking out across the plains form the Four Corners region, zipping
through the Lower Missouri River Valley. At this point the surface
high along the Gulf Coast will have advected east under the
influence of the progressive flow across the nation, leaving the
Gulf open to allow moisture return which the second shortwave will
be able to tap.
This second system has the potential to be significant weather
maker. While models are in decent enough broad agreement on the
general trend of the shortwave to warrant including likely POPs for
part of Tuesday and Tuesday night, preference on the specifics of
shortwave timing are hedged towards the faster ECMWF and GEM
solutions. GFS is the slowest in ejecting the wave, which seems a
bit off given the progressive flow. Anyhow, have limited snow POPs
to the Iowa border region where the coolest air will be, but
otherwise have a mix of rain and rain/snow across the various
forecast periods from Monday night through Wednesday. Did add in
isolated thunder for areas along and south of I-70 owing to some
limited instability present during the afternoon Tuesday.
Cutter
&&
.AVIATION...
For the 00Z TAFS, low VFR cigs will continue to lower to MVFR in the
next few hours as lower clouds have moved into northwestern MO and
will continue to advect to the southeast. Lower MVFR cigs are
expected for relatively brief period of time this evening as the low
and surface inverted trough move north of the terminals through
northern MO. There may be some light wrap around snow to impact STJ
but have kept the Kansas City terminals dry for now as there appears
to be some dry air working in on the backside of the system across
eastern NE currently. Even if snow were to work towards MCI and MKC
the impacts would be negligible given how warm it is currently and
show brief it might actually snow there.
Beyond this evening and tonight, cigs should lift and scatter around
sunrise tomorrow and remain that way for several hours. But strong
cold advection aloft and cyclonic curvature should result in clouds
moving back into the terminals for much of the afternoon. Right now
it looks as though clouds may move east as the coldest temperatures
get shifted into the Great Lakes area.
CDB
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...WIND ADVISORY until Midnight CST tonight FOR MOZ001>004-011>013-
020>022-028>030-037-038-043>045-053-054.
KS...WIND ADVISORY until Midnight CST tonight FOR KSZ025-057-060-
102>105.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS BUFFALO NY
756 PM EST THU FEB 23 2012
.SYNOPSIS...
LOW PRESSURE WILL LIFT ACROSS THE OHIO VALLEY AND EASTERN GREAT
LAKES TONIGHT...INTENSIFYING AS IT TRACKS ACROSS NORTHERN NEW
ENGLAND FRIDAY NIGHT. THIS WILL BRING SNOW TO THE REGION TONIGHT
THEN A CHANGE OF SNOW TO RAIN DURING FRIDAY MORNING. AS THE LOW
EXITS INTO THE CANADIAN MARITIMES...IT WILL BRING COLDER AIR
DEVELOPING LAKE EFFECT SNOW SHOWERS FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH FRIDAY/...
AS OF 740PM...REGIONAL RADAR SHOWING A BAND OF RAIN SPREAD FROM
NORTHERN INDIANA EASTWARD ACROSS OHIO TO FAR WESTERN PA. HIGH LEVEL
CIRRUS CLOUDS HAVE SPREAD NORTH INTO THE FORECAST AREA AHEAD OF THE
STORM SYSTEM CENTERED OVER SOUTHERN ILLINOIS. MADE SOME MINOR
ADJUSTMENTS TO CLOUD COVER AND TEMPS. SKIES ACROSS WESTERN NY
THROUGH THE SOUTHERN TIER ARE OVERCAST AS SEEN ON IR SAT AND WILL
STAY THAT WAY THOUGH THE NIGHT. TOOK TEMPS DOWN A FEW DEGREES AFTER
06Z WITH THE THINKING THAT ONCE SNOW STARTS FALLING SOME
EVAPORATIONAL COOLING/WET BULBING WILL TAKE PLACE LOWERING TEMPS
INTO THE LOWER 30S. LATEST HRRR AND RUC MODELS SHOW SNOW MOVING INTO
THE SOUTHERN TIER NEAR MIDNIGHT AND INTO THE REST OF WESTERN NY BY
08Z-09Z. NO IMPACTS TO THE NORTH COUNTRY UNTIL LIKELY NEAR/AFTER
SUNRISE. POP/WX GRIDS ARE INLINE WITH THIS.
PREVIOUS DISCUSSION...
LOW PRESSURE CENTERED NEAR SOUTHERN ILLINOIS THIS EVENING WILL SHIFT
NORTHEAST ACROSS THE OHIO VALLEY BY MORNING. 12Z NAM12 AND REGIONAL
GEM HAVE COME TO A CLOSER CONSENSUS AS TO THE
PLACEMENT/TIMING/INTENSITY TO A PRECIP BAND PRECEDING THE SURFACE
LOW. THESE MODELS SHOW STRONG 925-850MB FRONTOGENETIC FORCING OVER
SOUTHWESTERN AND WESTERN NY OVERNIGHT...WITHIN A LIKEWISE STRONG
WARM ADVECTION IN THESE SAME LAYERS. DEEP MOISTURE AND A DEEP OMEGA
PLUME TO ABOVE 25000FT AND A CO-LOCATED OMEGA MAXIMUM WITHIN THE
DENDRITIC GROWTH ZONE WILL MAXIMIZE THE SNOW POTENTIAL. EXPECT THIS
TO BE IN THE FAIRLY NARROW BUT INTENSE BAND LIFTING NORTHWARD ACROSS
WESTERN NY. WILL HAVE A WINTER WEATHER ADVISORY IN EFFECT FOR SNOW
TOTALS OF 4 TO 8 INCHES...SOME HEAVIER SNOW WITH RATES MORE THAN AN
INCH AN HOUR...AND THUNDER IS NOT OUT OF THE QUESTION.
THE HEAVIER SNOW BAND LIFTING NORTHWARD WILL ALSO AFFECT THE EASTERN
LAKE ONTARIO COUNTIES...LESSER IMPACT ALONG THE SOUTH SHORE OF LAKE
ONTARIO AS THE FRONTOGENETIC FORCING SLIDES AS LITTLE MORE TO THE
EAST AHEAD OF THE ADVANCING SURFACE LOW. WILL START A WINTER WEATHER
ADVISORY AT 6AM FOR JEFF/OSW/LEWIS COUNTIES WITH A 6-8 INCH MAX OF
SNOW ON THE TUG HILL.
HIGH TEMPS ON FRIDAY WILL RANGE FROM THE UPPERMOST 30S TO MID 40S
FOR WESTERN TO CENTRAL NY...THE MID 30S TO NEAR 40 FOR THE EASTERN
LAKE ONTARIO REGION AND UPPER SAINT LAWRENCE VALLEY.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
REGARDLESS OF THE UNCERTAINTY PLAGUING THE NEAR-TERM FORECAST...THE
ONE THING THAT APPEARS REASONABLY CERTAIN IS THE PROBABILITY OF
WIDESPREAD LAKE EFFECT SNOWS ACROSS WESTERN NEW YORK FRIDAY NIGHT
THROUGH MUCH OF SATURDAY. THE PROBLEMATIC SURFACE LOW WILL BE
PULLING AWAY FROM THE REGION ACROSS NORTHERN NEW ENGLAND AND
SYNOPTIC SNOWS SHOULD BE WINDING DOWN ACROSS THE NORTH COUNTRY
FRIDAY EVENING AS THE DEFORMATION BAND WEST OF THE LOW CROSSES THE
AREA.
COLDER AIR WRAPPING BEHIND THE LOW WILL FLOW ACROSS THE LAKES
FRIDAY EVENING AS 850MB TEMPS DROP TOWARDS THE -8C TO -10C RANGE
UNDER WEST/NORTHWEST FLOW AND SURFACE TEMPERATURES DROP INTO THE 20S.
WHILE THE SURFACE-850MB TEMPERATURE DIFFERENTIAL IS SOMEWHAT
MARGINAL FOR TYPICAL LAKE EFFECT EVENTS...THE LARGE SCALE SYNOPTIC
PATTERN IS CERTAINLY CONDUCIVE TO DEVELOPMENT OF LAKE EFFECT WITH A
BROAD 500MB TROUGH OVER THE REGION AND CYCLONIC FLOW AT ALL LEVELS
ALONG WITH PLENTY OF LINGERING SYNOPTIC MOISTURE THAT EXTENDS DEEP
INTO THE ATMOSPHERE. GIVEN THIS FAVORABLE SETUP...WILL GO WITH A
BROADBRUSH LES WATCH FOR ALL OF THE CWA WITH THE EXCEPTIONS OF
ONTARIO/LIVINGSTON COUNTIES WHERE CLIMATOLOGY GENERALLY RULES
AGAINST SIGNIFICANT ACCUMULATIONS. WITH THE FLOW VEERING FROM 270 TO
290/300 DEGREES...IT CURRENTLY APPEARS THAT THE MOST SIGNIFICANT
ACCUMULATIONS WILL OCCUR FROM OSWEGO/SOUTHERN LEWIS DOWN TO EASTERN
WAYNE COUNTIES OFF OF LAKE ONTARIO AND FROM SOUTHERN ERIE DOWN INTO
THE SOUTHERN TIER OFF OF LAKE ERIE. THESE AREAS HAVE THE STRONGEST
POSSIBILITY OF SEEING WARNING LEVEL SNOWS FRIDAY NIGHT THROUGH
SATURDAY NIGHT...HOWEVER GIVEN THE POTENTIAL FOR THE DEVELOPMENT OF
A LAKE HURON/GEORGIAN BAY CONNECTION...CANNOT RULE OUT AT LEAST
ADVISORY LEVEL SNOWS FROM NORTHERN ERIE COUNTY OVER TO ROCHESTER.
IN ADDITION TO DEVELOPING LAKE EFFECT SNOWS...THE ABOVE-MENTIONED
COLD ADVECTION AND TIGHT PRESSURE GRADIENT BEHIND THE EXITING
SURFACE LOW WILL ALSO BRING A PERIOD OF GUSTY WINDS. MODEL GUIDANCE
SUGGESTS THAT THE STRONGEST WINDS ALOFT...AND HENCE THE
SURFACE...WILL BE ACROSS THE GENESEE VALLEY AND FINGER LAKES
REGION...CLOSEST TO THE AREA OF GREATEST DOWNWARD MOMENTUM. BUFKIT
PROFILES INDICATE THAT WIND GUSTS MAY EXCEED ADVISORY CRITERIA WITH
MAX GUSTS IN THE NEIGHBORHOOD OF 40-50KTS ACROSS THE AFOREMENTIONED
AREAS WITH SLIGHTLY LOWER GUSTS TO THE NORTH AND WEST...MORE LIKE
35-45KTS. GIVEN THE UNCERTAINTY IN THE EXACT TRACK OF THE LOW AND
THE FACT THAT WE ARE TALKING ABOUT AN ADVISORY THAT STRADDLES THE
END OF THE THIRD INTO THE FOURTH FORECAST PERIODS...WILL HOLD OFF ON
ISSUING ANY WIND ADVISORIES FOR NOW AND LEAVE THAT TO THE NEXT SHIFT
TO MAKE THE FINAL CALL ON...WHEN THERE WILL HOPEFULLY BE GREATER
CONFIDENCE.
AFTER A WINTRY DAY SATURDAY WITH HIGHS RIGHT AROUND 30
DEGREES...MUCH MORE WHAT ONE WOULD EXPECT FOR MID TO LATE FEBRUARY.
...LAKE EFFECT SNOWS SHOULD WIND DOWN SATURDAY NIGHT AS RIDGING ALOFT
AND AT THE SURFACE BUILDS ACROSS THE EASTERN GREAT LAKES WITH ANY
LINGERING FLURRIES ENDING BY SUNDAY MORNING AS FLOW TURNS SOUTHERLY.
THIS SHOULD RESULT IN FAIRLY PLEASANT DAY ON SUNDAY WITH AT LEAST
THE AREAS WEST OF THE GENESEE VALLEY SEEING A FAIR AMOUNT OF
SUNSHINE. WARM ADVECTION ALOFT AHEAD OF A CLIPPER LOW OVER THE UPPER
MIDWEST WILL RESULT IN MID-LEVEL CLOUDINESS EAST OF THE GENESEE
VALLEY. LOOK FOR TEMPERATURES TO RUN RIGHT AROUND NORMAL FOR THIS
TIME OF YEAR SUNDAY AND SUNDAY NIGHT AS THE COLD AIR IN PLACE SLOWLY
RETREATS TO THE NORTH.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
LOOK FOR A WARM AND DRY START TO THE WEEK AS A CLIPPER LOW SLIDES
FROM THE UPPER GREAT LAKES INTO QUEBEC PLACING WESTERN NEW YORK
FIRMLY IN THE WARM SECTOR OF THE LOW UNDER BROAD SOUTHERLY FLOW. ANY
ISENTROPICALLY INDUCED PRECIP WILL OCCUR FAR TO OUR NORTH IN
CANADA...RESULTING IN DRY DAY WITH A DECENT AMOUNT OF SUNSHINE
ACROSS THE AREA HELPING HIGHS TO CLIMB WELL INTO THE 40S.
MODEL CONSENSUS SUGGESTS A DRY NIGHT TUESDAY NIGHT...HOWEVER THERE
ARE SOME DISPARITIES IN THE TEMPERATURE FORECAST BASED ON
DIFFERENCES IN THE TIMING/LOCATION OF A SURFACE LOW PROGGED TO FORM
OVER THE GREAT PLAINS SOMETIME BETWEEN MONDAY NIGHT AND TUESDAY
AFTERNOON. THE GFS IS MUCH FASTER IN DEVELOPING BROAD WARM ADVECTION
ACROSS THE OHIO VALLEY/LOWER GREAT LAKES MONDAY NIGHT AS OPPOSED TO
THE ECMWF THAT ALLOWS COLDER AIR TO FLOW ACROSS THE AREA BEFORE WARM
ADVECTION KICKS IN TUESDAY NIGHT. THIS PRESENTS A VERY SIMILAR
CONUNDRUM TO THE ONE PLAYING OUT RIGHT NOW FOR TONIGHT/S FORECAST
AND GIVEN HOW FAR OUT WE ARE TALKING ABOUT...CHANGES WILL BE VERY
MINOR...STICKING WITH SLIGHTLY ABOVE NORMAL LOWS IN THE UPPER 20S
MONDAY NIGHT.
THE AFOREMENTIONED LOW THAT DEVELOPS OVER THE MIDWEST DURING THE
EARLY PART OF NEST WEEK AND TRACKS ACROSS THE LOWER GREAT LAKES AND
EVENTUALLY ACROSS NEW YORK STATE SOMETIME DURING THE MIDDLE OF NEXT
WEEK WITH TIMING DEPENDENT ON WHICH MODEL YOU GO WITH. GIVEN THE
UNCERTAINTY ALREADY DISCUSSED AND THE LACK OF CONFIDENCE IN ANY ONE
SOLUTION...THE GRIDS FOR TUESDAY AND WEDNESDAY WILL FEATURE
BROAD-BRUSHED CHANCE POPS WITH RUNNING ABOUT 5 DEGREES ABOVE
NORMAL...WHICH IS APPROPRIATE GIVEN THE TRENDS THIS SEASON.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS LOWERING TO IFR/LIFR BY FRIDAY MORNING AS AN AREA OF
LOW PRESSURE BRINGS LOWERING CIGS AND SNOW OVERNIGHT. IR SATELLITE
AND OBS SHOWING HIGH CLOUDS IN PLACE OVER THE FORECAST AREA AHEAD OF
THE STORM SYSTEM. MVFR CIGS EXPECTED IN THE RANGE OF 04Z TO ABOUT
06Z...THEN FURTHER LOWERING TO IFR/LIFR AFTER 07Z-09Z WITH BAND OF
SNOW SHIFTING NORTH ACROSS THE FORECAST AREA. SNOW WILL BE HEAVY AT
TIMES OVER THE SOUTHERN TIER AND CHAUTAUQUA RIDGE. A TRANSITION TO
RAIN IS EXPECTED BY MID MORNING ACROSS WESTERN NY INTO THE AFTERNOON
AS THE STORM CENTER MOVES NORTH OF LAKE ONTARIO. KART WILL SEE A
LATER ARRIVAL OF SNOW...11Z-12Z AND LATER CHANGE TO RAIN IF AT ALL
FRIDAY. LAKE SNOWS MAY DEVELOP ON THE BACK SIDE OF THE STORM SYSTEM
BY 24/00Z.
OUTLOOK...
FRIDAY NIGHT...IFR/MVFR IN LAKE EFFECT SNOW.
SATURDAY...VFR...WITH IFR/MVFR IN SCATTERED SNOW SHOWERS AND AREAS
OF LAKE EFFECT SNOW EAST OF THE LAKES.
SUNDAY...VFR...SCTD LAKE EFFECT SNOW SOUTHEASTERN LAKE ONTARIO.
MONDAY...VFR.
&&
.MARINE...
A RIDGE OF HIGH PRESSURE WILL SLIDE TO THE EAST OF THE REGION
TONIGHT AS LOW PRESSURE DEEPENS AND LIFTS NORTHEASTWARD FROM THE
UPPER OHIO VALLEY. THIS LOW WILL CONTINUE ON ACROSS LAKE ERIE AND
WESTERN LAKE ONTARIO...RAISING WINDS AND WAVES AND CREATING
CONDITIONS REQUIRING SMALL CRAFT ADVISORIES FOR ALL NEARSHORE WATERS
ON BOTH LAKES.
THE LOW WILL MOVE INTO NEW ENGLAND ON FRIDAY NIGHT...BRINGING A
DECENT NORTHWESTERLY FLOW ACROSS ALL THE LAKES...WITH CONTINUED
SMALL CRAFT CONDITIONS THROUGH SUNDAY MORNING.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW WATCH FROM FRIDAY EVENING THROUGH SUNDAY
MORNING FOR NYZ001>008-010>012-019>021-085.
WINTER WEATHER ADVISORY FROM 6 AM TO 7 PM EST FRIDAY FOR
NYZ006>008.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM EST
FRIDAY FOR NYZ010>014-019>021-085.
MARINE...SMALL CRAFT ADVISORY FROM NOON TO 11 PM EST FRIDAY FOR LEZ040-
041.
SMALL CRAFT ADVISORY FROM 6 PM FRIDAY TO 6 AM EST
SUNDAY FOR LOZ043>045.
SMALL CRAFT ADVISORY FROM 1 AM FRIDAY TO 6 AM EST SUNDAY
FOR LOZ042.
&&
$$
SYNOPSIS...SMITH/WCH
NEAR TERM...SMITH/WCH
SHORT TERM...WOOD
LONG TERM...WOOD
AVIATION...SMITH/WCH
MARINE...WCH
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1255 AM EST WED FEB 22 2012
.SYNOPSIS...
HIGH PRESSURE WILL MOVE INTO THE AREA BEHIND A DEPARTING COLD FRONT.
A STRONGER FRONT IS EXPECTED TO MOVE INTO THE CAROLINAS EARLY ON
FRIDAY. HIGH PRESSURE WILL THEN RETURN OVER THE WEEKEND AND LINGER
INTO EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH TODAY/...
RELATIVELY QUIET AT MIDNIGHT ACROSS THE REGION. MAIN CONCERN IS THE
DEVELOPMENT OF LOW STRATUS FROM THE SW DURING THE PRE-DAWN
HOURS...AS CONSIDERABLY HIGHER DEWPT AIR IS SLOWLY CREEPING NWD FROM
THE GULFMEX. NOTHING SIGNIFICANT SHOWED UP ON SATELLITE IMAGERY
YET...SO THE SKY COVER WAS KEPT MOSTLY CLEAR THROUGH SUNRISE. TEMPS
WILL BE TWEAKED FOR THE RECENT OBS TREND AS WELL.
REMAINDER OF PREVIOUS DISCUSSION...
AS OF 950 PM TUE...THE HRRR AND WORKSTATION WRF...ALONG WITH THE 18
UTC NAM BUFKIT...CONTINUE TO SHOW STRATUS DEVELOPING OVER NE
GA...THE UPSTATE AND THE SRN NC PIEDMONT LATE TONIGHT. THIS WILL BE
MORE IMPORTANT FOR TAF GENERATION PURPOSES LATER TONIGHT.
OTHERWISE...I/VE RAISED DEWPOINTS ACROSS THE SOUTH ONCE AGAIN. THE
WINDS HAVE DECOUPLED QUICKLY THIS EVENING...BUT SHOULD INCREASE INTO
THE 4 TO 6 KT RANGE LATER TONIGHT AND THE LLVL JET STRENGTHENS TO
AROUND 30 KTS OVER THE FA.
A SHORT WAVE ENTERS THE AREA WED AFTERNOON AS MID LEVEL FLOW BECOMES
A LITTLE MORE AMPLIFIED. ANOTHER SLIGHTLY STRONGER FRONT WILL MOVE
INTO THE AREA AS WELL. FORCING AND MOISTURE IS BETTER WITH THIS
SYSTEM. THAT SAID...THE FORCING IS NOT VERY STRONG WITH ONLY WEAK
UPPER DIVERGENCE. THE MOISTURE IS NOT VERY COPIOUS EITHER. STILL...
IT APPEARS THAT THEY WILL BE ENUF FOR GOOD CHC POP TO DEVELOP OVER
THE MTNS. POP DROPS OFF TO SLIGHT CHC SOUTH OF I-85 AWAY FROM THE
BEST MOISTURE AND FORCING. INSTABILITY IS ON THE UPSWING DURING THE
AFTERNOON...BUT IT REMAINS QUESTIONABLE WHETHER IT BECOMES STRONG
ENUF FOR ANY TSRA TO DEVELOP. THEREFORE...HAVE CONTINUED THE PREV
TREND OF NO TS MENTION FOR NOW. SHOULD BE ANOTHER GUSTY AFTERNOON AS
DEEP MIXING TAPS RELATIVELY STRONG LOW LEVEL FLOW. IN FACT...IT
COULD BE STRONG ENUF FOR A LAKE WIND ADV. WILL LET NEXT SHIFT MAKE
THAT DECISION AS THE MAGNITUDE IS STILL IN QUESTION. HIGHS WILL BE 5
TO 10 DEGREES ABOVE NORMAL.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY/...
AS OF 230 PM TUESDAY...A WARM AND MOIST AIR MASS WILL DEVELOP OVER
THE REGION DURING THE MID WEEK. WEDNESDAY EVENING...A SHORT WAVE IS
EXPECTED TO RIPPLE WITHIN A LONGWAVE TROF AXIS ACROSS THE SOUTHERN
APPALACHIAN REGION DURING THE EARLY EVENING HOURS. GUSTY SOUTHWEST
WINDS ARE FORECAST TO BRING RISING DEWPOINTS ACROSS THE FORECAST
AREA...GENERALLY RANGING IN THE MID TO UPPER 40S. AN AREA OF
TSRA/SHRA IS EXPECTED TO DEVELOP DURING THE AFTERNOON UPSTREAM OF
THE REGION...STEERING FLOW WILL TRANSPORT THE CONVECTION NORTHEAST
ACROSS GEORGIA AND THE WESTERN CAROLINAS. DURING THE EVENING
HOURS...FORECAST SOUNDINGS INDICATE THAT CAPE VALUES WILL RANGE FROM
100 TO 400 J/KG ACROSS THE CWA. IN ADDITION...SWEAT VALUES WILL PEAK
BETWEEN 300-400 WITH EHI VALUES AROUND 1...THE CORE OF A H3 140 KT
JET WILL REMAIN ACROSS THE MIDLANDS AND COASTAL AREAS. GIVEN THE
BROAD FIELD OF WEAK INSTABILITY AND STRONG WIND FIELDS...IT IS
REASONABLE TO EXPECT ORGANIZED MCS TO SURVIVE INTO THE EVENING HOURS
ACROSS THE CWA. I WILL MAINTAIN CHC POPS ACROSS THE MTNS AND
FOOTHILLS...SCHC EAST OF I-85. THE POTENTIAL EXIST THAT ANY
ORGANIZED CONVECTION COULD PRODUCE DAMAGING WINDS DURING THE
EVENING...SUPPORTED BY SPC DY2 SLIGHT RISK AREA. I WILL HIGHLIGHT
THE RISK FOR DAMAGING TSRA WINDS IN THE HWO.
THROUGH THE REST OF WEDNESDAY NIGHT...ONGOING SOUTHWEST WINDS AND
THICK SKY COVER WILL KEEP TEMPERATURES MILD OVERNIGHT. USING A BLEND
OF GUIDANCE...I WILL FORECAST LOWS FROM THE L40S ACROSS THE MTNS TO
L50S EAST.
THURSDAY...PRESSURE GRADIENT ACROSS THE FORECAST AREA WILL REMAIN
BETWEEN 3 TO 4 MBS. FORECAST SOUNDINGS INDICATE THE MIXING MAY
REACH UP TO H85 DURING THE AFTERNOON. SOUTHWEST WINDS WILL LIKELY
INCREASE THROUGH THE DAY...PEAKING BETWEEN 15 TO 20 KTS WITH GUSTS
TO 25 TO 30 KTS. THESE WINDS WILL REINFORCE THE WARM AND MOIST AIR
MASS ACROSS THE REGION...WITH DEWPOINTS REMAINING WELL INTO THE 40S.
H85 TEMPS MAY REACH ABOVE 10C DURING THE AFTERNOON AS A COLD FRONT
PUSHES INTO MIDDLE TN. MOS CONSENSUS SUPPORTS HIGH TEMPERATURES IN
THE U60S ACROSS THE MTNS VALLEYS TO LOW TO MID 70S EAST...OR WITHIN
A COUPLE OF DEGREES OF RECORD HIGHS.
THURSDAY NIGHT...NAM AND GFS INDICATE THAT COLD FRONT WILL SWEEP
ACROSS THE SOUTHERN APPALACHIAN REGION DURING THE LATE NIGHT HOURS.
WIND FIELDS ALONG AND AHEAD OF THE FRONT BECOME STRONG WITH 0 TO 1
KM HELICITY EXCEEDING 300 M2/S2. NAM CAPE SHOWS THAT A BAND OF WEAK
CAPE WILL REMAIN ALONG AND AHEAD OF THE FRONT. THIS ENVIRONMENT MAY
SUPPORT ONGOING GA/TN MCS TO TRACK ACROSS THE REGION DURING THE
NIGHT. THESE SITUATIONS TYPICALLY BRING TSRA EAST QUICKER THAN
MODEL RATES...BUT EVEN USING THE MORE STABLE GUIDANCE IT APPEARS
THAT SVR WINDS ARE POSSIBLE. WE WILL ALSO HIGHLIGHT THIS EVENT IN
THE HWO. MIN TEMPERATURES ARE FORECAST TO RANGE FROM U40S ACROSS THE
MTN VALLEYS TO LOW TO MID 50S EAST.
FRIDAY...WINDS WILL VEER WEST TO EVENTUALLY NORTHWEST IN THE WAKE OF
THE COLD FRONT. I WILL INDICATE DECREASING POPS AND SKY WITH THE
PASSAGE OF THE FRONT. MODELS INDICATE THAT H85 TEMPS WILL FALL
THROUGH THE DAY...WITH TEMPS COOLING BETWEEN 8 TO 10 C DURING THE
DAYLIGHT HOURS. I WILL WILL INDICATE A MID DAY HIGH IN THE U50S
ACROSS THE MTNS TO U60S EAST...THEN GRADUAL COOLING THROUGH THE
AFTERNOON.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 2 PM TUESDAY...THE GLOBAL MODELS ARE HAVING TYPICAL ISSUES
WITH THE SPLIT FLOW REGIME IN PLACE AT THE BEGINNING OF THE PERIOD.
THEREFORE...CONFIDENCE IN THE MEDIUM RANGE FORECAST IS MUCH LOWER
THAN USUAL. THE MAIN PROBLEMS ARE IN THE SOUTHERN STREAM...
SPECIFICALLY IN TIMING THE KICKING OUT OF THE UPPER LOW THAT IS
CURRENTLY OVER THE BAJA AREA. THE 00Z ECMWF KICKS THIS ENERGY OUT
OVER THE SOUTHEAST FRIDAY (ABOUT 24 HOURS LATER THAN YESTERDAYS
RUNS). MEANWHILE...THE GFS DOESNT DO THIS UNTIL SUNDAY NIGHT. THE
MODELS HAVE BEEN UP TO THESE TYPES OF SHENANIGANS FOR SEVERAL DAYS
NOW WITH REGARD TO THIS SOUTHERN STREAM ENERGY AND WHETHER/WHEN TO
TRANSITION TO A PHASED FLOW REGIME. WE/VE OPTED TO STOP PRETENDING
THAT WE OR THE MODELS HAVE ANY CLUE WHAT/S GOING TO HAPPEN PAST THE
SHORT TERM PERIOD. POPS WILL THEREFORE BE HELD BELOW CHANCE THROUGH
THE MEDIUM RANGE...WHILE NEAR-NORMAL TEMPS WILL BE FORECAST IN THE
WAKE OF FRIDAYS FROPA.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT AND ELSEWHERE...THE MAIN ISSUE IS THE POSSIBILITY OF LOW
STRATUS DEVELOPING IN A LIGHT RETURN FLOW FROM THE SW. A PLUME OF
HIGHER DEWPT AIR WAS MOVING NWD FROM THE GULFMEX AS OF 05Z. PREVIOUS
GUIDANCE SHOWED THE POSSIBILITY OF SOME LOW STRATUS DEVELOPING
DURING THE EARLY MORNING HOURS. IT HAS NOT DEVELOPED YET. THE 00Z
RUN OF THE NAM HAS BACKED OFF A BIT...SO THE TAFS WILL AS WELL...
UNTIL SOME SIGN OF DEVELOPMENT IS SEEN. CONFIDENCE ONLY ABOUT 40 PCT
THAT STRATUS WILL DEVELOP...SO IT WAS LEFT OUT. OTHERWISE...LOW
LEVEL MOISTURE WILL INCREASE TODAY AS WILL SW FLOW AHEAD OF A
SURFACE BOUNDARY APPROACHING FROM THE WEST. THIS RESULTS IN A PERIOD
OF GUSTY WINDS AT MOST TAF SITES AND AN UNCOMMON CROSS VALLEY WIND
AT KAVL FOR THE AFTERNOON. THE MODELS SUGGEST CONVECTIVE DEVELOPMENT
IN THE GREAT VALLEY OF TN THIS AFTERNOON...WITH THE CONVECTION
DEVELOPING ACROSS THE MTNS IN THE AFTERNOON AND INTO THE PIEDMONT IN
THE EVENING. CONFIDENCE TOO LOW TO INCLUDE THIS IN THE TAFS WITH
THIS ISSUANCE BUT IT WILL BE REVISITED WITH THE NEXT ONE. THE
MOISTENING BOUNDARY LAYER MAY VERY WELL RESULT IN AN MVFR CLOUD DECK
BY LATE EVENING.
OUTLOOK...PCPN CHANCES WILL CONTINUE THRU THURSDAY. CEILING AND VIS
RESTRICTIONS ARE POSSIBLE AROUND CONVECTION DURING THIS TIME. GUSTY
SW WINDS WILL DEVELOP AGAIN ON THU. LOW PRESSURE WILL DEVELOP OVER
THE DEEP SOUTH THU NIGHT AND FRI. WIDESPREAD LOW CIGS AND PCPN ARE
EXPECTED AS THE LOW DEVELOPS. DRIER AND COLDER WEATHER WILL FOLLOW
FOR THE WEEKEND.
AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...
WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.
&&
$$
SYNOPSIS...PAT
NEAR TERM...MCAVOY/PM
SHORT TERM...NED
LONG TERM...JDL
AVIATION...PM
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1136 AM PST Wed Feb 22 2012
.SYNOPSIS...
A strong cold front will move through the Pacific Northwest this
morning. Strong winds will develop behind the cold front, and gusty
winds will persist through early this evening. Winds will subside
tonight. The weather on Thursday will be quiet. The threat for snow
will return Friday night into Saturday with the arrival of a cool
low pressure system.
&&
.DISCUSSION...
rest of today...Surface cold front now nearly through the entire
forecast area as attested to by strong pressure rises over all of
eastern Washington and north Idaho. The air mass behind the cold
front has destabilized nicely as cooling aloft outpaces the
cooling or slight warming near the ground. RUC CAPE values have
climbed to anywhere from 100-300 j/KG over the NE corner of
Washington into the Lake Pend Oreille area...which has resulted a
growing shower trend over that area. The best instability is
expected to slide into the central Panhandle later this afternoon
and that`s where we expect to see the most numerous showers by late
this afternoon. The predominate precipitation type will be a mix
of rain and snow in the heavier showers over the valleys...with
snow over the mountains. Based on above freezing surface
temperatures and even warmer roads...valley accumulations will not
be an issue.
The other story for today will be the wind. All Mesoscale models
have transitioned the Inland NW to a cold air advection regime at
850 mb with strong downward momentum expected through the
remainder of the afternoon. The strongest 850 mb winds...ranging
from 40-50kts...will generally impact locations south of a line
from the Waterville Plateau to the southern half of the Palouse.
Current wind highlights cover the situation quite well as the
strongest winds will occur over the Palouse...Blue Mountains...and
Lewiston area. Not sure if the strongest winds under this jet will
mix down into the Columbia Basin...but if so we could see wind
gusts to 50 MPH...which is just below high wind warning criteria.
The winds at 850 mbs...and thus at the ground should peak by early
afternoon. Farther north...there is the possibility that some of
the showers could mix some higher winds down to the ground...but
that should be rather spotty. FX
&&
.AVIATION...
18Z TAFs: VFR conditions are expected at all sites through the
forecast period. The main story will be the wind. Strongest speeds
will likely impact KPUW and KLWS with gusts approaching 50
MPH...but shear will not be an issue due to deep mixing through
the boundary layer. Winds will begin to taper off during the
evening. FX
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 48 28 40 24 40 28 / 10 10 10 10 30 70
Coeur d`Alene 48 28 40 23 40 28 / 30 10 10 10 40 70
Pullman 52 29 40 26 41 31 / 40 10 10 0 10 70
Lewiston 59 34 48 30 48 34 / 20 10 10 0 10 50
Colville 47 25 44 21 42 25 / 40 10 0 10 60 70
Sandpoint 48 27 39 22 37 25 / 70 20 10 10 50 80
Kellogg 45 28 39 23 40 26 / 100 40 40 10 30 80
Moses Lake 58 29 47 25 45 28 / 10 0 0 0 20 60
Wenatchee 52 30 45 27 42 28 / 10 10 0 10 30 60
Omak 54 23 40 19 41 22 / 10 0 0 10 60 60
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...Wind Advisory until 10 PM PST this evening for Coeur d`Alene
Area-Northern Panhandle.
High Wind Warning until 4 PM PST this afternoon for Idaho
Palouse-Lewiston Area.
Wind Advisory until 7 PM PST this evening for Lewis and Southern
Nez Perce Counties.
WA...Wind Advisory until 10 PM PST this evening for Spokane Area-
Upper Columbia Basin.
High Wind Warning until 4 PM PST this afternoon for Lower
Garfield and Asotin Counties-Washington Palouse.
Wind Advisory until 7 PM PST this evening for Moses Lake Area-
Waterville Plateau-Wenatchee Area.
&&
$$
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
930 PM PST THU FEB 23 2012
...UPDATED AVIATION DISCUSSION...
.SYNOPSIS...
HIGH PRESSURE WILL PERSIST INTO FRIDAY WITH GUSTY OFFSHORE WINDS
AND ABOVE NORMAL TEMPERATURES. A COUPLE OF WEAK LOW PRESSURE
SYSTEMS WILL BRING MUCH COOLER TEMPERATURES AND BREEZY WINDS OVER
THE WEEKEND. TEMPERATURES WILL CONTINUE TO DROP THE FIRST PART OF
NEXT WEEK...COUPLED WITH STRONGER ONSHORE BREEZES.
&&
.UPDATE...
AS HIGH LEVEL MOISTURE CLEARS OUT...THE LATEST FOG PRODUCT
IMAGERY IS REVEALING A DEVELOPING MARINE LAYER DECK ALONG THE
ORANGE COUNTY COAST AND MOVING NORTH. WITH SOME WEAKENING OF THE
OFFSHORE GRADIENTS AND ENOUGH OF A SEA BREEZE THIS AFTERNOON NEAR
THE COAST...IT MAKES SENSE THAT A MARINE LAYER COULD FORM. WITH
NEAR NEUTRAL SURFACE PRESSURE GRADIENTS THIS AFTERNOON...ANY FOG
WILL LIKELY BE DENSE AND PATCHY LOW CLOUDS AND DENSE FOG WERE
ADDED TO THE PACKAGE FOR TONIGHT ACROSS THE LOS ANGELES COUNTY
COAST.
THERE IS A CHANCE THAT LOW CLOUDS AND FOG COULD LINGER AFTER
SUNRISE ON FRIDAY...BUT ANY ADDITION FOR THE MORNING PERIOD ON
FRIDAY WILL BE TABLED FOR NOW. NAM-WRF AND 13-KM RUC SOLUTIONS
SUGGEST THAT THE LOW-LEVEL MOISTURE SCOURS LATE TONIGHT AND INTO
FRIDAY MORNING.
A MARGINAL WIND ADVISORY REMAINS IN EFFECT...STARTING AT 10 PM
THIS EVENING. 00Z MODEL SOLUTIONS ARE BACKING OFF TO A LATER
START TIME TONIGHT...AROUND 2 AM OR SO IN THE LATEST NAM-WRF
SOLUTIONS. WITH THE LATEST 13-KM RUC SOLUTIONS FOLLOWING
SUIT...THE START TIME MAY BE BUMPED BACK AT THE NEXT WIND ADVISORY
UPDATE. SOME CONCERN EXISTS THAT THE VENTURA COUNTY COAST MAY NOT
REACH CRITERIA ACROSS A MORE WIDESPREAD AREA. WITH A PERIOD
AROUND 7 AM WHEN THE STRONGER WIND ALOFT COULD MIX DOWN...THE
ADVISORY WILL LIKELY BE CONTINUED FOR NOW.
WITH A TAD MORE MIXING WITH THE WIND AND SOME COOL AIR ADVECTION
PUSHING INTO THE AREA...THE AIR MASS SHOULD COOL SOME ON FRIDAY.
950 MB AND BOUNDARY LAYER TEMPERATURES CONTINUE TO COOL SLIGHTLY
ACROSS THE AREA ON FRIDAY. WITH MODEL DATA STILL ARRIVING THIS
EVENING...A FEW TWEAKS MAY BE PERFORMED FOR TEMPERATURES ON
FRIDAY...BUT NO MAJOR WHOLESALE CHANGES ARE PLANNED.
&&
.PREV DISCUSSION...
SHORT TERM...ONSHORE FLOW WILL INCREASE FRIDAY NIGHT INTO
SATURDAY AS A LOW PRESSURE AREA MOVES INTO THE PAC NW AND SURFACE
PRESSURE FALL ACROSS THE INTERIOR. AS A RESULT, MOST AREAS WILL
SEE A SOLID 5-10 DEGREE DROP IN HIGHS SAT. MAY ALSO SEE SOME
PATCHY MARINE LYR CLOUDS DEVELOPING ACROSS COASTAL LA/VENTURA
COUNTIES EARLY SAT MORNING.
NORTH TO NORTHWEST FLOW WILL BE INCREASING SATURDAY NIGHT BEHIND THE
PAC NW TROF, LIKELY GENERATING AT LEAST ADVISORY LEVEL WINDS ACROSS
THE MOUNTAINS (ESPECIALLY I5 CORRIDOR REGION) AND SOUTHERN SBA
COUNTY.
A SECOND AND SOMEWHAT DEEPER TROF WILL MOVE INTO THE WEST COAST
SUNDAY, BRINGING EVEN COOLER TEMPERATURES TO THE AREA. SOME OF THE
NORTHWEST FLOW THROUGH THE MOUNTAINS WILL FILTER DOWN INTO THE
VALLEYS SUNDAY RESULTING IN BREEZY CONDITIONS IN MANY AREAS,
ESPECIALLY THE ANTELOPE VALLEY WHICH MAY SEE ADVISORY LEVEL WINDS BY
AFTERNOON. THE COLD AIR ADVECTION AND NORTHWEST FLOW WILL LIKELY
WIPE OUT ANY MARINE LYR CLOUDS FROM THE DAY BEFORE BUT HIGHS AT
LOWER ELEVATIONS WILL LIKELY TOP OUT IN THE MID 60S AT BEST.
LONG TERM (MON-THU)...FAIRLY COOL PATTERN AT LEAST FOR THE FIRST
HALF OF THE WEEK AS A COUPLE OF COLD LOW PRESSURE SYSTEMS DROP SOUTH
THROUGH OREGON AND NEVADA. THE ECMWF IS A LITTLE FURTHER WEST AND
SHARPER WITH THE TROF AXIS, BUT STILL TOO DRY FOR ANY WIDESPREAD
PRECIP. STRONG ONSHORE FLOW WILL CONTINUE MONDAY WITH ADVISORY LEVEL
WINDS POSSIBLE ACROSS THE ANTELOPE VALLEY. ALTHOUGH THE INVERSION
WILL BE VERY WEAK, THE GFS AND ECMWF ARE SHOWING JUST ENOUGH
MOISTURE BELOW 850 MB TO SUGGEST THE POSSIBILITY OF SOME
STRATOCUMULUS DEVELOPMENT ACROSS THE EASTERN PORTION OF LA COUNTY
AND AREAS SOUTH AND EAST MONDAY INTO EARLY TUESDAY. IN FACT, IF THE
ECMWF IS CORRECT THERE COULD BE ENOUGH ENERGY TO SQUEEZE OUT SOME
DRIZZLE OR SPRINKLES ACROSS ERN LA COUNTY MONDAY INTO MONDAY
EVENING. FOR NOW THOUGH WILL JUST GO WITH A PARTLY CLOUDY AND COOL
FORECAST.
SOME IMPROVEMENT IN TEMPERATURES EXPECTED FOR THE MIDDLE OF NEXT
WEEK BUT FAIRLY MINIMAL AS WEAK CYCLONIC FLOW REMAINS ACROSS
SOUTHWEST CALIFORNIA WITH JUST MINOR INCREASE IN
HEIGHTS/THICKNESSES. THUS, A MUCH COOLER PATTERN NEXT WEEK THAN
WE`VE SEEN BUT STILL VERY LITTLE CHANCE OF PRECIPITATION. IN FACT,
LONGER RANGE MODELS SUGGESTING A RETURN TO WARMER CONDITIONS LATER
NEXT WEEK INTO NEXT WEEKEND AS THE ERN PACIFIC RIDGE RETURNS AND
BUILDS OVER THE WEST COAST.
&&
.AVIATION...24/0530Z...
OVERALL...VFR CONDS ARE EXPECTED AT MOST AIRFIELDS THROUGH THE
PERIOD. THE ONLY EXCEPTION WILL BE THE LAX COUNTY COAST WHERE SOME
IFR/LIFR CONDS WILL CONTINUE THROUGH EARLY FRIDAY MORNING. WITH THE
DEVELOPING OFFSHORE FLOW...WILL EXPECT THESE CIG/VSBYS RESTRICTIONS
AT KLGB/KLAX TO IMPROVE NEAR SUNRISE.
THE OFFSHORE WINDS WILL PRODUCE SOME LLWS/TURBULENCE ISSUES ACROSS
THE MOUNTAINS/VALLEYS AND COASTAL PLAIN THROUGH FRIDAY MORNING.
KLAX...LOW CONFIDENCE IN 06Z TAF. THERE IS A 40% CHANCE THE IFR/LIFR
CONDS DO NOT REACH THE AIRFIELD. IF THE IFR/LIFR CONDS DO DEVELOP
THERE IS A 50% CHANCE THE IFR/LIFR CONDS COULD LINGER FOR A COUPLE
HOURS BEYOND 13Z.
KBUR...HIGH CONFIDENCE IN 06Z TAF.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY (SEE LAXNPWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH SURF ADVISORY (SEE LAXCFWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).
&&
$$
PUBLIC...HALL/WOFFORD
AVIATION...RAT
SYNOPSIS...B/HALL
WWW.WEATHER.GOV/LOSANGELES
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
846 PM PST THU FEB 23 2012
.SYNOPSIS...
HIGH PRESSURE WILL PERSIST INTO FRIDAY WITH GUSTY OFFSHORE WINDS
AND ABOVE NORMAL TEMPERATURES. A COUPLE OF WEAK LOW PRESSURE
SYSTEMS WILL BRING MUCH COOLER TEMPERATURES AND BREEZY WINDS OVER
THE WEEKEND. TEMPERATURES WILL CONTINUE TO DROP THE FIRST PART OF
NEXT WEEK...COUPLED WITH STRONGER ONSHORE BREEZES.
&&
.UPDATE...
AS HIGH LEVEL MOISTURE CLEARS OUT...THE LATEST FOG PRODUCT
IMAGERY IS REVEALING A DEVELOPING MARINE LAYER DECK ALONG THE
ORANGE COUNTY COAST AND MOVING NORTH. WITH SOME WEAKENING OF THE
OFFSHORE GRADIENTS AND ENOUGH OF A SEA BREEZE THIS AFTERNOON NEAR
THE COAST...IT MAKES SENSE THAT A MARINE LAYER COULD FORM. WITH
NEAR NEUTRAL SURFACE PRESSURE GRADIENTS THIS AFTERNOON...ANY FOG
WILL LIKELY BE DENSE AND PATCHY LOW CLOUDS AND DENSE FOG WERE
ADDED TO THE PACKAGE FOR TONIGHT ACROSS THE LOS ANGELES COUNTY
COAST.
THERE IS A CHANCE THAT LOW CLOUDS AND FOG COULD LINGER AFTER
SUNRISE ON FRIDAY...BUT ANY ADDITION FOR THE MORNING PERIOD ON
FRIDAY WILL BE TABLED FOR NOW. NAM-WRF AND 13-KM RUC SOLUTIONS
SUGGEST THAT THE LOW-LEVEL MOISTURE SCOURS LATE TONIGHT AND INTO
FRIDAY MORNING.
A MARGINAL WIND ADVISORY REMAINS IN EFFECT...STARTING AT 10 PM
THIS EVENING. 00Z MODEL SOLUTIONS ARE BACKING OFF TO A LATER
START TIME TONIGHT...AROUND 2 AM OR SO IN THE LATEST NAM-WRF
SOLUTIONS. WITH THE LATEST 13-KM RUC SOLUTIONS FOLLOWING
SUIT...THE START TIME MAY BE BUMPED BACK AT THE NEXT WIND ADVISORY
UPDATE. SOME CONCERN EXISTS THAT THE VENTURA COUNTY COAST MAY NOT
REACH CRITERIA ACROSS A MORE WIDESPREAD AREA. WITH A PERIOD
AROUND 7 AM WHEN THE STRONGER WIND ALOFT COULD MIX DOWN...THE
ADVISORY WILL LIKELY BE CONTINUED FOR NOW.
WITH A TAD MORE MIXING WITH THE WIND AND SOME COOL AIR ADVECTION
PUSHING INTO THE AREA...THE AIR MASS SHOULD COOL SOME ON FRIDAY.
950 MB AND BOUNDARY LAYER TEMPERATURES CONTINUE TO COOL SLIGHTLY
ACROSS THE AREA ON FRIDAY. WITH MODEL DATA STILL ARRIVING THIS
EVENING...A FEW TWEAKS MAY BE PERFORMED FOR TEMPERATURES ON
FRIDAY...BUT NO MAJOR WHOLESALE CHANGES ARE PLANNED.
&&
.PREV DISCUSSION...
SHORT TERM...ONSHORE FLOW WILL INCREASE FRIDAY NIGHT INTO
SATURDAY AS A LOW PRESSURE AREA MOVES INTO THE PAC NW AND SURFACE
PRESSURE FALL ACROSS THE INTERIOR. AS A RESULT, MOST AREAS WILL
SEE A SOLID 5-10 DEGREE DROP IN HIGHS SAT. MAY ALSO SEE SOME
PATCHY MARINE LYR CLOUDS DEVELOPING ACROSS COASTAL LA/VENTURA
COUNTIES EARLY SAT MORNING.
NORTH TO NORTHWEST FLOW WILL BE INCREASING SATURDAY NIGHT BEHIND THE
PAC NW TROF, LIKELY GENERATING AT LEAST ADVISORY LEVEL WINDS ACROSS
THE MOUNTAINS (ESPECIALLY I5 CORRIDOR REGION) AND SOUTHERN SBA
COUNTY.
A SECOND AND SOMEWHAT DEEPER TROF WILL MOVE INTO THE WEST COAST
SUNDAY, BRINGING EVEN COOLER TEMPERATURES TO THE AREA. SOME OF THE
NORTHWEST FLOW THROUGH THE MOUNTAINS WILL FILTER DOWN INTO THE
VALLEYS SUNDAY RESULTING IN BREEZY CONDITIONS IN MANY AREAS,
ESPECIALLY THE ANTELOPE VALLEY WHICH MAY SEE ADVISORY LEVEL WINDS BY
AFTERNOON. THE COLD AIR ADVECTION AND NORTHWEST FLOW WILL LIKELY
WIPE OUT ANY MARINE LYR CLOUDS FROM THE DAY BEFORE BUT HIGHS AT
LOWER ELEVATIONS WILL LIKELY TOP OUT IN THE MID 60S AT BEST.
LONG TERM (MON-THU)...FAIRLY COOL PATTERN AT LEAST FOR THE FIRST
HALF OF THE WEEK AS A COUPLE OF COLD LOW PRESSURE SYSTEMS DROP SOUTH
THROUGH OREGON AND NEVADA. THE ECMWF IS A LITTLE FURTHER WEST AND
SHARPER WITH THE TROF AXIS, BUT STILL TOO DRY FOR ANY WIDESPREAD
PRECIP. STRONG ONSHORE FLOW WILL CONTINUE MONDAY WITH ADVISORY LEVEL
WINDS POSSIBLE ACROSS THE ANTELOPE VALLEY. ALTHOUGH THE INVERSION
WILL BE VERY WEAK, THE GFS AND ECMWF ARE SHOWING JUST ENOUGH
MOISTURE BELOW 850 MB TO SUGGEST THE POSSIBILITY OF SOME
STRATOCUMULUS DEVELOPMENT ACROSS THE EASTERN PORTION OF LA COUNTY
AND AREAS SOUTH AND EAST MONDAY INTO EARLY TUESDAY. IN FACT, IF THE
ECMWF IS CORRECT THERE COULD BE ENOUGH ENERGY TO SQUEEZE OUT SOME
DRIZZLE OR SPRINKLES ACROSS ERN LA COUNTY MONDAY INTO MONDAY
EVENING. FOR NOW THOUGH WILL JUST GO WITH A PARTLY CLOUDY AND COOL
FORECAST.
SOME IMPROVEMENT IN TEMPERATURES EXPECTED FOR THE MIDDLE OF NEXT
WEEK BUT FAIRLY MINIMAL AS WEAK CYCLONIC FLOW REMAINS ACROSS
SOUTHWEST CALIFORNIA WITH JUST MINOR INCREASE IN
HEIGHTS/THICKNESSES. THUS, A MUCH COOLER PATTERN NEXT WEEK THAN
WE`VE SEEN BUT STILL VERY LITTLE CHANCE OF PRECIPITATION. IN FACT,
LONGER RANGE MODELS SUGGESTING A RETURN TO WARMER CONDITIONS LATER
NEXT WEEK INTO NEXT WEEKEND AS THE ERN PACIFIC RIDGE RETURNS AND
BUILDS OVER THE WEST COAST.
&&
.AVIATION...24/0000Z.
VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD EXCEPT FOR A
CHANCE OF MVFR CONDITIONS BETWEEN 08Z AND 16Z AT KSBA AND KSMX...AND
A SLIGHT CHANCE OF VLIFR TO LIFR CONDITIONS AT LOS ANGELES AND SANTA
BARBARA COUNTY COASTAL TERMINALS. PERIODS OF LOW LEVEL WIND SHEAR
AND TURBULENCE WILL DEVELOP AFTER 04Z TONIGHT AT LOS ANGELES VALLEY
AND VENTURA COUNTY TERMINALS.
KLAX...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD. BETWEEN
08Z AND 16Z TONIGHT...THERE IS A 20 PERCENT CHANCE OF VLIFR TO LIFR
CONDITIONS.
KBUR...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD. PERIODS OF
MODERATE LOW-LEVEL WIND SHEAR AND TURBULENCE WILL DEVELOP BETWEEN
04Z AND 10Z TONIGHT...WITH A CHANCE OF OCCASIONAL MODERATE TO STRONG
WIND SHEAR AND TURBULENCE BETWEEN 10Z AND 16Z FRIDAY.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY (SEE LAXNPWLOX).
SMALL CRAFT ADVISORY (SEE LAXMWWLOX).
HIGH SURF ADVISORY (SEE LAXCFWLOX).
HIGH RIP CURRENT RISK (SEE LAXSRFLOX).
&&
$$
PUBLIC...HALL/WOFFORD
AVIATION...HALL
SYNOPSIS...B/HALL
WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS NEW YORK NY
458 AM EST FRI FEB 24 2012
.SYNOPSIS...
A POTENT STORM SYSTEM APPROACHES FROM THE WEST TODAY...WITH AN
ASSOCIATED COASTAL LOW TRACKING JUST TO OUR SOUTH THIS
EVENING...THEN ON NORTHEAST INTO THE CANADIAN MARITIMES THROUGH
SATURDAY. LOW PRESSURE NORTHEAST OF THE AREA DEPARTS SATURDAY
NIGHT...THEN HIGH PRESSURE BUILDS THROUGH THE REGION OVER THE
START OF THE NEW WEEK. LOW PRESSURE PASSING TO THE NORTH WILL DRAG
A WARM FRONT THROUGH THE REGION LATE MONDAY...FOLLOWED BY A COLD
FRONT MONDAY NIGHT. HIGH PRESSURE BRIEFLY RETURNS ON
TUESDAY...FOLLOWED BY A STORM SYSTEM FOR THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
INITIAL BURST OF WARM ADVECTION PRECIPITATION PUSHING THROUGH
REGION WITH SOME ACCUMULATING SNOW ACROSS NORTHERN ZONES...AMOUNTS
ON A ZONE BASIS WILL AVERAGE LESS THAN 3 INCHES...SO AM ADDRESSING
WITH SPECIAL WEATHER STATEMENTS. ALSO HAVE HAD SOME REPORTS OF
SLEET MIXED IN AT TIMES ACROSS SOUTHERN ZONES. EXPECT ALL
PRECIPITATION TO CHANGE TO ALL RAIN BY MID MORNING FROM S TO N AS
WARMER AIR MOVES IN ALOFT.
850 WARM FRONT LIFTS TO OUR NORTH BY MIDDAY...WITH LIGHT
RAIN/DRIZZLE IN ITS WAKE. SHOWERS MOVE INTO FAR WESTERN ZONES LATE
THIS AFTERNOON AHEAD OF AN OCCLUDED FRONT.
EXPECT THE SURFACE WARM FRONT EXPECTED TO STAY TO THE S OF LONG
ISLAND TODAY PER NAM/SREF/ECMWF WHICH GENERALLY PERFORM BETTER IN
THESE SITUATIONS INVOLVING A RETREATING DAMMING HIGH WITH SOME
CONFLUENCE ALOFT OVER THE CANADIAN MARITIMES TO SUPPORT IT.
AS A RESULT...WENT WITH A BLEND OF COOLER MET GUIDANCE AND NAM
2-METER TEMPERATURES FOR HIGHS...BUT NOT AS COLD AS HRRR 2-METER
TEMPERATURES. EXPECT HIGHS IN THE UPPER 30S ACROSS NORTHERN
INTERIOR ZONES TO LOW-MID 40S ACROSS LONG ISLAND AND THE NYC METRO.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
FOR TIMING THIS SYSTEM BLENDED THE NAM/ECMWF/CMC-GLOBAL/SREF.
EXPECT PRECIPITATION TO COME TO AN END BY MIDNIGHT ACROSS WESTERN
ZONES...AND A COUPLE OF HOURS AFTER MIDNIGHT ACROSS EASTERN ZONES.
MAIN STORY TONIGHT AND SATURDAY WILL BE STRONG TO POTENTIALLY
DAMAGING GUSTY WINDS. WITH SREF SUPPORTING STRONGER GFS LOW
LEVEL/BOUNDARY LAYER WINDS BEHIND THE COLD FRONT...HAVE GONE AHEAD
AND HOISTED A HIGH WIND WATCH FROM 3Z TONIGHT-23Z SATURDAY FOR NYC
AND LONG ISLAND AND A WIND ADVISORY FOR THE REMAINDER OF THE CWA.
THIS IS BASED ON 950 HPA WINDS FORECAST TO AROUND 50 KT AND 900
WINDS FORECAST UP TO 60 KT WITH AN EXPECTED DRY ADIABATIC LAPSE
RATE UP THROUGH AT LEAST 800 HPA BY SATURDAY...WITH THE STRONGEST
WINDS IN THE LOW LEVELS FORECAST OVER NYC/LONG ISLAND. EVEN IN THE
ADVISORY AREA THERE IS THE POTENTIAL FOR SOME DOWNED TREES...BUT
THIS SHOULD BE EVEN MORE NUMEROUS IN THE HIGH WIND WATCH AREA...IF
THESE STRONGER WINDS DO MATERIALIZE.
COULD SEE SOME LAKE EFFECT SNOW/RAIN SHOWERS ACROSS FAR W ORANGE
COUNTY...SATURDAY...SO HAVE SLIGHT CHANCE POPS THERE. WHILE A
SHOWER/SPRINKLE CANNOT BE COMPLETELY RULED OUT ELSEWHERE WITH THE
PASSING OF THE 500 HPA TROUGH AXIS...NOT CONFIDENT ENOUGH TO
REFLECT IN FORECAST.
FOR LOWS TONIGHT BLENDED MAV/MET GUIDANCE WITH NAM 2-METER
TEMPERATURES...AND FOR HIGHS SATURDAY BLENDED MAV/MET GUIDANCE
WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM 800 HPA.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
LOW PRES NEAR NEW BRUNSWICK DEPARTS SATURDAY NIGHT AS HIGH PRES OVER
THE MIDWEST CONTINUES TO BUILD EAST. THE PRESSURE GRADIENT WILL
RELAX SATURDAY NIGHT...ALLOWING NW WINDS TO DIMINISH THROUGH THE
NIGHT. CAA WILL RESULT IN LOWS DROPPING INTO THE LOW TO MID 20S
THROUGHOUT THE CWA. HIGH PRES MOVES EAST ON SUNDAY...THEN WILL BE
JUST SOUTH OF THE REGION SUNDAY NIGHT. HIGH TEMPS WILL BE RIGHT
AROUND NORMAL ON SUNDAY...TOPPING OFF IN THE MID 40S.
OPTIMAL RADIATIONAL COOLING CONDITIONS SET UP SUNDAY NIGHT WITH
MAINLY CLEAR SKIES AND LIGHT WINDS...AND LOWS WILL DROP INTO THE
LOWER 30S IN/AROUND NYC...BUT WILL BE IN THE LOW TO MID 20S
ELSEWHERE.
HIGH PRES MOVES EAST ON MONDAY...AND RETURN FLOW SETS UP WITH A
STRONG S-SW FLOW. WAA WILL PUSH TEMPS WELL ABOVE NORMAL WITH HIGHS
IN THE LOW TO MID 50S OVER WESTERN AREAS AND IN THE MID TO UPPER 40S
OVER EASTERN AREAS. LOW PRES WILL PASS NORTH OF THE AREA LATE
MONDAY...BUT IMPACTS SHOULD BE MINIMAL AND WILL NOT MENTION PRECIP.
HIGH PRES BUILDS THROUGH THE REGION ON TUESDAY...KEEPING WARM AND
DRY CONDITIONS IN THE FORECAST.
MODELS CONTINUE TO BRING A POTENTIALLY SIGNIFICANT SYSTEM INTO THE
REGION FOR THE MIDDLE OF THE WEEK...ALTHOUGH THERE ARE TIMING AND
STRENGTH DIFFERENCES AMONG THE GUIDANCE. WILL CARRY SLIGHT CHANCE
POPS TUESDAY NIGHT AND HIGH CHANCE POPS WEDNESDAY THROUGH THURSDAY
AS THE SYSTEM WORKS ITS WAY THROUGH THE REGION. TEMPS COULD BE COLD
ENOUGH AT NIGHT TO SUPPORT SNOW OR A RAIN/SNOW MIX ACROSS NORTHERN
ZONES WHILE PRECIP WILL GENERALLY BE RAIN ACROSS SOUTHERN ZONES.
DURING THE DAY...PRECIP SHOULD BE ALL RAIN...THOUGH THIS COULD
CHANGE AS MODELS GET A BETTER HANDLE ON THE EVOLUTION OF THE SYSTEM.
HIGHS WEDNESDAY AND THURSDAY WILL TOP OFF IN THE MID TO UPPER 40S
AND LOWS AT NIGHT WILL DROP INTO THE LOW TO MID 30S.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
FR AS A WARM FRONT APPROACHES FROM THE S THIS MORNING. LOW PRESSURE
DEVELOPS ALONG THE FRONT THIS AFTERNOON. A COLD FRONT WILL THEN
SWEEP ACROSS THE AREA LATE THIS EVENING.
PRECIP OVER THE AREA AS OF 09Z WITH KSWF/KHPN/KBDR/KGON EXPERIENCING
SN OR MIXED. HEAVIEST PRECIP LIFTS NE BY 11Z...BECOMING MORE SHOWERY
WITH A CHANGEOVER TO RAIN AFTER SUNRISE.
IFR TO LOW IFR EXPECTED FOR MOST OF THE DAY WITH OCNL -SHRA. THERE
MAY BE A RELATIVE LULL IN PRECIP WITH DZ PREDOMINATING AFTER MID
MORNING. SHOWERS RETURN AHEAD OF THE COLD FRONT LATER IN THE EVENING
ON.
VFR RETURNS OVERNIGHT BEHIND THE FRONT WITH VERY STRONG GUSTY
WESTERLY WINDS.
...NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP://WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: CEILINGS MAY TAKE LONGER TO LOWER THIS MORNING
THAN CURRENTLY FORECAST. LOW CONFIDENCE IN WIND DIRECTION LATER THIS
AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
KJFK FCSTER COMMENTS: CEILINGS MAY TAKE LONGER TO LOWER THIS MORNING
THAN CURRENTLY FORECAST. LOW CONFIDENCE IN WIND DIRECTION LATER THIS
AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
KLGA FCSTER COMMENTS: CEILINGS MAY TAKE LONGER TO LOWER THIS MORNING
THAN CURRENTLY FORECAST. LOW CONFIDENCE IN WIND DIRECTION LATER THIS
AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
KTEB FCSTER COMMENTS: LOW CONFIDENCE IN WIND DIRECTION LATER THIS
AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
KHPN FCSTER COMMENTS: LOW CONFIDENCE IN WIND DIRECTION LATER THIS
AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
KISP FCSTER COMMENTS: LOW CONFIDENCE IN WIND DIRECTION LATER THIS
AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
OUTLOOK FOR 06Z SAT THROUGH TUE...
.FRI NGT-SAT...VFR. STRONG/GUSTY W-NW FLOW. 40-45 KT POSSIBLE
EARLY...THEN GRADUALLY DIMINISHING.
.SUN-TUE...VFR.
&&
.MARINE...
WITH SCA ALREADY UP ON ALL WATERS...DID NOT WANT TO TAKE
DOWN...THOUGH GUSTS ON EASTERLY FLOW OF 10-20 KT MIGHT ONLY
OCCASIONALLY REACH SMALL CRAFT LEVELS TODAY...OVER THE OCEAN ZONES
THOUGH...SCA WARRANTED WITH SEAS ALREADY AT SCA LEVELS.
HAVE HOISTED A STORM WATCH FOR ALL WATERS TONIGHT AND SATURDAY.
THE BEST CHANCE FOR GUSTS TO STORM FORCE ON STRONG WEST WINDS IS
ACROSS SOUTHERN WATERS...THOUGH IF CURRENT FORECAST WIND DIRECTION
HOLDS...THEN CHANNELING EFFECTS IN THE SOUND COULD PROVIDE THE
EXTRA BOOST THERE.
THE TIMING FOR THE STRONGEST WIND GUSTS WILL BE LATE TONIGHT WHEN
THE STRONGEST WINDS PASS AT 900 HPA (AROUND 60 KT)...AND AGAIN
FROM LATE SATURDAY MORNING INTO SATURDAY AFTERNOON...WITH THE
POTENTIAL TO MIX DOWN 50-55 KT WINDS AROUND 800 HPA. THESE WINDS
SHOULD BUILD SEAS ON THE OCEAN TO 6 TO 13 FT AND ON THE SOUND TO
4-8 FT BY SATURDAY MORNING.
GALE FORCE WINDS WILL DIMINISH TO SMALL CRAFT ADVISORY LEVELS ON THE
WATERS FROM WEST TO EAST SATURDAY NIGHT...THEN CONDITIONS GRADUALLY
SUBSIDE TO SUB-ADVISORY LEVELS THROUGH SUNDAY AFTERNOON.
HIGH PRES BUILDS THROUGH THE WATERS FOR THE START OF THE NEW WEEK.
WINDS/SEAS SHOULD REMAIN BELOW SCA LEVELS...THOUGH SEAS MAY BRIEFLY
BUILD TO 3-5 FT ON THE EASTERN OCEAN WATERS MONDAY EVENING AS WEAK
LOW PRES PASSES EAST OF THE WATERS.
&&
.HYDROLOGY...
A STORM TOTAL LIQUID EQUIVALENT RAINFALL OF 1/2 TO 3/4 INCH IS
FORECAST THROUGH THIS EVENING. OTHERWISE...NO SIGNIFICANT PRECIP
IS EXPECTED UNTIL THE MIDDLE OF NEXT WEEK.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WIND ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST SATURDAY FOR
CTZ005>012.
NY...HIGH WIND WATCH FROM THIS EVENING THROUGH SATURDAY AFTERNOON
FOR NYZ072>075-078>081-176>179.
WIND ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST SATURDAY FOR
NYZ067>071.
NJ... WIND ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST SATURDAY FOR
NJZ002-004-006-103>108.
MARINE...STORM WATCH FROM THIS EVENING THROUGH SATURDAY AFTERNOON FOR
ANZ330-335-338-340-345-350-353-355.
SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ330-
335-338-340-345-350-353-355.
&&
$$
SYNOPSIS...MALOIT/MPS
NEAR TERM...MALOIT
SHORT TERM...MALOIT
LONG TERM...MPS
AVIATION...MAS
MARINE...MALOIT/MPS
HYDROLOGY...MALOIT/MPS
AREA FORECAST DISCUSSION
NWS TAUNTON MA
1248 AM EST FRI FEB 24 2012
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL BRING A WINTRY MIX AND HAZARDOUS
CONDITIONS DURING THE MORNING COMMUTE...GRADUALLY CHANGING OVER
TO RAIN TOWARDS THE MIDDAY INTO AFTERNOON HOURS. GUSTY WINDS ARE
LIKELY FRIDAY NIGHT AND SATURDAY AS THIS STORM EXITS. HIGH
PRESSURE KEEPS CONDITIONS DRY THROUGH MUCH OF THE EARLY WEEK. A
COLD FRONT SWINGS THROUGH NEW ENGLAND MONDAY NIGHT.
&&
.NEAR TERM /THROUGH TODAY/...
10 PM UPDATE...
THE CALM BEFORE THE STORM. HAVE UPDATED TEMPERATURE AND DEWPOINT
GRIDS ACCORDINGLY TO REFLECT THE LATEST FORECAST TRENDS. FOR THE
MOST PART EVERYTHING REMAINS ON TRACK WITHIN THE NEAR TERM.
WATCHING AN AREA OF CLEARING PER LATEST SATELLITE TRENDS WHICH
SHOULD ALLOW FOR A BRIEF PERIOD OF RADIATIONAL COOLING RESULTING
IN TEMPS TO FALL BELOW FRZG. THIS IS PRESENTLY THE CASE ACROSS
THE CT VALLEY RGN.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM SATURDAY/...
10 PM UPDATE...
LOOKING AT 18Z AND LATEST 0Z GUIDANCE ATTESTS TO AN AREA OF
DEFINITIVE FRONTOGENETICAL BANDING /AND STRONG VIGOROUS LIFT THRU
THE DENDRITIC GROWTH ZONE REGION/ ALONG AND SOUTH OF THE MASS
PIKE BEGINNING AROUND 4-5 AM AND CONTINUING ON THROUGH THE MORNING
COMMUTE INTO THE MID-MORNING HRS. CHALLENGES TO OVERCOME CONCERN
THE AMOUNT OF PRECIPITATION EXPECTED COUPLED WITH SFC TEMPS AND
BOUNDARY LYR PROFILE UP TO H7. THE LATEST RUNS FROM THE HRRR AND
0Z NAM /INCLUDING THE 12Z RUNS OF THE NMM- AND ARW- CORE WRF
SOLNS/ HAVE PROGRESSIVELY SHOWN THAT ALTHO INITIALLY PRECIPITATION
MAY START OUT IN THE FORM OF RAIN...THE HEAVY NATURE OF THE PRECIP
SHOULD COOL THE LOWER ATMOS COLUMN DOWN TO ITS RESPECTIVE WET-BULB
TEMP /LIKELY AT OR BELOW FRZG/ RESULTING IN THE RAIN TO TRANSITION
OVER TO SNOW. ANTICIPATING MOST LOCALES WILL LIKELY HOVER AROUND
THE FRZG MARK.
AS THE AREA OF LOW PRES BECOMES MORE DYNAMIC ACROSS THE ERN GRT
LKS RGN...MDL SOUNDINGS ARE HIGHLIGHTING A PRONOUNCED WARMING
AROUND H8 WITH INCREASED S/SWLY FLOW AT THE LOW-MID LVLS WHICH
WILL LIKELY RESULT IN SNOW TO TRANSITION TO SLEET. SPATIAL AND
TEMPORAL SPECIFICS ARE DIFFICULT TO PIN DOWN...BUT ONE THING IS
FOR CERTAIN AND THAT SIMPLY IS THE FACT THAT IT WILL BE A MESSY
MORNING COMMUTE FOR LOCALES ALONG AND S OF THE MASS PIKE WITH A
WINTRY MIX RESULTING IN HAZARDOUS DRIVING CONDITIONS AND REDUCED
VISIBILITIES. IMPORTANT TO NOTE IS THE LIKELY IMPACTS TO METRO
AREAS SUCH AS HARTFORD...PROVIDENCE...AND SOUTH BOSTON.
WILL CONTINUE WITH THE CURRENT WINTER WX ADVISORIES...AND HAVE
ISSUED A SPECIAL WEATHER STATEMENT FOR ALL OTHER AREAS ADVISING OF
ISSUES ANTICIPATED DURING THE MORNING COMMUTE. AM WATCHING
CLOSELY THE LATEST 0Z MDL FCSTS FOR FURTHER GUIDANCE. WILL UPDATE
ACCORDINGLY.
AS FOR SNOW TOTALS...AM EXPECTING BANDING THRU THE S TIER OF NEW
ENGLAND AS STATED PREVIOUSLY ALONG AND S OF THE MASS PIKE. WITH
THE INFLUENCE OF WARMER AIR ALOFT...WE MAY NOT SEE A PROLONGED
PERIOD OF SNOW...AND A TRANSITION OVER TO SLEET. LOOKING AT ACCUMS
AROUND 1-2 INCHES PRESENTLY. WILL UPDATE ACCORDINGLY WITH THE
LATEST FCST GUIDANCE. AS KNOWN THERE ARE DIFFERENCES IN ACCUM
BETWEEN SNOW AND SLEET AS SNOW HAS A FLUFF FACTOR. ELY ONSHORE
FLOW INCREASING WITH THE DEEPENING SYS WILL KEEP MUCH OF THE PRECIP
ALONG THE SHORELINES AS MAINLY RAIN /ALTHO AN INITIAL BURST OF
SNOW CANT BE RULED OUT FOR THE WRN CAPE/.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
HIGHLIGHTS...
* SEASONABLE TEMPERATURES EXPECTED THIS WEEKEND
* COLD FRONT MOVES THROUGH MONDAY NIGHT
* STORM MOVES THROUGH MIDDLE OF NEXT WEEK
MODEL DISCUSSION...23/12Z MODELS ARE IN GOOD AGREEMENT THROUGH EARLY
NEXT WEEK. AFTER THAT THERE ARE SOME DIFFERENCES IN HOW A LOW
PRESSURE MOVES THROUGH THE REGION MID-WEEK. THE GFS BRINGS THE LOW
PRESSURE INSIDE OVER NEW YORK AND NORTHERN NEW ENGLAND. THIS IS A
WARMER SCENARIO WHICH WOULD KEEP MOST OF THE PRECIP LIQUID. THE
ECMWF TAKES A MORE COASTAL TRACK WHICH COULD BRING IN ENOUGH COLD
AIR FOR SOME WINTRY PRECIPITATION.
FRIDAY NIGHT...LOW PRESSURE OVER THE AREA WILL MOVE INTO THE
MARITIMES. AS THE LOW DEPARTS THE AREA...ANY LINGERING PRECIP IN THE
AREA WILL DIMINISH AND GUSTY WINDS WILL DEVELOP AS THE PRESSURE
GRADIENT TIGHTENS.
SATURDAY AND SUNDAY...HIGH PRESSURE BUILDS INTO THE REGION BRINGING
SEASONABLY COOL...DRY WEATHER TO SOUTHERN NEW ENGLAND.
MONDAY...LOW PRESSURE MOVES ACROSS QUEBEC BRINGING A COLD FRONT
THROUGH THE REGION MONDAY NIGHT. AT THIS POINT IT LOOKS LIKE IT
WILL BE A DRY FRONTAL PASSAGE.
TUESDAY THROUGH THURSDAY...LOW PRESSURE APPROACHES THE AREA LATE
TUESDAY INTO WEDNESDAY. AS STATED ABOVE IN THE MODEL DISCUSSION
SECTION...THERE ARE DISCREPANCIES REGARDING THE PATH OF THE LOW.
THE EVENTUAL PATH WILL BE THE MAIN FACTOR IN DETERMINING PTYPE FOR
THIS STORM. THERE IS A POSSIBILITY OF A PERIOD OF WINTRY
PRECIPITATION DURING THIS TIME FRAME.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT
MODERATE...30 PERCENT TO 60 PERCENT
HIGH...GREATER THAN 60 PERCENT
REMAINDER OF TONIGHT...
HIGH CONFIDENCE VFR INTO 9-10Z. THEREAFTER SHOULD SEE CIGS AND
VSBYS LOWER TO IFR WITH THE ONSET OF PRECIPITATION DURING THE
EARLY MORNING HRS WITH SN LENDING TO 1-2 VSBYS AND CIGS FALLING
IFR W TO E ACROSS THE TERMINALS. TERMINALS IMPACTED BY RA SHOULD
SEE MVFR VSBYS.
FRIDAY...
HIGH CONFIDENCE IFR-LIFR...ESPECIALLY FOR TERMINALS ALONG AND S OF
THE MASS PIKE WHERE HEAVY BANDING OF PRECIP IS EXPECTED DURING THE
MORNING PD ALONG WITH IFR-LIFR CIGS. TERMINALS IMPACTED BY SN
SHOULD SEE VSBYS AROUND 1 SM WHERE A WINTRY MIX WILL YIELD 2 SM
VSBYS. AREAS WITH RA...LIKELY ALONG THE SE TERMINALS...WILL SEE A
MIX OF IFR-MVFR VSBYS. ELY WINDS STRONGEST ALONG THE SHORES.
CONDITIONS MAY SEE A SLIGHT IMPROVEMENT TOWARDS THE LATE PORTION
OF THE DAY AS PRECIP MOVES OUT OF THE RGN.
FRIDAY NIGHT...
MODERATE CONFIDENCE IFR LIFTING VFR. WILL SEE PRECIP THE EARLY
PORTION OF THE TAF PD AS A MIX OF RA/SN LENDING TO REDUCED VSBYS.
WILL LIKELY BE IFR CIGS HANGING AROUND. BY MIDNIGHT DRIER AIR
SHOULD ALLOW FOR CONDITIONS TO STEADILY IMPROVE INTO MORNING.
EXPECT ELY FLOW TO REVERT OUT OF THE SW AND INCREASE.
KBOS TERMINAL...
DETERIORATING CONDITIONS SHORTLY BEFORE MORNING WITH THE INITIAL
ONSET OF SNOW. ANTICIPATING WITH ELY ONSHORE FLOW THAT SN WILL BE
BRIEF AND CHANGE OVER TO RA. NEVERTHELESS SHOULD STILL SEE IFR-
LIFR CIGS IMPACT THE TERMINAL A GOOD PORTION OF THE DAY...STEADILY
IMPROVING OVRNGT AS ELY WINDS SHIFT AND INCREASE OUT OF THE SW.
OUTLOOK...SATURDAY THROUGH TUESDAY...
SATURDAY THROUGH TUESDAY...MODERATE TO HIGH CONFIDENCE. VFR. WINDS
GUST UP TO 30 KNOTS SATURDAY...PARTICULARLY ON THE COAST.
&&
.MARINE...
TONIGHT...
WINDS WILL DIMINISH ACROSS THE WATERS AS HIGH PRES BUILDS INTO THE
RGN. EXPECT WAVES TO STILL REMAIN AROUND 5 FEET FOR THE OPEN
WATERS...SMALL CRAFT ADVISORIES ARE CONTINUED. WILL SEE
SEAS BEGIN TO BUILD AFTER MIDNIGHT AND INTO FRIDAY IN RESPONSE TO
A BUILDING SYSTEM THRU THE GREAT LAKES...ELY FLOW TO INCREASE
ALONG WITH WAVE HEIGHTS.
FRIDAY...
STRONG STORM SYSTEM POISED TO LIFT THRU NEW ENGLAND. ELY FLOW WILL
CONTINUE ACROSS THE AREA AND WILL LIKELY TO SEE WINDS GUSTING IN
EXCESS OF 25 KTS WITH BUILDING SEAS UP TO 10 FT. THERE IS A LOW
PROBABILITY OF GALE FORCE WIND GUSTS LATE IN THE PD.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
FRIDAY NIGHT AND SATURDAY...WINDS AND SEAS INCREASE AS LOW PRESSURE
MOVES OVER THE WATERS. A GALE WATCH HAS BEEN ISSUED FOR THIS TIME
PERIOD. EASTERLY WINDS TO START WILL SWITCH AROUND TO THE WEST
EARLY SATURDAY.
SATURDAY NIGHT AND SUNDAY...WINDS AND SEAS DIMINISH AS HIGH PRESSURE
STARTS TO BUILD OVER THE WATERS. SMALL CRAFT ADVISORIES WILL LIKELY
BE NEEDED FOR AT LEAST A PORTION OF THIS TIME.
SUNDAY NIGHT...WINDS BELOW 25 KTS. SEAS WILL BE 5-6 FEET ON THE
OUTER WATERS...DIMINISHING BELOW 5 FEET AFTER MIDNIGHT.
MONDAY...WINDS AND SEAS WILL REMAIN BELOW SMALL CRAFT CRITERIA.
MONDAY NIGHT THROUGH TUESDAY...WINDS AND SEAS WILL RISE FOR A BRIEF
PERIOD MONDAY NIGHT AS A COLD FRONT MOVES ACROSS THE WATERS. THEN
WINDS AND SEAS DIMINISH BELOW SMALL CRAFT CRITERIA AND REMAIN THERE
THROUGH TUESDAY.
&&
.CLIMATE...
FEBRUARY OF 2012 IS SHAPING UP TO BE ANOTHER MONTH WITH WELL ABOVE
NORMAL TEMPERATURES IN SOUTHERN NEW ENGLAND. IN FACT...FROM JULY
2011 ONWARD EVERY MONTH HAS AVERAGED ABOVE NORMAL TEMPERATURES AT
ALL 4 MAJOR CLIMATE SITES.
FEBRUARY MONTHLY AVERAGE AND DEPARTURES THROUGH THE 21TH:
BOSTON - 36.3 DEGREES WHICH IS +5.2 ABOVE NORMAL: TIED FOR 5TH
TOP 5 WARMEST FEBRUARIES IN BOSTON SINCE 1872
1) 38.0 DEGREES IN 1925
2) 37.6 DEGREES IN 1984
3) 37.3 DEGREES IN 1976
4) 36.4 DEGREES IN 1954 AND 1981
5) 36.3 DEGREES IN 2002
PROVIDENCE - 35.2 DEGREES WHICH IS +3.9 ABOVE NORMAL
TOP 5 WARMEST FEBRUARIES IN PROVIDENCE SINCE 1905: NOT IN TOP 5
1) 37.4 DEGREES IN 1981
2) 37.1 DEGREES IN 1984
3) 37.0 DEGREES IN 1998
4) 36.5 DEGREES IN 1997
5) 36.3 DEGREES IN 1949
WINDSOR LOCKS - 35.4 DEGREES WHICH IS +6.4 ABOVE NORMAL: 3RD SO FAR
TOP 5 WARMEST FEBRUARIES IN WINDSOR LOCKS SINCE 1905
1) 36.2 DEGREES IN 1954 AND 1998
2) 35.6 DEGREES IN 1925
3) 35.3 DEGREES IN 1981
4) 34.8 DEGREES IN 1976
5) 34.7 DEGREES IN 1997
WORCESTER - 32.2 DEGREES WHICH IS +5.9 ABOVE NORMAL
TOP 5 WARMEST FEBRUARIES IN WORCESTER SINCE 1892: NOT IN TOP 5
1) 34.0 DEGREES IN 1984
2) 33.4 DEGREES IN 1925
3) 32.9 DEGREES IN 1998
4) 32.8 DEGREES IN 1981
5) 32.4 DEGREES IN 1954
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
MAZ002>004-008>010-026.
NH...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR NHZ011-
015.
RI...NONE.
MARINE...GALE WATCH FROM THIS EVENING THROUGH SATURDAY AFTERNOON FOR
ANZ230>237-250-251-254>256.
SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR ANZ235-
237-250-254>256.
&&
$$
SYNOPSIS...RLG/DUNTEN
NEAR TERM...SIPPRELL
SHORT TERM...SIPPRELL
LONG TERM...RLG
AVIATION...RLG/SIPPRELL
MARINE...RLG/DUNTEN
CLIMATE...WFO BOX
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
230 AM CST FRI FEB 24 2012
.DISCUSSION...
901 PM CST
NO CHANGES TO GOING ADVISORY HEADLINES THIS EVENING. HOWEVER...
FORECAST REMAINS QUITE COMPLEX WITH RESPECT TO SNOW AMOUNTS AND
PRECIP TYPES THROUGH THE EARLY OVERNIGHT HOURS.
EVENING VAPOR IMAGERY SHOWS STRONG SHORT WAVE TROUGH DIGGING
EAST-SOUTHEAST ACROSS IA/MO. MAIN SFC LOW WAS OVER SOUTHERN INDIANA
WITH TROUGH TRAILING BACK THROUGH WESTERN IL/SOUTHERN IA. INITIAL
PUSH OF WARM ADVECTION RAIN/SNOW HAD GENERALLY LIFTED TO/NORTH OF
THE WI BORDER DURING THE EVENING HOURS...WHILE FARTHER TO THE WEST
REGIONAL RADAR MOSAIC DEPICTED EXTENSION OF BROAD DEVELOPING
DEFORMATION BAND FROM SOUTHWEST IA INTO SOUTHERN WI. EVIDENCE OF
FRONTOGENETICALLY FORCED ENHANCED PRECIPITATION WAS NOTED ACROSS FAR
EASTERN IA...JUST NORTH OF THE QUAD CITIES.
MUCH OF THE CWA HAS SEEN A LULL IN MORE ORGANIZED MEASURABLE PRECIP
DURING THE EVENING HOURS. 22-23Z RUNS OF THE HRRR SEEM TO HAVE A
VERY GOOD HANDLE ON TRENDS ACROSS THE REGION THROUGH MID-EVENING...
AND WOULD SUGGEST DEFORMATION PRECIP AXIS WILL GRADUALLY TRANSLATE
EAST ACROSS THE AREA DURING THE OVERNIGHT/FRIDAY MORNING HOURS.
WHILE THE CURRENT BAND NEAR DVN IS IMPRESSIVE LOOKING...HIGH RES
SHORT TERM MODEL TRENDS WOULD SUGGEST THIS WOULD WEAKEN AND BECOME
SOMEWHAT LESS FOCUS AS IT TRANSLATES EASTWARD...THOUGH ENTIRE
DEFORMATION PRECIP AREA WILL LIKELY BECOME A BIT BETTER ORGANIZED.
WITH LESS PRECIPITATION...ESPECIALLY IN THE FORM OF SNOW ACROSS THE
AREA DURING THE EARLY/MID EVENING HORUS...HAVE ADJUSTED SNOWFALL
AMOUNTS DOWN SOMEWHAT FROM PREVIOUS FORECAST...GENERALLY 2-6 INCHES
WITH THE HEAVIER AMOUNTS GENERALLY ALONG/NORTH OF INTERSTATE 88 IN
NORTHERN/NORTHEAST IL. SOME HIGHER AMOUNTS STILL NOT OUT OF THE
QUESTION GIVEN POTENTIAL FOR MESOSCALE BANDING...AND POTENTIAL FOR
CONVECTION...BUT OVERALL CONFIDENCE REMAINS FAIRLY LOW EVEN AT THIS
RELATIVELY CLOSE-IN TIME.
SOUTH OF ROUGHLY A DVN-ORD LINE HOWEVER...THE HRRR WOULD INDICATE
MORE CONVECTIVE SHOWERY TYPE PRECIP...WHICH HAS BEEN OCCURRING AS A
MIX OF RAIN/SNOW/GRAUPEL PER REPORTS IN UPSTREAM AREAS. THIS APPEARS
QUITE REASONABLE AS AREA OF STEEP MID-LEVEL LAPSE RATES...IN EXCESS
OF 7 DEG/KM PER RUC/SPC MESOANALYSIS...WILL CONTINUE TO SPREAD
ACROSS THE SOUTHERN PARTS OF THE CWFA OVERNIGHT. HAVE CONTINUED TO
INDICATE SHOWERS/CHANCE THUNDER CHANGING TO SNOW DURING THE
OVERNIGHT HOURS...WITH SNOWFALL AMOUNTS QUICKLY DECREASING THROUGH
THE I-80 CORRIDOR SOUTHWARD.
RATZER
//PREV DISCUSSION...
322 PM CST
THE WINTER SYSTEM IS STILL OFFERING PLENTY OF COMPLEXITIES INTO
TONIGHT AND FRIDAY MORNING...WITH TRANSITION TIME TO SNOW AND
TOTAL DURATION OF SNOW REMAINING THE MAIN CHALLENGES WITH THE
FORECAST.
