IsentropicLift Posted March 27, 2014 Share Posted March 27, 2014 Flash flood guidance for much of NE PA is 2" in 12 hours. http://forecast.weather.gov/product.php?site=NWS&product=FFG&issuedby=PA2 2-3" of rain over a weekend won't cause any major problems here. We have been dry all month. If you want to believe the ECMWF/NAM over an inch of rain falls in about a 6 hour period. It's going to be very close right now. We're right on the verge between nuisance issues and significant issues. Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 27, 2014 Share Posted March 27, 2014 I'm really confused as to why a few posters are calling this a 2-3" rainfall spread over three days. More than half of that is set to fall in 12 hours or less with lighter rain before and afterwards. Link to comment Share on other sites More sharing options...
scooter13 Posted March 27, 2014 Share Posted March 27, 2014 What is the timing of this? Will Friday night or Sat. during the daytime be affected? Link to comment Share on other sites More sharing options...
Stormlover74 Posted March 27, 2014 Share Posted March 27, 2014 I'm really confused as to why a few posters are calling this a 2-3" rainfall spread over three days. More than half of that is set to fall in 12 hours or less with lighter rain before and afterwards. Its about 1.5" in 12 hours and 2" in 18 hours around NYC. I agree some areas can see much higher amounts but too soon to know where that sets up Link to comment Share on other sites More sharing options...
ag3 Posted March 27, 2014 Share Posted March 27, 2014 What does it show for surface temperatures? 34-38 degrees. I agree that it's likely rain as verification. 2"-4" of rain on the way. Link to comment Share on other sites More sharing options...
Stormlover74 Posted March 27, 2014 Share Posted March 27, 2014 What is the timing of this? Will Friday night or Sat. during the daytime be affected? Light amounts until Saturday afternoon.. Heaviest into Sunday morning then light amounts again Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 27, 2014 Share Posted March 27, 2014 34-38 degrees. I agree that it's likely rain as verification. 2"-4" of rain on the way. It could be a few mood flakes or sleet pellets but I certainly wouldn't count on it. Essentially the best dynamics will outrun this low as the jet streak races northeastward. It's not a true cut off low. Just multiple pieces of energy ejecting over the same areas and then lingering precip from an ULL as it passes off the coast and fills. Link to comment Share on other sites More sharing options...
SnowGoose69 Posted March 27, 2014 Share Posted March 27, 2014 I'm really confused as to why a few posters are calling this a 2-3" rainfall spread over three days. More than half of that is set to fall in 12 hours or less with lighter rain before and afterwards. Yeah I have no idea what happens beyond 00z Sunday evening it's probably spotty showers more than anything else, models are clueless with upper lows and cutoffs Link to comment Share on other sites More sharing options...
jm1220 Posted March 27, 2014 Share Posted March 27, 2014 If you want to believe the ECMWF/NAM over an inch of rain falls in about a 6 hour period. It's going to be very close right now. We're right on the verge between nuisance issues and significant issues. There might be minor flooding for a short period of time if the 2" in 12 hour predictions verify. That's the beginning (and actually below) flash flood guidance for the counties that would be impacted. There would need to be a long pattern of significant rain events before serious flooding issues would occur. This looks to be little more than a rainy, dreary, cold weekend with some localized flooding where the rain trains overhead for a while. Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 27, 2014 Share Posted March 27, 2014 Yeah I have no idea what happens beyond 00z Sunday evening it's probably spotty showers more than anything else, models are clueless with upper lows and cutoffs We'll have to watch the strength and speed and location of the 500mb jet as the axis of heaviest rainfall will ride the nose. All the models are in good agreement on an area of very heavy rainfall developing along and just to the north of wherever this sets up. Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 27, 2014 Share Posted March 27, 2014 There might be minor flooding for a short period of time if the 2" in 12 hour predictions verify. That's the beginning (and actually below) flash flood guidance for the counties that would be impacted. There would need to be a long pattern of significant rain events before serious flooding issues would occur. This looks to be little more than a rainy, dreary, cold weekend with some localized flooding where the rain trains overhead for a while. I would agree that right now we should avoid any major issues. It's what happens if we see widespread 3-4" totals. The pattern by no means looks to dry out after this weekend. Link to comment Share on other sites More sharing options...
