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January 17-19th Plains/MW/Lakes Storm Potential Part II


Powerball

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I just did a deeper inspection on the GFS.

It's mostly a cold rain for everyone (and VERY marginal for the NW fringes), the 925mb temps are safely above zero in areas where the precipitaiton is falling, and by the time they suficiently cool off the precipitation would have ended.

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I just did a deeper inspection on the GFS.

It's mostly a cold rain for everyone (and VERY marginal for the NW fringes), the 925mb temps are safely above zero in areas where the precipitaiton is falling, and by the time they suficiently cool off the precipitation would have ended.

Theres a possibility to be surprised in a good or bad way with this system, but count me in the camp of those who will consider this storm a win if the snowpack damage is minimal. If we do get backside accumulation (which is definitely possible), its a bonus.

Also, wanted to respond to a post of yours in the locked storm thread..."Let's face it, most areas in the SE of Wisconsin-Iowa-Kansas (in the Midwest) have yet to see a storm produce more than 6" this season. In fact, the same outlined region has had two season back to back filled with nothing but nickel & dime events, so surely it's only fair to expect some frustration with this pattern we've been stuck in." Assuming you are referring much of the above to Detroit, that is COMPLETELY untrue. I know I sometimes get repetitive, but its necessary to know climo to understand some stuff. The snowy winters of 2007-08/08-09 seem to have not only spoiled many but have them forgetting whats "normal".

What is your definition of "nothing but nickel and dime"?

2009-10 at DTW

8.6" on Feb 9/10 = warning criteria

6.9" on Feb 21/22 = warning criteria

4.9" on Jan 7/8 = highend advisory criteria

2010-11 at DTW so far

6.3" on Dec 11/12 = warning criteria

5.3" on Jan 11/12 = highend advisory criteria

My point is...we are not going to get constant snowstorms, in fact its been 4 years since weve seen a below normal snowfall winter. Though I do believe one (biggest of the season) is still coming this winter. I cant tell you what to like and what not to like, lets just say that a cold, white winter like this is not one for a winter lover to hate (unless youre into just getting a storm and dont care about freaquent snowfall or snowcover...then the EC would be a better fit for you lol)

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Morning AFDs

DTX still looks to be questioning the depth/strength of the warmth due to current snowpack, also mentioning of icing concerns.

AN AMPLIFYING TROUGH OVER THE EASTERN ONE THIRD OF THE CONTIGUOUS UNITED STATES AND HEIGHT FALLS IN ADVANCE OF A STRONG N. CANADIAN PV ANOMALY WILL SEND AN ELONGATED AREA OF WEAK LOW PRESSURE (1004 MB) THROUGH LOWER MICHIGAN TONIGHT AND TUESDAY. IN GENERAL...THIS WILL BE A SYSTEM VOID OF ANY STRONG GOVERNING DYNAMICS...LARGELY OWING TO A LACK OF LOCAL BAROCLINICITY DUE TO SPLIT BRANCHES OF THE POLAR JET. THE FORECAST DECISION TONIGHT WILL BE PRECIPITATION TYPE AS ALL MODEL SOLUTIONS SUGGEST A FAIRLY DEEP LAYER OF 0 TO +2C AIR WILL LIFT NORTHWARD INTO THE CWA. THIS IS NOT A TYPICAL WARM CONVEYOR TYPE SETUP...BUT RATHER A NORTHWARD TRANSPORT OF A SFC-4 KFT LAYER DUE TO STRONG GRADIENT FLOW. THUS...A MODERATION OF THIS AIRMASS IS EXPECTED AS IT MOVES NORTHWARD DUE TO NEGATIVE HEAT FLUXES FROM THE COLD TERRESTIAL SFC. THEREFORE...CONFIDENCE IS LOW FOR THE MODEL PARAMETRIZATIONS TO GET IT CORRECT...ALL MAKING FOR A SENSITIVE FORECAST. MAIN PUSH OF 285K ISENTROPIC LIFT AND 925-850 MB THETA E ADVECTION WILL PUSH INTO THE AREA FROM THE SOUTH AND WEST AT THE START OF THE PERIOD. FORECAST SOUNDINGS SUGGEST THAT A BRIEF PERIOD OF SNOW WILL BE POSSIBLE BEFORE PTYPE WILL RAPIDLY CHANGE OVER TO A RAIN/SNOW/ICE GRAIN MIX. A COLD SURFACE AND DEWPOINTS LINGERING IN THE UPPER 20S WILL ALLOW FOR THE RAIN TO FREEZE AT THE SURFACE. QPE TONIGHT IS EXPECTED TO REMAIN AT A .10 OF AN INCH OR LESS. FARTHER NORTH...THE PRECIPITATION IS EXPECTED TO REMAIN AT ALL SNOW/SNOWGRAINS. THE EARLIER START TO THE SNOW THIS EVENING...WITH SNOW RATIOS OF AROUND 10:1 SUPPORTS SNOWFALL ACCUMULATIONS TONIGHT RANGING FROM 1 TO 2 INCHES NORTH OF M 46 TO LESS THAN AN INCH FOR THE I 69 CORRIDOR. WEAK ISENTROPIC LIFT TUESDAY WILL CONTINUE TUESDAY MORNING BEFORE GIVING WAY TO A DECENT BOUT OF 850-700 MB FRONTOGENESIS TUESDAY AFTERNOON. DIFFICULT TO SAY EXACTLY HOW LONG MIXED PRECIPITATION WILL HOLD DURING THE MORNING. MODELS SUGGEST TEMPS WILL CREEP ABOVE FREEZING RIGHT AWAY...BUT THAT IS LIKELY TOO OPTIMISTIC. PRECIPITATION AMOUNTS WILL REMAIN LIGHT ON THE LIGHT SIDE SO THAT WILL LIMIT THE GLAZING POTENTIAL. MODELS HAVE ALSO COME IN DISTINCTLY COOLER WITH THIS SYSTEM ON TUESDAY...AND HAVE TRENDED MORE TO A SNOW MENTION FOR THE AFTERNOON. THE SWATCH OF 850-700MB FGEN WHICH CONTINUES TO BE ADVERTISED BY VARYING MODEL SOLUTIONS WILL ALLOW FOR LIGHT ACCUMULATIONS OF SNOW 18-00Z FOR ALL AREAS. AN ADDITIONAL 1 TO 2 INCHES OF SNOWFALL WILL BE POSSIBLE DURING THE TUESDAY PERIOD NORTH OF I 69.