WARM AIR ADVECTION DRIVEN PRECIPITATION...AT TIMES LARGE
SNOWFLAKES UNDER THE HIGHEST REFLECTIVITY...HAS LIFTED GRADUALLY
NORTH ACROSS THE AREA THROUGH THE AFTERNOON. THIS HAS BEEN ALONG A
TIGHTENING MID-LEVEL THERMAL GRADIENT WHICH SHOULD NOT MOVE MUCH
FURTHER NORTH AT ALL INTO TONIGHT. THIS OFFERS A LIKELY
INDICATION ON WHERE THE BANDED POTENTIAL AND HEAVIER PRECIPITATION
WILL BE TONIGHT AS THE UPPER WAVE APPROACHES. AT THE SURFACE
...LOW-LEVEL TEMPERATURES AND DEW POINTS HAVE DROPPED THIS
AFTERNOON UNDER PRECIP AND GRADUALLY BACKING WINDS. TEMPERATURES
SHOULD BASICALLY NOT CLIMB ANYMORE WITH THE MAIN WARM FRONT WELL
TO THE SOUTH JUST NORTH OF THE OHIO RIVER. PER VISIBLE
SATELLITE...MOISTURE AND INSTABILITY ARE EVIDENT LIFTING NORTH OF
THIS FRONT ACROSS CENTRAL IL AND IN...EVEN WITH A POSSIBLE
EMBEDDED DISTURBANCE. SCATTERED SHOWERS AND EVEN ELEVATED STORMS
ARE EXPECTED TO DEVELOP IN THAT AREA AND POTENTIALLY CLIP THE
SOUTHEAST FORECAST AREA THIS EVE.
THE MAIN UPPER SYSTEM CONTINUES TO ORGANIZE ACROSS THE MISSOURI
RIVER VALLEY IN ASSOCIATION WITH THE DIGGING 170 KT UPPER LEVEL
JET. AS THIS TRANSLATES EAST...LARGE SCALE ASCENT WILL OVERRIDE
THE EXISTING MID-LEVEL BOUNDARY AND LIKELY LEAD TO A RE-
ENHANCEMENT OF PRECIP EARLY THIS EVENING. STRENGTHENING SYSTEM
MOISTURE RETURN ON A LOW-LEVEL JET...ALMOST MORE OF A LOW LEVEL
/900-750MB/ TROWAL...WILL WRAP INTO THE AREA AS WELL. THE LAPSE
RATES WILL STEEPEN ALOFT THROUGH THE DIFFERENTIAL TEMPERATURE
ADVECTION AND SHOULD BE ENOUGH TO SUPPORT HEAVIER PRECIP RATES
AND MAXIMIZING THE INITIAL HIGH LOW LEVEL MIXING RATIOS OF 3 TO 4
G/KG. THERE REMAINS THAT CHANCE FOR THUNDER WITH THE
INSTABILITY...WHICH WOULD LEAD TO TEMPORARY VERY HEAVY PRECIP
RATES.
OVERALL THE INCREASING SUPPORT FOR MORE STEADY AND WIDESPREAD
PRECIP WILL SUPPORT DYNAMIC COOLING. THAT COUPLED WITH THE COOLING
FROM THE DIURNAL TREND AND SLIGHT COOL ADVECTION WILL WARRANT RAIN
CHANGING TO A MORE PREVALENT SNOW FROM WEST TO EAST ACROSS THE
ADVISORY AREA THIS EVENING...MAINLY PRIOR TO 10 PM. ALREADY
THROUGH BRIGHT BANDING AND DUAL-POL PRODUCTS THE MELTING LAYER IS
NOT FAR ALOFT AT ALL ACROSS THE ENTIRE AREA. THE TIMING OF
CHANGEOVER WILL DIRECTLY IMPACT HOW MUCH SNOW...AS SOME OF THE
HEAVIER RATES ARE FAVORED IN THE HOURS IMMEDIATELY AFTER CHANGE
OVER DUE TO MID-LEVEL FGEN AND INSTABILITY. THERE SHOULD BE A
TIGHT GRADIENT IN SNOWFALL THROUGH THIS EVENING...WITH AREAS ALONG
AND SOUTH OF INTERSTATE 80 NOT EXPECTED TO SEE ANY ACCUMULATION
BASICALLY...AND THAT DEMARCATION MAY EVEN BE FURTHER NORTH TOWARDS
THE U.S. HIGHWAY 34. HAVE GUIDED ON QPF CLOSE TO THE 12Z/18Z NAM
AND 09Z SREF...WITH RATIOS ADJUSTED QUITE LOW AND GRADUALLY
INCREASING TOWARDS 15 TO 1 TOWARDS ROCKFORD WHERE DENDRITIC GROWTH
LAYER IS DEEPER.
BY LATE EVENING INTO OVERNIGHT...THE SYSTEM 850 AND 700 MB LOWS
WILL PASS OVER /OR AT THEIR CLOSEST POINT TO/ THE AREA.
DEFORMATION IS INDICATED BY ALL GUIDANCE IN THIS TIME. PRECIP TYPE
WILL TRANSITION TO SNOW OVER ALMOST THE ENTIRE AREA...BUT THE
DEEPEST MOISTURE AND INSTABILITY/NEGATIVE EPV WILL GRADUALLY BE
WANING. THE TREND IN THE EC AND NAM/SREF HAS BEEN SLOWER WITH
REMOVING THE SYSTEM...WITH ALMOST A SECONDARY FLARE UP IN THE
MORNING AS THE POSITIVELY TILTED UPPER TROUGH SHIFTS EAST. SO HAVE
HELD ON TO ACCUMULATING SNOW LONGER...ESPECIALLY ACROSS CHICAGO
AND NORTHWEST IN. EVEN SOME LAKE ENHANCEMENT IS POSSIBLE LATE
TONIGHT INTO FRIDAY MORNING. AMOUNTS AFTER DAYBREAK OF AROUND ONE
INCH ARE EXPECTED IN FAR NORTHEAST IL INTO NORTHWEST IN...WHERE
SLIGHTLY HIGHER AMOUNTS MAY OCCUR.
STORM TOTAL SNOWFALL ACCUMULATIONS THROUGH FRIDAY MORNING ARE 4 TO
7 INCHES ACROSS MUCH OF THE ADVISORY AREA...OUTSIDE OF THE
SOUTHERN COUNTIES /I-80 CORRIDOR/ WHICH HAVE QUITE A TIGHT
GRADIENT IN TOTAL SNOWFALL FORECAST. ANY LOCATIONS THAT SEE SOME
OF THE PERSISTENT HEAVIER RATES...OR THUNDER SNOW...WILL END UP
HAVING HIGHER AMOUNTS ESPECIALLY DURING THIS EVENING. A SHORT FUSE
WINTER STORM WARNING MAY BE NEEDED FOR A WHILE IF THE BANDING IS A
PARTICULARLY STRONG AND STAGNANT SIGNATURE. WITH THE TIMING OF THE
HEAVIEST SNOW BEING AT THE TAIL END AND AFTER THE EVENING RUSH
HOUR...AND RATES GRADUALLY DIMINISHING DURING THE DAYBREAK
TIME...PUBLIC IMPACTS WOULD SEEM TO BE SLIGHTLY LOWER. SO CONTINUE
TO GO WITH THE ADVISORY AT THIS TIME.
MTF
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY...
320 PM...LIGHT SNOW OR SNOW SHOWERS LIKELY TO STILL BE ONGOING
FRIDAY EVENING AS THE LOW LIFTS NORTHEAST AND COLDER AIR ADVECTS
ACROSS THE AREA. EXPECT SNOW SHOWERS TO DECREASE IN COVERAGE AND
INTENSITY THROUGH THE NIGHT BUT STILL THE POTENTIAL FOR SOME
ADDITIONAL...THOUGH MINOR ACCUMULATION FRIDAY EVENING ESPECIALLY
ACROSS NORTHEAST IL INTO NORTHWEST INDIANA. WITH AT LEAST SOME
PARTIAL CLEARING IN ADDITION TO THE COLD AIR ADVECTION...EXPECT
TEMPS TO DIP INTO THE TEENS ACROSS NORTHWEST IL AND GIVEN THE
EXPECTED SNOWFALL TONIGHT...TEMPS COULD DROP EVEN FURTHER WITH
THE FRESH SNOWPACK.
THE WEEKEND IS LOOKING FAIRLY QUIET AS A LARGE RIDGE OF HIGH
PRESSURE BUILDS ACROSS THE REGION ON SATURDAY...SHIFTING EAST
SATURDAY NIGHT INTO SUNDAY. DESPITE SUNSHINE...AIRMASS REMAINS
FAIRLY COLD SATURDAY COMBINED WITH THE SNOWPACK...HIGHS MAY ONLY
REACH LOW/MID 30S. WITH LIGHT WINDS AND CLEAR SKIES...SHOULD SEE
A QUICK DROP IN TEMPS SATURDAY EVENING BUT WITH STRONG WARMING
ALOFT OVERNIGHT...TEMPS LIKELY TO BECOME STEADY OR EVEN BEGIN
RISING A FEW DEGREES OVERNIGHT INTO SUNDAY MORNING.
ANOTHER STORM SYSTEM THEN MOVES EAST ACROSS THE UPPER MIDWEST AND
NORTHERN LAKES SUNDAY AND SUNDAY NIGHT AND IT APPEARS THE BULK OF
THE PRECIP WITH THIS SYSTEM WILL REMAIN NORTH OF THE CWA BUT AS A
WEAK COLD FRONT MOVES ACROSS THE AREA SUNDAY NIGHT...THERE COULD BE
A PASSING SNOW OR RAIN SHOWER SUNDAY NIGHT AND HAVE MAINTAINED LOW
CHANCE POPS DURING THIS TIME. WITH STRONG WARMING CONTINUING SUNDAY
AHEAD OF THIS STORM SYSTEM...DEWPOINTS RECOVER INTO THE LOWER 30S
AND DESPITE THE SNOWPACK...TEMPS HAVE THE POTENTIAL TO WARM INTO
THE 40S...PERHAPS EVEN WARMER SOUTH OF WHEREVER THE MORE
SIGNIFICANT SNOW PACK ENDS UP FALLING OVER THE NEXT DAY.
THEN COMES NEXT WEEK AND THE POTENTIAL FOR ANOTHER SIMILAR STORM
TO THE ONE TO AFFECT THE AREA TONIGHT. MODELS DIFFER ON THE OVERALL
TIMING/PROGRESSION OF THIS STORM SYSTEM WITH THE ECMWF MUCH DEEPER
AND SLOWER WITH THE LOW NOT MOVING EAST ACROSS THE AREA UNTIL
WEDNESDAY AFTERNOON...WHICH IS MUCH SLOWER THAN THE WEAKER/FASTER
GFS. APPEARS LOW LEVELS WILL BE WARM ENOUGH TO SUPPORT ALL RAIN
UNTIL THE LOW MOVES EAST WHEN PRECIP COULD QUICKLY CHANGE TO SNOW
BEFORE ENDING. TOO FAR OUT IN TIME FOR SPECIFICS AND ALSO KEPT
MENTION OF RAIN OR SNOW OVER MUCH OF THE NORTHERN CWA. CMS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 08Z...
* -RAPLSN CHANGING TO -SN AT MDW NEXT 1-2 HRS.
* PERIOD OF MOST INTENSE SNOWFALL EXPECTED 10/11Z UNTIL APPROX
13/14Z THEN DECREASING IN INTENSITY...VSBY TO AROUND 1/2SM
POSSIBLE AT TIMES.
* IFR/LIFR CIGS PERSIST THROUGH MID MORNING THEN IMPROVE AND
BECOME MORE VARIABLE LATE MORNING.
* NE WINDS TURNING NORTH THEN NORTHWEST THROUGH MIDDAY WITH GUSTS
INCREASING INTO THE MID 20S KT.
* ADDITIONAL SCATTERED SNOW SHOWERS POSSIBLE MID/LATE AFTERNOON
WITH IFR VSBY POSSIBLE.
MDB
//DISCUSSION...UPDATED 08Z...
SNOW BECOMING MORE WIDESPREAD IN COVERAGE ACROSS CENTRAL AND
WESTERN SECTIONS OF THE CHI METRO AS A MID LEVEL SPEED MAX ARRIVES
FROM THE SOUTHWEST WITH THE MAIN UPPER TROUGH AXIS PIVOTING
ACROSS THE MISSISSIPPI RIVER. HEAVIEST BAND OF SNOW EXTENDS FROM
NEAR KJVL TO KDVN TO KMPZ AND CONTINUES TO SWING EASTWARD. LATEST
TRENDS SUPPORT A SLIGHTLY SLOWER ARRIVAL WITH IT REACHING THE CHI
METRO TERMINALS TOWARD 10/11Z BUT CLEARING RFD IN THE 12/13Z OR SO
TIME FRAME. TIMING MAY NEED TO BE SLOWED SLIGHTLY. UNTIL
THE...EXPECT VARIABLE VSBY CONDS IN -SN WITH MIXED PRECIP CHANGING
TO SNOW AT MDW IN THE NEXT 1-2 HRS. ONE OTHER CONCERN IS POTENTIAL
FOR A VERY SHORT WINDOW OF LAKE ENHANCEMENT OF THE MAIN BAND
TOWARD DAYBREAK AS AIR ALOFT BECOMES COLD ENOUGH FOR A LAKE
RESPONSE AND WINDS REMAIN JUST EAST OF NORTH. WILL NEED TO KEEP AN
EYE ON THIS AS IT MAY RESULT IN A SHORT PERIOD OF MORE INTENSE
SNOWFALL AND 1/4SM VSBY IN THE CHI METRO BUT THIS LOOKS TO BE A
LOW CHANCE SCENARIO WITH MARGINAL PARAMETERS AND WOULD BE VERY
SHORT LIVED BEFORE WINDS TURN JUST WEST OF NORTH.
MDB
FROM 06Z...
BAND OF MODERATE TO OCCASIONALLY HEAVY SNOW HAS BECOME FAIRLY
WELL SITUATED FROM S WI/FAR N IL WSW INTO SOUTHERN IA. TO THE
SOUTH OF THIS BAND WDLY SCTD RAIN/SNOW/GRAUPEL SHOWERS HAVE BEEN
COMMON WITH SOME DZ/BR IN BETWEEN THE SHOWERS. AS UPPER LOW OVER
IA PIVOTS EASTWARD LOOK FOR BAND OF MOD-HEAVY SNOW TO MIGRATE
SOUTHEASTWARD INTO THE CHGO METRO TERMINALS. PRESENCE OF STEEP MID
LEVEL LAPSE RATES AND FAIRLY STRONG ASCENT CERTAINLY SUGGEST SOME
POTENTIAL FOR SOME HEAVIER ELEMENTS AND POSSIBLY EVEN A RUMBLE OF
THUNDER.
ORGANIZED SYSTEM SNOW SHOULD PULL OUT FRIDAY MORNING WITH CLOUDY
AND BLUSTERY CONDITIONS IN ITS WAKE. FORECAST SOUNDINGS SUGGEST
NOT ONLY STRONG/GUSTY WINDS WITH GUSTS OF 25-30KT PROBABLE.
ALSO...VERY STEEP LOW AND MID LEVEL LAPSE RATES WITH FAIRLY HIGH
BOUNDARY LAYER MOISTURE MEANS IT WILL TAKE RELATIVELY LITTLE TO
KICK OF SOME FRISKY SNOW SHOWERS DURING THE AFTERNOON FRIDAY.
MODELS DO SUGGEST A WEAK WAVE WILL ROTATE SOUTHEAST INTO THE AREA
LATER FRIDAY AFTERNOON AND HAVE KEYED IN ON THAT TIMING FOR A
PROB30 OF SHSN.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 08Z...
* MEDIUM-HIGH CONFIDENCE IN MIXED PRECIP TURNING TO SNOW AT MDW.
* MEDIUM-HIGH CONFIDENCE IN HEAVIEST SNOW OCCURRING 10/11Z UNTIL
APPROX 13/14Z...MEDIUM CONFIDENCE ON VSBY TO AROUND 1/2SM AT TIMES.
* HIGH CONFIDENCE IFR/LIFR CIGS CONTINUING THROUGH MID MORNING
WITH UPWARD TREND INTO EARLY AFTERNOON...MEDIUM CONFIDENCE IN
SPECIFIC TIMING.
* HIGH CONFIDENCE IN WIND TRENDS.
* LOW-MEDIUM CONFIDENCE IN SHSN THREAT THIS AFTERNOON.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 08Z...
SATURDAY...VFR.
SUNDAY...VFR AND WINDY FROM THE SOUTH/SOUTHWEST.
MONDAY...VFR.
TUESDAY...CHANCE FOR RAIN/SNOW...POSSIBLE MVFR.
WEDNESDAY...CHANCE FOR RAIN/SNOW...POSSIBLE MVFR.
MDB
&&
.MARINE...
230 AM CST
LOW PRESSURE MOVING ACROSS THE OHIO VALLEY THIS MORNING WILL LIFT
NORTHEASTWARD ACROSS THE EASTERN GREAT LAKES LATER TODAY AND
TONIGHT. AS THIS OCCURS...THE SURFACE LOW WILL DEEPEN TO NEAR 29.0
INCHES. OVERALL...THIS WILL RESULT IN A GRADUAL SHIFT FROM
NORTHEASTERLY WINDS CURRENTLY TO NORTH THIS MORNING...THEN TO
NORTHWEST THIS AFTERNOON AND TONIGHT. WIND SPEEDS WILL LIKELY REMAIN
IN THE 20 KT TO 30 KT RANGE. HOWEVER...BY THIS EVENING DECENT HEIGHT
RISES OCCURRING BEHIND THE EXITING LOW MAY ALLOW THE WINDS TO
INCREASE A BIT. THERE IS THE POSSIBILITY OF A SHORT PERIOD OF SOME
LOW END GALE FORCE GUSTS THIS EVENING INTO THE OVERNIGHT.
HOWEVER...DUE TO THE SHORT DURATION I AM NOT PLANNING ANY HEADLINES
FOR GALES...I WILL ONLY MENTION AS SOME OCCASIONAL GALE FORCE GUSTS.
SURFACE HIGH PRESSURE WILL BUILD ACROSS LAKE MICHIGAN DURING THE DAY
ON SATURDAY ALLOWING THE WINDS TO EASE FOR A PERIOD. THIS WILL BE
SHORT LIVED...HOWEVER...AS ANOTHER AREA OF LOW PRESSURE TAKES SHAPE
ACROSS THE PLAINS STATES AND MOVES EAST ACROSS THE MID MISSOURI
VALLEY SATURDAY NIGHT AND ACROSS THE UPPER MISSISSIPPI RIVER VALLEY
ON SUNDAY. THIS LOW IS FORECAST TO BE IN A WEAKENING STAGE AS IT
APPROACHES LAKE MICHIGAN. HOWEVER...IN SPITE OF THIS...IT APPEARS
THAT A STRONG PRESSURE GRADIENT WILL SET UP AHEAD OF THIS LOW AS IT
INTERACTS WITH A POTENT SURFACE HIGH ACROSS THE OHIO VALLEY.
THEREFORE...STRONG SOUTHERLY FLOW LOOKS TO SET UP ACROSS LAKE
MICHIGAN LATE ON SUNDAY AND SUNDAY NIGHT AS STRONG PRESSURE FALLS
AHEAD OF THE LOW OVERSPREAD THE UPPER GREAT LAKES. IT STILL APPEARS
THAT GALE FORCE WINDS WILL BE HIGHLY PROBABLE DURING THIS
PERIOD...SO I WILL CONTINUE THE MENTION OF GALES. THE SURFACE LOW
APPEARS THAT IT WILL TRACK JUST NORTH OF LAKE MICHIGAN LATE SUNDAY
NIGHT. THIS TRACK WILL RESULT IN THE ASSOCIATED FRONTAL ZONE PUSHING
ACROSS THE LAKE SOMETIME SUNDAY NIGHT...ALLOWING THE WINDS TO SWITCH
OUT OF THE WEST SOUTHWEST. DUE TO THE FACT THE LOW WILL LIKELY BE
WEAKENING AS IT MOVES EAST OF THE LAKE ON MONDAY...THE POTENTIAL FOR
WESTERLY GALE FORCE WINDS ON MONDAY LOOKS LOW.
YET ANOTHER POTENT LOW PRESSURE SYSTEM LOOKS TO AFFECT THE GREAT
LAKES BY THE MIDDLE OF NEXT WEEK. THIS SYSTEM ALSO HAS THE POTENTIAL
TO PRODUCE WINDS IN EXCESS OF 30 KT.
KJB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ006-ILZ013-ILZ014-ILZ022 UNTIL NOON
FRIDAY.
WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ019-ILZ020 UNTIL 9 AM FRIDAY.
IN...WINTER WEATHER ADVISORY...INZ001-INZ002 UNTIL NOON FRIDAY.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 4 PM FRIDAY.
SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
222 AM CST FRI FEB 24 2012
.DISCUSSION...
901 PM CST
NO CHANGES TO GOING ADVISORY HEADLINES THIS EVENING. HOWEVER...
FORECAST REMAINS QUITE COMPLEX WITH RESPECT TO SNOW AMOUNTS AND
PRECIP TYPES THROUGH THE EARLY OVERNIGHT HOURS.
EVENING VAPOR IMAGERY SHOWS STRONG SHORT WAVE TROUGH DIGGING
EAST-SOUTHEAST ACROSS IA/MO. MAIN SFC LOW WAS OVER SOUTHERN INDIANA
WITH TROUGH TRAILING BACK THROUGH WESTERN IL/SOUTHERN IA. INITIAL
PUSH OF WARM ADVECTION RAIN/SNOW HAD GENERALLY LIFTED TO/NORTH OF
THE WI BORDER DURING THE EVENING HOURS...WHILE FARTHER TO THE WEST
REGIONAL RADAR MOSAIC DEPICTED EXTENSION OF BROAD DEVELOPING
DEFORMATION BAND FROM SOUTHWEST IA INTO SOUTHERN WI. EVIDENCE OF
FRONTOGENETICALLY FORCED ENHANCED PRECIPITATION WAS NOTED ACROSS FAR
EASTERN IA...JUST NORTH OF THE QUAD CITIES.
MUCH OF THE CWA HAS SEEN A LULL IN MORE ORGANIZED MEASURABLE PRECIP
DURING THE EVENING HOURS. 22-23Z RUNS OF THE HRRR SEEM TO HAVE A
VERY GOOD HANDLE ON TRENDS ACROSS THE REGION THROUGH MID-EVENING...
AND WOULD SUGGEST DEFORMATION PRECIP AXIS WILL GRADUALLY TRANSLATE
EAST ACROSS THE AREA DURING THE OVERNIGHT/FRIDAY MORNING HOURS.
WHILE THE CURRENT BAND NEAR DVN IS IMPRESSIVE LOOKING...HIGH RES
SHORT TERM MODEL TRENDS WOULD SUGGEST THIS WOULD WEAKEN AND BECOME
SOMEWHAT LESS FOCUS AS IT TRANSLATES EASTWARD...THOUGH ENTIRE
DEFORMATION PRECIP AREA WILL LIKELY BECOME A BIT BETTER ORGANIZED.
WITH LESS PRECIPITATION...ESPECIALLY IN THE FORM OF SNOW ACROSS THE
AREA DURING THE EARLY/MID EVENING HORUS...HAVE ADJUSTED SNOWFALL
AMOUNTS DOWN SOMEWHAT FROM PREVIOUS FORECAST...GENERALLY 2-6 INCHES
WITH THE HEAVIER AMOUNTS GENERALLY ALONG/NORTH OF INTERSTATE 88 IN
NORTHERN/NORTHEAST IL. SOME HIGHER AMOUNTS STILL NOT OUT OF THE
QUESTION GIVEN POTENTIAL FOR MESOSCALE BANDING...AND POTENTIAL FOR
CONVECTION...BUT OVERALL CONFIDENCE REMAINS FAIRLY LOW EVEN AT THIS
RELATIVELY CLOSE-IN TIME.
SOUTH OF ROUGHLY A DVN-ORD LINE HOWEVER...THE HRRR WOULD INDICATE
MORE CONVECTIVE SHOWERY TYPE PRECIP...WHICH HAS BEEN OCCURRING AS A
MIX OF RAIN/SNOW/GRAUPEL PER REPORTS IN UPSTREAM AREAS. THIS APPEARS
QUITE REASONABLE AS AREA OF STEEP MID-LEVEL LAPSE RATES...IN EXCESS
OF 7 DEG/KM PER RUC/SPC MESOANALYSIS...WILL CONTINUE TO SPREAD
ACROSS THE SOUTHERN PARTS OF THE CWFA OVERNIGHT. HAVE CONTINUED TO
INDICATE SHOWERS/CHANCE THUNDER CHANGING TO SNOW DURING THE
OVERNIGHT HOURS...WITH SNOWFALL AMOUNTS QUICKLY DECREASING THROUGH
THE I-80 CORRIDOR SOUTHWARD.
RATZER
//PREV DISCUSSION...
322 PM CST
THE WINTER SYSTEM IS STILL OFFERING PLENTY OF COMPLEXITIES INTO
TONIGHT AND FRIDAY MORNING...WITH TRANSITION TIME TO SNOW AND
TOTAL DURATION OF SNOW REMAINING THE MAIN CHALLENGES WITH THE
FORECAST.
WARM AIR ADVECTION DRIVEN PRECIPITATION...AT TIMES LARGE
SNOWFLAKES UNDER THE HIGHEST REFLECTIVITY...HAS LIFTED GRADUALLY
NORTH ACROSS THE AREA THROUGH THE AFTERNOON. THIS HAS BEEN ALONG A
TIGHTENING MID-LEVEL THERMAL GRADIENT WHICH SHOULD NOT MOVE MUCH
FURTHER NORTH AT ALL INTO TONIGHT. THIS OFFERS A LIKELY
INDICATION ON WHERE THE BANDED POTENTIAL AND HEAVIER PRECIPITATION
WILL BE TONIGHT AS THE UPPER WAVE APPROACHES. AT THE SURFACE
...LOW-LEVEL TEMPERATURES AND DEW POINTS HAVE DROPPED THIS
AFTERNOON UNDER PRECIP AND GRADUALLY BACKING WINDS. TEMPERATURES
SHOULD BASICALLY NOT CLIMB ANYMORE WITH THE MAIN WARM FRONT WELL
TO THE SOUTH JUST NORTH OF THE OHIO RIVER. PER VISIBLE
SATELLITE...MOISTURE AND INSTABILITY ARE EVIDENT LIFTING NORTH OF
THIS FRONT ACROSS CENTRAL IL AND IN...EVEN WITH A POSSIBLE
EMBEDDED DISTURBANCE. SCATTERED SHOWERS AND EVEN ELEVATED STORMS
ARE EXPECTED TO DEVELOP IN THAT AREA AND POTENTIALLY CLIP THE
SOUTHEAST FORECAST AREA THIS EVE.
THE MAIN UPPER SYSTEM CONTINUES TO ORGANIZE ACROSS THE MISSOURI
RIVER VALLEY IN ASSOCIATION WITH THE DIGGING 170 KT UPPER LEVEL
JET. AS THIS TRANSLATES EAST...LARGE SCALE ASCENT WILL OVERRIDE
THE EXISTING MID-LEVEL BOUNDARY AND LIKELY LEAD TO A RE-
ENHANCEMENT OF PRECIP EARLY THIS EVENING. STRENGTHENING SYSTEM
MOISTURE RETURN ON A LOW-LEVEL JET...ALMOST MORE OF A LOW LEVEL
/900-750MB/ TROWAL...WILL WRAP INTO THE AREA AS WELL. THE LAPSE
RATES WILL STEEPEN ALOFT THROUGH THE DIFFERENTIAL TEMPERATURE
ADVECTION AND SHOULD BE ENOUGH TO SUPPORT HEAVIER PRECIP RATES
AND MAXIMIZING THE INITIAL HIGH LOW LEVEL MIXING RATIOS OF 3 TO 4
G/KG. THERE REMAINS THAT CHANCE FOR THUNDER WITH THE
INSTABILITY...WHICH WOULD LEAD TO TEMPORARY VERY HEAVY PRECIP
RATES.
OVERALL THE INCREASING SUPPORT FOR MORE STEADY AND WIDESPREAD
PRECIP WILL SUPPORT DYNAMIC COOLING. THAT COUPLED WITH THE COOLING
FROM THE DIURNAL TREND AND SLIGHT COOL ADVECTION WILL WARRANT RAIN
CHANGING TO A MORE PREVALENT SNOW FROM WEST TO EAST ACROSS THE
ADVISORY AREA THIS EVENING...MAINLY PRIOR TO 10 PM. ALREADY
THROUGH BRIGHT BANDING AND DUAL-POL PRODUCTS THE MELTING LAYER IS
NOT FAR ALOFT AT ALL ACROSS THE ENTIRE AREA. THE TIMING OF
CHANGEOVER WILL DIRECTLY IMPACT HOW MUCH SNOW...AS SOME OF THE
HEAVIER RATES ARE FAVORED IN THE HOURS IMMEDIATELY AFTER CHANGE
OVER DUE TO MID-LEVEL FGEN AND INSTABILITY. THERE SHOULD BE A
TIGHT GRADIENT IN SNOWFALL THROUGH THIS EVENING...WITH AREAS ALONG
AND SOUTH OF INTERSTATE 80 NOT EXPECTED TO SEE ANY ACCUMULATION
BASICALLY...AND THAT DEMARCATION MAY EVEN BE FURTHER NORTH TOWARDS
THE U.S. HIGHWAY 34. HAVE GUIDED ON QPF CLOSE TO THE 12Z/18Z NAM
AND 09Z SREF...WITH RATIOS ADJUSTED QUITE LOW AND GRADUALLY
INCREASING TOWARDS 15 TO 1 TOWARDS ROCKFORD WHERE DENDRITIC GROWTH
LAYER IS DEEPER.
BY LATE EVENING INTO OVERNIGHT...THE SYSTEM 850 AND 700 MB LOWS
WILL PASS OVER /OR AT THEIR CLOSEST POINT TO/ THE AREA.
DEFORMATION IS INDICATED BY ALL GUIDANCE IN THIS TIME. PRECIP TYPE
WILL TRANSITION TO SNOW OVER ALMOST THE ENTIRE AREA...BUT THE
DEEPEST MOISTURE AND INSTABILITY/NEGATIVE EPV WILL GRADUALLY BE
WANING. THE TREND IN THE EC AND NAM/SREF HAS BEEN SLOWER WITH
REMOVING THE SYSTEM...WITH ALMOST A SECONDARY FLARE UP IN THE
MORNING AS THE POSITIVELY TILTED UPPER TROUGH SHIFTS EAST. SO HAVE
HELD ON TO ACCUMULATING SNOW LONGER...ESPECIALLY ACROSS CHICAGO
AND NORTHWEST IN. EVEN SOME LAKE ENHANCEMENT IS POSSIBLE LATE
TONIGHT INTO FRIDAY MORNING. AMOUNTS AFTER DAYBREAK OF AROUND ONE
INCH ARE EXPECTED IN FAR NORTHEAST IL INTO NORTHWEST IN...WHERE
SLIGHTLY HIGHER AMOUNTS MAY OCCUR.
STORM TOTAL SNOWFALL ACCUMULATIONS THROUGH FRIDAY MORNING ARE 4 TO
7 INCHES ACROSS MUCH OF THE ADVISORY AREA...OUTSIDE OF THE
SOUTHERN COUNTIES /I-80 CORRIDOR/ WHICH HAVE QUITE A TIGHT
GRADIENT IN TOTAL SNOWFALL FORECAST. ANY LOCATIONS THAT SEE SOME
OF THE PERSISTENT HEAVIER RATES...OR THUNDER SNOW...WILL END UP
HAVING HIGHER AMOUNTS ESPECIALLY DURING THIS EVENING. A SHORT FUSE
WINTER STORM WARNING MAY BE NEEDED FOR A WHILE IF THE BANDING IS A
PARTICULARLY STRONG AND STAGNANT SIGNATURE. WITH THE TIMING OF THE
HEAVIEST SNOW BEING AT THE TAIL END AND AFTER THE EVENING RUSH
HOUR...AND RATES GRADUALLY DIMINISHING DURING THE DAYBREAK
TIME...PUBLIC IMPACTS WOULD SEEM TO BE SLIGHTLY LOWER. SO CONTINUE
TO GO WITH THE ADVISORY AT THIS TIME.
MTF
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY...
320 PM...LIGHT SNOW OR SNOW SHOWERS LIKELY TO STILL BE ONGOING
FRIDAY EVENING AS THE LOW LIFTS NORTHEAST AND COLDER AIR ADVECTS
ACROSS THE AREA. EXPECT SNOW SHOWERS TO DECREASE IN COVERAGE AND
INTENSITY THROUGH THE NIGHT BUT STILL THE POTENTIAL FOR SOME
ADDITIONAL...THOUGH MINOR ACCUMULATION FRIDAY EVENING ESPECIALLY
ACROSS NORTHEAST IL INTO NORTHWEST INDIANA. WITH AT LEAST SOME
PARTIAL CLEARING IN ADDITION TO THE COLD AIR ADVECTION...EXPECT
TEMPS TO DIP INTO THE TEENS ACROSS NORTHWEST IL AND GIVEN THE
EXPECTED SNOWFALL TONIGHT...TEMPS COULD DROP EVEN FURTHER WITH
THE FRESH SNOWPACK.
THE WEEKEND IS LOOKING FAIRLY QUIET AS A LARGE RIDGE OF HIGH
PRESSURE BUILDS ACROSS THE REGION ON SATURDAY...SHIFTING EAST
SATURDAY NIGHT INTO SUNDAY. DESPITE SUNSHINE...AIRMASS REMAINS
FAIRLY COLD SATURDAY COMBINED WITH THE SNOWPACK...HIGHS MAY ONLY
REACH LOW/MID 30S. WITH LIGHT WINDS AND CLEAR SKIES...SHOULD SEE
A QUICK DROP IN TEMPS SATURDAY EVENING BUT WITH STRONG WARMING
ALOFT OVERNIGHT...TEMPS LIKELY TO BECOME STEADY OR EVEN BEGIN
RISING A FEW DEGREES OVERNIGHT INTO SUNDAY MORNING.
ANOTHER STORM SYSTEM THEN MOVES EAST ACROSS THE UPPER MIDWEST AND
NORTHERN LAKES SUNDAY AND SUNDAY NIGHT AND IT APPEARS THE BULK OF
THE PRECIP WITH THIS SYSTEM WILL REMAIN NORTH OF THE CWA BUT AS A
WEAK COLD FRONT MOVES ACROSS THE AREA SUNDAY NIGHT...THERE COULD BE
A PASSING SNOW OR RAIN SHOWER SUNDAY NIGHT AND HAVE MAINTAINED LOW
CHANCE POPS DURING THIS TIME. WITH STRONG WARMING CONTINUING SUNDAY
AHEAD OF THIS STORM SYSTEM...DEWPOINTS RECOVER INTO THE LOWER 30S
AND DESPITE THE SNOWPACK...TEMPS HAVE THE POTENTIAL TO WARM INTO
THE 40S...PERHAPS EVEN WARMER SOUTH OF WHEREVER THE MORE
SIGNIFICANT SNOW PACK ENDS UP FALLING OVER THE NEXT DAY.
THEN COMES NEXT WEEK AND THE POTENTIAL FOR ANOTHER SIMILAR STORM
TO THE ONE TO AFFECT THE AREA TONIGHT. MODELS DIFFER ON THE OVERALL
TIMING/PROGRESSION OF THIS STORM SYSTEM WITH THE ECMWF MUCH DEEPER
AND SLOWER WITH THE LOW NOT MOVING EAST ACROSS THE AREA UNTIL
WEDNESDAY AFTERNOON...WHICH IS MUCH SLOWER THAN THE WEAKER/FASTER
GFS. APPEARS LOW LEVELS WILL BE WARM ENOUGH TO SUPPORT ALL RAIN
UNTIL THE LOW MOVES EAST WHEN PRECIP COULD QUICKLY CHANGE TO SNOW
BEFORE ENDING. TOO FAR OUT IN TIME FOR SPECIFICS AND ALSO KEPT
MENTION OF RAIN OR SNOW OVER MUCH OF THE NORTHERN CWA. CMS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 08Z...
* -RAPLSN CHANGING TO -SN AT MDW NEXT 1-2 HRS.
* PERIOD OF MOST INTENSE SNOWFALL EXPECTED 10/11Z UNTIL APPROX
13/14Z THEN DECREASING IN INTENSITY...VSBY TO AROUND 1/2SM
POSSIBLE AT TIMES.
* IFR/LIFR CIGS PERSIST THROUGH MID MORNING THEN IMPROVE AND
BECOME MORE VARIABLE LATE MORNING.
* NE WINDS TURNING NORTH THEN NORTHWEST THROUGH MIDDAY WITH GUSTS
INCREASING INTO THE MID 20S KT.
* ADDITIONAL SCATTERED SNOW SHOWERS POSSIBLE MID/LATE AFTERNOON
WITH IFR VSBY POSSIBLE.
MDB
//DISCUSSION...UPDATED 08Z...
SNOW BECOMING MORE WIDESPREAD IN COVERAGE ACROSS CENTRAL AND
WESTERN SECTIONS OF THE CHI METRO AS A MID LEVEL SPEED MAX ARRIVES
FROM THE SOUTHWEST WITH THE MAIN UPPER TROUGH AXIS PIVOTING
ACROSS THE MISSISSIPPI RIVER. HEAVIEST BAND OF SNOW EXTENDS FROM
NEAR KJVL TO KDVN TO KMPZ AND CONTINUES TO SWING EASTWARD. LATEST
TRENDS SUPPORT A SLIGHTLY SLOWER ARRIVAL WITH IT REACHING THE CHI
METRO TERMINALS TOWARD 10/11Z BUT CLEARING RFD IN THE 12/13Z OR SO
TIME FRAME. TIMING MAY NEED TO BE SLOWED SLIGHTLY. UNTIL
THE...EXPECT VARIABLE VSBY CONDS IN -SN WITH MIXED PRECIP CHANGING
TO SNOW AT MDW IN THE NEXT 1-2 HRS. ONE OTHER CONCERN IS POTENTIAL
FOR A VERY SHORT WINDOW OF LAKE ENHANCEMENT OF THE MAIN BAND
TOWARD DAYBREAK AS AIR ALOFT BECOMES COLD ENOUGH FOR A LAKE
RESPONSE AND WINDS REMAIN JUST EAST OF NORTH. WILL NEED TO KEEP AN
EYE ON THIS AS IT MAY RESULT IN A SHORT PERIOD OF MORE INTENSE
SNOWFALL AND 1/4SM VSBY IN THE CHI METRO BUT THIS LOOKS TO BE A
LOW CHANCE SCENARIO WITH MARGINAL PARAMETERS AND WOULD BE VERY
SHORT LIVED BEFORE WINDS TURN JUST WEST OF NORTH.
MDB
FROM 06Z...
BAND OF MODERATE TO OCCASIONALLY HEAVY SNOW HAS BECOME FAIRLY
WELL SITUATED FROM S WI/FAR N IL WSW INTO SOUTHERN IA. TO THE
SOUTH OF THIS BAND WDLY SCTD RAIN/SNOW/GRAUPEL SHOWERS HAVE BEEN
COMMON WITH SOME DZ/BR IN BETWEEN THE SHOWERS. AS UPPER LOW OVER
IA PIVOTS EASTWARD LOOK FOR BAND OF MOD-HEAVY SNOW TO MIGRATE
SOUTHEASTWARD INTO THE CHGO METRO TERMINALS. PRESENCE OF STEEP MID
LEVEL LAPSE RATES AND FAIRLY STRONG ASCENT CERTAINLY SUGGEST SOME
POTENTIAL FOR SOME HEAVIER ELEMENTS AND POSSIBLY EVEN A RUMBLE OF
THUNDER.
ORGANIZED SYSTEM SNOW SHOULD PULL OUT FRIDAY MORNING WITH CLOUDY
AND BLUSTERY CONDITIONS IN ITS WAKE. FORECAST SOUNDINGS SUGGEST
NOT ONLY STRONG/GUSTY WINDS WITH GUSTS OF 25-30KT PROBABLE.
ALSO...VERY STEEP LOW AND MID LEVEL LAPSE RATES WITH FAIRLY HIGH
BOUNDARY LAYER MOISTURE MEANS IT WILL TAKE RELATIVELY LITTLE TO
KICK OF SOME FRISKY SNOW SHOWERS DURING THE AFTERNOON FRIDAY.
MODELS DO SUGGEST A WEAK WAVE WILL ROTATE SOUTHEAST INTO THE AREA
LATER FRIDAY AFTERNOON AND HAVE KEYED IN ON THAT TIMING FOR A
PROB30 OF SHSN.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 08Z...
* MEDIUM-HIGH CONFIDENCE IN MIXED PRECIP TURNING TO SNOW AT MDW.
* MEDIUM-HIGH CONFIDENCE IN HEAVIEST SNOW OCCURRING 10/11Z UNTIL
APPROX 13/14Z...MEDIUM CONFIDENCE ON VSBY TO AROUND 1/2SM AT TIMES.
* HIGH CONFIDENCE IFR/LIFR CIGS CONTINUING THROUGH MID MORNING
WITH UPWARD TREND INTO EARLY AFTERNOON...MEDIUM CONFIDENCE IN
SPECIFIC TIMING.
* HIGH CONFIDENCE IN WIND TRENDS.
* LOW-MEDIUM CONFIDENCE IN SHSN THREAT THIS AFTERNOON.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 08Z...
SATURDAY...VFR.
SUNDAY...VFR AND WINDY FROM THE SOUTH/SOUTHWEST.
MONDAY...VFR.
TUESDAY...CHANCE FOR RAIN/SNOW...POSSIBLE MVFR.
WEDNESDAY...CHANCE FOR RAIN/SNOW...POSSIBLE MVFR.
MDB
&&
.MARINE...
116 PM CST
AN ACTIVE WEATHER PATTERN IS IN STORE FOR THE NEXT SEVERAL DAYS.
LOW PRESSURE WILL DEEPEN AS IT MOVES FROM SOUTHERN MISSOURI THIS
AFTERNOON TO THE EASTERN LAKES FRIDAY AFTERNOON. WINDS WILL BACK
FROM EAST TO NORTHWEST AND STRENGTHEN OVER LAKE MICHIGAN. SOME
GALE FORCE GUSTS ARE POSSIBLE OVER SOUTHERN LAKE MICHIGAN FRIDAY
MORNING...BUT FEEL IT WILL BE A SHORT DURATION EVENT AND WILL HOLD
OFF ON GALE HEADLINES FOR NOW. WILL CONTINUE WITH SMALL CRAFT
ADVISORY FOR THE IL AND IN NEARSHORE AREA. A RIDGE OF HIGH
PRESSURE WILL MOVE ACROSS LAKE MICHIGAN SATURDAY NIGHT BEFORE
ANOTHER LOW PRESSURE APPROACHES SUNDAY AND SUNDAY NIGHT. THIS LOW
WILL TAKE A PATH FURTHER NORTH FROM THE NORTHERN PLAINS TO LAKE
SUPERIOR...GENERATING MODERATELY STRONG SOUTHWEST FLOW OVER LAKE
MICHIGAN. THE NEXT STORM SYSTEM WILL MOVE ACROSS IL AND IN AROUND
WEDNESDAY.
ALLSOPP
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ006-ILZ013-ILZ014-ILZ022 UNTIL 9 AM
FRIDAY.
WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ019-ILZ020 UNTIL 6 AM FRIDAY.
IN...WINTER WEATHER ADVISORY...INZ001-INZ002 UNTIL 9 AM FRIDAY.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 4 PM FRIDAY.
SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1046 PM CST THU FEB 23 2012
.DISCUSSION...
901 PM CST
NO CHANGES TO GOING ADVISORY HEADLINES THIS EVENING. HOWEVER...
FORECAST REMAINS QUITE COMPLEX WITH RESPECT TO SNOW AMOUNTS AND
PRECIP TYPES THROUGH THE EARLY OVERNIGHT HOURS.
EVENING VAPOR IMAGERY SHOWS STRONG SHORT WAVE TROUGH DIGGING
EAST-SOUTHEAST ACROSS IA/MO. MAIN SFC LOW WAS OVER SOUTHERN INDIANA
WITH TROUGH TRAILING BACK THROUGH WESTERN IL/SOUTHERN IA. INITIAL
PUSH OF WARM ADVECTION RAIN/SNOW HAD GENERALLY LIFTED TO/NORTH OF
THE WI BORDER DURING THE EVENING HOURS...WHILE FARTHER TO THE WEST
REGIONAL RADAR MOSAIC DEPICTED EXTENSION OF BROAD DEVELOPING
DEFORMATION BAND FROM SOUTHWEST IA INTO SOUTHERN WI. EVIDENCE OF
FRONTOGENETICALLY FORCED ENHANCED PRECIPITATION WAS NOTED ACROSS FAR
EASTERN IA...JUST NORTH OF THE QUAD CITIES.
MUCH OF THE CWA HAS SEEN A LULL IN MORE ORGANIZED MEASURABLE PRECIP
DURING THE EVENING HOURS. 22-23Z RUNS OF THE HRRR SEEM TO HAVE A
VERY GOOD HANDLE ON TRENDS ACROSS THE REGION THROUGH MID-EVENING...
AND WOULD SUGGEST DEFORMATION PRECIP AXIS WILL GRADUALLY TRANSLATE
EAST ACROSS THE AREA DURING THE OVERNIGHT/FRIDAY MORNING HOURS.
WHILE THE CURRENT BAND NEAR DVN IS IMPRESSIVE LOOKING...HIGH RES
SHORT TERM MODEL TRENDS WOULD SUGGEST THIS WOULD WEAKEN AND BECOME
SOMEWHAT LESS FOCUS AS IT TRANSLATES EASTWARD...THOUGH ENTIRE
DEFORMATION PRECIP AREA WILL LIKELY BECOME A BIT BETTER ORGANIZED.
WITH LESS PRECIPITATION...ESPECIALLY IN THE FORM OF SNOW ACROSS THE
AREA DURING THE EARLY/MID EVENING HORUS...HAVE ADJUSTED SNOWFALL
AMOUNTS DOWN SOMEWHAT FROM PREVIOUS FORECAST...GENERALLY 2-6 INCHES
WITH THE HEAVIER AMOUNTS GENERALLY ALONG/NORTH OF INTERSTATE 88 IN
NORTHERN/NORTHEAST IL. SOME HIGHER AMOUNTS STILL NOT OUT OF THE
QUESTION GIVEN POTENTIAL FOR MESOSCALE BANDING...AND POTENTIAL FOR
CONVECTION...BUT OVERALL CONFIDENCE REMAINS FAIRLY LOW EVEN AT THIS
RELATIVELY CLOSE-IN TIME.
SOUTH OF ROUGHLY A DVN-ORD LINE HOWEVER...THE HRRR WOULD INDICATE
MORE CONVECTIVE SHOWERY TYPE PRECIP...WHICH HAS BEEN OCCURRING AS A
MIX OF RAIN/SNOW/GRAUPEL PER REPORTS IN UPSTREAM AREAS. THIS APPEARS
QUITE REASONABLE AS AREA OF STEEP MID-LEVEL LAPSE RATES...IN EXCESS
OF 7 DEG/KM PER RUC/SPC MESOANALYSIS...WILL CONTINUE TO SPREAD
ACROSS THE SOUTHERN PARTS OF THE CWFA OVERNIGHT. HAVE CONTINUED TO
INDICATE SHOWERS/CHANCE THUNDER CHANGING TO SNOW DURING THE
OVERNIGHT HOURS...WITH SNOWFALL AMOUNTS QUICKLY DECREASING THROUGH
THE I-80 CORRIDOR SOUTHWARD.
RATZER
//PREV DISCUSSION...
322 PM CST
THE WINTER SYSTEM IS STILL OFFERING PLENTY OF COMPLEXITIES INTO
TONIGHT AND FRIDAY MORNING...WITH TRANSITION TIME TO SNOW AND
TOTAL DURATION OF SNOW REMAINING THE MAIN CHALLENGES WITH THE
FORECAST.
WARM AIR ADVECTION DRIVEN PRECIPITATION...AT TIMES LARGE
SNOWFLAKES UNDER THE HIGHEST REFLECTIVITY...HAS LIFTED GRADUALLY
NORTH ACROSS THE AREA THROUGH THE AFTERNOON. THIS HAS BEEN ALONG A
TIGHTENING MID-LEVEL THERMAL GRADIENT WHICH SHOULD NOT MOVE MUCH
FURTHER NORTH AT ALL INTO TONIGHT. THIS OFFERS A LIKELY
INDICATION ON WHERE THE BANDED POTENTIAL AND HEAVIER PRECIPITATION
WILL BE TONIGHT AS THE UPPER WAVE APPROACHES. AT THE SURFACE
...LOW-LEVEL TEMPERATURES AND DEW POINTS HAVE DROPPED THIS
AFTERNOON UNDER PRECIP AND GRADUALLY BACKING WINDS. TEMPERATURES
SHOULD BASICALLY NOT CLIMB ANYMORE WITH THE MAIN WARM FRONT WELL
TO THE SOUTH JUST NORTH OF THE OHIO RIVER. PER VISIBLE
SATELLITE...MOISTURE AND INSTABILITY ARE EVIDENT LIFTING NORTH OF
THIS FRONT ACROSS CENTRAL IL AND IN...EVEN WITH A POSSIBLE
EMBEDDED DISTURBANCE. SCATTERED SHOWERS AND EVEN ELEVATED STORMS
ARE EXPECTED TO DEVELOP IN THAT AREA AND POTENTIALLY CLIP THE
SOUTHEAST FORECAST AREA THIS EVE.
THE MAIN UPPER SYSTEM CONTINUES TO ORGANIZE ACROSS THE MISSOURI
RIVER VALLEY IN ASSOCIATION WITH THE DIGGING 170 KT UPPER LEVEL
JET. AS THIS TRANSLATES EAST...LARGE SCALE ASCENT WILL OVERRIDE
THE EXISTING MID-LEVEL BOUNDARY AND LIKELY LEAD TO A RE-
ENHANCEMENT OF PRECIP EARLY THIS EVENING. STRENGTHENING SYSTEM
MOISTURE RETURN ON A LOW-LEVEL JET...ALMOST MORE OF A LOW LEVEL
/900-750MB/ TROWAL...WILL WRAP INTO THE AREA AS WELL. THE LAPSE
RATES WILL STEEPEN ALOFT THROUGH THE DIFFERENTIAL TEMPERATURE
ADVECTION AND SHOULD BE ENOUGH TO SUPPORT HEAVIER PRECIP RATES
AND MAXIMIZING THE INITIAL HIGH LOW LEVEL MIXING RATIOS OF 3 TO 4
G/KG. THERE REMAINS THAT CHANCE FOR THUNDER WITH THE
INSTABILITY...WHICH WOULD LEAD TO TEMPORARY VERY HEAVY PRECIP
RATES.
OVERALL THE INCREASING SUPPORT FOR MORE STEADY AND WIDESPREAD
PRECIP WILL SUPPORT DYNAMIC COOLING. THAT COUPLED WITH THE COOLING
FROM THE DIURNAL TREND AND SLIGHT COOL ADVECTION WILL WARRANT RAIN
CHANGING TO A MORE PREVALENT SNOW FROM WEST TO EAST ACROSS THE
ADVISORY AREA THIS EVENING...MAINLY PRIOR TO 10 PM. ALREADY
THROUGH BRIGHT BANDING AND DUAL-POL PRODUCTS THE MELTING LAYER IS
NOT FAR ALOFT AT ALL ACROSS THE ENTIRE AREA. THE TIMING OF
CHANGEOVER WILL DIRECTLY IMPACT HOW MUCH SNOW...AS SOME OF THE
HEAVIER RATES ARE FAVORED IN THE HOURS IMMEDIATELY AFTER CHANGE
OVER DUE TO MID-LEVEL FGEN AND INSTABILITY. THERE SHOULD BE A
TIGHT GRADIENT IN SNOWFALL THROUGH THIS EVENING...WITH AREAS ALONG
AND SOUTH OF INTERSTATE 80 NOT EXPECTED TO SEE ANY ACCUMULATION
BASICALLY...AND THAT DEMARCATION MAY EVEN BE FURTHER NORTH TOWARDS
THE U.S. HIGHWAY 34. HAVE GUIDED ON QPF CLOSE TO THE 12Z/18Z NAM
AND 09Z SREF...WITH RATIOS ADJUSTED QUITE LOW AND GRADUALLY
INCREASING TOWARDS 15 TO 1 TOWARDS ROCKFORD WHERE DENDRITIC GROWTH
LAYER IS DEEPER.
BY LATE EVENING INTO OVERNIGHT...THE SYSTEM 850 AND 700 MB LOWS
WILL PASS OVER /OR AT THEIR CLOSEST POINT TO/ THE AREA.
DEFORMATION IS INDICATED BY ALL GUIDANCE IN THIS TIME. PRECIP TYPE
WILL TRANSITION TO SNOW OVER ALMOST THE ENTIRE AREA...BUT THE
DEEPEST MOISTURE AND INSTABILITY/NEGATIVE EPV WILL GRADUALLY BE
WANING. THE TREND IN THE EC AND NAM/SREF HAS BEEN SLOWER WITH
REMOVING THE SYSTEM...WITH ALMOST A SECONDARY FLARE UP IN THE
MORNING AS THE POSITIVELY TILTED UPPER TROUGH SHIFTS EAST. SO HAVE
HELD ON TO ACCUMULATING SNOW LONGER...ESPECIALLY ACROSS CHICAGO
AND NORTHWEST IN. EVEN SOME LAKE ENHANCEMENT IS POSSIBLE LATE
TONIGHT INTO FRIDAY MORNING. AMOUNTS AFTER DAYBREAK OF AROUND ONE
INCH ARE EXPECTED IN FAR NORTHEAST IL INTO NORTHWEST IN...WHERE
SLIGHTLY HIGHER AMOUNTS MAY OCCUR.
STORM TOTAL SNOWFALL ACCUMULATIONS THROUGH FRIDAY MORNING ARE 4 TO
7 INCHES ACROSS MUCH OF THE ADVISORY AREA...OUTSIDE OF THE
SOUTHERN COUNTIES /I-80 CORRIDOR/ WHICH HAVE QUITE A TIGHT
GRADIENT IN TOTAL SNOWFALL FORECAST. ANY LOCATIONS THAT SEE SOME
OF THE PERSISTENT HEAVIER RATES...OR THUNDER SNOW...WILL END UP
HAVING HIGHER AMOUNTS ESPECIALLY DURING THIS EVENING. A SHORT FUSE
WINTER STORM WARNING MAY BE NEEDED FOR A WHILE IF THE BANDING IS A
PARTICULARLY STRONG AND STAGNANT SIGNATURE. WITH THE TIMING OF THE
HEAVIEST SNOW BEING AT THE TAIL END AND AFTER THE EVENING RUSH
HOUR...AND RATES GRADUALLY DIMINISHING DURING THE DAYBREAK
TIME...PUBLIC IMPACTS WOULD SEEM TO BE SLIGHTLY LOWER. SO CONTINUE
TO GO WITH THE ADVISORY AT THIS TIME.
MTF
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY...
320 PM...LIGHT SNOW OR SNOW SHOWERS LIKELY TO STILL BE ONGOING
FRIDAY EVENING AS THE LOW LIFTS NORTHEAST AND COLDER AIR ADVECTS
ACROSS THE AREA. EXPECT SNOW SHOWERS TO DECREASE IN COVERAGE AND
INTENSITY THROUGH THE NIGHT BUT STILL THE POTENTIAL FOR SOME
ADDITIONAL...THOUGH MINOR ACCUMULATION FRIDAY EVENING ESPECIALLY
ACROSS NORTHEAST IL INTO NORTHWEST INDIANA. WITH AT LEAST SOME
PARTIAL CLEARING IN ADDITION TO THE COLD AIR ADVECTION...EXPECT
TEMPS TO DIP INTO THE TEENS ACROSS NORTHWEST IL AND GIVEN THE
EXPECTED SNOWFALL TONIGHT...TEMPS COULD DROP EVEN FURTHER WITH
THE FRESH SNOWPACK.
THE WEEKEND IS LOOKING FAIRLY QUIET AS A LARGE RIDGE OF HIGH
PRESSURE BUILDS ACROSS THE REGION ON SATURDAY...SHIFTING EAST
SATURDAY NIGHT INTO SUNDAY. DESPITE SUNSHINE...AIRMASS REMAINS
FAIRLY COLD SATURDAY COMBINED WITH THE SNOWPACK...HIGHS MAY ONLY
REACH LOW/MID 30S. WITH LIGHT WINDS AND CLEAR SKIES...SHOULD SEE
A QUICK DROP IN TEMPS SATURDAY EVENING BUT WITH STRONG WARMING
ALOFT OVERNIGHT...TEMPS LIKELY TO BECOME STEADY OR EVEN BEGIN
RISING A FEW DEGREES OVERNIGHT INTO SUNDAY MORNING.
ANOTHER STORM SYSTEM THEN MOVES EAST ACROSS THE UPPER MIDWEST AND
NORTHERN LAKES SUNDAY AND SUNDAY NIGHT AND IT APPEARS THE BULK OF
THE PRECIP WITH THIS SYSTEM WILL REMAIN NORTH OF THE CWA BUT AS A
WEAK COLD FRONT MOVES ACROSS THE AREA SUNDAY NIGHT...THERE COULD BE
A PASSING SNOW OR RAIN SHOWER SUNDAY NIGHT AND HAVE MAINTAINED LOW
CHANCE POPS DURING THIS TIME. WITH STRONG WARMING CONTINUING SUNDAY
AHEAD OF THIS STORM SYSTEM...DEWPOINTS RECOVER INTO THE LOWER 30S
AND DESPITE THE SNOWPACK...TEMPS HAVE THE POTENTIAL TO WARM INTO
THE 40S...PERHAPS EVEN WARMER SOUTH OF WHEREVER THE MORE
SIGNIFICANT SNOW PACK ENDS UP FALLING OVER THE NEXT DAY.
THEN COMES NEXT WEEK AND THE POTENTIAL FOR ANOTHER SIMILAR STORM
TO THE ONE TO AFFECT THE AREA TONIGHT. MODELS DIFFER ON THE OVERALL
TIMING/PROGRESSION OF THIS STORM SYSTEM WITH THE ECMWF MUCH DEEPER
AND SLOWER WITH THE LOW NOT MOVING EAST ACROSS THE AREA UNTIL
WEDNESDAY AFTERNOON...WHICH IS MUCH SLOWER THAN THE WEAKER/FASTER
GFS. APPEARS LOW LEVELS WILL BE WARM ENOUGH TO SUPPORT ALL RAIN
UNTIL THE LOW MOVES EAST WHEN PRECIP COULD QUICKLY CHANGE TO SNOW
BEFORE ENDING. TOO FAR OUT IN TIME FOR SPECIFICS AND ALSO KEPT
MENTION OF RAIN OR SNOW OVER MUCH OF THE NORTHERN CWA. CMS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* RA/DZ/SN TRANSITIONS TO ALL WET SNOW OVERNIGHT
* IFR/LIFR CIGS LIKELY TO PERSIST INTO FRI MORNING
* WET SNOW TAPERS OFF FRI MORNING, FLURRIES POSSIBLY LINGER
* SCTD SHSN POSSIBLE AGAIN FRIDAY AFTERNOON/EARLY EVENING
* CIGS/VSBY CLIMB ABOVE IFR FRIDAY AFTERNOON OUTSIDE ANY SHSN
IZZI
//DISCUSSION...UPDATED 06Z...
BAND OF MODERATE TO OCCASIONALLY HEAVY SNOW HAS BECOME FAIRLY
WELL SITUATED FROM S WI/FAR N IL WSW INTO SOUTHERN IA. TO THE
SOUTH OF THIS BAND WDLY SCTD RAIN/SNOW/GRAUPEL SHOWERS HAVE BEEN
COMMON WITH SOME DZ/BR IN BETWEEN THE SHOWERS. AS UPPER LOW OVER
IA PIVOTS EASTWARD LOOK FOR BAND OF MOD-HEAVY SNOW TO MIGRATE
SOUTHEASTWARD INTO THE CHGO METRO TERMINALS. PRESENCE OF STEEP MID
LEVEL LAPSE RATES AND FAIRLY STRONG ASCENT CERTAINLY SUGGEST SOME
POTENTIAL FOR SOME HEAVIER ELEMENTS AND POSSIBLY EVEN A RUMBLE OF
THUNDER.
ORGANIZED SYSTEM SNOW SHOULD PULL OUT FRIDAY MORNING WITH CLOUDY
AND BLUSTERY CONDITIONS IN ITS WAKE. FORECAST SOUNDINGS SUGGEST
NOT ONLY STRONG/GUSTY WINDS WITH GUSTS OF 25-30KT PROBABLE.
ALSO...VERY STEEP LOW AND MID LEVEL LAPSE RATES WITH FAIRLY HIGH
BOUNDARY LAYER MOISTURE MEANS IT WILL TAKE RELATIVELY LITTLE TO
KICK OF SOME FRISKY SNOW SHOWERS DURING THE AFTERNOON FRIDAY.
MODELS DO SUGGEST A WEAK WAVE WILL ROTATE SOUTHEAST INTO THE AREA
LATER FRIDAY AFTERNOON AND HAVE KEYED IN ON THAT TIMING FOR A
PROB30 OF SHSN.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 04Z...
* HIGH CONFIDENCE IN PRECIP CHANGING TO ALL SNOW
* MEDIUM CONFIDENCE ON TIMING
* HIGH CONFIDENCE ON ACCUMULATING SNOW ENDING BY AROUND 15Z
* LOW CONFIDENCE ON SHSN THREAT FRIDAY AFTERNOON
* HIGH CONFIDENCE ON WIND/CIG TRENDS.
IZZI
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SATURDAY...VFR.
SUNDAY...SLIGHT CHANCE OF SHOWERS...OTHERWISE VFR.
MONDAY...VFR.
TUESDAY...CHANCE FOR RAIN/SNOW...POSSIBLE MVFR.
WEDNESDAY...CHANCE FOR RAIN...POSSIBLE MVFR.
RODRIGUEZ
&&
.MARINE...
116 PM CST
AN ACTIVE WEATHER PATTERN IS IN STORE FOR THE NEXT SEVERAL DAYS.
LOW PRESSURE WILL DEEPEN AS IT MOVES FROM SOUTHERN MISSOURI THIS
AFTERNOON TO THE EASTERN LAKES FRIDAY AFTERNOON. WINDS WILL BACK
FROM EAST TO NORTHWEST AND STRENGTHEN OVER LAKE MICHIGAN. SOME
GALE FORCE GUSTS ARE POSSIBLE OVER SOUTHERN LAKE MICHIGAN FRIDAY
MORNING...BUT FEEL IT WILL BE A SHORT DURATION EVENT AND WILL HOLD
OFF ON GALE HEADLINES FOR NOW. WILL CONTINUE WITH SMALL CRAFT
ADVISORY FOR THE IL AND IN NEARSHORE AREA. A RIDGE OF HIGH
PRESSURE WILL MOVE ACROSS LAKE MICHIGAN SATURDAY NIGHT BEFORE
ANOTHER LOW PRESSURE APPROACHES SUNDAY AND SUNDAY NIGHT. THIS LOW
WILL TAKE A PATH FURTHER NORTH FROM THE NORTHERN PLAINS TO LAKE
SUPERIOR...GENERATING MODERATELY STRONG SOUTHWEST FLOW OVER LAKE
MICHIGAN. THE NEXT STORM SYSTEM WILL MOVE ACROSS IL AND IN AROUND
WEDNESDAY.
ALLSOPP
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ006-ILZ013-ILZ014-ILZ022 UNTIL 9 AM
FRIDAY.
WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ019-ILZ020 UNTIL 6 AM FRIDAY.
IN...WINTER WEATHER ADVISORY...INZ001-INZ002 UNTIL 9 AM FRIDAY.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 4 PM FRIDAY.
SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1007 PM CST THU FEB 23 2012
.DISCUSSION...
901 PM CST
NO CHANGES TO GOING ADVISORY HEADLINES THIS EVENING. HOWEVER...
FORECAST REMAINS QUITE COMPLEX WITH RESPECT TO SNOW AMOUNTS AND
PRECIP TYPES THROUGH THE EARLY OVERNIGHT HOURS.
EVENING VAPOR IMAGERY SHOWS STRONG SHORT WAVE TROUGH DIGGING
EAST-SOUTHEAST ACROSS IA/MO. MAIN SFC LOW WAS OVER SOUTHERN INDIANA
WITH TROUGH TRAILING BACK THROUGH WESTERN IL/SOUTHERN IA. INITIAL
PUSH OF WARM ADVECTION RAIN/SNOW HAD GENERALLY LIFTED TO/NORTH OF
THE WI BORDER DURING THE EVENING HOURS...WHILE FARTHER TO THE WEST
REGIONAL RADAR MOSAIC DEPICTED EXTENSION OF BROAD DEVELOPING
DEFORMATION BAND FROM SOUTHWEST IA INTO SOUTHERN WI. EVIDENCE OF
FRONTOGENETICALLY FORCED ENHANCED PRECIPITATION WAS NOTED ACROSS FAR
EASTERN IA...JUST NORTH OF THE QUAD CITIES.
MUCH OF THE CWA HAS SEEN A LULL IN MORE ORGANIZED MEASURABLE PRECIP
DURING THE EVENING HOURS. 22-23Z RUNS OF THE HRRR SEEM TO HAVE A
VERY GOOD HANDLE ON TRENDS ACROSS THE REGION THROUGH MID-EVENING...
AND WOULD SUGGEST DEFORMATION PRECIP AXIS WILL GRADUALLY TRANSLATE
EAST ACROSS THE AREA DURING THE OVERNIGHT/FRIDAY MORNING HOURS.
WHILE THE CURRENT BAND NEAR DVN IS IMPRESSIVE LOOKING...HIGH RES
SHORT TERM MODEL TRENDS WOULD SUGGEST THIS WOULD WEAKEN AND BECOME
SOMEWHAT LESS FOCUS AS IT TRANSLATES EASTWARD...THOUGH ENTIRE
DEFORMATION PRECIP AREA WILL LIKELY BECOME A BIT BETTER ORGANIZED.
WITH LESS PRECIPITATION...ESPECIALLY IN THE FORM OF SNOW ACROSS THE
AREA DURING THE EARLY/MID EVENING HORUS...HAVE ADJUSTED SNOWFALL
AMOUNTS DOWN SOMEWHAT FROM PREVIOUS FORECAST...GENERALLY 2-6 INCHES
WITH THE HEAVIER AMOUNTS GENERALLY ALONG/NORTH OF INTERSTATE 88 IN
NORTHERN/NORTHEAST IL. SOME HIGHER AMOUNTS STILL NOT OUT OF THE
QUESTION GIVEN POTENTIAL FOR MESOSCALE BANDING...AND POTENTIAL FOR
CONVECTION...BUT OVERALL CONFIDENCE REMAINS FAIRLY LOW EVEN AT THIS
RELATIVELY CLOSE-IN TIME.
SOUTH OF ROUGHLY A DVN-ORD LINE HOWEVER...THE HRRR WOULD INDICATE
MORE CONVECTIVE SHOWERY TYPE PRECIP...WHICH HAS BEEN OCCURRING AS A
MIX OF RAIN/SNOW/GRAUPEL PER REPORTS IN UPSTREAM AREAS. THIS APPEARS
QUITE REASONABLE AS AREA OF STEEP MID-LEVEL LAPSE RATES...IN EXCESS
OF 7 DEG/KM PER RUC/SPC MESOANALYSIS...WILL CONTINUE TO SPREAD
ACROSS THE SOUTHERN PARTS OF THE CWFA OVERNIGHT. HAVE CONTINUED TO
INDICATE SHOWERS/CHANCE THUNDER CHANGING TO SNOW DURING THE
OVERNIGHT HOURS...WITH SNOWFALL AMOUNTS QUICKLY DECREASING THROUGH
THE I-80 CORRIDOR SOUTHWARD.
RATZER
//PREV DISCUSSION...
322 PM CST
THE WINTER SYSTEM IS STILL OFFERING PLENTY OF COMPLEXITIES INTO
TONIGHT AND FRIDAY MORNING...WITH TRANSITION TIME TO SNOW AND
TOTAL DURATION OF SNOW REMAINING THE MAIN CHALLENGES WITH THE
FORECAST.
WARM AIR ADVECTION DRIVEN PRECIPITATION...AT TIMES LARGE
SNOWFLAKES UNDER THE HIGHEST REFLECTIVITY...HAS LIFTED GRADUALLY
NORTH ACROSS THE AREA THROUGH THE AFTERNOON. THIS HAS BEEN ALONG A
TIGHTENING MID-LEVEL THERMAL GRADIENT WHICH SHOULD NOT MOVE MUCH
FURTHER NORTH AT ALL INTO TONIGHT. THIS OFFERS A LIKELY
INDICATION ON WHERE THE BANDED POTENTIAL AND HEAVIER PRECIPITATION
WILL BE TONIGHT AS THE UPPER WAVE APPROACHES. AT THE SURFACE
...LOW-LEVEL TEMPERATURES AND DEW POINTS HAVE DROPPED THIS
AFTERNOON UNDER PRECIP AND GRADUALLY BACKING WINDS. TEMPERATURES
SHOULD BASICALLY NOT CLIMB ANYMORE WITH THE MAIN WARM FRONT WELL
TO THE SOUTH JUST NORTH OF THE OHIO RIVER. PER VISIBLE
SATELLITE...MOISTURE AND INSTABILITY ARE EVIDENT LIFTING NORTH OF
THIS FRONT ACROSS CENTRAL IL AND IN...EVEN WITH A POSSIBLE
EMBEDDED DISTURBANCE. SCATTERED SHOWERS AND EVEN ELEVATED STORMS
ARE EXPECTED TO DEVELOP IN THAT AREA AND POTENTIALLY CLIP THE
SOUTHEAST FORECAST AREA THIS EVE.
THE MAIN UPPER SYSTEM CONTINUES TO ORGANIZE ACROSS THE MISSOURI
RIVER VALLEY IN ASSOCIATION WITH THE DIGGING 170 KT UPPER LEVEL
JET. AS THIS TRANSLATES EAST...LARGE SCALE ASCENT WILL OVERRIDE
THE EXISTING MID-LEVEL BOUNDARY AND LIKELY LEAD TO A RE-
ENHANCEMENT OF PRECIP EARLY THIS EVENING. STRENGTHENING SYSTEM
MOISTURE RETURN ON A LOW-LEVEL JET...ALMOST MORE OF A LOW LEVEL
/900-750MB/ TROWAL...WILL WRAP INTO THE AREA AS WELL. THE LAPSE
RATES WILL STEEPEN ALOFT THROUGH THE DIFFERENTIAL TEMPERATURE
ADVECTION AND SHOULD BE ENOUGH TO SUPPORT HEAVIER PRECIP RATES
AND MAXIMIZING THE INITIAL HIGH LOW LEVEL MIXING RATIOS OF 3 TO 4
G/KG. THERE REMAINS THAT CHANCE FOR THUNDER WITH THE
INSTABILITY...WHICH WOULD LEAD TO TEMPORARY VERY HEAVY PRECIP
RATES.
OVERALL THE INCREASING SUPPORT FOR MORE STEADY AND WIDESPREAD
PRECIP WILL SUPPORT DYNAMIC COOLING. THAT COUPLED WITH THE COOLING
FROM THE DIURNAL TREND AND SLIGHT COOL ADVECTION WILL WARRANT RAIN
CHANGING TO A MORE PREVALENT SNOW FROM WEST TO EAST ACROSS THE
ADVISORY AREA THIS EVENING...MAINLY PRIOR TO 10 PM. ALREADY
THROUGH BRIGHT BANDING AND DUAL-POL PRODUCTS THE MELTING LAYER IS
NOT FAR ALOFT AT ALL ACROSS THE ENTIRE AREA. THE TIMING OF
CHANGEOVER WILL DIRECTLY IMPACT HOW MUCH SNOW...AS SOME OF THE
HEAVIER RATES ARE FAVORED IN THE HOURS IMMEDIATELY AFTER CHANGE
OVER DUE TO MID-LEVEL FGEN AND INSTABILITY. THERE SHOULD BE A
TIGHT GRADIENT IN SNOWFALL THROUGH THIS EVENING...WITH AREAS ALONG
AND SOUTH OF INTERSTATE 80 NOT EXPECTED TO SEE ANY ACCUMULATION
BASICALLY...AND THAT DEMARCATION MAY EVEN BE FURTHER NORTH TOWARDS
THE U.S. HIGHWAY 34. HAVE GUIDED ON QPF CLOSE TO THE 12Z/18Z NAM
AND 09Z SREF...WITH RATIOS ADJUSTED QUITE LOW AND GRADUALLY
INCREASING TOWARDS 15 TO 1 TOWARDS ROCKFORD WHERE DENDRITIC GROWTH
LAYER IS DEEPER.
BY LATE EVENING INTO OVERNIGHT...THE SYSTEM 850 AND 700 MB LOWS
WILL PASS OVER /OR AT THEIR CLOSEST POINT TO/ THE AREA.
DEFORMATION IS INDICATED BY ALL GUIDANCE IN THIS TIME. PRECIP TYPE
WILL TRANSITION TO SNOW OVER ALMOST THE ENTIRE AREA...BUT THE
DEEPEST MOISTURE AND INSTABILITY/NEGATIVE EPV WILL GRADUALLY BE
WANING. THE TREND IN THE EC AND NAM/SREF HAS BEEN SLOWER WITH
REMOVING THE SYSTEM...WITH ALMOST A SECONDARY FLARE UP IN THE
MORNING AS THE POSITIVELY TILTED UPPER TROUGH SHIFTS EAST. SO HAVE
HELD ON TO ACCUMULATING SNOW LONGER...ESPECIALLY ACROSS CHICAGO
AND NORTHWEST IN. EVEN SOME LAKE ENHANCEMENT IS POSSIBLE LATE
TONIGHT INTO FRIDAY MORNING. AMOUNTS AFTER DAYBREAK OF AROUND ONE
INCH ARE EXPECTED IN FAR NORTHEAST IL INTO NORTHWEST IN...WHERE
SLIGHTLY HIGHER AMOUNTS MAY OCCUR.
STORM TOTAL SNOWFALL ACCUMULATIONS THROUGH FRIDAY MORNING ARE 4 TO
7 INCHES ACROSS MUCH OF THE ADVISORY AREA...OUTSIDE OF THE
SOUTHERN COUNTIES /I-80 CORRIDOR/ WHICH HAVE QUITE A TIGHT
GRADIENT IN TOTAL SNOWFALL FORECAST. ANY LOCATIONS THAT SEE SOME
OF THE PERSISTENT HEAVIER RATES...OR THUNDER SNOW...WILL END UP
HAVING HIGHER AMOUNTS ESPECIALLY DURING THIS EVENING. A SHORT FUSE
WINTER STORM WARNING MAY BE NEEDED FOR A WHILE IF THE BANDING IS A
PARTICULARLY STRONG AND STAGNANT SIGNATURE. WITH THE TIMING OF THE
HEAVIEST SNOW BEING AT THE TAIL END AND AFTER THE EVENING RUSH
HOUR...AND RATES GRADUALLY DIMINISHING DURING THE DAYBREAK
TIME...PUBLIC IMPACTS WOULD SEEM TO BE SLIGHTLY LOWER. SO CONTINUE
TO GO WITH THE ADVISORY AT THIS TIME.
MTF
LONG TERM...FRIDAY NIGHT THROUGH THURSDAY...
320 PM...LIGHT SNOW OR SNOW SHOWERS LIKELY TO STILL BE ONGOING
FRIDAY EVENING AS THE LOW LIFTS NORTHEAST AND COLDER AIR ADVECTS
ACROSS THE AREA. EXPECT SNOW SHOWERS TO DECREASE IN COVERAGE AND
INTENSITY THROUGH THE NIGHT BUT STILL THE POTENTIAL FOR SOME
ADDITIONAL...THOUGH MINOR ACCUMULATION FRIDAY EVENING ESPECIALLY
ACROSS NORTHEAST IL INTO NORTHWEST INDIANA. WITH AT LEAST SOME
PARTIAL CLEARING IN ADDITION TO THE COLD AIR ADVECTION...EXPECT
TEMPS TO DIP INTO THE TEENS ACROSS NORTHWEST IL AND GIVEN THE
EXPECTED SNOWFALL TONIGHT...TEMPS COULD DROP EVEN FURTHER WITH
THE FRESH SNOWPACK.
THE WEEKEND IS LOOKING FAIRLY QUIET AS A LARGE RIDGE OF HIGH
PRESSURE BUILDS ACROSS THE REGION ON SATURDAY...SHIFTING EAST
SATURDAY NIGHT INTO SUNDAY. DESPITE SUNSHINE...AIRMASS REMAINS
FAIRLY COLD SATURDAY COMBINED WITH THE SNOWPACK...HIGHS MAY ONLY
REACH LOW/MID 30S. WITH LIGHT WINDS AND CLEAR SKIES...SHOULD SEE
A QUICK DROP IN TEMPS SATURDAY EVENING BUT WITH STRONG WARMING
ALOFT OVERNIGHT...TEMPS LIKELY TO BECOME STEADY OR EVEN BEGIN
RISING A FEW DEGREES OVERNIGHT INTO SUNDAY MORNING.
ANOTHER STORM SYSTEM THEN MOVES EAST ACROSS THE UPPER MIDWEST AND
NORTHERN LAKES SUNDAY AND SUNDAY NIGHT AND IT APPEARS THE BULK OF
THE PRECIP WITH THIS SYSTEM WILL REMAIN NORTH OF THE CWA BUT AS A
WEAK COLD FRONT MOVES ACROSS THE AREA SUNDAY NIGHT...THERE COULD BE
A PASSING SNOW OR RAIN SHOWER SUNDAY NIGHT AND HAVE MAINTAINED LOW
CHANCE POPS DURING THIS TIME. WITH STRONG WARMING CONTINUING SUNDAY
AHEAD OF THIS STORM SYSTEM...DEWPOINTS RECOVER INTO THE LOWER 30S
AND DESPITE THE SNOWPACK...TEMPS HAVE THE POTENTIAL TO WARM INTO
THE 40S...PERHAPS EVEN WARMER SOUTH OF WHEREVER THE MORE
SIGNIFICANT SNOW PACK ENDS UP FALLING OVER THE NEXT DAY.
THEN COMES NEXT WEEK AND THE POTENTIAL FOR ANOTHER SIMILAR STORM
TO THE ONE TO AFFECT THE AREA TONIGHT. MODELS DIFFER ON THE OVERALL
TIMING/PROGRESSION OF THIS STORM SYSTEM WITH THE ECMWF MUCH DEEPER
AND SLOWER WITH THE LOW NOT MOVING EAST ACROSS THE AREA UNTIL
WEDNESDAY AFTERNOON...WHICH IS MUCH SLOWER THAN THE WEAKER/FASTER
GFS. APPEARS LOW LEVELS WILL BE WARM ENOUGH TO SUPPORT ALL RAIN
UNTIL THE LOW MOVES EAST WHEN PRECIP COULD QUICKLY CHANGE TO SNOW
BEFORE ENDING. TOO FAR OUT IN TIME FOR SPECIFICS AND ALSO KEPT
MENTION OF RAIN OR SNOW OVER MUCH OF THE NORTHERN CWA. CMS
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 04Z...
* RAIN/DRIZZLE/GRAUPEL WILL CHANGE TO WET SNOW OVERNIGHT
* CIGS/VSBY LIKELY REMAIN IFR/LIFR THROUGH TONIGHT
* STEADY SNOW TAPERS OFF TO SCT`D SHSN BY MID MORNING FRIDAY
* CIGS/VSBYS TO STEADILY IMPROVE DURING THE DAY FRIDAY
* SHSN POSSIBLE AGAIN FRIDAY AFTERNOON
IZZI
//DISCUSSION...UPDATED 02Z...
SITUATION EVOLVING MORE SLOWLY THAN EARLIER ANTICIPATED AND HAVE
ONCE AGAIN DELAYED THE ONSET OF STEADIER SNOWFALL. RADAR/SATELLITE
TRENDS SHOW CONVECTIVEY ELEMENTS CONTINUING TO POP UP FROM CHGO
METRO SW TO UIN AREA...WITH REPORTS OF RA/SN/GS BEING RECEIVED
WITH THESE SHOWERS. UNTIL STEADIER HEAVIER DEFORMATION BAND
DEVELOPS OVER THE AREA AFTER MIDNIGHT...WOULD EXPECT TO CONTINUE
TO SEE OCNL SHRASNGS WITH PERIODIC DZ OUTSIDE OF THE SHOWERS.
STARTING TO SEE A MORE ORGANIZED FRONTOGENETIC BAND DEVELOP NEAR
THE QUAD CITIES INTO NW IL AND WOULD ANTICIPATE THIS BAND TO GROW
IN AREAL COVERAGE AND DEVELOP EAST TONIGHT...EVENTUALLY REACHING
CHICAGO METRO AREA AFTER MIDNIGHT. STILL ANTICIPATE A 4-6 HOUR
LONG PERIOD OF MODERATE TO HEAVY SNOW FOR CHICAGO...THOUGH NOW
APPEARS AS THOUGH THE MORE LIKELY TIMING IS LATE TONIGHT/EARLY
FRIDAY MORNING.
IZZI
UPDATED 00Z...
MOST CONCENTRATE BAND OF FRONTOGENETICALLY DRIVEN RAIN/WET SNOW
HAS SHIFTED NORTH OF THE TERMINALS INTO FAR SOUTHERN WISCONSIN
WITH POCKETS OF PRIMARILY RAIN REMAINING OVER NORTHERN IL. HEAVIER
BURSTS OF PRECIP EARLY THIS EVENING COULD RESULT IN RAIN MIXING
WITH OR CHANGING TO WET SNOW...HOWEVER WATER VAPOR IMAGERY SHOWS
THE UPPER LOW STILL DIGGING SOUTHEAST INTO WESTERN IOWA EARLY THIS
EVENING. SHOULD SEE FORCING FROM THIS UPPER LOW RESULT IN INCREASE
IN COVERAGE/INTENSITY OF PRECIPITATION OVER NORTHERN ILLINOIS AS
THE EVENING WEARS ON. SUSPECT COOLING REQUIRED TO CAUSE A CHANGE
OVER TO WET SNOW WILL BE DRIVEN LARGELY BY DYNAMIC COOLING/ASCENT
AS THE UPPER LOW APPROACHES...SO THIS MAKES TIMING SOMEWHAT
TRICKY. TRENDS IN SHORT RANGE MODELS AS WELL AS SATELLITE IMAGERY
TEND TO SUPPORT A SLOWER CHANGE OVER TO ALL SNOW AND HAVE DELAYED
THE SWITCH-OVER ANOTHER HOUR WITH THE LATEST SET OF TAFS.
ONCE BAND OF MODERATE TO HEAVY SNOW DEVELOPS WOULD ANTICIPATE
SEEING A A GOOD 4-6 HOUR LONG PERIOD OF MODERATE TO HEAVY SNOW AT
THE CHGO METRO TERMINALS FROM LATE THIS EVENING THROUGH MUCH OF
THE OVERNIGHT HOURS. SLOWER MOVEMENT OF THE UPPER LOW ALSO
SUPPORTS HANGING ONTO THE HEAVIER/ACCUMULATING SNOW LATER INTO THE
NIGHT/EARLY MORNING FRIDAY. HAVE CONTINUED WITH IFR VSBY SNOW
THROUGH 14Z...BUT ACTUALLY WORRIED THAT THE SNOW COULD BE HEAVIER
EVEN INTO THE FIRST PART OF THE DAY WHEN MORNING TRAFFIC PICKS UP.
HAVE MAINTAINED TEMPO FOR +TSSN IN THE TAFS AS OBSERVATIONAL DATA
AND SPC MESOANALYSIS DATA CONTINUE TO SUGGEST THE PRESENCE OF WEAK
INSTABILITY WHICH COMBINED WITH STRONG FORCING WOULD SEEM TO
SUPPORT THE THREAT OF EMBEDDED THUNDERSTORMS DEVELOPING OVERNIGHT.
STEADY SYSTEM SNOWS ARE LIKELY TO END EARLY/MID MORNING FRIDAY BUT
CYCLONIC LOW LEVEL FLOW...DEEP MOISTURE...AND EXCEPTIONALLY STEEP
LAPSE RATES WOULD SUPPORT THE CONTINUATION OF SNOW SHOWERS THROUGH
THE DAY FRIDAY. WHILE HAVE ONLY HAVE ONLY VFR SHSN IN THE TAFS FOR
NOW...POTENTIAL EXISTS FOR PERIODIC IFR VSBYS WITH ANY HEAVIER
SNOW SHOWERS FRIDAY AFTERNOON. WILL TAKE A CLOSER LOOK AT THIS
POTENTIAL WITH LATER TAF ISSUANCES.
IZZI
//ORD AND MDW CONFIDENCE...UPDATED 04Z...
* HIGH CONFIDENCE IN SWITCH OVER TO HEAVY WET SNOW...MEDIUM
CONFIDENCE ON TIMING
* LOW CONFIDENCE ON THUNDERSTORM POTENTIAL
* MEDIUM-HIGH CONFIDENCE ON ACCUMULATING SNOW LINGERING INTO EARLY
FRIDAY MORNING
* MEDIUM CONFIDENCE ON SHSN POTENTIAL FRIDAY AFTERNOON
IZZI
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 12Z...
SATURDAY...VFR.
SUNDAY...SLIGHT CHANCE OF SHOWERS...OTHERWISE VFR.
MONDAY...VFR.
TUESDAY...CHANCE FOR RAIN/SNOW...POSSIBLE MVFR.
WEDNESDAY...CHANCE FOR RAIN...POSSIBLE MVFR.
RODRIGUEZ
&&
.MARINE...
116 PM CST
AN ACTIVE WEATHER PATTERN IS IN STORE FOR THE NEXT SEVERAL DAYS.