bluewave Posted March 27, 2014 Share Posted March 27, 2014 There might be minor flooding for a short period of time if the 2" in 12 hour predictions verify. That's the beginning (and actually below) flash flood guidance for the counties that would be impacted. There would need to be a long pattern of significant rain events before serious flooding issues would occur. This looks to be little more than a rainy, dreary, cold weekend with some localized flooding where the rain trains overhead for a while. Maybe we could swing a nice day or two here heading into early April as we lose the source of Arctic air but will have to deal with a string of lows crossing the country. Just need a day or two where the back door fronts get pushed north for a brief time before cooler and raw weather returns. Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 27, 2014 Share Posted March 27, 2014 SREF's increased precip totals by ~0.50" across the board. Link to comment Share on other sites More sharing options...
SnowGoose69 Posted March 27, 2014 Share Posted March 27, 2014 We'll have to watch the strength and speed and location of the 500mb jet as the axis of heaviest rainfall will ride the nose. All the models are in good agreement on an area of very heavy rainfall developing along and just to the north of wherever this sets up. Really starting to get alot of inquiries now about it due to opening day on Monday. I'm just not sure I see that sort of precip in downslope flow from the NW on the west side of a 500 low...typically 500 lows when they are by themselves or cutoff produce most precip NNE of them in the WAA or due north or NNW of the center by 50-100 miles...seeing that sort of precip on the W or WSW side is possible but its less possible here where any sort of WNW or NW flow downslopes and dries us...the 12Z Euro looks to have a secondary surface low max SW of the big low which may be causing the precip more than anything. Link to comment Share on other sites More sharing options...
Stormlover74 Posted March 27, 2014 Share Posted March 27, 2014 Upton going with mostly sunny for Monday. No mention of rain. Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 27, 2014 Share Posted March 27, 2014 The Euro ensemble mean is a soaker. Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 27, 2014 Share Posted March 27, 2014 Link to comment Share on other sites More sharing options...
nyblizz44 Posted March 27, 2014 Share Posted March 27, 2014 Naturally since this is virtually all rain the Euro goes bonkers. Gosh if this snow, the world would stand still! Link to comment Share on other sites More sharing options...
Stormlover74 Posted March 28, 2014 Share Posted March 28, 2014 Nam about 1.5" through Sunday morning.. Mostly dry tomorrow Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 28, 2014 Share Posted March 28, 2014 Nam about 1.5" through Sunday morning.. Mostly dry tomorrowThe 4k NAM is almost double that. Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 28, 2014 Share Posted March 28, 2014 Link to comment Share on other sites More sharing options...
bluewave Posted March 28, 2014 Share Posted March 28, 2014 Looking like the typical heavy overruning event where the heaviest falls north and west of NYC. If NYC can pick up two inches of rain it would only be the third time since last June with the last events in November and June. Link to comment Share on other sites More sharing options...
REDMK6GLI Posted March 28, 2014 Share Posted March 28, 2014 Looking like the typical heavy overruning event where the heaviest falls north and west of NYC. If NYC can pick up two inches of rain it would only be the third time since last June with the last events in November and June. f84.jpg This outcome looks far more likely. The current setup brings the training heavy rains north and west of NYC while I-95 east will get their rains from embedded heavy showers Link to comment Share on other sites More sharing options...