GRR also has precip concerns with a solid snow event to the north.

MAIN CHALLENGE IN THE SHORT TERM IS DETERMINING PCPN TYPE AND AMOUNTS OF EACH TYPE WITH THE SET OF WAVES THAT WILL BE MOVING IN ACROSS THE REGION LATER TODAY THROUGH TUE. AFTER COLLABORATING WITH SURROUNDING OFFICES...WE WILL BE HOLDING OFF ON HEADLINES FOR THIS FCST PACKAGE TO ALLOW THE DAY SHIFT TO TAKE ONE LAST LOOK AT TRENDS WITH THE THERMAL PROFILES. THIS EVENT STILL APPEARS TO BE HEADING TOWARD AN ADVISORY FOR MOST OF THE CWFA. MODELS ARE COMING INTO GOOD AGREEMENT REGARDING THE NEXT 36 HOURS AS LOWER MICHIGAN WILL BE AFFECTED BY A COUPLE OF SHORT WAVE TROUGHS. THE FIRST OF THESE WAVES IS NOW MOVING INTO THE MN/IA AREA. THIS WAVE WILL BE RESPONSIBLE FOR INITIATING SNOW ACROSS THE NW HALF OF THE CWFA THIS AFTERNOON. THIS WAVE DOES LOOK TO BRING A DECENT BURST OF SNOW LATE THIS AFTERNOON AND EVENING. THIS WAVE WILL BE JUST EXITING TO THE NE...AND THE NEXT WAVE DIVING INTO MT THIS MORNING WILL BE APPROACHING THE AREA. THIS WILL THEN HELP TO SPREAD PCPN FARTHER S AND E ACROSS THE REMAINDER OF THE CWFA. MODELS ARE IN GOOD AGREEMENT IN BRINGING A 3 TO 5 INCH EVENT TO ROUGHLY THE NRN THIRD OF THE CWFA. QPF WILL BE ON THE ORDER OF A THIRD TO HALF AN INCH OF WATER...HOWEVER SNOW RATIOS WILL BE RELATIVELY LOW AROUND 10-1 OR SO ON AVERAGE UP NORTH WITH THE WARMER AIR ALOFT ADVECTING IN. SNOW AMOUNTS WILL TAPER OFF AS YOU HEAD SOUTH WITH QPF A LITTLE LESS AWAY FROM THE FIRST WAVE...SNOW RATIOS A LITTLE LOWER...AND PCPN TRANSITIONING OVER TO A MIXTURE OF PCPN TYPES. WARMER AIR ALOFT WILL MOVE IN FROM SW TO NE AFTER 00Z SOUTH OF ROUGHLY A GRAND HAVEN TO MT. PLEASANT LINE. THIS WILL TRANSITION PCPN TYPE FROM SNOW TO SLEET ACROSS THE CENTRAL COUNTIES...AND FROM SNOW TO SLEET/FREEZING RAIN/RAIN ACROSS THE SRN COUNTIES BY 12Z TUE. BY 12Z...THE WARM WEDGE ALOFT DISAPPEARS FOR THE MOST PART...AND PCPN TYPE WILL BE EITHER SNOW OR RAIN. AREAS NORTH OF A SOUTH HAVEN TO LANSING LINE WILL LIKELY SEE THE MELTING LAYER TOO THIN TO SEE RAIN. SOUTH OF THAT LINE...THE MELTING LAYER WILL BE THICK ENOUGH FOR RAIN...BUT SFC TEMPS MAY STAY RIGHT AROUND FREEZING WITH THE SNOWPACK AND RECENT EXTENDED PERIOD OF COLD WEATHER THAT HAS BEEN IN PLACE. PCPN WILL THEN TRANSITION TO ALL SNOW FOR THE ENTIRE AREA AROUND OR JUST AFTER 18Z. PCPN WILL STILL BE OCCURRING...ESPECIALLY OVER THE SE CORNER OF THE CWFA WITH THE DEFORMATION ZONE OF THE SECOND TROUGH CLIPPING THAT AREA. ANY PCPN WILL BE RELATIVELY LIGHT WITH ADDITIONAL SNOW ACCUMS REMAINING AROUND AN INCH OR LESS.