LOW PRESSURE WILL DEEPEN AS IT MOVES FROM SOUTHERN MISSOURI THIS
AFTERNOON TO THE EASTERN LAKES FRIDAY AFTERNOON. WINDS WILL BACK
FROM EAST TO NORTHWEST AND STRENGTHEN OVER LAKE MICHIGAN. SOME
GALE FORCE GUSTS ARE POSSIBLE OVER SOUTHERN LAKE MICHIGAN FRIDAY
MORNING...BUT FEEL IT WILL BE A SHORT DURATION EVENT AND WILL HOLD
OFF ON GALE HEADLINES FOR NOW. WILL CONTINUE WITH SMALL CRAFT
ADVISORY FOR THE IL AND IN NEARSHORE AREA. A RIDGE OF HIGH
PRESSURE WILL MOVE ACROSS LAKE MICHIGAN SATURDAY NIGHT BEFORE
ANOTHER LOW PRESSURE APPROACHES SUNDAY AND SUNDAY NIGHT. THIS LOW
WILL TAKE A PATH FURTHER NORTH FROM THE NORTHERN PLAINS TO LAKE
SUPERIOR...GENERATING MODERATELY STRONG SOUTHWEST FLOW OVER LAKE
MICHIGAN. THE NEXT STORM SYSTEM WILL MOVE ACROSS IL AND IN AROUND
WEDNESDAY.
ALLSOPP
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ006-ILZ013-ILZ014-ILZ022 UNTIL 9 AM
FRIDAY.
WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ019-ILZ020 UNTIL 6 AM FRIDAY.
IN...WINTER WEATHER ADVISORY...INZ001-INZ002 UNTIL 9 AM FRIDAY.
LM...SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 4 PM FRIDAY.
SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 10 PM SATURDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
347 AM CST FRI FEB 24 2012
.SHORT TERM /TODAY/...
ACCUMULATING SNOW QUICKLY DIMINISHING AS SURFACE LOW CONTINUES TO
PULL EAST THIS MORNING. MAIN CONCERN TODAY IS WITH WINDS AND
POTENTIAL FOR SNOW SHOWERS. CAA WILL CONTINUE TO INCREASE THROUGHOUT
THE DAY WITH PRESSURE GRADIENT AND SOME MIXING. MIXING WILL BE
SOMEWHAT LIMITED TO THE STRATUS DECK HOLDING STRONG THROUGH THE DAY.
WINDS ATOP THE MIXED LAYER NEARING 40KTS BY LATE THIS
AFTERNOON...BUT THINKING THE RUC IS A LITTLE OVERDONE AND LEANED
TOWARD THE SREF/NAM FOR WINDS. THE 925-850MB RH PERSISTS TODAY AND
IS WELL WITHIN THE SNOW GROWTH ZONE...ESPECIALLY OVER THE EASTERN
AND NORTHERN SECTIONS OF THE FORECAST AREA. KEPT WITH MENTION OF
SNOW SHOWERS TODAY AND LIGHT ACCUMULATIONS...MAY SEE A HALF INCH
FROM THE ALO TO MCW AREA. NOT ANTICIPATING TEMPS TO RISE ALL THAT
MUCH TODAY WITH THE CAA...STRATUS DECK...AND FRESH SNOW PACK. SO
WENT SLIGHTLY BELOW GUIDANCE FOR MAX TEMPS TODAY.
.LONG TERM /TONIGHT THROUGH THURSDAY/...
TWO SIGNIFICANT SYSTEMS TO CONTEND WITH THROUGH THIS
PERIOD...PRECEDED BY VERY MINOR WAVE TONIGHT. THE LATTER IS
EXPECTED TO CROSS THE NRN ROCKIES INTO THE LOWER MO RIVER VALLEY BY
THIS AFTERNOON AND THIS EVENING. WAVE IS CURRENTLY GENERATING SOME
LIGHT SNOW OR FLURRIES ACROSS MT/ND SO HAVE ADDED TRACE WORDING SW
DURING THE EVENING TO ACCOUNT FOR THIS. MODEL REFLECTION OF THIS
SYSTEM QUITE VARIABLE WITH GEM REGIONAL AND GLOBAL MOST
AGGRESSIVE...WHILE THE ECMWF AND DOMESTIC MODELS ARE WEAKER. ANY
FORCING IS VERY COMPACT HOWEVER SO DAY SHIFT WILL HAVE TO EXAMINE
WHETHER STRENGTH IS SUFFICIENT TO WARRANT MEASURABLE MENTION AND IF
SO WHETHER IT CLIPS US OR STAYS JUST TO THE SOUTH AND WEST.
NEXT SYSTEM CURRENTLY OFF THE PACIFIC NW COAST WILL CROSS THE
ROCKIES SAT BEFORE AMPLIFYING AS IT ENTERS THE MID MO VALLEY.
FORCING...BOTH KINEMATIC AND THERMODYNAMIC...IS QUITE IMPRESSIVE
WITH THIS SYSTEM SAT NIGHT BUT MOISTURE BELOW 2.5KM IS SPARSE. BY
SUN AIRMASS REMAINS DRY WITH DOWNWARD MOTION QUICKLY SURGING IN
BEHIND SHARP QG FORCING COUPLET SO HAVE REMOVED NRN POPS ON SUN.
CONSIDERING THE STRENGTH OF THE LIFT SAT NIGHT THAT MAY BE A BETTER
POTENTIAL PRECIP WINDOW AND MAY NEED TO ADD TRACE AMOUNTS AT SOME
POINT IF MOISTURE CAN INCREASE SLIGHTLY.
NEXT SYSTEM WHICH IS EVEN STRONGER WITH SIMILAR BUT SLIGHTLY MORE
SOUTHERLY PATH WILL ENTER MO VALLEY LATE TUE. 00Z GFS/ECMWF ARE NOW
IN QUITE GOOD AGREEMENT TRACKING DEEP SURFACE LOW ACROSS NWRN IA TUE
EVENING. ALTHOUGH POTENT SNOW STORM MAY AFFECT DAKOTAS AND
MN...THIS PATH WILL KEEP IA MAINLY IN THE WARM SECTOR WHICH HAS
RESULTED IN WARMER TEMP FORECAST MON INTO TUE...ALONG WITH FURTHER
NUDGING UPWARD OF POPS. OVERALL FORCING WILL GRADUALLY INCREASE MON
NIGHT WITH SNOW POSSIBLE THEN INCREASE FURTHER TUE AND TUE NIGHT
WITH TRANSITION TO RAIN SHOWERS. HAVE ALSO ADDED ISOLATED THUNDER
CONSIDERING OVERALL STRENGTH OF LIFT ALONG WITH SHOWALTERS HOVERING
AROUND ZERO AND K INDICES WELL INTO THE 20S AND LOWER 30S. AS
SYSTEM PULLS AWAY WINDS WILL BECOME THE PRIMARY FEATURE FOR IA.
MODEL CONSENSUS SUGGESTS SUSTAINED SPEEDS ABOVE 20KTS SOUTH AND WEST
BY MIDDAY WED WITH GUSTS AT HIGH AS 35-40KTS.
&&
.AVIATION...24/06Z
HEAVY SNOW TAPERING OFF WITH LINGERING LIGHT SNOW EXPECTED FOR THE
REMAINDER OF THE OVERNIGHT HOURS AFFECTING ALL TAF SITES WITH THE
EXCEPTION OF KOTM...WHICH WILL STILL HAVE SOME HEAVY SNOW IN THE
FIRST FEW HOURS OF THE TAF PERIOD. OTHERWISE EXPECT CIGS TO LIFT TO
MVFR THROUGH THE PERIOD. COOLER TEMPERATURES ALOFT TO MOVE IN
ALLOWING FOR MIXING FRIDAY DURING THE DAY...AND STRONG NORTHWEST
WINDS ALOFT TO MIX TO THE SURFACE. THIS COULD ALSO ALLOW FOR SOME
SNOW SHOWERS TO DEVELOP ACROSS THE AREA FRIDAY AFTERNOON. WINDS
EXPECTED TO STAY UP FRIDAY NIGHT WITH MVFR/LOW VFR CIGS.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...KLP
LONG TERM...BSS
AVIATION...MJB
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
317 AM CST FRI FEB 24 2012
.SYNOPSIS...
06Z SFC ANALYSIS HAS A LOW NEAR KDNV WITH THE MAIN SYNOPTIC LOW
SOUTHEAST OF KCEZ BUT STILL WEST OF CINCINNATI. A SUGGESTED MESO LOW
WAS SOUTH OF KVYS BUT EAST OF KC75 ALONG THE ILLINOIS RIVER. AN
INVERTED TROF RAN NORTHWEST FROM THE MESO LOW INTO WESTERN WISCONSIN
WHILE A SECONDARY TROF RAN FROM THE LOW WEST INTO NORTHERN MISSOURI.
DEW POINTS WERE IN THE 20S AND 30S ACROSS MUCH OF THE MIDWEST WITH
40S AND HIGHER IN THE OHIO VALLEY AND DEEP SOUTH. RADAR TRENDS SHOW
THE DEFORMATION ZONE MOVING EAST ACROSS THE AREA.
&&
.SHORT TERM...TODAY AND TONIGHT...
THE IMMEDIATE CONCERN IS WHAT TO DO WITH CURRENT HEADLINES.
OVERALL...TRENDS FROM THE RUC ARE QUITE USEFUL IN DEPICTING THE
CURRENT WX. A COMBINATION OF THE HEAVY RAIN TOOL WITH OVERALL
FORCING/CONDENSATION PRESSURE DEFICITS INDICATES THAT SNOW WILL
STILL BE ONGOING ACROSS THE EASTERN CWFA AT 12Z IN THE DEFORMATION
ZONE. AS SUCH...THE CURRENT HEADLINES WILL BE EXTENDED FOR 1-2 HRS
FOR HENRY...WHITESIDE...BUREAU...AND PUTNAM COUNTIES IN ILLINOIS.
AFT 14Z...RUC TRENDS SHOW THE OVERALL FORCING FALLING APART WITH
CONDENSATION PRESSURE DEFICITS RISING A LITTLE. HOWEVER...THE
OVERALL ATMOSPHERE REMAINS SATURATED SO WHILE THE INTENSITY OF THE
SNOW WILL LET UP TO POSSIBLY ONLY FLURRIES...-SN SHOULD CONTINUE
DURING THE MORNING HOURS.
BY LATE MORNING AND CONTINUING INTO THE AFTERNOON LOW LEVEL LAPSE
RATES BECOME VERY STEEP. THE RUC ALONG WITH OTHER MODELS SHOW A
RESPECTABLE VORT MAX ROTATING THROUGH THE AREA WHICH SHOULD INDUCE
SHSN FROM LATE MORNING THROUGH THE AFTERNOON HOURS. THE STEEP LAPSE
RATES WILL ALSO ALLOW HIGHER MOMENTUM AIR TO MIX DOWN RESULTING IN
BRISK IF NOT WINDY CONDITIONS.
ADDITIONAL SNOW ACCUMULATIONS AFTER 12Z SHOULD BE GENERALLY ONE HALF
INCH OR LESS.
TONIGHT...LOW LEVEL LAPSE RATES REMAIN QUITE STEEP WITH NO
STABILIZATION OCCURRING UNTIL ROUGHLY SUNRISE. ADD INTO THIS
CHANNELED VORTICITY WITH SOME CYCLONIC FLOW ACROSS THE AREA AND
CLOUDS MAY BE SLOW TO BREAK UP OR CLEAR OUT. THEREFORE...WILL HOLD
ONTO THE CLOUDS LONGER. ADDITIONALLY...SINCE SUNSET IS NOW CLOSER TO
6 PM THERE MAY BE SOME LINGERING FLURRIES OR DECAYING SHSN INTO THE
EARLY EVENING ACROSS THE EASTERN CWFA.
..08..
.LONG TERM...
AN ACTIVE WEATHER REGIME WILL BE IN PLACE THROUGH THE LONG TERM
FORECAST. MODELS ARE IN AGREEMENT WITH A POTENT S/W PASSING TO OUR
NORTH LATE IN THE WEEKEND WITH A SIGNIFICANT TROF MOVING THROUGH
MID-WEEK.
FOR SATURDAY AND SATURDAY NIGHT...A HIGH PRESSURE RIDGE WILL BE OVER
THE AREA EARLY SATURDAY. THE RIDGE IS PUSHED EAST BY SATURDAY
EVENING AS S/W ENERGY MOVES OUT OF THE PAC NW INTO THE NORTHERN
PLAINS...DRIVING A SURFACE LOW INTO THE EASTERN DAKOTAS BY SUNDAY
MORNING. EXPECT DRY CONDITIONS DURING THE PERIOD SO TEMPERATURES
WILL BE THE MAIN CONCERN. LIMITED MIXING IN THE RIDGE AXIS
SATURDAY WILL LIMIT HIGHS. THERE MAY ALSO BE SOME RESIDUAL SNOW
COVER NORTH FROM THE CURRENT EVENT...SO WILL KEEP HIGHS IN THE
30S. MINS SATURDAY NIGHT WILL LIKELY OCCUR DURING THE EVENING AS
SOUTHERLY FLOW BEGINS INCREASING AHEAD OF THE NORTHERN PLAINS
SURFACE LOW. KEPT MINS AROUND 20 IN THE NORTHEAST WHERE BEST
COOLING POTENTIAL EXISTS WITH LIGHT WINDS IN THE EVENING AND
POSSIBLY SOME SNOW STILL ON THE GROUND. LOWS IN THE SOUTHWEST
SHOULD OCCUR FAIRLY EARLY IN THE EVENING...SO KEPT THAT AREA IN THE
LOW 30S. TEMPS SHOULD STEADY OUT OR RISE SOME DURING THE LATE
EVENING AND OVERNIGHT HOURS.
SUNDAY AND SUNDAY NIGHT THE NORTHERN PLAINS S/W AND SURFACE LOW
WILL CROSS MN AND MOVE INTO THE GREAT LAKES BY MONDAY MORNING. A
COLD FRONT BEHIND THE SYSTEM WILL DROP SOUTHEAST THROUGH THE
FORECAST AREA SUNDAY NIGHT. WITH LIMITED MOISTURE AND THE BEST
FORCING STAYING WELL NORTH OF THE CWFA...HAVE REMOVED THE LOW POPS
FROM THE NORTH. HIGHS IN THE 40S NORTH TO MID 50S FAR SOUTH LOOK
REASONABLE WITH THE FORECAST AREA IN THE WARM SECTOR SUNDAY...AND
GUSTY SOUTHWEST WINDS TO AID DEEP MIXING. THE COLD FRONT WILL MOVE
THROUGH SUNDAY NIGHT...BUT THE AIR BEHIND THE FRONT IS NOT THAT
COLD...SO KEPT MINS IN THE MID 20S TO LOW 30S.
THE NEXT SYSTEM TO IMPACT THE AREA IS A SIGNIFICANT TROF THAT IS
EXPECTED TO MOVE INTO THE CA COAST MONDAY AND HEAD EAST INTO THE
PLAINS BY TUESDAY EVENING. THE MODELS WERE COMING INTO DECENT
AGREEMENT ON THE 24/00Z RUN WITH THIS SYSTEM TAKING A MORE
NORTHERN TRACK...LIFTING THE SURFACE LOW THROUGH NW IA TUESDAY
NIGHT AND INTO THE GREAT LAKES BY LATE WEDNESDAY. WITH GOOD
AGREEMENT AMONG THE LONG RANGE MODELS THE BLENDED GUIDANCE HAS
WARMED TEMPERATURES UP CONSIDERABLY MONDAY NIGHT THROUGH
WEDNESDAY. HAVE EVEN BUMPED UP TEMPERATURES A FEW DEGREES FROM
GUIDANCE MONDAY NIGHT AND TUESDAY WHEN IT APPEARS WE WILL BE IN
THE WARM SECTOR. THE SYSTEM SHOULD HAVE SOME GULF MOISTURE TO WORK
WITH AS IT MOVES THROUGH THE MID MS VALLEY SO MAINTAINED HIGH
CHANCE OR LIKELY POPS TUESDAY INTO WEDNESDAY. SOME THUNDERSTORMS
CANNOT BE RULED OUT FOR TUESDAY NIGHT WHEN THE BEST FORCING WILL
LIFT THROUGH THE AREA. HOWEVER...I DID NOT MENTION ANY THUNDER
YET...SINCE THERE IS STILL POTENTIAL FOR THE MODEL SOLUTIONS TO
VARY. STRONG WEST TO NORTHWEST WINDS WILL USHER IN COLDER AIR LATE
TUESDAY NIGHT AND WEDNESDAY AS THE OCCLUDED SYSTEM LIFTS NORTHEAST
THROUGH WI AND INTO THE GREAT LAKES. WITH THE COLD AIR MOVING BACK
IN ANY LINGERING PRECIP WILL MIX WITH OR CHANGE TO SNOW. BY
THURSDAY TEMPERATURES SHOULD BE BACK TO NEAR NORMAL. ..DLF..
&&
.AVIATION... /ISSUED 1130 PM CST THU FEB 23 2012/
MODERATE SNOW WILL PERSIST AT AREA TERMINALS AND PRODUCE IFR
CONDITIONS DURING THE NEXT SEVERAL HOURS. AS THE SURFACE LOW AND
UPPER LEVEL TROUGH SHIFT EAST...SNOW WILL START ENDING AFTER
SUNRISE...AND VFR CONDITIONS SHOULD DEVELOP AT ALL TERMINALS BY
LATE MORNING. WINDS WILL INCREASE THROUGH THE PERIOD...SHIFTING
FROM NORTH TO NORTHWEST AND GUSTING UP TO AROUND 25 KTS. WOLF
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR
BENTON-BUCHANAN-CEDAR-CLINTON-DELAWARE-DUBUQUE-IOWA-JACKSON-
JOHNSON-JONES-LINN-MUSCATINE-SCOTT.
IL...WINTER WEATHER ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR
CARROLL-JO DAVIESS-ROCK ISLAND-STEPHENSON.
WINTER WEATHER ADVISORY UNTIL 8 AM CST THIS MORNING FOR BUREAU-
PUTNAM.
WINTER WEATHER ADVISORY UNTIL 7 AM CST THIS MORNING FOR HENRY IL-
WHITESIDE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
349 AM CST FRI FEB 24 2012
.DISCUSSION...
UPPER LEVEL JET REMAINS ON THE STRONG SIDE...RESIDING FROM THE
PACIFIC NORTHWEST SOUTHEAST INTO THE SOUTHERN ROCKIES THEN EAST-
NORTHEAST INTO THE OHIO VALLEY. WATER VAPOR IMAGERY IS SHOWING A
MORE PROGRESSIVE PATTERN TAKING SHAPE IN THE EASTERN PACIFIC
OCEAN. SURFACE PRESSURE GRADIENT CONTINUES TO RELAX WITH
YESTERDAYS WIND-MAKER ALREADY INTO THE UPPER OHIO VALLEY.
SCATTERED LOWER CLOUDS CONTINUE TO MAKE SOUTHEAST PROGRESS THROUGH
THE NORTHERN AND CENTRAL PLAINS...WITH SOME DEEPER CLOUD NOTED IN
EASTERN MONTANA AND THE WESTERN DAKOTAS.
MODELS QUITE SIMILAR WITH THE WEAK WAVE UPSTREAM OF THIS MORNINGS
ENHANCED CLOUDS REACHING CENTRAL PORTIONS OF NEBRASKA AND KANSAS
LATE THIS AFTERNOON. MID LEVEL FRONTOGENESIS RESULTS IN EASTERN
NEBRASKA...WITH FAR NORTHERN KANSAS ALONG ITS WARM SIDE. MAY SEE
SCATTERED HIGH-BASED PRECIP REACH THE NORTHERN COUNTIES BY MID
AFTERNOON...BUT PERSISTENCE AND COVERAGE SHOULD LIMIT ANY
ACCUMULATIONS TO TRACE AMOUNTS. FORCING DIMINISHES BY LATE EVENING
WITH CLEARING TAKING PLACE. SOME OTHER HIGH-BASED CU MAY DEVELOP
THIS AFTERNOON AS MIXING HEIGHTS ARE AGAIN ADVERTISED TO BE RATHER
HIGH UNDER THE -36C 500MB TEMPS. WILL AGAIN GO WITH SOME HIGHER
GUSTS FOR THE AFTERNOON HOURS...BUT EXTREME GUSTS SEEM RATHER
UNLIKELY GIVEN 50KT SPEEDS RESIDE ABOVE 600MB. WEAK WINDS IN QUICKLY
RISING UPPER HEIGHTS SHOULD ALLOW FOR LOWS IN THE LOWER TO MIDDLE
20S.
NEXT SYSTEM LATE SATURDAY INTO SUNDAY STILL ON TRACK TO STAY WELL
NORTH OF THE AREA...BUT STILL BRING A MODIFIED PACIFIC FRONT THROUGH
LATE SATURDAY NIGHT. STRONG WINDS WILL DEVELOP AS THIS SYSTEM
PASSES...AND COULD NEAR ADVISORY LEVELS SATURDAY AFTERNOON IN THE
WEST...AND PERHAPS IN THE LATE EVENING TO EARLY MORNING HOURS
SATURDAY NIGHT BEFORE FRONTAL PASSAGE. HIGHS SHOULD STILL REACH THE
UPPER 40S TO UPPER 50S BOTH WEEKEND DAYS.
MODELS CONTINUE TO COME INTO BETTER AGREEMENT WITH THE NEXT TROF. A
FARTHER SOUTH TRACK SHOULD TAKE PLACE...WITH THE WEEKEND FRONT NOT
CLEARING THE GULF AND ALLOWING FOR BETTER MOISTURE RETURN. RAIN
CHANCES APPEAR BY LATE MONDAY IN INCREASING WARM AIR
ADVECTION...WITH BEST CHANCES MONDAY NIGHT INTO TUESDAY WITH
CONVECTION QUITE POSSIBLE BY LATE TUESDAY WITH THE FRONTS PASSAGE.
HAVE INCREASED TEMPS QUITE A BIT FOR THESE PERIODS AS MODELS
CONVERGE....THOUGH UNCERTAINTY STILL SOMEWHAT HIGH WITH ONSET AND
CLEARING OF LOW LEVEL MOISTURE AND CLOUDS A MAIN PLAYER.
65
&&
.AVIATION...
THE MVFR STRATUS HAS MOVED SOUTH ALONG THE MO RIVER...HOWEVER IT
DOES NOT APPEAR TO BE AS FAR WEST AS THE 00Z NAM THINKS IT SHOULD
BE. THE 03Z RUC STILL GRAZES TOP AND FOE WITH THE HIGHER 925 RH. SO
WILL KEEP A TEMPO MVFR CIG THINKING THERE IS STILL A REASONABLE
POTENTIAL FOR THE LOWER CIGS. THESE CLOUDS SHOULD BE EAST OF THE
TERMINALS BY SUNRISE FRIDAY. DEEP MIXING OF THE BOUNDARY LAYER
SHOULD LEAD TO GUSTY WINDS DURING THE DAY FRIDAY.
WOLTERS
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1100 PM CST THU FEB 23 2012
...AVIATION UPDATE...
.DISCUSSION...
SEE PREV DISCUSSION.
&&
.AVIATION...
THE MVFR STRATUS HAS MOVED SOUTH ALONG THE MO RIVER...HOWEVER IT
DOES NOT APPEAR TO BE AS FAR WEST AS THE 00Z NAM THINKS IT SHOULD
BE. THE 03Z RUC STILL GRAZES TOP AND FOE WITH THE HIGHER 925 RH. SO
WILL KEEP A TEMPO MVFR CIG THINKING THERE IS STILL A REASONABLE
POTENTIAL FOR THE LOWER CIGS. THESE CLOUDS SHOULD BE EAST OF THE
TERMINALS BY SUNRISE FRIDAY. DEEP MIXING OF THE BOUNDARY LAYER
SHOULD LEAD TO GUSTY WINDS DURING THE DAY FRIDAY.
WOLTERS
&&
.PREV DISCUSSION... /307 PM CST THU FEB 23 2012/
THURSDAY EVENING THROUGH FRIDAY...SECONDARY PRESSURE SURGE AND
SUBSIDENCE WILL PRODUCE THE STRONGEST WINDS ACROSS THE AREA THROUGH
THE EVENING HOURS WITH GUSTS AROUND 50 MPH EXPECTED. UPPER LOW NOW
ACROSS EASTERN NEBRASKA WILL PIVOT SE OVERNIGHT WITH SOME STRATUS
EXPECTED TO DROP INTO THE NORTHERN CWA OVERNIGHT BUT PRECIP SHOULD
BE LIMITED TO AREAS NEAR THE NEBRASKA BORDER OR NORTHWARD.
ANOTHER WINDY AND COOLER DAY IS EXPECTED FRIDAY WITH HIGHS IN THE
MID TO UPPER 40S EXPECTED AS ANY STRATUS SHOULD SCATTER OUT BY
AFTERNOON.
FRIDAY EVENING THROUGH THURSDAY...STRONG WINDS CHARACTERIZE THE
UPCOMING WEEKEND AS THE NEXT DEEPENING SURFACE TROF TRACKS ACROSS
WESTERN KANSAS. THE SYSTEM WILL PASS THROUGH DRY AS A STRENGTHENING
PRESSURE GRADIENT WILL INCREASE WIND SPEEDS SATURDAY AFTERNOON
THROUGH SUNDAY. IN ADDITION...WELL MIXED PROFILER SOUNDINGS SUGGEST
HIGHS TO BE IN THE LOWER 50S SATURDAY INTO THE UPPER 50S SUNDAY.
AS THE AFOREMENTIONED UPPER TROUGH LIFTS NORTHEAST ANOTHER
PROGRESSIVE NEGATIVELY TILTED TROUGH BUILDS OVER THE WESTERN
CONUS MONDAY INTO TUESDAY. THE CLOSED SURFACE LOW IS SHOWN TO DEEPEN
AS IT LIFTS NORTHEAST ACROSS THE CENTRAL PLAINS. AMPLE MOISTURE
PROVIDED FROM THE GULF WILL DEVELOP DECENT CHANCES FOR RAIN OR
SNOW OVER THE CWA. WHILE THE 12Z ECMWF IS FASTER THAN THE 12Z
GFS...BOTH MODELS SEEM TO BE FAIRLY AGGRESSIVE IN THE STRENGTH OF
THE SYSTEM AND THE DECENT QPF AMOUNTS. AT THIS TIME...SIDED MORE
WITH THE ECMWF WHICH PLACES AREAS SOUTH OF INTERSTATE 70 IN THE
UNSTABLE WARM SECTOR WITH MUCAPES VALUES NEAR 300 J/KG AND 60 KTS
OF 0-6 KM SHEAR. DECIDED TO INCLUDE ISOLATED THUNDER TUESDAY
AFTERNOON INTO THE EVENING HOURS FOR THESE PARTICULAR AREAS WHILE
NORTH OF INTERSTATE 70 IS DEPICTING A MIXTURE OF LIGHT RAIN OR
LIGHT SNOW. BY TUESDAY EVENING...COLDER AIR WRAPPING ON THE
BACKSIDE OF THE LOW SHOULD TRANSITION ALL PRECIP TO LIGHT SNOW
BEFORE THE SYSTEM EXITS WEDNESDAY MORNING. VARIABILITY IN TIMING
AND TRACK OF THIS SYSTEM BETWEEN THE MODELS IS LARGE AND YET TO BE
RESOLVED THIS MANY DAYS OUT.
BOWEN
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 9 PM CST THIS EVENING FOR KSZ011-012-024-026-
038>040-054>056-058-059.
WIND ADVISORY UNTIL 6 PM CST THIS EVENING FOR KSZ008>010-020>023-
034>037.
&&
$$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1241 AM EST FRI FEB 24 2012
.Update...
Issued at 1241 AM EST Feb 24 2012
Upped PoPs to 100% where it is currently raining in the Blue Grass.
Moved the showers and storms out of the CWA around 09Z with dry
conditions from then through sunrise.
Issued at 1019 PM EST Feb 23 2012
Going to need to update the forecast quickly as convection is on the
rebound across our western sections. It appears that nocturnal
cooling is quickly eroding the elevated mix/warm layer and
convection is now being able to develop vertically with the
reduction in convective inhibition. Recent radar imagery reveals
showers and thunderstorms quickly developing west of I-65...but
still well out ahead of the surface frontal boundary. Storms do not
appear to be rooted in the surface layer...yet. Main threats look
to be gusty winds and possibly some large hail.
Updated products out shortly.
Update issued at 938 PM EST Feb 23 2012
Convection continues to rumble across our eastern sections this
evening. Parameters never really got in sync with each other to
produce a severe weather. We did have one decent storm that popped
across Bullitt county that produced a decent amount of dime sized
hail. Those storms have quickly moved to the northeast and are close
to exiting our Bluegrass counties. Other convection continues to
struggle across the eastern portions of south-central Kentucky.
Convection appears to be driven in large part by large scale ascent
ahead of an approaching trough axis. 00Z BNA sounding showed a very
deep mixed layer in the lower levels with some instability aloft.
Much of the activity across south-central KY appears to be elevated
as well.
Surface front is now pushing into western Kentucky. Some
development has recently popped up across northwest Tennessee near
Clarksville. Will be watching this activity as it is closer to the
better moisture and may eventually become rooted near the surface.
This activity...if it holds together would affect our far southern
counties over the next few hours. For now...have kept slight-chance
PoPs in the west with the highest PoPs in the east for the next few
hours. If convection to our southwest holds together, will need to
raise PoPs a bit more in the south. Overall threat of severe
weather looks greatly diminished...however any storm will be capable
of producing heavy rains, gusty winds, small hail, and cloud to
ground lightning.
Updated forecast and text products are already out.
Update issued at 635 PM EST Feb 23 2012
Did a quick update to the forecast to account for the batch of
convection that fired up east of I-65 and will affect the Bluegrass
region early this evening. Elsewhere, lowered PoPs slightly for the
next few hours and then ramped them back up as the frontal boundary
to the west swings through the region.
It appears that we`re in a waiting game this evening with regards to
the severe weather threat. Initial batch of convection fired just
west of I-65 late this afternoon. However, strong moisture
convergence and theta-e advection appears to have spawn the
convective cluster that is currently moving through the Bluegrass
region.
Looking at the mesoscale analysis...it appears that several
variables are present which are limiting our convective potential at
the present time. First...the strong mid-level westerly flow has
prevent moisture transport northward from the south. While the
models indicated that mid-50s dewpoints would advect north...that
has not happened...yet. Secondly, ACARS soundings out of SDF this
afternoon reveal an elevated mixed layer which has led to increasing
values of convective inhibition...generally across the south and
western sections of the forecast area. Convection across the
Bluegrass is not rooted at the surface...but appears to be elevated
in nature. The strong westerly flow has also resulted in bulk shear
values of over 70kts. Vertical and 3-D analysis of the radar data
with the initial storms indicated that the shear was tilting the
updrafts quite a bit to the NE with increasing height.
While it appears that we may be entering a relative minimum in
convective coverage, recent observations do show moisture pooling
out ahead of the surface cold frontal boundary which is still west
of the Wabash and Mississippi Rivers. Quality moisture is still
lacking, but dewpoints are getting into the mid 50s. With the onset
of nocturnal cooling...I believe that this elevated mixed/warm layer
will likely mix out. This perhaps may be already occurring to the
west as inhibition is weakening quickly to the west and CAPE values
have increased a bit according to the latest SPC mesoanalysis.
I believe that we still have a window of opportunity for convection
this evening as the front pushes into the region. The HRRR and
other high resolution models appear to have backed off convection
slightly. However, these models have a history of being a bit too
pessimistic with convection in the past. The other thing we have
noted is that the surface winds have started to shift back to
southwest in areas to our west. This will likely result in a
lowering of storm-relative helicity and may result in a lesser
threat for updrafts to obtain or sustain rotation. Will continue to
monitor things closely over the next couple of hours and amend the
forecast as required.
.Short Term (Tonight through Friday night)...
Updated at 300 PM EST Feb 23 2012
...Severe Weather Possible Through This Evening...
As of 20Z, a 990 mb surface low was over central Missouri, and its
associated warm front extended eastward across Kentucky. Starting
to see more of a cloud band coinciding with the east-west pressure
trough and wind shift. A fairly extensive cu field centered on the
confluence of the Wabash and Ohio Rivers seems to be the most likely
point to initiate severe convection in the next few hours.
SPC continues to advertise a slight risk, with a better than 30%
chance for severe wind gusts centered on the Ohio River. Tornado
probabilities have been lowered, but there is still concern
especially north of the boundary, where helicity is enhanced due to
the SE surface winds.
Temperatures have warmed sufficiently even north of the boundary
that the instability is there. However the low-level moisture return
has been slower to arrive, so we will have only a narrow window to
initiate storms late this afternoon. Worst weather is still expected
from roughly 22Z through 03Z, and at this point it is largely a
waiting game for convective initiation. Damaging winds, large hail,
and isolated tornadoes are all still in play.
Cold pool associated with the upper trof and low-level cold
advection will make for a chilly and raw Friday. Will maintain a low
overcast, with the chance for light rain especially in the northern
counties. POPs will range from a dry forecast south of the
Parkways...to a low-end chance in southern Indiana, and QPF will be
quite low. Tight pressure gradient behind the exiting low, and
efficient mixing will keep sustained winds at 15-25 mph with a few
gusts over 35 mph. Expect a very minimal recovery in temps, with
highs barely cracking 50 in the south. Lows Friday night will dip
into the upper 20s, which is actually just a couple degrees below
normal for this time of year. Expect a few flurries late in the
evening as the cold air finally arrives, but not looking for any
snow accumulation at all and will not mention a measurable POP.
.Long Term (Saturday through Thursday)...
Updated at 300 PM EST Feb 23 2012
Sat/Sun/Mon we`ll sit in a quiet weather period with temperatures
steadily increasing each day. Sfc high pressure will be in control
Sat/Sun with return flow beginning on Monday. Zonal flow aloft will
dominate Sat-Mon. While high temps will only be in the lower 40s
Sat, they should increase to the 50s for Sun/Mon. Low temps will be
in the mid 20s Sat night, but mid to upper 30s for Sun/Mon nights.
By Mon night, a strong upper level trough will drop south into the
Rockies creating lee side sfc cyclogenesis sometime early next
week. Models vary on the timing and sfc low/front evolution, but
generally it looks like the upper trough will push east into the
Midwest by Wed/Thurs with a sfc low pushing through the upper
Midwest. Ahead of this system, isentropic lift and very subtle
upper level waves passing through the region will begin Monday night
allowing for a 20% chance of rain showers over south central KY.
Lift and moisture return will continue to increase Tues combined
with weak upper level waves justifying an increase in POPs over the
entire area. Tues night or early Wed, the cold front or a warm
front and cold front (depending on which model soln you buy) will
cross the region causing showers and thunderstorms. There is still
quite a bit of discrepancy in the model sfc feature solns and so did
not make big changes to this forecast. As previously mentioned,
high temps for Tues/Wed will likely be warmer than what`s currently
in the forecast especially if we get a good warm surge ahead the
cold front. Will continue mid 50s to around 60 for highs Tues/Wed
until more certainty can be achieved.
Wed night/Thurs, precip should move east of the area with sfc high
pressure settling in again. High temps will cool back into the mid
40s to around 50.
&&
.Aviation (06Z TAF Issuance)...
Updated at 1205 AM EST Feb 24 2012
Low pressure over Louisville will head off into Ohio over the next
several hours, dragging its cold front through LEX around 09Z.
Widespread storms, some severe, developed across the region earlier
this evening but SDF and BWG are already in the clear, and LEX
should be done with their storms in the 06-0630Z time frame. Winds
will be from the west behind the front at speeds around 10kt.
With VFR conditions expected, winds will be the main issue for
aviation. West winds will become strong and gusty by morning, and
will remain that way through the daylight hours today. Gusts to 30
knots can be expected, with SDF likely receiving the worst winds.
Though some patchy light rain is possible today, the models have
trended quite a bit drier so will keep TAFs dry.
One mention on ceilings...we will go with VFR cigs for now, but
models do suggest a sub-VFR ceiling may be possible during the
07Z-13Z time frame, so we will have to keep an eye on that.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Updates..........MJ/13
Short Term.......RAS
Long Term........AMS
Aviation.........13
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1212 AM EST FRI FEB 24 2012
.Update...
Issued at 1019 PM EST Feb 23 2012
Going to need to update the forecast quickly as convection is on the
rebound across our western sections. It appears that nocturnal
cooling is quickly eroding the elevated mix/warm layer and
convection is now being able to develop vertically with the
reduction in convective inhibition. Recent radar imagery reveals
showers and thunderstorms quickly developing west of I-65...but
still well out ahead of the surface frontal boundary. Storms do not
appear to be rooted in the surface layer...yet. Main threats look
to be gusty winds and possibly some large hail.
Updated products out shortly.
Update issued at 938 PM EST Feb 23 2012
Convection continues to rumble across our eastern sections this
evening. Parameters never really got in sync with each other to
produce a severe weather. We did have one decent storm that popped
across Bullitt county that produced a decent amount of dime sized
hail. Those storms have quickly moved to the northeast and are close
to exiting our Bluegrass counties. Other convection continues to
struggle across the eastern portions of south-central Kentucky.
Convection appears to be driven in large part by large scale ascent
ahead of an approaching trough axis. 00Z BNA sounding showed a very
deep mixed layer in the lower levels with some instability aloft.
Much of the activity across south-central KY appears to be elevated
as well.
Surface front is now pushing into western Kentucky. Some
development has recently popped up across northwest Tennessee near
Clarksville. Will be watching this activity as it is closer to the
better moisture and may eventually become rooted near the surface.
This activity...if it holds together would affect our far southern
counties over the next few hours. For now...have kept slight-chance
PoPs in the west with the highest PoPs in the east for the next few
hours. If convection to our southwest holds together, will need to
raise PoPs a bit more in the south. Overall threat of severe
weather looks greatly diminished...however any storm will be capable
of producing heavy rains, gusty winds, small hail, and cloud to
ground lightning.
Updated forecast and text products are already out.
Update issued at 635 PM EST Feb 23 2012
Did a quick update to the forecast to account for the batch of
convection that fired up east of I-65 and will affect the Bluegrass
region early this evening. Elsewhere, lowered PoPs slightly for the
next few hours and then ramped them back up as the frontal boundary
to the west swings through the region.
It appears that we`re in a waiting game this evening with regards to
the severe weather threat. Initial batch of convection fired just
west of I-65 late this afternoon. However, strong moisture
convergence and theta-e advection appears to have spawn the
convective cluster that is currently moving through the Bluegrass
region.
Looking at the mesoscale analysis...it appears that several
variables are present which are limiting our convective potential at
the present time. First...the strong mid-level westerly flow has
prevent moisture transport northward from the south. While the
models indicated that mid-50s dewpoints would advect north...that
has not happened...yet. Secondly, ACARS soundings out of SDF this
afternoon reveal an elevated mixed layer which has led to increasing
values of convective inhibition...generally across the south and
western sections of the forecast area. Convection across the
Bluegrass is not rooted at the surface...but appears to be elevated
in nature. The strong westerly flow has also resulted in bulk shear
values of over 70kts. Vertical and 3-D analysis of the radar data
with the initial storms indicated that the shear was tilting the
updrafts quite a bit to the NE with increasing height.
While it appears that we may be entering a relative minimum in
convective coverage, recent observations do show moisture pooling
out ahead of the surface cold frontal boundary which is still west
of the Wabash and Mississippi Rivers. Quality moisture is still
lacking, but dewpoints are getting into the mid 50s. With the onset
of nocturnal cooling...I believe that this elevated mixed/warm layer
will likely mix out. This perhaps may be already occurring to the
west as inhibition is weakening quickly to the west and CAPE values
have increased a bit according to the latest SPC mesoanalysis.
I believe that we still have a window of opportunity for convection
this evening as the front pushes into the region. The HRRR and
other high resolution models appear to have backed off convection
slightly. However, these models have a history of being a bit too
pessimistic with convection in the past. The other thing we have
noted is that the surface winds have started to shift back to
southwest in areas to our west. This will likely result in a
lowering of storm-relative helicity and may result in a lesser
threat for updrafts to obtain or sustain rotation. Will continue to
monitor things closely over the next couple of hours and amend the
forecast as required.
.Short Term (Tonight through Friday night)...
Updated at 300 PM EST Feb 23 2012
...Severe Weather Possible Through This Evening...
As of 20Z, a 990 mb surface low was over central Missouri, and its
associated warm front extended eastward across Kentucky. Starting
to see more of a cloud band coinciding with the east-west pressure
trough and wind shift. A fairly extensive cu field centered on the
confluence of the Wabash and Ohio Rivers seems to be the most likely
point to initiate severe convection in the next few hours.
SPC continues to advertise a slight risk, with a better than 30%
chance for severe wind gusts centered on the Ohio River. Tornado
probabilities have been lowered, but there is still concern
especially north of the boundary, where helicity is enhanced due to
the SE surface winds.
Temperatures have warmed sufficiently even north of the boundary
that the instability is there. However the low-level moisture return
has been slower to arrive, so we will have only a narrow window to
initiate storms late this afternoon. Worst weather is still expected
from roughly 22Z through 03Z, and at this point it is largely a
waiting game for convective initiation. Damaging winds, large hail,
and isolated tornadoes are all still in play.
Cold pool associated with the upper trof and low-level cold
advection will make for a chilly and raw Friday. Will maintain a low
overcast, with the chance for light rain especially in the northern
counties. POPs will range from a dry forecast south of the
Parkways...to a low-end chance in southern Indiana, and QPF will be
quite low. Tight pressure gradient behind the exiting low, and
efficient mixing will keep sustained winds at 15-25 mph with a few
gusts over 35 mph. Expect a very minimal recovery in temps, with
highs barely cracking 50 in the south. Lows Friday night will dip
into the upper 20s, which is actually just a couple degrees below
normal for this time of year. Expect a few flurries late in the
evening as the cold air finally arrives, but not looking for any
snow accumulation at all and will not mention a measurable POP.
.Long Term (Saturday through Thursday)...
Updated at 300 PM EST Feb 23 2012
Sat/Sun/Mon we`ll sit in a quiet weather period with temperatures
steadily increasing each day. Sfc high pressure will be in control
Sat/Sun with return flow beginning on Monday. Zonal flow aloft will
dominate Sat-Mon. While high temps will only be in the lower 40s
Sat, they should increase to the 50s for Sun/Mon. Low temps will be
in the mid 20s Sat night, but mid to upper 30s for Sun/Mon nights.
By Mon night, a strong upper level trough will drop south into the
Rockies creating lee side sfc cyclogenesis sometime early next
week. Models vary on the timing and sfc low/front evolution, but
generally it looks like the upper trough will push east into the
Midwest by Wed/Thurs with a sfc low pushing through the upper
Midwest. Ahead of this system, isentropic lift and very subtle
upper level waves passing through the region will begin Monday night
allowing for a 20% chance of rain showers over south central KY.
Lift and moisture return will continue to increase Tues combined
with weak upper level waves justifying an increase in POPs over the
entire area. Tues night or early Wed, the cold front or a warm
front and cold front (depending on which model soln you buy) will
cross the region causing showers and thunderstorms. There is still
quite a bit of discrepancy in the model sfc feature solns and so did
not make big changes to this forecast. As previously mentioned,
high temps for Tues/Wed will likely be warmer than what`s currently
in the forecast especially if we get a good warm surge ahead the
cold front. Will continue mid 50s to around 60 for highs Tues/Wed
until more certainty can be achieved.
Wed night/Thurs, precip should move east of the area with sfc high
pressure settling in again. High temps will cool back into the mid
40s to around 50.
&&
.Aviation (06Z TAF Issuance)...
Updated at 1212 AM EST Feb 24 2012
Low pressure over Louisville will head off into Ohio over the next
several hours, dragging its cold front through LEX around 09Z.
Widespread storms, some severe, developed across the region earlier
this evening but SDF and BWG are already in the clear, and LEX
should be done with their storms in the 06-0630Z time frame. Winds
will be from the west behind the front at speeds around 10kt.
With VFR conditions expected, winds will be the main issue for
aviation. West winds will become strong and gusty by morning, and
will remain that way through the daylight hours today. Gusts to 30
knots can be expected, with SDF likely receiving the worst winds.
Though some patchy light rain is possible today, the models have
trended quite a bit drier so will keep TAFs dry.
One mention on ceilings...we will go with VFR cigs for now, but
models do suggest a sub-VFR ceiling may be possible during the
07Z-13Z time frame, so we will have to keep an eye on that.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........MJ
Short Term.......RAS
Long Term........AMS
Aviation.........13
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
222 AM EST FRI FEB 24 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE FROM KENTUCKY EARLY TODAY TO LAKE ERIE
THIS AFTERNOON WITH RAIN SHOWERS EARLY CHANGING TO SNOW SHOWERS
THIS EVENING. IT WILL TURN VERY WINDY AND MUCH COLDER BEHIND A
STRONG COLD FRONT THIS AFTERNOON WITH BLUSTERY AND COLD CONDITIONS
SATURDAY.
&&
.NEAR TERM /THROUGH TODAY/...
AN OVERNIGHT UPDATE HAS BEEN ISSUED TO LOWER POPS THROUGH DAWN AND
KEEP CHC THUNDER ACROSS NORTH-CENTRAL WV AND RIDGES OF MD/WV.
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES A 500MB TROUGH AXIS
CENTERED ACROSS IOWA WITH THE UPPER OHIO VALLEY IN A SOUTHWESTERLY
FLOW AHEAD OF THIS FEATURE. AT THE SURFACE, A 994MB LOW IS
CENTERED NEAR CINCINNATI OHIO. A WARM FRONT EXTENDS EAST OF THIS
FEATURE ACROSS CENTRAL WEST VIRGINIA. A STRONG COLD FRONT EXTENDS
SOUTHWEST OF THIS FEATURE INTO THE SOUTHERN PLAINS. SHOWERS HAVE MOSTLY
PUSHED EAST OF THE AREA WITH A PATCH OF MID-LEVEL DRYING MOVING
ACROSS THE AREA. SCATTERED CONVECTION ACROSS WEST VIRGINIA REMAINS
ON A TRAJECTORY FOR THE SOUTHEASTERN RIDGES.
TODAY...THE SURFACE LOW WILL PASS JUST WEST OF THE AREA THIS
MORNING AND BE CENTERED OVER LAKE ERIE BY 18Z. THIS WILL BRING A
BRIEF SURGE OF WARM AIR ADVECTION AHEAD OF THE COLD FRONT AS IT
APPROACHES FROM THE WEST. THE COLD FRONT WILL SWING UNDERNEATH THE
LOW AND BRING MUCH COLDER TEMPERATURES BY AFTERNOON. MORNING RAIN
SHOWERS WILL TRANSITION TO SNOW SHOWERS IN THE AFTERNOON AS
TEMPERATURES FALL THROUGH THE 30S. A TIGHT PRESSURE GRADIENT WITH
COLD ADVECTION AND A FAIRLY HIGH INVERSION WILL ALLOW FOR VERY
GUSTY WINDS ALONG AND BEHIND THE FRONT. A HIGH WIND WARNING FOR
THE RIDGES AND A WIND ADVISORY FOR THE LOWLANDS REMAIN IN EFFECT.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY/...
STRONG COLD ADVECTION IN WEST TO NORTHWEST FLOW TONIGHT INTO
SATURDAY WITH SNOW SHOWERS INTO SATURDAY EVENING. BEST
ACCUMULATION WILL BE IN THE SOUTHEAST RIDGES WITH TOTAL SNOWFALL
OF 3 TO 6 INCHES EXPECTED OVER A 24 TO 36 HOUR PERIOD WITH 2 TO 4
ACROSS THE I-80 CORRIDOR AND AN INCH OR LESS ELSEWHERE.
TEMPERATURES WELL BELOW NORMAL INTO SATURDAY NIGHT. WINDS WILL
DIMINISH BUT REMAIN QUITE GUSTY INTO SATURDAY. SURFACE RIDGE WILL
WORK EAST ACROSS REGION LATER SATURDAY NIGHT AND SUNDAY
DIMINISHING SNOW SHOWERS SATURDAY EVENING AND CLEARING SKIES
SUNDAY. TEMPERATURES SUNDAY WILL RECOVER TO NEAR NORMAL.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
HIGH PRESSURE WILL MAINTAIN DRY AND ABOVE SEASONABLE CONDITIONS FOR
THE FIRST HALF OF THE LONG TERM PERIOD AS AN UPPER LEVEL SHORTWAVE
CROSSES THE NORTHERN GREAT LAKES MONDAY. BOTH THE ECMWF AND GFS HAVE
THIS WAVE AND IT`S ATTENDANT SURFACE LOW PRESSURE SYSTEM STRETCH A
FRONT JUST ACROSS THE LOWER GREAT LAKES. THIS FRONT THEN BECOMES A
MECHANISM FOR WHICH ADDITIONAL WAVES WILL RIDE ALONG...SIMILAR TO
TODAY`S LOW PRESSURE SYSTEM.
WHILE TIMING AND STRENGTH ISSUES BEGIN TO DEVELOP BETWEEN THE
MODELS...BOTH THE GFS/ECMWF DEVELOP A LOW THAT IS PROGGED TO
APPROACH THE REGION TUESDAY NIGHT AND WEDNESDAY BRINGING RAIN
WEDNESDAY AND A CHANGE TO SNOW SHOWERS FOR THURSDAY.
WITH DECENT MODEL CONSENSUS THROUGH THE PERIOD...KEPT A BLEND OF THE
GFS/ECMWF WHICH IS CLOSE TO HPC GUIDANCE NUMBERS. THIS MAINTAINS
TEMPERATURES ABOUT 5-10 DEGREES ABOVE NORMAL MONDAY THROUGH
WEDNESDAY FOLLOWED BY A RETURN TO SEASONABLE LEVELS BY LATE
THURSDAY.
&&
.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
SHOWERS HAVE ENDED ACROSS ALL PORTS AS UPPER SHORT WAVE MOVES EAST
OF THE RIDGES. MOST LOCATIONS WILL MAINTAIN VFR FLIGHT CONDITIONS,
EXCEPT KFKL AND KDUJ WHICH CAN EXPECT PERIODS OF MVFR TO IFR CEILING
BEFORE DAYBREAK. CEILINGS IN THE NORTH WILL IMPROVE AFTER SUNRISE.
WINDS WILL BE THE MAIN AVIATION HAZARD FOR FRIDAY.
NAM MODEL PROFILES SHOW WINDS INCREASING IN SPEED TO 40 KTS AT ABOVE
2 KFT AGL LATE TONIGHT, WHILE WINDS IN THE STABLE SURFACE LAYER
REMAIN LESS THAN 10 KTS. HENCE EXPECT LOW LEVEL WIND SHEAR TO
DEVELOP WITH THE WARM FRONTAL PASSAGE 10Z-14Z.
DURING THE COLD FRONTAL PASSAGE, 13Z-18Z, VERTICAL MIXING WILL HELP
SOUTHWEST WINDS TO GUST OVER 30 KTS. POSTFRONTAL WINDS ALOFT WILL BE
FASTER, HENCE SURFACE WIND GUSTS MAY PEAK AT OVER 40 KTS, 18Z-03Z.
OUTLOOK...FRIDAY NIGHT THROUGH TUESDAY...
A PROLONGED PERIOD OF RESTRICTIONS LIKELY WITH POST-SYSTEM
LAKE-ENHANCED SNOW SHOWERS FRIDAY NIGHT AND SATURDAY, PARTICULARLY
NORTH AND NEAR THE MOUNTAINS. VFR SUNDAY INTO TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...HIGH WIND WARNING FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR MDZ001.
OH...WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM EST THIS EVENING
FOR OHZ039>041-048>050-057>059-068-069.
PA...WIND ADVISORY FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR PAZ007>009-013>016-020>023-029-031-073-075.
HIGH WIND WARNING FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR PAZ074-076.
WV...WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM EST THIS EVENING
FOR WVZ001>004-012.
WIND ADVISORY FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR WVZ021-022.
HIGH WIND WARNING FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1246 AM EST FRI FEB 24 2012
.UPDATE...
ISSUED AT 935 PM EST THU FEB 23 2012
BASICALLY MOVED THE TOTAL SNOWFALL NORTHWARD. A WINTER STORM
WARNING IS NOW IN EFFECT FOR ALL COUNTIES BUT THE NRN ROW...WHERE
A WINTER WEATHER ADVISORY IS IN EFFECT.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 945 PM EST THU FEB 23 2012
THE GFS AND NAM CONTINUE TO SHOW THE TROWAL ORIENTED ENE FROM THE
MKG/GRAND HAVEN AREA TO SAGINAW BAY. THE HRRR PCPN FIELDS ALSO
POINT TO THIS. LOOKING AT THE LATEST IR IMAGERY...THE SRN EDGE OF
THE COLDER CLOUD TOPS LINE UP WITH WHERE THE MODELS INDICATE THE
TROWAL WILL SET UP. ALL OF THIS SUGGESTS TO ME THAT THE MAX
SNOWFALL WILL BE A BIT FARTHER NORTH THAN WHERE WE EARLIER
THOUGHT. AS SUCH...WE ADDED SOME WARNING HEADLINES TO COVER THE
CWA EXCEPT FOR THE FAR NRN ROW...WHERE WE ADDED AN ADVISORY.
MAX FGEN WILL SET UP OVER THE CENTRAL CWA AND A GENERAL 5-9 INCH
SNOW CAN BE EXPECTED. HEAVIEST SNOWFALL WILL LIKELY BEGIN AFTER
MIDNIGHT AND CONTINUE INTO FRIDAY MORNING. THIS SNOW WILL BE A
WET/HEAVY SNOW AND WILL HAVE AN IMPACT ON THE MORNING COMMUTE. THE
PCPN WILL END FROM WEST TO EAST FRIDAY LATE MORNING/AFTERNOON.
AFTER THE UPPER UPPER LOW MOVES EAST OF THE AREA FRIDAY
AFTERNOON... THAT ALLOWS THE BETTER COLD ADVECTION TO BEGIN. WITH
CYCLONIC FLOW... 850 MB TMPS BELOW -10C MOVING IN WITH DEEP
MOISTURE ON NORTHWEST WINDS... LAKE EFFECT SNOW DEVELOPS AND
CONTINUES THROUGH THE NIGHT. THE BEST SNOWFALL FOR THIS WILL BE
DURING THE OVERNIGHT HOURS. ANOTHER 2 TO 4 INCHES ARE EXPECTED
WITH THAT IN THE TYPICAL NW FLOW AREAS. THIS TIME THROUGH THE AIR
TEMP WILL BE BELOW FREEZING SO THIS SNOW WILL BE MORE OF A FLUFFY
SNOW. ONCE AGAIN THERE IS GOOD LIFT IN THE DGZ BUT THE BEST LIFT
IS ACTUALLY BELOW THE DGZ SO THIS WILL NOT BE AS FLUFFY AS SOME
LAKE EFFECT EVENTS HAVE BEEN.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 415 PM EST THU FEB 23 2012
LINGERING LAKE EFFECT SNOW SHOWERS SATURDAY MORNING WILL END IN THE
AFTERNOON AS UPPER LEVEL FLOW BECOMES ANTICYCLONIC. DRY WEATHER IS
FORECAST SATURDAY NIGHT AND SUNDAY WITH UPPER RIDGING IN PLACE.
AT THIS TIME WE WILL MAINTAIN VERY LOW POPS FOR SUNDAY NIGHT INTO
MONDAY AS WEAK LOW PRESSURE MOVES ACROSS THE LAKE SUPERIOR REGION.
HOWEVER IT IS NOTED THAT OVERALL MEDIUM RANGE GUIDANCE TRENDS KEEP
LIGHT QPF TIED TO THIS SYSTEM NORTH OF OUR FCST AREA... SO FUTURE
SHIFTS MAY BE ABLE TO GO WITH A DRY FCST SUNDAY NIGHT/MONDAY.
A BETTER CHC FOR PCPN SHOULD COME FOR THE MIDDLE PORTION OF NEXT
WEEK AS A SOUTHERN PLAINS LOW TRACKS ENE INTO THE LOWER GREAT LAKES
REGION BY TUESDAY NIGHT/WEDNESDAY. LIGHT PCPN MAY ARRIVE AS EARLY AS
TUESDAY PRECEDING THAT SYSTEM... BUT THE BETTER CHC FOR PCPN SHOULD
HOLD OFF UNTIL TUESDAY NIGHT AND WEDNESDAY AS SUGGESTED BY 12Z ECMWF
GUIDANCE.
TRENDED THE MAX TEMP FCST A BIT MILDER FOR WEDNESDAY WITH POTENTIAL
FOR A RAIN/SNOW MIX. TEMPS SHOULD AVG NEAR TO SLIGHTLY ABOVE NORMAL
THROUGH THE LONG RANGE FCST PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY EVENING)
ISSUED AT 1246 AM EST FRI FEB 24 2012
A LONG DURATION SNOW EVENT IS UNDERWAY THAT WILL RESULT IN VARYING
CIGS/VSBYS. EXPECT IFR/LIFR FOR MUCH OF THE PERIOD WITH VSYBS MOSTLY
AROUND A MILE...BUT AT TIMES DOWN TO A HALF MILE AND UP TO 3 MILES.
CONDITIONS WILL IMPROVE FRIDAY AFTERNOON.
&&
.MARINE...
ISSUED AT 415 PM EST THU FEB 23 2012
I HAVE ISSUED A SMALL CRAFT ADVISORY DUE TO THE INCREASING NORTH
WINDS TONIGHT THROUGH SATURDAY AFTERNOON. WINDS SHOULD INCREASE TO
15 TO 25 KNOTS OVERNIGHT AND CONTINUE INTO SATURDAY BEFORE
DIMINISHING DURING THE LATE AFTERNOON.
&&
.HYDROLOGY...
ISSUED AT 415 PM EST THU FEB 23 2012
THERE ARE NO WARNINGS OR ADVIOSRIES IN EFFECT FOR AREA RIVERS OR
STREAMS. TEMPERATURES ARE NOT EXPECTED TO GET COLD ENOUGH FOR ICE
JAMS TO BE AN ISSUE. METLING OF THE SNOW THAT FALLS SHOULD BE SLOW
ENOUGH TO NOT BE MUCH OF AN ISSUE EITHER.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING UNTIL NOON EST FRIDAY FOR MIZ043>046-
050>052-056>059-064>067-071>074.
WINTER WEATHER ADVISORY UNTIL NOON EST FRIDAY FOR MIZ037>040.
LM...SMALL CRAFT ADVISORY UNTIL 7 PM EST SATURDAY FOR LMZ844>849.
&&
$$
UPDATE...93
SHORT TERM...WDM 93
LONG TERM....LAURENS
AVIATION...93
MARINE...WDM
HYDROLOGY...WDM
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1221 AM EST FRI FEB 24 2012
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 423 PM EST THU FEB 23 2012
WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH
FROM MANITOBA AND NRN ONTARIO INTO THE SRN PLAINS. A VIGOROUS
SHORTWAVE TROUGH MOVING THROUGH SRN NEBRASKA SUPPORTED A BAND OF
MODERATE TO HEAVY SNOW OVER SE SD INTO NRN IA AND RAIN TO THE EAST.
AN UPSTREAM SHRTWV NEAR LAKE WINNIPEG WAS BRINGING MAINLY JUST LIGHT
SNOW OR FLURRIES IN SRN MANITOBA AND NW ONTARIO. AT THE SFC...A 990
MB LOW WAS LOCATED OVER SE MO WHILE A WEAKER 1002 MB LOW MOVING
THROUGH SE MANITOBA. A WEAK TROUGH EXTENDED FROM WEST TO EAST ACROSS
UPPER MI LEAVING VERY LIGHT WINDS OVER THE AREA. WITH PLENTY OF LOW
LEVEL MOISTURE IN PLACE THE WEAK NNE FLOW COMBINED WITH 850 MB TEMPS
AROUND -9C WAS ENOUGH TO SUPPORT SOME LIGHT SNOW SHOWERS INTO N
CNTRL UPPER MI.
EXPECT AREAS OF LIGHT SNOW SHOWERS OR FLURRIES TO PERSIST INTO THIS
EVENING CNTRL AND WEST WITH THE TROUGH OVER THE AREA AND WEAK FLOW
OFF OF LAKE SUPERIOR. ANY ACCUMULATIONS SHOULD ONLY AMOUNT TO A
TRACE OR A FEW TENTHS. AS THE MANITOBA SHRTWV MOVES TOWARD THE AREA
LATE TONIGHT INTO FRIDAY...MID LEVEL QVECTOR CONV ASSOCIATED WITH
THIS FEATURES WILL SUPPORT AN EXPANDING AREA OF LIGHT SNOW FROM NE
MN INTO WRN LAKE SUPERIOR AND WEST UPPER MI. SINCE THE NNW WINDS LOW
LEVEL WINDS FCST REMAIN RELATIVELY LIGHT THERE IS STILL SIGNIFICANT
UNCERTAINTY REGARDING THE LAKE ENHANCED SNOW POTENTIAL INTO WEST
UPPER MI AS THE HIGH RES MODELS SHOW DIFFERING SCENARIOS. THE BEST
CHANCE FOR SNOW OVER THE WEST IS EXPECTED DURING THE AFTERNOON AS
THE SHORTWAVE APPROACHES AND COLDER AIR MOVES IN WITH 850 MB TEMPS
DROP TO NEAR -12C. IF STRONGER LOW LEVEL CONV OR ONSHORE WINDS
DEVELOP SNOW AMOUNTS OF A COUPLE INCHES WILL BE POSSIBLE BY EVENING.
SCT -SHSN SHOULD ALSO DEVELOP OVER THE REST OF NRN UPPER MI AS NRLY
WINDS INCREASE. HOWEVER...SINCE THE DEEPER MOISTURE REMAINS TO THE
WEST...ONLY CHANCE POPS WERE INCLUDED.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 423 PM EST THU FEB 23 2012
FRI NGT...A CYC NLY FLOW WL DOMINATE THE UPR GRT LKS AS A SHRTWV
DIGGING SEWD THRU MN MAINTAINS LOWER HGTS/HIER MID LVL RH OVER THE
UPR LKS. ALTHOUGH THE FCST H85 TEMPS IN THE -12C TO -14C ARE NOT
PARTICULARLY COLD...OPTED TO MAINTAIN LIKELY POPS IN AREAS FAVORED
BY THE NNW LLVL FLOW GIVEN THE DEEP MSTR PROFILE. WENT WITH THE
HIER POPS OVER THE W CLOSER TO THE TRACK OF THE MN DISTURBANCE.
SAT...EXPECT LINGERING LES IN THE MRNG TO DIMINISH WITH THE APRCH OF
SHRTWV RDG IN PROGRESSIVE FLOW ALF AND ARRIVAL OF RISING H5 UP TO
100M BTWN 12Z-24Z/SFC HI PRES IN THE WAKE OF DEPARTING SHRTWV.
ALTHOUGH FCST LLVL NW FLOW IS FAVORABLE FOR LES IN AREAS E OF MQT...
MODELS CONSISTENTLY SHOW DRY AIR IN ONTARIO PASSING OVER ERN LK SUP
AND LIMITING SN CHCS OVER THE ERN CWA. SO CUT POPS/SN AMOUNTS SHOWN
IN PREVIOUS FCSDT.
SAT NGT...ALTHOUGH A FEW -SHSN MAY LINGER NEAR LK SUP IN THE EVNG...
BACKING FLOW TO THE SSW OVERNGT WITH PASSAGE OF RDG AXIS TO THE E
AND APRCH OF STRONG SHRTWV/SFC LO THRU THE NRN PLAINS WL PUSH ANY
REMAINING -SHSN OUT INTO THE OPEN LAKE. WITH SOME CLRG/LGT WINDS
UNDER THE RDG AXIS/PWAT ARND 0.15 INCH...TEMPS OVER THE INTERIOR MAY
FALL SHARPLY IN THE EVNG BEFORE THICKENING HI/MID CLDS RETURN LATE
WITH DVLPG ISENTROPIC ASCENT AHEAD OF THE INCOMING SHRTWV/SFC LO AND
CAUSE READINGS TO RISE LATER. TENDED TOWARD THE LO END OF GUIDANCE
FOR MIN TEMPS IN THIS AREA WITH A NON DIURNAL TEMP TREND.
SUN/SUN NGT...MODELS HAVE TRENDED A BIT FASTER WITH THE INCOMING
FCST LO PRES AS SUPPORTING SHRTWV IS FCST TO SHEAR OUT AS IT MOVES
INTO CONFLUENCE ZN BTWN MEAN RDG OVER THE SE CONUS AND PERSISTENT
WNW FLOW ALF OVER NE CAN ON SW FLANK OF CLOSED LO NEAR THE DAVIS
STRAIT. ALTHOUGH THE 12Z GFS SHOWS A MORE SHEARED OUT/WEAKER
DISTURBANCE WHILE THE CNDN MODEL DEPICTS A DEEPER SYS...VARIOUS
GUIDANCE IS IN GOOD AGREEMENT SHOWING THE LO PRES TRACK ACRS THE NRN
TIER OF THE CWA/SRN LK SUP. THIS TRACK SHOULD MINIMIZE THE THREAT OF
SGNFT SN ACCUM OVER THE FA WITH MORE PERSISTENT DEEPER FGEN UNDER
DEFORMATION ZN PASSING TO THE W AND N AND POTENTIAL DRY SLOTTING
ESPECIALL OVER THE SRN TIER CLOSER TO SUPPORTING JET CORE AXIS.
HOWEVER...COMBINATION OF FAIRLY SHARP UPR DVGC IN LEFT EXIT OF
SUPPORTING H3 JET MAX/FAIRLY VIGOROUS ISENTROPIC ASCENT SHOWN ON THE
285K SFC /ABOUT H75/ IN THE WAD PATTERN N OF ATTENDANT WARM FNT/DEEP
LYR QVECTOR CNVGC WARRANT FCST HI LIKELY POPS SPREADING IN BY AFTN.
GIVEN FCST H7 SPECIFIC HUMIDITY OF 2 G/KG...SUSPECT UP TO 2 TO 4
INCHES OF SN MAY FALL OVER THE NW CWA ON SUN...ESPECIALLY SINCE GFS
FCST SDNGS SHOW SHARP OMEGA WITHIN THE DGZ IN THAT AREA. EXPECT THE
SYNOPTIC SCALE PCPN TO DIMINISH TO LES W-E BY EARLY MON MORNING
WITH LARGE SCALE QVECTOR DVGC/DRYING FOLLOWING THE SHRTWV/SFC LO.
SINCE THERE IS A POTENTIAL FOR ADVY SN WITH THIS DISTURBANCE...OPTED
TO RETAIN MENTION IN HWO.
IN THE EXTENDED RANGE...SOME LES IS LIKELY ON MON UNDER THE MOIST
NNW FLOW LEFT IN THE WAKE OF THE DEPARTING LO THRU SE CAN AND WITH
H85 TEMPS PROGGED TO DIP AS LO AS -15C. THE ARRIVAL OF A HI PRES RDG
WL BRING QUIET WX ON TUE. ANOTHER DISTURBANCE/SFC LO MOVING IS FCST
TO MOVE THRU THE OH VALLEY ON WED. THERE HAS BEEN CONSIDERABLE MODEL
DISAGREEMENT ON THE TRACK OF THIS SHRTWV...SO RELIED ON THE
CONSENSUS OF THE MODELS FOR THE FORECAST IN THAT PERIOD. BEST SHOT
FOR ANY ACCOMPANYING SN WL BE OVER THE S. WITH HI PRES FOLLOWING
THIS SYSTEM NEXT THU...EXPECT A DRYING TREND THEN. SINCE THE
PREVAILING ZONAL FLOW ALF THRU THE EXTENDED PERIOD WL LIMIT ARCTIC
AIR INTRUSION INTO THE CONUS...EXPECT ABV NORMAL TEMPS TO PERSIST.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1220 AM EST FRI FEB 24 2012
LIGHT NORTHERLY CONVERGENT WINDS MAY RESULT IN OCCASIONAL IFR
CONDITIONS IN LIGHT LAKE EFFECT SNOW AT KSAW THROUGH 10Z...ALTHOUGH
SNOW SHOULD DIMINISH TO FLURRIES THEREAFTER. A LIGHT NRLY FLOW AND
MARGINAL OVER-WATER INSTABILITY SHOULD CONTINUE MVFR CONDITIONS AT
KSAW AND KCMX THROUGH MUCH OF TONIGHT INTO FRIDAY EVENING. AT
KIWD...MVFR CONDITIONS ARE EXPECTED TO GIVE WAY TO IFR CONDITIONS BY
LATE FRIDAY AFTERNOON AS LOW-LVL CONVERGENCE INCREASES AND
ENHANCEMENT OF LAKE EFFECT SNOW IS POSSIBLE FROM UPPER DISTURBANCE
MOVING ACROSS THE AREA.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 423 PM EST THU FEB 23 2012
NRLY WINDS INCREASING INTO THE 15 TO 25 KT RANGE ARE EXPECTED LATE
FRIDAY INTO FRIDAY NIGHT AS THE GRADIENT INCREASES IN THE WAKE OF
LOW PRESSURE MOVING TOWARD THE SRN GREAT LAKES. A LOW PRESSURE
SYSTEM MOVING THROUGH THE UPPER GREAT LAKES SUNDAY INTO MONDAY WILL
ALSO BRING A PERIOD OF STRONGER WINDS. SE WINDS TO 30 KT ARE
EXPECTED IN ADVANCE OF THE LOW ON SUN. AS THE LOW MOVES TO THE EAST
OF THE AREA MONDAY NORTH TO NORTHWEST WINDS OF 20 TO 30 KT ARE ALSO
EXPECTED.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
NONE.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...KC
AVIATION...VOSS
MARINE...JLB
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1117 PM CST Thu Feb 23 2012
...UPDATED AVIATION DISCUSSION...
.DISCUSSION...
As expected, temperatures soared well into the 60s within the warm
sector early this afternoon, even more so than anticipated with the
earlier update. 20Z surface analysis continued to show a complex
frontal structure with two surface lows extending from near Omaha to
near Moberly, with most of the CWA now located in the post-frontal
airmass. Gusty northwest winds will continue to surge east across
the remainder of the CWA through 00Z, accompanied by extensive
cloud cover and steadily falling temperatures.
Two primary concerns as we head into this evening.
1.) Wind. The RUC13 has done an outstanding job with the
placement/intensity of strong winds across Nebraska/Kansas today,
which justifies my earlier concern with respect to the ongoing wind
advisory. Increasing friction (terrain, trees, etc...) over the
eastern Plains coupled with the loss of daytime heating will both
act against a simple advection of upstream conditions into the
western CWA this evening. Already pushed back the start time of the
wind advisory until 6PM, which looks reasonable given the
juxtaposition of the strongest winds immediately south/southeast of
the digging mid-level trough axis. However, considering both minimal
impacts (after the evening commute) and the aforementioned
meteorology, am concerned that the advisory may no longer be
warranted. Still, we may see both sustained speeds and gusts locally
meet criteria (30/45), and will leave the headline active through
this evening. Still will be a windy/blustery evening regardless,
with 60s giving way to 30s by midnight.
2.) Precipitation. Satellite presentation with the mid level trough
over eastern Nebraska continues to improve this afternoon, and
additional deepening is expected as the wave digs southeast along
the Nebraska/Missouri border overnight. A compact area of vigorous
ascent and diabatic cooling immediately behind the trough, acting as
a small scale deformation band, may affect the far northern tier
counties between 9-10PM and shifting east through the overnight
hours. Given favorable dendritic snow growth profiles, it is
possible that a period of moderate to heavy snow could brush the
Iowa border counties, resulting in minor accumulations. Do expect
Iowa/Illinois to receive the brunt of this evening and for now have
painted an inch across the northern counties, but would not be
surprised if a short-fused advisory became necessary overnight.
Evening hazardous weather outlook will be amended as necessary to
reflect this impact. If concerns #1 and
#2 overlap at some point tonight, we could have an additional issue
with blowing snow/visibilities impacting travel north of highway 36.
Otherwise, gusty winds and strong cold advection will continue into
tomorrow. Previous forecast already reflected undercutting guidance
on temperatures and made no change there. Cyclonic flow will
maintain cloud cover, especially over the northeast half of the CWA
and would not be surprised to see a few sprinkles/flurries from time
to time either.
Return flow comes back in a hurry Saturday afternoon, with winds
increasing over the western CWA. Should see another 10-15 degree
gradient from northeast Missouri to eastern Kansas.
Bookbinder
Medium Range (Sunday through Thursday)...
The focus for the weather over the latter half of the forecast is on
two features; the first a shortwave due to zip east through the
Northern Plains into the Great Lakes Saturday into Sunday; the
second shortwave of note will then follow on quickly through the
Central Plains Monday night through Wednesday.
Leading shortwave, due to pass through the Plains Saturday/Sunday,
will be starved for moisture. A surface high slowly shifting east
along the Gulf Coast will effectively shut off any return moisture
from the Gulf over the weekend. Couple that observation with the
notable speed with which this shortwave jets east through the
Northern Plains, and precipitation of any form for the weekend looks
like a non-issue. Have kept the forecast dry, and boosted afternoon
highs on the expectation of breezy southwest winds. This should put
temperatures for the last day of the weekend into the 50s to low
60s.
After the passage of the weekend leading shortwave, a second wave is
due to pass through the Central Plains during the beginning of the
work week. Sunday`s shortwave, while dry, will have the ultimate
effect of shoving the baroclinic zone a little father south as weak
high pressure oozes into the Northern Plains, pushing afternoon
highs back down towards normal. This results in the second wave
kicking out across the plains form the Four Corners region, zipping
through the Lower Missouri River Valley. At this point the surface
high along the Gulf Coast will have advected east under the
influence of the progressive flow across the nation, leaving the
Gulf open to allow moisture return which the second shortwave will
be able to tap.
This second system has the potential to be significant weather
maker. While models are in decent enough broad agreement on the
general trend of the shortwave to warrant including likely POPs for
part of Tuesday and Tuesday night, preference on the specifics of
shortwave timing are hedged towards the faster ECMWF and GEM
solutions. GFS is the slowest in ejecting the wave, which seems a
bit off given the progressive flow. Anyhow, have limited snow POPs
to the Iowa border region where the coolest air will be, but
otherwise have a mix of rain and rain/snow across the various
forecast periods from Monday night through Wednesday. Did add in
isolated thunder for areas along and south of I-70 owing to some
limited instability present during the afternoon Tuesday.
Cutter
&&
.AVIATION...
For the 06Z TAFS, MVFR ceilings are expected over the next 5 to 6
hours as a storm system moves across southern IA and northern MO.
Cigs should generally be around 2k to 2.5k ft but may temporarily
fall into the 1.5k range as lower ceilings wrap around the back edge
of the system. Skies should scatter out around sunrise but strong
cold advection aloft should result in cigs becoming broken again but
remaining VFR through the afternoon. As the cold air aloft get
shifted east skies should start to scatter or clear out around sunset.
Strong northwesterly winds will continue but will decrease through
the overnight as the pressure gradient weakens. Winds through the
night should still gust in the 20 to 30 kt range, decreasing through
the morning hours. Winds should then become gusty again late in the
morning and into the afternoon hours before diminishing around sunset.
CDB
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
352 AM CST FRI FEB 24 2012
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT
FAIRLY ACTIVE PATTERN THROUGH THE NEXT WEEK WITH THE SHORT TERM
FOCUS ON FRIDAY WITH A WEAK SHORTWAVE TROUGH MOVING ACROSS THE
AREA WITH CHANCES FOR SNOW SHOWERS AND WINDY CONDITIONS AGAIN. A
BRIEF WARM UP IS EXPECTED FOR SATURDAY...ALONG WITH WINDY
SOUTHERLY WINDS...THEN FOCUS TURNS TO PRECIPITATION CHANCES AND
WINDS AGAIN ON SUNDAY AND SUNDAY NIGHT AS THE NEXT SYSTEM MOVES
ACROSS THE AREA.
AT 08Z WATER VAPOR SHOWED THE TROUGH THAT BROUGHT THE STRONG WINDS
TO THE AREA YESTERDAY HAD PUSHED INTO MISSOURI AND ILLINOIS WITH
RIDGING CONTINUING OVER THE WESTERN CONUS...KEEPING THE LOCAL AREA
UNDER NORTHWEST FLOW. LOOKING UPSTREAM...IS SOME DARKENING IN THE
WATER VAPOR OVER ALBERTA WHICH IS CONFIRMED BY LOWERED PRESSURE ON
THE 1.5PV SURFACE BY THE RUC ANALYSIS. FURTHER UPSTREAM...A ROBUST
SHORTWAVE TROUGH WAS MAKING ITS WAY ACROSS THE NORTHERN PACIFIC.
AT THE SURFACE...THE SURFACE LOW HAD MOVED EAST AND WAS OVER
ILLINOIS...WITH HIGH PRESSURE OVER COLORADO. WINDS HAD SUBSIDED
OVERNIGHT AS THE PRESSURE GRADIENT RELAXED. LAPS RATES REMAINED
QUITE STEEP AS INDICATED BY LAPS SOUNDINGS ACROSS THE FORECAST
AREA WHICH HAS HELPED TO CONTINUE SOME SCATTERED SHOWERS MOVING
SOUTHEAST ACROSS THE CENTRAL PART OF THE FORECAST AREA.
OBSERVATIONS ARE INDICATING CEILINGS MAINLY AT 5K FEET AND RADAR
ECHOES ARE QUITE LIGHT AND NOT STABLE SO DON/T THINK THERE IS
MUCH/IF ANYTHING REACHING THE SURFACE.
FOR TODAY...ALTHOUGH THERE WILL BE WARM AIR ADVECTION ALOFT /ABOVE
600MB AS RIDGING SLOWLY BUILDS IN...LAPS RATES BELOW 600MB WILL
REMAIN STEEP /7-8 DEGREES PER KM/ AND AS THE SHORTWAVE OVER
ALBERTA MOVES SOUTHEAST BRINGING SOME EXTRA LIFT ACROSS THE AREA
LATER THIS MORNING AND THIS AFTERNOON...EXPECTING ISOLATED TO
SCATTERED SNOW SHOWERS MAINLY EAST OF A PINE RIDGE TO NORTH PLATTE
LINE. THERE ISN/T MUCH MOISTURE TO WORK WITH SO DON/T EXPECT
MUCH/IF ANY FOR ACCUMULATIONS. OTHER CONCERN FOR TODAY IS WINDS.
ALTHOUGH THE PRESSURE GRADIENT WON/T YIELD STRONG WINDS...THE
STEEP LAPSE RATES /GOOD MIXING/ WILL LIKELY BRING ABOUT SOME WINDY
CONDITIONS. BUFKIT FORECAST SOUNDINGS FROM THE NAM INDICATE WINDS
AT THE TOP OF THE MIXED LAYER THIS AFTERNOON OF 35 TO 45KTS. WHILE
THE GFS IS A BIT HIGHER...UP TO 50KTS AT 700MB. AS THIS ISN/T A
STRONG COLD AIR ADVECTION/SUBSIDENT REGIME...EVEN THOUGH HAVE THE
STRONG LAPSE RATES...DON/T KNOW IF THOSE WINDS WILL BE ABLE TO BE
MIXED TO THE SURFACE. DID INCREASE WINDS IN THE FORECAST...AND MAY
HAVE A FEW POINTS THAT REACH ADVISORY CRITERIA...BUT WITH
CONFIDENCE LESS THAN 50 PERCENT AND IT BEING LOW END AND NOT
WIDESPREAD OPTED TO NOT ISSUE ANY HEADLINES FOR TODAY. DAYSHIFT
CAN MONITOR IF THE WINDS INCREASE TOO MUCH AND IF AN ADVISORY WOULD
BE NEEDED.
THE TROUGH OVER THE NORTHERN PACIFIC WILL PUSH OVER THE RIDGE
TONIGHT AND SATURDAY...WITH LOW PRESSURE DEVELOPING AT THE SURFACE
ON THE LEE SIDE OF THE ROCKIES OVER MONTANA/WYOMING AND COLORADO.
THIS WILL BRING A BRIEF WINDOW OF RIDGING ACROSS THE PLAINS...WITH
WARMER TEMPERATURES EXPECTED FOR SATURDAY. THERE LOOKS TO BE
PLENTY OF SUNSHINE...BUT WITH JUST A QUICK WINDOW FOR WARMING ONLY
HAVE FORECAST HIGHS IN THE 40S TO MID 50S IN THE SOUTH. SOUTHERLY
WINDS WILL ALSO BE PRETTY BREEZY ON SATURDAY AS THE LOW PRESSURE
TO THE WEST STRENGTHENS. CURRENTLY LOOKS LIKE WINDS WILL STAY
BELOW ADVISORY CRITERIA.
THE UPPER LEVEL LOW WILL TRACK NORTH OF THE AREA /OVER THE
DAKOTAS/ AS WILL THE SURFACE LOW. THE COLD FRONT WILL PASS THE
FORECAST AREA SATURDAY NIGHT...BRINGING A WIND SHIFT...BUT LITTLE
IF ANY PRECIPITATION TO ALL BUT THE NORTHERN TIER OF COUNTIES.
DEEP MOISTURE WILL FOR THE MOST PART STAY NORTH OF THE AREA SO
WILL JUST CONTINUE THE SLIGHT CHANCES FOR SNOW OVER THE NORTHERN
COUNTIES. AGAIN...WINDY CONDITIONS ARE EXPECTED BEHIND THE COLD
FRONT WITH A FAIRLY TIGHT PRESSURE GRADIENT ACROSS SOUTH DAKOTA
AND INTO NEBRASKA THROUGH SUNDAY. STRONGEST WINDS LOOK TO BE NORTH
OF THE HIGHWAYS 2 AND 91 CORRIDOR.
.LONG TERM...MONDAY THROUGH THURSDAY
THIS PERIOD ALSO LOOKS FAIRLY ACTIVE WITH A STRONG SYSTEM
PROJECTED TO MOVE ACROSS THE CENTRAL PLAINS MONDAY NIGHT THROUGH
WEDNESDAY. THE UPPER LEVEL SYSTEM WILL MOVE ONSHORE ON
MONDAY...THEN TRACK TOWARDS THE CENTRAL PLAINS MONDAY NIGHT. THE TRACK
OF THIS SYSTEM HAS TRENDED NORTH...WHICH BRINGS WARMER AIR INTO
PLAY WHICH COULD CAUSE ISSUES WITH PRECIPITATION TYPE. THE LOW
LEVEL FLOW WOULD SUGGEST A WIDE OPEN GULF WITH STRONG MOISTURE
TRANSPORT NORTHWARD. ALSO...LOOKING AT THE ISENTROPIC
SURFACES...STRONG LIFT ALONG WITH SPECIFIC HUMIDITIES OF 5 TO 6
G/KG INTO SOUTHWEST NEBRASKA INDICATE PLENTY OF JUICE FOR
PRECIPITATION. THE SURFACE LOW DEEPENS OVER EASTERN COLORADO AND
A WARM FRONT PUSHES NORTH INTO NEBRASKA MONDAY NIGHT. THE MODEL
SOLUTIONS HAVE COME INTO DECENT AGREEMENT WITH BRINGING THE WARM
AIR INTO MUCH OF THE FORECAST AREA...WHICH COULD BE WARM ENOUGH
FOR A RAIN/SNOW MIX OR JUST RAIN ACROSS SOUTHERN INTO NORTHEAST
NEBRASKA MONDAY NIGHT INTO TUESDAY. DID RAISE LOW TEMPERATURES A
BIT BUT DUE TO THE LIKELIHOOD THAT THERE WILL BE CHANGES YET AS
THE SYSTEM GETS CLOSER...DIDN/T GO TOO WARM. THE GFS IS THE
WARMEST SOLUTION WHICH WOULD SUGGEST RAIN OVER THE ENTIRE FORECAST
AREA MONDAY NIGHT INTO TUESDAY. AT THIS POINT WANT TO EXERCISE
SOME CAUTION SO JUST WENT WITH A RAIN/SNOW MIX OVER THE
SOUTHEASTERN HALF WITH SNOW OVER THE PANHANDLE AND NORTHWEST
NEBRASKA. AS THE LOW MOVES EAST...ARCTIC AIR WILL COME SOUTH ON
THE BACK SIDE OF THE SYSTEM WHICH WILL SWITCH PRECIPITATION OVER
TO ALL SNOW BY THE END OF THE DAY TUESDAY. SOMETHING ELSE TO
CONSIDER AS THERE IS COLDER AIR TO DEAL WITH...ALONG WITH A GOOD
TONGUE OF WARM AIR ABOVE THE SURFACE IS IF THERE WILL BE AN AREA
OF FREEZING RAIN OR SLEET. AS WAS STATED EARLIER...STILL NOT A
GREAT DEAL OF CONFIDENCE IN HOW THIS WILL ALL PLAY OUT SO DIDN/T
WANT TO ADD THE FREEZING PRECIPITATION TYPES INTO THE FORECAST
QUITE YET. SOMETHING TO KEEP IN MIND THOUGH.
SHOULD GET A SMALL BREAK WEDNESDAY AND WEDNESDAY NIGHT BEFORE THE
NEXT SYSTEM CROSSES THE ROCKIES ON THURSDAY...SO HAVE CHANCES FOR
PRECIPITATION AGAIN FOR THURSDAY NIGHT.
&&
.AVIATION...
MAINLY VFR CONDITIONS THIS MORNING ACROSS THE AREA. A DISTURBANCE
WILL BRING A SLIGHT CHANCE FOR LIGHT SNOW SHOWERS ACROSS NORTHERN
INTO CENTRAL NEBRASKA TODAY. THE ISOLATED SNOW SHOWERS WILL BRING
POCKETS OF MVFR CIGS...AT OR ABOVE BKN020...THROUGH LATE AFTERNOON.
IMPACT OF MVFR IS EXPECTED TO REMAIN ALONG AND EAST OF A KIEN TO
KBBW LINE. WIDESPREAD VFR EXPECTED AFTER 00Z AS SYSTEM PUSHES
SOUTHEAST OF THE AREA.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT/LONG TERM...BROOKS
AVIATION...MASEK
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1122 PM EST THU FEB 23 2012
.SYNOPSIS...
LOW PRESSURE WILL LIFT ACROSS THE OHIO VALLEY AND EASTERN GREAT
LAKES TONIGHT...INTENSIFYING AS IT TRACKS ACROSS NORTHERN NEW
ENGLAND FRIDAY NIGHT. THIS WILL BRING SNOW TO THE REGION TONIGHT
THEN A CHANGE OF SNOW TO RAIN DURING FRIDAY MORNING. AS THE LOW
EXITS INTO THE CANADIAN MARITIMES...IT WILL BRING COLDER AIR
DEVELOPING LAKE EFFECT SNOW SHOWERS FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH FRIDAY/...