Weathergun Posted March 28, 2014 Share Posted March 28, 2014 Heaviest rainfall totals likely NW of NYC. The best forcing is inland, with the LLJ further west causing more convergence and upsloping. But then this gives more MUCAPE and PWATS for elevated convection near the coast. So we have to watch that as well on Saturday night Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 28, 2014 Share Posted March 28, 2014 .HYDROLOGY...DRY TONIGHT. ANYWHERE FROM A FEW HUNDREDTHS TO UP TO A QUARTER OF ANINCH OF RAIN INTO THIS EVENING. THUS...NO HYDROLOGIC ISSUES ARE EXPECTEDTHROUGH TONIGHT.THERE IS A CHANCE FOR A NEEDED WIDESPREAD 2 TO 4 INCH RAINFALLSATURDAY INTO MONDAY MORNING...WITH LOCALLY HIGHER AMOUNTSPOSSIBLE. A COMBINATION OF DRY ANTECEDENT CONDITIONS AND THE LONGDURATION OF THE EVENT MAKE MINOR URBAN FLOODING THE MOST LIKELYTHREAT. HOWEVER...WITH THE POSSIBILITY OF SOME ELEVATEDCONVECTION...THE THREAT OF MORE SIGNIFICANT AND/OR EXTENSIVEFLOODING CANNOT BE RULED OUT. .HYDROLOGY...FOR SATURDAY AND SUNDAY, THE PW VALUES ARE FORECAST TO INCREASE TOABOUT 1.0-1.5 INCHES DURING THEIR PEAK. THE HIGHEST VALUES AREMAINLY ACROSS THE EASTERN AND SOUTHERN ZONES. THE AVAILABLE MOISTUREIN COMBINATION OF A SLOW MOVING SYSTEM AND WIDESPREAD LARGE SCALELIFT WILL LEAD TO PERIODS OF RAIN, SOME OF WHICH WILL BE HEAVY ATTIMES. IN GENERAL, GUIDANCE IS INDICATING 1-3 INCHES OF RAIN ACROSSTHE AREA. THERE WILL PROBABLY BE AREAS THAT HAVE SOME ENHANCEDRAINFALL, AND THIS WILL GENERALLY BE WHERE THE MID LEVEL CONVERGENCESETS UP. THIS VARIES SOME AMONG THE GUIDANCE, HOWEVER THE INTERSTATE95 CORRIDOR TO THE NORTH AND WEST SEEM TO HAVE A HIGHER CHC ATTM.THE HEAVY RAIN SHOULD RESULT IN SOME FLOODING IN AREAS OF POORDRAINAGE, HOWEVER EVEN SMALLER STREAMS AND CREEKS WILL NEED TO BEWATCHED ESPECIALLY IF THE HIGHER AMOUNTS ARE MORE WIDESPREAD.LUCKILY MUCH OF THE AREA HAS NO SNOW COVER, SO ADDED RUNOFF FROMTHIS WILL NOT BE A FACTOR. THE SCOPE OF ANY FLOODING OUTSIDE OF POORDRAINAGE AREAS IS STILL A BIT UNCERTAIN, THEREFORE A FLOOD WATCHWILL NOT BE ISSUED ATTM. A MENTION OF HEAVY RAIN DOES REMAIN IN THEHAZARDOUS WEATHER OUTLOOK.&& Link to comment Share on other sites More sharing options...
jm1220 Posted March 28, 2014 Share Posted March 28, 2014 This will probably be the usual 1-2" of rain along the coast and 2-4" of rain inland, with much of the rain along the coast being the showery kind and the steady heavy rain inland. The best forcing and LLJ dynamics are leaning heavily that way. Link to comment Share on other sites More sharing options...