IWX certainly talking up the ice potential and concerns of models overdoing surface temps.

PRECIPITATION TYPE AND CRITICAL NEAR SURFACE TEMPERATURES ARE THE MAIN CONCERNS IN THE SHORT TERM PERIOD. SHORT WAVE CROSSING THE NORTHERN PLAINS THIS MORNING WILL DIVE TOWARD OUR AREA TODAY AND TONIGHT. LOW LEVEL JET WILL INCREASE TODAY IN RESPONSE WITH WARM AIR ADVECTION ACROSS THE REGION THROUGH TONIGHT. THERMAL PROFILES SHOW WARM AIR MOVING OVER TOP COLD NEAR SURFACE LAYER WHICH WILL LEAD TO A MIXED BAG OF PRECIPITATION. WARM AIR ADVECTION WILL LEAD TO ASCENT THIS AFTERNOON WITH LOW LEVEL THETA E INCREASING. SOUNDINGS SUGGEST INITIAL PCPN TYPE WILL BE SNOW WITH SOME SLEET POSSIBLE. WARMING THIS EVENING OVER NEAR SURFACE COLD WEDGE SHOULD ALLOW FOR PCPN TO CHANGE TO LIGHT FREEZING RAIN FROM SOUTHWEST TO NORTHEAST. THE TRICKY PART OF THE FORECAST IS SURFACE TEMPERATURES WHICH WILL OBVIOUSLY DICTATE WHEN FREEZING RAIN BECOMES JUST RAIN. MODELS ALL IN RATHER GOOD AGREEMENT ON 2M TEMPS WARMING TO BETWEEN 32 AND 34 DEGREES ACROSS MOST OF THE AREA OVERNIGHT. STILL HAVE REASONABLE CONCERN THAT MODELS ARE TOO AGGRESSIVE WITH THIS WARMING OVER THE SNOWPACK AND FROZEN GROUND WHICH HAS BEEN IN PLACE FOR SOME TIME NOW AND BEING REINFORCED THIS MORNING WITH TEMPERATURES IN THE SINGLE DIGITS AND TEENS. HAVE LEANED TOWARD THE NAM/SREF SOLUTIONS GIVEN THEIR RESOLUTION AND TRIED TO USE THEIR THERMAL PROFILES AND THICKNESS SCHEMES FOR PCPN TYPE AND CHANGEOVER. GRIDS BECOME QUITE MESSY WITH RESPECT TO THIS COUPLED WITH ATTEMPT TO COLLABORATE. BASICALLY EXPECT PCPN TO BEGIN THIS AFTERNOON AS LIGHT SNOW AND TRANSITION TO LIGHT FREEZING RAIN. WARMING FROM SOUTH TO NORTH WILL ALSO TAKE PLACE EFFECTIVELY CHANGING FREEZING RAIN TO RAIN IN THE SOUTH. WITH CONCERNS OVER SNOWPACK AND SURFACE TEMPS DID KEEP MENTION OF FREEZING RAIN THROUGH THE NIGHT...USING CHANCE WORDING WITH RAIN SOUTH AND PREDOMINATE FREEZING RAIN WORDING NORTH. ICE ACCUMULATION IS EXPECTED TO BE UP TO A TENTH OF AN INCH WITH HIGHEST AMOUNTS NORTH IN DEEPER COLD AIR REGIME...ASSUMING WARMING BY MODELS IS CORRECT. IF SNOWPACK INHIBITS THE WARMING WE COULD SEE SLIGHTLY HIGHER ICE ACCUMS CLOSER TO TWO TENTHS OF AN INCH. WITH MAIN IMPACT BEING SECOND PERIOD AND STILL QUESTIONS CONCERNING SURFACE TEMPS HAVE OPTED TO NOT ISSUE ANY HEADLINES BUT WILL CONTINUE TO HIGHLIGHT IN HAZARDOUS WEATHER OUTLOOK FOR TONIGHT.
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