AS OF 1100PM...REGIONAL RADAR SHOWING A BAND OF WARM ADVECTION RAIN
AND SNOW SPREAD FROM SOUTHERN MICHIGAN EASTWARD ACROSS NORTHERN OHIO
TO WESTERN PA. MID AND HIGH LEVEL CLOUDS HAVE SPREAD NORTH INTO THE
BUF FORECAST AREA AHEAD OF THE STORM SYSTEM CENTERED OVER THE LOWER
OHIO VALLEY. TEMPS ACROSS THE FORECAST AREA ARE IN THE LOWER 30S
WHILE UPPER 30S ARE SEEN SOUTH INTO PA. AS THIS BAND OF RAIN LIFTS
NORTH OVER THE COOLER TEMPS ACROSS THE SOUTHERN TIER SNOW WILL BEGIN
TO FALL AND SHOULD COME IN PRETTY INTENSE ESPECIALLY WITH 40 TO 50
DBZ BEING OBSERVED ON RADAR MOSAIC NEAR THE NY/PA BORDER. LATEST
HRRR AND RUC MODELS CONTINUE TO SHOW SNOW MOVING INTO THE SOUTHERN
TIER NEAR MIDNIGHT AND INTO THE REST OF WESTERN NY BY 08Z-09Z. NO
IMPACTS TO THE NORTH COUNTRY UNTIL LIKELY NEAR/AFTER SUNRISE. POP/WX
GRIDS WHERE TWEAKED A BIT AND ARE INLINE WITH SHORT TERM MODELS.
PREVIOUS DISCUSSION...
LOW PRESSURE CENTERED NEAR SOUTHERN ILLINOIS THIS EVENING WILL SHIFT
NORTHEAST ACROSS THE OHIO VALLEY BY MORNING. 12Z NAM12 AND REGIONAL
GEM HAVE COME TO A CLOSER CONSENSUS AS TO THE
PLACEMENT/TIMING/INTENSITY TO A PRECIP BAND PRECEDING THE SURFACE
LOW. THESE MODELS SHOW STRONG 925-850MB FRONTOGENETIC FORCING OVER
SOUTHWESTERN AND WESTERN NY OVERNIGHT...WITHIN A LIKEWISE STRONG
WARM ADVECTION IN THESE SAME LAYERS. DEEP MOISTURE AND A DEEP OMEGA
PLUME TO ABOVE 25000FT AND A CO-LOCATED OMEGA MAXIMUM WITHIN THE
DENDRITIC GROWTH ZONE WILL MAXIMIZE THE SNOW POTENTIAL. EXPECT THIS
TO BE IN THE FAIRLY NARROW BUT INTENSE BAND LIFTING NORTHWARD ACROSS
WESTERN NY. WILL HAVE A WINTER WEATHER ADVISORY IN EFFECT FOR SNOW
TOTALS OF 4 TO 8 INCHES...SOME HEAVIER SNOW WITH RATES MORE THAN AN
INCH AN HOUR...AND THUNDER IS NOT OUT OF THE QUESTION.
THE HEAVIER SNOW BAND LIFTING NORTHWARD WILL ALSO AFFECT THE EASTERN
LAKE ONTARIO COUNTIES...LESSER IMPACT ALONG THE SOUTH SHORE OF LAKE
ONTARIO AS THE FRONTOGENETIC FORCING SLIDES AS LITTLE MORE TO THE
EAST AHEAD OF THE ADVANCING SURFACE LOW. WILL START A WINTER WEATHER
ADVISORY AT 6AM FOR JEFF/OSW/LEWIS COUNTIES WITH A 6-8 INCH MAX OF
SNOW ON THE TUG HILL.
HIGH TEMPS ON FRIDAY WILL RANGE FROM THE UPPERMOST 30S TO MID 40S
FOR WESTERN TO CENTRAL NY...THE MID 30S TO NEAR 40 FOR THE EASTERN
LAKE ONTARIO REGION AND UPPER SAINT LAWRENCE VALLEY.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
REGARDLESS OF THE UNCERTAINTY PLAGUING THE NEAR-TERM FORECAST...THE
ONE THING THAT APPEARS REASONABLY CERTAIN IS THE PROBABILITY OF
WIDESPREAD LAKE EFFECT SNOWS ACROSS WESTERN NEW YORK FRIDAY NIGHT
THROUGH MUCH OF SATURDAY. THE PROBLEMATIC SURFACE LOW WILL BE
PULLING AWAY FROM THE REGION ACROSS NORTHERN NEW ENGLAND AND
SYNOPTIC SNOWS SHOULD BE WINDING DOWN ACROSS THE NORTH COUNTRY
FRIDAY EVENING AS THE DEFORMATION BAND WEST OF THE LOW CROSSES THE
AREA.
COLDER AIR WRAPPING BEHIND THE LOW WILL FLOW ACROSS THE LAKES
FRIDAY EVENING AS 850MB TEMPS DROP TOWARDS THE -8C TO -10C RANGE
UNDER WEST/NORTHWEST FLOW AND SURFACE TEMPERATURES DROP INTO THE 20S.
WHILE THE SURFACE-850MB TEMPERATURE DIFFERENTIAL IS SOMEWHAT
MARGINAL FOR TYPICAL LAKE EFFECT EVENTS...THE LARGE SCALE SYNOPTIC
PATTERN IS CERTAINLY CONDUCIVE TO DEVELOPMENT OF LAKE EFFECT WITH A
BROAD 500MB TROUGH OVER THE REGION AND CYCLONIC FLOW AT ALL LEVELS
ALONG WITH PLENTY OF LINGERING SYNOPTIC MOISTURE THAT EXTENDS DEEP
INTO THE ATMOSPHERE. GIVEN THIS FAVORABLE SETUP...WILL GO WITH A
BROADBRUSH LES WATCH FOR ALL OF THE CWA WITH THE EXCEPTIONS OF
ONTARIO/LIVINGSTON COUNTIES WHERE CLIMATOLOGY GENERALLY RULES
AGAINST SIGNIFICANT ACCUMULATIONS. WITH THE FLOW VEERING FROM 270 TO
290/300 DEGREES...IT CURRENTLY APPEARS THAT THE MOST SIGNIFICANT
ACCUMULATIONS WILL OCCUR FROM OSWEGO/SOUTHERN LEWIS DOWN TO EASTERN
WAYNE COUNTIES OFF OF LAKE ONTARIO AND FROM SOUTHERN ERIE DOWN INTO
THE SOUTHERN TIER OFF OF LAKE ERIE. THESE AREAS HAVE THE STRONGEST
POSSIBILITY OF SEEING WARNING LEVEL SNOWS FRIDAY NIGHT THROUGH
SATURDAY NIGHT...HOWEVER GIVEN THE POTENTIAL FOR THE DEVELOPMENT OF
A LAKE HURON/GEORGIAN BAY CONNECTION...CANNOT RULE OUT AT LEAST
ADVISORY LEVEL SNOWS FROM NORTHERN ERIE COUNTY OVER TO ROCHESTER.
IN ADDITION TO DEVELOPING LAKE EFFECT SNOWS...THE ABOVE-MENTIONED
COLD ADVECTION AND TIGHT PRESSURE GRADIENT BEHIND THE EXITING
SURFACE LOW WILL ALSO BRING A PERIOD OF GUSTY WINDS. MODEL GUIDANCE
SUGGESTS THAT THE STRONGEST WINDS ALOFT...AND HENCE THE
SURFACE...WILL BE ACROSS THE GENESEE VALLEY AND FINGER LAKES
REGION...CLOSEST TO THE AREA OF GREATEST DOWNWARD MOMENTUM. BUFKIT
PROFILES INDICATE THAT WIND GUSTS MAY EXCEED ADVISORY CRITERIA WITH
MAX GUSTS IN THE NEIGHBORHOOD OF 40-50KTS ACROSS THE AFOREMENTIONED
AREAS WITH SLIGHTLY LOWER GUSTS TO THE NORTH AND WEST...MORE LIKE
35-45KTS. GIVEN THE UNCERTAINTY IN THE EXACT TRACK OF THE LOW AND
THE FACT THAT WE ARE TALKING ABOUT AN ADVISORY THAT STRADDLES THE
END OF THE THIRD INTO THE FOURTH FORECAST PERIODS...WILL HOLD OFF ON
ISSUING ANY WIND ADVISORIES FOR NOW AND LEAVE THAT TO THE NEXT SHIFT
TO MAKE THE FINAL CALL ON...WHEN THERE WILL HOPEFULLY BE GREATER
CONFIDENCE.
AFTER A WINTRY DAY SATURDAY WITH HIGHS RIGHT AROUND 30
DEGREES...MUCH MORE WHAT ONE WOULD EXPECT FOR MID TO LATE FEBRUARY.
...LAKE EFFECT SNOWS SHOULD WIND DOWN SATURDAY NIGHT AS RIDGING ALOFT
AND AT THE SURFACE BUILDS ACROSS THE EASTERN GREAT LAKES WITH ANY
LINGERING FLURRIES ENDING BY SUNDAY MORNING AS FLOW TURNS SOUTHERLY.
THIS SHOULD RESULT IN FAIRLY PLEASANT DAY ON SUNDAY WITH AT LEAST
THE AREAS WEST OF THE GENESEE VALLEY SEEING A FAIR AMOUNT OF
SUNSHINE. WARM ADVECTION ALOFT AHEAD OF A CLIPPER LOW OVER THE UPPER
MIDWEST WILL RESULT IN MID-LEVEL CLOUDINESS EAST OF THE GENESEE
VALLEY. LOOK FOR TEMPERATURES TO RUN RIGHT AROUND NORMAL FOR THIS
TIME OF YEAR SUNDAY AND SUNDAY NIGHT AS THE COLD AIR IN PLACE SLOWLY
RETREATS TO THE NORTH.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
LOOK FOR A WARM AND DRY START TO THE WEEK AS A CLIPPER LOW SLIDES
FROM THE UPPER GREAT LAKES INTO QUEBEC PLACING WESTERN NEW YORK
FIRMLY IN THE WARM SECTOR OF THE LOW UNDER BROAD SOUTHERLY FLOW. ANY
ISENTROPICALLY INDUCED PRECIP WILL OCCUR FAR TO OUR NORTH IN
CANADA...RESULTING IN DRY DAY WITH A DECENT AMOUNT OF SUNSHINE
ACROSS THE AREA HELPING HIGHS TO CLIMB WELL INTO THE 40S.
MODEL CONSENSUS SUGGESTS A DRY NIGHT TUESDAY NIGHT...HOWEVER THERE
ARE SOME DISPARITIES IN THE TEMPERATURE FORECAST BASED ON
DIFFERENCES IN THE TIMING/LOCATION OF A SURFACE LOW PROGGED TO FORM
OVER THE GREAT PLAINS SOMETIME BETWEEN MONDAY NIGHT AND TUESDAY
AFTERNOON. THE GFS IS MUCH FASTER IN DEVELOPING BROAD WARM ADVECTION
ACROSS THE OHIO VALLEY/LOWER GREAT LAKES MONDAY NIGHT AS OPPOSED TO
THE ECMWF THAT ALLOWS COLDER AIR TO FLOW ACROSS THE AREA BEFORE WARM
ADVECTION KICKS IN TUESDAY NIGHT. THIS PRESENTS A VERY SIMILAR
CONUNDRUM TO THE ONE PLAYING OUT RIGHT NOW FOR TONIGHT/S FORECAST
AND GIVEN HOW FAR OUT WE ARE TALKING ABOUT...CHANGES WILL BE VERY
MINOR...STICKING WITH SLIGHTLY ABOVE NORMAL LOWS IN THE UPPER 20S
MONDAY NIGHT.
THE AFOREMENTIONED LOW THAT DEVELOPS OVER THE MIDWEST DURING THE
EARLY PART OF NEST WEEK AND TRACKS ACROSS THE LOWER GREAT LAKES AND
EVENTUALLY ACROSS NEW YORK STATE SOMETIME DURING THE MIDDLE OF NEXT
WEEK WITH TIMING DEPENDENT ON WHICH MODEL YOU GO WITH. GIVEN THE
UNCERTAINTY ALREADY DISCUSSED AND THE LACK OF CONFIDENCE IN ANY ONE
SOLUTION...THE GRIDS FOR TUESDAY AND WEDNESDAY WILL FEATURE
BROAD-BRUSHED CHANCE POPS WITH RUNNING ABOUT 5 DEGREES ABOVE
NORMAL...WHICH IS APPROPRIATE GIVEN THE TRENDS THIS SEASON.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
VFR CONDITIONS LOWERING TO IFR/LIFR BY MORNING AS AN AREA OF LOW
PRESSURE BRINGS LOWERING CIGS AND SNOW OVERNIGHT. IR SATELLITE AND
OBS SHOWING MID AND HIGH CLOUDS IN PLACE OVER THE FORECAST AREA
AHEAD OF THE STORM SYSTEM. CIGS/VIS EXPECTED TO RAPIDLY LOWER TO
IFR/LIFR AFTER 07Z-09Z WITH ON SET OF INTENSE BAND OF RAIN SHIFTING
NORTH INTO NY AND CHANGING TO SNOW. SNOW WILL BE HEAVY AT TIMES OVER
THE SOUTHERN TIER AND CHAUTAUQUA RIDGE. RADAR MOSAIC PICKING UP
STRONG PRECIP ECHOES NEAR THE NY/PA BORDER WHICH WILL TRANSLATE INTO
THE BAND OF HEAVY SNOW AS IT SHIFT NORTHWARD. A TRANSITION TO RAIN
IS EXPECTED BY MID MORNING ACROSS WESTERN NY INTO THE AFTERNOON AS
THE STORM CENTER MOVES NORTH OF LAKE ONTARIO. KART WILL SEE A LATER
ARRIVAL OF SNOW...11Z-12Z AND LATER CHANGE TO RAIN IF AT ALL. SNOW
WILL REDEVELOP ON THE BACK SIDE OF THE STORM SYSTEM THIS EVENING
AS COLD FRONT PASSES EAST THEN LAKE SNOW BANDS WILL SET UP INTO
TONIGHT.
OUTLOOK...
SATURDAY...VFR...WITH IFR/MVFR IN SCATTERED SNOW SHOWERS AND AREAS
OF LAKE EFFECT SNOW EAST OF THE LAKES.
SUNDAY...VFR...SCTD LAKE EFFECT SNOW SOUTHEASTERN LAKE ONTARIO.
MONDAY...VFR.
&&
.MARINE...
LOW PRESSURE OVER THE LOWER OHIO VALLEY WILL DEEPEN AND LIFT
NORTHEASTWARD TOWARD THE LOWER LAKES BY FRIDAY AFTERNOON. THIS LOW
WILL CONTINUE ON ACROSS LAKE ERIE AND WESTERN LAKE ONTARIO...RAISING
WINDS AND WAVES. LATEST MODEL DATA INDICATES GALE FORCE WINDS
POSSIBLE FRIDAY EVENING INTO FRIDAY NIGHT ACROSS LAKE ERIE SO A GALE
WATCH HAS BEEN HOISTED. SMALL CRAFT ADVISORIES IN EFFECT EARLIER
FRIDAY AFTERNOON ACROSS LAKE ERIE PRE-GALE AND ACROSS THE LAKE
ONTARIO NEAR SHORES FRIDAY NIGHT AND SATURDAY AS THE STORM SYSTEM
SHIFTS FROM LAKE ONTARIO UP THE ST. LAWRENCE. HIGH PRESSURE WILL
FILL IN FOR SUNDAY WITH WINDS AND WAVES RELAXING.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW WATCH FROM FRIDAY EVENING THROUGH SUNDAY
MORNING FOR NYZ001>008-010>012-019>021-085.
WINTER WEATHER ADVISORY FROM 6 AM TO 7 PM EST FRIDAY FOR
NYZ006>008.
WINTER WEATHER ADVISORY UNTIL 7 PM EST FRIDAY FOR NYZ010>014-
019>021-085.
MARINE...GALE WATCH FROM FRIDAY AFTERNOON THROUGH LATE FRIDAY NIGHT FOR
LEZ040-041.
SMALL CRAFT ADVISORY FROM NOON TO 4 PM EST FRIDAY FOR
LEZ040-041.
SMALL CRAFT ADVISORY FROM 6 PM FRIDAY TO 6 AM EST
SUNDAY FOR LOZ043>045.
SMALL CRAFT ADVISORY FROM 5 AM FRIDAY TO 6 AM EST SUNDAY
FOR LOZ042.
&&
$$
SYNOPSIS...WCH
NEAR TERM...SMITH/WCH
SHORT TERM...WOOD
LONG TERM...WOOD
AVIATION...SMITH
MARINE...SMITH
AREA FORECAST DISCUSSION
NWS NEW YORK NY
740 AM EST FRI FEB 24 2012
.SYNOPSIS...
A POTENT STORM SYSTEM APPROACHES FROM THE WEST TODAY...WITH AN
ASSOCIATED COASTAL LOW TRACKING JUST TO OUR SOUTH THIS
EVENING...THEN ON NORTHEAST INTO THE CANADIAN MARITIMES THROUGH
SATURDAY. LOW PRESSURE NORTHEAST OF THE AREA DEPARTS SATURDAY
NIGHT...THEN HIGH PRESSURE BUILDS THROUGH THE REGION OVER THE
START OF THE NEW WEEK. LOW PRESSURE PASSING TO THE NORTH WILL DRAG
A WARM FRONT THROUGH THE REGION LATE MONDAY...FOLLOWED BY A COLD
FRONT MONDAY NIGHT. HIGH PRESSURE BRIEFLY RETURNS ON
TUESDAY...FOLLOWED BY A STORM SYSTEM FOR THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SNOW HAS CHANGED OVER TO RAIN ACROSS THE CWA...SO WILL GO AHEAD
AND UPDATE THE FORECAST TO REMOVE MENTION OF SNOW/SLEET...AND WILL
CARRY PLAIN RAIN. WILL CANCEL THE WINTER WEATHER ADVISORY THAT WAS
IN EFFECT FOR CT.
OTHERWISE...850 WARM FRONT LIFTS TO OUR NORTH BY MIDDAY...WITH
LIGHT RAIN/DRIZZLE IN ITS WAKE. SHOWERS MOVE INTO FAR WESTERN
ZONES LATE THIS AFTERNOON AHEAD OF AN OCCLUDED FRONT.
EXPECT THE SURFACE WARM FRONT EXPECTED TO STAY TO THE S OF LONG
ISLAND TODAY PER NAM/SREF/ECMWF WHICH GENERALLY PERFORM BETTER IN
THESE SITUATIONS INVOLVING A RETREATING DAMMING HIGH WITH SOME
CONFLUENCE ALOFT OVER THE CANADIAN MARITIMES TO SUPPORT IT.
AS A RESULT...WENT WITH A BLEND OF COOLER MET GUIDANCE AND NAM
2-METER TEMPERATURES FOR HIGHS...BUT NOT AS COLD AS HRRR 2-METER
TEMPERATURES. EXPECT HIGHS IN THE UPPER 30S ACROSS NORTHERN
INTERIOR ZONES TO LOW-MID 40S ACROSS LONG ISLAND AND THE NYC METRO.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
FOR TIMING THIS SYSTEM BLENDED THE NAM/ECMWF/CMC-GLOBAL/SREF.
EXPECT PRECIPITATION TO COME TO AN END BY MIDNIGHT ACROSS WESTERN
ZONES...AND A COUPLE OF HOURS AFTER MIDNIGHT ACROSS EASTERN ZONES.
MAIN STORY TONIGHT AND SATURDAY WILL BE STRONG TO POTENTIALLY
DAMAGING GUSTY WINDS. WITH SREF SUPPORTING STRONGER GFS LOW
LEVEL/BOUNDARY LAYER WINDS BEHIND THE COLD FRONT...HAVE GONE AHEAD
AND HOISTED A HIGH WIND WATCH FROM 3Z TONIGHT-23Z SATURDAY FOR NYC
AND LONG ISLAND AND A WIND ADVISORY FOR THE REMAINDER OF THE CWA.
THIS IS BASED ON 950 HPA WINDS FORECAST TO AROUND 50 KT AND 900
WINDS FORECAST UP TO 60 KT WITH AN EXPECTED DRY ADIABATIC LAPSE
RATE UP THROUGH AT LEAST 800 HPA BY SATURDAY...WITH THE STRONGEST
WINDS IN THE LOW LEVELS FORECAST OVER NYC/LONG ISLAND. EVEN IN THE
ADVISORY AREA THERE IS THE POTENTIAL FOR SOME DOWNED TREES...BUT
THIS SHOULD BE EVEN MORE NUMEROUS IN THE HIGH WIND WATCH AREA...IF
THESE STRONGER WINDS DO MATERIALIZE.
COULD SEE SOME LAKE EFFECT SNOW/RAIN SHOWERS ACROSS FAR W ORANGE
COUNTY...SATURDAY...SO HAVE SLIGHT CHANCE POPS THERE. WHILE A
SHOWER/SPRINKLE CANNOT BE COMPLETELY RULED OUT ELSEWHERE WITH THE
PASSING OF THE 500 HPA TROUGH AXIS...NOT CONFIDENT ENOUGH TO
REFLECT IN FORECAST.
FOR LOWS TONIGHT BLENDED MAV/MET GUIDANCE WITH NAM 2-METER
TEMPERATURES...AND FOR HIGHS SATURDAY BLENDED MAV/MET GUIDANCE
WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM 800 HPA.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
LOW PRES NEAR NEW BRUNSWICK DEPARTS SATURDAY NIGHT AS HIGH PRES
OVER THE MIDWEST CONTINUES TO BUILD EAST. THE PRESSURE GRADIENT
WILL RELAX SATURDAY NIGHT...ALLOWING NW WINDS TO DIMINISH THROUGH
THE NIGHT. CAA WILL RESULT IN LOWS DROPPING INTO THE LOW TO MID
20S THROUGHOUT THE CWA. HIGH PRES MOVES EAST ON SUNDAY...THEN WILL
BE JUST SOUTH OF THE REGION SUNDAY NIGHT. HIGH TEMPS WILL BE RIGHT
AROUND NORMAL ON SUNDAY...TOPPING OFF IN THE MID 40S.
OPTIMAL RADIATIONAL COOLING CONDITIONS SET UP SUNDAY NIGHT WITH
MAINLY CLEAR SKIES AND LIGHT WINDS...AND LOWS WILL DROP INTO THE
LOWER 30S IN/AROUND NYC...BUT WILL BE IN THE LOW TO MID 20S
ELSEWHERE.
HIGH PRES MOVES EAST ON MONDAY...AND RETURN FLOW SETS UP WITH A
STRONG S-SW FLOW. WAA WILL PUSH TEMPS WELL ABOVE NORMAL WITH HIGHS
IN THE LOW TO MID 50S OVER WESTERN AREAS AND IN THE MID TO UPPER
40S OVER EASTERN AREAS. LOW PRES WILL PASS NORTH OF THE AREA LATE
MONDAY...BUT IMPACTS SHOULD BE MINIMAL AND WILL NOT MENTION
PRECIP. HIGH PRES BUILDS THROUGH THE REGION ON TUESDAY...KEEPING
WARM AND DRY CONDITIONS IN THE FORECAST.
MODELS CONTINUE TO BRING A POTENTIALLY SIGNIFICANT SYSTEM INTO THE
REGION FOR THE MIDDLE OF THE WEEK...ALTHOUGH THERE ARE TIMING AND
STRENGTH DIFFERENCES AMONG THE GUIDANCE. WILL CARRY SLIGHT CHANCE
POPS TUESDAY NIGHT AND HIGH CHANCE POPS WEDNESDAY THROUGH THURSDAY
AS THE SYSTEM WORKS ITS WAY THROUGH THE REGION. TEMPS COULD BE
COLD ENOUGH AT NIGHT TO SUPPORT SNOW OR A RAIN/SNOW MIX ACROSS
NORTHERN ZONES WHILE PRECIP WILL GENERALLY BE RAIN ACROSS SOUTHERN
ZONES. DURING THE DAY...PRECIP SHOULD BE ALL RAIN...THOUGH THIS
COULD CHANGE AS MODELS GET A BETTER HANDLE ON THE EVOLUTION OF THE
SYSTEM.
HIGHS WEDNESDAY AND THURSDAY WILL TOP OFF IN THE MID TO UPPER 40S
AND LOWS AT NIGHT WILL DROP INTO THE LOW TO MID 30S.
&&
.AVIATION /13Z FRIDAY THROUGH TUESDAY/...
IFR WITH A WARM FRONT SOUTH OF THE REGION TODAY. A DEEPENING LOW
OVER THE EASTERN GREAT LAKES THIS AFTERNOON WILL FORM A SECONDARY
LOW ALONG THE FRONT OVER OUR REGION TOWARD EVENING. THE SYSTEM`S
COLD FRONT WILL THEN SWEEP ACROSS THE AREA LATE THIS EVENING.
MOST OF THE SNOW AND LOCALIZED SLEET FOR NORTHERN SECTIONS OVERNIGHT
IS NOW MOVING OUT OF THE AREA LEANING LIGHT RAIN AND DRIZZLE. AN
AREA OF STEADIER RAIN WILL REACH THE NY METRO AROUND 9 AM...THOUGH
NOT MUCH CHANGE IN FLIGHT CATEGORY IS EXPECTED AS THE CONDITIONS
AVERAGE IFR...THERE THERE WILL BE FLUCTUATIONS. .
VFR RETURNS OVERNIGHT BEHIND THE FRONT WITH VERY STRONG GUSTY
WESTERLY WINDS.
...NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS
CAN BE FOUND AT: HTTP://WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: TIMING OF IFR ONSET IS HIGHLY UNCERTAIN...
COULD BE LATER THAN FORECAST. LOW CONFIDENCE IN WIND DIRECTION LATE
THIS AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
KJFK FCSTER COMMENTS: TIMING OF IFR ONSET IS HIGHLY UNCERTAIN...
COULD BE LATER THAN FORECAST. LOW CONFIDENCE IN WIND DIRECTION LATER
THIS AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
KLGA FCSTER COMMENTS: BRIEF IMPROVEMENT IN CIG POSSIBLE THIS
MORNING. LOW CONFIDENCE IN WIND DIRECTION LATER THIS AFTERNOON GIVEN
LOW PRESSURE TRACK UNCERTAINTY.
KTEB FCSTER COMMENTS: A LOT OF VARIABILITY IN CIG AND VSBY TODAY
THIS AMENDMENTS ARE EXPECTED. LOW CONFIDENCE IN WIND DIRECTION
LATER THIS AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
KHPN FCSTER COMMENTS: IFR CIG MAY IMPROVE TO MARGINAL OR POSSIBLY
HIGHER. LOW CONFIDENCE IN WIND DIRECTION LATER THIS AFTERNOON GIVEN
LOW PRESSURE TRACK UNCERTAINTY.
KISP FCSTER COMMENTS: A LOT OF VARIABILITY IN CIG AND VSBY TODAY
THIS AMENDMENTS ARE EXPECTED. LOW CONFIDENCE IN WIND DIRECTION LATER
THIS AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
OUTLOOK FOR 12Z SAT THROUGH TUE...
.SAT...VFR. STRONG/GUSTY W-NW FLOW. 35 TO 40 KT GUSTS
POSSIBLE...THEN GRADUALLY DIMINISHING TOWARD EVENING.
.SUN-TUE...VFR.
&&
.MARINE...
MAIN CHANGES THIS UPDATE WAS TO REFLECT LATEST TRENDS IN
PRECIPITATION THIS MORNING. REMAINDER OF FORECAST APPEARS ON
TRACK.
WITH SCA ALREADY UP ON ALL WATERS...DID NOT WANT TO TAKE
DOWN...THOUGH GUSTS ON EASTERLY FLOW OF 10-20 KT MIGHT ONLY
OCCASIONALLY REACH SMALL CRAFT LEVELS TODAY...OVER THE OCEAN ZONES
THOUGH...SCA WARRANTED WITH SEAS ALREADY AT SCA LEVELS.
HAVE HOISTED A STORM WATCH FOR ALL WATERS TONIGHT AND SATURDAY.
THE BEST CHANCE FOR GUSTS TO STORM FORCE ON STRONG WEST WINDS IS
ACROSS SOUTHERN WATERS...THOUGH IF CURRENT FORECAST WIND DIRECTION
HOLDS...THEN CHANNELING EFFECTS IN THE SOUND COULD PROVIDE THE
EXTRA BOOST THERE.
THE TIMING FOR THE STRONGEST WIND GUSTS WILL BE LATE TONIGHT WHEN
THE STRONGEST WINDS PASS AT 900 HPA (AROUND 60 KT)...AND AGAIN
FROM LATE SATURDAY MORNING INTO SATURDAY AFTERNOON...WITH THE
POTENTIAL TO MIX DOWN 50-55 KT WINDS AROUND 800 HPA. THESE WINDS
SHOULD BUILD SEAS ON THE OCEAN TO 6 TO 13 FT AND ON THE SOUND TO
4-8 FT BY SATURDAY MORNING.
GALE FORCE WINDS WILL DIMINISH TO SMALL CRAFT ADVISORY LEVELS ON THE
WATERS FROM WEST TO EAST SATURDAY NIGHT...THEN CONDITIONS GRADUALLY
SUBSIDE TO SUB-ADVISORY LEVELS THROUGH SUNDAY AFTERNOON.
HIGH PRES BUILDS THROUGH THE WATERS FOR THE START OF THE NEW WEEK.
WINDS/SEAS SHOULD REMAIN BELOW SCA LEVELS...THOUGH SEAS MAY BRIEFLY
BUILD TO 3-5 FT ON THE EASTERN OCEAN WATERS MONDAY EVENING AS WEAK
LOW PRES PASSES EAST OF THE WATERS.
&&
.HYDROLOGY...
A STORM TOTAL LIQUID EQUIVALENT RAINFALL OF 1/2 TO 3/4 INCH IS
FORECAST THROUGH THIS EVENING. OTHERWISE...NO SIGNIFICANT PRECIP
IS EXPECTED UNTIL THE MIDDLE OF NEXT WEEK.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WIND ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST SATURDAY FOR
CTZ005>012.
NY...HIGH WIND WATCH FROM THIS EVENING THROUGH SATURDAY AFTERNOON
FOR NYZ072>075-078>081-176>179.
WIND ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST SATURDAY FOR
NYZ067>071.
NJ... WIND ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST SATURDAY FOR
NJZ002-004-006-103>108.
MARINE...STORM WATCH FROM 6 PM EST THIS EVENING THROUGH SATURDAY
AFTERNOON FOR ANZ330-335-338-340-345-350-353-355.
SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ330-
335-338-340-345-350-353-355.
&&
$$
SYNOPSIS...MALOIT/MPS
NEAR TERM...MALOIT/MPS
SHORT TERM...MALOIT
LONG TERM...MPS
AVIATION...MAS/JST
MARINE...MALOIT/MPS
HYDROLOGY...MALOIT/MPS
AREA FORECAST DISCUSSION
NWS NEW YORK NY
702 AM EST FRI FEB 24 2012
.SYNOPSIS...
A POTENT STORM SYSTEM APPROACHES FROM THE WEST TODAY...WITH AN
ASSOCIATED COASTAL LOW TRACKING JUST TO OUR SOUTH THIS
EVENING...THEN ON NORTHEAST INTO THE CANADIAN MARITIMES THROUGH
SATURDAY. LOW PRESSURE NORTHEAST OF THE AREA DEPARTS SATURDAY
NIGHT...THEN HIGH PRESSURE BUILDS THROUGH THE REGION OVER THE
START OF THE NEW WEEK. LOW PRESSURE PASSING TO THE NORTH WILL DRAG
A WARM FRONT THROUGH THE REGION LATE MONDAY...FOLLOWED BY A COLD
FRONT MONDAY NIGHT. HIGH PRESSURE BRIEFLY RETURNS ON
TUESDAY...FOLLOWED BY A STORM SYSTEM FOR THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE AREA OF LIGHT TO MODERATE SNOW THAT WAS OVER CONNECTICUT HAS
MOVED EAST TOWARD CAPE COD. ANOTHER BATCH OF RAIN OR MIXED PRECIP
OVER EASTERN LONG ISLAND SOUND AND THE FORKS WILL TRACK EAST OF
THE AREA OVER THE NEXT HOUR OR TWO.
OTHERWISE...APPEARS THERE WILL BE A BIT OF A LULL BEFORE THE NEXT
BATCH OF PRECIPITATION ARRIVES FROM THE MASON-DIXON LINE. SO HAVE
CHANGED WORDING TO PERIODS OF RAIN/SNOW/SLEET AS APPLICABLE.
EXPECT ALL PRECIPITATION TO CHANGE TO ALL RAIN BY MID MORNING FROM
S TO N AS WARMER AIR MOVES IN ALOFT.
850 WARM FRONT LIFTS TO OUR NORTH BY MIDDAY...WITH LIGHT
RAIN/DRIZZLE IN ITS WAKE. SHOWERS MOVE INTO FAR WESTERN ZONES LATE
THIS AFTERNOON AHEAD OF AN OCCLUDED FRONT.
EXPECT THE SURFACE WARM FRONT EXPECTED TO STAY TO THE S OF LONG
ISLAND TODAY PER NAM/SREF/ECMWF WHICH GENERALLY PERFORM BETTER IN
THESE SITUATIONS INVOLVING A RETREATING DAMMING HIGH WITH SOME
CONFLUENCE ALOFT OVER THE CANADIAN MARITIMES TO SUPPORT IT.
AS A RESULT...WENT WITH A BLEND OF COOLER MET GUIDANCE AND NAM
2-METER TEMPERATURES FOR HIGHS...BUT NOT AS COLD AS HRRR 2-METER
TEMPERATURES. EXPECT HIGHS IN THE UPPER 30S ACROSS NORTHERN
INTERIOR ZONES TO LOW-MID 40S ACROSS LONG ISLAND AND THE NYC METRO.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
FOR TIMING THIS SYSTEM BLENDED THE NAM/ECMWF/CMC-GLOBAL/SREF.
EXPECT PRECIPITATION TO COME TO AN END BY MIDNIGHT ACROSS WESTERN
ZONES...AND A COUPLE OF HOURS AFTER MIDNIGHT ACROSS EASTERN ZONES.
MAIN STORY TONIGHT AND SATURDAY WILL BE STRONG TO POTENTIALLY
DAMAGING GUSTY WINDS. WITH SREF SUPPORTING STRONGER GFS LOW
LEVEL/BOUNDARY LAYER WINDS BEHIND THE COLD FRONT...HAVE GONE AHEAD
AND HOISTED A HIGH WIND WATCH FROM 3Z TONIGHT-23Z SATURDAY FOR NYC
AND LONG ISLAND AND A WIND ADVISORY FOR THE REMAINDER OF THE CWA.
THIS IS BASED ON 950 HPA WINDS FORECAST TO AROUND 50 KT AND 900
WINDS FORECAST UP TO 60 KT WITH AN EXPECTED DRY ADIABATIC LAPSE
RATE UP THROUGH AT LEAST 800 HPA BY SATURDAY...WITH THE STRONGEST
WINDS IN THE LOW LEVELS FORECAST OVER NYC/LONG ISLAND. EVEN IN THE
ADVISORY AREA THERE IS THE POTENTIAL FOR SOME DOWNED TREES...BUT
THIS SHOULD BE EVEN MORE NUMEROUS IN THE HIGH WIND WATCH AREA...IF
THESE STRONGER WINDS DO MATERIALIZE.
COULD SEE SOME LAKE EFFECT SNOW/RAIN SHOWERS ACROSS FAR W ORANGE
COUNTY...SATURDAY...SO HAVE SLIGHT CHANCE POPS THERE. WHILE A
SHOWER/SPRINKLE CANNOT BE COMPLETELY RULED OUT ELSEWHERE WITH THE
PASSING OF THE 500 HPA TROUGH AXIS...NOT CONFIDENT ENOUGH TO
REFLECT IN FORECAST.
FOR LOWS TONIGHT BLENDED MAV/MET GUIDANCE WITH NAM 2-METER
TEMPERATURES...AND FOR HIGHS SATURDAY BLENDED MAV/MET GUIDANCE
WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM 800 HPA.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
LOW PRES NEAR NEW BRUNSWICK DEPARTS SATURDAY NIGHT AS HIGH PRES OVER
THE MIDWEST CONTINUES TO BUILD EAST. THE PRESSURE GRADIENT WILL
RELAX SATURDAY NIGHT...ALLOWING NW WINDS TO DIMINISH THROUGH THE
NIGHT. CAA WILL RESULT IN LOWS DROPPING INTO THE LOW TO MID 20S
THROUGHOUT THE CWA. HIGH PRES MOVES EAST ON SUNDAY...THEN WILL BE
JUST SOUTH OF THE REGION SUNDAY NIGHT. HIGH TEMPS WILL BE RIGHT
AROUND NORMAL ON SUNDAY...TOPPING OFF IN THE MID 40S.
OPTIMAL RADIATIONAL COOLING CONDITIONS SET UP SUNDAY NIGHT WITH
MAINLY CLEAR SKIES AND LIGHT WINDS...AND LOWS WILL DROP INTO THE
LOWER 30S IN/AROUND NYC...BUT WILL BE IN THE LOW TO MID 20S
ELSEWHERE.
HIGH PRES MOVES EAST ON MONDAY...AND RETURN FLOW SETS UP WITH A
STRONG S-SW FLOW. WAA WILL PUSH TEMPS WELL ABOVE NORMAL WITH HIGHS
IN THE LOW TO MID 50S OVER WESTERN AREAS AND IN THE MID TO UPPER 40S
OVER EASTERN AREAS. LOW PRES WILL PASS NORTH OF THE AREA LATE
MONDAY...BUT IMPACTS SHOULD BE MINIMAL AND WILL NOT MENTION PRECIP.
HIGH PRES BUILDS THROUGH THE REGION ON TUESDAY...KEEPING WARM AND
DRY CONDITIONS IN THE FORECAST.
MODELS CONTINUE TO BRING A POTENTIALLY SIGNIFICANT SYSTEM INTO THE
REGION FOR THE MIDDLE OF THE WEEK...ALTHOUGH THERE ARE TIMING AND
STRENGTH DIFFERENCES AMONG THE GUIDANCE. WILL CARRY SLIGHT CHANCE
POPS TUESDAY NIGHT AND HIGH CHANCE POPS WEDNESDAY THROUGH THURSDAY
AS THE SYSTEM WORKS ITS WAY THROUGH THE REGION. TEMPS COULD BE COLD
ENOUGH AT NIGHT TO SUPPORT SNOW OR A RAIN/SNOW MIX ACROSS NORTHERN
ZONES WHILE PRECIP WILL GENERALLY BE RAIN ACROSS SOUTHERN ZONES.
DURING THE DAY...PRECIP SHOULD BE ALL RAIN...THOUGH THIS COULD
CHANGE AS MODELS GET A BETTER HANDLE ON THE EVOLUTION OF THE SYSTEM.
HIGHS WEDNESDAY AND THURSDAY WILL TOP OFF IN THE MID TO UPPER 40S
AND LOWS AT NIGHT WILL DROP INTO THE LOW TO MID 30S.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
IFR WITH A WARM FRONT SOUTH OF THE REGION TODAY. A DEEPENING LOW
OVER THE EASTERN GREAT LAKES THIS AFTERNOON WILL FORM A SECONDARY
LOW ALONG THE FRONT OVER OUR REGION TOWARD EVENING. THE SYSTEM`S
COLD FRONT WILL THEN SWEEP ACROSS THE AREA LATE THIS EVENING.
MOST OF THE SNOW AND LOCALIZED SLEET FOR NORTHERN SECTIONS OVERNIGHT
IS NOW MOVING OUT OF THE AREA LEANING LIGHT RAIN AND DRIZZLE. AN
AREA OF STEADIER RAIN WILL REACH THE NY METRO AROUND 9 AM...THOUGH
NOT MUCH CHANGE IN FLIGHT CATEGORY IS EXPECTED AS THE CONDITIONS
AVERAGE IFR...THERE THERE WILL BE FLUCTUATIONS. .
VFR RETURNS OVERNIGHT BEHIND THE FRONT WITH VERY STRONG GUSTY
WESTERLY WINDS.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: TIMING OF IFR ONSET IS HIGHLY UNCERTAIN...
COULD BE LATER THAN FORECAST. LOW CONFIDENCE IN WIND DIRECTION LATE
THIS AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
KJFK FCSTER COMMENTS: TIMING OF IFR ONSET IS HIGHLY UNCERTAIN...
COULD BE LATER THAN FORECAST. LOW CONFIDENCE IN WIND DIRECTION LATER
THIS AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
KLGA FCSTER COMMENTS: BRIEF IMPROVEMENT IN CIG POSSIBLE THIS
MORNING. LOW CONFIDENCE IN WIND DIRECTION LATER THIS AFTERNOON GIVEN
LOW PRESSURE TRACK UNCERTAINTY.
KTEB FCSTER COMMENTS: A LOT OF VARIABILITY IN CIG AND VSBY TODAY
THIS AMENDMENTS ARE EXPECTED. LOW CONFIDENCE IN WIND DIRECTION
LATER THIS AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
KHPN FCSTER COMMENTS: IFR CIG MAY IMPROVE TO MARGINAL OR POSSIBLY
HIGHER. LOW CONFIDENCE IN WIND DIRECTION LATER THIS AFTERNOON GIVEN
LOW PRESSURE TRACK UNCERTAINTY.
KISP FCSTER COMMENTS: A LOT OF VARIABILITY IN CIG AND VSBY TODAY
THIS AMENDMENTS ARE EXPECTED. LOW CONFIDENCE IN WIND DIRECTION LATER
THIS AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
OUTLOOK FOR 12Z SAT THROUGH TUE...
.SAT...VFR. STRONG/GUSTY W-NW FLOW. 35 TO 40 KT GUSTS
POSSIBLE...THEN GRADUALLY DIMINISHING TOWARD EVENING.
.SUN-TUE...VFR.
&&
.MARINE...
MAIN CHANGES THIS UPDATE WAS TO REFLECT LATEST TRENDS IN
PRECIPITATION THIS MORNING. REMAINDER OF FORECAST APPEARS ON
TRACK.
WITH SCA ALREADY UP ON ALL WATERS...DID NOT WANT TO TAKE
DOWN...THOUGH GUSTS ON EASTERLY FLOW OF 10-20 KT MIGHT ONLY
OCCASIONALLY REACH SMALL CRAFT LEVELS TODAY...OVER THE OCEAN ZONES
THOUGH...SCA WARRANTED WITH SEAS ALREADY AT SCA LEVELS.
HAVE HOISTED A STORM WATCH FOR ALL WATERS TONIGHT AND SATURDAY.
THE BEST CHANCE FOR GUSTS TO STORM FORCE ON STRONG WEST WINDS IS
ACROSS SOUTHERN WATERS...THOUGH IF CURRENT FORECAST WIND DIRECTION
HOLDS...THEN CHANNELING EFFECTS IN THE SOUND COULD PROVIDE THE
EXTRA BOOST THERE.
THE TIMING FOR THE STRONGEST WIND GUSTS WILL BE LATE TONIGHT WHEN
THE STRONGEST WINDS PASS AT 900 HPA (AROUND 60 KT)...AND AGAIN
FROM LATE SATURDAY MORNING INTO SATURDAY AFTERNOON...WITH THE
POTENTIAL TO MIX DOWN 50-55 KT WINDS AROUND 800 HPA. THESE WINDS
SHOULD BUILD SEAS ON THE OCEAN TO 6 TO 13 FT AND ON THE SOUND TO
4-8 FT BY SATURDAY MORNING.
GALE FORCE WINDS WILL DIMINISH TO SMALL CRAFT ADVISORY LEVELS ON THE
WATERS FROM WEST TO EAST SATURDAY NIGHT...THEN CONDITIONS GRADUALLY
SUBSIDE TO SUB-ADVISORY LEVELS THROUGH SUNDAY AFTERNOON.
HIGH PRES BUILDS THROUGH THE WATERS FOR THE START OF THE NEW WEEK.
WINDS/SEAS SHOULD REMAIN BELOW SCA LEVELS...THOUGH SEAS MAY BRIEFLY
BUILD TO 3-5 FT ON THE EASTERN OCEAN WATERS MONDAY EVENING AS WEAK
LOW PRES PASSES EAST OF THE WATERS.
&&
.HYDROLOGY...
A STORM TOTAL LIQUID EQUIVALENT RAINFALL OF 1/2 TO 3/4 INCH IS
FORECAST THROUGH THIS EVENING. OTHERWISE...NO SIGNIFICANT PRECIP
IS EXPECTED UNTIL THE MIDDLE OF NEXT WEEK.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WIND ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST SATURDAY FOR
CTZ005>012.
WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
CTZ005>012.
NY...HIGH WIND WATCH FROM THIS EVENING THROUGH SATURDAY AFTERNOON
FOR NYZ072>075-078>081-176>179.
WIND ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST SATURDAY FOR
NYZ067>071.
NJ... WIND ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST SATURDAY FOR
NJZ002-004-006-103>108.
MARINE...STORM WATCH FROM 6 PM EST THIS EVENING THROUGH SATURDAY
AFTERNOON FOR ANZ330-335-338-340-345-350-353-355.
SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ330-
335-338-340-345-350-353-355.
&&
$$
SYNOPSIS...MALOIT/MPS
NEAR TERM...MALOIT
SHORT TERM...MALOIT
LONG TERM...MPS
AVIATION...MAS/JST
MARINE...MALOIT/MPS
HYDROLOGY...MALOIT/MPS
AREA FORECAST DISCUSSION
NWS ALBANY NY
648 AM EST FRI FEB 24 2012
.SYNOPSIS...
A COMPLEX LOW PRESSURE SYSTEM WILL AFFECT THE REGION THROUGH TONIGHT
WITH SNOW AND RAIN. SOME LINGERING SNOW SHOWERS ALONG WITH WINDY
CONDITIONS WILL OCCUR IN THE WAKE OF THE STORM ON SATURDAY. FAIR AND
CHILLY CONDITIONS WILL RETURN FOR SUNDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 500 AM...RADAR SHOWS THAT THE RUC SHORT TERM MODEL APPEARS TO
BE CORRECT THAT THE HEAVY BAND OF SNOW OVER THE SOUTHERN PART OF THE
FORECAST AREA WILL EXIT THE REGION TO THE EAST EARLY THIS MORNING...
AND ONLY RELATIVELY LIGHT SNOW WILL LIFT NORTH ACROSS THE REST OF
THE REGION. THIS WILL RESULT IN A LULL IN THE PCPN FOR MUCH OF THE
MORNING AND INTO EARLY THIS AFTERNOON...BEFORE ANOTHER ROUND OF
SIGNIFICANT PCPN MOVES IN LATER THIS AFTERNOON AHEAD OF THE FRONTAL
BOUNDARY ASSOCIATED WITH THE LOW MOVING THROUGH THE EASTERN GREAT
LAKES.
AS A RESULT...WITH NO WIDESPREAD SIGNIFICANT SNOW EXPECTED TO MAKE
IT NORTH OF GREENE...COLUMBIA AND BERKSHIRE COUNTY EARLY THIS
MORNING...DECIDED TO DROP THE WINTER WEATHER ADVISORY FOR THE
SCHOHARIE AND MOHAWK VALLEYS...THE HELDERBERGS AND THE NORTHERN
TACONICS. FURTHER NORTH SNOW WILL BE LIGHT THIS MORNING...BUT IT MAY
STILL BE COLD ENOUGH FOR ACCUMULATING SNOW THIS AFTERNOON WHEN THE
NEXT ROUND OF PCPN ARRIVES...SO THE WINTER WEATHER ADVISORY
CONTINUES ACROSS NORTHERN AREAS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
AS STATED IN THE NEAR TERM DISCUSSION...ANOTHER ROUND OF SIGNIFICANT
PCPN WILL MOVE THROUGH THE REGION THIS EVENING AHEAD OF A FRONTAL
BOUNDARY. BY THAT TIME MOST AREAS WILL BE TOO WARM FOR SNOW
RAIN...BUT AREAS FROM THE ADIRONDACKS TO LAKE GEORGE AND SOUTHERN
VERMONT COULD STILL BE COLD ENOUGH TO GET SOME SNOW FROM THE NEXT
ROUND OF PCPN...SO THE WINTER WEATHER ADVISORIES REMAIN IN EFFECT
THERE. BEHIND THE FRONTAL BOUNDARY STRONG WESTERLY WINDS AND THE
APPROACH OF THE UPPER LEVEL TROF ASSOCIATED WITH THE SURFACE LOW
WILL PRODUCE A PERIOD OF SCATTERED TO WIDESPREAD SNOW SHOWERS ACROSS
THE REGION DUE TO A COMBINATION OF UPSLOPE AND LAKE ENHANCED SNOW
ACROSS THE REGION....WITH THIS PATTERN PERSISTING WELL INTO SATURDAY
NIGHT...BUT GRADUALLY DIMINISHING WITH TIME.
BEHIND THE SURFACE LOW EXPECT STRONG WEST TO NORTHWEST WINDS LATE
FRIDAY NIGHT THROUGH SATURDAY AND A WIND ADVISORY HAS BEEN ISSUED.
HIGH PRESSURE WILL BUILD IN FOR SUNDAY WITH TRANQUIL BUT COLD
WEATHER.
LOWS FRIDAY NIGHT WILL BE BETWEEN 20 AND 30 WITH WIND GUSTS UP TO 50
MPH POSSIBLE BY LATE AT NIGHT. HIGHS SATURDAY WILL BE IN THE UPPER
20S TO LOWER 40S WITH WIND GUSTS UP TO 50 MPH POSSIBLE THROUGHOUT
THE DAY. WINDS WILL DECREASE SOMEWHAT SATURDAY NIGHT...BUT STILL
BLOW AT 10 TO 20 MPH WITH GUSTS TO 30 MPH. LIGHTER WINDS FINALLY
SUNDAY WITH GUSTS UP TO AROUND 20 MPH...BUT DECREASING EVEN FURTHER
BY LATE IN THE DAY. HIGHS WILL BE IN THE MID 20S TO THE 30S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
DETERMINISTIC...BOTH 00Z EURO AND 00Z GFS SHOW WEAK UPPER IMPULSE
MOVING NORTH OF THE AREA ON MONDAY. SOME TIMING DIFFERENCES BUT
OVERALL IMPACT WILL BE FOR CLOUDS/CHANCE POPS OVER NORTHERN THIRD OF
AREA. REST OF AREA SHOULD REMAIN PARTLY SUNNY AND DRY. AFTER
IMPULSE PASSES BY A WEAK COLD FRONT CROSSES AREA MONDAY NIGHT. COLD
ADVECTION MAY LEAD TO SOME SCATTERED LAKE EFFECT SNOW SHOWERS SO
SLT/CHC POPS NORTHWEST EARLY TUESDAY BUT RIDGING SHOULD LEAD TO
MAINLY FAIR WEATHER ACROSS AREA. BY WEDNESDAY ANOTHER STORM SYSTEM
MOVES INTO GREAT LAKES REGION AND UP SAINT LAWRENCE AND LIKE PRESENT
STORM...THIS ONE BRINGS WINTRY MIX CHANGING TO RAIN AND BACK TO SNOW
DOWNWIND OF LAKE ONTARIO AND OVER HIGHER TERRAIN. EURO A LITTLE
SLOWER BUT BY LATE THURSDAY ALL BUT FAR NORTHWEST SHOULD BE DRY WITH
LINGERING LAKE EFFECT AND UPSLOPE SNOW SHOWERS. BOTH MODELS SHOW
RIDGING BUILDING INTO THE AREA ON FRIDAY WITH FAIR WEATHER.
PROBABILISTIC...00Z GEFS ENSEMBLES SHOW HIGHEST PROBABILITY OF
PRECIP ON WEDNESDAY INTO THURSDAY. EXTENDED STATISTICAL GUIDANCE
SHOWS TEMPS AVERAGING ABOVE NORMAL ALTHOUGH SATURDAY THROUGH MONDAY
WILL BE NEAR NORMAL.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
LOW PRESSURE OVER OHIO THIS MORNING WILL MOVE UP THE SAINT LAWRENCE
VALLEY TONIGHT. A WARM FRONT WILL BRING PERIODS OF SNOW AND RAIN TO
KALB AND KGFL WHILE KPOU WILL SEE PERIODS OF RAIN. MVFR CONDITIONS
ARE EXPECTED AT THE TAF SITES MOST OF TODAY INTO THIS EVENING BEFORE
A COLD FRONT SWEEPS THROUGH. BEHIND THE FRONT SOME LIGHT SNOW OR
SNOW SHOWERS ARE POSSIBLE OVERNIGHT AT KGFL AND KALB WITH MVFR. VFR
BEHIND FRONT AT KPOU.
WINDS WILL BE EAST NORTHEAST AT 6 KTS OR LESS FRIDAY MORNING AND
EAST TO SOUTHEAST AROUND 10 KTS OR LESS FRIDAY AFTERNOON. WINDS WILL
SWITCH TO SOUTHWEST TO WEST NEAR MIDNIGHT AND BECOME GUSTY. WINDS
SATURDAY WEST TO NORTHWEST 15 TO 25 KTS WITH OCCASIONAL GUST TO 40KT.
OUTLOOK....
LATE FRI NGT...VFR/MVFR...CHC -SHSN. BECOMING WINDY.
SAT...VFR...SLIGHT CHC -SHSN. WINDY.
SAT NIGHT-SUN...VFR...DECREASING WINDS.
MON...VFR SLIGHT CHC -SHRA/-SHSN.
TUE...VFR.
&&
.HYDROLOGY...
SOME MODERATE RIVER RISES ARE POSSIBLE OVER THE SOUTHERN THIRD OF
OUR AREA TONIGHT AS RUNOFF FROM MELTING SNOW COMBINES WITH RUNOFF
FROM SOME HEAVIER DOWNPOURS AHEAD OF A COLD FRONT. SOME PONDING OF
WATER IN LOW LYING AND POOR DRAINAGE AREAS MAY SLOW THE EVENING
COMMUTE. NO LARGER RIVER FLOODING IS EXPECTED DURING THE NEXT 5 DAYS.
SOME GAGES ARE STILL BEING IMPACTED BY ICE ACROSS NORTHERN PORTIONS
OF THE HYDROLOGIC SERVICE AREA. PERSISTENT COLD TEMPERATURES THIS
WEEKEND MAY ALLOW ADDITIONAL ICE FORMATION TO OCCUR LATE SATURDAY
INTO EARLY MONDAY IN BASINS NORTH OF THE MOHAWK RIVER VALLEY.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...WIND ADVISORY FROM 1 AM TO 7 PM EST SATURDAY FOR CTZ001-013.
NY...WINTER WEATHER ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR
NYZ058-063.
WIND ADVISORY FROM 1 AM TO 7 PM EST SATURDAY FOR NYZ032-033-
038>043-047>054-058>061-063>066-082>084.
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NYZ032-
033-042-043-061-082-083.
MA...WIND ADVISORY FROM 1 AM TO 7 PM EST SATURDAY FOR MAZ001-025.
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR MAZ001-
025.
VT...WIND ADVISORY FROM 1 AM TO 7 PM EST SATURDAY FOR VTZ013>015.
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR
VTZ013>015.
&&
$$
SYNOPSIS...GJM
NEAR TERM...GJM
SHORT TERM...GJM
LONG TERM...SND
AVIATION...SND
HYDROLOGY...SND
AREA FORECAST DISCUSSION
NWS ALBANY NY
600 AM EST FRI FEB 24 2012
.SYNOPSIS...
A COMPLEX LOW PRESSURE SYSTEM WILL AFFECT THE REGION THROUGH TONIGHT
WITH SNOW AND RAIN. SOME LINGERING SNOW SHOWERS ALONG WITH WINDY
CONDITIONS WILL OCCUR IN THE WAKE OF THE STORM ON SATURDAY. FAIR AND
CHILLY CONDITIONS WILL RETURN FOR SUNDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 500 AM...RADAR SHOWS THAT THE RUC SHORT TERM MODEL APPEARS TO
BE CORRECT THAT THE HEAVY BAND OF SNOW OVER THE SOUTHERN PART OF THE
FORECAST AREA WILL EXIT THE REGION TO THE EAST EARLY THIS MORNING...
AND ONLY RELATIVELY LIGHT SNOW WILL LIFT NORTH ACROSS THE REST OF
THE REGION. THIS WILL RESULT IN A LULL IN THE PCPN FOR MUCH OF THE
MORNING AND INTO EARLY THIS AFTERNOON...BEFORE ANOTHER ROUND OF
SIGNIFICANT PCPN MOVES IN LATER THIS AFTERNOON AHEAD OF THE FRONTAL
BOUNDARY ASSOCIATED WITH THE LOW MOVING THROUGH THE EASTERN GREAT
LAKES.
AS A RESULT...WITH NO WIDESPREAD SIGNIFICANT SNOW EXPECTED TO MAKE
IT NORTH OF GREENE...COLUMBIA AND BERKSHIRE COUNTY EARLY THIS
MORNING...DECIDED TO DROP THE WINTER WEATHER ADVISORY FOR THE
SCHOHARIE AND MOHAWK VALLEYS...THE HELDERBERGS AND THE NORTHERN
TACONICS. FURTHER NORTH SNOW WILL BE LIGHT THIS MORNING...BUT IT MAY
STILL BE COLD ENOUGH FOR ACCUMULATING SNOW THIS AFTERNOON WHEN THE
NEXT ROUND OF PCPN ARRIVES...SO THE WINTER WEATHER ADVISORY
CONTINUES ACROSS NORTHERN AREAS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
AS STATED IN THE NEAR TERM DISCUSSION...ANOTHER ROUND OF SIGNIFICANT
PCPN WILL MOVE THROUGH THE REGION THIS EVENING AHEAD OF A FRONTL
BOUNDARY. BY THAT TIME MOST AREAS WILL BE TOO WARM FOR SNOW
RAIN...BUT AREAS FROM THE ADIRONDACKS TO LAKE GEORGE AND SOUTHERN
VERMONT COULD STILL BE COLD ENOUGH TO GET SOME SNOW FROM THE NEXT
ROUND OF PCPN...SO THE WINTER WEATHER ADVISORIES REMAIN IN EFFECT
THERE. BEHIND THE FRONTAL BOUNDARY STRONG WESTERLY WINDS AND THE
APPROACH OF THE UPPER LEVEL TROF ASSOCIATED WITH THE SURFACE LOW
WILL PRODUCE A PERIOD OF SCATTERED TO WIDESPREAD SNOW SHOWERS ACROSS
THE REGION DUE TO A COMBINATION OF UPSLOPE AND LAKE ENHANCED SNOW
ACROSS THE REGION....WITH THIS PATTERN PERSISTING WELL INTO SATURDAY
NIGHT...BUT GRADUALLY DIMINISHING WITH TIME.
BEHIND THE SURFACE LOW EXPECT STRONG WEST TO NORTHWEST WINDS LATE
FRIDAY NIGHT THROUGH SATURDAY AND A WIND ADVISORY HAS BEEN ISSUED.
HIGH PRESSURE WILL BUILD IN FOR SUNDAY WITH TRANQUIL BUT COLD
WEATHER.
LOWS FRIDAY NIGHT WILL BE BETWEEN 20 AND 30 WITH WIND GUSTS UP TO 50
MPH POSSIBLE BY LATE AT NIGHT. HIGHS SATURDAY WILL BE IN THE UPPER
20S TO LOWER 40S WITH WIND GUSTS UP TO 50 MPH POSSIBLE THROUGHOUT
THE DAY. WINDS WILL DECREASE SOMEWHAT SATURDAY NIGHT...BUT STILL
BLOW AT 10 TO 20 MPH WITH GUSTS TO 30 MPH. LIGHTER WINDS FINALLY
SUNDAY WITH GUSTS UP TO AROUND 20 MPH...BUT DECREASING EVEN FURTHER
BY LATE IN THE DAY. HIGHS WILL BE IN THE MID 20S TO THE 30S.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
DETERMINISTIC...BOTH 00Z EURO AND 00Z GFS SHOW WEAK UPPER IMPULSE
MOVING NORTH OF THE AREA ON MONDAY. SOME TIMING DIFFERENCES BUT
OVERALL IMPACT WILL BE FOR CLOUDS/CHANCE POPS OVER NORTHERN THIRD OF
AREA. REST OF AREA SHOULD REMAIN PARTLY SUNNY AND DRY. AFTER
IMPULSE PASSES BY A WEAK COLD FRONT CROSSES AREA MONDAY NIGHT. COLD
ADVECTION MAY LEAD TO SOME SCATTERED LAKE EFFECT SNOW SHOWERS SO
SLT/CHC POPS NORTHWEST EARLY TUESDAY BUT RIDGING SHOULD LEAD TO
MAINLY FAIR WEATHER ACROSS AREA. BY WEDNESDAY ANOTHER STORM SYSTEM
MOVES INTO GREAT LAKES REGION AND UP SAINT LAWRENCE AND LIKE PRESENT
STORM...THIS ONE BRINGS WINTRY MIX CHANGING TO RAIN AND BACK TO SNOW
DOWNWIND OF LAKE ONTARIO AND OVER HIGHER TERRAIN. EURO A LITTLE
SLOWER BUT BY LATE THURSDAY ALL BUT FAR NORTHWEST SHOULD BE DRY WITH
LINGERING LAKE EFFECT AND UPSLOPE SNOW SHOWERS. BOTH MODELS SHOW
RIDGING BUILDING INTO THE AREA ON FRIDAY WITH FAIR WEATHER.
PROBABILISTIC...00Z GEFS ENSEMBLES SHOW HIGHEST PROBABILITY OF
PRECIP ON WEDNESDAY INTO THURSDAY. EXTENDED STATISTICAL GUIDANCE
SHOWS TEMPS AVERAGING ABOVE NORMAL ALTHOUGH SATURDAY THROUGH MONDAY
WILL BE NEAR NORMAL.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
A LOW PRESSURE SYSTEM WILL APPROACH FROM THE OHIO VALLEY TONIGHT
BRINGING A WINTRY MIX WITH VFR CONDITIONS GIVING WAY TO MVFR/IFR
CONDITIONS BETWEEN 08Z AND 13Z FROM SOUTH TO NORTH. THE WINTRY MIX
IS THEN EXPECTED TO GRADUALLY CHANGE TO ALL RAIN AT THE TAF SITES
BTWN 13Z AND 18Z WITH KGFL BEING THE SLOWEST TO CHANGE TO RAIN.
MVFR/IFR CONDITIONS ARE EXPECTED AT THE TAF SITES FROM 16Z-18Z
THROUGH MOST OF THE REST OF THE TAF PERIOD EXCEPT AT KPOU WHICH
COULD BECOME VFR FOR THE LAST FEW HOURS.
WINDS WILL BE LIGHT AND VARIABLE THROUGH THE REST OF THE OVERNIGHT
AND THEN BECOME EAST NORTHEAST AT 6 KTS OR LESS FRIDAY MORNING AND
EAST TO SOUTHEAST AROUND 10 KTS OR LESS FRIDAY AFTERNOON. DEPENDING
ON THE TIMING OF A COLD FRONT PASSAGE WINDS MAY SWITCH TO SOUTHWEST
TO WEST NEAR THE END OF THE TAF PERIOD AND BECOME GUSTY.
OUTLOOK....
LATE FRI NGT...VFR/MVFR...CHC -SHSN. BECOMING WINDY.
SAT...VFR...SLIGHT CHC -SHSN. WINDY.
SAT NIGHT-SUN...VFR...DECREASING WINDS.
MON...VFR SLIGHT CHC -SHRA/-SHSN.
TUE...VFR.
&&
.HYDROLOGY...
SOME MODERATE RIVER RISES ARE POSSIBLE OVER THE SOUTHERN THIRD OF
OUR AREA TONIGHT AS RUNOFF FROM MELTING SNOW COMBINES WITH RUNOFF
FROM SOME HEAVIER DOWNPOURS AHEAD OF A COLD FRONT. SOME PONDING OF
WATER IN LOW LYING AND POOR DRAINAGE AREAS MAY SLOW THE EVENING
COMMUTE. NO LARGER RIVER FLOODING IS EXPECTED DURING THE NEXT 5 DAYS.
SOME GAGES ARE STILL BEING IMPACTED BY ICE ACROSS NORTHERN PORTIONS
OF THE HYDROLOGIC SERVICE AREA. PERSISTENT COLD TEMPERATURES THIS
WEEKEND MAY ALLOW ADDITIONAL ICE FORMATION TO OCCUR LATE SATURDAY
INTO EARLY MONDAY IN BASINS NORTH OF THE MOHAWK RIVER VALLEY.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...WIND ADVISORY FROM 1 AM TO 7 PM EST SATURDAY FOR CTZ001-013.
NY...WINTER WEATHER ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR
NYZ058-063.
WIND ADVISORY FROM 1 AM TO 7 PM EST SATURDAY FOR NYZ032-033-
038>043-047>054-058>061-063>066-082>084.
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NYZ032-
033-042-043-061-082-083.
MA...WIND ADVISORY FROM 1 AM TO 7 PM EST SATURDAY FOR MAZ001-025.
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR MAZ001-
025.
VT...WIND ADVISORY FROM 1 AM TO 7 PM EST SATURDAY FOR VTZ013>015.
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR
VTZ013>015.
&&
$$
SYNOPSIS...GJM
NEAR TERM...GJM
SHORT TERM...GJM
LONG TERM...SND
AVIATION...SND
HYDROLOGY...SND
AREA FORECAST DISCUSSION
NWS NEW YORK NY
551 AM EST FRI FEB 24 2012
.SYNOPSIS...
A POTENT STORM SYSTEM APPROACHES FROM THE WEST TODAY...WITH AN
ASSOCIATED COASTAL LOW TRACKING JUST TO OUR SOUTH THIS
EVENING...THEN ON NORTHEAST INTO THE CANADIAN MARITIMES THROUGH
SATURDAY. LOW PRESSURE NORTHEAST OF THE AREA DEPARTS SATURDAY
NIGHT...THEN HIGH PRESSURE BUILDS THROUGH THE REGION OVER THE
START OF THE NEW WEEK. LOW PRESSURE PASSING TO THE NORTH WILL DRAG
A WARM FRONT THROUGH THE REGION LATE MONDAY...FOLLOWED BY A COLD
FRONT MONDAY NIGHT. HIGH PRESSURE BRIEFLY RETURNS ON
TUESDAY...FOLLOWED BY A STORM SYSTEM FOR THE MIDDLE OF NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HAVE ANOTHER AREA OF LIGHT TO MODERATE SNOW HEADING TOWARDS CT
FROM NE NJ TO FAR NW LONG ISLAND. WITH REPORTS OF 1 TO 4" ALREADY
ACROSS SOUTHERN CT...HAVE GONE AHEAD AND ISSUED A SHORT FUSED
WINTER WEATHER ADVISORY FOR SOUTHERN CT THROUGH 10 AM.
APPEARS THERE WILL BE A BIT OF A LULL BEFORE THE NEXT BATCH OF
PRECIPITATION ARRIVES FROM THE MASON-DIXON LINE. SO HAVE CHANGED
WORDING TO PERIODS OF RAIN/SNOW/SLEET AS APPLICABLE. EXPECT ALL
PRECIPITATION TO CHANGE TO ALL RAIN BY MID MORNING FROM S TO N AS
WARMER AIR MOVES IN ALOFT.
850 WARM FRONT LIFTS TO OUR NORTH BY MIDDAY...WITH LIGHT
RAIN/DRIZZLE IN ITS WAKE. SHOWERS MOVE INTO FAR WESTERN ZONES LATE
THIS AFTERNOON AHEAD OF AN OCCLUDED FRONT.
EXPECT THE SURFACE WARM FRONT EXPECTED TO STAY TO THE S OF LONG
ISLAND TODAY PER NAM/SREF/ECMWF WHICH GENERALLY PERFORM BETTER IN
THESE SITUATIONS INVOLVING A RETREATING DAMMING HIGH WITH SOME
CONFLUENCE ALOFT OVER THE CANADIAN MARITIMES TO SUPPORT IT.
AS A RESULT...WENT WITH A BLEND OF COOLER MET GUIDANCE AND NAM
2-METER TEMPERATURES FOR HIGHS...BUT NOT AS COLD AS HRRR 2-METER
TEMPERATURES. EXPECT HIGHS IN THE UPPER 30S ACROSS NORTHERN
INTERIOR ZONES TO LOW-MID 40S ACROSS LONG ISLAND AND THE NYC METRO.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
FOR TIMING THIS SYSTEM BLENDED THE NAM/ECMWF/CMC-GLOBAL/SREF.
EXPECT PRECIPITATION TO COME TO AN END BY MIDNIGHT ACROSS WESTERN
ZONES...AND A COUPLE OF HOURS AFTER MIDNIGHT ACROSS EASTERN ZONES.
MAIN STORY TONIGHT AND SATURDAY WILL BE STRONG TO POTENTIALLY
DAMAGING GUSTY WINDS. WITH SREF SUPPORTING STRONGER GFS LOW
LEVEL/BOUNDARY LAYER WINDS BEHIND THE COLD FRONT...HAVE GONE AHEAD
AND HOISTED A HIGH WIND WATCH FROM 3Z TONIGHT-23Z SATURDAY FOR NYC
AND LONG ISLAND AND A WIND ADVISORY FOR THE REMAINDER OF THE CWA.
THIS IS BASED ON 950 HPA WINDS FORECAST TO AROUND 50 KT AND 900
WINDS FORECAST UP TO 60 KT WITH AN EXPECTED DRY ADIABATIC LAPSE
RATE UP THROUGH AT LEAST 800 HPA BY SATURDAY...WITH THE STRONGEST
WINDS IN THE LOW LEVELS FORECAST OVER NYC/LONG ISLAND. EVEN IN THE
ADVISORY AREA THERE IS THE POTENTIAL FOR SOME DOWNED TREES...BUT
THIS SHOULD BE EVEN MORE NUMEROUS IN THE HIGH WIND WATCH AREA...IF
THESE STRONGER WINDS DO MATERIALIZE.
COULD SEE SOME LAKE EFFECT SNOW/RAIN SHOWERS ACROSS FAR W ORANGE
COUNTY...SATURDAY...SO HAVE SLIGHT CHANCE POPS THERE. WHILE A
SHOWER/SPRINKLE CANNOT BE COMPLETELY RULED OUT ELSEWHERE WITH THE
PASSING OF THE 500 HPA TROUGH AXIS...NOT CONFIDENT ENOUGH TO
REFLECT IN FORECAST.
FOR LOWS TONIGHT BLENDED MAV/MET GUIDANCE WITH NAM 2-METER
TEMPERATURES...AND FOR HIGHS SATURDAY BLENDED MAV/MET GUIDANCE
WITH NAM 2-METER TEMPERATURES AND A MIX DOWN FROM 800 HPA.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
LOW PRES NEAR NEW BRUNSWICK DEPARTS SATURDAY NIGHT AS HIGH PRES OVER
THE MIDWEST CONTINUES TO BUILD EAST. THE PRESSURE GRADIENT WILL
RELAX SATURDAY NIGHT...ALLOWING NW WINDS TO DIMINISH THROUGH THE
NIGHT. CAA WILL RESULT IN LOWS DROPPING INTO THE LOW TO MID 20S
THROUGHOUT THE CWA. HIGH PRES MOVES EAST ON SUNDAY...THEN WILL BE
JUST SOUTH OF THE REGION SUNDAY NIGHT. HIGH TEMPS WILL BE RIGHT
AROUND NORMAL ON SUNDAY...TOPPING OFF IN THE MID 40S.
OPTIMAL RADIATIONAL COOLING CONDITIONS SET UP SUNDAY NIGHT WITH
MAINLY CLEAR SKIES AND LIGHT WINDS...AND LOWS WILL DROP INTO THE
LOWER 30S IN/AROUND NYC...BUT WILL BE IN THE LOW TO MID 20S
ELSEWHERE.
HIGH PRES MOVES EAST ON MONDAY...AND RETURN FLOW SETS UP WITH A
STRONG S-SW FLOW. WAA WILL PUSH TEMPS WELL ABOVE NORMAL WITH HIGHS
IN THE LOW TO MID 50S OVER WESTERN AREAS AND IN THE MID TO UPPER 40S
OVER EASTERN AREAS. LOW PRES WILL PASS NORTH OF THE AREA LATE
MONDAY...BUT IMPACTS SHOULD BE MINIMAL AND WILL NOT MENTION PRECIP.
HIGH PRES BUILDS THROUGH THE REGION ON TUESDAY...KEEPING WARM AND
DRY CONDITIONS IN THE FORECAST.
MODELS CONTINUE TO BRING A POTENTIALLY SIGNIFICANT SYSTEM INTO THE
REGION FOR THE MIDDLE OF THE WEEK...ALTHOUGH THERE ARE TIMING AND
STRENGTH DIFFERENCES AMONG THE GUIDANCE. WILL CARRY SLIGHT CHANCE
POPS TUESDAY NIGHT AND HIGH CHANCE POPS WEDNESDAY THROUGH THURSDAY
AS THE SYSTEM WORKS ITS WAY THROUGH THE REGION. TEMPS COULD BE COLD
ENOUGH AT NIGHT TO SUPPORT SNOW OR A RAIN/SNOW MIX ACROSS NORTHERN
ZONES WHILE PRECIP WILL GENERALLY BE RAIN ACROSS SOUTHERN ZONES.
DURING THE DAY...PRECIP SHOULD BE ALL RAIN...THOUGH THIS COULD
CHANGE AS MODELS GET A BETTER HANDLE ON THE EVOLUTION OF THE SYSTEM.
HIGHS WEDNESDAY AND THURSDAY WILL TOP OFF IN THE MID TO UPPER 40S
AND LOWS AT NIGHT WILL DROP INTO THE LOW TO MID 30S.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
FR AS A WARM FRONT APPROACHES FROM THE S THIS MORNING. LOW PRESSURE
DEVELOPS ALONG THE FRONT THIS AFTERNOON. A COLD FRONT WILL THEN
SWEEP ACROSS THE AREA LATE THIS EVENING.
PRECIP OVER THE AREA AS OF 09Z WITH KSWF/KHPN/KBDR/KGON EXPERIENCING
SN OR MIXED. HEAVIEST PRECIP LIFTS NE BY 11Z...BECOMING MORE SHOWERY
WITH A CHANGEOVER TO RAIN AFTER SUNRISE.
IFR TO LOW IFR EXPECTED FOR MOST OF THE DAY WITH OCNL -SHRA. THERE
MAY BE A RELATIVE LULL IN PRECIP WITH DZ PREDOMINATING AFTER MID
MORNING. SHOWERS RETURN AHEAD OF THE COLD FRONT LATER IN THE EVENING
ON.
VFR RETURNS OVERNIGHT BEHIND THE FRONT WITH VERY STRONG GUSTY
WESTERLY WINDS.
NY METRO ENHANCED AVIATION WEATHER SUPPORT...
DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN
BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE)
KEWR FCSTER COMMENTS: CEILINGS MAY TAKE LONGER TO LOWER THIS MORNING
THAN CURRENTLY FORECAST. LOW CONFIDENCE IN WIND DIRECTION LATER THIS
AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
KJFK FCSTER COMMENTS: CEILINGS MAY TAKE LONGER TO LOWER THIS MORNING
THAN CURRENTLY FORECAST. LOW CONFIDENCE IN WIND DIRECTION LATER THIS
AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
KLGA FCSTER COMMENTS: CEILINGS MAY TAKE LONGER TO LOWER THIS MORNING
THAN CURRENTLY FORECAST. LOW CONFIDENCE IN WIND DIRECTION LATER THIS
AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
KTEB FCSTER COMMENTS: LOW CONFIDENCE IN WIND DIRECTION LATER THIS
AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
KHPN FCSTER COMMENTS: LOW CONFIDENCE IN WIND DIRECTION LATER THIS
AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
KISP FCSTER COMMENTS: LOW CONFIDENCE IN WIND DIRECTION LATER THIS
AFTERNOON GIVEN LOW PRESSURE TRACK UNCERTAINTY.
OUTLOOK FOR 06Z SAT THROUGH TUE...
.FRI NIGHT-SAT...VFR. STRONG/GUSTY W-NW FLOW. 40-45 KT POSSIBLE
EARLY...THEN GRADUALLY DIMINISHING.
.SUN-TUE...VFR.
&&
.MARINE...
MAIN CHANGES THIS UPDATE WAS TO REFLECT LATEST TRENDS IN
PRECIPITATION THIS MORNING. REMAINDER OF FORECAST APPEARS ON
TRACK.
WITH SCA ALREADY UP ON ALL WATERS...DID NOT WANT TO TAKE
DOWN...THOUGH GUSTS ON EASTERLY FLOW OF 10-20 KT MIGHT ONLY
OCCASIONALLY REACH SMALL CRAFT LEVELS TODAY...OVER THE OCEAN ZONES
THOUGH...SCA WARRANTED WITH SEAS ALREADY AT SCA LEVELS.
HAVE HOISTED A STORM WATCH FOR ALL WATERS TONIGHT AND SATURDAY.
THE BEST CHANCE FOR GUSTS TO STORM FORCE ON STRONG WEST WINDS IS
ACROSS SOUTHERN WATERS...THOUGH IF CURRENT FORECAST WIND DIRECTION
HOLDS...THEN CHANNELING EFFECTS IN THE SOUND COULD PROVIDE THE
EXTRA BOOST THERE.
THE TIMING FOR THE STRONGEST WIND GUSTS WILL BE LATE TONIGHT WHEN
THE STRONGEST WINDS PASS AT 900 HPA (AROUND 60 KT)...AND AGAIN
FROM LATE SATURDAY MORNING INTO SATURDAY AFTERNOON...WITH THE
POTENTIAL TO MIX DOWN 50-55 KT WINDS AROUND 800 HPA. THESE WINDS
SHOULD BUILD SEAS ON THE OCEAN TO 6 TO 13 FT AND ON THE SOUND TO
4-8 FT BY SATURDAY MORNING.
GALE FORCE WINDS WILL DIMINISH TO SMALL CRAFT ADVISORY LEVELS ON THE
WATERS FROM WEST TO EAST SATURDAY NIGHT...THEN CONDITIONS GRADUALLY
SUBSIDE TO SUB-ADVISORY LEVELS THROUGH SUNDAY AFTERNOON.
HIGH PRES BUILDS THROUGH THE WATERS FOR THE START OF THE NEW WEEK.
WINDS/SEAS SHOULD REMAIN BELOW SCA LEVELS...THOUGH SEAS MAY BRIEFLY
BUILD TO 3-5 FT ON THE EASTERN OCEAN WATERS MONDAY EVENING AS WEAK
LOW PRES PASSES EAST OF THE WATERS.
&&
.HYDROLOGY...
A STORM TOTAL LIQUID EQUIVALENT RAINFALL OF 1/2 TO 3/4 INCH IS
FORECAST THROUGH THIS EVENING. OTHERWISE...NO SIGNIFICANT PRECIP
IS EXPECTED UNTIL THE MIDDLE OF NEXT WEEK.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...WIND ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST SATURDAY FOR
CTZ005>012.
WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
CTZ005>012.
NY...HIGH WIND WATCH FROM THIS EVENING THROUGH SATURDAY AFTERNOON
FOR NYZ072>075-078>081-176>179.
WIND ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST SATURDAY FOR
NYZ067>071.
NJ... WIND ADVISORY FROM 10 PM THIS EVENING TO 6 PM EST SATURDAY FOR
NJZ002-004-006-103>108.
MARINE...STORM WATCH FROM THIS EVENING THROUGH SATURDAY AFTERNOON FOR
ANZ330-335-338-340-345-350-353-355.
SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ330-
335-338-340-345-350-353-355.
&&
$$
SYNOPSIS...MALOIT/MPS
NEAR TERM...MALOIT
SHORT TERM...MALOIT
LONG TERM...MPS
AVIATION...MAS
MARINE...MALOIT/MPS
HYDROLOGY...MALOIT/MPS
AREA FORECAST DISCUSSION
NWS ALBANY NY
538 AM EST FRI FEB 24 2012
.SYNOPSIS...
A COMPLEX LOW PRESSURE SYSTEM WILL AFFECT THE REGION THROUGH TONIGHT
WITH SNOW AND RAIN. SOME LINGERING SNOW SHOWERS ALONG WITH WINDY
CONDITIONS WILL OCCUR IN THE WAKE OF THE STORM ON SATURDAY. FAIR AND
CHILLY CONDITIONS WILL RETURN FOR SUNDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 500 AM...RADAR SHOWS THAT THE RUC SHORT TERM MODEL APPEARS TO
BE CORRECT THAT THE HEAVY BAND OF SNOW OVER THE SOUTHERN PART OF THE
FORECAST AREA WILL EXIT THE REGION TO THE EAST EARLY THIS MORNING...
AND ONLY RELATIVELY LIGHT SNOW WILL LIFT NORTH ACROSS THE REST OF
THE REGION. THIS WILL RESULT IN A LULL IN THE PCPN FOR MUCH OF THE
MORNING AND INTO EARLY THIS AFTERNOON...BEFORE ANOTHER ROUND OF
SIGNIFICANT PCPN MOVES IN LATER THIS AFTERNOON AHEAD OF THE FRONTAL
BOUNDARY ASSOCIATED WITH THE LOW MOVING THROUGH THE EASTERN GREAT
LAKES.
AS A RESULT...WITH NO WIDESPREAD SIGNIFICANT SNOW EXPECTED TO MAKE
IT NORTH OF GREENE...COLUMBIA AND BERKSHIRE COUNTY EARLY THIS
MORNING...DECIDED TO DROP THE WINTER WEATHER ADVISORY FOR THE
SCHOHARIE AND MOHAWK VALLEYS...THE HELDERBERGS AND THE NORTHERN
TACONICS. FURTHER NORTH SNOW WILL BE LIGHT THIS MORNING...BUT IT MAY
STILL BE COLD ENOUGH FOR ACCUMULATING SNOW THIS AFTERNOON WHEN THE
NEXT ROUND OF PCPN ARRIVES...SO THE WINTER WEATHER ADVISORY
CONTINUES ACROSS NORTHERN AREAS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
COMING SOON.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
DETERMINISTIC...BOTH 00Z EURO AND 00Z GFS SHOW WEAK UPPER IMPULSE
MOVING NORTH OF THE AREA ON MONDAY. SOME TIMING DIFFERENCES BUT
OVERALL IMPACT WILL BE FOR CLOUDS/CHANCE POPS OVER NORTHERN THIRD OF
AREA. REST OF AREA SHOULD REMAIN PARTLY SUNNY AND DRY. AFTER
IMPULSE PASSES BY A WEAK COLD FRONT CROSSES AREA MONDAY NIGHT. COLD
ADVECTION MAY LEAD TO SOME SCATTERED LAKE EFFECT SNOW SHOWERS SO
SLT/CHC POPS NORTHWEST EARLY TUESDAY BUT RIDGING SHOULD LEAD TO
MAINLY FAIR WEATHER ACROSS AREA. BY WEDNESDAY ANOTHER STORM SYSTEM
MOVES INTO GREAT LAKES REGION AND UP SAINT LAWRENCE AND LIKE PRESENT
STORM...THIS ONE BRINGS WINTRY MIX CHANGING TO RAIN AND BACK TO SNOW
DOWNWIND OF LAKE ONTARIO AND OVER HIGHER TERRAIN. EURO A LITTLE
SLOWER BUT BY LATE THURSDAY ALL BUT FAR NORTHWEST SHOULD BE DRY WITH
LINGERING LAKE EFFECT AND UPSLOPE SNOW SHOWERS. BOTH MODELS SHOW
RIDGING BUILDING INTO THE AREA ON FRIDAY WITH FAIR WEATHER.
PROBABILISTIC...00Z GEFS ENSEMBLES SHOW HIGHEST PROBABILITY OF
PRECIP ON WEDNESDAY INTO THURSDAY. EXTENDED STATISTICAL GUIDANCE
SHOWS TEMPS AVERAGING ABOVE NORMAL ALTHOUGH SATURDAY THROUGH MONDAY
WILL BE NEAR NORMAL.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
A LOW PRESSURE SYSTEM WILL APPROACH FROM THE OHIO VALLEY TONIGHT
BRINGING A WINTRY MIX WITH VFR CONDITIONS GIVING WAY TO MVFR/IFR
CONDITIONS BETWEEN 08Z AND 13Z FROM SOUTH TO NORTH. THE WINTRY MIX
IS THEN EXPECTED TO GRADUALLY CHANGE TO ALL RAIN AT THE TAF SITES
BTWN 13Z AND 18Z WITH KGFL BEING THE SLOWEST TO CHANGE TO RAIN.
MVFR/IFR CONDITIONS ARE EXPECTED AT THE TAF SITES FROM 16Z-18Z
THROUGH MOST OF THE REST OF THE TAF PERIOD EXCEPT AT KPOU WHICH
COULD BECOME VFR FOR THE LAST FEW HOURS.
WINDS WILL BE LIGHT AND VARIABLE THROUGH THE REST OF THE OVERNIGHT
AND THEN BECOME EAST NORTHEAST AT 6 KTS OR LESS FRIDAY MORNING AND
EAST TO SOUTHEAST AROUND 10 KTS OR LESS FRIDAY AFTERNOON. DEPENDING
ON THE TIMING OF A COLD FRONT PASSAGE WINDS MAY SWITCH TO SOUTHWEST
TO WEST NEAR THE END OF THE TAF PERIOD AND BECOME GUSTY.
OUTLOOK....
FRI...MVFR/IFR CIGS/VSBYS...TRANSITION TO RA FROM KPOU TO KGFL IN
THE MORNING.
FRI NGT...VFR/MVFR...CHC -SHSN. BECOMING WINDY.
SAT...VFR...SLIGHT CHC -SHSN. WINDY.
SAT NIGHT-SUN...VFR...DECREASING WINDS.
MON...VFR SLIGHT CHC -SHRA/-SHSN.
TUE...VFR.
&&
.HYDROLOGY...
SOME MODERATE RIVER RISES ARE POSSIBLE OVER THE SOUTHERN THIRD OF
OUR AREA TONIGHT AS RUNOFF FROM MELTING SNOW COMBINES WITH RUNOFF
FROM SOME HEAVIER DOWNPOURS AHEAD OF A COLD FRONT. SOME PONDING OF
WATER IN LOW LYING AND POOR DRAINAGE AREAS MAY SLOW THE EVENING
COMMUTE. NO LARGER RIVER FLOODING IS EXPECTED DURING THE NEXT 5 DAYS.
SOME GAGES ARE STILL BEING IMPACTED BY ICE ACROSS NORTHERN PORTIONS
OF THE HYDROLOGIC SERVICE AREA. PERSISTENT COLD TEMPERATURES THIS
WEEKEND MAY ALLOW ADDITIONAL ICE FORMATION TO OCCUR LATE SATURDAY
INTO EARLY MONDAY IN BASINS NORTH OF THE MOHAWK RIVER VALLEY.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...WIND ADVISORY FROM 1 AM TO 7 PM EST SATURDAY FOR CTZ001-013.
NY...WINTER WEATHER ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR
NYZ058-063.
WIND ADVISORY FROM 1 AM TO 7 PM EST SATURDAY FOR NYZ032-033-
038>043-047>054-058>061-063>066-082>084.
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NYZ032-
033-042-043-061-082-083.
MA...WIND ADVISORY FROM 1 AM TO 7 PM EST SATURDAY FOR MAZ001-025.