hudsonvalley21 Posted March 28, 2014 Share Posted March 28, 2014 06z NAM came in colder with about 0.75 of ZR for KSWF. Not too low below 32 so it should not be too bad if it verified. 140331/0300Z 69 01019KT 31.9F FZRA 0:1| 0.0|| 0.00|| 0.01|| 0.006 0:1| 0.0|| 0.00|| 0.01|| 0.11 0| 0|100140331/0400Z 70 36018KT 31.5F FZRA 0:1| 0.0|| 0.00|| 0.03|| 0.026 0:1| 0.0|| 0.00|| 0.03|| 0.13 0| 0|100140331/0500Z 71 36018KT 31.4F FZRA 0:1| 0.0|| 0.00|| 0.04|| 0.039 0:1| 0.0|| 0.00|| 0.07|| 0.17 0| 0|100140331/0600Z 72 36018KT 31.4F FZRA 0:1| 0.0|| 0.00|| 0.03|| 0.031 0:1| 0.0|| 0.00|| 0.11|| 0.20 0| 0|100----------------------------------------------+----++-----+-------------++--------------++-------------++-----------+---+---140331/0700Z 73 36017KT 30.3F FZRA 0:1| 0.0|| 0.00|| 0.07|| 0.069 0:1| 0.0|| 0.00|| 0.18|| 0.27 0| 0|100140331/0800Z 74 36017KT 30.1F FZRA 0:1| 0.0|| 0.00|| 0.05|| 0.052 0:1| 0.0|| 0.00|| 0.23|| 0.32 0| 0|100140331/0900Z 75 36016KT 30.6F FZRA 0:1| 0.0|| 0.00|| 0.03|| 0.031 0:1| 0.0|| 0.00|| 0.26|| 0.35 0| 0|100140331/1000Z 76 36016KT 30.6F FZRA 0:1| 0.0|| 0.00|| 0.03|| 0.027 0:1| 0.0|| 0.00|| 0.29|| 0.38 0| 0|100140331/1100Z 77 36015KT 30.1F FZRA 0:1| 0.0|| 0.00|| 0.08|| 0.072 0:1| 0.0|| 0.00|| 0.37|| 0.45 0| 0|100140331/1200Z 78 36015KT 30.8F FZRA 0:1| 0.0|| 0.00|| 0.16|| 0.152 0:1| 0.0|| 0.00|| 0.53|| 0.60 0| 0|100----------------------------------------------+----++-----+-------------++--------------++-------------++-----------+---+---140331/1300Z 79 36015KT 31.0F FZRA 0:1| 0.0|| 0.00|| 0.16|| 0.154 0:1| 0.0|| 0.00|| 0.69|| 0.76 0| 0|100140331/1400Z 80 36014KT 31.7F FZRA 0:1| 0.0|| 0.00|| 0.11|| 0.100 0:1| 0.0|| 0.00|| 0.79|| 0.86 0| 0|100140331/1500Z 81 36014KT 32.8F RAIN 0:1| 0.0|| 0.00|| 0.00|| 0.060 0:1| 0.0|| 0.00|| 0.79|| 0.92 0| 0|100140331/1600Z 82 01013KT 33.7F RAIN 0:1| 0.0|| 0.00|| 0.00|| 0.062 0:1| 0.0|| 0.00|| 0.79|| 0.98 0| 0|100140331/1700Z 83 36013KT 34.2F RAIN 0:1| 0.0|| 0.00|| 0.00|| 0.058 0:1| 0.0|| 0.00|| 0.79|| 1.04 0| 0|100140331/1800Z 84 36013KT 35.5F DZ 0:1| 0.0|| 0.00|| 0.00|| 0.021 0:1| 0.0|| 0.00|| 0.79|| 1.06 0| 0|100 Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 28, 2014 Share Posted March 28, 2014 This will probably be the usual 1-2" of rain along the coast and 2-4" of rain inland, with much of the rain along the coast being the showery kind and the steady heavy rain inland. The best forcing and LLJ dynamics are leaning heavily that way. Agreed, my area looks to be ground zero, although I believe that the city will still see >2" while the I-287 corridor sees 2-4" widespread. The 06z NAM still has the area near the right exit region of the 250mb jet. Link to comment Share on other sites More sharing options...
IsentropicLift Posted March 28, 2014 Share Posted March 28, 2014 It's going to be over looked some because it's a rainstorm but the models once again did an excellent job of picking out this storm in the medium/long range. Look at how juiced the 00z ECMWF ensembles were last night. I think a 2-3" forecast is conservative today. Link to comment Share on other sites More sharing options...
REDMK6GLI Posted March 28, 2014 Share Posted March 28, 2014 It's going to be over looked some because it's a rainstorm but the models once again did an excellent job of picking out this storm in the medium/long range. Look at how juiced the 00z ECMWF ensembles were last night. I think a 2-3" forecast is conservative today. KEWR_2014032800_eps_precip_240.png Yes they did an excellent job. We both agreed N&W of NYC would be ground zero for training heavy rain, however stated earlier the chance for elevated convection with sufficient amount of CAPE along the coast is possible late saturday. Winds may also be gusting north of 35mph as well with this system along coastal locals Link to comment Share on other sites More sharing options...
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