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR MAZ001-
025.
VT...WIND ADVISORY FROM 1 AM TO 7 PM EST SATURDAY FOR VTZ013>015.
WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR
VTZ013>015.
&&
$$
SYNOPSIS...GJM
NEAR TERM...GJM
SHORT TERM...GJM
LONG TERM...SND
AVIATION...SND
HYDROLOGY...SND
AREA FORECAST DISCUSSION
NWS ALBANY NY
535 AM EST FRI FEB 24 2012
.SYNOPSIS...
A COMPLEX LOW PRESSURE SYSTEM WILL AFFECT THE REGION THROUGH TONIGHT
WITH SNOW AND RAIN. SOME LINGERING SNOW SHOWERS ALONG WITH WINDY
CONDITIONS WILL OCCUR IN THE WAKE OF THE STORM ON SATURDAY. FAIR AND
CHILLY CONDITIONS WILL RETURN FOR SUNDAY.
&&
.NEAR TERM /UNTIL 6 PM TODAY/...
AS OF 500 AM...RADAR SHOWS THAT THE RUC SHORT TERM MODEL APPEARS TO
BE CORRECT THAT THE HEAVY BAND OF SNOW OVER THE SOUTHERN PART OF THE
FORECAST AREA WILL EXIT THE REGION TO THE EAST EARLY THIS MORNING...
AND ONLY RELATIVELY LIGHT SNOW WILL LIFT NORTH ACROSS THE REST OF
THE REGION. THIS WILL RESULT IN A LULL IN THE PCPN FOR MUCH OF THE
MORNING AND INTO EARLY THIS AFTERNOON...BEFORE ANOTHER ROUND OF
SIGNIFICANT PCPN MOVES IN LATER THIS AFTERNOON AHEAD OF THE FRONTAL
BOUNDARY ASSOCIATED WITH THE LOW MOVING THROUGH THE EASTERN GREAT
LAKES.
AS A RESULT...WITH NO WIDESPREAD SIGNIFICANT SNOW EXPECTED TO MAKE
IT NORTH OF GREENE...COLUMBIA AND BERKSHIRE COUNTY EARLY THIS
MORNING...DECIDED TO DROP THE WINTER WEATHER ADVISORY FOR THE
SCHOHARIE AND MOHAWK VALLEYS...THE HELDERBERGS AND THE NORTHERN
TACONICS. FURTHER NORTH SNOW WILL BE LIGHT THIS MORNING...BUT IT MAY
STILL BE COLD ENOUGH FOR ACCUMULATING SNOW THIS AFTERNOON WHEN THE
NEXT ROUND OF PCPN ARRIVES...SO THE WINTER WEATHER ADVISORY
CONTINUES ACROSS NORTHERN AREAS.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY/...
COMING SOON.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
DETERMINISTIC...BOTH 00Z EURO AND 00Z GFS SHOW WEAK UPPER IMPULSE
MOVING NORTH OF THE AREA ON MONDAY. SOME TIMING DIFFERENCES BUT
OVERALL IMPACT WILL BE FOR CLOUDS/CHANCE POPS OVER NORTHERN THIRD OF
AREA. REST OF AREA SHOULD REMAIN PARTLY SUNNY AND DRY. AFTER
IMPULSE PASSES BY A WEAK COLD FRONT CROSSES AREA MONDAY NIGHT. COLD
ADVECTION MAY LEAD TO SOME SCATTERED LAKE EFFECT SNOW SHOWERS SO
SLT/CHC POPS NORTHWEST EARLY TUESDAY BUT RIDGING SHOULD LEAD TO
MAINLY FAIR WEATHER ACROSS AREA. BY WEDNESDAY ANOTHER STORM SYSTEM
MOVES INTO GREAT LAKES REGION AND UP SAINT LAWRENCE AND LIKE PRESENT
STORM...THIS ONE BRINGS WINTRY MIX CHANGING TO RAIN AND BACK TO SNOW
DOWNWIND OF LAKE ONTARIO AND OVER HIGHER TERRAIN. EURO A LITTLE
SLOWER BUT BY LATE THURSDAY ALL BUT FAR NORTHWEST SHOULD BE DRY WITH
LINGERING LAKE EFFECT AND UPSLOPE SNOW SHOWERS. BOTH MODELS SHOW
RIDGING BUILDING INTO THE AREA ON FRIDAY WITH FAIR WEATHER.
PROBABILISTIC...00Z GEFS ENSEMBLES SHOW HIGHEST PROBABILITY OF
PRECIP ON WEDNESDAY INTO THURSDAY. EXTENDED STATISTICAL GUIDANCE
SHOWS TEMPS AVERAGING ABOVE NORMAL ALTHOUGH SATURDAY THROUGH MONDAY
WILL BE NEAR NORMAL.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
A LOW PRESSURE SYSTEM WILL APPROACH FROM THE OHIO VALLEY TONIGHT
BRINGING A WINTRY MIX WITH VFR CONDITIONS GIVING WAY TO MVFR/IFR
CONDITIONS BETWEEN 08Z AND 13Z FROM SOUTH TO NORTH. THE WINTRY MIX
IS THEN EXPECTED TO GRADUALLY CHANGE TO ALL RAIN AT THE TAF SITES
BTWN 13Z AND 18Z WITH KGFL BEING THE SLOWEST TO CHANGE TO RAIN.
MVFR/IFR CONDITIONS ARE EXPECTED AT THE TAF SITES FROM 16Z-18Z
THROUGH MOST OF THE REST OF THE TAF PERIOD EXCEPT AT KPOU WHICH
COULD BECOME VFR FOR THE LAST FEW HOURS.
WINDS WILL BE LIGHT AND VARIABLE THROUGH THE REST OF THE OVERNIGHT
AND THEN BECOME EAST NORTHEAST AT 6 KTS OR LESS FRIDAY MORNING AND
EAST TO SOUTHEAST AROUND 10 KTS OR LESS FRIDAY AFTERNOON. DEPENDING
ON THE TIMING OF A COLD FRONT PASSAGE WINDS MAY SWITCH TO SOUTHWEST
TO WEST NEAR THE END OF THE TAF PERIOD AND BECOME GUSTY.
OUTLOOK....
FRI...MVFR/IFR CIGS/VSBYS...TRANSITION TO RA FROM KPOU TO KGFL IN
THE MORNING.
FRI NGT...VFR/MVFR...CHC -SHSN. BECOMING WINDY.
SAT...VFR...SLIGHT CHC -SHSN. WINDY.
SAT NIGHT-SUN...VFR...DECREASING WINDS.
MON...VFR SLIGHT CHC -SHRA/-SHSN.
TUE...VFR.
&&
.HYDROLOGY...
SOME MODERATE RIVER RISES ARE POSSIBLE OVER THE SOUTHERN THIRD OF
OUR AREA TONIGHT AS RUNOFF FROM MELTING SNOW COMBINES WITH RUNOFF
FROM SOME HEAVIER DOWNPOURS AHEAD OF A COLD FRONT. SOME PONDING OF
WATER IN LOW LYING AND POOR DRAINAGE AREAS MAY SLOW THE EVENING
COMMUTE. NO LARGER RIVER FLOODING IS EXPECTED DURING THE NEXT 5 DAYS.
SOME GAGES ARE STILL BEING IMPACTED BY ICE ACROSS NORTHERN PORTIONS
OF THE HYDROLOGIC SERVICE AREA. PERSISTENT COLD TEMPERATURES THIS
WEEKEND MAY ALLOW ADDITIONAL ICE FORMATION TO OCCUR LATE SATURDAY
INTO EARLY MONDAY IN BASINS NORTH OF THE MOHAWK RIVER VALLEY.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...WINTER WEATHER ADVISORY UNTIL 2 PM EST FRIDAY FOR NYZ058-063.
WINTER WEATHER ADVISORY FROM 3 AM TO 6 PM EST FRIDAY FOR
NYZ032-033-042-043-061-082-083.
MA...WINTER WEATHER ADVISORY FROM 3 AM TO 6 PM EST FRIDAY FOR
MAZ001-025.
VT...WINTER WEATHER ADVISORY FROM 3 AM TO 6 PM EST FRIDAY FOR
VTZ013>015.
&&
$$
SYNOPSIS...GJM
NEAR TERM...GJM
SHORT TERM...GJM
LONG TERM...SND
AVIATION...SND
HYDROLOGY...SND
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
921 AM EST FRI FEB 24 2012
.SYNOPSIS...
A COLD FRONT WILL PUSH THROUGH THE REGION LATE THIS AFTERNOON AND
EVENING. NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED AHEAD OF
THE FRONT WITH SOME STORMS POSSIBLY BECOMING SEVERE. WINDY
CONDITIONS WILL EXIST THIS AFTERNOON AS WELL. COOLER HIGH
PRESSURE WILL BUILD INTO THE AREA TONIGHT AND REMAIN IN CONTROL
THIS WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
CONVECTION DEVELOPING ACROSS CENTRAL GEORGIA AT 14Z MOVING RAPIDLY
NORTHEAST INTO THE MIDLANDS/CSRA. TORNADO WATCH ISSUED FOR
MIDLANDS/CSRA UNTIL 400 PM. EXPECT SEVERE THUNDERSTORM THREAT TO
INCREASE DURING THE MORNING INTO THE EARLY AFTERNOON AHEAD OF
APPROACHING COLD FRONT WITH STRONG DEEP LAYER SHEAR AND MODERATE
INSTABILITY.
LATEST MESOANALYSIS INDICATES A CONTINUING NORTHWARD SURGE OF LOW
TO MID 60S DEWPOINTS WITHIN THE WARM SECTOR OVER THE SOUTHEASTERN
STATES. STRONG MOISTURE FLUX WAS ALSO NOTED ACCOMPANIED BY A 50-60
KNOT LOW LEVEL JET ON THE KCAE VAD WIND PROFILE. LIFTED INDEX
VALUES ARE ALREADY AROUND -2 TO -3 IN THE CSRA WITH SEVERAL
COMPOSITE INDICES ALREADY SUPPORTIVE OF STRONG TO SEVERE STORMS IF
THEY WERE PRESENT. 0-6KM SHEAR VALUES ARE IN EXCESS OF 60 KNOTS
AND WILL INCREASE FURTHER THROUGH THE AFTERNOON. REASONABLE
CONFIDENCE THAT SEVERE WEATHER WILL OCCUR SOMEWHERE ACROSS THE
CAROLINAS SUPPORTED BY SEVERAL HI-RES WRF MODELS INDICATING A
LINE OF CONVECTION...OR LINE SEGMENTS...DEVELOPING THIS MORNING
JUST AHEAD OF THE APPROACHING FRONTAL BOUNDARY AND STRENGTHENING
THE STORMS THROUGH THE AFTERNOON AS THEY MOVE INTO THE FORECAST
AREA LATE MORNING AND EARLY AFTERNOON.
SPC HAS OUTLOOKED THE FORECAST AREA IN A SLIGHT TO MODERATE RISK
OF SEVERE WEATHER WITH THE MAIN THREAT BEING DAMAGING WINDS WITH A
CHANCE OF TORNADOES AS WELL. THERE IS A POSSIBILITY THIS COULD BE
A SIGNIFICANT DAMAGING WIND EVENT AND WILL NEED TO BE MONITORED.
DESPITE THE SEVERE THUNDERSTORM RISK...WINDS WILL BE STRONG TODAY
DUE TO MIXING DOWN OF THE VERY STRONG LOW LEVEL WINDS AND
THEREFORE WILL BE ISSUING A LAKE WIND ADVISORY. THERE IS POTENTIAL
FOR A FEW WIND GUSTS TO APPROACH THE WIND ADVISORY CRITERIA OF 40
KNOTS BUT AM NOT CONFIDENT ENOUGH TO ISSUE THE WIND ADVISORY.
TEMPERATURES TODAY WILL BE TRICKY AS STRONG GRADIENT WINDS
OVERNIGHT HAVE KEPT THE BOUNDARY LAYER MIXED AND VERY WARM AND
CLOUDS WILL HAVE SOME IMPACT ON THE AMOUNT OF INSOLATION THAT CAN
TAKE PLACE. HAVE DECIDED TO BUMP UP MAX TEMPERATURES TODAY THOUGH
DUE TO THE WARM START AND ANY AMOUNT OF SUNSHINE WOULD BE ENOUGH
TO PUSH TEMPERATURES INTO THE MID AND UPPER 70S.
THE FRONT SHOULD PUSH THROUGH THE AREA BY 00Z WITH STORMS PUSHING
EAST OF THE FORECAST AREA BEING REPLACED BY CLEARING SKIES AND
BUILDING HIGH PRESSURE. WINDS WILL STAY UP THROUGH THE NIGHT AND
OVERNIGHT LOWS WILL RESULT FROM THE AMOUNT OF COLD ADVECTION THAT
CAN TAKE PLACE. FORECAST LOWS ARE EXPECTED TO FALL IN THE UPPER
30S TO LOWER 40S.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
HIGH PRESSURE WILL BUILD OVER THE AREA ON SATURDAY WITH A DRY
AIRMASS IN PLACE PROVIDING MOSTLY CLEAR SKIES. TEMPERATURES WILL
BE IN THE UPPER 50S TO AROUND 60 WITH A COOLER AIRMASS IN PLACE.
OVERNIGHT LOWS WILL BE IN THE UPPER 20S TO LOWER 30S SATURDAY
NIGHT. SUNDAY FEATURES SURFACE HIGH PRESSURE REMAINING OVER THE
FORECAST AREA WHILE AN UPPER DISTURBANCE WILL PASS BY TO THE
SOUTH. MODEL DATA SUGGESTS THAT THE BEST CHANCES FOR RAIN SUNDAY
AND SUNDAY NIGHT WILL REMAIN SOUTH OF THE FORECAST AREA BUT WILL
CONTINUE TO MENTION A SLIGHT CHANCE OF RAIN ACROSS THE SOUTHERN
HALF OF THE FORECAST AREA IN CASE THIS DISTURBANCE ENDS UP
SHIFTING A BIT FURTHER NORTH. A BLANKET OF HIGH CLOUDS WILL HAVE
AN IMPACT ON THE MAX TEMPERATURES SUNDAY ALONG WITH A PERSISTENT
NORTHERLY COMPONENT TO THE WIND...RESULTING IN HIGHS IN THE MID
50S. OVERNIGHT LOWS SUNDAY NIGHT SHOULD BE WARMER THAN SATURDAY
NIGHT WITH CLOUD COVER AND AIRMASS MODIFICATION.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
LITTLE CHANGE MADE DURING THIS PERIOD. MODELS ARE IN GOOD
AGREEMENT THROUGH THE LONG TERM WITH SOME MINOR DIFFERENCES IN
TIMING AND INTENSITY...HOWEVER OVERALL PATTERN IS VERY SIMILAR.
WEAK DISTURBANCE ALONG WEAK FRONTAL BOUNDARY OVER THE NORTHERN
GULF WILL BEGIN TO MOVE NORTHWARD SUNDAY NIGHT AND MONDAY AS LOW
PRESSURE OVER THE SOUTHERN PLAINS DEEPENS AND MOVES EASTWARD. THIS
WILL PUSH A WEAK WARM FRONT THROUGH THE REGION ON TUESDAY WITH A
COLD FRONT APPROACHING THE FORECAST AREA WEDNESDAY. HIGH PRESSURE
ALONG WITH DRIER AIR WILL MOVE INTO THE REGION FOR WEDNESDAY NIGHT
AND THURSDAY. TEMPERATURES THROUGH THE LONG TERM WILL BE NEAR
NORMAL MONDAY THEN ABOVE NORMAL TUESDAY THROUGH THURSDAY.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
MOISTURE TRANSPORT CONTINUES INTO THE REGION. 4-5 KFT WINDS
SOUTHWEST 40-50 KNOTS THIS MORNING INCREASE TO 60-65 KNOTS THIS
AFTERNOON. SPC HAS SLIGHT TO MODERATE RISK TODAY ENTIRE CWA. RUC MODEL BY
15Z GIVES LI=-6, CAPE=1800 J/KG, SWEAT>325, TT>50, PW 1.4-1.5
INCHES. AND SHOULD BECOME MORE UNSTABLE AHEAD OF COLD FRONT DURING
THE AFTERNOON WITH LOW LEVEL WARM AIR ADVECTION CONTINUING. THERE
IS THE POTENTIAL FOR A SIGNIFICANT SEVERE WEATHER EVENT DURING THE
EARLY AND MIDDLE PART OF THE AFTERNOON. BOWING ECHOES OR A LEWP OR
POSSIBLY A SQUALL LINE COULD MOVE THROUGH THE FORECAST AREA.
GENERALLY, MAINLY VFR CONDITIONS UNTIL EARLY THIS AFTERNOON...THEN
MVFR CIGS WITH POSSIBLE IFR CONDITIONS IN SHOWERS AND
THUNDERSTORMS. CONDITIONS MAY PERSIST ENTIRE AFTERNOON. LOW LEVEL
MIXING COULD BRING THE 60-65 KNOT WINDS TO THE SURFACE. AFTER
ABOUT 22Z...THE COLD FRONT SHOULD HAVE MOVED EAST TAKING THE
WEATHER WITH IT AND CONDITIONS ARE EXPECTED TO IMPROVE EXCEPT FOR
GUSTY SURFACE WINDS 15-25 KNOTS IN A STRONG PRESSURE GRADIENT WITH
THE SYSTEM. SKIES SHOULD CLEAR 02Z-04Z TIME FRAME THIS EVENING.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS ARE POSSIBLE
TUESDAY INTO WEDNESDAY AHEAD OF ANOTHER COLD FRONT.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...LAKE WIND ADVISORY UNTIL 6 PM EST SATURDAY FOR SCZ015-016-018-
020>022-025>031-035>038-041.
GA...LAKE WIND ADVISORY UNTIL 6 PM EST SATURDAY FOR GAZ040-063>065-
077.
&&
$$
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...07
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
627 AM EST FRI FEB 24 2012
.SYNOPSIS...
A COLD FRONT WILL PUSH THROUGH THE REGION LATE THIS AFTERNOON AND
EVENING. NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED AHEAD OF
THE FRONT WITH SOME STORMS POSSIBLY BECOMING SEVERE. WINDY
CONDITIONS WILL EXIST THIS AFTERNOON AS WELL. COOLER HIGH
PRESSURE WILL BUILD INTO THE AREA TONIGHT AND REMAIN IN CONTROL
THIS WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
MAIN CONCERN IN THE NEAR TERM IS POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS ACCOMPANYING AN APPROACHING FRONTAL BOUNDARY. LATEST
WATER VAPOR IMAGERY SHOWING AN AMPLIFYING TROUGH OVER THE PLAINS
STATES WITH ONGOING CONVECTION OCCURRING OVER THE EASTERN OHIO
VALLEY.
LATEST MESOANALYSIS INDICATES A CONTINUING NORTHWARD SURGE OF LOW
TO MID 60S DEWPOINTS WITHIN THE WARM SECTOR OVER THE SOUTHEASTERN
STATES. STRONG MOISTURE FLUX WAS ALSO NOTED ACCOMPANIED BY A 50-60
KNOT LOW LEVEL JET ON THE KCAE VAD WIND PROFILE. LIFTED INDEX
VALUES ARE ALREADY AROUND -2 TO -3 IN THE CSRA WITH SEVERAL
COMPOSITE INDICES ALREADY SUPPORTIVE OF STRONG TO SEVERE STORMS IF
THEY WERE PRESENT. 0-6KM SHEAR VALUES ARE IN EXCESS OF 60 KNOTS
AND WILL INCREASE FURTHER THROUGH THE AFTERNOON. REASONABLE
CONFIDENCE THAT SEVERE WEATHER WILL OCCUR SOMEWHERE ACROSS THE
CAROLINAS SUPPORTED BY SEVERAL HI-RES WRF MODELS INDICATING A
LINE OF CONVECTION...OR LINE SEGMENTS...DEVELOPING THIS MORNING
JUST AHEAD OF THE APPROACHING FRONTAL BOUNDARY AND STRENGTHENING
THE STORMS THROUGH THE AFTERNOON AS THEY MOVE INTO THE FORECAST
AREA LATE MORNING AND EARLY AFTERNOON.
SPC HAS OUTLOOKED THE FORECAST AREA IN A SLIGHT RISK OF SEVERE
WEATHER WITH THE MAIN THREAT BEING DAMAGING WINDS WITH A CHANCE OF
TORNADOES AS WELL. THERE IS A POSSIBILITY THIS COULD BE A
SIGNIFICANT DAMAGING WIND EVENT AND WILL NEED TO BE MONITORED.
DESPITE THE SEVERE THUNDERSTORM RISK...WINDS WILL BE STRONG TODAY
DUE TO MIXING DOWN OF THE VERY STRONG LOW LEVEL WINDS AND
THEREFORE WILL BE ISSUING A LAKE WIND ADVISORY. THERE IS POTENTIAL
FOR A FEW WIND GUSTS TO APPROACH THE WIND ADVISORY CRITERIA OF 40
KNOTS BUT AM NOT CONFIDENT ENOUGH TO ISSUE THE WIND ADVISORY.
TEMPERATURES TODAY WILL BE TRICKY AS STRONG GRADIENT WINDS
OVERNIGHT HAVE KEPT THE BOUNDARY LAYER MIXED AND VERY WARM AND
CLOUDS WILL HAVE SOME IMPACT ON THE AMOUNT OF INSOLATION THAT CAN
TAKE PLACE. HAVE DECIDED TO BUMP UP MAX TEMPERATURES TODAY THOUGH
DUE TO THE WARM START AND ANY AMOUNT OF SUNSHINE WOULD BE ENOUGH
TO PUSH TEMPERATURES INTO THE MID AND UPPER 70S.
THE FRONT SHOULD PUSH THROUGH THE AREA BY 00Z WITH STORMS PUSHING
EAST OF THE FORECAST AREA BEING REPLACED BY CLEARING SKIES AND
BUILDING HIGH PRESSURE. WINDS WILL STAY UP THROUGH THE NIGHT AND
OVERNIGHT LOWS WILL RESULT FROM THE AMOUNT OF COLD ADVECTION THAT
CAN TAKE PLACE. FORECAST LOWS ARE EXPECTED TO FALL IN THE UPPER
30S TO LOWER 40S.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
HIGH PRESSURE WILL BUILD OVER THE AREA ON SATURDAY WITH A DRY
AIRMASS IN PLACE PROVIDING MOSTLY CLEAR SKIES. TEMPERATURES WILL
BE IN THE UPPER 50S TO AROUND 60 WITH A COOLER AIRMASS IN PLACE.
OVERNIGHT LOWS WILL BE IN THE UPPER 20S TO LOWER 30S SATURDAY
NIGHT. SUNDAY FEATURES SURFACE HIGH PRESSURE REMAINING OVER THE
FORECAST AREA WHILE AN UPPER DISTURBANCE WILL PASS BY TO THE
SOUTH. MODEL DATA SUGGESTS THAT THE BEST CHANCES FOR RAIN SUNDAY
AND SUNDAY NIGHT WILL REMAIN SOUTH OF THE FORECAST AREA BUT WILL
CONTINUE TO MENTION A SLIGHT CHANCE OF RAIN ACROSS THE SOUTHERN
HALF OF THE FORECAST AREA IN CASE THIS DISTURBANCE ENDS UP
SHIFTING A BIT FURTHER NORTH. A BLANKET OF HIGH CLOUDS WILL HAVE
AN IMPACT ON THE MAX TEMPERATURES SUNDAY ALONG WITH A PERSISTENT
NORTHERLY COMPONENT TO THE WIND...RESULTING IN HIGHS IN THE MID
50S. OVERNIGHT LOWS SUNDAY NIGHT SHOULD BE WARMER THAN SATURDAY
NIGHT WITH CLOUD COVER AND AIRMASS MODIFICATION.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
LITTLE CHANGE MADE DURING THIS PERIOD. MODELS ARE IN GOOD
AGREEMENT THROUGH THE LONG TERM WITH SOME MINOR DIFFERENCES IN
TIMING AND INTENSITY...HOWEVER OVERALL PATTERN IS VERY SIMILAR.
WEAK DISTURBANCE ALONG WEAK FRONTAL BOUNDARY OVER THE NORTHERN
GULF WILL BEGIN TO MOVE NORTHWARD SUNDAY NIGHT AND MONDAY AS LOW
PRESSURE OVER THE SOUTHERN PLAINS DEEPENS AND MOVES EASTWARD. THIS
WILL PUSH A WEAK WARM FRONT THROUGH THE REGION ON TUESDAY WITH A
COLD FRONT APPROACHING THE FORECAST AREA WEDNESDAY. HIGH PRESSURE
ALONG WITH DRIER AIR WILL MOVE INTO THE REGION FOR WEDNESDAY NIGHT
AND THURSDAY. TEMPERATURES THROUGH THE LONG TERM WILL BE NEAR
NORMAL MONDAY THEN ABOVE NORMAL TUESDAY THROUGH THURSDAY.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
MOISTURE TRANSPORT CONTINUES INTO THE REGION. 4-5 KFT WINDS
SOUTHWEST 40-50 KNOTS THIS MORNING INCREASE TO 60-65 KNOTS THIS
AFTERNOON. SPC HAS SLIGHT RISK TODAY ENTIRE CWA. RUC MODEL BY 15Z
GIVES LI=-6, CAPE=1800 J/KG, SWEAT>325, TT>50, PW 1.4-1.5 INCHES.
AND SHOULD BECOME MORE UNSTABLE AHEAD OF COLD FRONT DURING THE
AFTERNOON WITH LOW LEVEL WARM AIR ADVECTION CONTINUING. THERE IS THE
POTENTIAL FOR A SIGNIFICANT SEVERE WEATHER EVENT DURING THE EARLY
AND MIDDLE PART OF THE AFTERNOON. BOWING ECHOES OR A LEWP OR
POSSIBLY A SQUALL LINE COULD MOVE THROUGH THE FORECAST AREA.
GENERALLY, MAINLY VFR CONDITIONS UNTIL EARLY THIS AFTERNOON...THEN
MVFR CIGS WITH POSSIBLE IFR CONDITIONS IN SHOWERS AND THUNDERSTORMS.
CONDITIONS MAY PERSIST ENTIRE AFTERNOON. LOW LEVEL MIXING COULD
BRING THE 60-65 KNOT WINDS TO THE SURFACE. AFTER ABOUT 22Z...THE
COLD FRONT SHOULD HAVE MOVED EAST TAKING THE WEATHER WITH IT AND
CONDITIONS ARE EXPECTED TO IMPROVE EXCEPT FOR GUSTY SURFACE WINDS
15-25 KNOTS IN A STRONG PRESSURE GRADIENT WITH THE SYSTEM. SKIES
SHOULD CLEAR 02Z-04Z TIME FRAME THIS EVENING.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CONDITIONS ARE POSSIBLE
TUESDAY INTO WEDNESDAY AHEAD OF ANOTHER COLD FRONT.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...LAKE WIND ADVISORY UNTIL 6 PM EST SATURDAY FOR SCZ015-016-018-
020>022-025>031-035>038-041.
GA...LAKE WIND ADVISORY UNTIL 6 PM EST SATURDAY FOR GAZ040-063>065-
077.
&&
$$
SYNOPSIS...HC
NEAR TERM...HC
SHORT TERM...HC
LONG TERM...HC
AVIATION...TTH
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
804 AM CST FRI FEB 24 2012
.UPDATE...
THE DEFORMATION ZONE IS NOW EAST OF THE CWFA. ALL HEADLINES HAVE
BEEN DROPPED AS OF 8 AM.
...08..
&&
.PREV DISCUSSION... /ISSUED 545 AM CST FRI FEB 24 2012/
UPDATE...
RADAR TRENDS SHOW THE LAST OF THE DEFORMATION ZONE PRECIPITATION
OVER THE EASTERN CWFA. THIS IS SLIGHTLY FASTER THAN WHAT THE RUC
SUGGESTED A FEW HOURS AGO. BASED ON RADAR AND RUC TRENDS THE
HEADLINES FOR MOST OF THE AREA WILL EXPIRE AT 12Z. WHITESIDE...
HENRY...BUREAU...AND PUTNAM COUNTIES WILL CONTINUE THEIR
RESPECTIVE ADVISORIES WHERE THE RELATIVELY HEAVIER SNOW WILL
CONTINUE FOR A FEW MORE HOURS.
SNOW WILL CONTINUE TO FALL OVER MUCH OF THE AREA THROUGH MID
MORNING BUT WITH VISIBILITIES IMPROVING ANY NEW ACCUMULATION WILL
BE UNDER ONE HALF INCH. THE FCST FOR THE AFTERNOON STILL LOOKS
REASONABLE WITH STEEP LOW LEVEL LAPSE RATES WITH CYCLONIC FLOW AND
A VORT MAX ROTATING THROUGH THE AREA.
THE FCST WILL BE UPDATED HOURLY THROUGH 8 AM TO REFLECT THE
HEADLINES DROPPING OFF.
.08..
AVIATION...
IFR TO LIFR CONDITIONS WILL IMPROVE TO MVFR THROUGH 18Z/24. MVFR
CONDITIONS WILL CONTINUE THROUGH 00Z/25 WITH POSSIBLE SHSN. IF A
SHSN WOULD IMPACT A TAF SITE...IFR OR LIFR CONDITIONS MAY BE
BRIEFLY SEEN. AFT 00Z/25 CONDITIONS WILL SLOWLY IMPROVE TO VFR.
.08..
PREV DISCUSSION... /ISSUED 317 AM CST FRI FEB 24 2012/
SYNOPSIS...
06Z SFC ANALYSIS HAS A LOW NEAR KDNV WITH THE MAIN SYNOPTIC LOW
SOUTHEAST OF KCEZ BUT STILL WEST OF CINCINNATI. A SUGGESTED MESO LOW
WAS SOUTH OF KVYS BUT EAST OF KC75 ALONG THE ILLINOIS RIVER. AN
INVERTED TROF RAN NORTHWEST FROM THE MESO LOW INTO WESTERN WISCONSIN
WHILE A SECONDARY TROF RAN FROM THE LOW WEST INTO NORTHERN MISSOURI.
DEW POINTS WERE IN THE 20S AND 30S ACROSS MUCH OF THE MIDWEST WITH
40S AND HIGHER IN THE OHIO VALLEY AND DEEP SOUTH. RADAR TRENDS SHOW
THE DEFORMATION ZONE MOVING EAST ACROSS THE AREA.
SHORT TERM...TODAY AND TONIGHT...
THE IMMEDIATE CONCERN IS WHAT TO DO WITH CURRENT HEADLINES.
OVERALL...TRENDS FROM THE RUC ARE QUITE USEFUL IN DEPICTING THE
CURRENT WX. A COMBINATION OF THE HEAVY RAIN TOOL WITH OVERALL
FORCING/CONDENSATION PRESSURE DEFICITS INDICATES THAT SNOW WILL
STILL BE ONGOING ACROSS THE EASTERN CWFA AT 12Z IN THE DEFORMATION
ZONE. AS SUCH...THE CURRENT HEADLINES WILL BE EXTENDED FOR 1-2 HRS
FOR HENRY...WHITESIDE...BUREAU...AND PUTNAM COUNTIES IN ILLINOIS.
AFT 14Z...RUC TRENDS SHOW THE OVERALL FORCING FALLING APART WITH
CONDENSATION PRESSURE DEFICITS RISING A LITTLE. HOWEVER...THE
OVERALL ATMOSPHERE REMAINS SATURATED SO WHILE THE INTENSITY OF THE
SNOW WILL LET UP TO POSSIBLY ONLY FLURRIES...-SN SHOULD CONTINUE
DURING THE MORNING HOURS.
BY LATE MORNING AND CONTINUING INTO THE AFTERNOON LOW LEVEL LAPSE
RATES BECOME VERY STEEP. THE RUC ALONG WITH OTHER MODELS SHOW A
RESPECTABLE VORT MAX ROTATING THROUGH THE AREA WHICH SHOULD INDUCE
SHSN FROM LATE MORNING THROUGH THE AFTERNOON HOURS. THE STEEP LAPSE
RATES WILL ALSO ALLOW HIGHER MOMENTUM AIR TO MIX DOWN RESULTING IN
BRISK IF NOT WINDY CONDITIONS.
ADDITIONAL SNOW ACCUMULATIONS AFTER 12Z SHOULD BE GENERALLY ONE HALF
INCH OR LESS.
TONIGHT...LOW LEVEL LAPSE RATES REMAIN QUITE STEEP WITH NO
STABILIZATION OCCURRING UNTIL ROUGHLY SUNRISE. ADD INTO THIS
CHANNELED VORTICITY WITH SOME CYCLONIC FLOW ACROSS THE AREA AND
CLOUDS MAY BE SLOW TO BREAK UP OR CLEAR OUT. THEREFORE...WILL HOLD
ONTO THE CLOUDS LONGER. ADDITIONALLY...SINCE SUNSET IS NOW CLOSER TO
6 PM THERE MAY BE SOME LINGERING FLURRIES OR DECAYING SHSN INTO THE
EARLY EVENING ACROSS THE EASTERN CWFA.
08..
LONG TERM...
AN ACTIVE WEATHER REGIME WILL BE IN PLACE THROUGH THE LONG TERM
FORECAST. MODELS ARE IN AGREEMENT WITH A POTENT S/W PASSING TO OUR
NORTH LATE IN THE WEEKEND WITH A SIGNIFICANT TROF MOVING THROUGH
MID-WEEK.
FOR SATURDAY AND SATURDAY NIGHT...A HIGH PRESSURE RIDGE WILL BE OVER
THE AREA EARLY SATURDAY. THE RIDGE IS PUSHED EAST BY SATURDAY
EVENING AS S/W ENERGY MOVES OUT OF THE PAC NW INTO THE NORTHERN
PLAINS...DRIVING A SURFACE LOW INTO THE EASTERN DAKOTAS BY SUNDAY
MORNING. EXPECT DRY CONDITIONS DURING THE PERIOD SO TEMPERATURES
WILL BE THE MAIN CONCERN. LIMITED MIXING IN THE RIDGE AXIS
SATURDAY WILL LIMIT HIGHS. THERE MAY ALSO BE SOME RESIDUAL SNOW
COVER NORTH FROM THE CURRENT EVENT...SO WILL KEEP HIGHS IN THE
30S. MINS SATURDAY NIGHT WILL LIKELY OCCUR DURING THE EVENING AS
SOUTHERLY FLOW BEGINS INCREASING AHEAD OF THE NORTHERN PLAINS
SURFACE LOW. KEPT MINS AROUND 20 IN THE NORTHEAST WHERE BEST
COOLING POTENTIAL EXISTS WITH LIGHT WINDS IN THE EVENING AND
POSSIBLY SOME SNOW STILL ON THE GROUND. LOWS IN THE SOUTHWEST
SHOULD OCCUR FAIRLY EARLY IN THE EVENING...SO KEPT THAT AREA IN THE
LOW 30S. TEMPS SHOULD STEADY OUT OR RISE SOME DURING THE LATE
EVENING AND OVERNIGHT HOURS.
SUNDAY AND SUNDAY NIGHT THE NORTHERN PLAINS S/W AND SURFACE LOW
WILL CROSS MN AND MOVE INTO THE GREAT LAKES BY MONDAY MORNING. A
COLD FRONT BEHIND THE SYSTEM WILL DROP SOUTHEAST THROUGH THE
FORECAST AREA SUNDAY NIGHT. WITH LIMITED MOISTURE AND THE BEST
FORCING STAYING WELL NORTH OF THE CWFA...HAVE REMOVED THE LOW POPS
FROM THE NORTH. HIGHS IN THE 40S NORTH TO MID 50S FAR SOUTH LOOK
REASONABLE WITH THE FORECAST AREA IN THE WARM SECTOR SUNDAY...AND
GUSTY SOUTHWEST WINDS TO AID DEEP MIXING. THE COLD FRONT WILL MOVE
THROUGH SUNDAY NIGHT...BUT THE AIR BEHIND THE FRONT IS NOT THAT
COLD...SO KEPT MINS IN THE MID 20S TO LOW 30S.
THE NEXT SYSTEM TO IMPACT THE AREA IS A SIGNIFICANT TROF THAT IS
EXPECTED TO MOVE INTO THE CA COAST MONDAY AND HEAD EAST INTO THE
PLAINS BY TUESDAY EVENING. THE MODELS WERE COMING INTO DECENT
AGREEMENT ON THE 24/00Z RUN WITH THIS SYSTEM TAKING A MORE
NORTHERN TRACK...LIFTING THE SURFACE LOW THROUGH NW IA TUESDAY
NIGHT AND INTO THE GREAT LAKES BY LATE WEDNESDAY. WITH GOOD
AGREEMENT AMONG THE LONG RANGE MODELS THE BLENDED GUIDANCE HAS
WARMED TEMPERATURES UP CONSIDERABLY MONDAY NIGHT THROUGH
WEDNESDAY. HAVE EVEN BUMPED UP TEMPERATURES A FEW DEGREES FROM
GUIDANCE MONDAY NIGHT AND TUESDAY WHEN IT APPEARS WE WILL BE IN
THE WARM SECTOR. THE SYSTEM SHOULD HAVE SOME GULF MOISTURE TO WORK
WITH AS IT MOVES THROUGH THE MID MS VALLEY SO MAINTAINED HIGH
CHANCE OR LIKELY POPS TUESDAY INTO WEDNESDAY. SOME THUNDERSTORMS
CANNOT BE RULED OUT FOR TUESDAY NIGHT WHEN THE BEST FORCING WILL
LIFT THROUGH THE AREA. HOWEVER...I DID NOT MENTION ANY THUNDER
YET...SINCE THERE IS STILL POTENTIAL FOR THE MODEL SOLUTIONS TO
VARY. STRONG WEST TO NORTHWEST WINDS WILL USHER IN COLDER AIR LATE
TUESDAY NIGHT AND WEDNESDAY AS THE OCCLUDED SYSTEM LIFTS NORTHEAST
THROUGH WI AND INTO THE GREAT LAKES. WITH THE COLD AIR MOVING BACK
IN ANY LINGERING PRECIP WILL MIX WITH OR CHANGE TO SNOW. BY
THURSDAY TEMPERATURES SHOULD BE BACK TO NEAR NORMAL. ..DLF..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
546 AM CST FRI FEB 24 2012
...UPDATED AVIATION DISCUSSION...
.SHORT TERM /TODAY/...
ACCUMULATING SNOW QUICKLY DIMINISHING AS SURFACE LOW CONTINUES TO
PULL EAST THIS MORNING. MAIN CONCERN TODAY IS WITH WINDS AND
POTENTIAL FOR SNOW SHOWERS. CAA WILL CONTINUE TO INCREASE THROUGHOUT
THE DAY WITH PRESSURE GRADIENT AND SOME MIXING. MIXING WILL BE
SOMEWHAT LIMITED TO THE STRATUS DECK HOLDING STRONG THROUGH THE DAY.
WINDS ATOP THE MIXED LAYER NEARING 40KTS BY LATE THIS
AFTERNOON...BUT THINKING THE RUC IS A LITTLE OVERDONE AND LEANED
TOWARD THE SREF/NAM FOR WINDS. THE 925-850MB RH PERSISTS TODAY AND
IS WELL WITHIN THE SNOW GROWTH ZONE...ESPECIALLY OVER THE EASTERN
AND NORTHERN SECTIONS OF THE FORECAST AREA. KEPT WITH MENTION OF
SNOW SHOWERS TODAY AND LIGHT ACCUMULATIONS...MAY SEE A HALF INCH
FROM THE ALO TO MCW AREA. NOT ANTICIPATING TEMPS TO RISE ALL THAT
MUCH TODAY WITH THE CAA...STRATUS DECK...AND FRESH SNOW PACK. SO
WENT SLIGHTLY BELOW GUIDANCE FOR MAX TEMPS TODAY.
.LONG TERM /TONIGHT THROUGH THURSDAY/...
TWO SIGNIFICANT SYSTEMS TO CONTEND WITH THROUGH THIS
PERIOD...PRECEDED BY VERY MINOR WAVE TONIGHT. THE LATTER IS
EXPECTED TO CROSS THE NRN ROCKIES INTO THE LOWER MO RIVER VALLEY BY
THIS AFTERNOON AND THIS EVENING. WAVE IS CURRENTLY GENERATING SOME
LIGHT SNOW OR FLURRIES ACROSS MT/ND SO HAVE ADDED TRACE WORDING SW
DURING THE EVENING TO ACCOUNT FOR THIS. MODEL REFLECTION OF THIS
SYSTEM QUITE VARIABLE WITH GEM REGIONAL AND GLOBAL MOST
AGGRESSIVE...WHILE THE ECMWF AND DOMESTIC MODELS ARE WEAKER. ANY
FORCING IS VERY COMPACT HOWEVER SO DAY SHIFT WILL HAVE TO EXAMINE
WHETHER STRENGTH IS SUFFICIENT TO WARRANT MEASURABLE MENTION AND IF
SO WHETHER IT CLIPS US OR STAYS JUST TO THE SOUTH AND WEST.
NEXT SYSTEM CURRENTLY OFF THE PACIFIC NW COAST WILL CROSS THE
ROCKIES SAT BEFORE AMPLIFYING AS IT ENTERS THE MID MO VALLEY.
FORCING...BOTH KINEMATIC AND THERMODYNAMIC...IS QUITE IMPRESSIVE
WITH THIS SYSTEM SAT NIGHT BUT MOISTURE BELOW 2.5KM IS SPARSE. BY
SUN AIRMASS REMAINS DRY WITH DOWNWARD MOTION QUICKLY SURGING IN
BEHIND SHARP QG FORCING COUPLET SO HAVE REMOVED NRN POPS ON SUN.
CONSIDERING THE STRENGTH OF THE LIFT SAT NIGHT THAT MAY BE A BETTER
POTENTIAL PRECIP WINDOW AND MAY NEED TO ADD TRACE AMOUNTS AT SOME
POINT IF MOISTURE CAN INCREASE SLIGHTLY.
NEXT SYSTEM WHICH IS EVEN STRONGER WITH SIMILAR BUT SLIGHTLY MORE
SOUTHERLY PATH WILL ENTER MO VALLEY LATE TUE. 00Z GFS/ECMWF ARE NOW
IN QUITE GOOD AGREEMENT TRACKING DEEP SURFACE LOW ACROSS NWRN IA TUE
EVENING. ALTHOUGH POTENT SNOW STORM MAY AFFECT DAKOTAS AND
MN...THIS PATH WILL KEEP IA MAINLY IN THE WARM SECTOR WHICH HAS
RESULTED IN WARMER TEMP FORECAST MON INTO TUE...ALONG WITH FURTHER
NUDGING UPWARD OF POPS. OVERALL FORCING WILL GRADUALLY INCREASE MON
NIGHT WITH SNOW POSSIBLE THEN INCREASE FURTHER TUE AND TUE NIGHT
WITH TRANSITION TO RAIN SHOWERS. HAVE ALSO ADDED ISOLATED THUNDER
CONSIDERING OVERALL STRENGTH OF LIFT ALONG WITH SHOWALTERS HOVERING
AROUND ZERO AND K INDICES WELL INTO THE 20S AND LOWER 30S. AS
SYSTEM PULLS AWAY WINDS WILL BECOME THE PRIMARY FEATURE FOR IA.
MODEL CONSENSUS SUGGESTS SUSTAINED SPEEDS ABOVE 20KTS SOUTH AND WEST
BY MIDDAY WED WITH GUSTS AT HIGH AS 35-40KTS.
&&
.AVIATION...24/12Z
MVFR STRATUS DECK WILL PERSIST THROUGHOUT THE DAY TODAY AND KEPT
CIGS B/T 2500-3000 FEET THROUGH THIS EVENING. WINDS LOOK TO GUST TO
AROUND 25 TO 30KNOTS LATE THIS MORNING INTO THE AFTERNOON AND LIKELY
WILL SEE SOME SNOW SHOWERS. LOW CONFIDENCE WITH ANY VISIBILITY
RESTRICTIONS WITHIN THE SNOW SHOWERS TODAY...BUT COULD SEE A FEW
SHORT BURST OF MVFR VIS THIS AFTERNOON. STRONG GUSTS WILL DIMINISH
BY 00Z...BUT STILL SHOULD HAVE SOME STRONG SUSTAINED WINDS INTO
SATURDAY MORNING.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...KLP
LONG TERM...BSS
AVIATION...KLP
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
545 AM CST FRI FEB 24 2012
.UPDATE...
RADAR TRENDS SHOW THE LAST OF THE DEFORMATION ZONE PRECIPITATION
OVER THE EASTERN CWFA. THIS IS SLIGHTLY FASTER THAN WHAT THE RUC
SUGGESTED A FEW HOURS AGO. BASED ON RADAR AND RUC TRENDS THE
HEADLINES FOR MOST OF THE AREA WILL EXPIRE AT 12Z. WHITESIDE...
HENRY...BUREAU...AND PUTNAM COUNTIES WILL CONTINUE THEIR
RESPECTIVE ADVISORIES WHERE THE RELATIVELY HEAVIER SNOW WILL
CONTINUE FOR A FEW MORE HOURS.
SNOW WILL CONTINUE TO FALL OVER MUCH OF THE AREA THROUGH MID
MORNING BUT WITH VISIBILITIES IMPROVING ANY NEW ACCUMULATION WILL
BE UNDER ONE HALF INCH. THE FCST FOR THE AFTERNOON STILL LOOKS
REASONABLE WITH STEEP LOW LEVEL LAPSE RATES WITH CYCLONIC FLOW AND
A VORT MAX ROTATING THROUGH THE AREA.
THE FCST WILL BE UPDATED HOURLY THROUGH 8 AM TO REFLECT THE
HEADLINES DROPPING OFF.
..08..
&&
.AVIATION...
IFR TO LIFR CONDITIONS WILL IMPROVE TO MVFR THROUGH 18Z/24. MVFR
CONDITIONS WILL CONTINUE THROUGH 00Z/25 WITH POSSIBLE SHSN. IF A
SHSN WOULD IMPACT A TAF SITE...IFR OR LIFR CONDITIONS MAY BE
BRIEFLY SEEN. AFT 00Z/25 CONDITIONS WILL SLOWLY IMPROVE TO VFR.
..08..
&&
.PREV DISCUSSION... /ISSUED 317 AM CST FRI FEB 24 2012/
SYNOPSIS...
06Z SFC ANALYSIS HAS A LOW NEAR KDNV WITH THE MAIN SYNOPTIC LOW
SOUTHEAST OF KCEZ BUT STILL WEST OF CINCINNATI. A SUGGESTED MESO LOW
WAS SOUTH OF KVYS BUT EAST OF KC75 ALONG THE ILLINOIS RIVER. AN
INVERTED TROF RAN NORTHWEST FROM THE MESO LOW INTO WESTERN WISCONSIN
WHILE A SECONDARY TROF RAN FROM THE LOW WEST INTO NORTHERN MISSOURI.
DEW POINTS WERE IN THE 20S AND 30S ACROSS MUCH OF THE MIDWEST WITH
40S AND HIGHER IN THE OHIO VALLEY AND DEEP SOUTH. RADAR TRENDS SHOW
THE DEFORMATION ZONE MOVING EAST ACROSS THE AREA.
SHORT TERM...TODAY AND TONIGHT...
THE IMMEDIATE CONCERN IS WHAT TO DO WITH CURRENT HEADLINES.
OVERALL...TRENDS FROM THE RUC ARE QUITE USEFUL IN DEPICTING THE
CURRENT WX. A COMBINATION OF THE HEAVY RAIN TOOL WITH OVERALL
FORCING/CONDENSATION PRESSURE DEFICITS INDICATES THAT SNOW WILL
STILL BE ONGOING ACROSS THE EASTERN CWFA AT 12Z IN THE DEFORMATION
ZONE. AS SUCH...THE CURRENT HEADLINES WILL BE EXTENDED FOR 1-2 HRS
FOR HENRY...WHITESIDE...BUREAU...AND PUTNAM COUNTIES IN ILLINOIS.
AFT 14Z...RUC TRENDS SHOW THE OVERALL FORCING FALLING APART WITH
CONDENSATION PRESSURE DEFICITS RISING A LITTLE. HOWEVER...THE
OVERALL ATMOSPHERE REMAINS SATURATED SO WHILE THE INTENSITY OF THE
SNOW WILL LET UP TO POSSIBLY ONLY FLURRIES...-SN SHOULD CONTINUE
DURING THE MORNING HOURS.
BY LATE MORNING AND CONTINUING INTO THE AFTERNOON LOW LEVEL LAPSE
RATES BECOME VERY STEEP. THE RUC ALONG WITH OTHER MODELS SHOW A
RESPECTABLE VORT MAX ROTATING THROUGH THE AREA WHICH SHOULD INDUCE
SHSN FROM LATE MORNING THROUGH THE AFTERNOON HOURS. THE STEEP LAPSE
RATES WILL ALSO ALLOW HIGHER MOMENTUM AIR TO MIX DOWN RESULTING IN
BRISK IF NOT WINDY CONDITIONS.
ADDITIONAL SNOW ACCUMULATIONS AFTER 12Z SHOULD BE GENERALLY ONE HALF
INCH OR LESS.
TONIGHT...LOW LEVEL LAPSE RATES REMAIN QUITE STEEP WITH NO
STABILIZATION OCCURRING UNTIL ROUGHLY SUNRISE. ADD INTO THIS
CHANNELED VORTICITY WITH SOME CYCLONIC FLOW ACROSS THE AREA AND
CLOUDS MAY BE SLOW TO BREAK UP OR CLEAR OUT. THEREFORE...WILL HOLD
ONTO THE CLOUDS LONGER. ADDITIONALLY...SINCE SUNSET IS NOW CLOSER TO
6 PM THERE MAY BE SOME LINGERING FLURRIES OR DECAYING SHSN INTO THE
EARLY EVENING ACROSS THE EASTERN CWFA.
.08..
LONG TERM...
AN ACTIVE WEATHER REGIME WILL BE IN PLACE THROUGH THE LONG TERM
FORECAST. MODELS ARE IN AGREEMENT WITH A POTENT S/W PASSING TO OUR
NORTH LATE IN THE WEEKEND WITH A SIGNIFICANT TROF MOVING THROUGH
MID-WEEK.
FOR SATURDAY AND SATURDAY NIGHT...A HIGH PRESSURE RIDGE WILL BE OVER
THE AREA EARLY SATURDAY. THE RIDGE IS PUSHED EAST BY SATURDAY
EVENING AS S/W ENERGY MOVES OUT OF THE PAC NW INTO THE NORTHERN
PLAINS...DRIVING A SURFACE LOW INTO THE EASTERN DAKOTAS BY SUNDAY
MORNING. EXPECT DRY CONDITIONS DURING THE PERIOD SO TEMPERATURES
WILL BE THE MAIN CONCERN. LIMITED MIXING IN THE RIDGE AXIS
SATURDAY WILL LIMIT HIGHS. THERE MAY ALSO BE SOME RESIDUAL SNOW
COVER NORTH FROM THE CURRENT EVENT...SO WILL KEEP HIGHS IN THE
30S. MINS SATURDAY NIGHT WILL LIKELY OCCUR DURING THE EVENING AS
SOUTHERLY FLOW BEGINS INCREASING AHEAD OF THE NORTHERN PLAINS
SURFACE LOW. KEPT MINS AROUND 20 IN THE NORTHEAST WHERE BEST
COOLING POTENTIAL EXISTS WITH LIGHT WINDS IN THE EVENING AND
POSSIBLY SOME SNOW STILL ON THE GROUND. LOWS IN THE SOUTHWEST
SHOULD OCCUR FAIRLY EARLY IN THE EVENING...SO KEPT THAT AREA IN THE
LOW 30S. TEMPS SHOULD STEADY OUT OR RISE SOME DURING THE LATE
EVENING AND OVERNIGHT HOURS.
SUNDAY AND SUNDAY NIGHT THE NORTHERN PLAINS S/W AND SURFACE LOW
WILL CROSS MN AND MOVE INTO THE GREAT LAKES BY MONDAY MORNING. A
COLD FRONT BEHIND THE SYSTEM WILL DROP SOUTHEAST THROUGH THE
FORECAST AREA SUNDAY NIGHT. WITH LIMITED MOISTURE AND THE BEST
FORCING STAYING WELL NORTH OF THE CWFA...HAVE REMOVED THE LOW POPS
FROM THE NORTH. HIGHS IN THE 40S NORTH TO MID 50S FAR SOUTH LOOK
REASONABLE WITH THE FORECAST AREA IN THE WARM SECTOR SUNDAY...AND
GUSTY SOUTHWEST WINDS TO AID DEEP MIXING. THE COLD FRONT WILL MOVE
THROUGH SUNDAY NIGHT...BUT THE AIR BEHIND THE FRONT IS NOT THAT
COLD...SO KEPT MINS IN THE MID 20S TO LOW 30S.
THE NEXT SYSTEM TO IMPACT THE AREA IS A SIGNIFICANT TROF THAT IS
EXPECTED TO MOVE INTO THE CA COAST MONDAY AND HEAD EAST INTO THE
PLAINS BY TUESDAY EVENING. THE MODELS WERE COMING INTO DECENT
AGREEMENT ON THE 24/00Z RUN WITH THIS SYSTEM TAKING A MORE
NORTHERN TRACK...LIFTING THE SURFACE LOW THROUGH NW IA TUESDAY
NIGHT AND INTO THE GREAT LAKES BY LATE WEDNESDAY. WITH GOOD
AGREEMENT AMONG THE LONG RANGE MODELS THE BLENDED GUIDANCE HAS
WARMED TEMPERATURES UP CONSIDERABLY MONDAY NIGHT THROUGH
WEDNESDAY. HAVE EVEN BUMPED UP TEMPERATURES A FEW DEGREES FROM
GUIDANCE MONDAY NIGHT AND TUESDAY WHEN IT APPEARS WE WILL BE IN
THE WARM SECTOR. THE SYSTEM SHOULD HAVE SOME GULF MOISTURE TO WORK
WITH AS IT MOVES THROUGH THE MID MS VALLEY SO MAINTAINED HIGH
CHANCE OR LIKELY POPS TUESDAY INTO WEDNESDAY. SOME THUNDERSTORMS
CANNOT BE RULED OUT FOR TUESDAY NIGHT WHEN THE BEST FORCING WILL
LIFT THROUGH THE AREA. HOWEVER...I DID NOT MENTION ANY THUNDER
YET...SINCE THERE IS STILL POTENTIAL FOR THE MODEL SOLUTIONS TO
VARY. STRONG WEST TO NORTHWEST WINDS WILL USHER IN COLDER AIR LATE
TUESDAY NIGHT AND WEDNESDAY AS THE OCCLUDED SYSTEM LIFTS NORTHEAST
THROUGH WI AND INTO THE GREAT LAKES. WITH THE COLD AIR MOVING BACK
IN ANY LINGERING PRECIP WILL MIX WITH OR CHANGE TO SNOW. BY
THURSDAY TEMPERATURES SHOULD BE BACK TO NEAR NORMAL. ..DLF..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR
BENTON-BUCHANAN-CEDAR-CLINTON-DELAWARE-DUBUQUE-IOWA-JACKSON-
JOHNSON-JONES-LINN-MUSCATINE-SCOTT.
IL...WINTER WEATHER ADVISORY UNTIL 6 AM CST EARLY THIS MORNING FOR
CARROLL-JO DAVIESS-ROCK ISLAND-STEPHENSON.
WINTER WEATHER ADVISORY UNTIL 8 AM CST THIS MORNING FOR BUREAU-
PUTNAM.
WINTER WEATHER ADVISORY UNTIL 7 AM CST THIS MORNING FOR HENRY IL-
WHITESIDE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
932 AM EST FRI FEB 24 2012
.SYNOPSIS...
LOW PRESSURE OVER LAKE ERIE THIS MORNING WILL MOVE TO NORTHERN NEW
YORK THIS AFTERNOON WITH RAIN SHOWERS EARLY CHANGING TO SNOW
SHOWERS THIS EVENING. IT WILL TURN VERY WINDY AND MUCH COLDER
BEHIND A STRONG COLD FRONT THIS AFTERNOON WITH BLUSTERY AND COLD
CONDITIONS TONIGHT INTO SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
15Z...ONLY MINOR ADJUSTMENTS TO TEMPERATURES BASED ON CURRENT READINGS.
AT 8AM...MADE UPDATES TO EARLY MORNING TEMPERATURES AND SLOWED
TEMPERATURE DROP BEHIND THE COLD FRONT THIS AFTERNOON BASED OFF OF
THE MOST RECENT OBSERVATIONS AND RUC MODEL TRENDS. PUSHED SLIGHT
CHANCE POPS BACK AN HOUR OR SO AND ADJUSTED SKY COVER AS SOME
AREAS WILL SEE SUN THIS MORNING AS A DRY SLOT CROSSES.
SURFACE CENTERED OVER LAKE ERIE WILL BRING A BRIEF SURGE OF WARM
AIR AHEAD OF THE COLD FRONT AS IT APPROACHES FROM THE WEST.
TEMPS WARMING INTO THE 50S ACROSS THE AREA AND POSSIBLY THE 60S
ACROSS NORTH- CENTRAL WV THIS MORNING BEFORE A COLD FRONT
ARRIVES. THE COLD FRONT WILL SWING UNDERNEATH THE LOW AND BRING
MUCH COLDER TEMPERATURES BY THIS EVENING. THE PRESSURE GRADIENT
TIGHTENS BEHIND THE FRONT BETWEEN 18Z AND 00Z ACROSS THE AREA.
BUFKIT MOMENTUM TRANSFER STILL SUPPORT WIND GUSTS TO 50 MPH ACROSS
THE LOWLANDS AND UP TO 60 MPH FOR THE RIDGES. THUS, WIND ADVISORY
AND HIGH WIND WARNING REMAIN IN PLACE.
TONIGHT...RAIN SHOWERS WILL TRANSITION TO SNOW SHOWERS THIS
EVENING INTO TONIGHT AS TEMPERATURES FALL THROUGH THE 30S. WINDS
WILL CONTINUE TO GUST TO NEAR ADVISORY CRITERIA FOR WESTERN
PA, NORTHERN WV, AND WESTERN MD BEFORE MIDNIGHT. GUSTS WILL BEGIN
TO DIMINISH AFTER MIDNIGHT, ALTHOUGH STILL AT 20 TO 30 MPH BY
DAWN. WESTERLY LOW-LEVEL FLOW IS ANTICIPATED TO BECOME WEST-
NORTHWESTERLY BY DAWN. WITH 850MB TEMPS JUST SHORT OF 13C
DIFFERENTIAL FOR LAKE EFFECT AND MORE WESTERLY COMPONENT TO FLOW,
BELIEVE BEST ACCUMULATIONS OF 1 TO 3 INCHES OVERNIGHT WILL BE
POSSIBLE ACROSS THE EASTERN RIDGES WITH AROUND AN INCH ELSEWHERE.
OVERNIGHT LOWS ARE A MAV/MET BLEND.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
GFS/NAM/CANADIAN ARE IN AGREEMENT THAT A COLD LOW-LEVEL
NORTHWESTERLY FLOW WILL CONTINUE ACROSS THE AREA AND ALLOW FOR
THE CHANCE OF SNOW SHOWERS ACROSS THE LOWLANDS WITH LIKELY POPS
FOR THE LAKE EFFECT ZONES AND EASTERN RIDGES. SNOW SHOWERS WILL
DIMINISH ON SATURDAY NIGHT AS LOW-LEVEL RIDGING AND DRY AIR BUILD
INTO THE AREA. ADDITIONAL SNOW ACCUMULATION OF 1 TO 2 INCHES IS
EXPECTED ACROSS THE EASTERN RIDGES WITH GENERALLY LESS THAN INCH
ELSEWHERE. WITH 2 TO 5 INCHES POSSIBLE FROM FRIDAY NIGHT INTO
SATURDAY ACROSS THE HIGHEST ELEVATIONS, HAVE MENTIONED THIS IN
HWO. TEMPERATURES WILL BE AROUND 5 DEGREES BELOW NORMAL THROUGH
THIS PERIOD.
THERE IS OPERATIONAL MODEL AGREEMENT THAT HIGH PRESSURE PASSING
SOUTH OF THE AREA WILL ALLOW FOR A DRY SUNDAY ACROSS THE AREA WITH
ABUNDANT SUNSHINE. THIS WILL ALLOW TEMPS TO MODERATE CLOSER TO
SEASONAL NORMS BY THE END OF THE WEEKEND.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
HIGH PRESSURE WILL MAINTAIN DRY AND ABOVE SEASONABLE CONDITIONS FOR
THE FIRST HALF OF THE LONG TERM PERIOD AS AN UPPER LEVEL SHORTWAVE
CROSSES THE NORTHERN GREAT LAKES MONDAY. BOTH THE ECMWF AND GFS HAVE
THIS WAVE AND IT`S ATTENDANT SURFACE LOW PRESSURE SYSTEM STRETCH A
FRONT JUST ACROSS THE LOWER GREAT LAKES. THIS FRONT THEN BECOMES A
MECHANISM FOR WHICH ADDITIONAL WAVES WILL RIDE ALONG...SIMILAR TO
TODAY`S LOW PRESSURE SYSTEM.
WHILE TIMING AND STRENGTH ISSUES BEGIN TO DEVELOP BETWEEN THE
MODELS...BOTH THE GFS/ECMWF DEVELOP A LOW THAT IS PROGGED TO
APPROACH THE REGION TUESDAY NIGHT AND WEDNESDAY BRINGING RAIN
WEDNESDAY AND A CHANGE TO SNOW SHOWERS FOR THURSDAY.
WITH DECENT MODEL CONSENSUS THROUGH THE PERIOD...KEPT A BLEND OF THE
GFS/ECMWF WHICH IS CLOSE TO HPC GUIDANCE NUMBERS. THIS MAINTAINS
TEMPERATURES ABOUT 5-10 DEGREES ABOVE NORMAL MONDAY THROUGH
WEDNESDAY FOLLOWED BY A RETURN TO SEASONABLE LEVELS BY LATE
THURSDAY.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
MVFR AND TEMPO IFR CONDITIONS WILL CONTINUE THIS MORNING AS
CLEARING SKIES HAVE ALLOWED FOR SOME FOG AND LOW STRATUS TO
DEVELOP. MOST PORTS SHOULD RETURN TO VFR AS THE COLD FRONT
APPROACHES AROUND 10AM.
WINDS WILL BE THE MAIN AVIATION HAZARD FOR FRIDAY.
NAM MODEL PROFILES SHOW WINDS INCREASING IN SPEED TO 40 KTS AT ABOVE
2 KFT AGL LATE TONIGHT, WHILE WINDS IN THE STABLE SURFACE LAYER
REMAIN LESS THAN 10 KTS. HENCE EXPECT LOW LEVEL WIND SHEAR TO
DEVELOP WITH THE WARM FRONTAL PASSAGE 10Z-14Z.
DURING THE COLD FRONTAL PASSAGE, 13Z-18Z, VERTICAL MIXING WILL HELP
SOUTHWEST WINDS TO GUST OVER 30 KTS. POST FRONTAL WINDS ALOFT WILL BE
FASTER, HENCE SURFACE WIND GUSTS MAY PEAK AT OVER 40 KTS, 18Z-03Z.
OUTLOOK...FRIDAY NIGHT THROUGH TUESDAY...
A PROLONGED PERIOD OF RESTRICTIONS LIKELY WITH POST-SYSTEM
LAKE-ENHANCED SNOW SHOWERS FRIDAY NIGHT AND SATURDAY, PARTICULARLY
NORTH AND NEAR THE MOUNTAINS. VFR SUNDAY INTO TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR MDZ001.
OH...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR OHZ039>041-
048>050-057>059-068-069.
PA...WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR PAZ007>009-
013>016-020>023-029-031-073-075.
HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR PAZ074-076.
WV...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR WVZ001>004-012.
WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR WVZ021-022.
HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
847 AM EST FRI FEB 24 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE FROM OHIO INTO THE EASTERN GREAT LAKES
TODAY WITH RAIN SHOWERS EARLY CHANGING TO SNOW SHOWERS THIS
EVENING. IT WILL TURN VERY WINDY AND MUCH COLDER BEHIND A STRONG
COLD FRONT THIS AFTERNOON WITH BLUSTERY AND COLD CONDITIONS
TONIGHT INTO SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AT 8AM...MADE UPDATES TO EARLY MORNING TEMPERATURES AND
SLOWED TEMPERATURE DROP BEHIND THE COLD FRONT THIS AFTERNOON
BASED OFF OF THE MOST RECENT OBSERVATIONS AND RUC MODEL TRENDS.
PUSHED SLIGHT CHANCE POPS BACK AN HOUR OR SO AND ADJUSTED SKY
COVER AS SOME AREAS WILL SEE SUN THIS MORNING AS A DRY SLOT
CROSSES.
PREVIOUS DISCUSSION FOLLOWS...
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES A 500MB TROUGH AXIS
CENTERED ACROSS ILLINOIS WITH THE UPPER OHIO VALLEY IN A
SOUTHWESTERLY FLOW AHEAD OF THIS FEATURE. AT THE SURFACE, A 994MB
LOW IS CENTERED ACROSS SOUTHERN OHIO. A WARM FRONT EXTENDS EAST OF
THIS FEATURE ACROSS CENTRAL WEST VIRGINIA. A STRONG COLD FRONT
EXTENDS SOUTHWEST OF THIS FEATURE ACROSS THE TENNESSEE VALLEY.
LINGERING SHOWERS THIS MORNING ARE CONFINED TO THE SOUTHEASTERN
RIDGES.
TODAY...THE SURFACE LOW WILL PASS JUST WEST OF THE AREA THIS
MORNING AND BE CENTERED OVER LAKE ERIE BY 18Z. THIS WILL BRING A
BRIEF SURGE OF WARM AIR AHEAD OF THE COLD FRONT AS IT APPROACHES
FROM THE WEST. LAMP/HRRR SUPPORT TEMPS WARMING TEMPS INTO THE 50S
ACROSS THE AREA AND POSSIBLY THE 60S ACROSS NORTH-CENTRAL WV
BEFORE A COLD FRONT ARRIVES. THE COLD FRONT WILL SWING UNDERNEATH
THE LOW AND BRING MUCH COLDER TEMPERATURES BY THIS EVENING. THE
PRESSURE GRADIENT TIGHTENS BEHIND THE FRONT BETWEEN 18Z AND 00Z
ACROSS THE AREA. BUFKIT MOMENTUM TRANSFER STILL SUPPORT WIND GUSTS
TO 50 MPH ACROSS THE LOWLANDS AND UP TO 60 MPH FOR THE RIDGES.
THUS, WIND ADVISORY AND HIGH WIND WARNING REMAIN IN PLACE.
TONIGHT...RAIN SHOWERS WILL TRANSITION TO SNOW SHOWERS THIS
EVENING INTO TONIGHT AS TEMPERATURES FALL THROUGH THE 30S. WINDS
WILL CONTINUE TO GUST TO NEAR ADVISORY CRITERIA FOR WESTERN
PA, NORTHERN WV, AND WESTERN MD BEFORE MIDNIGHT. GUSTS WILL BEGIN
TO DIMINISH AFTER MIDNIGHT, ALTHOUGH STILL AT 20 TO 30 MPH BY
DAWN. WESTERLY LOW-LEVEL FLOW IS ANTICIPATED TO BECOME WEST-
NORTHWESTERLY BY DAWN. WITH 850MB TEMPS JUST SHORT OF 13C
DIFFERENTIAL FOR LAKE EFFECT AND MORE WESTERLY COMPONENT TO FLOW,
BELIEVE BEST ACCUMULATIONS OF 1 TO 3 INCHES OVERNIGHT WILL BE
POSSIBLE ACROSS THE EASTERN RIDGES WITH AROUND AN INCH ELSEWHERE.
OVERNIGHT LOWS ARE A MAV/MET BLEND, ALTHOUGH COOLER, STILL AROUND
5 DEGREES ABOVE CLIMATOLOGY.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
GFS/NAM/CANADIAN ARE IN AGREEMENT THAT A COLD LOW-LEVEL
NORTHWESTERLY FLOW WILL CONTINUE ACROSS THE AREA AND ALLOW FOR
THE CHANCE OF SNOW SHOWERS ACROSS THE LOWLANDS WITH LIKELY POPS
FOR THE LAKE EFFECT ZONES AND EASTERN RIDGES. SNOW SHOWERS WILL
DIMINISH ON SATURDAY NIGHT AS LOW-LEVEL RIDGING AND DRY AIR BUILD
INTO THE AREA. ADDITIONAL SNOW ACCUMULATION OF 1 TO 2 INCHES IS
EXPECTED ACROSS THE EASTERN RIDGES WITH GENERALLY LESS THAN INCH
ELSEWHERE. WITH 2 TO 5 INCHES POSSIBLE FROM FRIDAY NIGHT INTO
SATURDAY ACROSS THE HIGHEST ELEVATIONS, HAVE MENTIONED THIS IN
HWO. TEMPERATURES WILL BE AROUND 5 DEGREES BELOW NORMAL THROUGH
THIS PERIOD.
THERE IS OPERATIONAL MODEL AGREEMENT THAT HIGH PRESSURE PASSING
SOUTH OF THE AREA WILL ALLOW FOR A DRY SUNDAY ACROSS THE AREA WITH
ABUNDANT SUNSHINE. THIS WILL ALLOW TEMPS TO MODERATE CLOSER TO
SEASONAL NORMS BY THE END OF THE WEEKEND.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
HIGH PRESSURE WILL MAINTAIN DRY AND ABOVE SEASONABLE CONDITIONS FOR
THE FIRST HALF OF THE LONG TERM PERIOD AS AN UPPER LEVEL SHORTWAVE
CROSSES THE NORTHERN GREAT LAKES MONDAY. BOTH THE ECMWF AND GFS HAVE
THIS WAVE AND IT`S ATTENDANT SURFACE LOW PRESSURE SYSTEM STRETCH A
FRONT JUST ACROSS THE LOWER GREAT LAKES. THIS FRONT THEN BECOMES A
MECHANISM FOR WHICH ADDITIONAL WAVES WILL RIDE ALONG...SIMILAR TO
TODAY`S LOW PRESSURE SYSTEM.
WHILE TIMING AND STRENGTH ISSUES BEGIN TO DEVELOP BETWEEN THE
MODELS...BOTH THE GFS/ECMWF DEVELOP A LOW THAT IS PROGGED TO
APPROACH THE REGION TUESDAY NIGHT AND WEDNESDAY BRINGING RAIN
WEDNESDAY AND A CHANGE TO SNOW SHOWERS FOR THURSDAY.
WITH DECENT MODEL CONSENSUS THROUGH THE PERIOD...KEPT A BLEND OF THE
GFS/ECMWF WHICH IS CLOSE TO HPC GUIDANCE NUMBERS. THIS MAINTAINS
TEMPERATURES ABOUT 5-10 DEGREES ABOVE NORMAL MONDAY THROUGH
WEDNESDAY FOLLOWED BY A RETURN TO SEASONABLE LEVELS BY LATE
THURSDAY.
&&
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
MVFR AND TEMPO IFR CONDITIONS WILL CONTINUE THIS MORNING AS
CLEARING SKIES HAVE ALLOWED FOR SOME FOG AND LOW STRATUS TO
DEVELOP. MOST PORTS SHOULD RETURN TO VFR AS THE COLD FRONT
APPROACHES AROUND 10AM.
WINDS WILL BE THE MAIN AVIATION HAZARD FOR FRIDAY.
NAM MODEL PROFILES SHOW WINDS INCREASING IN SPEED TO 40 KTS AT ABOVE
2 KFT AGL LATE TONIGHT, WHILE WINDS IN THE STABLE SURFACE LAYER
REMAIN LESS THAN 10 KTS. HENCE EXPECT LOW LEVEL WIND SHEAR TO
DEVELOP WITH THE WARM FRONTAL PASSAGE 10Z-14Z.
DURING THE COLD FRONTAL PASSAGE, 13Z-18Z, VERTICAL MIXING WILL HELP
SOUTHWEST WINDS TO GUST OVER 30 KTS. POSTFRONTAL WINDS ALOFT WILL BE
FASTER, HENCE SURFACE WIND GUSTS MAY PEAK AT OVER 40 KTS, 18Z-03Z.
OUTLOOK...FRIDAY NIGHT THROUGH TUESDAY...
A PROLONGED PERIOD OF RESTRICTIONS LIKELY WITH POST-SYSTEM
LAKE-ENHANCED SNOW SHOWERS FRIDAY NIGHT AND SATURDAY, PARTICULARLY
NORTH AND NEAR THE MOUNTAINS. VFR SUNDAY INTO TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR MDZ001.
OH...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR OHZ039>041-
048>050-057>059-068-069.
PA...WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR PAZ007>009-
013>016-020>023-029-031-073-075.
HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR PAZ074-076.
WV...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR WVZ001>004-012.
WIND ADVISORY UNTIL 10 PM EST THIS EVENING FOR WVZ021-022.
HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
639 AM EST FRI FEB 24 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE FROM OHIO INTO THE EASTERN GREAT LAKES
TODAY WITH RAIN SHOWERS EARLY CHANGING TO SNOW SHOWERS THIS
EVENING. IT WILL TURN VERY WINDY AND MUCH COLDER BEHIND A STRONG
COLD FRONT THIS AFTERNOON WITH BLUSTERY AND COLD CONDITIONS
TONIGHT INTO SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
A QUICK UPDATE HAS BEEN ISSUED THIS MORNING TO ADD PATCHY DENSE
FOG IN THE MOUNTAINS SOUTH OF THE MASON DIXON LINE.
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES A 500MB TROUGH AXIS
CENTERED ACROSS ILLINOIS WITH THE UPPER OHIO VALLEY IN A
SOUTHWESTERLY FLOW AHEAD OF THIS FEATURE. AT THE SURFACE, A
994MB LOW IS CENTERED ACROSS SOUTHERN OHIO. A WARM FRONT EXTENDS
EAST OF THIS FEATURE ACROSS CENTRAL WEST VIRGINIA. A STRONG COLD
FRONT EXTENDS SOUTHWEST OF THIS FEATURE ACROSS THE TENNESSEE
VALLEY. LINGERING SHOWERS THIS MORNING ARE CONFINED TO THE
SOUTHEASTERN RIDGES.
TODAY...THE SURFACE LOW WILL PASS JUST WEST OF THE AREA THIS
MORNING AND BE CENTERED OVER LAKE ERIE BY 18Z. THIS WILL BRING A
BRIEF SURGE OF WARM AIR AHEAD OF THE COLD FRONT AS IT APPROACHES
FROM THE WEST. LAMP/HRRR SUPPORT TEMPS WARMING TEMPS INTO THE 50S
ACROSS THE AREA AND POSSIBLY THE 60S ACROSS NORTH-CENTRAL WV
BEFORE A COLD FRONT ARRIVES. THE COLD FRONT WILL SWING UNDERNEATH
THE LOW AND BRING MUCH COLDER TEMPERATURES BY THIS EVENING. THE
PRESSURE GRADIENT TIGHTENS BEHIND THE FRONT BETWEEN 18Z AND 00Z
ACROSS THE AREA. BUFKIT MOMENTUM TRANSFER STILL SUPPORT WIND GUSTS
TO 50 MPH ACROSS THE LOWLANDS AND UP TO 60 MPH FOR THE RIDGES.
THUS, WIND ADVISORY AND HIGH WIND WARNING REMAIN IN PLACE.
TONIGHT...RAIN SHOWERS WILL TRANSITION TO SNOW SHOWERS THIS
EVENING INTO TONIGHT AS TEMPERATURES FALL THROUGH THE 30S. WINDS
WILL CONTINUE TO GUST TO NEAR ADVISORY CRITERIA FOR WESTERN
PA, NORTHERN WV, AND WESTERN MD BEFORE MIDNIGHT. GUSTS WILL BEGIN
TO DIMINISH AFTER MIDNIGHT, ALTHOUGH STILL AT 20 TO 30 MPH BY
DAWN. WESTERLY LOW-LEVEL FLOW IS ANTICIPATED TO BECOME WEST-
NORTHWESTERLY BY DAWN. WITH 850MB TEMPS JUST SHORT OF 13C
DIFFERENTIAL FOR LAKE EFFECT AND MORE WESTERLY COMPONENT TO FLOW,
BELIEVE BEST ACCUMULATIONS OF 1 TO 3 INCHES OVERNIGHT WILL BE
POSSIBLE ACROSS THE EASTERN RIDGES WITH AROUND AN INCH ELSEWHERE.
OVERNIGHT LOWS ARE A MAV/MET BLEND, ALTHOUGH COOLER, STILL AROUND
5 DEGREES ABOVE CLIMATOLOGY.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
GFS/NAM/CANADIAN ARE IN AGREEMENT THAT A COLD LOW-LEVEL
NORTHWESTERLY FLOW WILL CONTINUE ACROSS THE AREA AND ALLOW FOR
THE CHANCE OF SNOW SHOWERS ACROSS THE LOWLANDS WITH LIKELY POPS
FOR THE LAKE EFFECT ZONES AND EASTERN RIDGES. SNOW SHOWERS WILL
DIMINISH ON SATURDAY NIGHT AS LOW-LEVEL RIDGING AND DRY AIR BUILD
INTO THE AREA. ADDITIONAL SNOW ACCUMULATION OF 1 TO 2 INCHES IS
EXPECTED ACROSS THE EASTERN RIDGES WITH GENERALLY LESS THAN INCH
ELSEWHERE. WITH 2 TO 5 INCHES POSSIBLE FROM FRIDAY NIGHT INTO
SATURDAY ACROSS THE HIGHEST ELEVATIONS, HAVE MENTIONED THIS IN
HWO. TEMPERATURES WILL BE AROUND 5 DEGREES BELOW NORMAL THROUGH
THIS PERIOD.
THERE IS OPERATIONAL MODEL AGREEMENT THAT HIGH PRESSURE PASSING
SOUTH OF THE AREA WILL ALLOW FOR A DRY SUNDAY ACROSS THE AREA WITH
ABUNDANT SUNSHINE. THIS WILL ALLOW TEMPS TO MODERATE CLOSER TO
SEASONAL NORMS BY THE END OF THE WEEKEND.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
HIGH PRESSURE WILL MAINTAIN DRY AND ABOVE SEASONABLE CONDITIONS FOR
THE FIRST HALF OF THE LONG TERM PERIOD AS AN UPPER LEVEL SHORTWAVE
CROSSES THE NORTHERN GREAT LAKES MONDAY. BOTH THE ECMWF AND GFS HAVE
THIS WAVE AND IT`S ATTENDANT SURFACE LOW PRESSURE SYSTEM STRETCH A
FRONT JUST ACROSS THE LOWER GREAT LAKES. THIS FRONT THEN BECOMES A
MECHANISM FOR WHICH ADDITIONAL WAVES WILL RIDE ALONG...SIMILAR TO
TODAY`S LOW PRESSURE SYSTEM.
WHILE TIMING AND STRENGTH ISSUES BEGIN TO DEVELOP BETWEEN THE
MODELS...BOTH THE GFS/ECMWF DEVELOP A LOW THAT IS PROGGED TO
APPROACH THE REGION TUESDAY NIGHT AND WEDNESDAY BRINGING RAIN
WEDNESDAY AND A CHANGE TO SNOW SHOWERS FOR THURSDAY.
WITH DECENT MODEL CONSENSUS THROUGH THE PERIOD...KEPT A BLEND OF THE
GFS/ECMWF WHICH IS CLOSE TO HPC GUIDANCE NUMBERS. THIS MAINTAINS
TEMPERATURES ABOUT 5-10 DEGREES ABOVE NORMAL MONDAY THROUGH
WEDNESDAY FOLLOWED BY A RETURN TO SEASONABLE LEVELS BY LATE
THURSDAY.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
SHOWERS HAVE ENDED ACROSS ALL PORTS AS UPPER SHORT WAVE MOVES EAST
OF THE RIDGES. MOST LOCATIONS WILL MAINTAIN VFR FLIGHT CONDITIONS,
EXCEPT KFKL AND KDUJ WHICH CAN EXPECT PERIODS OF MVFR TO IFR CEILING
BEFORE DAYBREAK. CEILINGS IN THE NORTH WILL IMPROVE AFTER SUNRISE.
WINDS WILL BE THE MAIN AVIATION HAZARD FOR FRIDAY.
NAM MODEL PROFILES SHOW WINDS INCREASING IN SPEED TO 40 KTS AT ABOVE
2 KFT AGL LATE TONIGHT, WHILE WINDS IN THE STABLE SURFACE LAYER
REMAIN LESS THAN 10 KTS. HENCE EXPECT LOW LEVEL WIND SHEAR TO
DEVELOP WITH THE WARM FRONTAL PASSAGE 10Z-14Z.
DURING THE COLD FRONTAL PASSAGE, 13Z-18Z, VERTICAL MIXING WILL HELP
SOUTHWEST WINDS TO GUST OVER 30 KTS. POSTFRONTAL WINDS ALOFT WILL BE
FASTER, HENCE SURFACE WIND GUSTS MAY PEAK AT OVER 40 KTS, 18Z-03Z.
OUTLOOK...FRIDAY NIGHT THROUGH TUESDAY...
A PROLONGED PERIOD OF RESTRICTIONS LIKELY WITH POST-SYSTEM
LAKE-ENHANCED SNOW SHOWERS FRIDAY NIGHT AND SATURDAY, PARTICULARLY
NORTH AND NEAR THE MOUNTAINS. VFR SUNDAY INTO TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...HIGH WIND WARNING FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR MDZ001.
OH...WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM EST THIS EVENING
FOR OHZ039>041-048>050-057>059-068-069.
PA...WIND ADVISORY FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR PAZ007>009-013>016-020>023-029-031-073-075.
HIGH WIND WARNING FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR PAZ074-076.
WV...WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM EST THIS EVENING
FOR WVZ001>004-012.
WIND ADVISORY FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR WVZ021-022.
HIGH WIND WARNING FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
557 AM EST FRI FEB 24 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE FROM OHIO INTO THE EASTERN GREAT LAKES
TODAY WITH RAIN SHOWERS EARLY CHANGING TO SNOW SHOWERS THIS
EVENING. IT WILL TURN VERY WINDY AND MUCH COLDER BEHIND A STRONG
COLD FRONT THIS AFTERNOON WITH BLUSTERY AND COLD CONDITIONS
TONIGHT INTO SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
A QUICK UPDATE HAS BEEN ISSUED THIS MORNING TO ACCOUNT FOR AN AREA
OF CLEARING CROSSING THE AREA AND TO REMOVE POPS EARLY.
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES A 500MB TROUGH AXIS
CENTERED ACROSS ILLINOIS WITH THE UPPER OHIO VALLEY IN A
SOUTHWESTERLY FLOW AHEAD OF THIS FEATURE. AT THE SURFACE, A
994MB LOW IS CENTERED ACROSS SOUTHERN OHIO. A WARM FRONT EXTENDS
EAST OF THIS FEATURE ACROSS CENTRAL WEST VIRGINIA. A STRONG COLD
FRONT EXTENDS SOUTHWEST OF THIS FEATURE ACROSS THE TENNESSEE
VALLEY. LINGERING SHOWERS THIS MORNING ARE CONFINED TO THE
SOUTHEASTERN RIDGES.
TODAY...THE SURFACE LOW WILL PASS JUST WEST OF THE AREA THIS
MORNING AND BE CENTERED OVER LAKE ERIE BY 18Z. THIS WILL BRING A
BRIEF SURGE OF WARM AIR AHEAD OF THE COLD FRONT AS IT APPROACHES
FROM THE WEST. LAMP/HRRR SUPPORT TEMPS WARMING TEMPS INTO THE 50S
ACROSS THE AREA AND POSSIBLY THE 60S ACROSS NORTH-CENTRAL WV
BEFORE A COLD FRONT ARRIVES. THE COLD FRONT WILL SWING UNDERNEATH
THE LOW AND BRING MUCH COLDER TEMPERATURES BY THIS EVENING. THE
PRESSURE GRADIENT TIGHTENS BEHIND THE FRONT BETWEEN 18Z AND 00Z
ACROSS THE AREA. BUFKIT MOMENTUM TRANSFER STILL SUPPORT WIND GUSTS
TO 50 MPH ACROSS THE LOWLANDS AND UP TO 60 MPH FOR THE RIDGES.
THUS, WIND ADVISORY AND HIGH WIND WARNING REMAIN IN PLACE.
TONIGHT...RAIN SHOWERS WILL TRANSITION TO SNOW SHOWERS THIS
EVENING INTO TONIGHT AS TEMPERATURES FALL THROUGH THE 30S. WINDS
WILL CONTINUE TO GUST TO NEAR ADVISORY CRITERIA FOR WESTERN
PA, NORTHERN WV, AND WESTERN MD BEFORE MIDNIGHT. GUSTS WILL BEGIN
TO DIMINISH AFTER MIDNIGHT, ALTHOUGH STILL AT 20 TO 30 MPH BY
DAWN. WESTERLY LOW-LEVEL FLOW IS ANTICIPATED TO BECOME WEST-
NORTHWESTERLY BY DAWN. WITH 850MB TEMPS JUST SHORT OF 13C
DIFFERENTIAL FOR LAKE EFFECT AND MORE WESTERLY COMPONENT TO FLOW,
BELIEVE BEST ACCUMULATIONS OF 1 TO 3 INCHES OVERNIGHT WILL BE
POSSIBLE ACROSS THE EASTERN RIDGES WITH AROUND AN INCH ELSEWHERE.
OVERNIGHT LOWS ARE A MAV/MET BLEND, ALTHOUGH COOLER, STILL AROUND
5 DEGREES ABOVE CLIMATOLOGY.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
GFS/NAM/CANADIAN ARE IN AGREEMENT THAT A COLD LOW-LEVEL
NORTHWESTERLY FLOW WILL CONTINUE ACROSS THE AREA AND ALLOW FOR
THE CHANCE OF SNOW SHOWERS ACROSS THE LOWLANDS WITH LIKELY POPS
FOR THE LAKE EFFECT ZONES AND EASTERN RIDGES. SNOW SHOWERS WILL
DIMINISH ON SATURDAY NIGHT AS LOW-LEVEL RIDGING AND DRY AIR BUILD
INTO THE AREA. ADDITIONAL SNOW ACCUMULATION OF 1 TO 2 INCHES IS
EXPECTED ACROSS THE EASTERN RIDGES WITH GENERALLY LESS THAN INCH
ELSEWHERE. WITH 2 TO 5 INCHES POSSIBLE FROM FRIDAY NIGHT INTO
SATURDAY ACROSS THE HIGHEST ELEVATIONS, HAVE MENTIONED THIS IN
HWO. TEMPERATURES WILL BE AROUND 5 DEGREES BELOW NORMAL THROUGH
THIS PERIOD.
THERE IS OPERATIONAL MODEL AGREEMENT THAT HIGH PRESSURE PASSING
SOUTH OF THE AREA WILL ALLOW FOR A DRY SUNDAY ACROSS THE AREA WITH
ABUNDANT SUNSHINE. THIS WILL ALLOW TEMPS TO MODERATE CLOSER TO
SEASONAL NORMS BY THE END OF THE WEEKEND.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
HIGH PRESSURE WILL MAINTAIN DRY AND ABOVE SEASONABLE CONDITIONS FOR
THE FIRST HALF OF THE LONG TERM PERIOD AS AN UPPER LEVEL SHORTWAVE
CROSSES THE NORTHERN GREAT LAKES MONDAY. BOTH THE ECMWF AND GFS HAVE
THIS WAVE AND IT`S ATTENDANT SURFACE LOW PRESSURE SYSTEM STRETCH A
FRONT JUST ACROSS THE LOWER GREAT LAKES. THIS FRONT THEN BECOMES A
MECHANISM FOR WHICH ADDITIONAL WAVES WILL RIDE ALONG...SIMILAR TO
TODAY`S LOW PRESSURE SYSTEM.
WHILE TIMING AND STRENGTH ISSUES BEGIN TO DEVELOP BETWEEN THE
MODELS...BOTH THE GFS/ECMWF DEVELOP A LOW THAT IS PROGGED TO
APPROACH THE REGION TUESDAY NIGHT AND WEDNESDAY BRINGING RAIN
WEDNESDAY AND A CHANGE TO SNOW SHOWERS FOR THURSDAY.
WITH DECENT MODEL CONSENSUS THROUGH THE PERIOD...KEPT A BLEND OF THE
GFS/ECMWF WHICH IS CLOSE TO HPC GUIDANCE NUMBERS. THIS MAINTAINS
TEMPERATURES ABOUT 5-10 DEGREES ABOVE NORMAL MONDAY THROUGH
WEDNESDAY FOLLOWED BY A RETURN TO SEASONABLE LEVELS BY LATE
THURSDAY.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
SHOWERS HAVE ENDED ACROSS ALL PORTS AS UPPER SHORT WAVE MOVES EAST
OF THE RIDGES. MOST LOCATIONS WILL MAINTAIN VFR FLIGHT CONDITIONS,
EXCEPT KFKL AND KDUJ WHICH CAN EXPECT PERIODS OF MVFR TO IFR CEILING
BEFORE DAYBREAK. CEILINGS IN THE NORTH WILL IMPROVE AFTER SUNRISE.
WINDS WILL BE THE MAIN AVIATION HAZARD FOR FRIDAY.
NAM MODEL PROFILES SHOW WINDS INCREASING IN SPEED TO 40 KTS AT ABOVE
2 KFT AGL LATE TONIGHT, WHILE WINDS IN THE STABLE SURFACE LAYER
REMAIN LESS THAN 10 KTS. HENCE EXPECT LOW LEVEL WIND SHEAR TO
DEVELOP WITH THE WARM FRONTAL PASSAGE 10Z-14Z.
DURING THE COLD FRONTAL PASSAGE, 13Z-18Z, VERTICAL MIXING WILL HELP
SOUTHWEST WINDS TO GUST OVER 30 KTS. POSTFRONTAL WINDS ALOFT WILL BE
FASTER, HENCE SURFACE WIND GUSTS MAY PEAK AT OVER 40 KTS, 18Z-03Z.
OUTLOOK...FRIDAY NIGHT THROUGH TUESDAY...
A PROLONGED PERIOD OF RESTRICTIONS LIKELY WITH POST-SYSTEM
LAKE-ENHANCED SNOW SHOWERS FRIDAY NIGHT AND SATURDAY, PARTICULARLY
NORTH AND NEAR THE MOUNTAINS. VFR SUNDAY INTO TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...HIGH WIND WARNING FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR MDZ001.
OH...WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM EST THIS EVENING
FOR OHZ039>041-048>050-057>059-068-069.
PA...WIND ADVISORY FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR PAZ007>009-013>016-020>023-029-031-073-075.
HIGH WIND WARNING FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR PAZ074-076.
WV...WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM EST THIS EVENING
FOR WVZ001>004-012.
WIND ADVISORY FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR WVZ021-022.
HIGH WIND WARNING FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
513 AM EST FRI FEB 24 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE FROM OHIO INTO THE EASTERN GREAT LAKES
TODAY WITH RAIN SHOWERS EARLY CHANGING TO SNOW SHOWERS THIS
EVENING. IT WILL TURN VERY WINDY AND MUCH COLDER BEHIND A STRONG
COLD FRONT THIS AFTERNOON WITH BLUSTERY AND COLD CONDITIONS
TONIGHT INTO SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES A 500MB TROUGH AXIS
CENTERED ACROSS ILLINOIS WITH THE UPPER OHIO VALLEY IN A
SOUTHWESTERLY FLOW AHEAD OF THIS FEATURE. AT THE SURFACE, A
994MB LOW IS CENTERED ACROSS SOUTHERN OHIO. A WARM FRONT EXTENDS
EAST OF THIS FEATURE ACROSS CENTRAL WEST VIRGINIA. A STRONG COLD
FRONT EXTENDS SOUTHWEST OF THIS FEATURE ACROSS THE TENNESSEE
VALLEY. LINGERING SHOWERS THIS MORNING ARE CONFINED TO THE
SOUTHEASTERN RIDGES.
TODAY...THE SURFACE LOW WILL PASS JUST WEST OF THE AREA THIS
MORNING AND BE CENTERED OVER LAKE ERIE BY 18Z. THIS WILL BRING A
BRIEF SURGE OF WARM AIR AHEAD OF THE COLD FRONT AS IT APPROACHES
FROM THE WEST. LAMP/HRRR SUPPORT TEMPS WARMING TEMPS INTO THE 50S
ACROSS THE AREA AND POSSIBLY THE 60S ACROSS NORTH-CENTRAL WV
BEFORE A COLD FRONT ARRIVES. THE COLD FRONT WILL SWING UNDERNEATH
THE LOW AND BRING MUCH COLDER TEMPERATURES BY THIS EVENING. THE
PRESSURE GRADIENT TIGHTENS BEHIND THE FRONT BETWEEN 18Z AND 00Z
ACROSS THE AREA. BUFKIT MOMENTUM TRANSFER STILL SUPPORT WIND GUSTS
TO 50 MPH ACROSS THE LOWLANDS AND UP TO 60 MPH FOR THE RIDGES.
THUS, WIND ADVISORY AND HIGH WIND WARNING REMAIN IN PLACE.
TONIGHT...RAIN SHOWERS WILL TRANSITION TO SNOW SHOWERS THIS
EVENING INTO TONIGHT AS TEMPERATURES FALL THROUGH THE 30S. WINDS
WILL CONTINUE TO GUST TO NEAR ADVISORY CRITERIA FOR WESTERN
PA, NORTHERN WV, AND WESTERN MD BEFORE MIDNIGHT. GUSTS WILL BEGIN
TO DIMINISH AFTER MIDNIGHT, ALTHOUGH STILL AT 20 TO 30 MPH BY
DAWN. WESTERLY LOW-LEVEL FLOW IS ANTICIPATED TO BECOME WEST-
NORTHWESTERLY BY DAWN. WITH 850MB TEMPS JUST SHORT OF 13C
DIFFERENTIAL FOR LAKE EFFECT AND MORE WESTERLY COMPONENT TO FLOW,
BELIEVE BEST ACCUMULATIONS OF 1 TO 3 INCHES OVERNIGHT WILL BE
POSSIBLE ACROSS THE EASTERN RIDGES WITH AROUND AN INCH ELSEWHERE.
OVERNIGHT LOWS ARE A MAV/MET BLEND, ALTHOUGH COOLER, STILL AROUND
5 DEGREES ABOVE CLIMATOLOGY.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
GFS/NAM/CANADIAN ARE IN AGREEMENT THAT A COLD LOW-LEVEL
NORTHWESTERLY FLOW WILL CONTINUE ACROSS THE AREA AND ALLOW FOR
THE CHANCE OF SNOW SHOWERS ACROSS THE LOWLANDS WITH LIKELY POPS
FOR THE LAKE EFFECT ZONES AND EASTERN RIDGES. SNOW SHOWERS WILL
DIMINISH ON SATURDAY NIGHT AS LOW-LEVEL RIDGING AND DRY AIR BUILD
INTO THE AREA. ADDITIONAL SNOW ACCUMULATION OF 1 TO 2 INCHES IS
EXPECTED ACROSS THE EASTERN RIDGES WITH GENERALLY LESS THAN INCH
ELSEWHERE. WITH 2 TO 5 INCHES POSSIBLE FROM FRIDAY NIGHT INTO
SATURDAY ACROSS THE HIGHEST ELEVATIONS, HAVE MENTIONED THIS IN
HWO. TEMPERATURES WILL BE AROUND 5 DEGREES BELOW NORMAL THROUGH
THIS PERIOD.
THERE IS OPERATIONAL MODEL AGREEMENT THAT HIGH PRESSURE PASSING
SOUTH OF THE AREA WILL ALLOW FOR A DRY SUNDAY ACROSS THE AREA WITH
ABUNDANT SUNSHINE. THIS WILL ALLOW TEMPS TO MODERATE CLOSER TO
SEASONAL NORMS BY THE END OF THE WEEKEND.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
HIGH PRESSURE WILL MAINTAIN DRY AND ABOVE SEASONABLE CONDITIONS FOR
THE FIRST HALF OF THE LONG TERM PERIOD AS AN UPPER LEVEL SHORTWAVE
CROSSES THE NORTHERN GREAT LAKES MONDAY. BOTH THE ECMWF AND GFS HAVE
THIS WAVE AND IT`S ATTENDANT SURFACE LOW PRESSURE SYSTEM STRETCH A
FRONT JUST ACROSS THE LOWER GREAT LAKES. THIS FRONT THEN BECOMES A
MECHANISM FOR WHICH ADDITIONAL WAVES WILL RIDE ALONG...SIMILAR TO
TODAY`S LOW PRESSURE SYSTEM.
WHILE TIMING AND STRENGTH ISSUES BEGIN TO DEVELOP BETWEEN THE
MODELS...BOTH THE GFS/ECMWF DEVELOP A LOW THAT IS PROGGED TO
APPROACH THE REGION TUESDAY NIGHT AND WEDNESDAY BRINGING RAIN
WEDNESDAY AND A CHANGE TO SNOW SHOWERS FOR THURSDAY.
WITH DECENT MODEL CONSENSUS THROUGH THE PERIOD...KEPT A BLEND OF THE
GFS/ECMWF WHICH IS CLOSE TO HPC GUIDANCE NUMBERS. THIS MAINTAINS
TEMPERATURES ABOUT 5-10 DEGREES ABOVE NORMAL MONDAY THROUGH
WEDNESDAY FOLLOWED BY A RETURN TO SEASONABLE LEVELS BY LATE
THURSDAY.
&&
.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
SHOWERS HAVE ENDED ACROSS ALL PORTS AS UPPER SHORT WAVE MOVES EAST
OF THE RIDGES. MOST LOCATIONS WILL MAINTAIN VFR FLIGHT CONDITIONS,
EXCEPT KFKL AND KDUJ WHICH CAN EXPECT PERIODS OF MVFR TO IFR CEILING
BEFORE DAYBREAK. CEILINGS IN THE NORTH WILL IMPROVE AFTER SUNRISE.
WINDS WILL BE THE MAIN AVIATION HAZARD FOR FRIDAY.
NAM MODEL PROFILES SHOW WINDS INCREASING IN SPEED TO 40 KTS AT ABOVE
2 KFT AGL LATE TONIGHT, WHILE WINDS IN THE STABLE SURFACE LAYER
REMAIN LESS THAN 10 KTS. HENCE EXPECT LOW LEVEL WIND SHEAR TO
DEVELOP WITH THE WARM FRONTAL PASSAGE 10Z-14Z.
DURING THE COLD FRONTAL PASSAGE, 13Z-18Z, VERTICAL MIXING WILL HELP
SOUTHWEST WINDS TO GUST OVER 30 KTS. POSTFRONTAL WINDS ALOFT WILL BE
FASTER, HENCE SURFACE WIND GUSTS MAY PEAK AT OVER 40 KTS, 18Z-03Z.
OUTLOOK...FRIDAY NIGHT THROUGH TUESDAY...
A PROLONGED PERIOD OF RESTRICTIONS LIKELY WITH POST-SYSTEM
LAKE-ENHANCED SNOW SHOWERS FRIDAY NIGHT AND SATURDAY, PARTICULARLY
NORTH AND NEAR THE MOUNTAINS. VFR SUNDAY INTO TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...HIGH WIND WARNING FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR MDZ001.
OH...WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM EST THIS EVENING
FOR OHZ039>041-048>050-057>059-068-069.
PA...WIND ADVISORY FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR PAZ007>009-013>016-020>023-029-031-073-075.
HIGH WIND WARNING FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR PAZ074-076.
WV...WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM EST THIS EVENING
FOR WVZ001>004-012.
WIND ADVISORY FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR WVZ021-022.
HIGH WIND WARNING FROM 10 AM THIS MORNING TO 10 PM EST THIS
EVENING FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1045 AM EST FRI FEB 24 2012
.UPDATE...
ISSUED AT 1045 AM EST FRI FEB 24 2012
I HAVE UPDATED THE FORECAST PRODUCTS TO EXPAND THE WARNING
NORTHEAST TO INCLUDE OSCEOLA AND CLARE COUNTIES. WE HAVE RECEIVED
RELIABLE (THEY SENT PICTURES) REPORTS OF 10 TO 12 INCHES IN A
BAND FROM EVART TO HARRISON BY 8 AM. THE SNOW CONTINUES TO FALL
ACROSS THAT AREA AND SHOULD INTO EARLY THIS AFTERNOON SO IT MAKES
SENSE TO INCLUDE THEM IN A WARNING.
ELSEWHERE AND OTHERWISE THE FORECAST LOOKS TO BE ON TRACK. THE
DEFORMATION SNOW BANDS HAVE ROTATE SE INTO WESTERN AND CENTRAL
COUNTIES OF SOUTHWEST LOWER MICHIGAN. THE HRRR SUGGEST BY NOON
MOST OF THE MORE SIGNIFICANT SNOW WILL HAVE ENDED AND ONLY AND
INCH OR TWO SHOULD FALL THIS AFTERNOON.
LAKE EFFECT WILL DEVELOP THIS EVENING AND I COULD SEE 2 TO 4
INCHES FROM THAT TONIGHT INTO SATURDAY MORNING. WE MAY HAVE TO
EXPAND HEADLINES IN OUR SW MOST COUNTIES FOR THAT.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 441 AM EST FRI FEB 24 2012
FORECAST CONCERNS DEAL WITH THE LOW MOVING ACROSS THE NORTHERN
OHIO VALLEY. CHANGES TO THE FORECAST MAINLY INCLUDE DELAYING THE
STEADIER SNOWFALL UNTIL THIS MORNING AND TRIMMING ACCUMS A BIT.
THIS HAS RESULTED IN THE DOWNGRADE OF THE WARNING TO AN ADVISORY
FOR THE SRN TIER OF COUNTIES.
LATEST RADAR TRENDS SHOW AN INCREASE IN COVERAGE AND INTENSITY
OVER THE CWA. WE/VE ALREADY HAD A REPORT OF 2 INCHES IN AN HOUR
OVER THE NRN CWA. THIS IS A TYPICAL FGEN EVENT THAT IS SLOW TO
DEVELOP AND FEATURES MANY HOLES IN THE RADAR COVERAGE. HOWEVER THE
SHORT WAVE DRIVING THIS IS STRENGTHEN AND WE SHOULD SEE HEAVIER
SNOW BETWEEN NOW AND LATE MORNING. MODELS SHOW STRONG UVV/S IN
THE DGZ EARLY THIS MORNING. THUS...THE MORNING COMMUTE SHOULD BE
HEAVILY IMPACTED. THE EXCEPTION WILL BE THE FAR SE CWA WHERE
SNOWFALL MAY NOT BE AS MUCH AS EARLIER EXPECTED.
THE TROWAL IS SETTING UP FROM OTTAWA COUNTY NORTHEASTWARD TOWARD
SAGINAW BAY AND THIS SHOULD BE WHERE THE AXIS OF HEAVY SNOW
DEVELOPS. I WOULD NOT BE SURPRISED TO SEE AREAS THAT SEE TOTAL
ACCUMS AROUND 3 INCHES AND AREAS THAT SEE 8 INCHES ACROSS THE
CENTRAL CWA.
REGIONAL RADAR SHOWS MODERATE TO HEAVY SNOW EXTENDING SWWD TO NW
ILLINOIS. GIVEN THE SLOWER DEVELOPMENT OF THE EVENT...WE EXTENDED
THE HEADLINES THROUGH THE AFTERNOON. THE NRN ROW OF COUNTIES WILL
SEE TOTAL ACCUMS IN THE 3-6 INCH RANGE.
AS THE LOW MOVES EAST THIS AFTERNOON/EVENING...THE FGEN SNOW WILL
DIMINISH AND LAKE EFFECT SNOWS WILL DEVELOP. H8 TEMPS APPEAR
MARGINAL FOR LAKE EFFECT BUT MOISTURE IS FAIRLY DEEP AND SO THE
TRADITIONAL NW FLOW AREAS COULD SEE 2 OR 3 INCHES OF ADDITIONAL
SNOWFALL TONIGHT/SATURDAY.
.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 441 AM EST FRI FEB 24 2012
THE NEXT SYSTEM WILL BE A SFC LOW TRACKING FROM THE NRN PLAINS
ACROSS THE NRN GREAT LAKES REGION SUNDAY AND SUNDAY NIGHT. MOST OF
THE PCPN WITH THIS SYSTEM FALLS NEAR AND NORTH OF THE LOW TRACK SO
WILL CARRY ONLY LOW CHANCE POPS FOR A FEW LIGHT RAIN OR SNOW SHOWERS
IN NRN SECTIONS OF THE CWFA.
A VARIETY OF WEATHER CAN BE EXPECTED FROM A SLOW MOVING SYSTEM THAT
IS PROGGED TO TRACK FROM NEBRASKA TO MICHIGAN FOR TUESDAY AND
WEDNESDAY... THEN INTO NEW ENGLAND ON THURSDAY.
STRONG WARM ADVECTION AND GULF MOISTURE IN ADVANCE OF THE SFC LOW
SHOULD RESULT IN A MIXTURE OF WINTRY PCPN DEVELOPING TUESDAY OR
TUESDAY EVENING... FOLLOWED BY A QUICK CHANGEOVER TO PRIMARILY RAIN
LATE TUESDAY NIGHT AND WEDNESDAY MORNING.
STRONG COLD ADVECTION COMING AROUND THE SOUTH SIDE OF THE LOW AS IT
TRACKS INTO NRN LWR MI WILL BRING A CHANGEOVER BACK TO SNOW SHOWERS
WEDNESDAY AFTERNOON AND NIGHT. A FEW SNOW SHOWERS SHOULD CONTINUE
THURSDAY IN THE PERSISTENT CYCLONIC COLD ADVECTION PATTERN ON THE
BACK SIDE AS THE SFC LOW HEADS INTO NEW ENGLAND.
NO SIGNIFICANT SNOW IS EXPECTED BUT THERE COULD BE OVER A HALF INCH
OF RAIN IN SRN SECTIONS OF THE CWFA TUESDAY NIGHT AS STRONG LOW
LEVEL JET AND PWAT VALUES OVER ONE INCH IMPACT THE REGION.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 653 AM EST FRI FEB 24 2012
WIDESPREAD IFR/LIFR CONDITIONS IN SNOW THIS MORNING... WITH
CONDITIONS IMPROVING TO MVFR THIS AFTERNOON AS SNOW DIMINISHES.
GUSTY NE SFC WINDS TO 25 KTS THIS MORNING BECOMING NW THIS
AFTERNOON. SOME IFR LAKE EFFECT SNOW SHOWERS DEVELOPING AFTER 03Z
TONIGHT FOR MKG/AZO... POSSIBLY GRR/BTL AS WELL. MEANWHILE VFR
EXPECTED FARTHER EAST AT LAN AND JXN TONIGHT.
&&
.MARINE...
ISSUED AT 441 AM EST FRI FEB 24 2012
KEPT THE SCA GOING MAINLY FOR WINDS TODAY. AFTER THE LOW MOVES
PAST THIS AFTERNOON AND WINDS BACK TO THE NORTHWEST...WAVES WILL
INCREASE.
&&
.HYDROLOGY...
ISSUED AT 441 PM EST THU FEB 23 2012
TEMPS IN THE 30S DURING THE NEXT FEW DAYS WILL LIMIT THE MELTING
OF THE SNOW THAT FALLS TODAY. AS SUCH...RIVERS WILL BE SLOWER TO
RESPOND AND SHOULD REMAIN BELOW ACTION STAGE.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING UNTIL 5 PM EST THIS AFTERNOON FOR MIZ039-
040-043>046-050>052-056>059-064>067.
WINTER WEATHER ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR MIZ037-
038-071>074.
LM...SMALL CRAFT ADVISORY UNTIL 7 PM EST SATURDAY FOR LMZ844>849.
&&
$$
UPDATE...WDM
SHORT TERM...93
LONG TERM....MEADE
AVIATION...MEADE
MARINE...93
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
629 AM EST FRI FEB 24 2012
.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 521 AM EST FRI FEB 24 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A TROF OVER THE CNTRL
CONUS. A VIGOROUS LOOKING SHORTWAVE TRACKING E INTO IL WAS
SUPPORTING A BAND OF SNOW FROM ERN IA ACROSS SRN WI/NRN IL INTO LWR
MI. UPSTREAM....A SHORTWAVE TROF EXTENDS FROM SRN MANITOBA THRU THE
ERN DAKOTAS/WRN MN WITH VORT MAX APPARENT OVER SE MANITOBA. AT THE
SFC...OBS INDICATE ASSOCIATED WEAK SFC LOW N OF KINL WITH TROF
EXTENDING SE TOWARD WRN LAKE SUPERIOR...AND KDLH RADAR SHOWS A BAND
OF -SN ALONG THE TROF. CLOSER TO HOME...MOISTURE EXTENDING TO AROUND
6KFT PER FCST SOUNDINGS AND IMPLIED BY KMQT VAD WIND PROFILE ALONG
WITH 850MB TEMPS OF -9/-10C IS SUPPORTING FLURRIES/-SHSN OFF LAKE
SUPERIOR INTO NCNTRL UPPER MI. -SHSN TRENDS OVERNIGHT HAVE BEEN ODD
WITH UNORGANIZED SNOW AREAS DEVELOPING AND INTENSIFYING OVER THE
WATER ONLY TO PERSIST FOR A WHILE AND THEN RAPIDLY WEAKEN. SHORT
TERM FCST CONCERNS WILL REVOLVE AROUND SHORTWAVE TO THE NW...AND THE
AFFECTS IT WILL HAVE ON LAKE EFFECT LATER TODAY THRU TONIGHT.
00Z CWPL SOUNDING PROBABLY GIVES A DECENT REPRESENTATION OF AIR MASS
THAT WILL BE OVER THE WRN FCST AREA LATER TODAY/TONIGHT. IF SO...
850MB TEMPS WILL DROP A COUPLE OF DEGREES C AND COLUMN MOISTURE WILL
DEEPEN SIGNIFICANTLY. MODEL GUIDANCE IS IN GOOD AGREEMENT ON THIS
COOLING/MOISTENING. AT THE SAME...TIME WEAK DEEP LAYER FORCING WILL
OVERSPREAD WRN LAKE SUPERIOR/WRN UPPER MI IN ASSOCIATION WITH
AFOREMENTIONED SHORTWAVE TO THE NW. AT THE LOW LEVELS...THERE IS
GOOD AGREEMENT AMONG NUMEROUS MODELS THAT APPROACHING SFC TROF WILL
BASICALLY HANG UP OVER WRN LAKE SUPERIOR THIS AFTN (ESPECIALLY LATE)
AND TONIGHT FROM THE MN ARROWHEAD TO GOGEBIC/ONTONAGON COUNTIES. THE
RESULTING SHARP CONVERGENCE SHOULD REALLY AID LAKE ENHANCEMENT
POTENTIAL. WITH SNOW RATIOS OVERALL PROBABLY A LITTLE UNDER 20:1...
EVENT SHOULD EASILY EXCEED LOWER RATIO ADVY CRITERIA SNOWFALL (3
INCHES OR MORE IN 12HRS) WHERE LOW-LEVEL CONVERGENCE IS MAXIMIZED...
PROBABLY IN A FAIRLY SMALL AREA FROM KIWD TO WAKEFIELD...BERGLAND
AND WHITE PINE. PLAN TO RUN ADVY FOR ONTONAGON/GOGEBIC FROM 21Z
TODAY TO 15Z SAT FOR TOTAL SNOW ACCUMULATION OF 5-9 INCHES. EMPHASIS
WILL BE ON THE AREA MENTIONED. WITH SOME LES ALEADY NOTED OVER WRN
LAKE SUPERIOR ON KDLH RADAR AND A DECENT BAND OF SYNOPTIC SNOW
ASSOCIATED WITH APPROACHING SFC TROF...IT`S NOT OUT OF THE QUESTION
THAT SNOWFALL COULD BECOME QUITE A BIT HEAVIER THAN CURRENTLY
ANTICIPATED. WILL NEED TO WATCH MORNING/AFTN TRENDS FOR POTENTIAL
UPGRADE TO WARNING. ELSEWHERE ALONG LAKE SUPERIOR...SLIGHT COOLING
OF AIR MASS AND STRENGTHENING NORTHERLY WINDS WILL LEAD TO AN
INCREASE IN LES THIS AFTN INTO TONIGHT. ACCUMULATIONS WILL BE
LIGHTER THAN OVER THE FAR W DUE TO LESS INFLUENCE FROM SHORTWAVE...
SHALLOWER MOISTURE AND WEAKER LOW-LEVEL CONVERGENCE. WITH LONGER
FETCH AND MORE FAVORABLE WIND DIRECTION...SOME LOCATIONS FROM ERN
MARQUETTE COUNTY INTO ALGER COUNTY MAY SEE A FEW INCHES OF SNOW THRU
SAT MORNING.
DRIER AIR...LOWERING INVERSION AND INCREASINGLY ANTICYCLONIC FLOW AS
WINDS BACK WILL LEAD TO DIMINISHING LES SAT. WITH 850MB TEMPS AROUND
-14C...PROBABLY WON`T SEE LES COMPLETELY END SAT AFTN.
ANY LINGERING LES/FLURRIES WILL END SAT EVENING AS SFC HIGH PRES
RIDGE SHIFTS ACROSS THE AREA. MIGHT BE A WINDOW FOR TEMPS TO PLUMMET
BEFORE HIGH CLOUDS INCREASE/THICKEN FROM W TO E DURING THE NIGHT.
BEST OPPORTUNITY WOULD PROBABLY BE OVER THE CNTRL DUE TO LONGER
PERIOD BTWN DEPARTURE OF LAKE STRATOCU AND INCREASE OF HIGH CLOUDS.
.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 521 AM EST FRI FEB 24 2012
A 500MB SHORTWAVE TROUGH CURRENTLY OVER THE PACIFIC NW CONUS WILL
HAVE MOVED INTO THE NRN PLAINS BY THE START OF THE PERIOD 12Z
SUN...SPINNING UP A SFC LOW AS IT MOVED LEEWARD OF THE ROCKIES. THE
SFC LOW IS DEPICTED BY MODELS TO BE OVER ERN SD AT 12Z SUN. MODELS
STILL VARY IN THE INTENSITY OF THE SYSTEM AT THIS POINT...AND
THROUGH THE TIME THE SYSTEM PASSES OVER THE CWA. THE 12Z/23 ECMWF
AND 00Z/24 GEM ARE ON THE STRONGER SIDE OF GUIDANCE WITH THE SFC LOW
AROUND 996MB AT 12Z SUN...WHILE THE 00Z/24 GFS AND 00Z/24 NAM SHOW THE
SFC LOW AT 1002MB. ASSIDE FROM SYSTEM STRENGTH...MODELS ARE IN GOOD
AGREEMENT ON THE TRACK AND FAIR AGREEMENT ON THE SPEED OF THE
SYSTEM...WITH THE DEEPER ECMWF AND GEM BEING ON THE SLOW SIDE OF
GUIDANCE. USED A CONSENSUS OF THE MODELS FOR THE SPEED OF THE
SYSTEM...WHICH IS WEAKENING AS THE SHORTWAVE GETS SHEARED APART WITH
EASTWARD MOVEMENT.
WITH THAT IN MIND...THE SFC LOW /AND UPPER SHORTWAVE OVER OR JUST N
OF THE SFC LOW/ MOVES TO NEAR IRONWOOD BY 00Z MON. THE SFC LOW THEN
MOVES ACROSS UPPER MI...BEFORE MOVING TO THE FAR ERN CWA BY 12Z MON.
THIS TRACK CONFINES THE HEAVIEST SNOW /AND IT IS EXPECTED TO BE ALL
SNOW/ TO FAR NRN UPPER MI AND LAKE SUPERIOR. SYNOPTIC SNOW LOOKS TO
BE JUST MOVING INTO THE WRN CWA AROUND 12Z SUN...COVERING ROUGHLY
THE WRN HALF OF UPPER MI BY 18Z. THERE IS THE POSSIBILITY FOR SOME
LES OVER ERN UPPER MI IN THE ANTICYCLONIC FLOW AND 850MB TEMPS
AROUND -12C AHEAD OF THE SYSTEM...BUT WILL KEEP THAT AT CHANCE POPS
FOR NOW. IT THEN LOOKS LIKE A DRY SLOT WILL ROTATE IN...ESPECIALLY
OVER THE SRN CWA. THE GFS CRANKS OUT AROUND 0.4 INCHES OF QPF OVER
MUCH OF UPPER MI THROUGH 12Z MON...BEFORE THE SYSTEM MOVES OUT AND
LES STARTS. THE NAM SHOWS CLOSER TO 0.5 INCHES OVER MUCH OF THE
AREA. THE ECMWF SHOWS AROUND 0.4 INCHES OF QPF OVER THE KEWEENAW
PENINSULA AND LAKE SUPERIOR...WITH AROUND 0.2 INCHES OVER ALL BUT
SRN MENOMINEE COUNTY WHERE IT SHOWS LESS THAN 0.1 INCHES. THE GEM IS
VERY CLOSE TO THE GFS SOLUTION FOR QPF. THERE ARE SIGNALS THAT
INDICATE WE MAY GET A HEAVIER BAND OF SNOW ALONG THE WARM FRONT THAT
SURGES NORTHWARD LATE SUNDAY...WHICH WOULD FAVOR AREAS OF S CENTRAL
AND ERN UPPER MI TO GET SOME HEAVIER SNOW. WILL NOT PUT THIS DETAIL
INTO THE GRIDS JUST YET SINCE THERE IS STILL SOME UNCERTAINTY IN THE
TRACK/TIMING OF THE SYSTEM. AS FOR QPF AMOUNTS...THE GFS AND GEM
SOLUTIONS WERE GOOD COMPROMISES BETWEEN THE ECMWF AND GEM
OUTLIERS...SO I USED THOSE. THIS RESULTS IN AROUND 4 INCHES OF SNOW
STORM TOTAL.
ADDITIONAL SNOW WILL BE LIKELY BEHIND THE SYSTEM AS LES KICKS IN DUE
TO FALLING 850MB TEMPS IN GENERALLY NW WINDS BEHIND THE SYSTEM.
MODEL SOLUTIONS DIVERGE ON THIS POINT STARTING MONDAY EVENING. THE
GFS IS MUCH FASTER TO BRING A SFC RIDGE IN FROM THE W THAN THE ECMWF
AND GEM...THUS KILLING THE LES FASTER AS WINDS BECOME COMPLETELY
OFFSHORE BY 12Z TUE.
MODELS THEN BRING A STRONG LOW PRESSURE SYSTEM FROM THE CENTRAL
PLAINS TUESDAY TO SOMEWHERE S OF THE AREA WED. THERE HAS BEEN
CONSIDERABLE MODEL VARIABILITY WITH THE TRACK OF THIS SYSTEM. THIS
COMBINED WITH INCREASED ATTENTION TO THE SUN/MON STORM LEAD ME TO
USE A CONSENSUS OF MODEL GUIDANCE FOR THE TUE THROUGH THU PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 628 AM EST FRI FEB 24 2012
INCREASING NRLY FLOW/COOLER AIR WILL BRING LAKE EFFECT SNOW TO
KIWD/KCMX/KSAW DURING THIS FCST PERIOD. KIWD SHOULD BE MOST AFFECTED
AS APPROACHING MID LEVEL DISTURBANCE AND ASSOCIATED SFC TROF FOCUS
SNOW INTO FAR WRN UPPER MI. EXPECT VFR CONDITIONS TO START AT KIWD
TO DROP TO IFR AT TIMES IN THE NEXT FEW HRS AS WINDS SHIFT OFF THE
LAKE. CONDITIONS SHOULD THEN SETTLE TO MVFR BEFORE DROPPING TO
PREVAILING IFR LATER IN THE AFTN THRU TONIGHT AS TROF/CONVERGENT
FLOW SET UP ACROSS WRN LAKE SUPERIOR INTO FAR WRN UPPER MI. AT
KCMX...MVFR CONDITIONS SHOULD MOSTLY PREVAIL THOUGH SOME PERIODS OF
IFR ARE POSSIBLE. AT KSAW...INCREASINGLY NORTHERLY FLOW/UPSLOPE
WILL BRING LOWER MVFR CONDITIONS TODAY WITH -SHSN BECOMING MORE
FREQUENT. SOME PERIODS OF IFR ARE POSSIBLE. SLIGHT BACKING OF WINDS
TONIGHT SHOULD RESULT IN IMPROVING VIS AS MORE PERSISTENT/HEAVIER
SNOW SHOWERS SHIFT E.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 521 AM EST FRI FEB 24 2012
ACTIVE WEATHER EXPECTED THRU THE MIDDLE OF NEXT WEEK WITH A
PROGRESSIVE REGIME BRINGING A SERIES OF LOW PRES AND HIGH PRES
SYSTEMS ACROSS THE GREAT LAKES REGION. DEEPENING LOW PRES HEADING
FROM THE OHIO VALLEY TO NEW ENGLAND WILL RESULT IN INCREASING
NORTHERLY WINDS TO 15-25KT TODAY AND TONIGHT. WINDS WILL DIMINISH
FROM W TO E SAT/SAT NIGHT AS HIGH PRES RIDGE ARRIVES. ALREADY BY
LATE SAT NIGHT WINDS WILL BE ON THE INCREASE AGAIN OVER WRN LAKE
SUPERIOR IN RESPONSE TO THE NEXT LOW PRES SYSTEM MOVING OUT OVER THE
NRN PLAINS. WINDS SHOULD INCREASE UP TO 30KT SUN AS THE LOW
APPROACHES. WITH THE LOW WEAKENING AS IT PASSES...WINDS ON THE
BACKSIDE OF THE SYSTEM MON WON`T BE AS STRONG...15-25KT SUN NIGHT
INTO EARLY MON. WINDS WILL CONTINUE TO DIMINISH INTO TUE AS HIGH
PRES ARRIVES. WINDS WILL BE ON THE INCREASE AGAIN WED AS THE NEXT
LOW PRES SYSTEM APPROACHES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY FROM 4 PM EST /3 PM CST/ THIS AFTERNOON
TO 11 AM EST /10 AM CST/ SATURDAY FOR MIZ002-009.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...TITUS
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
523 AM EST FRI FEB 24 2012
.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 521 AM EST FRI FEB 24 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A TROF OVER THE CNTRL
CONUS. A VIGOROUS LOOKING SHORTWAVE TRACKING E INTO IL WAS
SUPPORTING A BAND OF SNOW FROM ERN IA ACROSS SRN WI/NRN IL INTO LWR
MI. UPSTREAM....A SHORTWAVE TROF EXTENDS FROM SRN MANITOBA THRU THE
ERN DAKOTAS/WRN MN WITH VORT MAX APPARENT OVER SE MANITOBA. AT THE
SFC...OBS INDICATE ASSOCIATED WEAK SFC LOW N OF KINL WITH TROF
EXTENDING SE TOWARD WRN LAKE SUPERIOR...AND KDLH RADAR SHOWS A BAND
OF -SN ALONG THE TROF. CLOSER TO HOME...MOISTURE EXTENDING TO AROUND
6KFT PER FCST SOUNDINGS AND IMPLIED BY KMQT VAD WIND PROFILE ALONG
WITH 850MB TEMPS OF -9/-10C IS SUPPORTING FLURRIES/-SHSN OFF LAKE
SUPERIOR INTO NCNTRL UPPER MI. -SHSN TRENDS OVERNIGHT HAVE BEEN ODD
WITH UNORGANIZED SNOW AREAS DEVELOPING AND INTENSIFYING OVER THE
WATER ONLY TO PERSIST FOR A WHILE AND THEN RAPIDLY WEAKEN. SHORT
TERM FCST CONCERNS WILL REVOLVE AROUND SHORTWAVE TO THE NW...AND THE
AFFECTS IT WILL HAVE ON LAKE EFFECT LATER TODAY THRU TONIGHT.
00Z CWPL SOUNDING PROBABLY GIVES A DECENT REPRESENTATION OF AIR MASS
THAT WILL BE OVER THE WRN FCST AREA LATER TODAY/TONIGHT. IF SO...
850MB TEMPS WILL DROP A COUPLE OF DEGREES C AND COLUMN MOISTURE WILL
DEEPEN SIGNIFICANTLY. MODEL GUIDANCE IS IN GOOD AGREEMENT ON THIS
COOLING/MOISTENING. AT THE SAME...TIME WEAK DEEP LAYER FORCING WILL
OVERSPREAD WRN LAKE SUPERIOR/WRN UPPER MI IN ASSOCIATION WITH
AFOREMENTIONED SHORTWAVE TO THE NW. AT THE LOW LEVELS...THERE IS
GOOD AGREEMENT AMONG NUMEROUS MODELS THAT APPROACHING SFC TROF WILL
BASICALLY HANG UP OVER WRN LAKE SUPERIOR THIS AFTN (ESPECIALLY LATE)
AND TONIGHT FROM THE MN ARROWHEAD TO GOGEBIC/ONTONAGON COUNTIES. THE
RESULTING SHARP CONVERGENCE SHOULD REALLY AID LAKE ENHANCEMENT
POTENTIAL. WITH SNOW RATIOS OVERALL PROBABLY A LITTLE UNDER 20:1...
EVENT SHOULD EASILY EXCEED LOWER RATIO ADVY CRITERIA SNOWFALL (3
INCHES OR MORE IN 12HRS) WHERE LOW-LEVEL CONVERGENCE IS MAXIMIZED...
PROBABLY IN A FAIRLY SMALL AREA FROM KIWD TO WAKEFIELD...BERGLAND
AND WHITE PINE. PLAN TO RUN ADVY FOR ONTONAGON/GOGEBIC FROM 21Z
TODAY TO 15Z SAT FOR TOTAL SNOW ACCUMULATION OF 5-9 INCHES. EMPHASIS
WILL BE ON THE AREA MENTIONED. WITH SOME LES ALEADY NOTED OVER WRN
LAKE SUPERIOR ON KDLH RADAR AND A DECENT BAND OF SYNOPTIC SNOW
ASSOCIATED WITH APPROACHING SFC TROF...IT`S NOT OUT OF THE QUESTION
THAT SNOWFALL COULD BECOME QUITE A BIT HEAVIER THAN CURRENTLY
ANTICIPATED. WILL NEED TO WATCH MORNING/AFTN TRENDS FOR POTENTIAL
UPGRADE TO WARNING. ELSEWHERE ALONG LAKE SUPERIOR...SLIGHT COOLING
OF AIR MASS AND STRENGTHENING NORTHERLY WINDS WILL LEAD TO AN
INCREASE IN LES THIS AFTN INTO TONIGHT. ACCUMULATIONS WILL BE
LIGHTER THAN OVER THE FAR W DUE TO LESS INFLUENCE FROM SHORTWAVE...
SHALLOWER MOISTURE AND WEAKER LOW-LEVEL CONVERGENCE. WITH LONGER
FETCH AND MORE FAVORABLE WIND DIRECTION...SOME LOCATIONS FROM ERN
MARQUETTE COUNTY INTO ALGER COUNTY MAY SEE A FEW INCHES OF SNOW THRU
SAT MORNING.
DRIER AIR...LOWERING INVERSION AND INCREASINGLY ANTICYCLONIC FLOW AS
WINDS BACK WILL LEAD TO DIMINISHING LES SAT. WITH 850MB TEMPS AROUND
-14C...PROBABLY WON`T SEE LES COMPLETELY END SAT AFTN.
ANY LINGERING LES/FLURRIES WILL END SAT EVENING AS SFC HIGH PRES
RIDGE SHIFTS ACROSS THE AREA. MIGHT BE A WINDOW FOR TEMPS TO PLUMMET
BEFORE HIGH CLOUDS INCREASE/THICKEN FROM W TO E DURING THE NIGHT.
BEST OPPORTUNITY WOULD PROBABLY BE OVER THE CNTRL DUE TO LONGER
PERIOD BTWN DEPARTURE OF LAKE STRATOCU AND INCREASE OF HIGH CLOUDS.
.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 521 AM EST FRI FEB 24 2012
A 500MB SHORTWAVE TROUGH CURRENTLY OVER THE PACIFIC NW CONUS WILL
HAVE MOVED INTO THE NRN PLAINS BY THE START OF THE PERIOD 12Z
SUN...SPINNING UP A SFC LOW AS IT MOVED LEEWARD OF THE ROCKIES. THE
SFC LOW IS DEPICTED BY MODELS TO BE OVER ERN SD AT 12Z SUN. MODELS
STILL VARY IN THE INTENSITY OF THE SYSTEM AT THIS POINT...AND
THROUGH THE TIME THE SYSTEM PASSES OVER THE CWA. THE 12Z/23 ECMWF
AND 00Z/24 GEM ARE ON THE STRONGER SIDE OF GUIDANCE WITH THE SFC LOW
AROUND 996MB AT 12Z SUN...WHILE THE 00Z/24 GFS AND 00Z/24 NAM SHOW THE
SFC LOW AT 1002MB. ASSIDE FROM SYSTEM STRENGTH...MODELS ARE IN GOOD
AGREEMENT ON THE TRACK AND FAIR AGREEMENT ON THE SPEED OF THE
SYSTEM...WITH THE DEEPER ECMWF AND GEM BEING ON THE SLOW SIDE OF
GUIDANCE. USED A CONSENSUS OF THE MODELS FOR THE SPEED OF THE
SYSTEM...WHICH IS WEAKENING AS THE SHORTWAVE GETS SHEARED APART WITH
EASTWARD MOVEMENT.
WITH THAT IN MIND...THE SFC LOW /AND UPPER SHORTWAVE OVER OR JUST N
OF THE SFC LOW/ MOVES TO NEAR IRONWOOD BY 00Z MON. THE SFC LOW THEN
MOVES ACROSS UPPER MI...BEFORE MOVING TO THE FAR ERN CWA BY 12Z MON.
THIS TRACK CONFINES THE HEAVIEST SNOW /AND IT IS EXPECTED TO BE ALL
SNOW/ TO FAR NRN UPPER MI AND LAKE SUPERIOR. SYNOPTIC SNOW LOOKS TO
BE JUST MOVING INTO THE WRN CWA AROUND 12Z SUN...COVERING ROUGHLY
THE WRN HALF OF UPPER MI BY 18Z. THERE IS THE POSSIBILITY FOR SOME
LES OVER ERN UPPER MI IN THE ANTICYCLONIC FLOW AND 850MB TEMPS
AROUND -12C AHEAD OF THE SYSTEM...BUT WILL KEEP THAT AT CHANCE POPS
FOR NOW. IT THEN LOOKS LIKE A DRY SLOT WILL ROTATE IN...ESPECIALLY
OVER THE SRN CWA. THE GFS CRANKS OUT AROUND 0.4 INCHES OF QPF OVER
MUCH OF UPPER MI THROUGH 12Z MON...BEFORE THE SYSTEM MOVES OUT AND
LES STARTS. THE NAM SHOWS CLOSER TO 0.5 INCHES OVER MUCH OF THE
AREA. THE ECMWF SHOWS AROUND 0.4 INCHES OF QPF OVER THE KEWEENAW
PENINSULA AND LAKE SUPERIOR...WITH AROUND 0.2 INCHES OVER ALL BUT
SRN MENOMINEE COUNTY WHERE IT SHOWS LESS THAN 0.1 INCHES. THE GEM IS
VERY CLOSE TO THE GFS SOLUTION FOR QPF. THERE ARE SIGNALS THAT
INDICATE WE MAY GET A HEAVIER BAND OF SNOW ALONG THE WARM FRONT THAT
SURGES NORTHWARD LATE SUNDAY...WHICH WOULD FAVOR AREAS OF S CENTRAL
AND ERN UPPER MI TO GET SOME HEAVIER SNOW. WILL NOT PUT THIS DETAIL
INTO THE GRIDS JUST YET SINCE THERE IS STILL SOME UNCERTAINTY IN THE
TRACK/TIMING OF THE SYSTEM. AS FOR QPF AMOUNTS...THE GFS AND GEM
SOLUTIONS WERE GOOD COMPROMISES BETWEEN THE ECMWF AND GEM
OUTLIERS...SO I USED THOSE. THIS RESULTS IN AROUND 4 INCHES OF SNOW
STORM TOTAL.
ADDITIONAL SNOW WILL BE LIKELY BEHIND THE SYSTEM AS LES KICKS IN DUE
TO FALLING 850MB TEMPS IN GENERALLY NW WINDS BEHIND THE SYSTEM.
MODEL SOLUTIONS DIVERGE ON THIS POINT STARTING MONDAY EVENING. THE
GFS IS MUCH FASTER TO BRING A SFC RIDGE IN FROM THE W THAN THE ECMWF
AND GEM...THUS KILLING THE LES FASTER AS WINDS BECOME COMPLETELY
OFFSHORE BY 12Z TUE.
MODELS THEN BRING A STRONG LOW PRESSURE SYSTEM FROM THE CENTRAL
PLAINS TUESDAY TO SOMEWHERE S OF THE AREA WED. THERE HAS BEEN
CONSIDERABLE MODEL VARIABILITY WITH THE TRACK OF THIS SYSTEM. THIS
COMBINED WITH INCREASED ATTENTION TO THE SUN/MON STORM LEAD ME TO
USE A CONSENSUS OF MODEL GUIDANCE FOR THE TUE THROUGH THU PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1220 AM EST FRI FEB 24 2012
LIGHT NORTHERLY CONVERGENT WINDS MAY RESULT IN OCCASIONAL IFR
CONDITIONS IN LIGHT LAKE EFFECT SNOW AT KSAW THROUGH 10Z...ALTHOUGH
SNOW SHOULD DIMINISH TO FLURRIES THEREAFTER. A LIGHT NRLY FLOW AND
MARGINAL OVER-WATER INSTABILITY SHOULD CONTINUE MVFR CONDITIONS AT
KSAW AND KCMX THROUGH MUCH OF TONIGHT INTO FRIDAY EVENING. AT
KIWD...MVFR CONDITIONS ARE EXPECTED TO GIVE WAY TO IFR CONDITIONS BY
LATE FRIDAY AFTERNOON AS LOW-LVL CONVERGENCE INCREASES AND
ENHANCEMENT OF LAKE EFFECT SNOW IS POSSIBLE FROM UPPER DISTURBANCE
MOVING ACROSS THE AREA.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 521 AM EST FRI FEB 24 2012
ACTIVE WEATHER EXPECTED THRU THE MIDDLE OF NEXT WEEK WITH A
PROGRESSIVE REGIME BRINGING A SERIES OF LOW PRES AND HIGH PRES
SYSTEMS ACROSS THE GREAT LAKES REGION. DEEPENING LOW PRES HEADING
FROM THE OHIO VALLEY TO NEW ENGLAND WILL RESULT IN INCREASING
NORTHERLY WINDS TO 15-25KT TODAY AND TONIGHT. WINDS WILL DIMINISH
FROM W TO E SAT/SAT NIGHT AS HIGH PRES RIDGE ARRIVES. ALREADY BY
LATE SAT NIGHT WINDS WILL BE ON THE INCREASE AGAIN OVER WRN LAKE
SUPERIOR IN RESPONSE TO THE NEXT LOW PRES SYSTEM MOVING OUT OVER THE
NRN PLAINS. WINDS SHOULD INCREASE UP TO 30KT SUN AS THE LOW
APPROACHES. WITH THE LOW WEAKENING AS IT PASSES...WINDS ON THE
BACKSIDE OF THE SYSTEM MON WON`T BE AS STRONG...15-25KT SUN NIGHT
INTO EARLY MON. WINDS WILL CONTINUE TO DIMINISH INTO TUE AS HIGH
PRES ARRIVES. WINDS WILL BE ON THE INCREASE AGAIN WED AS THE NEXT
LOW PRES SYSTEM APPROACHES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY FROM 4 PM EST /3 PM CST/ THIS AFTERNOON
TO 11 AM EST /10 AM CST/ SATURDAY FOR MIZ002-009.
LAKE SUPERIOR...NONE.
LAKE MICHIGAN...NONE.
&&
$$
SHORT TERM...ROLFSON
LONG TERM...TITUS
AVIATION...VOSS
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
547 AM CST FRI FEB 24 2012
.AVIATION...
MAINLY VFR CONDITIONS THIS MORNING ACROSS THE AREA. A DISTURBANCE
WILL BRING A SLIGHT CHANCE FOR LIGHT SNOW SHOWERS ACROSS NORTHERN
INTO CENTRAL NEBRASKA THIS MORNING AND EARLY AFTERNOON. THE
ISOLATED SNOW SHOWERS WILL BRING POCKETS OF MVFR CIGS...AT OR
ABOVE BKN025...THROUGH LATE AFTERNOON. IMPACT OF MVFR IS EXPECTED
TO REMAIN ALONG AND EAST OF A KIEN TO KBBW LINE. WIDESPREAD VFR
EXPECTED AFTER 00Z AS SYSTEM PUSHES SOUTHEAST OF THE AREA.
WEST/NORTHWEST WINDS WILL BE INCREASING LATER THIS MORNING...WITH
GUSTS ABOVE 25 KTS THIS AFTERNOON. AFTER SUNSET...WINDS SHOULD
QUICKLY DIMINISH.
&&
.PREV DISCUSSION... /ISSUED 352 AM CST FRI FEB 24 2012/
SHORT TERM...TODAY THROUGH SUNDAY NIGHT
FAIRLY ACTIVE PATTERN THROUGH THE NEXT WEEK WITH THE SHORT TERM
FOCUS ON FRIDAY WITH A WEAK SHORTWAVE TROUGH MOVING ACROSS THE
AREA WITH CHANCES FOR SNOW SHOWERS AND WINDY CONDITIONS AGAIN. A
BRIEF WARM UP IS EXPECTED FOR SATURDAY...ALONG WITH WINDY
SOUTHERLY WINDS...THEN FOCUS TURNS TO PRECIPITATION CHANCES AND
WINDS AGAIN ON SUNDAY AND SUNDAY NIGHT AS THE NEXT SYSTEM MOVES
ACROSS THE AREA.
AT 08Z WATER VAPOR SHOWED THE TROUGH THAT BROUGHT THE STRONG WINDS
TO THE AREA YESTERDAY HAD PUSHED INTO MISSOURI AND ILLINOIS WITH
RIDGING CONTINUING OVER THE WESTERN CONUS...KEEPING THE LOCAL AREA
UNDER NORTHWEST FLOW. LOOKING UPSTREAM...IS SOME DARKENING IN THE
WATER VAPOR OVER ALBERTA WHICH IS CONFIRMED BY LOWERED PRESSURE ON
THE 1.5PV SURFACE BY THE RUC ANALYSIS. FURTHER UPSTREAM...A ROBUST
SHORTWAVE TROUGH WAS MAKING ITS WAY ACROSS THE NORTHERN PACIFIC.
AT THE SURFACE...THE SURFACE LOW HAD MOVED EAST AND WAS OVER
ILLINOIS...WITH HIGH PRESSURE OVER COLORADO. WINDS HAD SUBSIDED
OVERNIGHT AS THE PRESSURE GRADIENT RELAXED. LAPS RATES REMAINED
QUITE STEEP AS INDICATED BY LAPS SOUNDINGS ACROSS THE FORECAST
AREA WHICH HAS HELPED TO CONTINUE SOME SCATTERED SHOWERS MOVING
SOUTHEAST ACROSS THE CENTRAL PART OF THE FORECAST AREA.
OBSERVATIONS ARE INDICATING CEILINGS MAINLY AT 5K FEET AND RADAR
ECHOES ARE QUITE LIGHT AND NOT STABLE SO DON/T THINK THERE IS
MUCH/IF ANYTHING REACHING THE SURFACE.
FOR TODAY...ALTHOUGH THERE WILL BE WARM AIR ADVECTION ALOFT /ABOVE
600MB AS RIDGING SLOWLY BUILDS IN...LAPS RATES BELOW 600MB WILL
REMAIN STEEP /7-8 DEGREES PER KM/ AND AS THE SHORTWAVE OVER
ALBERTA MOVES SOUTHEAST BRINGING SOME EXTRA LIFT ACROSS THE AREA
LATER THIS MORNING AND THIS AFTERNOON...EXPECTING ISOLATED TO
SCATTERED SNOW SHOWERS MAINLY EAST OF A PINE RIDGE TO NORTH PLATTE
LINE. THERE ISN/T MUCH MOISTURE TO WORK WITH SO DON/T EXPECT
MUCH/IF ANY FOR ACCUMULATIONS. OTHER CONCERN FOR TODAY IS WINDS.
ALTHOUGH THE PRESSURE GRADIENT WON/T YIELD STRONG WINDS...THE
STEEP LAPSE RATES /GOOD MIXING/ WILL LIKELY BRING ABOUT SOME WINDY
CONDITIONS. BUFKIT FORECAST SOUNDINGS FROM THE NAM INDICATE WINDS
AT THE TOP OF THE MIXED LAYER THIS AFTERNOON OF 35 TO 45KTS. WHILE
THE GFS IS A BIT HIGHER...UP TO 50KTS AT 700MB. AS THIS ISN/T A
STRONG COLD AIR ADVECTION/SUBSIDENT REGIME...EVEN THOUGH HAVE THE
STRONG LAPSE RATES...DON/T KNOW IF THOSE WINDS WILL BE ABLE TO BE
MIXED TO THE SURFACE. DID INCREASE WINDS IN THE FORECAST...AND MAY
HAVE A FEW POINTS THAT REACH ADVISORY CRITERIA...BUT WITH
CONFIDENCE LESS THAN 50 PERCENT AND IT BEING LOW END AND NOT
WIDESPREAD OPTED TO NOT ISSUE ANY HEADLINES FOR TODAY. DAYSHIFT
CAN MONITOR IF THE WINDS INCREASE TOO MUCH AND IF AN ADVISORY WOULD
BE NEEDED.
THE TROUGH OVER THE NORTHERN PACIFIC WILL PUSH OVER THE RIDGE
TONIGHT AND SATURDAY...WITH LOW PRESSURE DEVELOPING AT THE SURFACE
ON THE LEE SIDE OF THE ROCKIES OVER MONTANA/WYOMING AND COLORADO.
THIS WILL BRING A BRIEF WINDOW OF RIDGING ACROSS THE PLAINS...WITH
WARMER TEMPERATURES EXPECTED FOR SATURDAY. THERE LOOKS TO BE
PLENTY OF SUNSHINE...BUT WITH JUST A QUICK WINDOW FOR WARMING ONLY
HAVE FORECAST HIGHS IN THE 40S TO MID 50S IN THE SOUTH. SOUTHERLY
WINDS WILL ALSO BE PRETTY BREEZY ON SATURDAY AS THE LOW PRESSURE
TO THE WEST STRENGTHENS. CURRENTLY LOOKS LIKE WINDS WILL STAY
BELOW ADVISORY CRITERIA.
THE UPPER LEVEL LOW WILL TRACK NORTH OF THE AREA /OVER THE
DAKOTAS/ AS WILL THE SURFACE LOW. THE COLD FRONT WILL PASS THE
FORECAST AREA SATURDAY NIGHT...BRINGING A WIND SHIFT...BUT LITTLE
IF ANY PRECIPITATION TO ALL BUT THE NORTHERN TIER OF COUNTIES.
DEEP MOISTURE WILL FOR THE MOST PART STAY NORTH OF THE AREA SO
WILL JUST CONTINUE THE SLIGHT CHANCES FOR SNOW OVER THE NORTHERN
COUNTIES. AGAIN...WINDY CONDITIONS ARE EXPECTED BEHIND THE COLD
FRONT WITH A FAIRLY TIGHT PRESSURE GRADIENT ACROSS SOUTH DAKOTA
AND INTO NEBRASKA THROUGH SUNDAY. STRONGEST WINDS LOOK TO BE NORTH
OF THE HIGHWAYS 2 AND 91 CORRIDOR.
LONG TERM...MONDAY THROUGH THURSDAY
THIS PERIOD ALSO LOOKS FAIRLY ACTIVE WITH A STRONG SYSTEM
PROJECTED TO MOVE ACROSS THE CENTRAL PLAINS MONDAY NIGHT THROUGH
WEDNESDAY. THE UPPER LEVEL SYSTEM WILL MOVE ONSHORE ON
MONDAY...THEN TRACK TOWARDS THE CENTRAL PLAINS MONDAY NIGHT. THE
TRACK OF THIS SYSTEM HAS TRENDED NORTH...WHICH BRINGS WARMER AIR
INTO PLAY WHICH COULD CAUSE ISSUES WITH PRECIPITATION TYPE. THE
LOW LEVEL FLOW WOULD SUGGEST A WIDE OPEN GULF WITH STRONG MOISTURE
TRANSPORT NORTHWARD. ALSO...LOOKING AT THE ISENTROPIC
SURFACES...STRONG LIFT ALONG WITH SPECIFIC HUMIDITIES OF 5 TO 6
G/KG INTO SOUTHWEST NEBRASKA INDICATE PLENTY OF JUICE FOR
PRECIPITATION. THE SURFACE LOW DEEPENS OVER EASTERN COLORADO AND A
WARM FRONT PUSHES NORTH INTO NEBRASKA MONDAY NIGHT. THE MODEL
SOLUTIONS HAVE COME INTO DECENT AGREEMENT WITH BRINGING THE WARM
AIR INTO MUCH OF THE FORECAST AREA...WHICH COULD BE WARM ENOUGH
FOR A RAIN/SNOW MIX OR JUST RAIN ACROSS SOUTHERN INTO NORTHEAST
NEBRASKA MONDAY NIGHT INTO TUESDAY. DID RAISE LOW TEMPERATURES A
BIT BUT DUE TO THE LIKELIHOOD THAT THERE WILL BE CHANGES YET AS
THE SYSTEM GETS CLOSER...DIDN/T GO TOO WARM. THE GFS IS THE
WARMEST SOLUTION WHICH WOULD SUGGEST RAIN OVER THE ENTIRE FORECAST
AREA MONDAY NIGHT INTO TUESDAY. AT THIS POINT WANT TO EXERCISE
SOME CAUTION SO JUST WENT WITH A RAIN/SNOW MIX OVER THE
SOUTHEASTERN HALF WITH SNOW OVER THE PANHANDLE AND NORTHWEST
NEBRASKA. AS THE LOW MOVES EAST...ARCTIC AIR WILL COME SOUTH ON
THE BACK SIDE OF THE SYSTEM WHICH WILL SWITCH PRECIPITATION OVER
TO ALL SNOW BY THE END OF THE DAY TUESDAY. SOMETHING ELSE TO
CONSIDER AS THERE IS COLDER AIR TO DEAL WITH...ALONG WITH A GOOD
TONGUE OF WARM AIR ABOVE THE SURFACE IS IF THERE WILL BE AN AREA
OF FREEZING RAIN OR SLEET. AS WAS STATED EARLIER...STILL NOT A
GREAT DEAL OF CONFIDENCE IN HOW THIS WILL ALL PLAY OUT SO DIDN/T
WANT TO ADD THE FREEZING PRECIPITATION TYPES INTO THE FORECAST
QUITE YET. SOMETHING TO KEEP IN MIND THOUGH.
SHOULD GET A SMALL BREAK WEDNESDAY AND WEDNESDAY NIGHT BEFORE THE
NEXT SYSTEM CROSSES THE ROCKIES ON THURSDAY...SO HAVE CHANCES FOR
PRECIPITATION AGAIN FOR THURSDAY NIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT/LONG TERM...BROOKS
AVIATION...MASEK
AREA FORECAST DISCUSSION
NWS BUFFALO NY
708 AM EST FRI FEB 24 2012
.SYNOPSIS...
LOW PRESSURE WILL INTENSIFY AS IT TRACKS ACROSS THE EASTERN GREAT LAKES
THROUGH THIS EVENING. THIS WILL BRING SOME SNOW AND RAIN TO THE
REGION TODAY...FOLLOWED BY WINDY CONDITIONS AND SOME LAKE EFFECT SNOW
TONIGHT. THE LOW WILL TRACK INTO THE MARITIMES SATURDAY...WITH
MORE LAKE SNOWS IN SOME LOCATIONS.
&&
.NEAR TERM /THROUGH TONIGHT/...
A VERY ACTIVE PATTERN WITH LOTS TO TALK ABOUT HERE. MODELS HAVE
FINALLY COME INTO GOOD AGREEMENT IN HANDLING THIS SYSTEM. A FAIRLY
TIGHT CONSENSUS TRACKS THE SURFACE LOW ACROSS LAKE ERIE LATE THIS
AFTERNOON AND ACROSS LAKE ONTARIO THIS EVENING. AT THIS TIME...THE
LOW WILL BE DEEPENING RAPIDLY...AS IT IS CLOSING OFF IN THE UPPER
LEVELS.
THROUGH THIS MORNING...A BAND OF WARM AIR ADVECTION ALOFT EXTENDS
TO THE EAST OF THE DEVELOPING LOW. THIS BAND WILL CONTINUE TO
WEAKEN AS IT LIFTS NORTHWARD...PERHAPS BRINGING AN INCH OR SO OF
SNOW BEFORE IT TAPERS OFF AND CHANGES TO RAIN. OTHERWISE...EXPECT
SCATTERED RAIN SHOWERS SOUTH OF THIS...WITH TEMPERATURES WARMING
AS WINDS SHIFT TO THE SOUTHEAST. LATER THIS MORNING AND INTO THIS
AFTERNOON...TEMPERATURES SHOULD RISE INTO THE UPPER 40S AND LOWER
50S SOUTH OF THE THRUWAY AS WARMER AIR ADVECTS INTO THE REGION.
THEN EXPECT ANOTHER ROUND OF STEADIER PRECIPITATION TO MOVE IN
THIS AFTERNOON AS THE SURFACE LOW GETS CLOSER. FOR MOST...THIS
SHOULD BE RAIN...EXCEPT ACROSS JEFFERSON/LEWIS COUNTIES WHERE SNOW
AND SLEET STILL MAY MIX IN AT TIMES.
THERE WILL BE SEVERAL AREAS OF CONCERN STEM FROM THIS SYSTEM.
STRONG WINDS...
WINDS WILL SHIFT TO THE SOUTHWEST LATE THIS AFTERNOON...THEN TO
THE WEST THIS EVENING...AS THE LOW LIFTS ACROSS THE LAKES.
BECAUSE THE LOW IS DEEPENING RAPIDLY AT THIS TIME AS IT CLOSES OFF
AT 500 MB...EXPECT WINDS TO BE QUITE GUSTY THIS EVENING. A LOOK AT
FORECAST SOUNDINGS FOR THE 00Z/06Z NAM AND THE 09Z RUC ALL NOW
SHOWING 925 MB WINDS OF 50 TO 60 KTS ACROSS MUCH OF WESTERN NEW
YORK THIS EVENING. HAVE HIGH CONFIDENCE THAT GUSTY WINDS WILL MIX
DOWN ACROSS THE NIAGARA FRONTIER...WITH GUSTS TO 50 MPH LIKELY
THIS EVENING AS THE CHAUTAUQUA RIDGE AND LAKE INSTABILITY AID IN
MIXING. IN ADDITION...OPTED TO EXPAND THE WIND ADVISORY TO INCLUDE
MOST OF WESTERN NEW YORK AS STRONG WINDS ARE ALSO LIKELY TO MIX
DOWN ACROSS HIGHER TERRAIN. THIS IS SUPPORTED BY BUFKIT SOUNDINGS
AT WELLSVILLE...AND MATCHES UP WITH NEIGHBORING HEADLINES.
SNOW OFF LAKE ONTARIO (AND SYNOPTIC SNOW)...
IN ADDITION TO THE WINDS...COLDER AIR WILL BUILD IN BEHIND THE LOW.
WHILE 850 MB TEMPERATURES WILL ONLY DROP TO THE -6C TO -9C RANGE
OVERNIGHT...THERE WILL BE A LOT OF SYNOPTIC MOISTURE ON THE BACK OF
THE EXITING LOW. MODELS REFLECT THIS IN QPF FIELDS...WHICH APPEAR TO
KEY HEAVILY ON UPSLOPE FEATURES. IF IT WERE DRY IN THE BOUNDARY
LAYER...WOULD BE SKEPTICAL OF THESE QPF AMOUNTS...BUT GIVEN THE
CLOSE PROXIMITY OF THE MOISTURE WRAPPED LOW...GENERALLY ACCEPT QPF
FOR HIGHER RESOLUTION NAM12/RGEM. SNOW AMOUNTS WILL VARY...WITH THE
GREATEST AMOUNTS LIKELY EAST OF LAKE ONTARIO. HERE...TEMPERATURES
WILL BE COLDEST...AND UPSLOPING THE GREATEST. BECAUSE OF THIS...ISSUE
WARNINGS FOR THIS AREA...WITH THE TUG HILL LIKELY TO SEE ROUGHLY
FOOT OF SNOW FROM THIS. IN JEFFERSON/LEWIS COUNTIES...SNOWS WILL BE
MAINLY SYNOPTIC TODAY...AND LAKE ENHANCED TONIGHT...WHILE OSWEGO
COUNTY WILL SEE MORE OF A PURE LAKE EFFECT EVENT. WHILE HEADLINES
DIFFER SLIGHTLY...AM GENERALLY LOOKING FOR 6 O 12 INCHES IN THE
WARNING AREA...WITH A SLIGHTLY LATER START TIME FOR OSWEGO COUNTY.
THE BIGGEST IMPACT SHOULD BE ON THE TUG HILL TONIGHT...WHEN
UPSLOPE SNOWS COMBINE WITH GUSTY WINDS...WHICH WILL LIKELY PRODUCE
VERY POOR DRIVING CONDITIONS. EXPECT LESSER AMOUNTS SOUTHEAST OF
LAKE ONTARIO IN NORTHERN CAYUGA AND WAYNE COUNTIES. MOST ORGANIZED
BANDS WILL START LATE TONIGHT AND CONTINUE INTO SATURDAY.
SNOWS OFF LAKE ERIE...
OFF LAKE ERIE...SNOW AMOUNTS SHOULD BE LESS...BUT STILL SIGNIFICANT.
GENERALLY LOOKING FOR 4 TO 7 INCHES OF SNOW TONIGHT INTO SATURDAY IN
WESTERN PORTIONS OF THE SOUTHERN TIER. UPSLOPE REGIONS SHOULD
AGAIN SEE THE MOST SNOW...PARTICULARLY THE CHAUTAUQUA RIDGE AND
PERHAPS THE BOSTON HILLS. THIS HAS ALSO PROMPTED A LAKE EFFECT
ADVISORY.
FOR THE BIG CITIES OF BUFFALO AND ROCHESTER...EXPECT LESSER SNOW
AMOUNTS. WILL HAVE TO WATCH FOR POSSIBLE TIE INS WITH MOISTURE
UPSTREAM...AS THIS MAY LOCALLY ENHANCE SNOW FALL AMOUNTS.
OTHERWISE...EXPECTING AN INCH OR TWO TONIGHT.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
THE DEEPENING LOW THAT WILL BRING A MIX OF PRECIPITATION TO THE AREA
TODAY WILL LIFT OUT ACROSS THE CANADIAN MARITIMES SATURDAY. A BRISK
NORTHWEST FLOW OF COLDER AIR WILL ALREADY BE IN PLACE WITH PLENTY OF
SYNOPTIC SCALE MOISTURE LINGERING BEHIND THE LOW. THIS WILL RESULT
IN WIDESPREAD SNOW SHOWERS AND STEADIER SNOW SOUTHEAST OF THE LAKES.
REGARDING THE LAKE ENHANCEMENT OFF LAKE ERIE...A COMBINATION OF DEEP
MOISTURE...FAVORABLE SNOW GROWTH AND LAKE INSTABILITY (EQUILIBRIUM
LEVELS AROUND 9K FEET) WILL BE IN PLACE THROUGH A GOOD PART OF
SATURDAY. THE WEST TO NORTHWEST FETCH WILL MAINLY IMPACT THE
SOUTHERN TIER...INCLUDING SOUTHERN ERIE AND WYOMING COUNTIES. FROM
EARLY SATURDAY EVENING THROUGH THE FIRST HALF OF SATURDAY
NIGHT...BUFKIT PROFILES SHOW A TREND OF DIMINISHING MOISTURE AND A
LOWERING INVERSION AS HIGH PRESSURE BEGINS TO WORKS EAST FROM THE
OHIO VALLEY. AFTER MIDNIGHT...THE LOW LEVEL MOISTURE AND SNOW GROWTH
BECOME EVEN LESS FAVORABLE FOR SNOW PRODUCTION. BASED ON THESE
TRENDS...A LAKE EFFECT SNOW ADVISORY WILL REMAIN IN EFFECT THROUGH
SATURDAY.
A SIMILAR TREND WILL BE TAKING PLACE SOUTHEAST OF LAKE ONTARIO
SATURDAY. THE FAVORABLE PARAMETERS OF DEEP MOISTURE...SNOW GROWTH
AND INSTABILITY (EQUILIBRIUM LEVELS ABOUT 10K) WILL RESULT IN
STEADIER SNOW THROUGHOUT THE DAY. THE BIGGEST IMPACT FROM
POTENTIALLY SIGNIFICANT SNOWFALL WILL BE FELT OVER OSWEGO COUNTY
WHERE STEADIER SNOW WILL HAVE ALREADY SET UP FRIDAY NIGHT. AS A
RESULT...A LAKE EFFECT SNOW WARNING WILL REMAIN IN EFFECT FOR THAT
AREA THROUGH AT LEAST SATURDAY. THE LOW LEVEL WIND TRAJECTORY ACROSS
LAKE ONTARIO WILL RESULT IN ORGANIZED LAKE SNOWS ACROSS WAYNE AND
NORTHERN CAYUGA COUNTIES AS WELL. BUT SINCE THE BOUNDARY LAYER WINDS
WILL NOT DIRECT THE STEADIER SNOW INTO THESE COUNTIES UNTIL LATE
FRIDAY NIGHT OR SATURDAY MORNING...WE HAVE DECIDED TO GO WITH A LAKE
EFFECT SNOW ADVISORY AT THIS TIME. THIS MAY HAVE TO BE UPGRADED TO A
WARNING IF THE SNOWS BECOME ORGANIZED SOONER THAN EXPECTED. THE LAKE
SNOWS WILL LINGER SOUTHEAST OF LAKE ONTARIO THROUGH AT LEAST THE
FIRST HALF OF SATURDAY NIGHT...BEFORE THE LOWERING INVERSION AND
DECREASING MOISTURE ALLOW THE SNOW TO SUBSIDE LATER IN THE NIGHT.
AREAS OUTSIDE OF THE STEADIER LAKE SNOWS WILL STILL SEE OCCASIONAL
SNOW SHOWERS ON SATURDAY...BUT ACCUMULATIONS ARE EXPECTED TO REMAIN
BELOW ADVISORY CRITERIA. HOWEVER...THE POTENTIAL FOR UPSTREAM
CONNECTIONS TO GEORGIAN BAY AND LAKE HURON COULD BRING HIGHER
ACCUMULATIONS TO THE NIAGARA FRONTIER AND WESTERN SHORES OF LAKE
ONTARIO AS WELL.
THE PRESSURE GRADIENT BETWEEN THE DEPARTING CANADIAN MARITIMES LOW
AND HIGH PRESSURE BUILDING ACROSS THE OHIO VALLEY WILL RESULT IN
BREEZY TO WINDY CONDITIONS ON SATURDAY. THIS WILL HAVE HAVE AN
ADDITIONAL IMPACT ON TRAVEL WITH FREQUENT WHITEOUT CONDITIONS LIKELY
IN THE STEADIER LAKE SNOW AREAS.
FOR SUNDAY...ANY SNOW SHOWERS LINGERING SOUTHEAST OF LAKE ONTARIO
SHOULD END BY LATE MORNING AS HIGH PRESSURE CRESTS OVER THE STATE.
AS THE HIGH SLIDES OFF THE EAST COAST SUNDAY NIGHT...A DEVELOPING
LOW WILL BE TRACKING EAST ACROSS THE UPPER AND CENTRAL GREAT LAKES.
A WARM FRONT EXTENDING EAST OF THE LOW WILL LIFT NORTH ACROSS OUR
AREA AND BRING A CHANCE FOR SOME LIGHT SNOW TO THE NORTH COUNTRY.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
LOOK FOR A WARM AND DRY START TO THE WEEK AS A CLIPPER LOW SLIDES
FROM THE UPPER GREAT LAKES INTO QUEBEC PLACING WESTERN NEW YORK
FIRMLY IN THE WARM SECTOR OF THE LOW UNDER BROAD SOUTHERLY FLOW. ANY
ISENTROPICALLY INDUCED PRECIP WILL OCCUR FAR TO OUR NORTH IN
CANADA...RESULTING IN DRY DAY WITH A DECENT AMOUNT OF SUNSHINE
ACROSS THE AREA HELPING HIGHS TO CLIMB WELL INTO THE 40S.
MODEL CONSENSUS SUGGESTS A DRY NIGHT TUESDAY NIGHT...HOWEVER THERE
ARE SOME DISPARITIES IN THE TEMPERATURE FORECAST BASED ON
DIFFERENCES IN THE TIMING/LOCATION OF A SURFACE LOW PROGGED TO FORM
OVER THE GREAT PLAINS SOMETIME BETWEEN MONDAY NIGHT AND TUESDAY
AFTERNOON. THE GFS IS MUCH FASTER IN DEVELOPING BROAD WARM ADVECTION
ACROSS THE OHIO VALLEY/LOWER GREAT LAKES MONDAY NIGHT AS OPPOSED TO
THE ECMWF THAT ALLOWS COLDER AIR TO FLOW ACROSS THE AREA BEFORE WARM
ADVECTION KICKS IN TUESDAY NIGHT. THIS PRESENTS A VERY SIMILAR
CONUNDRUM TO THE ONE PLAYING OUT RIGHT NOW FOR TONIGHT/S FORECAST
AND GIVEN HOW FAR OUT WE ARE TALKING ABOUT...CHANGES WILL BE VERY
MINOR...STICKING WITH SLIGHTLY ABOVE NORMAL LOWS IN THE UPPER 20S
MONDAY NIGHT.
THE AFOREMENTIONED LOW THAT DEVELOPS OVER THE MIDWEST DURING THE
EARLY PART OF NEST WEEK AND TRACKS ACROSS THE LOWER GREAT LAKES AND
EVENTUALLY ACROSS NEW YORK STATE SOMETIME DURING THE MIDDLE OF NEXT
WEEK WITH TIMING DEPENDENT ON WHICH MODEL YOU GO WITH. GIVEN THE
UNCERTAINTY ALREADY DISCUSSED AND THE LACK OF CONFIDENCE IN ANY ONE
SOLUTION...THE GRIDS FOR TUESDAY AND WEDNESDAY WILL FEATURE
BROAD-BRUSHED CHANCE POPS WITH RUNNING ABOUT 5 DEGREES ABOVE
NORMAL...WHICH IS APPROPRIATE GIVEN THE TRENDS THIS SEASON.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AN AREA OF WARM AIR ADVECTION IN THE MID-LEVELS WILL CONTINUE TO
LIFT NORTHWARD THROUGH THIS MORNING. THIS WILL BRING ART A PERIOD
OF SNOW...WITH ELSEWHERE LIKELY TO JUST SEE SCATTERED SHOWERS
THROUGH THIS MORNING. CIGS SHOULD TREND LOWER AS MORE MOISTURE
BUILDS IN...THOUGH THE SE FLOW ALOFT SHOULD HELP KEEP BUF/IAG/ROC
IN THE MVFR RANGE.
STEADIER RAIN WILL MOVE IN THIS AFTERNOON...WHICH WILL LIKELY
LOWER BOTH VSBY AND CIGS. AS THE LOW DEEPENS AND MOVES ACROSS THE
LAKES...WINDS WILL SHIFT TO THE SW-W LATE AFTERNOON AND EVENING.
THIS WILL TRANSITION RAIN SHOWERS TO SNOW SHOWERS FROM WEST TO EAST.
EXPECT SOME RESTRICTIONS TO REMAIN FOR THE BETTER PART OF THE
NIGHT...AS THE UPPER LEVEL LOW SLOWLY EXITS EAST. LOWEST
CONDITIONS SHOULD BE AT JHW/ART...WHERE LAKE ENHANCEMENT IS MOST
LIKELY.
OUTLOOK...
SATURDAY...VFR...WITH IFR/MVFR IN SCATTERED SNOW SHOWERS AND AREAS
OF LAKE EFFECT SNOW EAST OF THE LAKES.
SUNDAY...VFR...SCTD LAKE EFFECT SNOW SOUTHEASTERN LAKE ONTARIO.
MONDAY...VFR.
&&
.MARINE...
ISSUES GALES FOR A GOOD PORTION OF THE WATERS...AS LOW PRESSURE IS
FORECAST TO INTENSIFY AS IT CROSSES THE WATERS. STRONGEST WINDS
SHOULD BE ON LAKE ERIE THIS EVENING...WITH THIS THEN SHIFTING TO
EASTERN PORTIONS OF LAKE ONTARIO LATER TONIGHT. OTHERWISE...SMALL
CRAFTS UP ELSEWHERE.
WINDS SHOULD REMAIN UP WELL INTO THE WEEKEND...WITH GALES LIKELY TO
TRANSITION TO SMALL CRAFT ADVISORIES FOR SOME TIME.
&&
.TIDES/COASTAL FLOODING...
LOW PRESSURE WILL TRACK ACROSS THE EASTERN LAKES WHILE
INTENSIFYING. THIS WILL CAUSE A RAPID WIND INCREASE AND SHIFT LATE
AFTERNOON AND EVENING...WHICH CAN BE FAVORABLE FOR CAUSING A SIEGE
EVENT. BECAUSE OF THIS POSSIBILITY...HAVE ISSUED A LAKESHORE FLOOD
WATCH FOR ERIE AND CHAUTAUQUA COUNTIES.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...LAKE EFFECT SNOW ADVISORY FROM 6 PM THIS EVENING TO 5 PM EST
SATURDAY FOR NYZ012-019-020-085.
WIND ADVISORY FROM 3 PM THIS AFTERNOON TO 5 AM EST SATURDAY
FOR NYZ001-010-019-020-085.
LAKESHORE FLOOD WATCH FROM 3 PM EST THIS AFTERNOON THROUGH
THIS EVENING FOR NYZ010-019-085.
WINTER STORM WARNING UNTIL 6 AM EST SATURDAY FOR NYZ007-008.
LAKE EFFECT SNOW WARNING FROM 10 PM THIS EVENING TO 5 PM EST
SATURDAY FOR NYZ006.
LAKE EFFECT SNOW ADVISORY FROM 4 AM TO 5 PM EST SATURDAY FOR
NYZ004-005.
WIND ADVISORY FROM 7 PM THIS EVENING TO 5 AM EST SATURDAY FOR
NYZ002>005-011>014-021.
MARINE...SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 5 AM EST
SATURDAY FOR LEZ020.
GALE WARNING FROM 3 PM THIS AFTERNOON TO 5 AM EST SATURDAY
FOR LEZ040-041.
SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 5 AM
EST SATURDAY FOR LOZ030.
GALE WARNING FROM 9 PM THIS EVENING TO 10 AM EST SATURDAY
FOR LOZ043>045-063>065.
SMALL CRAFT ADVISORY UNTIL 6 AM EST SUNDAY FOR LOZ042.
&&
$$
SYNOPSIS...APFFEL
NEAR TERM...APFFEL
SHORT TERM...TJP
LONG TERM...WOOD
AVIATION...APFFEL
MARINE...APFFEL
TIDES/COASTAL FLOODING...APFFEL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
635 AM EST FRI FEB 24 2012
.SYNOPSIS...
WINDY AND WARM CONDITIONS TODAY WILL PRECEDE A FAST MOVING LINE
OF STRONG THUNDERSTORMS ASSOCIATED WITH A COLD FRONT. SEASONABLE
TO SLIGHTLY COOL WEEKEND WEATHER WILL BE FOLLOWED BY A GRADUAL
WARMUP LASTING MUCH OF THE UPCOMING WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM FRIDAY...STRONG TO SEVERE CONVECTION AHEAD OF AN
APPROACHING COLD FRONT WILL BE THE WEATHER STORY THROUGH THIS
EVENING. MODELS INDICATE THE WEST TO EAST MOVEMENT OF THE COLD FRONT
SLATED FOR PASSAGE BY MID EVENING. HIGH SHEAR LOW CAPE SEVERE
EVENT...BUT IN THIS CASE SFC BASED CAPE IS MORE PREVALENT AND
ILLUSTRATED BY LATEST MODELS IE. LATEST HRRR MODEL RUNS...THEN
PREVIOUS POTENTIAL SEVERE WX EVENTS OF THIS WINTER SEASON. FROM
NAMBUFR SOUNDINGS ACROSS SE N.C...PWS PEAK AROUND 1.5 INCHES THIS
AFTERNOON...LI -4...CAPE UP TO 1250. 900MB WINDS 50+ KT. THESE
PARAMETERS AS WELL AS OTHER TSTM PARAMETERS POINT TO STRONG TO
SEVERE CONVECTION AHEAD OF THE COLD FRONT. VIA MODEL SOUNDINGS...THE
CONVECTION WILL ILLUSTRATE WEST TO EAST MOVEMENT WITH STORM MOTIONS
OF 40-50 KT...VIA NAMBUFR SOUNDINGS. HIGHLIGHTED THE SEVERE WX
THREAT FROM MIDDAY THROUGH EARLY THIS EVENING. ANY SVR WATCHES
ISSUED BY SPC WILL FURTHER REFINE THIS TIMELINE. MAX TEMPS TODAY ON
THE HIGHER SIDE OF MOS GUIDANCE...GIVEN ANOTHER NEARLY FULL DAYS
WORTH OF THIS UNUSUAL WARM/MOIST AIRMASS TO AFFECT THE ILM CWA PRIOR
TO THE CFP TONIGHT. EXPECT WIDESPREAD 70S EXCEPT LOWER ALONG THE
IMMEDIATE COAST DUE TO SSTS IN THE 50S. SW WINDS TO GUST 25 TO 35
MPH BY MIDDAY THROUGH THIS AFTERNOON.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...MUCH DRIER AND CONSIDERABLY COOLER AIR ADVECTION
IN ON SATURDAY AS 1030MB HIGH DIVES INTO TX AND GULF STATES. TEMPS
STILL QUITE CLOSE TO CLIMO SAT AFTERNOON BUT CONTINUED CAA SAT NIGHT
TO BRING LOWS ALMOST A CATEGORY BELOW NORMAL. SUNDAY OUR ONE COOL
DAY AS THE HIGH MOVES ACROSS AND MIXING IS SHALLOW. A LITTLE WARM
AND MOIST ADVECTION KICKS IN SUNDAY NIGHT. FOR NOW THIS SHOULD ONLY
BRING SOME ADDED CLOUD COVER AND MORE SEASONABLE LOW TEMPS...AND
PROBABLY NOT THE CHANCE FOR RAIN AS HINTED BY SOME GUIDANCE. CUTOFF
LOW CURRENTLY OVER BAJA CA OPENS UP AND ENTERS THE FLOW AND GUIDANCE
IS LIKELY HANGING ON TO RAIN WITH THIS FEATURE FOR TOO LONG DESPITE
HOW MUCH IT WEAKENS AS IT CROSSES OUR LONGITUDE. WILL OPT FOR THE
WEAKEST AND MOST SOUTH-SUPPRESSED SOLUTION.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 3 AM FRIDAY...BACK INTO THE FAMILIAR TERRITORY OF MILD
CONDITIONS BY MONDAY AS LOW LEVEL HIGH MOVES OFF THE COAST. MID
LEVEL FLOW WILL BE QUITE FLAT KEEPING THAT PART OF THE COLUMN DRY.
LOW LEVEL MOISTURE MAY TRY TO ADVECT AROUND THE WEST SIDE OF THE
HIGH AS INDICATED BY SOME GUIDANCE BUT PROBABLY NOT TO THE EXTENT
INDICATED. WILL ONLY SHOW A SMALL AND GRADUAL INCREASE IN POPS BY
TUESDAY AS COLD FRONT APPROACHES AND TIGHTENS THE CHANNEL OF
MOISTURE ADVECTION. BEST CHANCE FOR MEASURABLE RAINFALL COMES WITH
ACTUAL FROPA WHICH LOOKS LIKE LATE WEDNESDAY OR WEDNESDAY NIGHT.
AMPLITUDE ALOFT REMAINS VERY LOW SO EVEN POST FROPA TEMPS WILL BE
WARMER THAN NORMAL...JUST NOT TO THE EXTENT OF THOSE THROUGH THE MID
WEEK PERIOD.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AS OF 12Z...SEA FOG IS OCCURRING THIS MORNING WITHIN A MARINE LAYER
THAT IS PRIMARILY EAST OF THE MYR/ILM TERMINALS DUE TO SOUTHWESTERLY
COMPONENT WINDS. BUT THE CRE TERMINAL UNFORTUNATELY IS WITHIN THIS
MARINE LAYER DUE TO ITS LOCATION ON THE COAST AND IS RESULTING IN
MVFR VISIBILITIES...WITH A SCATTERED TO BROKEN 500 FOOT STRATUS
LAYER. THE FLO/LBT TERMINALS ARE CURRENTLY EXPERIENCING LOW VFR
LEVEL CEILINGS. DUE TO SOUTHWESTERLY COMPONENT WINDS EXPECT THE
CHANCE OF IFR TO REMAIN LOW AT THE MYR/ILM TERMINALS...BUT AT THE
CRE TERMINALS THERE WILL CONTINUE TO BE A HIGHER CHANCE OF IFR
OCCURRENCE THROUGH 14-15Z. THE FLO/LBT TERMINALS ARE CURRENTLY
EXPERIENCING LOW VFR LEVEL CEILINGS. EXCEPT FOR CRE...MVFR
CONDITIONS WILL BE MOST LIKELY THIS MORNING WITH TEMPO SHOWERS
MAINLY AT FLO/LBT.
A STRONG COLD FRONT WILL MOVE THROUGH THE TERMINALS LATE THIS
AFTERNOON AND EVENING WITH A PRE-FRONTAL TROUGH LIKELY.
THUNDERSTORMS/TEMPO IFR WILL BE LIKELY THIS AFTERNOON AT FLO/LBT AND
LATE AFTERNOON AND EVENING AT THE COASTAL TERMINALS. AFTER FROPA
EXPECT RAPID IMPROVEMENT TO VFR WITH WINDS SHIFTING TO THE NORTHWEST.
EXTENDED OUTLOOK...LOW CHANCE OF IFR/FOG EARLY MONDAY AND TUESDAY
WITH SHOWERS POSSIBLE LATER TUESDAY. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM FRIDAY...STRONG SOUTHWEST SCA CRITERIA WINDS TO AFFECT
THE ILM COASTAL WATERS AHEAD OF THE COLD FRONT INTO THIS EVENING.
POST FRONTAL TOGHTENED SFC PG NW WINDS AFTER MIDNIGHT...COMBINED
WITH CAA SURGE...TO CONTINUE A STRONGLY WORDED SCA WITH FEW GUSTS
REACHING GALE FORCE...35 KT. AS A RESULT...THE NEXT 24 HRS ACROSS
THE ILM COASTAL WATERS ARE NOT RECOMMENDED FOR DINGYS. LOOK FOR SEAS
TO PEAK IN THE 5 TO 9 FT RANGE ...HIGHEST SEAS ACROSS THE SOUTHERN
WATERS OFF CAPE FEAR. 41013 FRYING PAN SHOALS BUOY WELL BEYOND THE
COASTAL WATERS...COULD PEAK 10-13 FT RANGE DUE TO SSTS IN THE 60S
ALLOWING GALE FORCE SUSTAINED WINDS TO MIX DOWN TO THE OCEAN SFC.
OVERALL...LOOK FOR PERIODS IN THE 5 TO 8 SECOND RANGE.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 AM FRIDAY...SATURDAYS CONDITIONS MAY STILL REQUIRE SOME
CAUTIONARY HEADLINES AS THE MARINE ZONES FIND THEMSELVES STILL IN
MODERATELY STRONG POST COLD FRONTAL FLOW. HIGH PRESSURE BUILDS INTO
THE CAROLINAS ON SUNDAY BRINGING A NORTHEASTERLY WIND THAT WILL
DIMINISH AS THE AFTERNOON WEARS ON. A GENERAL 2 TO 4 FT SEA STATE
WILL ABATE AS THIS OCCURS. A SLIGHT VEER OF THE VERY LIGHT WINDS BY
SUNDAY NIGHT WILL OCCUR AS A WEAK TROUGH DEVELOPS OFF THE COAST.
SEAS WILL HAVE SETTLED ALL THE WAY DOWN TO JUST 2 FT OR LESS BY THE
END OF THE PERIOD.
LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 3 AM FRIDAY...A VERY WEAK PRESSURE GRADIENT WILL BE IN PLACE
ON MONDAY. HIGH PRESSURE WILL BE RATHER SPREAD OUT ACROSS THE
SOUTHEAST AND MID ATLANTIC STATES AS WELL AS OVER THE WESTERN
ATLANTIC OCEAN. SO WHILE IT IS FAIRLY CERTAIN THAT WIND SPEEDS WILL
BE LOW THERE IS SOME INHERENT UNCERTAINTY REGARDING WHAT THE WIND
DIRECTION WILL BE. SEAS WILL ACCORDINGLY BE ABOUT AS SMALL AS THEY
GET AND RUN LESS THAN 2 FT ESPECIALLY CLOSE TO SHORE. NOT MUCH
CHANGE IN WIND SPEED BUT A BETTER DEFINED ONSHORE WIND DIRECTION
WILL BECOME ESTABLISHED AS THE CENTER OF THE HIGH DRIFTS EAST.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST SATURDAY FOR
AMZ250-252-254-256.
&&
$$
NEAR TERM...DCH
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...DCH/HDL
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
1030 AM EST FRI FEB 24 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE NORTHEAST ACROSS OHIO TO LAKE ERIE AND
SOUTHERN ONTARIO CANADA. THE LOW WILL FORCE A COLD FRONT EAST ACROSS
THE AREA LATER TONIGHT. A TROUGH WILL MOVE SOUTH ACROSS THE AREA
SATURDAY MORNING. HIGH PRESSURE WILL BUILD EAST INTO THE REGION LATE
SATURDAY NIGHT INTO SUNDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WILL ADD WIND ADVISORY FOR THE TOL AREA TO BE CONSISTENT WITH IWA
WIND ADVISORY AND THE HIGH WIND WARNING JUST SOUTH NEAR FDY.
PREVIOUS DISCUSSION:
MAIN CONCERN FOR THE AFTERNOON IS THAT WIND GUSTS WILL REACH NEAR
50 KTS ACROSS THE SOUTHERN AND EASTERN PORTION OF THE AREA. BREAK
IN THE CLOUD COVER OVER WESTERN OHIO THIS MORNING WILL PERMIT SOME
HEATING AND ALLOW THE BOUNDARY LAYER TO MIX/DEEPEN AND TAP HIGHER
WINDS ALOFT WHICH WILL LIKELY MIX TO THE SURFACE. BUFKIT SOUNDINGS
FOR THE AFTERNOON FROM MFD TO YNG AND CLE AND ERI SHOW THE MIXED
LAYER TAPING 60KT WINDS. THE HRRR MODEL ALSO PRODUCES SURFACE WIND
GUSTS OF 45 TO 50 KT THIS AFTERNOON. WILL UPGRADE THE WIND
ADVISORY TO A HIGH WIND WARNING. ONLY MINOR OTHER CHANGES PLANNED.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
THE LAKE EFFECT IS EXPECTED TO PICK UP IN EARNEST TONIGHT AS FLOW
BECOMES WELL ALIGNED. MAINLY A WEST TO WEST NORTHWEST FLOW IS
EXPECTED TONIGHT AND THIS SHOULD ENHANCE THE LAKE EFFECT SNOWS OVER
THE EXTREME NORTHEAST PORTION OF THE AREA. LAKE TO AIR TEMP
DIFFERENCE IS NOT ALL THAT EXCITING WITH CONDITIONAL INSTABILITY
EXPECTED. HOWEVER...WITH DEEP MOISTURE AND PERSISTENT FLOW
EXPECTED...LOOKING AT SNOW ACCUMULATIONS REACHING THE THRESHOLD FOR
LAKE EFFECT SNOW ADVISORY CRITERIA STARTING AROUND 1 AM EST TONIGHT.
SNOWFALL ACCUMULATIONS COULD REACH NEARLY A FOOT IN SOME OF THE
HIGHER ELEVATIONS. HOWEVER...SNOW ACCUMULATIONS SHOULD BE SPREAD OUT
OVER SUCH A LONG PERIOD OF TIME THAT WE DONT ANTICIPATE ISSUING A
WARNING AT THIS TIME.
AS THE HIGH PRESSURE BUILDS EAST SATURDAY NIGHT...THE FLOW WILL BE
CUT OFF RATHER QUICKLY AND THIS WILL BRING AN END TO THE LAKE EFFECT
SNOW.
FOR THE REST OF THE FORECAST AREA...LIGHT SNOW IS EXPECTED OVER THE
REGION AND LOOKING AT LIGHT SNOW AMOUNTS MAINLY DUE TO THE SYNOPTIC
SNOW WITH THE LOW PRESSURE. THE SNOW ACCUMULATIONS OUTSIDE THE LAKE
EFFECT AREAS OF NORTHEAST OHIO AND NORTHWEST PENNSYLVANIA WILL TAPER
OFF INTO SATURDAY AND THEN DISSIPATE ENTIRELY BY SATURDAY NIGHT.
SNOW ACCUMULATIONS OF 1 TO 3 INCHES POSSIBLE.
AS HIGH PRESSURE RETURNS SUNDAY INTO EARLY MONDAY...FAIR WEATHER
WILL RETURN AS WELL. THE HIGH WILL MOVE EAST TO THE ATLANTIC OCEAN
ALLOWING ANOTHER ROUND OF LOW PRESSURE MOVE INTO THE WESTERN GREAT
LAKES REGION. THE LOW IS EXPECTED TO SPREAD MORE PRECIPITATION INTO
THE REGION LATE SUNDAY NIGHT. MOST OF THE MOISTURE ASSOCIATED WITH
THE FEATURE WILL REMAIN NORTH OF THE STORM CENTER SO THE
PRECIPITATION THREAT WILL BE MINIMIZED. FAIR WEATHER RETURNS FOR
MONDAY AND MONDAY NIGHT.
TEMPERATURES THROUGH THIS PERIOD ARE EXPECTED TO BE ON THE INCREASE
WITH WARM AIR ADVECTION TAKING PLACE ON THE WEST SIDE OF THE HIGH
PRESSURE CENTER. AS LOW MOVES NORTHEAST OF THE REGION
MONDAY...TEMPERATURES WILL DROP BACK INTO THE 20S AGAIN FOR LOWS
MONDAY NIGHT.
&&
.LONG TERM /TUESDAY THROUGH THURSDAY/...
MODELS ARE ACTUALLY IN DECENT AGREEMENT WITH A STORM SYSTEM THAT
WILL MOVE FROM THE CENTRAL PLAINS ON TUESDAY TO THE CENTRAL GREAT
LAKES BY WEDNESDAY. WE SHOULD BE ON THE WARM SIDE OF THIS SYSTEM
YET AGAIN. HOWEVER AS THE PRECIPITATION STARTS TUESDAY NIGHT INTO
EARLY WEDNESDAY THERE COULD BE SOME SNOW FOR THE NORTHERN HALF OF
THE REGION. MORE DETAILS ON THIS NEXT NEXT FEW DAYS. SO EXPECT TO
SEE RAIN FOR MOST LOCATIONS FOR WEDNESDAY. IT WILL BE COOLER IN THE
WAKE OF THIS STORM SYSTEM ON THURSDAY BUT NOT COLD ENOUGH TO
GENERATE ANYTHING MORE THAN A FEW LAKE EFFECT SNOW SHOWERS.
AFTER HIGHS IN THE MIDDLE TO UPPER 40S ON TUESDAY AND WEDNESDAY IT
APPEARS WE WILL REMAIN IN THE MIDDLE 30S TO NEAR 40 ON THURSDAY.
&&
.AVIATION /16Z FRIDAY THROUGH TUESDAY/...
STRONG LOW PRESSURE WILL MOVE TO NEAR LAKE ERIE THIS MORNING AND
THEN NORTHEAST TO LAKE ONTARIO BY THIS EVENING. THIS WILL BRING AN
EXTREME MIX OF CONDITIONS ACROSS THE REGION THROUGH THE DAY.
SEVERAL LOCATIONS ACROSS THE EAST WILL ACTUALLY SEE VFR CONDITIONS
FOR A SHORT PERIOD THIS MORNING. AN AREA OF SHOWERS WILL MOVE
ACROSS THE REGION ALONG A COLD FRONT WITH MVFR CONDITIONS LIKELY.
AS THESE SHOWERS PASS THE WINDS WILL INCREASE FROM THE SOUTHWEST
AND WEST. WIND GUSTS IN THE 35 TO 45 KNOT RANGE WILL BE COMMON FOR
MOST LOCATIONS. AS THE COLDER AIR RETURNS EXPECT ALL LOCATIONS TO
RETURN TO MVFR CONDITIONS. WHERE SNOW OCCURS THERE WILL BE PERIODS
OF IFR...ESPECIALLY NORTH OF A LINE FROM KFDY TO KERI. WINDS WILL
DECREASE THROUGH THE EVENING. LOCATIONS DOWNWIND OF LAKE ERIE WILL
CONTINUE TO SEE SNOW SHOWERS WITH PERIODIC IFR CONDITIONS.
ELSEWHERE MVFR CEILINGS WILL CONTINUE.
OUTLOOK...PERIODS OF NON-VFR LIKELY SATURDAY THROUGH SATURDAY
EVENING.
&&
.MARINE...
LOW PRESSURE OVER EAST CENTRAL INDIANA WILL REACH LAKE ERIE BY MID
MORNING THEN CONTINUE TO LAKE ONTARIO BY FRIDAY AFTERNOON. THIS WILL
CAUSE WINDS TO 34 TO 40 KNOT GALES THIS AFTERNOON. DID NOT INCLUDE
THE WESTERN BASIN IN THE GALE WARNING SO HAD TO ISSUE A SMALL CRAFT
ADVISORY WITH WINDS TO 30 KNOTS.
AS A TROUGH OF LOW PRESSURE CROSSES LAKE ERIE SATURDAY IT WILL HELP
TO KEEP WINDS UP ENOUGH TO KEEP AT SMALL CRAFT ADVISORY CONDITIONS
GOING INTO AT LEAST SATURDAY EVENING.
A RIDGE WILL BUILD ACROSS THE LAKE EARLY SUNDAY...SHIFTING EAST BY
MONDAY AS LOW PRESSURE MOVES TO THE CENTRAL GREAT LAKES. A COLD
FRONT WILL MOVE ACROSS LAKE ERIE TUESDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...HIGH WIND WARNING UNTIL 8 PM EST THIS EVENING FOR OHZ008>013-
017>022-027>032-036>038-047.
HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR OHZ014-023-
033-089.
WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR OHZ003-006-007.
PA...HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR PAZ001>003.
LAKE EFFECT SNOW ADVISORY FROM 1 AM TO 7 PM EST SATURDAY FOR
PAZ001>003.
MARINE...GALE WARNING UNTIL 3 AM EST SATURDAY FOR LEZ061-144>149-
164>169.
SMALL CRAFT ADVISORY UNTIL 9 PM EST SATURDAY FOR LEZ142-143.
&&
$$
SYNOPSIS...LOMBARDY
NEAR TERM...LOMBARDY
SHORT TERM...REL
LONG TERM...MULLEN
AVIATION...MULLEN
MARINE...MULLEN
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
954 AM EST FRI FEB 24 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE NORTHEAST ACROSS OHIO TO LAKE ERIE AND
SOUTHERN ONTARIO CANADA. THE LOW WILL FORCE A COLD FRONT EAST ACROSS
THE AREA LATER TONIGHT. A TROUGH WILL MOVE SOUTH ACROSS THE AREA
SATURDAY MORNING. HIGH PRESSURE WILL BUILD EAST INTO THE REGION LATE
SATURDAY NIGHT INTO SUNDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MAIN CONCERN FOR THE AFTERNOON IS THAT WIND GUSTS WILL REACH NEAR
50 KTS ACROSS THE SOUTHERN AND EASTERN PORTION OF THE AREA. BREAK
IN THE CLOUD COVER OVER WESTERN OHIO THIS MORNING WILL PERMIT SOME
HEATING AND ALLOW THE BOUNDARY LAYER TO MIX/DEEPEN AND TAP HIGHER
WINDS ALOFT WHICH WILL LIKELY MIX TO THE SURFACE. BUFKIT SOUNDINGS
FOR THE AFTERNOON FROM MFD TO YNG AND CLE AND ERI SHOW THE MIXED
LAYER TAPING 60KT WINDS. THE HRRR MODEL ALSO PRODUCES SURFACE WIND
GUSTS OF 45 TO 50 KT THIS AFTERNOON. WILL UPGRADE THE WIND
ADVISORY TO A HIGH WIND WARNING. ONLY MINOR OTHER CHANGES PLANNED.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
THE LAKE EFFECT IS EXPECTED TO PICK UP IN EARNEST TONIGHT AS FLOW
BECOMES WELL ALIGNED. MAINLY A WEST TO WEST NORTHWEST FLOW IS
EXPECTED TONIGHT AND THIS SHOULD ENHANCE THE LAKE EFFECT SNOWS OVER
THE EXTREME NORTHEAST PORTION OF THE AREA. LAKE TO AIR TEMP
DIFFERENCE IS NOT ALL THAT EXCITING WITH CONDITIONAL INSTABILITY
EXPECTED. HOWEVER...WITH DEEP MOISTURE AND PERSISTENT FLOW
EXPECTED...LOOKING AT SNOW ACCUMULATIONS REACHING THE THRESHOLD FOR
LAKE EFFECT SNOW ADVISORY CRITERIA STARTING AROUND 1 AM EST TONIGHT.
SNOWFALL ACCUMULATIONS COULD REACH NEARLY A FOOT IN SOME OF THE
HIGHER ELEVATIONS. HOWEVER...SNOW ACCUMULATIONS SHOULD BE SPREAD OUT
OVER SUCH A LONG PERIOD OF TIME THAT WE DONT ANTICIPATE ISSUING A
WARNING AT THIS TIME.
AS THE HIGH PRESSURE BUILDS EAST SATURDAY NIGHT...THE FLOW WILL BE
CUT OFF RATHER QUICKLY AND THIS WILL BRING AN END TO THE LAKE EFFECT
SNOW.
FOR THE REST OF THE FORECAST AREA...LIGHT SNOW IS EXPECTED OVER THE
REGION AND LOOKING AT LIGHT SNOW AMOUNTS MAINLY DUE TO THE SYNOPTIC
SNOW WITH THE LOW PRESSURE. THE SNOW ACCUMULATIONS OUTSIDE THE LAKE
EFFECT AREAS OF NORTHEAST OHIO AND NORTHWEST PENNSYLVANIA WILL TAPER
OFF INTO SATURDAY AND THEN DISSIPATE ENTIRELY BY SATURDAY NIGHT.
SNOW ACCUMULATIONS OF 1 TO 3 INCHES POSSIBLE.
AS HIGH PRESSURE RETURNS SUNDAY INTO EARLY MONDAY...FAIR WEATHER
WILL RETURN AS WELL. THE HIGH WILL MOVE EAST TO THE ATLANTIC OCEAN
ALLOWING ANOTHER ROUND OF LOW PRESSURE MOVE INTO THE WESTERN GREAT
LAKES REGION. THE LOW IS EXPECTED TO SPREAD MORE PRECIPITATION INTO
THE REGION LATE SUNDAY NIGHT. MOST OF THE MOISTURE ASSOCIATED WITH
THE FEATURE WILL REMAIN NORTH OF THE STORM CENTER SO THE
PRECIPITATION THREAT WILL BE MINIMIZED. FAIR WEATHER RETURNS FOR
MONDAY AND MONDAY NIGHT.
TEMPERATURES THROUGH THIS PERIOD ARE EXPECTED TO BE ON THE INCREASE
WITH WARM AIR ADVECTION TAKING PLACE ON THE WEST SIDE OF THE HIGH
PRESSURE CENTER. AS LOW MOVES NORTHEAST OF THE REGION
MONDAY...TEMPERATURES WILL DROP BACK INTO THE 20S AGAIN FOR LOWS
MONDAY NIGHT.
&&
.LONG TERM /TUESDAY THROUGH THURSDAY/...
MODELS ARE ACTUALLY IN DECENT AGREEMENT WITH A STORM SYSTEM THAT
WILL MOVE FROM THE CENTRAL PLAINS ON TUESDAY TO THE CENTRAL GREAT
LAKES BY WEDNESDAY. WE SHOULD BE ON THE WARM SIDE OF THIS SYSTEM
YET AGAIN. HOWEVER AS THE PRECIPITATION STARTS TUESDAY NIGHT INTO
EARLY WEDNESDAY THERE COULD BE SOME SNOW FOR THE NORTHERN HALF OF
THE REGION. MORE DETAILS ON THIS NEXT NEXT FEW DAYS. SO EXPECT TO
SEE RAIN FOR MOST LOCATIONS FOR WEDNESDAY. IT WILL BE COOLER IN THE
WAKE OF THIS STORM SYSTEM ON THURSDAY BUT NOT COLD ENOUGH TO
GENERATE ANYTHING MORE THAN A FEW LAKE EFFECT SNOW SHOWERS.
AFTER HIGHS IN THE MIDDLE TO UPPER 40S ON TUESDAY AND WEDNESDAY IT
APPEARS WE WILL REMAIN IN THE MIDDLE 30S TO NEAR 40 ON THURSDAY.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
STRONG LOW PRESSURE WILL MOVE TO NEAR LAKE ERIE THIS MORNING AND
THEN NORTHEAST TO LAKE ONTARIO BY THIS EVENING. THIS WILL BRING AN
EXTREME MIX OF CONDITIONS ACROSS THE REGION THROUGH THE DAY.
SEVERAL LOCATIONS ACROSS THE EAST WILL ACTUALLY SEE VFR CONDITIONS
FOR A SHORT PERIOD THIS MORNING. AN AREA OF SHOWERS WILL MOVE
ACROSS THE REGION ALONG A COLD FRONT WITH MVFR CONDITIONS LIKELY.
AS THESE SHOWERS PASS THE WINDS WILL INCREASE FROM THE SOUTHWEST
AND WEST. WIND GUSTS IN THE 35 TO 45 KNOT RANGE WILL BE COMMON FOR
MOST LOCATIONS. AS THE COLDER AIR RETURNS EXPECT ALL LOCATIONS TO
RETURN TO MVFR CONDITIONS. WHERE SNOW OCCURS THERE WILL BE PERIODS
OF IFR...ESPECIALLY NORTH OF A LINE FROM KFDY TO KERI. WINDS WILL
DECREASE THROUGH THE EVENING. LOCATIONS DOWNWIND OF LAKE ERIE WILL
CONTINUE TO SEE SNOW SHOWERS WITH PERIODIC IFR CONDITIONS.
ELSEWHERE MVFR CEILINGS WILL CONTINUE.
OUTLOOK...PERIODS OF NON-VFR LIKELY SATURDAY THROUGH SATURDAY
EVENING.
&&
.MARINE...
LOW PRESSURE OVER EAST CENTRAL INDIANA WILL REACH LAKE ERIE BY MID
MORNING THEN CONTINUE TO LAKE ONTARIO BY FRIDAY AFTERNOON. THIS WILL
CAUSE WINDS TO 34 TO 40 KNOT GALES THIS AFTERNOON. DID NOT INCLUDE
THE WESTERN BASIN IN THE GALE WARNING SO HAD TO ISSUE A SMALL CRAFT
ADVISORY WITH WINDS TO 30 KNOTS.
AS A TROUGH OF LOW PRESSURE CROSSES LAKE ERIE SATURDAY IT WILL HELP
TO KEEP WINDS UP ENOUGH TO KEEP AT SMALL CRAFT ADVISORY CONDITIONS
GOING INTO AT LEAST SATURDAY EVENING.
A RIDGE WILL BUILD ACROSS THE LAKE EARLY SUNDAY...SHIFTING EAST BY
MONDAY AS LOW PRESSURE MOVES TO THE CENTRAL GREAT LAKES. A COLD
FRONT WILL MOVE ACROSS LAKE ERIE TUESDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...HIGH WIND WARNING UNTIL 8 PM EST THIS EVENING FOR OHZ008>013-
017>022-027>032-036>038-047.
HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR OHZ014-023-
033-089.
PA...HIGH WIND WARNING UNTIL 10 PM EST THIS EVENING FOR PAZ001>003.
LAKE EFFECT SNOW ADVISORY FROM 1 AM TO 7 PM EST SATURDAY FOR
PAZ001>003.
MARINE...GALE WARNING UNTIL 3 AM EST SATURDAY FOR LEZ061-144>149-
164>169.
SMALL CRAFT ADVISORY UNTIL 9 PM EST SATURDAY FOR LEZ142-143.
&&
$$
SYNOPSIS...LOMBARDY
NEAR TERM...LOMBARDY
SHORT TERM...REL
LONG TERM...MULLEN
AVIATION...MULLEN
MARINE...MULLEN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
616 AM EST FRI FEB 24 2012
.SYNOPSIS...
AN INTENSE AREA OF LOW PRESSURE WILL PASS JUST TO THE NORTHWEST OF
THE AREA DURING THE MIDDAY AND AFTERNOON HOURS TODAY...DRIVING A
STRONG COLD FRONT EAST ACROSS THE STATE. COLDER AIR WILL SURGE
INTO THE REGION FROM WEST TO EAST BEHIND THE COLD FRONT FROM LATE
THIS AFTERNOON THROUGH THE EVENING. STRONG GUSTY WINDS WILL ALSO
ACCOMPANY THE COLD FRONTAL PASSAGE. SEASONABLY COLD AND WINDY
CONDITIONS ARE EXPECTED ON SATURDAY WITH LAKE EFFECT SNOWS
DOWNWIND OF LAKE ERIE AND OVER THE WESTERN HIGH TERRAIN. HIGH
PRESSURE WILL RETURN TO THE AREA ON SUNDAY BEFORE YIELDING TO A
FRONTAL SYSTEM LIFTING THROUGH THE GREAT LAKES INTO SOUTHEASTERN
CANADA ON MONDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
INITIAL SLUG OF WAA PCPN HAS MOVED NEWD INTO THE POCONOS AND
CATSKILLS. THE LATEST RADAR SHOWS AREA OF SHOWERS CONFINED MAINLY TO
SRN PA. EXPIRED THE WINTER WX ADVISORY FOR THE NRN TIER AS SNOW IS
LONE GONE AND SFC-850MB TEMPS ARE SLOWLY WARMING. LATEST RUC DATA
AND MESO OBS SUGGEST P TYPES SHOULD BE ALL RAIN.
COMPLEX AREA OF LOW PRES CENTERED JUST EAST OF CMH AT 10Z WILL
SLOWLY DEEPEN AND OCCLUDE NWD TO VCNTY LAKE ERIE BY 18Z. SFC PRES
FALLS IN THE LEE OF THE APPALACHIANS WILL INDUCE A SECONDARY
TRIPLE POINT LOW SOUTH OF THE MASON DIXON LINE NEAR THE WV/MD
PANHANDLES...WITH ERODING STABILITY IN THE NARROW WARM SECTOR AHEAD
OF TRAILING COLD FRONT SWEEPING ACROSS THE APPALACHIAN SPINE. MODEL
DATA SHOWS THE NRN EXTENT OF THE WARM SECTOR POSSIBLY BREAKING INTO
S-CENTRAL PA AND FAR LWR SUSQ VLY THIS AFTN. SREF GUID SUPPORTS
MENTION OF SCHC T OVR THE SRN TIER.
WV AND IR SATL SHOWS MUCH OF CENTRAL PA IN THE DRY SLOT WITH
POTENT H5 VORTEX ROTATING THRU THE MIDWEST. THE MODELS ARE GOOD
AGREEMENT WITH THE SYSTEM ALOFT AS IT TAKES ON A SLGT NEGATIVE
TILT PIVOTING NEWD ACRS THE ERN GRT LKS. STG WAA AND ISENTROPIC LIFT
TO THE N/NE OF PRIMARY LOW INTERSECTING RETREATING WARM FNTL ZONE
AT THE NOSE OF S/SW LLJ WILL CONTINUE TO PRODUCE SCT TO NMRS SHOWERS
INTO THE AFTN. BASIN AVG QPF WILL BE ON THE LGT SIDE THRU 18Z WITH
AMTS LESS THAN 0.25 INCHES. EXPECT SOME ENHANCEMENT OF PCPN OVR ERN
PA LATER THIS AFTN INTO THE EVE AS RIBBON OF ABOVE NORMAL PWATS IS
DRAWN NWD AHEAD OF SHARPENING COLD FRONT.
THE COLD FRONT SHOULD CLEAR ERN AREAS BY 00Z. STG DEEP LYR CAA WILL
PROMOTE VERY EFFICIENT BLYR MIXING...WHICH SHOULD TAP 50-60KT WINDS
AT 850MB AND TRANSFER A GOOD PORTION OF THE HIGH MOMENTUM AIR ALOFT
DOWN TO THE SFC. THE TIMING OF THE STRONGEST WIND GUSTS /FROM MID
AFTN IN THE WEST TO MID EVE IN THE EAST/ IS LATER THAN PREVIOUSLY
FCST AND THEREFORE EXTENDED HWW/WIND ADY THRU 12Z SAT. COULD SEE THE
ADVY GOING FURTHER INTO SAT BUT WILL LET LATER SHIFTS HANDLE THIS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SATURDAY/...
FCST BECOMES MORE STRAIGHTFORWARD DURING THE SECOND HALF OF DAY 1.
THE COLD FRONT WILL PLOW THROUGH THE CWA...LEAVING BEHIND SEASONABLY
COLD AND VERY BLUSTERY CONDITIONS WITH TEMPERATURES FALLING INTO
THE 20S AND 30S. ASIDE FROM THE STRONG WINDS...EXPECT LAKE EFFECT
AND UPSLOPE SNOW SHOWERS TO DEVELOP IN GUSTY POST-FRONTAL WNWLY
FLOW REGIME. HAVE ISSUED A LAKE EFFECT SNOW ADVY FOR THE FAVORED
SNOWBELT REGION/NW MTNS. ALSO EXPECT A FEW TO SEVERAL INCHES OF
WIND-DRIVEN SNOW ACCUM OVER LAUREL HIGHLANDS...AND LATER SHIFTS MAY
NEED TO HOIST A HEADLINE FOR THIS AREA.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
COLDEST AIR IN ALMOST 2 WEEKS ARRIVES ON SAT...WITH BRISK
NORTHWEST WINDS CONTINUING TO FREQUENTLY GUST IN EXCESS OF 30 MPH
ACROSS MUCH OF THE CWA. HIGHS WILL FALL BACK NOTICEABLY...BUT
STILL BE JUST 3-5F BELOW NORMAL FOR LATE FEBRUARY. MAX TEMPS WILL
RANGE FROM THE UPPER 20S IN THE MTNS TO LOWER 40S IN THE SE ZONES.
SAT NIGHT BRINGS TEMPS IN THE TEENS AND 20S AS CLOUDS CONTINUE TO
GRADUALLY DECREASE AND SNOW SHOWERS COME TO AN END AFTER MIDNIGHT
AS THE 850 MB RIDGE SLIDES INTO WRN PENN AND THE BASE OF THE
SUBSIDENCE INVERSION DROPS TO BELOW 3 KFT AGL. A FEW LOCATIONS
ACROSS THE NRN MTNS WITH SNOW COVER COULD DIP INTO THE HIGH SINGLE
DIGITS TWD 12Z SUNDAY.
UPPER TROUGH QUICKLY LIFTS OUT BY LATE IN THE WEEKEND...RETURNING
PA TO A MILD ZONAL FLOW. ONE PACIFIC SHORTWAVE SHOULD RAPIDLY PASS
TO OUR NORTH LATE MONDAY BRINGING JUST SOME PERIODS OF MAINLY MID
AND HIGH CLOUDS...BUT PRODUCING LITTLE OR NO PRECIP AND KEEPING
IT BREEZY.
ANOTHER POTENTIALLY MORE SIGNIFICANT SYSTEM SHOULD IMPACT THE
REGION FOR WEDNESDAY INTO THURSDAY. 00Z US/EURO MDL CONSENSUS
INDICATES A SFC LOW TRACK THRU THE UPPER MIDWEST/UPPER GLAKES
REGION WITH BLOCKING HIGH PRES OVR NEW ENGLAND. THIS SCENARIO
COULD PRODUCE SOME MINOR AMTS OF SNOW/MIXED PRECIP ACROSS MAINLY
NRN PA WED INTO THU. HOWEVER...THE AIRMASS AHEAD OF THIS SYSTEM
APPEARS QUITE MILD...WITH 1000-500 MB THICKNESSES IN THE
5500-5560M RANGE OVER THE NRN HALF OF THE COMMONWEALTH. THE BULK
OF THE PRECIP SHOULD FALL AS RAIN...WITH SOME GUSTY WEST WINDS AND
MAINLY MTN SNOW SHOWERS IN ITS WAKE FOR LATE NEXT WEEK.
FOR NOW WILL CONTINUE TO RIDE WITH A CHC OF EITHER SNOW/RAIN
ACROSS THE HIGHER TERRAIN OF THE NORTH WEDNESDAY...AND A CHC OF
PLAIN RAIN IN THE CENTRAL AND SRN VALLEYS.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
CIGS HAVE STEADILY LOWERED SINCE 06Z INTO MVFR AND IFR FLGT
CATS...AND EXPECT LOW CIGS TO PERSIST THRU THIS MORNING. PRIMARY
SFC LOW WILL LIFT NWD FM CMH INTO NW PA...WHILE SECONDARY LOW
DEVELOPS IN THE LEE OF THE APPLCHNS. SFC WNDS WILL SHIFT AROUND
FROM E/NE TO MORE OF A SLY COMPONENT BY THE LATE MORNING AND EARLY
AFTN...WITH CONDS GENERALLY IMPROVING TO MVFR. A STRONG COLD FRONT
WILL PLOW ACROSS ALL TERMINALS BTWN 18-00Z...ACCOMPANIED BY SCT TO
NMRS SHOWERS WITH PERHAPS A RUMBLE OF THUNDER POSSIBLE SRN SXNS.
POST-FRONTAL WESTERLY WIND GUSTS IN EXCESS OF 40KTS WILL BE
COMMON. THE STRONG DOWNSLOPE FLOW SHOULD YIELD MVFR TO VFR CIGS E
OF THE MTNS. IFR CONDS ARE EXPECTED OVR THE WESTERN HIGH TERRAIN
AIRFIELDS BFD-JST IN FQNT SNOW SHOWERS AND BLOWING SNOW.
OUTLOOK...
SAT...WINDY. IFR/SHSN WRN SXNS.
SUN...MVFR BCMG VFR WRN SXNS. NO SIG WX.
MON...VFR. SCHC OF MVFR -SHRA NRN TERMINALS.
TUE...VFR TO MVFR WITH -RA POSS LATE OVR WRN TERMINALS.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EST SATURDAY
FOR PAZ028-037-041-042-046-049>053-056>059-063>066.
WIND ADVISORY FROM 10 AM THIS MORNING TO 7 AM EST SATURDAY FOR
PAZ004>006-010>012-017>019-026-027-035-036-045.
HIGH WIND WARNING FROM 10 AM THIS MORNING TO 1 AM EST SATURDAY
FOR PAZ024-025-033-034.
WIND ADVISORY FROM 1 AM TO 7 AM EST SATURDAY FOR PAZ024-025-
033-034.
LAKE EFFECT SNOW ADVISORY FROM 7 PM THIS EVENING TO 4 PM EST
SATURDAY FOR PAZ004-005.
&&
$$
SYNOPSIS...LAMBERT/STEINBUGL
NEAR TERM...LAMBERT/STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...LAMBERT
AVIATION...STEINBUGL
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1120 AM CST FRI FEB 24 2012
.DISCUSSION...
ISSUED 1012 AM CST FRI FEB 24 2012
MAIN SURFACE BOUNDARY EXTENDS FROM NORTHEAST INDIANA THROUGH
WESTERN KENTUCKY LATE THIS MORNING...WHILE UPPER TROUGH LINGERS ABOUT
100 MILES WEST OF THERE. THERE WAS ABOUT 1-2 INCHES OF SNOW IN THE
FAR NORTHERN CWA FROM EARLIER...BUT MOST AREAS SOUTH OF THERE HAVE
SEEN THE SNOW MELTING AS IT HITS THE GROUND. LATEST RADAR IMAGERY
SHOWING PRECIPITATION IS NOW MORE SHOWERY...MOSTLY SNOW AT THE
MOMENT...BUT IN THE FORM OF RAIN SOUTH OF I-70. THE LATEST HRRR IS
MORE AGGRESSIVE THAN OTHER HIGH-RESOLUTION AND SYNOPTIC MODELS IN
LINGERING THE SHOWERS THROUGH THE DAY...BUT WITH THE UPPER TROUGH
NEARBY AND VERY COLD AIR ALOFT...FEEL THAT 30 POPS ARE STILL
WARRANTED THIS AFTERNOON.
HAVE SENT SOME UPDATED ZONES/GRIDS DUE TO THE LATEST PRECIPITATION
TRENDS. DID MAKE SOME MINOR ADJUSTMENTS TO THE TEMPERATURES...
WHICH LARGELY DID NOT AFFECT THE WORDED FORECASTS.
GEELHART
&&
.AVIATION...
ISSUED 1120 AM CST FRI FEB 24 2012
MVFR CEILINGS TO CONTINUE AT ALL TAF SITES EARLY THIS AFTERNOON.
SHOULD SEE AN UPWARD TREND IN CEILINGS THROUGH THE AFTERNOON...WITH
VISIBLE SATELLITE IMAGERY AND SURFACE OBS CURRENTLY SHOWING
CEILINGS RISING ABOVE 3000 FEET IN SOUTHEAST IOWA AND NORTHERN
MISSOURI...ADVANCING SOUTHEAST. HAVE BROUGHT KSPI/KDEC/KPIA INTO
VFR RANGE BY AROUND SUNSET...BUT HAVE LINGERED MVFR CONDITIONS
ELSEWHERE AS AN UPPER IMPULSE CURRENTLY IN MINNESOTA DROPS
SOUTHEAST. GUSTIEST WINDS EXPECTED THROUGH ABOUT 22-23Z WITH WINDS
DIMINISHING A BIT AFTERWARD...BUT THEY WILL STILL STAY ABOVE 10
KNOTS OVERNIGHT AS THE AFOREMENTIONED IMPULSE MOVES THROUGH. WHILE
SOME PERIODIC BREAKS IN THE CLOUDS WILL OCCUR AT TIMES...MORE
SUSTAINED CLEARING SHOULD TAKE PLACE LATE SATURDAY MORNING AS HIGH
PRESSURE BUILDS EAST OUT OF THE PLAINS.
GEELHART
&&
.PREV DISCUSSION...
ISSUED 255 AM CST FRI FEB 24 2012
SHORT TERM...TODAY THROUGH SUNDAY
BAND OF DEFORMATION ZONE SNOW CURRENTLY EXTENDING FROM THE CHICAGO
METRO AREA SOUTHWESTWARD TO MACOMB WILL GRADUALLY ROTATE E/NE AND
DISSIPATE AS THE MORNING PROGRESSES. BASED ON LATEST RADAR MOSAIC
AS WELL AS 00Z HIGH-RES MODELS...IT APPEARS MOST OF THE STEADY
LIGHT SNOW WILL IMPACT LOCATIONS ALONG AND NORTH OF A RUSHVILLE TO
BLOOMINGTON-NORMAL LINE THROUGH MIDDAY. AS SUCH...HAVE GONE WITH
CATEGORICAL POPS ACROSS THIS AREA THROUGH THE MORNING. ACCUMULATIONS
WILL REMAIN LIGHT...WITH PERHAPS AS MUCH AS 1 TO 2 INCHES ACROSS
FAR NORTHERN SECTIONS OF KNOX AND STARK COUNTIES. FURTHER
SOUTH...ANY PRECIP THAT OCCURS ACROSS THE REMAINDER OF CENTRAL AND
SOUTHEAST ILLINOIS WILL BE MUCH LIGHTER AND MORE SHOWERY IN
NATURE. HAVE THEREFORE ONLY INCLUDED CHANCE POPS ELSEWHERE. WITH
VERY COLD 500MB TEMPS OF AROUND -36C...MOST OF THE PRECIP WILL BE
IN THE FORM OF LIGHT SNOW-SHOWERS TODAY...HOWEVER SURFACE HIGH
TEMPS REACHING THE LOWER TO MIDDLE 40S ACROSS THE SOUTHEAST KILX
CWA WILL SUPPORT RAIN ALONG/SOUTH OF I-70. ASIDE FROM THE INTERMITTENT
LIGHT PRECIP...THE MAIN STORY TODAY WILL BE THE STRONG WESTERLY
WINDS. AS LOW PRESSURE DEEPENS TO THE EAST...TIGHTENING PRESSURE
GRADIENT WILL SUPPORT SUSTAINED WINDS IN THE 15 TO 25 MPH
RANGE...WITH GUSTS AS HIGH AS 35 MPH AT TIMES.
WINDS WILL DIMINISH AND SKIES WILL GRADUALLY CLEAR FROM WEST TO
EAST TONIGHT...AS HIGH PRESSURE BUILDS TOWARD THE MISSISSIPPI
RIVER VALLEY. OVERNIGHT LOWS WILL GENERALLY DROP INTO THE MIDDLE
TO UPPER 20S...BUT MAY SINK INTO THE UPPER TEENS ACROSS THE FAR
NORTHWEST CWA WHERE A LIGHT SNOW COVER WILL LIKELY EXIST. HIGH
PRESSURE WILL MOVE OVERHEAD ON SATURDAY...ENSURING A MOSTLY SUNNY
AND COOL DAY WITH SEASONABLE HIGHS IN THE UPPER 30S/LOWER 40S.
NEXT WEATHER-MAKER WILL BEGIN TO IMPACT CENTRAL ILLINOIS BY
SUNDAY...AS UPPER WAVE AND ASSOCIATED LOW PRESSURE TRACK ACROSS
THE NORTHERN PLAINS INTO THE UPPER MIDWEST. TIGHT PRESSURE
GRADIENT AHEAD OF THE SYSTEM WILL LEAD TO STRONG SOUTHERLY WINDS
GUSTING TO BETWEEN 30 AND 35 MPH. WITH AMPLE SUNSHINE AND STRONG
SOUTHERLY FLOW...AFTERNOON HIGH TEMPS WILL SOAR INTO THE 50S.
TRAILING COLD FRONT IS STILL EXPECTED TO SWING THROUGH THE AREA
SUNDAY NIGHT...HOWEVER SPRAWLING HIGH PRESSURE RIDGE WILL BLOCK
NORTHWARD TRANSPORT OF GULF MOISTURE. AS A RESULT...EXPECT A DRY
FROPA.
LONG TERM...MONDAY THROUGH THURSDAY
ACTIVE WEATHER PATTERN CONTINUES INTO THE EXTENDED...WITH THE NEXT
IN A SERIES OF UPPER WAVES APPROACHING BY TUESDAY/WEDNESDAY. 00Z
24 FEB GFS/ECMWF IN GOOD AGREEMENT CONCERNING TRACK/TIMING OF THIS
SYSTEM...WITH WARM ADVECTION CLOUDS AND PRECIP SPREADING INTO
ILLINOIS FROM THE WEST ON TUESDAY. ATMOSPHERE WILL BE WARM ENOUGH
TO SUPPORT ALL RAIN...AS HIGH TEMPS ARE EXPECTED TO CLIMB WELL
INTO THE 40S. NEGATIVELY TILTED UPPER TROUGH AND DEEPENING SURFACE
LOW WILL LIFT FROM THE CENTRAL PLAINS INTO THE WESTERN GREAT LAKES
BY EARLY WEDNESDAY...WITH TRAILING COLD FRONT PUSHING THROUGH
CENTRAL ILLINOIS. AMPLE DEEP MOISTURE AHEAD OF THE SYSTEM COUPLED
WITH POWERFUL UPPER DYNAMICS WILL BE ENOUGH TO TRIGGER SHOWERS AND
A FEW THUNDERSTORMS ACROSS THE AREA TUESDAY NIGHT. ONCE FRONT
PASSES...A FEW SHOWERS MAY LINGER INTO EARLY WEDNESDAY...BEFORE
COOLER/DRIER WEATHER ARRIVES BY THURSDAY.
BARNES
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1015 AM CST FRI FEB 24 2012
.DISCUSSION...
ISSUED 1012 AM CST FRI FEB 24 2012
MAIN SURFACE BOUNDARY EXTENDS FROM NORTHEEAST INDIANA THROUGH
WESTERN KENTUCKY LATE THIS MORNING...WHILE UPPER TROUGH LINGERS ABOUT
100 MILES WEST OF THERE. THERE WAS ABOUT 1-2 INCHES OF SNOW IN THE
FAR NORTHERN CWA FROM EARLIER...BUT MOST AREAS SOUTH OF THERE HAVE
SEEN THE SNOW MELTING AS IT HITS THE GROUND. LATEST RADAR IMAGERY
SHOWING PRECIPITATION IS NOW MORE SHOWERY...MOSTLY SNOW AT THE
MOMENT...BUT IN THE FORM OF RAIN SOUTH OF I-70. THE LATEST HRRR IS
MORE AGGRESSIVE THAN OTHER HIGH-RESOLUTION AND SYNOPTIC MODELS IN
LINGERING THE SHOWERS THROUGH THE DAY...BUT WITH THE UPPER TROUGH
NEARBY AND VERY COLD AIR ALOFT...FEEL THAT 30 POPS ARE STILL
WARRANTED THIS AFTERNOON.
HAVE SENT SOME UPDATED ZONES/GRIDS DUE TO THE LATEST PRECIPITATION
TRENDS. DID MAKE SOME MINOR ADJUSTMENTS TO THE TEMPERATURES...
WHICH LARGELY DID NOT AFFECT THE WORDED FORECASTS.
GEELHART
&&
.AVIATION...
ISSUED 548 AM CST FRI FEB 24 2012...FOR THE 12Z TAFS
LIGHT SNOW WILL HIT PIA AND BMI THE HARDEST...WITH MVFR VIS IN
SNOW SHOWERS THIS MORNING. SO TRAVEL SURFACES THERE WILL HAVE THE
BEST CHANCES OF BECOMING SLIPPERY FROM SNOW. IFR CLOUD HEIGHTS
WILL LIKELY REMAIN THROUGH AROUND 15Z AT PIA AND POSSIBLY AN HOUR
OR TWO LONGER AT BMI.
SNOWFALL AND VIS WILL IMPROVE TO VFR AFTER 15Z...WITH ONLY LIGHT
SNOW OR FLURRIES LINGERING INTO THE AFTERNOON.
STRONG NORTHWEST WINDS WILL BE THE OTHER MAJOR WEATHER FEATURE
TODAY. WIND GUSTS BETWEEN 30-35KT ARE LIKELY FOR MUCH OF THE DAY.
WIND GUSTS WILL BECOME LESS STRONG TONIGHT...BUT SUSTAINED WINDS
MAY REMAIN 15-20 KT.
MVFR CLOUDS ARE EXPECTED TO LINGER OVERNIGHT. SOME CLEARING WILL
BE POSSIBLE IN THE WEST FOR PIA/SPI LATER TONIGHT. HOWEVER...
CONFIDENCE IS LOW ON THE EXTENT OF ANY CLEARING...SO IT WAS LEFT
OUT OF THIS TAF ISSUANCE.
SHIMON
&&
.PREV DISCUSSION...
ISSUED 255 AM CST FRI FEB 24 2012
SHORT TERM...TODAY THROUGH SUNDAY
BAND OF DEFORMATION ZONE SNOW CURRENTLY EXTENDING FROM THE CHICAGO
METRO AREA SOUTHWESTWARD TO MACOMB WILL GRADUALLY ROTATE E/NE AND
DISSIPATE AS THE MORNING PROGRESSES. BASED ON LATEST RADAR MOSAIC
AS WELL AS 00Z HIGH-RES MODELS...IT APPEARS MOST OF THE STEADY
LIGHT SNOW WILL IMPACT LOCATIONS ALONG AND NORTH OF A RUSHVILLE TO
BLOOMINGTON-NORMAL LINE THROUGH MIDDAY. AS SUCH...HAVE GONE WITH
CATEGORICAL POPS ACROSS THIS AREA THROUGH THE MORNING. ACCUMULATIONS
WILL REMAIN LIGHT...WITH PERHAPS AS MUCH AS 1 TO 2 INCHES ACROSS
FAR NORTHERN SECTIONS OF KNOX AND STARK COUNTIES. FURTHER
SOUTH...ANY PRECIP THAT OCCURS ACROSS THE REMAINDER OF CENTRAL AND
SOUTHEAST ILLINOIS WILL BE MUCH LIGHTER AND MORE SHOWERY IN
NATURE. HAVE THEREFORE ONLY INCLUDED CHANCE POPS ELSEWHERE. WITH
VERY COLD 500MB TEMPS OF AROUND -36C...MOST OF THE PRECIP WILL BE
IN THE FORM OF LIGHT SNOW-SHOWERS TODAY...HOWEVER SURFACE HIGH
TEMPS REACHING THE LOWER TO MIDDLE 40S ACROSS THE SOUTHEAST KILX
CWA WILL SUPPORT RAIN ALONG/SOUTH OF I-70. ASIDE FROM THE INTERMITTENT
LIGHT PRECIP...THE MAIN STORY TODAY WILL BE THE STRONG WESTERLY
WINDS. AS LOW PRESSURE DEEPENS TO THE EAST...TIGHTENING PRESSURE
GRADIENT WILL SUPPORT SUSTAINED WINDS IN THE 15 TO 25 MPH
RANGE...WITH GUSTS AS HIGH AS 35 MPH AT TIMES.
WINDS WILL DIMINISH AND SKIES WILL GRADUALLY CLEAR FROM WEST TO
EAST TONIGHT...AS HIGH PRESSURE BUILDS TOWARD THE MISSISSIPPI
RIVER VALLEY. OVERNIGHT LOWS WILL GENERALLY DROP INTO THE MIDDLE
TO UPPER 20S...BUT MAY SINK INTO THE UPPER TEENS ACROSS THE FAR
NORTHWEST CWA WHERE A LIGHT SNOW COVER WILL LIKELY EXIST. HIGH
PRESSURE WILL MOVE OVERHEAD ON SATURDAY...ENSURING A MOSTLY SUNNY
AND COOL DAY WITH SEASONABLE HIGHS IN THE UPPER 30S/LOWER 40S.
NEXT WEATHER-MAKER WILL BEGIN TO IMPACT CENTRAL ILLINOIS BY
SUNDAY...AS UPPER WAVE AND ASSOCIATED LOW PRESSURE TRACK ACROSS
THE NORTHERN PLAINS INTO THE UPPER MIDWEST. TIGHT PRESSURE
GRADIENT AHEAD OF THE SYSTEM WILL LEAD TO STRONG SOUTHERLY WINDS
GUSTING TO BETWEEN 30 AND 35 MPH. WITH AMPLE SUNSHINE AND STRONG
SOUTHERLY FLOW...AFTERNOON HIGH TEMPS WILL SOAR INTO THE 50S.
TRAILING COLD FRONT IS STILL EXPECTED TO SWING THROUGH THE AREA
SUNDAY NIGHT...HOWEVER SPRAWLING HIGH PRESSURE RIDGE WILL BLOCK
NORTHWARD TRANSPORT OF GULF MOISTURE. AS A RESULT...EXPECT A DRY
FROPA.
LONG TERM...MONDAY THROUGH THURSDAY
ACTIVE WEATHER PATTERN CONTINUES INTO THE EXTENDED...WITH THE NEXT
IN A SERIES OF UPPER WAVES APPROACHING BY TUESDAY/WEDNESDAY. 00Z
24 FEB GFS/ECMWF IN GOOD AGREEMENT CONCERNING TRACK/TIMING OF THIS
SYSTEM...WITH WARM ADVECTION CLOUDS AND PRECIP SPREADING INTO
ILLINOIS FROM THE WEST ON TUESDAY. ATMOSPHERE WILL BE WARM ENOUGH
TO SUPPORT ALL RAIN...AS HIGH TEMPS ARE EXPECTED TO CLIMB WELL
INTO THE 40S. NEGATIVELY TILTED UPPER TROUGH AND DEEPENING SURFACE
LOW WILL LIFT FROM THE CENTRAL PLAINS INTO THE WESTERN GREAT LAKES
BY EARLY WEDNESDAY...WITH TRAILING COLD FRONT PUSHING THROUGH
CENTRAL ILLINOIS. AMPLE DEEP MOISTURE AHEAD OF THE SYSTEM COUPLED
WITH POWERFUL UPPER DYNAMICS WILL BE ENOUGH TO TRIGGER SHOWERS AND
A FEW THUNDERSTORMS ACROSS THE AREA TUESDAY NIGHT. ONCE FRONT
PASSES...A FEW SHOWERS MAY LINGER INTO EARLY WEDNESDAY...BEFORE
COOLER/DRIER WEATHER ARRIVES BY THURSDAY.
BARNES
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1159 AM CST FRI FEB 24 2012
.AVIATION...
COUPLE OF UPPER LEVEL DISTURBANCES UPSTREAM... ONE OVER SOUTHERN MN
AND A SECOND DROPPING INTO NW MN ATTIM ... WILL KEEP LOW CLOUDS
AROUND THROUGH AT LEAST FIRST HALF OF TNGT WITH HIGHLY VARIABLE CIGS
FROM MVFR (1500-2000 FT AGL) TO VFR (4000-6000+ FT AGL). FEW-SCT
SHSN EXPECTED AROUND THE AREA THROUGH EARLY EVE... WHICH COULD
BRIEFLY REDUCE VSBYS TO 1-5SM. MAY SEE CLOUDS SCATTERING OUT BY LATE
EVE AND OVRNGT WITH VFR CONDITIONS BUT SOME LINGERING BASES AT
MVFR LEVELS... AS UPPER LEVEL DISTURBANCES PASS BY AND SUBSIDENCE
INCREASES. WINDS BRISK THROUGH EARLY EVE AT 15-30 KTS FROM W/NW WILL
DIMINISH TO AROUND 10-15 KTS OVRNGT THROUGH 18Z SAT.
&&
.PREV DISCUSSION... /ISSUED 317 AM CST FRI FEB 24 2012/
SYNOPSIS...
06Z SFC ANALYSIS HAS A LOW NEAR KDNV WITH THE MAIN SYNOPTIC LOW
SOUTHEAST OF KCEZ BUT STILL WEST OF CINCINNATI. A SUGGESTED MESO LOW
WAS SOUTH OF KVYS BUT EAST OF KC75 ALONG THE ILLINOIS RIVER. AN
INVERTED TROF RAN NORTHWEST FROM THE MESO LOW INTO WESTERN WISCONSIN
WHILE A SECONDARY TROF RAN FROM THE LOW WEST INTO NORTHERN MISSOURI.
DEW POINTS WERE IN THE 20S AND 30S ACROSS MUCH OF THE MIDWEST WITH
40S AND HIGHER IN THE OHIO VALLEY AND DEEP SOUTH. RADAR TRENDS SHOW
THE DEFORMATION ZONE MOVING EAST ACROSS THE AREA.
SHORT TERM...TODAY AND TONIGHT...
THE IMMEDIATE CONCERN IS WHAT TO DO WITH CURRENT HEADLINES.
OVERALL...TRENDS FROM THE RUC ARE QUITE USEFUL IN DEPICTING THE
CURRENT WX. A COMBINATION OF THE HEAVY RAIN TOOL WITH OVERALL
FORCING/CONDENSATION PRESSURE DEFICITS INDICATES THAT SNOW WILL
STILL BE ONGOING ACROSS THE EASTERN CWFA AT 12Z IN THE DEFORMATION
ZONE. AS SUCH...THE CURRENT HEADLINES WILL BE EXTENDED FOR 1-2 HRS
FOR HENRY...WHITESIDE...BUREAU...AND PUTNAM COUNTIES IN ILLINOIS.
AFT 14Z...RUC TRENDS SHOW THE OVERALL FORCING FALLING APART WITH
CONDENSATION PRESSURE DEFICITS RISING A LITTLE. HOWEVER...THE
OVERALL ATMOSPHERE REMAINS SATURATED SO WHILE THE INTENSITY OF THE
SNOW WILL LET UP TO POSSIBLY ONLY FLURRIES...-SN SHOULD CONTINUE
DURING THE MORNING HOURS.
BY LATE MORNING AND CONTINUING INTO THE AFTERNOON LOW LEVEL LAPSE
RATES BECOME VERY STEEP. THE RUC ALONG WITH OTHER MODELS SHOW A
RESPECTABLE VORT MAX ROTATING THROUGH THE AREA WHICH SHOULD INDUCE
SHSN FROM LATE MORNING THROUGH THE AFTERNOON HOURS. THE STEEP LAPSE
RATES WILL ALSO ALLOW HIGHER MOMENTUM AIR TO MIX DOWN RESULTING IN
BRISK IF NOT WINDY CONDITIONS.
ADDITIONAL SNOW ACCUMULATIONS AFTER 12Z SHOULD BE GENERALLY ONE HALF
INCH OR LESS.
TONIGHT...LOW LEVEL LAPSE RATES REMAIN QUITE STEEP WITH NO
STABILIZATION OCCURRING UNTIL ROUGHLY SUNRISE. ADD INTO THIS
CHANNELED VORTICITY WITH SOME CYCLONIC FLOW ACROSS THE AREA AND
CLOUDS MAY BE SLOW TO BREAK UP OR CLEAR OUT. THEREFORE...WILL HOLD
ONTO THE CLOUDS LONGER. ADDITIONALLY...SINCE SUNSET IS NOW CLOSER TO
6 PM THERE MAY BE SOME LINGERING FLURRIES OR DECAYING SHSN INTO THE
EARLY EVENING ACROSS THE EASTERN CWFA.
08..
LONG TERM...
AN ACTIVE WEATHER REGIME WILL BE IN PLACE THROUGH THE LONG TERM
FORECAST. MODELS ARE IN AGREEMENT WITH A POTENT S/W PASSING TO OUR
NORTH LATE IN THE WEEKEND WITH A SIGNIFICANT TROF MOVING THROUGH
MID-WEEK.
FOR SATURDAY AND SATURDAY NIGHT...A HIGH PRESSURE RIDGE WILL BE OVER
THE AREA EARLY SATURDAY. THE RIDGE IS PUSHED EAST BY SATURDAY
EVENING AS S/W ENERGY MOVES OUT OF THE PAC NW INTO THE NORTHERN
PLAINS...DRIVING A SURFACE LOW INTO THE EASTERN DAKOTAS BY SUNDAY
MORNING. EXPECT DRY CONDITIONS DURING THE PERIOD SO TEMPERATURES
WILL BE THE MAIN CONCERN. LIMITED MIXING IN THE RIDGE AXIS
SATURDAY WILL LIMIT HIGHS. THERE MAY ALSO BE SOME RESIDUAL SNOW
COVER NORTH FROM THE CURRENT EVENT...SO WILL KEEP HIGHS IN THE
30S. MINS SATURDAY NIGHT WILL LIKELY OCCUR DURING THE EVENING AS
SOUTHERLY FLOW BEGINS INCREASING AHEAD OF THE NORTHERN PLAINS
SURFACE LOW. KEPT MINS AROUND 20 IN THE NORTHEAST WHERE BEST
COOLING POTENTIAL EXISTS WITH LIGHT WINDS IN THE EVENING AND
POSSIBLY SOME SNOW STILL ON THE GROUND. LOWS IN THE SOUTHWEST
SHOULD OCCUR FAIRLY EARLY IN THE EVENING...SO KEPT THAT AREA IN THE
LOW 30S. TEMPS SHOULD STEADY OUT OR RISE SOME DURING THE LATE
EVENING AND OVERNIGHT HOURS.
SUNDAY AND SUNDAY NIGHT THE NORTHERN PLAINS S/W AND SURFACE LOW
WILL CROSS MN AND MOVE INTO THE GREAT LAKES BY MONDAY MORNING. A
COLD FRONT BEHIND THE SYSTEM WILL DROP SOUTHEAST THROUGH THE
FORECAST AREA SUNDAY NIGHT. WITH LIMITED MOISTURE AND THE BEST
FORCING STAYING WELL NORTH OF THE CWFA...HAVE REMOVED THE LOW POPS
FROM THE NORTH. HIGHS IN THE 40S NORTH TO MID 50S FAR SOUTH LOOK
REASONABLE WITH THE FORECAST AREA IN THE WARM SECTOR SUNDAY...AND
GUSTY SOUTHWEST WINDS TO AID DEEP MIXING. THE COLD FRONT WILL MOVE
THROUGH SUNDAY NIGHT...BUT THE AIR BEHIND THE FRONT IS NOT THAT
COLD...SO KEPT MINS IN THE MID 20S TO LOW 30S.
THE NEXT SYSTEM TO IMPACT THE AREA IS A SIGNIFICANT TROF THAT IS
EXPECTED TO MOVE INTO THE CA COAST MONDAY AND HEAD EAST INTO THE
PLAINS BY TUESDAY EVENING. THE MODELS WERE COMING INTO DECENT
AGREEMENT ON THE 24/00Z RUN WITH THIS SYSTEM TAKING A MORE
NORTHERN TRACK...LIFTING THE SURFACE LOW THROUGH NW IA TUESDAY
NIGHT AND INTO THE GREAT LAKES BY LATE WEDNESDAY. WITH GOOD
AGREEMENT AMONG THE LONG RANGE MODELS THE BLENDED GUIDANCE HAS
WARMED TEMPERATURES UP CONSIDERABLY MONDAY NIGHT THROUGH
WEDNESDAY. HAVE EVEN BUMPED UP TEMPERATURES A FEW DEGREES FROM
GUIDANCE MONDAY NIGHT AND TUESDAY WHEN IT APPEARS WE WILL BE IN
THE WARM SECTOR. THE SYSTEM SHOULD HAVE SOME GULF MOISTURE TO WORK
WITH AS IT MOVES THROUGH THE MID MS VALLEY SO MAINTAINED HIGH
CHANCE OR LIKELY POPS TUESDAY INTO WEDNESDAY. SOME THUNDERSTORMS
CANNOT BE RULED OUT FOR TUESDAY NIGHT WHEN THE BEST FORCING WILL
LIFT THROUGH THE AREA. HOWEVER...I DID NOT MENTION ANY THUNDER
YET...SINCE THERE IS STILL POTENTIAL FOR THE MODEL SOLUTIONS TO
VARY. STRONG WEST TO NORTHWEST WINDS WILL USHER IN COLDER AIR LATE
TUESDAY NIGHT AND WEDNESDAY AS THE OCCLUDED SYSTEM LIFTS NORTHEAST
THROUGH WI AND INTO THE GREAT LAKES. WITH THE COLD AIR MOVING BACK
IN ANY LINGERING PRECIP WILL MIX WITH OR CHANGE TO SNOW. BY
THURSDAY TEMPERATURES SHOULD BE BACK TO NEAR NORMAL. ..DLF..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION...UPDATED
NWS DES MOINES IA
1139 AM CST FRI FEB 24 2012
...UPDATED AVIATION DISCUSSION...
.SHORT TERM /TODAY/...
ACCUMULATING SNOW QUICKLY DIMINISHING AS SURFACE LOW CONTINUES TO
PULL EAST THIS MORNING. MAIN CONCERN TODAY IS WITH WINDS AND
POTENTIAL FOR SNOW SHOWERS. CAA WILL CONTINUE TO INCREASE THROUGHOUT
THE DAY WITH PRESSURE GRADIENT AND SOME MIXING. MIXING WILL BE
SOMEWHAT LIMITED TO THE STRATUS DECK HOLDING STRONG THROUGH THE DAY.
WINDS ATOP THE MIXED LAYER NEARING 40KTS BY LATE THIS
AFTERNOON...BUT THINKING THE RUC IS A LITTLE OVERDONE AND LEANED
TOWARD THE SREF/NAM FOR WINDS. THE 925-850MB RH PERSISTS TODAY AND
IS WELL WITHIN THE SNOW GROWTH ZONE...ESPECIALLY OVER THE EASTERN
AND NORTHERN SECTIONS OF THE FORECAST AREA. KEPT WITH MENTION OF
SNOW SHOWERS TODAY AND LIGHT ACCUMULATIONS...MAY SEE A HALF INCH
FROM THE ALO TO MCW AREA. NOT ANTICIPATING TEMPS TO RISE ALL THAT
MUCH TODAY WITH THE CAA...STRATUS DECK...AND FRESH SNOW PACK. SO
WENT SLIGHTLY BELOW GUIDANCE FOR MAX TEMPS TODAY.
.LONG TERM /TONIGHT THROUGH THURSDAY/...
TWO SIGNIFICANT SYSTEMS TO CONTEND WITH THROUGH THIS
PERIOD...PRECEDED BY VERY MINOR WAVE TONIGHT. THE LATTER IS
EXPECTED TO CROSS THE NRN ROCKIES INTO THE LOWER MO RIVER VALLEY BY
THIS AFTERNOON AND THIS EVENING. WAVE IS CURRENTLY GENERATING SOME
LIGHT SNOW OR FLURRIES ACROSS MT/ND SO HAVE ADDED TRACE WORDING SW
DURING THE EVENING TO ACCOUNT FOR THIS. MODEL REFLECTION OF THIS
SYSTEM QUITE VARIABLE WITH GEM REGIONAL AND GLOBAL MOST
AGGRESSIVE...WHILE THE ECMWF AND DOMESTIC MODELS ARE WEAKER. ANY
FORCING IS VERY COMPACT HOWEVER SO DAY SHIFT WILL HAVE TO EXAMINE
WHETHER STRENGTH IS SUFFICIENT TO WARRANT MEASURABLE MENTION AND IF
SO WHETHER IT CLIPS US OR STAYS JUST TO THE SOUTH AND WEST.
NEXT SYSTEM CURRENTLY OFF THE PACIFIC NW COAST WILL CROSS THE
ROCKIES SAT BEFORE AMPLIFYING AS IT ENTERS THE MID MO VALLEY.
FORCING...BOTH KINEMATIC AND THERMODYNAMIC...IS QUITE IMPRESSIVE
WITH THIS SYSTEM SAT NIGHT BUT MOISTURE BELOW 2.5KM IS SPARSE. BY
SUN AIRMASS REMAINS DRY WITH DOWNWARD MOTION QUICKLY SURGING IN
BEHIND SHARP QG FORCING COUPLET SO HAVE REMOVED NRN POPS ON SUN.
CONSIDERING THE STRENGTH OF THE LIFT SAT NIGHT THAT MAY BE A BETTER
POTENTIAL PRECIP WINDOW AND MAY NEED TO ADD TRACE AMOUNTS AT SOME
POINT IF MOISTURE CAN INCREASE SLIGHTLY.
NEXT SYSTEM WHICH IS EVEN STRONGER WITH SIMILAR BUT SLIGHTLY MORE
SOUTHERLY PATH WILL ENTER MO VALLEY LATE TUE. 00Z GFS/ECMWF ARE NOW
IN QUITE GOOD AGREEMENT TRACKING DEEP SURFACE LOW ACROSS NWRN IA TUE
EVENING. ALTHOUGH POTENT SNOW STORM MAY AFFECT DAKOTAS AND
MN...THIS PATH WILL KEEP IA MAINLY IN THE WARM SECTOR WHICH HAS
RESULTED IN WARMER TEMP FORECAST MON INTO TUE...ALONG WITH FURTHER
NUDGING UPWARD OF POPS. OVERALL FORCING WILL GRADUALLY INCREASE MON
NIGHT WITH SNOW POSSIBLE THEN INCREASE FURTHER TUE AND TUE NIGHT
WITH TRANSITION TO RAIN SHOWERS. HAVE ALSO ADDED ISOLATED THUNDER
CONSIDERING OVERALL STRENGTH OF LIFT ALONG WITH SHOWALTERS HOVERING
AROUND ZERO AND K INDICES WELL INTO THE 20S AND LOWER 30S. AS
SYSTEM PULLS AWAY WINDS WILL BECOME THE PRIMARY FEATURE FOR IA.
MODEL CONSENSUS SUGGESTS SUSTAINED SPEEDS ABOVE 20KTS SOUTH AND WEST
BY MIDDAY WED WITH GUSTS AT HIGH AS 35-40KTS.
&&
.AVIATION...24/18Z
OVERNIGHT/MORNING MVFR CIGS HAVE LARGELY CLEARED OUT TO THE
EAST...BUT MAY LINGER IN MCW AT TIMES OVER THE NEXT FEW HRS.
MEANWHILE ANOTHER LARGE AREA OF LOW CLOUDS IS APPROACHING FROM SDAK
AND WILL REACH THE TERMINALS BTWN ABT 21Z AND 00Z THIS EVE. WITHIN
THIS CLOUD DECK CIGS ARE HIGHLY VARIABLE BTWN FL020 AND FL060 WITH
SCT -SHSN DROPPING VSBYS TO ANYWHERE BTWN 1SM AND 5SM. GIVEN THIS
VARIABILITY BUT FAIRLY WIDE COVERAGE OF SUCH CONDITIONS HAVE
INCLUDED TEMPOS AT MOST OF THE TERMINALS TO ACCOUNT FOR BOUNCING
CIGS/VSBYS THIS EVE. HOWEVER...NO CIGS IFR OR LOWER ARE EXPECTED ANY
ANY VSBYS BLO 3SM WILL BE VERY LOCALIZED AND BRIEF. CONDITIONS WILL
IMPROVE TONIGHT AS HIGH PRESSURE MOVES IN...WITH VFR CONDITIONS
PREVAILING BY SAT MORN.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...KLP
LONG TERM...BSS
AVIATION...LEE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
118 PM EST FRI FEB 24 2012
.UPDATE...
ISSUED AT 1126 AM EST FRI FEB 24 2012
SNOW OVER NORTH CENTRAL HAS INCREASED WITHIN LAST HOUR WITH
NORTHERLY WINDS OFF LK SUPERIOR AND SOME HELP FROM FRINGE OF SYSTEM
MOVING BY TO THE SOUTHEAST. VIS SATELLITE INDICATES MID CLOUDS
STREAMING NORTH WHILE OVR FLOW OVR LK SUPERIOR IS MORE NORTHERLY.
INVERSION TOP IS AROUND 5-7KFT PER VWP AND TEMPS AT TOP OF INVERSION
ARE AROUND -12C. GIVEN THE ADDED SYNOPTIC SUPPORT THIS IS SEEMING
GOOD ENOUGH FOR LAKE ENHANCEMENT. SNOW AMOUNTS SO FAR ARE AROUND A
HALF INCH...BUT IT REALLY HAS BEEN ONLY SNOWING FOR HALF HOUR. 1.5
DEGREE REFLECTIVITY OF KMQT RADAR INDICATES HIGHER REFLECTIVITIES
NORTH OF BIG BAY ARE SHRINKING TOWARD MARQUETTE COUNTY SHORE...SO
UPTICK IN SNOW MAY SETTLE BACK DOWN IN NEXT HOUR OR TWO. NORTH WINDS
SHOULD CONTINUE REST OF THE AFTN SO HAVE INCREASED POPS FOR
MARQUETTE/ALGER. BUMPED UP SNOW AMOUNTS TO 2-4 INCHES FOR REST OF
DAY. OUT WEST...KDLH RADAR INDICATES THAT HEAVIER BANDS OF LK EFFECT
ARE ABOUT TO BEGIN TO MOVE INTO WESTERN CWA. ADVY APPEARS GOOD THERE
ATTM. A BIT CONCERNED THAT BASED ON FCST CONVERGENCE FM HIGHER
RESOLUTION 12Z MODELS...THAT EVENTUALLY FAR NORTHERN GOGEBIC AND MUCH
OF NORTHERN ONTONAGON COULD GET INTO PERIOD OF HEAVIER SNOW LATE AFTN
THROUGH TONIGHT AND MAY NEED AN EVENTUAL WARNING. WILL CONTINUE TO
EVALUATE THIS DURING AFTN ONCE THE SNOW SETS UP OVR THE FAR WEST.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 521 AM EST FRI FEB 24 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A TROF OVER THE CNTRL
CONUS. A VIGOROUS LOOKING SHORTWAVE TRACKING E INTO IL WAS
SUPPORTING A BAND OF SNOW FROM ERN IA ACROSS SRN WI/NRN IL INTO LWR
MI. UPSTREAM....A SHORTWAVE TROF EXTENDS FROM SRN MANITOBA THRU THE
ERN DAKOTAS/WRN MN WITH VORT MAX APPARENT OVER SE MANITOBA. AT THE
SFC...OBS INDICATE ASSOCIATED WEAK SFC LOW N OF KINL WITH TROF
EXTENDING SE TOWARD WRN LAKE SUPERIOR...AND KDLH RADAR SHOWS A BAND
OF -SN ALONG THE TROF. CLOSER TO HOME...MOISTURE EXTENDING TO AROUND
6KFT PER FCST SOUNDINGS AND IMPLIED BY KMQT VAD WIND PROFILE ALONG
WITH 850MB TEMPS OF -9/-10C IS SUPPORTING FLURRIES/-SHSN OFF LAKE
SUPERIOR INTO NCNTRL UPPER MI. -SHSN TRENDS OVERNIGHT HAVE BEEN ODD
WITH UNORGANIZED SNOW AREAS DEVELOPING AND INTENSIFYING OVER THE
WATER ONLY TO PERSIST FOR A WHILE AND THEN RAPIDLY WEAKEN. SHORT
TERM FCST CONCERNS WILL REVOLVE AROUND SHORTWAVE TO THE NW...AND THE
AFFECTS IT WILL HAVE ON LAKE EFFECT LATER TODAY THRU TONIGHT.
00Z CWPL SOUNDING PROBABLY GIVES A DECENT REPRESENTATION OF AIR MASS
THAT WILL BE OVER THE WRN FCST AREA LATER TODAY/TONIGHT. IF SO...
850MB TEMPS WILL DROP A COUPLE OF DEGREES C AND COLUMN MOISTURE WILL
DEEPEN SIGNIFICANTLY. MODEL GUIDANCE IS IN GOOD AGREEMENT ON THIS
COOLING/MOISTENING. AT THE SAME...TIME WEAK DEEP LAYER FORCING WILL
OVERSPREAD WRN LAKE SUPERIOR/WRN UPPER MI IN ASSOCIATION WITH
AFOREMENTIONED SHORTWAVE TO THE NW. AT THE LOW LEVELS...THERE IS
GOOD AGREEMENT AMONG NUMEROUS MODELS THAT APPROACHING SFC TROF WILL
BASICALLY HANG UP OVER WRN LAKE SUPERIOR THIS AFTN (ESPECIALLY LATE)
AND TONIGHT FROM THE MN ARROWHEAD TO GOGEBIC/ONTONAGON COUNTIES. THE
RESULTING SHARP CONVERGENCE SHOULD REALLY AID LAKE ENHANCEMENT
POTENTIAL. WITH SNOW RATIOS OVERALL PROBABLY A LITTLE UNDER 20:1...
EVENT SHOULD EASILY EXCEED LOWER RATIO ADVY CRITERIA SNOWFALL (3
INCHES OR MORE IN 12HRS) WHERE LOW-LEVEL CONVERGENCE IS MAXIMIZED...
PROBABLY IN A FAIRLY SMALL AREA FROM KIWD TO WAKEFIELD...BERGLAND
AND WHITE PINE. PLAN TO RUN ADVY FOR ONTONAGON/GOGEBIC FROM 21Z
TODAY TO 15Z SAT FOR TOTAL SNOW ACCUMULATION OF 5-9 INCHES. EMPHASIS
WILL BE ON THE AREA MENTIONED. WITH SOME LES ALEADY NOTED OVER WRN
LAKE SUPERIOR ON KDLH RADAR AND A DECENT BAND OF SYNOPTIC SNOW
ASSOCIATED WITH APPROACHING SFC TROF...IT`S NOT OUT OF THE QUESTION
THAT SNOWFALL COULD BECOME QUITE A BIT HEAVIER THAN CURRENTLY
ANTICIPATED. WILL NEED TO WATCH MORNING/AFTN TRENDS FOR POTENTIAL
UPGRADE TO WARNING. ELSEWHERE ALONG LAKE SUPERIOR...SLIGHT COOLING
OF AIR MASS AND STRENGTHENING NORTHERLY WINDS WILL LEAD TO AN
INCREASE IN LES THIS AFTN INTO TONIGHT. ACCUMULATIONS WILL BE
LIGHTER THAN OVER THE FAR W DUE TO LESS INFLUENCE FROM SHORTWAVE...
SHALLOWER MOISTURE AND WEAKER LOW-LEVEL CONVERGENCE. WITH LONGER
FETCH AND MORE FAVORABLE WIND DIRECTION...SOME LOCATIONS FROM ERN
MARQUETTE COUNTY INTO ALGER COUNTY MAY SEE A FEW INCHES OF SNOW THRU
SAT MORNING.
DRIER AIR...LOWERING INVERSION AND INCREASINGLY ANTICYCLONIC FLOW AS
WINDS BACK WILL LEAD TO DIMINISHING LES SAT. WITH 850MB TEMPS AROUND
-14C...PROBABLY WON`T SEE LES COMPLETELY END SAT AFTN.
ANY LINGERING LES/FLURRIES WILL END SAT EVENING AS SFC HIGH PRES
RIDGE SHIFTS ACROSS THE AREA. MIGHT BE A WINDOW FOR TEMPS TO PLUMMET
BEFORE HIGH CLOUDS INCREASE/THICKEN FROM W TO E DURING THE NIGHT.
BEST OPPORTUNITY WOULD PROBABLY BE OVER THE CNTRL DUE TO LONGER
PERIOD BTWN DEPARTURE OF LAKE STRATOCU AND INCREASE OF HIGH CLOUDS.
.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 521 AM EST FRI FEB 24 2012
A 500MB SHORTWAVE TROUGH CURRENTLY OVER THE PACIFIC NW CONUS WILL
HAVE MOVED INTO THE NRN PLAINS BY THE START OF THE PERIOD 12Z
SUN...SPINNING UP A SFC LOW AS IT MOVED LEEWARD OF THE ROCKIES. THE
SFC LOW IS DEPICTED BY MODELS TO BE OVER ERN SD AT 12Z SUN. MODELS
STILL VARY IN THE INTENSITY OF THE SYSTEM AT THIS POINT...AND
THROUGH THE TIME THE SYSTEM PASSES OVER THE CWA. THE 12Z/23 ECMWF
AND 00Z/24 GEM ARE ON THE STRONGER SIDE OF GUIDANCE WITH THE SFC LOW
AROUND 996MB AT 12Z SUN...WHILE THE 00Z/24 GFS AND 00Z/24 NAM SHOW THE
SFC LOW AT 1002MB. ASSIDE FROM SYSTEM STRENGTH...MODELS ARE IN GOOD
AGREEMENT ON THE TRACK AND FAIR AGREEMENT ON THE SPEED OF THE
SYSTEM...WITH THE DEEPER ECMWF AND GEM BEING ON THE SLOW SIDE OF
GUIDANCE. USED A CONSENSUS OF THE MODELS FOR THE SPEED OF THE
SYSTEM...WHICH IS WEAKENING AS THE SHORTWAVE GETS SHEARED APART WITH
EASTWARD MOVEMENT.
WITH THAT IN MIND...THE SFC LOW /AND UPPER SHORTWAVE OVER OR JUST N
OF THE SFC LOW/ MOVES TO NEAR IRONWOOD BY 00Z MON. THE SFC LOW THEN
MOVES ACROSS UPPER MI...BEFORE MOVING TO THE FAR ERN CWA BY 12Z MON.
THIS TRACK CONFINES THE HEAVIEST SNOW /AND IT IS EXPECTED TO BE ALL
SNOW/ TO FAR NRN UPPER MI AND LAKE SUPERIOR. SYNOPTIC SNOW LOOKS TO
BE JUST MOVING INTO THE WRN CWA AROUND 12Z SUN...COVERING ROUGHLY
THE WRN HALF OF UPPER MI BY 18Z. THERE IS THE POSSIBILITY FOR SOME
LES OVER ERN UPPER MI IN THE ANTICYCLONIC FLOW AND 850MB TEMPS
AROUND -12C AHEAD OF THE SYSTEM...BUT WILL KEEP THAT AT CHANCE POPS
FOR NOW. IT THEN LOOKS LIKE A DRY SLOT WILL ROTATE IN...ESPECIALLY
OVER THE SRN CWA. THE GFS CRANKS OUT AROUND 0.4 INCHES OF QPF OVER
MUCH OF UPPER MI THROUGH 12Z MON...BEFORE THE SYSTEM MOVES OUT AND
LES STARTS. THE NAM SHOWS CLOSER TO 0.5 INCHES OVER MUCH OF THE
AREA. THE ECMWF SHOWS AROUND 0.4 INCHES OF QPF OVER THE KEWEENAW
PENINSULA AND LAKE SUPERIOR...WITH AROUND 0.2 INCHES OVER ALL BUT
SRN MENOMINEE COUNTY WHERE IT SHOWS LESS THAN 0.1 INCHES. THE GEM IS
VERY CLOSE TO THE GFS SOLUTION FOR QPF. THERE ARE SIGNALS THAT
INDICATE WE MAY GET A HEAVIER BAND OF SNOW ALONG THE WARM FRONT THAT
SURGES NORTHWARD LATE SUNDAY...WHICH WOULD FAVOR AREAS OF S CENTRAL
AND ERN UPPER MI TO GET SOME HEAVIER SNOW. WILL NOT PUT THIS DETAIL
INTO THE GRIDS JUST YET SINCE THERE IS STILL SOME UNCERTAINTY IN THE
TRACK/TIMING OF THE SYSTEM. AS FOR QPF AMOUNTS...THE GFS AND GEM
SOLUTIONS WERE GOOD COMPROMISES BETWEEN THE ECMWF AND GEM
OUTLIERS...SO I USED THOSE. THIS RESULTS IN AROUND 4 INCHES OF SNOW
STORM TOTAL.
ADDITIONAL SNOW WILL BE LIKELY BEHIND THE SYSTEM AS LES KICKS IN DUE
TO FALLING 850MB TEMPS IN GENERALLY NW WINDS BEHIND THE SYSTEM.
MODEL SOLUTIONS DIVERGE ON THIS POINT STARTING MONDAY EVENING. THE
GFS IS MUCH FASTER TO BRING A SFC RIDGE IN FROM THE W THAN THE ECMWF
AND GEM...THUS KILLING THE LES FASTER AS WINDS BECOME COMPLETELY
OFFSHORE BY 12Z TUE.
MODELS THEN BRING A STRONG LOW PRESSURE SYSTEM FROM THE CENTRAL
PLAINS TUESDAY TO SOMEWHERE S OF THE AREA WED. THERE HAS BEEN
CONSIDERABLE MODEL VARIABILITY WITH THE TRACK OF THIS SYSTEM. THIS
COMBINED WITH INCREASED ATTENTION TO THE SUN/MON STORM LEAD ME TO
USE A CONSENSUS OF MODEL GUIDANCE FOR THE TUE THROUGH THU PERIOD.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 118 PM EST FRI FEB 24 2012
CONTINUED NRLY FLOW/COOLER AIR WILL KEEP LES AT ALL TAF SITES DURING
FORECAST PERIOD. MAIN AREAS OF CONCERN ARE IWD AND SAW. PRECIP
MOVING IN FROM THE W IS CAUSING ALTERNATE LANDING MINIMUMS AT
IWD...AND CONDITIONS SHOULD PERSIST THROUGHOUT MUCH OF THE TAF
PERIOD AS WINDS TURN MORE NW AND LAKE EFFECT PROCESSES TAKE OVER.
SOME UPDATES MAY NEED TO BE MADE BASED ON WHERE LES DOES ACTUALLY
SET UP AS MODELS ARE HAVING A TOUGH TIME DISCERNING THE LOCATION AND
TIMING OF THE STRONGEST CONVERGENCE AREAS. REGARDLESS...EXPECT
CONDITIONS TO IMPROVE BY LATE SATURDAY MORNING AS DRIER AIR BEGINS
TO MOVE IN. SIMILAR STORY AT SAW...WITH FAVORABLE N WINDS AND
CURRENT IFR CONDITIONS. AS WINDS CONTINUE TO SHIFT TO A LESS FAVORED
NW DIRECTION THIS AFTERNOON...EXPECT CONDITIONS TO BE ON THE
IMPROVING TREND THROUGH THE NIGHT. KCMX WILL SEE THE POTENTIAL FOR
CONTINUED LES AS WELL...HOWEVER N/NNW WIND DIRECTION SHOULD BE LESS
FAVORABLE FOR ANY MAIN CONCERNS BELOW MVFR.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 521 AM EST FRI FEB 24 2012
ACTIVE WEATHER EXPECTED THRU THE MIDDLE OF NEXT WEEK WITH A
PROGRESSIVE REGIME BRINGING A SERIES OF LOW PRES AND HIGH PRES
SYSTEMS ACROSS THE GREAT LAKES REGION. DEEPENING LOW PRES HEADING
FROM THE OHIO VALLEY TO NEW ENGLAND WILL RESULT IN INCREASING
NORTHERLY WINDS TO 15-25KT TODAY AND TONIGHT. WINDS WILL DIMINISH
FROM W TO E SAT/SAT NIGHT AS HIGH PRES RIDGE ARRIVES. ALREADY BY
LATE SAT NIGHT WINDS WILL BE ON THE INCREASE AGAIN OVER WRN LAKE
SUPERIOR IN RESPONSE TO THE NEXT LOW PRES SYSTEM MOVING OUT OVER THE
NRN PLAINS. WINDS SHOULD INCREASE UP TO 30KT SUN AS THE LOW
APPROACHES. WITH THE LOW WEAKENING AS IT PASSES...WINDS ON THE
BACKSIDE OF THE SYSTEM MON WON`T BE AS STRONG...15-25KT SUN NIGHT
INTO EARLY MON. WINDS WILL CONTINUE TO DIMINISH INTO TUE AS HIGH
PRES ARRIVES. WINDS WILL BE ON THE INCREASE AGAIN WED AS THE NEXT
LOW PRES SYSTEM APPROACHES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL 11 AM EST /10 AM CST/ SATURDAY FOR
MIZ002-009.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...JLA
SHORT TERM...ROLFSON
LONG TERM...TITUS
AVIATION...JMW
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1230 PM EST FRI FEB 24 2012
.UPDATE...
ISSUED AT 1045 AM EST FRI FEB 24 2012
I HAVE UPDATED THE FORECAST PRODUCTS TO EXPAND THE WARNING
NORTHEAST TO INCLUDE OSCEOLA AND CLARE COUNTIES. WE HAVE RECEIVED
RELIABLE (THEY SENT PICTURES) REPORTS OF 10 TO 12 INCHES IN A
BAND FROM EVART TO HARRISON BY 8 AM. THE SNOW CONTINUES TO FALL
ACROSS THAT AREA AND SHOULD INTO EARLY THIS AFTERNOON SO IT MAKES
SENSE TO INCLUDE THEM IN A WARNING.
ELSEWHERE AND OTHERWISE THE FORECAST LOOKS TO BE ON TRACK. THE
DEFORMATION SNOW BANDS HAVE ROTATE SE INTO WESTERN AND CENTRAL
COUNTIES OF SOUTHWEST LOWER MICHIGAN. THE HRRR SUGGEST BY NOON
MOST OF THE MORE SIGNIFICANT SNOW WILL HAVE ENDED AND ONLY AND
INCH OR TWO SHOULD FALL THIS AFTERNOON.
LAKE EFFECT WILL DEVELOP THIS EVENING AND I COULD SEE 2 TO 4
INCHES FROM THAT TONIGHT INTO SATURDAY MORNING. WE MAY HAVE TO
EXPAND HEADLINES IN OUR SW MOST COUNTIES FOR THAT.
&&
.SHORT TERM...(TODAY THROUGH SATURDAY)
ISSUED AT 441 AM EST FRI FEB 24 2012
FORECAST CONCERNS DEAL WITH THE LOW MOVING ACROSS THE NORTHERN
OHIO VALLEY. CHANGES TO THE FORECAST MAINLY INCLUDE DELAYING THE
STEADIER SNOWFALL UNTIL THIS MORNING AND TRIMMING ACCUMS A BIT.
THIS HAS RESULTED IN THE DOWNGRADE OF THE WARNING TO AN ADVISORY
FOR THE SRN TIER OF COUNTIES.
LATEST RADAR TRENDS SHOW AN INCREASE IN COVERAGE AND INTENSITY
OVER THE CWA. WE/VE ALREADY HAD A REPORT OF 2 INCHES IN AN HOUR
OVER THE NRN CWA. THIS IS A TYPICAL FGEN EVENT THAT IS SLOW TO
DEVELOP AND FEATURES MANY HOLES IN THE RADAR COVERAGE. HOWEVER THE
SHORT WAVE DRIVING THIS IS STRENGTHEN AND WE SHOULD SEE HEAVIER
SNOW BETWEEN NOW AND LATE MORNING. MODELS SHOW STRONG UVV/S IN
THE DGZ EARLY THIS MORNING. THUS...THE MORNING COMMUTE SHOULD BE
HEAVILY IMPACTED. THE EXCEPTION WILL BE THE FAR SE CWA WHERE
SNOWFALL MAY NOT BE AS MUCH AS EARLIER EXPECTED.
THE TROWAL IS SETTING UP FROM OTTAWA COUNTY NORTHEASTWARD TOWARD
SAGINAW BAY AND THIS SHOULD BE WHERE THE AXIS OF HEAVY SNOW
DEVELOPS. I WOULD NOT BE SURPRISED TO SEE AREAS THAT SEE TOTAL
ACCUMS AROUND 3 INCHES AND AREAS THAT SEE 8 INCHES ACROSS THE
CENTRAL CWA.
REGIONAL RADAR SHOWS MODERATE TO HEAVY SNOW EXTENDING SWWD TO NW
ILLINOIS. GIVEN THE SLOWER DEVELOPMENT OF THE EVENT...WE EXTENDED
THE HEADLINES THROUGH THE AFTERNOON. THE NRN ROW OF COUNTIES WILL
SEE TOTAL ACCUMS IN THE 3-6 INCH RANGE.
AS THE LOW MOVES EAST THIS AFTERNOON/EVENING...THE FGEN SNOW WILL
DIMINISH AND LAKE EFFECT SNOWS WILL DEVELOP. H8 TEMPS APPEAR
MARGINAL FOR LAKE EFFECT BUT MOISTURE IS FAIRLY DEEP AND SO THE
TRADITIONAL NW FLOW AREAS COULD SEE 2 OR 3 INCHES OF ADDITIONAL
SNOWFALL TONIGHT/SATURDAY.
.LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY)
ISSUED AT 441 AM EST FRI FEB 24 2012
THE NEXT SYSTEM WILL BE A SFC LOW TRACKING FROM THE NRN PLAINS
ACROSS THE NRN GREAT LAKES REGION SUNDAY AND SUNDAY NIGHT. MOST OF
THE PCPN WITH THIS SYSTEM FALLS NEAR AND NORTH OF THE LOW TRACK SO
WILL CARRY ONLY LOW CHANCE POPS FOR A FEW LIGHT RAIN OR SNOW SHOWERS
IN NRN SECTIONS OF THE CWFA.
A VARIETY OF WEATHER CAN BE EXPECTED FROM A SLOW MOVING SYSTEM THAT
IS PROGGED TO TRACK FROM NEBRASKA TO MICHIGAN FOR TUESDAY AND
WEDNESDAY... THEN INTO NEW ENGLAND ON THURSDAY.
STRONG WARM ADVECTION AND GULF MOISTURE IN ADVANCE OF THE SFC LOW
SHOULD RESULT IN A MIXTURE OF WINTRY PCPN DEVELOPING TUESDAY OR
TUESDAY EVENING... FOLLOWED BY A QUICK CHANGEOVER TO PRIMARILY RAIN
LATE TUESDAY NIGHT AND WEDNESDAY MORNING.
STRONG COLD ADVECTION COMING AROUND THE SOUTH SIDE OF THE LOW AS IT
TRACKS INTO NRN LWR MI WILL BRING A CHANGEOVER BACK TO SNOW SHOWERS
WEDNESDAY AFTERNOON AND NIGHT. A FEW SNOW SHOWERS SHOULD CONTINUE
THURSDAY IN THE PERSISTENT CYCLONIC COLD ADVECTION PATTERN ON THE
BACK SIDE AS THE SFC LOW HEADS INTO NEW ENGLAND.
NO SIGNIFICANT SNOW IS EXPECTED BUT THERE COULD BE OVER A HALF INCH
OF RAIN IN SRN SECTIONS OF THE CWFA TUESDAY NIGHT AS STRONG LOW
LEVEL JET AND PWAT VALUES OVER ONE INCH IMPACT THE REGION.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1230 PM EST FRI FEB 24 2012
WIDESPREAD IFR/LIFR CONDITIONS AT 17Z WILL IMPROVE TO MVFR THIS
AFTERNOON AS SNOW DIMINISHES TO FLURRIES. NW WINDS WILL GUST TO NEAR
25 KTS AT TIMES THIS AFTN/EARLY EVE. CONDITIONS WILL STAY MVFR
TONIGHT DUE TO EXTENSIVE LOW CLOUDS AND LIGHT FOG. IN ADDITION WNW
FLOW LAKE EFFECT SNOW SHOWERS WILL CAUSE IFR CONDITIONS AT TIMES
OVERNIGHT THROUGH MIDDAY SATURDAY AT KMKG... KAZO AND POSSIBLE KGRR
AND KBTL DUE TO WEST TO WNW WINDS STAYING UP AROUND 10-15 KTS
OVERNIGHT.
&&
.MARINE...
ISSUED AT 441 AM EST FRI FEB 24 2012
KEPT THE SCA GOING MAINLY FOR WINDS TODAY. AFTER THE LOW MOVES
PAST THIS AFTERNOON AND WINDS BACK TO THE NORTHWEST...WAVES WILL
INCREASE.
&&
.HYDROLOGY...
ISSUED AT 441 PM EST THU FEB 23 2012
TEMPS IN THE 30S DURING THE NEXT FEW DAYS WILL LIMIT THE MELTING
OF THE SNOW THAT FALLS TODAY. AS SUCH...RIVERS WILL BE SLOWER TO
RESPOND AND SHOULD REMAIN BELOW ACTION STAGE.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER STORM WARNING UNTIL 5 PM EST THIS AFTERNOON FOR MIZ039-
040-043>046-050>052-056>059-064>067.
WINTER WEATHER ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
MIZ037-038-071>074.
LM...SMALL CRAFT ADVISORY UNTIL 7 PM EST SATURDAY FOR LMZ844>849.
&&
$$
UPDATE...WDM
SHORT TERM...93
LONG TERM....MEADE
AVIATION...LAURENS
MARINE...93
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1127 AM EST FRI FEB 24 2012
.UPDATE...
ISSUED AT 1126 AM EST FRI FEB 24 2012
SNOW OVER NORTH CENTRAL HAS INCREASED WITHIN LAST HOUR WITH
NORTHERLY WINDS OFF LK SUPERIOR AND SOME HELP FROM FRINGE OF SYSTEM
MOVING BY TO THE SOUTHEAST. VIS SATELLITE INDICATES MID CLOUDS
STREAMING NORTH WHILE OVR FLOW OVR LK SUPERIOR IS MORE NORTHERLY.
INVERSION TOP IS AROUND 5-7KFT PER VWP AND TEMPS AT TOP OF INVERSION
ARE AROUND -12C. GIVEN THE ADDED SYNOPTIC SUPPORT THIS IS SEEMING
GOOD ENOUGH FOR LAKE ENHANCEMENT. SNOW AMOUNTS SO FAR ARE AROUND A
HALF INCH...BUT IT REALLY HAS BEEN ONLY SNOWING FOR HALF HOUR. 1.5
DEGREE REFLECTIVITY OF KMQT RADAR INDICATES HIGHER REFLECTIVITIES
NORTH OF BIG BAY ARE SHRINKING TOWARD MARQUETTE COUNTY SHORE...SO
UPTICK IN SNOW MAY SETTLE BACK DOWN IN NEXT HOUR OR TWO. NORTH WINDS
SHOULD CONTINUE REST OF THE AFTN SO HAVE INCREASED POPS FOR
MARQUETTE/ALGER. BUMPED UP SNOW AMOUNTS TO 2-4 INCHES FOR REST OF
DAY. OUT WEST...KDLH RADAR INDICATES THAT HEAVIER BANDS OF LK EFFECT
ARE ABOUT TO BEGIN TO MOVE INTO WESTERN CWA. ADVY APPEARS GOOD THERE
ATTM. A BIT CONCERNED THAT BASED ON FCST CONVERGENCE FM HIGHER
RESOLUTION 12Z MODELS...THAT EVENTUALLY FAR NORTHERN GOGEBIC AND MUCH
OF NORTHERN ONTONAGON COULD GET INTO PERIOD OF HEAVIER SNOW LATE AFTN
THROUGH TONIGHT AND MAY NEED AN EVENTUAL WARNING. WILL CONTINUE TO
EVALUATE THIS DURING AFTN ONCE THE SNOW SETS UP OVR THE FAR WEST. &&
.SHORT TERM...(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 521 AM EST FRI FEB 24 2012
WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A TROF OVER THE CNTRL
CONUS. A VIGOROUS LOOKING SHORTWAVE TRACKING E INTO IL WAS
SUPPORTING A BAND OF SNOW FROM ERN IA ACROSS SRN WI/NRN IL INTO LWR
MI. UPSTREAM....A SHORTWAVE TROF EXTENDS FROM SRN MANITOBA THRU THE
ERN DAKOTAS/WRN MN WITH VORT MAX APPARENT OVER SE MANITOBA. AT THE
SFC...OBS INDICATE ASSOCIATED WEAK SFC LOW N OF KINL WITH TROF
EXTENDING SE TOWARD WRN LAKE SUPERIOR...AND KDLH RADAR SHOWS A BAND
OF -SN ALONG THE TROF. CLOSER TO HOME...MOISTURE EXTENDING TO AROUND
6KFT PER FCST SOUNDINGS AND IMPLIED BY KMQT VAD WIND PROFILE ALONG
WITH 850MB TEMPS OF -9/-10C IS SUPPORTING FLURRIES/-SHSN OFF LAKE
SUPERIOR INTO NCNTRL UPPER MI. -SHSN TRENDS OVERNIGHT HAVE BEEN ODD
WITH UNORGANIZED SNOW AREAS DEVELOPING AND INTENSIFYING OVER THE
WATER ONLY TO PERSIST FOR A WHILE AND THEN RAPIDLY WEAKEN. SHORT
TERM FCST CONCERNS WILL REVOLVE AROUND SHORTWAVE TO THE NW...AND THE
AFFECTS IT WILL HAVE ON LAKE EFFECT LATER TODAY THRU TONIGHT.
00Z CWPL SOUNDING PROBABLY GIVES A DECENT REPRESENTATION OF AIR MASS
THAT WILL BE OVER THE WRN FCST AREA LATER TODAY/TONIGHT. IF SO...
850MB TEMPS WILL DROP A COUPLE OF DEGREES C AND COLUMN MOISTURE WILL
DEEPEN SIGNIFICANTLY. MODEL GUIDANCE IS IN GOOD AGREEMENT ON THIS
COOLING/MOISTENING. AT THE SAME...TIME WEAK DEEP LAYER FORCING WILL
OVERSPREAD WRN LAKE SUPERIOR/WRN UPPER MI IN ASSOCIATION WITH
AFOREMENTIONED SHORTWAVE TO THE NW. AT THE LOW LEVELS...THERE IS
GOOD AGREEMENT AMONG NUMEROUS MODELS THAT APPROACHING SFC TROF WILL
BASICALLY HANG UP OVER WRN LAKE SUPERIOR THIS AFTN (ESPECIALLY LATE)
AND TONIGHT FROM THE MN ARROWHEAD TO GOGEBIC/ONTONAGON COUNTIES. THE
RESULTING SHARP CONVERGENCE SHOULD REALLY AID LAKE ENHANCEMENT
POTENTIAL. WITH SNOW RATIOS OVERALL PROBABLY A LITTLE UNDER 20:1...
EVENT SHOULD EASILY EXCEED LOWER RATIO ADVY CRITERIA SNOWFALL (3
INCHES OR MORE IN 12HRS) WHERE LOW-LEVEL CONVERGENCE IS MAXIMIZED...
PROBABLY IN A FAIRLY SMALL AREA FROM KIWD TO WAKEFIELD...BERGLAND
AND WHITE PINE. PLAN TO RUN ADVY FOR ONTONAGON/GOGEBIC FROM 21Z
TODAY TO 15Z SAT FOR TOTAL SNOW ACCUMULATION OF 5-9 INCHES. EMPHASIS
WILL BE ON THE AREA MENTIONED. WITH SOME LES ALEADY NOTED OVER WRN
LAKE SUPERIOR ON KDLH RADAR AND A DECENT BAND OF SYNOPTIC SNOW
ASSOCIATED WITH APPROACHING SFC TROF...IT`S NOT OUT OF THE QUESTION
THAT SNOWFALL COULD BECOME QUITE A BIT HEAVIER THAN CURRENTLY
ANTICIPATED. WILL NEED TO WATCH MORNING/AFTN TRENDS FOR POTENTIAL
UPGRADE TO WARNING. ELSEWHERE ALONG LAKE SUPERIOR...SLIGHT COOLING
OF AIR MASS AND STRENGTHENING NORTHERLY WINDS WILL LEAD TO AN
INCREASE IN LES THIS AFTN INTO TONIGHT. ACCUMULATIONS WILL BE
LIGHTER THAN OVER THE FAR W DUE TO LESS INFLUENCE FROM SHORTWAVE...
SHALLOWER MOISTURE AND WEAKER LOW-LEVEL CONVERGENCE. WITH LONGER
FETCH AND MORE FAVORABLE WIND DIRECTION...SOME LOCATIONS FROM ERN
MARQUETTE COUNTY INTO ALGER COUNTY MAY SEE A FEW INCHES OF SNOW THRU
SAT MORNING.
DRIER AIR...LOWERING INVERSION AND INCREASINGLY ANTICYCLONIC FLOW AS
WINDS BACK WILL LEAD TO DIMINISHING LES SAT. WITH 850MB TEMPS AROUND
-14C...PROBABLY WON`T SEE LES COMPLETELY END SAT AFTN.
ANY LINGERING LES/FLURRIES WILL END SAT EVENING AS SFC HIGH PRES
RIDGE SHIFTS ACROSS THE AREA. MIGHT BE A WINDOW FOR TEMPS TO PLUMMET
BEFORE HIGH CLOUDS INCREASE/THICKEN FROM W TO E DURING THE NIGHT.
BEST OPPORTUNITY WOULD PROBABLY BE OVER THE CNTRL DUE TO LONGER
PERIOD BTWN DEPARTURE OF LAKE STRATOCU AND INCREASE OF HIGH CLOUDS.
.LONG TERM...(SUNDAY THROUGH THURSDAY)
ISSUED AT 521 AM EST FRI FEB 24 2012
A 500MB SHORTWAVE TROUGH CURRENTLY OVER THE PACIFIC NW CONUS WILL
HAVE MOVED INTO THE NRN PLAINS BY THE START OF THE PERIOD 12Z
SUN...SPINNING UP A SFC LOW AS IT MOVED LEEWARD OF THE ROCKIES. THE
SFC LOW IS DEPICTED BY MODELS TO BE OVER ERN SD AT 12Z SUN. MODELS
STILL VARY IN THE INTENSITY OF THE SYSTEM AT THIS POINT...AND
THROUGH THE TIME THE SYSTEM PASSES OVER THE CWA. THE 12Z/23 ECMWF
AND 00Z/24 GEM ARE ON THE STRONGER SIDE OF GUIDANCE WITH THE SFC LOW
AROUND 996MB AT 12Z SUN...WHILE THE 00Z/24 GFS AND 00Z/24 NAM SHOW THE
SFC LOW AT 1002MB. ASSIDE FROM SYSTEM STRENGTH...MODELS ARE IN GOOD
AGREEMENT ON THE TRACK AND FAIR AGREEMENT ON THE SPEED OF THE
SYSTEM...WITH THE DEEPER ECMWF AND GEM BEING ON THE SLOW SIDE OF
GUIDANCE. USED A CONSENSUS OF THE MODELS FOR THE SPEED OF THE
SYSTEM...WHICH IS WEAKENING AS THE SHORTWAVE GETS SHEARED APART WITH
EASTWARD MOVEMENT.
WITH THAT IN MIND...THE SFC LOW /AND UPPER SHORTWAVE OVER OR JUST N
OF THE SFC LOW/ MOVES TO NEAR IRONWOOD BY 00Z MON. THE SFC LOW THEN
MOVES ACROSS UPPER MI...BEFORE MOVING TO THE FAR ERN CWA BY 12Z MON.
THIS TRACK CONFINES THE HEAVIEST SNOW /AND IT IS EXPECTED TO BE ALL
SNOW/ TO FAR NRN UPPER MI AND LAKE SUPERIOR. SYNOPTIC SNOW LOOKS TO
BE JUST MOVING INTO THE WRN CWA AROUND 12Z SUN...COVERING ROUGHLY
THE WRN HALF OF UPPER MI BY 18Z. THERE IS THE POSSIBILITY FOR SOME
LES OVER ERN UPPER MI IN THE ANTICYCLONIC FLOW AND 850MB TEMPS
AROUND -12C AHEAD OF THE SYSTEM...BUT WILL KEEP THAT AT CHANCE POPS
FOR NOW. IT THEN LOOKS LIKE A DRY SLOT WILL ROTATE IN...ESPECIALLY
OVER THE SRN CWA. THE GFS CRANKS OUT AROUND 0.4 INCHES OF QPF OVER
MUCH OF UPPER MI THROUGH 12Z MON...BEFORE THE SYSTEM MOVES OUT AND
LES STARTS. THE NAM SHOWS CLOSER TO 0.5 INCHES OVER MUCH OF THE
AREA. THE ECMWF SHOWS AROUND 0.4 INCHES OF QPF OVER THE KEWEENAW
PENINSULA AND LAKE SUPERIOR...WITH AROUND 0.2 INCHES OVER ALL BUT
SRN MENOMINEE COUNTY WHERE IT SHOWS LESS THAN 0.1 INCHES. THE GEM IS
VERY CLOSE TO THE GFS SOLUTION FOR QPF. THERE ARE SIGNALS THAT
INDICATE WE MAY GET A HEAVIER BAND OF SNOW ALONG THE WARM FRONT THAT
SURGES NORTHWARD LATE SUNDAY...WHICH WOULD FAVOR AREAS OF S CENTRAL
AND ERN UPPER MI TO GET SOME HEAVIER SNOW. WILL NOT PUT THIS DETAIL
INTO THE GRIDS JUST YET SINCE THERE IS STILL SOME UNCERTAINTY IN THE
TRACK/TIMING OF THE SYSTEM. AS FOR QPF AMOUNTS...THE GFS AND GEM
SOLUTIONS WERE GOOD COMPROMISES BETWEEN THE ECMWF AND GEM
OUTLIERS...SO I USED THOSE. THIS RESULTS IN AROUND 4 INCHES OF SNOW
STORM TOTAL.
ADDITIONAL SNOW WILL BE LIKELY BEHIND THE SYSTEM AS LES KICKS IN DUE
TO FALLING 850MB TEMPS IN GENERALLY NW WINDS BEHIND THE SYSTEM.
MODEL SOLUTIONS DIVERGE ON THIS POINT STARTING MONDAY EVENING. THE
GFS IS MUCH FASTER TO BRING A SFC RIDGE IN FROM THE W THAN THE ECMWF
AND GEM...THUS KILLING THE LES FASTER AS WINDS BECOME COMPLETELY
OFFSHORE BY 12Z TUE.
MODELS THEN BRING A STRONG LOW PRESSURE SYSTEM FROM THE CENTRAL
PLAINS TUESDAY TO SOMEWHERE S OF THE AREA WED. THERE HAS BEEN
CONSIDERABLE MODEL VARIABILITY WITH THE TRACK OF THIS SYSTEM. THIS
COMBINED WITH INCREASED ATTENTION TO THE SUN/MON STORM LEAD ME TO
USE A CONSENSUS OF MODEL GUIDANCE FOR THE TUE THROUGH THU PERIOD.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 628 AM EST FRI FEB 24 2012
INCREASING NRLY FLOW/COOLER AIR WILL BRING LAKE EFFECT SNOW TO
KIWD/KCMX/KSAW DURING THIS FCST PERIOD. KIWD SHOULD BE MOST AFFECTED
AS APPROACHING MID LEVEL DISTURBANCE AND ASSOCIATED SFC TROF FOCUS
SNOW INTO FAR WRN UPPER MI. EXPECT VFR CONDITIONS TO START AT KIWD
TO DROP TO IFR AT TIMES IN THE NEXT FEW HRS AS WINDS SHIFT OFF THE
LAKE. CONDITIONS SHOULD THEN SETTLE TO MVFR BEFORE DROPPING TO
PREVAILING IFR LATER IN THE AFTN THRU TONIGHT AS TROF/CONVERGENT
FLOW SET UP ACROSS WRN LAKE SUPERIOR INTO FAR WRN UPPER MI. AT
KCMX...MVFR CONDITIONS SHOULD MOSTLY PREVAIL THOUGH SOME PERIODS OF
IFR ARE POSSIBLE. AT KSAW...INCREASINGLY NORTHERLY FLOW/UPSLOPE
WILL BRING LOWER MVFR CONDITIONS TODAY WITH -SHSN BECOMING MORE
FREQUENT. SOME PERIODS OF IFR ARE POSSIBLE. SLIGHT BACKING OF WINDS
TONIGHT SHOULD RESULT IN IMPROVING VIS AS MORE PERSISTENT/HEAVIER
SNOW SHOWERS SHIFT E.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 521 AM EST FRI FEB 24 2012
ACTIVE WEATHER EXPECTED THRU THE MIDDLE OF NEXT WEEK WITH A
PROGRESSIVE REGIME BRINGING A SERIES OF LOW PRES AND HIGH PRES
SYSTEMS ACROSS THE GREAT LAKES REGION. DEEPENING LOW PRES HEADING
FROM THE OHIO VALLEY TO NEW ENGLAND WILL RESULT IN INCREASING
NORTHERLY WINDS TO 15-25KT TODAY AND TONIGHT. WINDS WILL DIMINISH
FROM W TO E SAT/SAT NIGHT AS HIGH PRES RIDGE ARRIVES. ALREADY BY
LATE SAT NIGHT WINDS WILL BE ON THE INCREASE AGAIN OVER WRN LAKE
SUPERIOR IN RESPONSE TO THE NEXT LOW PRES SYSTEM MOVING OUT OVER THE
NRN PLAINS. WINDS SHOULD INCREASE UP TO 30KT SUN AS THE LOW
APPROACHES. WITH THE LOW WEAKENING AS IT PASSES...WINDS ON THE
BACKSIDE OF THE SYSTEM MON WON`T BE AS STRONG...15-25KT SUN NIGHT
INTO EARLY MON. WINDS WILL CONTINUE TO DIMINISH INTO TUE AS HIGH
PRES ARRIVES. WINDS WILL BE ON THE INCREASE AGAIN WED AS THE NEXT
LOW PRES SYSTEM APPROACHES.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY FROM 4 PM EST /3 PM CST/ THIS AFTERNOON
TO 11 AM EST /10 AM CST/ SATURDAY FOR MIZ002-009.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...JLA
SHORT TERM...ROLFSON
LONG TERM...TITUS
AVIATION...ROLFSON
MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
410 PM CST FRI FEB 24 2012
.DISCUSSION...
TONIGHT AND SATURDAY...COLD FRONT DROPPING THROUGH THE REGION THIS
AFTN HAS JUST ABOUT CLEARED MN AND IS ENTERING NRN IA AND SW WI.
BANDS OF -SHSN DRIFTING SE THROUGH CENTRAL-SOUTHERN MN...MOST OF
WHICH IS NOT REACHING THE GROUND BUT WHERE IT HAS BEEN REPORTED IT
HAS BEEN BRIEFLY MODERATE. THE OVERALL MASS OF PRECIP WILL SHIFT E
THROUGH THE EVENING AND EARLY MRNG HOURS BEFORE DISSIPATING BY
DAYBREAK SAT MRNG. ANY ACCUMULATIONS WILL BE LESS THAN AN INCH...
LIKELY HARDLY ANYTHING MORE THAN A DUSTING WITH SUCH DRY LOWER
LEVELS /DEWPOINT DEPRESSIONS ARE GENERALLY 10-15 DEGREES F/. THE
CDFNT IS BEING USHERED ALONG BY A CLOSED UPPER LOW NEAR KINL THAT
WILL SHIFT SE AND DEGENERATE INTO AN OPEN TROUGH. THIS WILL ALLOW
FOR CAA TO KICK IN ALONG WITH BRINGING IN ADDITIONAL DRIER AIR
WITH GRADUALLY CLEARING SKIES LATE TONIGHT THRU TMRW. TEMPS TNGT
WILL RANGE FROM THE UPPER SINGLE DIGITS TO LOWER TEENS. AS SHARP
UPPER RIDGING MOVES ACRS THE AREA TMRW...CAA WILL CONTINUE WHILE
THE FIRST HALF OF THE DAY WILL SEE AT LEAST PARTIALLY CLEARING
SKIES. SOME CONFLICTING MODEL INFORMATION AS TO HOW MUCH CLEARING
WILL TAKE PLACE THRU THE FIRST HALF OF THE DAY...BUT WILL PLAY A
MIDDLE-OF-THE-ROAD FCST AND GO WITH PTLY CLDY. HIGHS WILL REBOUND
TO THE MID TO UPR 20S.
SATURDAY NIGHT THROUGH MONDAY...AS UPPER RIDGING MOVES INTO THE
GREAT LAKES SAT EVENING...MOISTURE ASSOCIATED WITH A SYSTEM MOVING
IN OFF THE PACIFIC WILL INFILTRATE THE AREA SAT EVENING. THE
SYSTEM WILL THEN GET CAUGHT UP WITH A MODEST UPPER TROUGH OVER THE
NRN PLAINS AND THE COMBINATION WILL E THROUGH THE DAKOTAS AND NRN
MN SUNDAY AND INTO THE NRN GREAT LAKES SUN NIGHT. THE LACK OF A
GULF OF MEXICO MOISTURE SOURCE WILL KEEP THE SOURCE MOISTURE OF
THIS SYSTEM ON THE NRN SIDE...MEANING THAT NRN MN WILL BE THE
FOCUS FOR HEAVIER SNOWFALL. THAT SAID...THERE WILL STILL BE A
SWATH OF 1-3 INCH SNOWFALL FOR THE NRN 2/3 OF THE WFO MPX CWFA FOR
SUN INTO SUN NIGHT. IN ADDITION...WARMER AIR BEING BROUGHT UP ON
THE SRN SIDE OF THIS SYSTEM MAY CONVERT THE PRECIP TO A RAIN/SNOW
MIX...OR EVEN ALL RAIN...FOR A PERIOD OF TIME SUN AFTN WHICH WOULD
SQUELCH HIGHER SNOWFALL ACCUMULATIONS. THIS SYSTEM WILL THEN EJECT
INTO THE GREAT LAKES SUN NIGHT INTO MONDAY...ALLOWING HIGH
PRESSURE TO DROP IN FROM SRN CANADA IN CONJUNCTION WITH UPPER
RIDGING AND ANOTHER BOUT OF COLD AIR ADVECTION. HIGHS IN THE MID
30S TO AROUND 40 ON SUNDAY WILL DROP TO THE 20-30 RANGE ON MONDAY.
MONDAY NIGHT THROUGH THURSDAY...THIS PORTION OF THE FORECAST STILL
BEARS THE MOST WATCHING AS IT HAS THE POTENTIAL TO BE QUITE
ACTIVE. A DEEP TROUGH OVER THE SOUTHWESTERN CONUS WILL EXPAND AND
PIVOT OVER THE ROCKIES...CONTRIBUTING TO STRONG CYCLOGENESIS OVER
THE CENTRAL PLAINS. AS THE TROUGH BECOMES NEGATIVELY TILTED...IT
WILL SHOVE A DEEPENING SFC LOW PRES CENTER FROM CO/NE INTO SD/SRN
MN. FOR THIS SYSTEM...THE GULF OF MEXICO IS OPEN FOR BUSINESS...
SO TO SPEAK...BRINGING A DEEP TAP OF MOISTURE UP TO THE NRN PLAINS
AND UPPER MISSISSIPPI RIVER VALLEY IN ADVANCE OF THIS SYSTEM. WHAT
IS VERY TRICKY IS THE TRACK OF THIS SYSTEM. THE GFS/GEM CAMP HAS
SHIFTED THE TRACK FURTHER N...WHICH WOULD SUPPRESS SNOWFALL
AMOUNTS AND EVEN BRING A RAIN-SNOW-DRY SLOT-SNOW PATTERN TO THE
AREA FOR THIS SYSTEM. THE MORE SRN TRACK OF THE ECMWF WOULD BRING
HIGHER SNOW AMOUNTS TO SRN MN INTO WRN WI. ALL MODELS OUTPUT OVER
1 INCH QPF ALONG WITH A MSLP NEAR 980MB...SO THE POTENTIAL IS
THERE FOR HIGH SNOWFALL AMOUNTS AND POSSIBLE CONVECTIVE BANDS.
HAVE NUDGED POPS INTO THE 60-70 PERCENT RANGE BECAUSE THERE IS
HIGH CONFIDENCE OF PRECIP OCCURRENCE...BUT THERE IS LOW CONFIDENCE
AT THIS POINT OF P-TYPE AND PRECIP AMOUNT WITH THIS SYSTEM. THE
SYSTEM WILL LIFT NE INTO THE GREAT LAKES WED...ALLOWING A BRIEF
RESPITE FOR WED NIGHT AHEAD OF A WEAK WAVE PUSHING THROUGH THE
REGION THU THAT COULD PRODUCE ADDITIONAL MINOR SNOW ACCUMULATION.
&&
.AVIATION.../18Z TAF ISSUANCE/
COMBINATION OF CYCLONIC FLOW AND COLD AIR ALOFT HAS RESULTED IN
PLENTY OF CLOUD COVER ACROSS THE AREA TODAY. IN ADDITION...
STEEPENING LOW LEVEL LAPSE RATES HELPING TO GENERATE SOME
FLURRIES/SNOW SHOWS...WHICH THE HRRR HAS CONTINUING ALL THE WAY
OUT TO 03Z...THOUGH THROUGH 00Z IS WHEN -SN WILL BE MOST LIKELY.
CIGS ARE STRADDLING THE MVFR CATEGORY THIS AFTERNOON...AND SHOULD
STAY HIGH MVFR/LOW VFR. MVFR CIGS MAINLY ASSOCIATED WITH CLOUDS
COMING DOWN FROM ERN NODAK/NW MN...AND EXPECT CONDITIONS TO REMAIN
MAINLY VFR UNTIL THESE CLOUDS SWEEP ACROSS THE AREA. AFTER
THAT...WILL BE A SLOW GO TO KICK CLOUDS OUT TONIGHT. NAM/GFS
SIMILAR WITH BRINGING LOW LEVEL RIDGE IN TO FAR WRN MN AROUND
12Z...WITH CLEARING SLOWLY WORKING ACROSS THE AREA THROUGH THE
MORNING/AFTERNOON ON SATURDAY. DELAYED IMPROVEMENTS TO VFR BY A
FEW HOURS AT MN TERMINALS...WITH MVFR CIGS LIKELY HANGING ON AT WI
TERMINALS UNTIL AFTER 18Z SATURDAY. FOR WINDS...EXPECT GUSTS TO
CONTINUE UNTIL 00Z...BEFORE FALLING OFF. WINDS WILL REMAIN AOA 10
KTS HOWEVER THROUGH MOST OF THE NIGHT UNTIL SFC RIDGE SLACKENS
THEM OFF AND STARTS TO TURN THEM MORE WRLY ACROSS MN SAT MORNING.
KMSP...WATCHING -SHSN DROPPING SE FROM CENTRAL MN THIS AFTERNOON
AND SHOULD GIVE US BOUTS OF MVFR CIGS A POSSIBLY IFR VSBYS AS THE
SHOWERS PASS. EXISTING TEMPO GROUP COVERED THE THREAT WELL. DO NOT
EXPECT LOWER CLOUDS TO IMPROVE UNTIL BETWEEN 15Z AND 18Z SATURDAY.
30 KT GUST APPEARS TO HAVE BEEN A ONE HIT WONDER AND EXPECT NW
WINDS TO GUST TO BETWEEN 22 AND 26 KTS THROUGH THE REST OF THE
AFTERNOON. WILL HAVE TO DEAL WITH A WIND SHIFT LATE IN THE PERIOD
AS SFC RIDGE WORKS THROUGH.
//OUTLOOK...SATURDAY NIGHT THROUGH WEDNESDAY...
.SATURDAY NIGHT...MVFR POSSIBLE LAT WITH CHANCE OF SN.
.SUNDAY...MVFR POSSIBLE WITH CHANCE OF RA/SN.
.MONDAY...VFR
.TUESDAY AND WEDNESDAY...MVFR TO IFR POSSIBLE IN RA/SN AS
SIGNIFICANT WINTER STORM POTENTIALLY IMPACTS THE REGION.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
JPC/MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1157 AM CST FRI FEB 24 2012
.UPDATE...
18Z AVIATION DISCUSSION ADDED BELOW.
&&
.DISCUSSION...
NEXT SEVERAL DAYS CONTINUES TO LOOK LIKE THEY WILL REMAIN ACTIVE AS
TWO STRONG SYSTEMS BY THIS WINTER`S STANDARDS AFFECT THE AREA. THE
FIRST WILL ARRIVE SUNDAY WITH THE NEXT STRONGER SYSTEM ON TUESDAY
INTO WEDNESDAY.
IN THE SHORT TERM PRESSURE GRADIENT HAS BEEN TIGHTENING OVERNIGHT AS
LOW PRESSURE IN OHIO VALLEY LIFTS NORTHEAST ALLOWING NORTHERLY WINDS
TO INCREASE ACROSS THE AREA. COLD ADVECTION AND MAINLY CLOUDY SKIES
WILL LIMIT TEMPERATURE RISES TODAY WITH MOST AREAS NOT SEEING
AFTERNOON TEMPS MUCH DIFFERENT THAN CURRENT READINGS. N-S BAND OF
-SN CURRENTLY PUSHING ACROSS E MN AHEAD OF UPPER TROF WILL PUSH
ACROSS WC WI NEXT FEW HOURS PRODUCING PERHAPS A HALF INCH OF SNOW.
WEAK WAVES COMING DOWN IN NW FLOW WILL MAINTAIN CHANCE OF PERIODS OF
-SN THRU THE DAY WITH LITTLE IF ANY ACCUM.
FOR TONIGHT NARROW RIDGE OF HIGH PRESSURE ADVANCES ACROSS THE DKTS
INTO W MN BRINGING SOME CHILLY TEMPS WITH SOME SINGLE DIGITS
POSSIBLE. CONTINUED GRADIENT AND SOME CLOUDS SHOULD KEEP TEMPS IN
THE TEENS ELSEWHERE.
SOUTHERLY FLOWS DEVELOPS DURING THE DAY SATURDAY AS UPSTREAM SYSTEM
NOW OFF THE B.C.COAST MOVES ACROSS THE N ROCKIES INTO NORTHERN
PLAINS. MODELS PRETTY MUCH IN AGREEMENT IN BRINGING THIS PACIFIC
SURFACE LOW PRESSURE ACROSS CENTRAL MN DURING THE DAY ON SUNDAY
KEEPING MAIN SNOW TOTALS TO OUR NORTH. SYSTEM STARTS OUT FAIRLY DRY
WITH PWATS LESS THAN .20 AND DOESN`T DEVELOP A GOOD GULF TAP...WITH
VALUES RISING TO .30 TO .40 ON SUNDAY. ENUF WARM AIR PULLED NORTH
THAT A -RA/-SN MIX LOOKS FAIRLY LIKELY IN LOW QPF AREA SOUTH OF
SURFACE LOW IN S AREAS. AROUND 8C 200 MB WAA CROSS N MN WOULD IMPLY
4-6 INCHES OF SNOW. WILL TREND SNOW AMOUNTS FROM THE 4 INCH RANGE
ACROSS N CWA TO NEAR ZERO ALONG IA BORDER. MAY END UP WITH WINTER
WX ADVYS...ESPECIALLY ACROSS PORTIONS WC AND CENTRAL MN FOR COMBO OF
SNOW AND WIND WITH MODELS ALL DEVELOPING TIGHT PRESSURE GRADIENT
BEHIND SURFACE LOW.
A BREAK IN ACTION FOR MONDAY BEFORE DEEPENING S PLAINS LOW LIFTS
NORTHEAST TOWARD AREA AS ASSOCIATED UPPER TROF BECOMES NEGATIVE IN
ITS APPROACH TOWARD OUR AREA ON TUESDAY INTO WEDNESDAY. ATTM GFS
AND ECMWF OPERATIONAL RUNS TRACK SURFACE LOW OUT OF NW IA THEN
ACROSS EXTREME SE MN. THIS WOULD FAVOR HEAVY SNOWS ACROSS CENTRAL
MN INTO NW WI AND NE MN. GEM CURRENTLY AN OUTLIER TRACKING SURFACE
LOW MUCH FARTHER WEST. THIS SYSTEM HAS THE POTENTIAL OF BEING A
HEAVY SNOW PRODUCER WITH MUCH BETTER GULF FETCH. ANOTHER POTENTIAL
FLY IN OINTMENT IS POSSIBILITY OF RAIN DEVELOPING IN S AREAS ON
TUESDAY WITH WEDGE OF WARM AIR ADVANCING NORTH AHEAD OF SURFACE LOW.
&&
.AVIATION.../18Z TAF ISSUANCE/
COMBINATION OF CYCLONIC FLOW AND COLD AIR ALOFT HAS RESULTED IN
PLENTY OF CLOUD COVER ACROSS THE AREA TODAY. IN ADDITION...
STEEPENING LOW LEVEL LAPSE RATES HELPING TO GENERATE SOME
FLURRIES/SNOW SHOWS...WHICH THE HRRR HAS CONTINUING ALL THE WAY
OUT TO 03Z...THOUGH THROUGH 00Z IS WHEN -SN WILL BE MOST LIKELY.
CIGS ARE STRADDLING THE MVFR CATEGORY THIS AFTERNOON...AND SHOULD
STAY HIGH MVFR/LOW VFR. MVFR CIGS MAINLY ASSOCIATED WITH CLOUDS
COMING DOWN FROM ERN NODAK/NW MN...AND EXPECT CONDITIONS TO REMAIN
MAINLY VFR UNTIL THESE CLOUDS SWEEP ACROSS THE AREA. AFTER
THAT...WILL BE A SLOW GO TO KICK CLOUDS OUT TONIGHT. NAM/GFS
SIMILAR WITH BRINGING LOW LEVEL RIDGE IN TO FAR WRN MN AROUND
12Z...WITH CLEARING SLOWLY WORKING ACROSS THE AREA THROUGH THE
MORNING/AFTERNOON ON SATURDAY. DELAYED IMPROVEMENTS TO VFR BY A
FEW HOURS AT MN TERMINALS...WITH MVFR CIGS LIKELY HANGING ON AT WI
TERMINALS UNTIL AFTER 18Z SATURDAY. FOR WINDS...EXPECT GUSTS TO
CONTINUE UNTIL 00Z...BEFORE FALLING OFF. WINDS WILL REMAIN AOA 10
KTS HOWEVER THROUGH MOST OF THE NIGHT UNTIL SFC RIDGE SLACKENS
THEM OFF AND STARTS TO TURN THEM MORE WRLY ACROSS MN SAT MORNING.
KMSP...WATCHING -SHSN DROPPING SE FROM CENTRAL MN THIS AFTERNOON
AND SHOULD GIVE US BOUTS OF MVFR CIGS A POSSIBLY IFR VSBYS AS THE
SHOWERS PASS. EXISTING TEMPO GROUP COVERED THE THREAT WELL. DO NOT
EXPECT LOWER CLOUDS TO IMPROVE UNTIL BETWEEN 15Z AND 18Z SATURDAY.
30 KT GUST APPEARS TO HAVE BEEN A ONE HIT WONDER AND EXPECT NW
WINDS TO GUST TO BETWEEN 22 AND 26 KTS THROUGH THE REST OF THE
AFTERNOON. WILL HAVE TO DEAL WITH A WIND SHIFT LATE IN THE PERIOD
AS SFC RIDGE WORKS THROUGH.
//OUTLOOK...SATURDAY NIGHT THROUGH WEDNESDAY...
.SATURDAY NIGHT...MVFR POSSIBLE LAT WITH CHANCE OF SN.
.SUNDAY...MVFR POSSIBLE WITH CHANCE OF RA/SN.
.MONDAY...VFR
.TUESDAY AND WEDNESDAY...MVFR TO IFR POSSIBLE IN RA/SN AS
SIGNIFICANT WINTER STORM POTENTIALLY IMPACTS THE REGION.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
BAP/MPG
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1200 PM CST FRI FEB 24 2012
.AVIATION...SCATTERED SNOW SHOWERS ARE EXPECTED THIS
AFTERNOON...ESPECIALLY ALONG AND NORTHEAST OF A LINE FROM KAIA TO
KLBF. OUTSIDE OF ANY SNOW SHOWER ACTIVITY...VFR CONDITIONS SHOULD
BE THE RULE...BUT MVFR EXPECTED IN SNOW SHOWERS. SFC WINDS WILL BE
W TO NW AT 15 TO 25 KTS.
&&
PREV DISCUSSION... /ISSUED 352 AM CST FRI FEB 24 2012/
SHORT TERM...TODAY THROUGH SUNDAY NIGHT
FAIRLY ACTIVE PATTERN THROUGH THE NEXT WEEK WITH THE SHORT TERM
FOCUS ON FRIDAY WITH A WEAK SHORTWAVE TROUGH MOVING ACROSS THE
AREA WITH CHANCES FOR SNOW SHOWERS AND WINDY CONDITIONS AGAIN. A
BRIEF WARM UP IS EXPECTED FOR SATURDAY...ALONG WITH WINDY
SOUTHERLY WINDS...THEN FOCUS TURNS TO PRECIPITATION CHANCES AND
WINDS AGAIN ON SUNDAY AND SUNDAY NIGHT AS THE NEXT SYSTEM MOVES
ACROSS THE AREA.
AT 08Z WATER VAPOR SHOWED THE TROUGH THAT BROUGHT THE STRONG WINDS
TO THE AREA YESTERDAY HAD PUSHED INTO MISSOURI AND ILLINOIS WITH
RIDGING CONTINUING OVER THE WESTERN CONUS...KEEPING THE LOCAL AREA
UNDER NORTHWEST FLOW. LOOKING UPSTREAM...IS SOME DARKENING IN THE
WATER VAPOR OVER ALBERTA WHICH IS CONFIRMED BY LOWERED PRESSURE ON
THE 1.5PV SURFACE BY THE RUC ANALYSIS. FURTHER UPSTREAM...A ROBUST
SHORTWAVE TROUGH WAS MAKING ITS WAY ACROSS THE NORTHERN PACIFIC.
AT THE SURFACE...THE SURFACE LOW HAD MOVED EAST AND WAS OVER
ILLINOIS...WITH HIGH PRESSURE OVER COLORADO. WINDS HAD SUBSIDED
OVERNIGHT AS THE PRESSURE GRADIENT RELAXED. LAPS RATES REMAINED
QUITE STEEP AS INDICATED BY LAPS SOUNDINGS ACROSS THE FORECAST
AREA WHICH HAS HELPED TO CONTINUE SOME SCATTERED SHOWERS MOVING
SOUTHEAST ACROSS THE CENTRAL PART OF THE FORECAST AREA.
OBSERVATIONS ARE INDICATING CEILINGS MAINLY AT 5K FEET AND RADAR
ECHOES ARE QUITE LIGHT AND NOT STABLE SO DON/T THINK THERE IS
MUCH/IF ANYTHING REACHING THE SURFACE.
FOR TODAY...ALTHOUGH THERE WILL BE WARM AIR ADVECTION ALOFT /ABOVE
600MB AS RIDGING SLOWLY BUILDS IN...LAPS RATES BELOW 600MB WILL
REMAIN STEEP /7-8 DEGREES PER KM/ AND AS THE SHORTWAVE OVER
ALBERTA MOVES SOUTHEAST BRINGING SOME EXTRA LIFT ACROSS THE AREA
LATER THIS MORNING AND THIS AFTERNOON...EXPECTING ISOLATED TO
SCATTERED SNOW SHOWERS MAINLY EAST OF A PINE RIDGE TO NORTH PLATTE
LINE. THERE ISN/T MUCH MOISTURE TO WORK WITH SO DON/T EXPECT
MUCH/IF ANY FOR ACCUMULATIONS. OTHER CONCERN FOR TODAY IS WINDS.
ALTHOUGH THE PRESSURE GRADIENT WON/T YIELD STRONG WINDS...THE
STEEP LAPSE RATES /GOOD MIXING/ WILL LIKELY BRING ABOUT SOME WINDY
CONDITIONS. BUFKIT FORECAST SOUNDINGS FROM THE NAM INDICATE WINDS
AT THE TOP OF THE MIXED LAYER THIS AFTERNOON OF 35 TO 45KTS. WHILE
THE GFS IS A BIT HIGHER...UP TO 50KTS AT 700MB. AS THIS ISN/T A
STRONG COLD AIR ADVECTION/SUBSIDENT REGIME...EVEN THOUGH HAVE THE
STRONG LAPSE RATES...DON/T KNOW IF THOSE WINDS WILL BE ABLE TO BE
MIXED TO THE SURFACE. DID INCREASE WINDS IN THE FORECAST...AND MAY
HAVE A FEW POINTS THAT REACH ADVISORY CRITERIA...BUT WITH
CONFIDENCE LESS THAN 50 PERCENT AND IT BEING LOW END AND NOT
WIDESPREAD OPTED TO NOT ISSUE ANY HEADLINES FOR TODAY. DAYSHIFT
CAN MONITOR IF THE WINDS INCREASE TOO MUCH AND IF AN ADVISORY WOULD
BE NEEDED.
THE TROUGH OVER THE NORTHERN PACIFIC WILL PUSH OVER THE RIDGE
TONIGHT AND SATURDAY...WITH LOW PRESSURE DEVELOPING AT THE SURFACE
ON THE LEE SIDE OF THE ROCKIES OVER MONTANA/WYOMING AND COLORADO.
THIS WILL BRING A BRIEF WINDOW OF RIDGING ACROSS THE PLAINS...WITH
WARMER TEMPERATURES EXPECTED FOR SATURDAY. THERE LOOKS TO BE
PLENTY OF SUNSHINE...BUT WITH JUST A QUICK WINDOW FOR WARMING ONLY
HAVE FORECAST HIGHS IN THE 40S TO MID 50S IN THE SOUTH. SOUTHERLY
WINDS WILL ALSO BE PRETTY BREEZY ON SATURDAY AS THE LOW PRESSURE
TO THE WEST STRENGTHENS. CURRENTLY LOOKS LIKE WINDS WILL STAY
BELOW ADVISORY CRITERIA.
THE UPPER LEVEL LOW WILL TRACK NORTH OF THE AREA /OVER THE
DAKOTAS/ AS WILL THE SURFACE LOW. THE COLD FRONT WILL PASS THE
FORECAST AREA SATURDAY NIGHT...BRINGING A WIND SHIFT...BUT LITTLE
IF ANY PRECIPITATION TO ALL BUT THE NORTHERN TIER OF COUNTIES.
DEEP MOISTURE WILL FOR THE MOST PART STAY NORTH OF THE AREA SO
WILL JUST CONTINUE THE SLIGHT CHANCES FOR SNOW OVER THE NORTHERN
COUNTIES. AGAIN...WINDY CONDITIONS ARE EXPECTED BEHIND THE COLD
FRONT WITH A FAIRLY TIGHT PRESSURE GRADIENT ACROSS SOUTH DAKOTA
AND INTO NEBRASKA THROUGH SUNDAY. STRONGEST WINDS LOOK TO BE NORTH
OF THE HIGHWAYS 2 AND 91 CORRIDOR.
LONG TERM...MONDAY THROUGH THURSDAY
THIS PERIOD ALSO LOOKS FAIRLY ACTIVE WITH A STRONG SYSTEM
PROJECTED TO MOVE ACROSS THE CENTRAL PLAINS MONDAY NIGHT THROUGH
WEDNESDAY. THE UPPER LEVEL SYSTEM WILL MOVE ONSHORE ON
MONDAY...THEN TRACK TOWARDS THE CENTRAL PLAINS MONDAY NIGHT. THE
TRACK OF THIS SYSTEM HAS TRENDED NORTH...WHICH BRINGS WARMER AIR
INTO PLAY WHICH COULD CAUSE ISSUES WITH PRECIPITATION TYPE. THE
LOW LEVEL FLOW WOULD SUGGEST A WIDE OPEN GULF WITH STRONG MOISTURE
TRANSPORT NORTHWARD. ALSO...LOOKING AT THE ISENTROPIC
SURFACES...STRONG LIFT ALONG WITH SPECIFIC HUMIDITIES OF 5 TO 6
G/KG INTO SOUTHWEST NEBRASKA INDICATE PLENTY OF JUICE FOR
PRECIPITATION. THE SURFACE LOW DEEPENS OVER EASTERN COLORADO AND A
WARM FRONT PUSHES NORTH INTO NEBRASKA MONDAY NIGHT. THE MODEL
SOLUTIONS HAVE COME INTO DECENT AGREEMENT WITH BRINGING THE WARM
AIR INTO MUCH OF THE FORECAST AREA...WHICH COULD BE WARM ENOUGH
FOR A RAIN/SNOW MIX OR JUST RAIN ACROSS SOUTHERN INTO NORTHEAST
NEBRASKA MONDAY NIGHT INTO TUESDAY. DID RAISE LOW TEMPERATURES A
BIT BUT DUE TO THE LIKELIHOOD THAT THERE WILL BE CHANGES YET AS
THE SYSTEM GETS CLOSER...DIDN/T GO TOO WARM. THE GFS IS THE
WARMEST SOLUTION WHICH WOULD SUGGEST RAIN OVER THE ENTIRE FORECAST
AREA MONDAY NIGHT INTO TUESDAY. AT THIS POINT WANT TO EXERCISE
SOME CAUTION SO JUST WENT WITH A RAIN/SNOW MIX OVER THE
SOUTHEASTERN HALF WITH SNOW OVER THE PANHANDLE AND NORTHWEST
NEBRASKA. AS THE LOW MOVES EAST...ARCTIC AIR WILL COME SOUTH ON
THE BACK SIDE OF THE SYSTEM WHICH WILL SWITCH PRECIPITATION OVER
TO ALL SNOW BY THE END OF THE DAY TUESDAY. SOMETHING ELSE TO
CONSIDER AS THERE IS COLDER AIR TO DEAL WITH...ALONG WITH A GOOD
TONGUE OF WARM AIR ABOVE THE SURFACE IS IF THERE WILL BE AN AREA
OF FREEZING RAIN OR SLEET. AS WAS STATED EARLIER...STILL NOT A
GREAT DEAL OF CONFIDENCE IN HOW THIS WILL ALL PLAY OUT SO DIDN/T
WANT TO ADD THE FREEZING PRECIPITATION TYPES INTO THE FORECAST
QUITE YET. SOMETHING TO KEEP IN MIND THOUGH.
SHOULD GET A SMALL BREAK WEDNESDAY AND WEDNESDAY NIGHT BEFORE THE
NEXT SYSTEM CROSSES THE ROCKIES ON THURSDAY...SO HAVE CHANCES FOR
PRECIPITATION AGAIN FOR THURSDAY NIGHT.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT/LONG TERM...BROOKS
AVIATION...TAYLOR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
413 PM EST FRI FEB 24 2012
.SYNOPSIS...
A STRONG COLD FRONT WILL MOVE ACROSS THE FORECAST AREA THIS
EVENING. AHEAD OF THIS COLD FRONT STRONG THUNDERSTORMS REMAIN
POSSIBLE AND A TORNADO WATCH REMAINS IN EFFECT THROUGH EARLY
EVENING. COOLER AND DRIER CONDITIONS WILL PREVAIL OVER THE
WEEKEND. A WARMING TREND IS EXPECTED THROUGH MUCH OF NEXT WEEK
AS HIGH PRESSURE MOVES OFFSHORE...AND STRONG LOW PRESSURE PASSES
NORTH OF THE REGION.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
AS OF 330 PM FRIDAY...TORNADO WATCH #38 CONTINUES ACROSS THE CWA
THROUGH 8PM TONIGHT.
SQUALL LINE WHICH HAS DEVELOPED ALONG A PREFRONTAL TROUGH IS
CURRENTLY PUSHING WEST TO EAST THROUGH THE CWA...AND WILL EXIT THE
COAST IN THE NEXT FEW HOURS. THE ENVIRONMENT REMAINS FAVORABLE FOR
DAMAGING WINDS AND ISOLATED TORNADOES...ALTHOUGH STABILIZATION IS
OCCURRING BEHIND THIS LINE. CONCERN THROUGH THE REST OF THE NIGHT
REVOLVES AROUND THIS INITIAL LINE...AND ANY STORMS THAT MAY DEVELOP
ALONG THE COLD FRONT ITSELF.
FOR THE NEXT FEW HOURS...PREFRONTAL SQUALL LINE WILL PUSH EAST. AN
OBVIOUS MARINE LAYER IS EVIDENT IN LATEST MSAS ANALYSIS...AND THIS
SHOULD HELP SQUELCH CONVECTION AS IT HEADS TOWARDS THE COAST. STILL
SIGNIFICANT SBCAPE JUST INLAND FROM THE COAST WHICH WILL SUPPORT
STORMS FOR ANOTHER HOUR OR TWO...BUT LOW LEVEL LAPSE
RATES...LI`S...AND INSTABILITY ALL DECREASE WITHIN 20 MILES OR SO OF
THE COAST. ADDITIONALLY...KLTX VWP SHOWS THAT LOW LEVEL WINDS HAVE
DECREASED SLIGHTLY TO AROUND 40 KTS AT 3 KFT. UNFORTUNATELY...HRRR
HAS BEEN DOWN...BUT LATEST RUC DIMINISHES THIS INITIAL BATCH BY 6PM
WHICH SEEMS PLAUSIBLE BASED OFF THE ONGOING ENVIRONMENT.
COLD FRONT WILL THEN APPROACH TONIGHT. THERE IS POTENTIAL FOR
RENEWED CONVECTION ALONG THE FRONT AS IT PUSHES THROUGH BETWEEN 6PM
AND 9PM. QUESTION BECOMES HOW MUCH RE-DESTABILIZATION CAN OCCUR
BEHIND THE ONGOING CONVECTION TO HELP FUEL STORMS ALONG THE FRONT.
NOTE THAT CAPE IS INCREASING ACROSS WESTERN PORTIONS OF NC AHEAD OF
THE FRONT...BUT DIURNAL HEATING WILL BE WORKING AGAINST US. WILL
KEEP CHANCE OF TSTMS THROUGH THE COLD FRONTAL PASSAGE...BUT THE
SEVERE THREAT WILL BE MINIMAL AFTER AROUND 6PM. OF COURSE...ANY
ELEVATED INSTABILITY THAT PERSISTS IN THE RESIDUAL LAYER COULD FORCE
STRONG UPDRAFTS SO WILL HAVE TO MONITOR RADAR TRENDS.
TEMPS WILL CRASH BEHIND THE FRONT TONIGHT AS GUSTY SW WINDS BECOME
GUSTY FROM THE NW. WINDS WILL CONTINUE TO GUST THROUGH MUCH OF THE
NIGHT TO 20 MPH OR SO...AND THIS WILL CAUSE TEMPS TO CRASH 20-25
DEGREES AFTER NIGHTFALL...WITH LOWS AROUND 40 INLAND...AND LOW 40S
AT THE COAST.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
AS OF 330 PM FRIDAY...BY DAYBREAK SATURDAY A VASTLY DIFFERENT FEEL
TO THE AIR WITH COLD AIR ADVECTION UNDERWAY AND CLEARING SKY TRENDS.
MAX TEMPS 57-62 SATURDAY...AND GOOD RADIATIONAL COOLING WILL ALLOW
MINS SUNDAY MORNING TO DIP TO AROUND FREEZING IN MANY INTERIOR
LOCATIONS. SUNDAY A FEW IMPULSES OUT OF THE GULF WILL BRING
INCREASING CLOUDS AND A SLIGHT CHANCE OF LIGHT SHOWERS TO OUR
SOUTHERN ZONES SUNDAY NIGHT.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
AS OF 330 PM FRIDAY...EARLY AND MID WEEK MARKED BY RIDGING ALOFT
AND SOUTHERLY WIND FLOW. RIDGE BREAKS DOWN AS AN UPPER LOW PASSES
NORTH OF THE AREA AND BRINGS THE BEST CHANCE OF SHOWERS WEDNESDAY
INTO THURSDAY...WITH ZONAL FLOW IN WAKE OF THIS FEATURE.
&&
.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
AS OF 20Z...A STRONG COLD FRONT WILL MOVE THROUGH THE TERMINALS
LATE THIS AFTERNOON AND EVENING. SHOWERS AND THUNDERSTORMS ARE
CONTINUING TO DEVELOP WEST OF FLO...AND ARE EXPANDING MORE RAPIDLY
TO THE NORTHEAST THAN EAST. WILL INDICATE PRIMARILY MVFR
CONDITIONS AT FLO/LBT THROUGH MUCH OF THIS AFTERNOON WITH
THUNDERSTORMS/TEMPO IFR LIKELY AT LEAST THROUGH MID AFTERNOON.
MVFR CONDITIONS AT THE COASTAL TERMINALS CAN BE EXPECTED LATE
AFTERNOON WITH THE SAME THUNDERSTORM/TEMPO IFR POTENTIAL LATE
AFTERNOON/EARLY EVENING. AFTER FROPA EXPECT RAPID IMPROVEMENT TO
VFR MID-LEVEL CEILINGS WITH WINDS SHIFTING TO THE NORTHWEST. BY
MIDNIGHT SKIES SHOULD BECOME SCATTERED AT FLO/LBT AND AT THE
COASTAL TERMINALS IN THE PRE-DAWN HOURS. AFTER SUNRISE EXPECT VFR
CONDITIONS WITH SCATTERED CLOUDS AND NORTHWEST WINDS GUSTING TO 25
KNOTS.
EXTENDED OUTLOOK...LOW CHANCE OF IFR/FOG EARLY MONDAY AND TUESDAY
WITH SHOWERS POSSIBLE LATER TUESDAY. OTHERWISE VFR.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 330 PM FRIDAY...SQUALL LINE APPROACHING THE WATERS WILL CREATE
SOME SCATTERED THUNDERSTORMS AND A BRIEF INCREASE IN WINDS IN THE
NEXT FEW HOURS...BUT OTHERWISE FORECAST REMAINS ON TRACK. SOUTHWEST
WINDS OF 15-25 KTS WILL PERSIST THROUGH A COLD FRONTAL PASSAGE WHICH
WILL OCCUR TONIGHT AROUND MIDNIGHT. A RATHER SIGNIFICANT WIND SHIFT
OCCURS WITH THE COLD FRONT...FROM SW TO NW...AT STILL ELEVATED
SPEEDS OF 15-25 KTS. A FEW GALE FORCE GUSTS ARE POSSIBLE...BUT NOT
EXPECTED TO BE WIDESPREAD ENOUGH TO UPGRADE THE ONGOING SCA TO
ANYTHING HIGHER. SEAS HAVE BEEN SLIGHTLY BELOW PROGS...MOSTLY 4-6
FEET...BUT WILL CONTINUE TO BUILD TO 5-8 THROUGH TONIGHT...DOMINATED
BY A SW WIND CHOP. NW WINDS BEHIND THE FRONT WILL INITIALLY CREATE A
PERIOD OF HIGHLY CONFUSED SEAS...BEFORE NW WIND CHOP BECOMES THE
PREDOMINANT WAVE AND BEGINS TO DECREASE OVERNIGHT. SMALL CRAFT
ADVISORY WILL LIKELY BE ALLOWED TO EXPIRE ACROSS THE SOUTHERN WATERS
LATE TONIGHT...BUT PERSIST ACROSS AMZ250 AND AMZ252 THROUGH THE
MORNING.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 3 PM FRIDAY...ADVISORIES EXTENDED INTO MIDDAY SATURDAY OVER
OUR NORTHERN TWO MARINE ZONES DUE TO GUSTY NW WINDS. SEAS HOWEVER
WILL BE DAMPENING AND ONCE WINDS ABATE...ADVISORIES WILL BE DROPPED.
SUNDAY IMPROVED CONDITIONS AS WINDS TAPER OFF AS HIGH PRESSURE
PASSES JUST NORTH OF THE WATERS.
LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 3 PM FRIDAY...ONSHORE
BUT LIGHT FLOW MON AND TUE WILL BECOME SOUTHERLY AND INCREASE LATE
TUESDAY THROUGH WEDNESDAY AHEAD OF A COLD FRONT EARLY THURSDAY...THUS
WE MAY BE LOOKING AT ADVISORY CONDITIONS MID WEEK.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST SATURDAY FOR
AMZ254-256.
SMALL CRAFT ADVISORY UNTIL NOON EST SATURDAY FOR AMZ250-252.
&&
$$
NEAR TERM...JDW
SHORT TERM...MJC
LONG TERM...MJC
AVIATION...MRR/SGL
AREA FORECAST DISCUSSION
NWS RALEIGH NC
320 PM EST FRI FEB 24 2012
.SYNOPSIS...
A STRONG COLD FRONT WILL CROSS THE REGION LATER TODAY. STRONG
SOUTHWESTERLY WINDS AND THE POTENTIAL FOR SEVERE WEATHER WILL
ACCOMPANY THE FRONT THIS AFTERNOON THROUGH MID EVENING. COOLER AND
DRIER CONDITIONS ARE EXPECTED BEHIND THE COLD FRONT FOR THE WEEKEND.
&&
.NEAR TERM /THROUGH SATURDAY NIGHT/...
AS OF 310 PM FRIDAY...
...MODERATE RISK OF SEVERE WEATHER WITH DAMAGING WINDS AND POSSIBLE
TORNADOES TODAY...
THROUGH THIS EVENING: THE SURFACE COLD FRONT ACCORDING TO THE LATEST
MESOANALYSIS HAS PUSHED WELL INTO THE NC MOUNTAINS. STRONG TO SEVERE
CONVECTION CONTINUES TO STREAK ACROSS SOUTHEAST NC... SUPPORTED IN
LARGE PART BY A LOW LEVEL JET STREAK AND ASSOCIATED MASS
CONVERGENCE. WITH EARLY-DAY SURFACE HEATING COMBINED WITH WEAK MID
LEVEL COOLING... THE COLUMN CONTINUES TO DESTABILIZE WITH SURFACE
CAPE ESTIMATED TO BE AROUND 400-1000 J/KG ACROSS THE AREA (AND
MEASURED AT AROUND 400 J/KG ON THE SPECIAL 18Z GSO SOUNDING)...
ALTHOUGH THE BLOWOFF FROM THESE SOUTHEAST STORMS AND FROM EARLIER
SC/GA CONVECTION HAS SPREAD ACROSS EAST-CENTRAL NC AND TEMPERED THE
INSTABILITY A BIT HERE... DESPITE SURFACE DEW POINTS WELL INTO THE
60S. THE INTENSE WIND FIELD (0-6 KM SHEAR NEAR 70 KTS AND 0-1 KM
SHEAR OF AROUND 40 KTS) WILL REMAIN SUPPORTIVE OF ORGANIZED SEVERE
CONVECTION... AND WE HAVE INDEED SEEN THESE DISCRETE CELLS AND
BOWING SEGMENTS BECOME MORE ORGANIZED OVER THE WESTERN PIEDMONT...
JUST A BIT AHEAD OF THE FRONT... IN THE LAST HOUR. FURTHER
DEVELOPMENT INTO A MATURE QLCS SHOULD BRING A WIDESPREAD THREAT OF
DAMAGING WINDS FOR THE REST OF THE AFTERNOON INTO EARLY EVENING.
ISOLATED TORNADOES REMAIN POSSIBLE GIVEN THE NICELY CURVED HODOGRAPH
THROUGH THE LOWEST 3 KM NOTED ON RUC PROXIMITY SOUNDINGS... AND DEEP
MOISTURE (BLENDED TPW IMAGERY SHOWING VALUES AROUND 200% OF NORMAL)
WITH HIGH DEW POINTS SHOULD ENSURE SUFFICIENTLY LOW LCL HEIGHTS FOR
A POSSIBLE STRONG TORNADO OR TWO. A TORNADO WATCH REMAINS IN EFFECT
UNTIL 8 PM FOR ALL OF CENTRAL NC. EXPECT THE SURFACE FRONT AND
PRECEDING STORMS TO SWEEP EAST OF THE FORECAST AREA BY MID
EVENING... FOLLOWED BY FAIR SKIES AND FALLING TEMPS OVERNIGHT. LOWS
34-42 WITH THE LOWER TROPOSPHERE REMAINING WINDY AND WELL-MIXED
OVERNIGHT WITH COLD AIR ADVECTION.
FOR SATURDAY/SATURDAY NIGHT: THE MID LEVEL LOW TRACKING OVER LAKES
ERIE/ONTARIO AND UP THE ST LAWRENCE VALLEY OVERNIGHT WILL MOVE TO
THE CANADIAN MARITIMES SATURDAY... AS THE MID LEVEL TROUGH AXIS
SHIFTS OVER NC. THE MSLP GRADIENT REMAINS QUITE TIGHT SUCH THAT
WINDS WILL INCREASE ANEW AFTER SUNRISE TO SUSTAINED 17-23 MPH WITH
GUSTS TO AROUND 30-35 MPH... LASTING THROUGH EARLY AFTERNOON BEFORE
SLOWLY DIMINISHING AS THE LARGE SURFACE HIGH BUILDS IN FROM THE
WEST. THESE WINDS COMBINED WITH LOW RELATIVE HUMIDITY VALUES WILL
BRING ABOUT A RISK OF ADVERSE FIRE WEATHER CONDITIONS (SEE
DISCUSSION BELOW). STRONG LOW LEVEL COLD AIR ADVECTION AND UPSTREAM
TEMPS TODAY POINT TO HIGHS OF 52-58 SATURDAY... UNDER MOSTLY SUNNY
SKIES. CLEAR SATURDAY NIGHT WITH CHILLY LOWS OF 25-30 AS WINDS
DIMINISH TO NEARLY CALM DURING THE NIGHT. -GIH
&&
.SHORT TERM /SUNDAY THROUGH MONDAY/...
AS OF 120 PM FRIDAY...
THE SOUTHERN STREAM WAVE OVER MEXICO WILL LIFT NORTHEASTWARD AND
DEAMPLIFY ACROSS THE CAROLINAS ON SUNDAY. SINCE STABLE SURFACE HIGH
PRESSURE (~1030-1035 MB) WILL PREVAIL DURING THAT TIME...EXPECT ONLY
CONSIDERABLE HIGH CLOUDINESS IN ASSOCIATION WITH THE WAVE ALOFT.
HIGH TEMPERATURES...ADJUSTED DOWN SEVERAL DEGREES FROM THE PREVIOUS
FORECAST...ARE EXPECTED TO RISE TO WITHIN A DEGREE OR TWO OF 50
DEGREES. HIGH PRESSURE WILL THEN DRIFT OFFSHORE BUT CONTINUE TO
EXTEND WESTWARD ACROSS NC AND MAINTAIN FAIR WEATHER THROUGH EARLY
NEXT WEEK. GOOD RADIATIONAL COOLING WITH PROJECTED LOW LEVEL
THICKNESSES AROUND 1320 METERS SUGGESTS LOWS IN THE UPPER 20S TO
LOWER 30S...WHILE DEVELOPING RETURN FLOW BY LATE MON SHOULD ALLOW
TEMPERATURES TO CLIMB INTO THE LOWER TO MIDDLE 60S.
&&
.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 145 PM FRIDAY...
MON NIGHT-TUE NIGHT: A LOW LEVEL WARM ADVECTION REGIME WILL SUPPORT
INCREASING MOISTURE IN THE LOWEST 10 THOUSAND FT LATE MON NIGHT AND
ESPECIALLY TUE...WHICH WILL PROVIDE FOR INCREASING CLOUDINESS...AND
A CHANCE OF SHOWERS MAINLY OVER THE SOUTHERN AND WESTERN PORTIONS OF
THE CWFA TUE...AND AREA-WIDE WITH A WARM FRONTAL PASSAGE TUE NIGHT.
TEMPERATURES WILL ACCORDINGLY FURTHER MODERATE - MIDDLE 30S TO
AROUND 40 DEGREES MON NIGHT...MIDDLE 60S TUE...AND MOSTLY PRIOR TO
MIDNIGHT LOWS IN THE MIDDLE 40S TO LOWER 50S (COOLEST NE) COURTESY
OF THE PASSING WARM FRONT.
WED-FRI: A PAIR OF UPPER TROUGHS...IN A PROGRESSIVE UPPER FLOW
PATTERN ACROSS THE CONUS...WILL SUPPORT A COUPLE OF MIGRATORY
SURFACE CYCLONES TO OUR NW (MUCH LIKE THE MAJORITY OF THIS WINTER
WEATHER SEASON) OWING TO A PERSISTENT 588 DM SUB-TROPICAL RIDGE OVER
THE CARIBBEAN. GUIDANCE SUGGESTS THE FRONT TRAILING THE FIRST
CYCLONE WILL CROSS THE MIDDLE ATLANTIC REGION WITH A GOOD CHANCE OF
SHOWERS (AND PERHAPS A FEW STORMS DUE TO THE PRECEDING WARMTH IN THE
70S) WED INTO WED NIGHT. CLEARING AND TURNING COOLER...BUT STILL
ABOVE AVERAGE...FOR THU-THU NIGHT...BEFORE THE THE SECOND FRONTAL
SYSTEM BRINGS ANOTHER THREAT OF SHOWERS BY THE END OF THE WORK WEEK.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 105 PM FRIDAY...
WITH A COMBINATION OF STRONG GUSTY WINDS AND A PERIOD OF STRONG TO
POSSIBLY SEVERE STORMS AHEAD OF AN INCOMING COLD FRONT... ADVERSE
AVIATION CONDITIONS ARE LIKELY AT CENTRAL NC TERMINAL FORECAST SITES
THIS AFTERNOON INTO EARLY EVENING... FIRST AT INT/GSO 18Z-22Z...
THEN AT RDU 19Z-23Z... AND AT RWI AT 20Z-00Z. FAY WILL SEE AN
EXTENDED THREAT OF STORMS FROM 18Z THROUGH 00Z AS STORMS TRAIN
REPEATEDLY OVER THE AREA. BACKGROUND WINDS FROM THE SW SUSTAINED AT
16-23 KTS WILL OCCASIONALLY GUST TO 25-35 KTS OUTSIDE OF ANY
STORMS... AND THIS STRONG WIND SHEAR IN THE LOWEST FEW THOUSAND FEET
MAY INDUCE MECHANICAL TURBULENCE THAT COULD BE HAZARDOUS ESPECIALLY
TO SMALL AIRCRAFT. NOTE THAT THESE PREFRONTAL WIND IS A STRONG
CROSSWIND AT INT. STRONG TO POSSIBLY SEVERE STORMS COULD BRING LOCAL
WIND GUSTS IN EXCESS OF 60 KTS WITH A LESSER THREAT OF HAIL THROUGH
THE REST OF THE AFTERNOON INTO EARLY EVENING. ISOLATED TORNADOES ARE
ALSO POSSIBLE. DOMINANT VFR CIGS/VSBYS WILL DROP TO MVFR AND IFR IN
AND NEAR SHOWERS/STORMS. THE RISK OF STORMS WILL BE OVER BY
22Z-02Z... HOWEVER WITH COLD FRONTAL PASSAGE THE WINDS WILL SHIFT
AROUND TO WNW (270-300 DEGREES) AND REMAIN STRONG THROUGH THE NIGHT
AT 10-20 KTS PERIODICALLY GUSTING TO 20-25 KTS. MAINLY WESTERLY
WINDS WILL PICK BACK UP SATURDAY MORNING AT 15-20 KTS SUSTAINED AND
GUSTING TO 25-30 KTS. VFR CONDITIONS ARE EXPECTED FROM MID EVENING
THROUGH SATURDAY.
LOOKING BEYOND EARLY SATURDAY AFTERNOON: WINDS WILL DIMINISH BY 22Z
SATURDAY. MVFR/IFR FOG/STRATUS IS POSSIBLE TUESDAY MORNING INTO
WEDNESDAY IN ASSOCIATION WITH AN APPROACHING FRONTAL SYSTEM.
STRENGTHENING WINDS FROM THE SW ARE ALSO POSSIBLE WEDNESDAY. -GIH
&&
.FIRE WEATHER...
AS OF 140 PM FRIDAY...
...RED FLAG WATCH FOR SATURDAY AFTERNOON FOR NORTHWEST PIEDMONT...
STRONG GUSTY SOUTHWEST WINDS OF 35 TO 40 MPH AHEAD OF A COLD FRONT
WILL SHIFT TO WEST NORTHWEST LATE THIS AFTERNOON AND EVENING IN THE
WAKE OF THE EXITING FRONT. TEMPERATURES OUTSIDE SHOWERS ARE IN THE
MID TO UPPER 70S THIS AFTERNOON. LOWEST RELATIVE HUMIDITIES WILL BE
MODEST... FALLING NO LOWER THAN 35 PERCENT THIS EVENING BEFORE
RISING OVERNIGHT. RAINFALL WILL BE SPOTTY IN THE WEST... WITH
WIDESPREAD RAINS IN THE EAST OF AS MUCH AS ONE INCH. SCATTERED
THUNDERSTORMS ARE FORECAST... MAINLY EAST.
BREEZY WEST NORTHWEST WINDS 15 TO 20 MPH WITH GUSTS OF 30 TO 35 MPH
ARE EXPECTED BY MID MORNING SATURDAY... CONTINUING INTO THE
AFTERNOON. MINIMUM RELATIVE HUMIDITIES WILL FALL TO 15 TO 25
PERCENT. HOWEVER IT WILL BE MUCH COOLER WITH HIGHS IN THE 50S.
A RED FLAG WATCH WILL BE ISSUED FOR MUCH OF WESTERN NORTH CAROLINA
WEST OF HIGHWAY 220. ANY POSSIBLE RED FLAG WATCH WILL BE ADJUSTED
SATURDAY MORNING BASED ON RAINFALL FALLING THIS AFTERNOON.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
FIRE WEATHER WATCH FROM SATURDAY MORNING THROUGH SATURDAY EVENING
FOR NCZ007-021>023-038-039-073.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...HARTFIELD
SHORT TERM...MWS
LONG TERM...MWS
AVIATION...HARTFIELD
FIRE WEATHER...99
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
345 PM MST FRI FEB 24 2012
.DISCUSSION...THE STRONG LOW PRESSURE SYSTEM CROSSING THE NORTHERN
PLAINS ON SUNDAY WILL PRODUCE WEST TO NORTHWEST WINDS OF 25 TO 40
MPH WITH WIND GUSTS UP TO 55 MPH. HAVE ISSUED A WIND ADVISORY FOR
THE NORTHWEST AND WEST CENTRAL SOUTH DAKOTA PLAINS.
&&
.PREV DISCUSSION... /ISSUED 240 PM MST FRI FEB 24 2012/
DISCUSSION...
LONG WAVE RIDGE NEAR 130W AND TROF NEAR 95W WITH CONTINUED FLOW OF
COOL...UNSTABLE AIR OVER THE AREA TODAY. SHORT WAVE RIDGE
APPROACHING FROM THE WEST FORECAST TO BE OVER THE AREA FRIDAY
NIGHT AND EARLY SATURDAY. NEXT UPSTREAM TROF WILL CROSS THE
PACIFIC NW COAST LATE TONIGHT AND MOVE QUICKLY EAST WARD.
STEEP LAPSE RATES AND A BIT OF MID TROPOSPHERIC Q VECTOR
CONVERGENCE HAVE SUPPORTED THE DEVELOPMENT OF SNOW SHOWERS AGAIN
TODAY. MID AFTERNOON RADAR AND SATELLITE OBS INDICATE THESE ARE
FINALLY WINDING DOWN AS SUBSIDENCE WARMING FORECAST BY BOTH THE
NAM AND RUC MODELS SEEMS TO BE HAPPENING. REMNANT CLOUDS AND A
LITTLE PRECIP WILL PERSIST INTO THE EVENING HOURS OVER UPSLOPE
AREAS OF THE BLACK HILLS. A FEW SHOWERS ARE LIKELY TO RETURN TO NW
WY AND THE NW PORTIONS OF SD WITH APPROACH OF NEXT SHORT WAVE TROF.
NAM AND MESO MODELS INDICATE POTENTIAL FOR FAIRLY STRONG DOWNSLOPE
WINDS OVER THE NE SLOPES OF THE BLACK HILLS SATURDAY MORNING INTO
EARLY AFTERNOON. MODELS INDICATE ABOUT A 6MB PRESSURE DIFFERENCE
ACROSS THE HILLS AT 18Z AND THE NAM FORECAST SOUNDINGS SHOW 50KT
WINDS AT ABOUT 2000FT AGL OVER THE NORTHERN BLACK HILLS.
SATURDAY NIGHT...TRANSIENT UPPER RIDGE SHIFTS QUICKLY EAST AS NEXT
STRONG UPPER SHORTWAVE CROSSES THE NORTHERN ROCKIES. BOTH 500MB AND
700MB CLOSED LOWS TRACK NORTH OF THE FORECAST AREA...WITH BEST
CHANCES OF SNOW ACROSS NORTHEAST WYOMING...THE BLACK HILLS...AND
NORTHWESTERN SOUTH DAKOTA AS COLD FRONT MOVES THROUGH. BEST CHANCES
OF ACCUMULATING SNOWS WILL BE ACROSS THE NORTHERN BLACK HILLS. LOW
TEMPERATURES WILL FALL INTO THE TEENS AND 20S.
SUNDAY...UPPER LOW SLIDES INTO MINNESOTA AS BOUNDARY LAYER FLOW
BECOMES MORE WEST TO NORTHWEST. PRECIP CHANCES DIMINISH QUICKLY ON
SUNDAY MORNING...BUT VERY WINDY CONDITIONS WILL BE FOUND BEHIND THE
EXITING LOW ACROSS THE AREA. WINDS IN EXCESS OF 25 TO 35 MPH WITH
HIGHER GUSTS WILL BE POSSIBLE. HIGH TEMPERATURES WILL BE IN THE 30S
TO LOWER 40S.
EXTENDED...POTENTIAL FOR A STRONG WINTER STORM TO AFFECT THE AREA
EARLY NEXT WEEK. GFS/GEFS/ECMWF IN VERY GOOD AGREEMENT
MONDAY/TUESDAY WITH UPPER TROF SWINGING THROUGH THE CENTRAL ROCKIES
AND INTO THE PLAINS. GFS/GEFS/ECMWF SFC-500MB LOW TRACKS
SIMILAR...ACROSS WESTERN NEBRASKA TO SOUTHEAST SOUTH
DAKOTA/NORTHWEST IOWA. EVEN THOUGH TRACK IS SIMILAR...THERE IS
SOME STRENGTH AND TIMING DIFFERENCES. ALL GEFS MEMBERS SHOW
MEASURABLE PRECIPITATION ACROSS NORTHEAST WYOMING AND WESTERN
SOUTH DAKOTA MONDAY NIGHT/TUESDAY. GIVEN HIGHER MODEL
CONFIDENCE...HAVE BOOSTED POPS FOR MONDAY NIGHT/TUESDAY. WIND
COULD ALSO BE A BIG FACTOR DEPENDING ON STRENGTH OF SURFACE LOW.
UPPER LOW DEPARTS THE AREA WEDNESDAY...WITH FLAT UPPER RIDGE
ACROSS THE NORTHERN HIGH PLAINS. NEXT UPPER TROF TO AFFECT THE
AREA THURSDAY.
AVIATION...18Z TAFS
SCATTERED SNOW SHOWERS WILL CONTINUE ACROSS THE AREA THROUGH THIS
AFTERNOON...WITH IFR VSBY. VFR CONDITIONS EXPECTED
OVERNIGHT...WITH GUSTY SOUTHWEST WINDS DEVELOPING ACROSS NORTHEAST
WYOMING AND THE BLACK HILLS.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WIND ADVISORY FROM 8 AM TO 5 PM MST SUNDAY FOR BUTTE-HAAKON-
HARDING-NORTHERN FOOT HILLS-NORTHERN MEADE CO PLAINS-
PENNINGTON CO PLAINS-PERKINS-RAPID CITY-SOUTHERN MEADE CO
PLAINS-STURGIS/PIEDMONT FOOT HILLS-ZIEBACH.
WY...NONE.
&&
$$
SHORT TERM...15
LONG TERM....07
AVIATION...07
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
240 PM MST FRI FEB 24 2012
.DISCUSSION...
LONG WAVE RIDGE NEAR 130W AND TROF NEAR 95W WITH CONTINUED FLOW OF
COOL...UNSTABLE AIR OVER THE AREA TODAY. SHORT WAVE RIDGE
APPROACHING FROM THE WEST FORECAST TO BE OVER THE AREA FRIDAY
NIGHT AND EARLY SATURDAY. NEXT UPSTREAM TROF WILL CROSS THE
PACIFIC NW COAST LATE TONIGHT AND MOVE QUICKLY EAST WARD.
STEEP LAPSE RATES AND A BIT OF MID TROPOSPHERIC Q VECTOR
CONVERGENCE HAVE SUPPORTED THE DEVELOPMENT OF SNOW SHOWERS AGAIN
TODAY. MID AFTERNOON RADAR AND SATELLITE OBS INDICATE THESE ARE
FINALLY WINDING DOWN AS SUBSIDENCE WARMING FORECAST BY BOTH THE
NAM AND RUC MODELS SEEMS TO BE HAPPENING. REMNANT CLOUDS AND A
LITTLE PRECIP WILL PERSIST INTO THE EVENING HOURS OVER UPSLOPE
AREAS OF THE BLACK HILLS. A FEW SHOWERS ARE LIKELY TO RETURN TO NW
WY AND THE NW PORTIONS OF SD WITH APPROACH OF NEXT SHORT WAVE TROF.
NAM AND MESO MODELS INDICATE POTENTIAL FOR FAIRLY STRONG DOWNSLOPE
WINDS OVER THE NE SLOPES OF THE BLACK HILLS SATURDAY MORNING INTO
EARLY AFTERNOON. MODELS INDICATE ABOUT A 6MB PRESSURE DIFFERENCE
ACROSS THE HILLS AT 18Z AND THE NAM FORECAST SOUNDINGS SHOW 50KT
WINDS AT ABOUT 2000FT AGL OVER THE NORTHERN BLACK HILLS.
SATURDAY NIGHT...TRANSIENT UPPER RIDGE SHIFTS QUICKLY EAST AS NEXT
STRONG UPPER SHORTWAVE CROSSES THE NORTHERN ROCKIES. BOTH 500MB AND
700MB CLOSED LOWS TRACK NORTH OF THE FORECAST AREA...WITH BEST
CHANCES OF SNOW ACROSS NORTHEAST WYOMING...THE BLACK HILLS...AND
NORTHWESTERN SOUTH DAKOTA AS COLD FRONT MOVES THROUGH. BEST CHANCES
OF ACCUMULATING SNOWS WILL BE ACROSS THE NORTHERN BLACK HILLS. LOW
TEMPERATURES WILL FALL INTO THE TEENS AND 20S.
SUNDAY...UPPER LOW SLIDES INTO MINNESOTA AS BOUNDARY LAYER FLOW
BECOMES MORE WEST TO NORTHWEST. PRECIP CHANCES DIMINISH QUICKLY ON
SUNDAY MORNING...BUT VERY WINDY CONDITIONS WILL BE FOUND BEHIND THE
EXITING LOW ACROSS THE AREA. WINDS IN EXCESS OF 25 TO 35 MPH WITH
HIGHER GUSTS WILL BE POSSIBLE. HIGH TEMPERATURES WILL BE IN THE 30S
TO LOWER 40S.
EXTENDED...POTENTIAL FOR A STRONG WINTER STORM TO AFFECT THE AREA
EARLY NEXT WEEK. GFS/GEFS/ECMWF IN VERY GOOD AGREEMENT
MONDAY/TUESDAY WITH UPPER TROF SWINGING THROUGH THE CENTRAL ROCKIES
AND INTO THE PLAINS. GFS/GEFS/ECMWF SFC-500MB LOW TRACKS
SIMILAR...ACROSS WESTERN NEBRASKA TO SOUTHEAST SOUTH
DAKOTA/NORTHWEST IOWA. EVEN THOUGH TRACK IS SIMILAR...THERE IS
SOME STRENGTH AND TIMING DIFFERENCES. ALL GEFS MEMBERS SHOW
MEASURABLE PRECIPITATION ACROSS NORTHEAST WYOMING AND WESTERN
SOUTH DAKOTA MONDAY NIGHT/TUESDAY. GIVEN HIGHER MODEL
CONFIDENCE...HAVE BOOSTED POPS FOR MONDAY NIGHT/TUESDAY. WIND
COULD ALSO BE A BIG FACTOR DEPENDING ON STRENGTH OF SURFACE LOW.
UPPER LOW DEPARTS THE AREA WEDNESDAY...WITH FLAT UPPER RIDGE
ACROSS THE NORTHERN HIGH PLAINS. NEXT UPPER TROF TO AFFECT THE
AREA THURSDAY.
&&
.AVIATION...18Z TAFS
SCATTERED SNOW SHOWERS WILL CONTINUE ACROSS THE AREA THROUGH THIS
AFTERNOON...WITH IFR VSBY. VFR CONDITIONS EXPECTED
OVERNIGHT...WITH GUSTY SOUTHWEST WINDS DEVELOPING ACROSS NORTHEAST
WYOMING AND THE BLACK HILLS.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
SHORT TERM...15 AND BARBER
LONG TERM....07
AVIATION...07